JPH08232711A - Start fuel injection timing control device for internal combustion engine - Google Patents

Abstract

PURPOSE: To prevent fuel blow by at starting and reduce starting time by calculating injection timing based on overlapping start time of an intake/exhaust valve, reached time of injected fuel to a combustion chamber and fuel injection time. CONSTITUTION: ECU 5 operates injection time of fuel by a fuel injection valve 6 and detects at least one of engine rotational frequency by a CRK sensor 13, engine temperature by a water temperature sensor 10 and intake air temperature of an engine by an intake temperature sensor 9 and reaching time of the injected fuel to a combustion chamber using various table data in response to this detected output. The ECU 5 further operates overlap timing when an intake valve and an exhaust valve of the engine 1 are simultaneously opened. Fuel injection timing is calculated based on the overlap start time, the fuel reaching time and the fuel injection time preferably such that the fuel injection is finished before the overlap start time. Whereby, blow by of the fuel is prevented to reduce emission.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, it has been known that the timing of fuel injection influences emissions, motion performance, etc., and the fuel injection of an internal combustion engine is controlled in accordance with the operating conditions of the internal combustion engine. A control device is known (see, for example, Japanese Patent Publication No. 5-24344).

[0003]

However, in the above conventional fuel injection control device for an internal combustion engine, since the injection timing at the time of engine start is not taken into consideration, at the time of engine start at a low engine speed, the intake valve and The time when both exhaust valves are open, that is, the overlap time becomes longer, the amount of fuel that is sucked into the combustion chamber and blows through the exhaust valve as it is may increase, and as a result, the startup time increases. Emissions may increase as you do.

The present invention has been made in view of the above-mentioned points, and an internal combustion engine capable of preventing blow-through of fuel at the time of starting the engine, thereby shortening the starting time and reducing emissions. An object is to provide a starting fuel injection timing control device.

[0005]

In order to achieve the above object, the present invention is directed to a start of an internal combustion engine in which a fuel injection means for injecting fuel into an intake pipe of the internal combustion engine determines a timing of injecting fuel at the time of starting the engine. In a fuel injection timing control device, a fuel injection time calculation means for calculating a fuel injection time, and an operation state detection means for detecting at least one of the engine speed, the engine temperature and the intake air temperature of the engine. And the arrival time calculation means for calculating the arrival time required for the injected fuel to reach the combustion chamber according to the output of the operating state detection means, and the intake valve and the exhaust valve of the internal combustion engine are simultaneously opened. Overlap start timing calculation means for calculating the overlap start timing, and fuel consumption based on the overlap start timing, the arrival time, and the fuel injection time. And having a fuel injection timing calculating means for calculating the injection timing.

Further, preferably, the fuel injection timing calculation means calculates the fuel injection timing so as to finish the fuel injection before the overlap start timing.

Further, preferably, the fuel injection timing calculation means calculates a time point which is before the predicted overlap start time by a time obtained by adding the arrival time and the fuel injection time as a fuel injection start timing. It is characterized by

[0008]

According to the structure of the present invention, the fuel injection time is calculated, at least one of the engine speed, the engine temperature and the engine intake air temperature is detected, and the fuel is injected according to the detected output. The arrival time at which the fuel reaches the combustion chamber is calculated, the overlap start timing at which the intake valve and the exhaust valve of the internal combustion engine are simultaneously opened is calculated, and the overlap start period, the arrival time and the fuel injection time are calculated. Based on this, the fuel injection timing is calculated.

Further, preferably, the fuel injection timing is calculated so that the fuel injection is ended before the overlap start timing.

Further, preferably, a time point before the predicted overlap start time by a time obtained by adding the arrival time and the fuel injection time is calculated as the fuel injection start timing.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is an overall configuration diagram of an internal combustion engine (hereinafter referred to as "engine") and a control system therefor according to one embodiment of the present invention.

In the figure, reference numeral 1 is a four-cylinder engine, and the engine 1 is provided with an intake valve and an exhaust valve (not shown) for each cylinder.

A throttle body 3 is provided in the middle of an intake pipe 2 of the engine 1, and a throttle valve 3'is provided therein.
Is arranged. A throttle valve opening (θTH) sensor 4 is connected to the throttle valve 3 ′, and outputs an electric signal according to the opening of the throttle valve 3 ′ to output an electronic control unit (hereinafter referred to as “ECU”) 5. To supply.

The fuel injection valve 6 is connected between the engine 1 and the throttle valve 3'and to a fuel pump (not shown) of the intake pipe 2 and is electrically connected to the ECU 5, and the EC
The valve opening time of fuel injection is controlled by the signal from U5.

A branch pipe 7 is provided downstream of the throttle valve 3'of the intake pipe 2, and an absolute pressure (PBA) sensor 8 is attached to the tip of the branch pipe 7. The PBA sensor 8 is electrically connected to the ECU 5, and the intake pipe 2
The absolute pressure PBA therein is converted into an electric signal by the PBA sensor 8 and supplied to the ECU 5.

An intake air temperature (TA) sensor 9 is mounted on the wall of the intake pipe 2 downstream of the branch pipe 7, and the intake air temperature TA detected by the TA sensor 9 is converted into an electric signal.
It is supplied to the ECU 5.

An engine water temperature (TW) sensor 10 including a thermistor or the like is attached to the cylinder peripheral wall filled with cooling water of the cylinder block of the engine 1, and the engine cooling water temperature TW detected by the TW sensor 10 is converted into an electric signal. It is converted and supplied to the ECU 5.

Cylinder discrimination (CYL) is performed at a predetermined position around the cam shaft or crank shaft (not shown) of the engine 1.
Sensor 11, TDC sensor 12, crank angle (CRK)
Each of the sensors 13 is attached.

The CYL sensor 11 outputs a pulse signal (hereinafter referred to as "CYL signal pulse") at a predetermined crank angle position of a specific cylinder for every two rotations of the crankshaft, and the C signal is output.
The YL signal pulse is supplied to the ECU 5.

The TDC sensor 12 outputs a signal pulse (hereinafter referred to as "TDC signal pulse") at a predetermined crank angle position every 180 ° rotation of the crankshaft of the engine 1, and supplies the TDC signal pulse to the ECU 5. .

The CRK sensor 13 outputs a pulse signal (hereinafter referred to as "CRK") at a cycle of the TDC signal pulse, that is, a constant crank angle cycle shorter than 180 ° (for example, 30 ° cycle).
Signal pulse ”) and supplies the CRK signal pulse to the ECU 5.

The output signal pulses of the CYL sensor 11, the TDC sensor 12, and the CRK sensor 13 indicate the fuel injection timing,
Various timing control such as ignition timing and engine speed N
Used to detect E.

The ECU 5 shapes the input signal waveforms from the above-mentioned various sensors, corrects the voltage level to a predetermined level, converts the analog signal value into a digital signal value, and the like, and the following description. A central processing circuit (hereinafter referred to as "CPU") 5b for executing various processes, a storage unit 5c including a ROM and a RAM for storing various calculation programs executed by the CPU, various maps to be described later, calculation results, and the like, An output circuit 5d for supplying a drive signal to the fuel injection valve 6 is provided.

FIG. 2 is a diagram showing the relationship between the combustion stroke in a cylinder of the engine 1 and the lift amounts of the intake valve and the exhaust valve, and the figure also shows the stage (STG). Here, the stage is a number in which the time interval between the CRK signal pulses is sequentially numbered until the start of the compression stroke is numbered 0 and the suction stroke is completed. That is, in this embodiment, one pulse of the CRK signal pulse is output every 30 ° of rotation of the crankshaft, and the crankshaft outputs 7 pulses during the combustion process.
Each stage is numbered 0 to 23 because the entire process is completed when rotated by 20 °.

The control process executed by the engine control device configured as described above will be described below with reference to the flowchart of FIG.

FIG. 3 is a flow chart showing the procedure of the injection stage determination process executed by the CPU 5b. In this embodiment, the injection stage (INJ.STG) means a stage in which the fuel injection valve 6 is opened to start fuel injection.

In the figure, first, it is determined whether or not the engine is in the starting mode (whether or not the cranking is being performed) (step S1). When not in the starting mode, the engine speed N
After determining the injection stage by searching the map NE-PBA map for determining the injection stage according to E and the intake pipe absolute pressure PBA (step S2), this injection stage determination process is ended.

On the other hand, when it is determined in step S1 that the engine is in the starting mode, it is determined whether or not sequential injection for sequentially injecting fuel is performed for each cylinder (step S3). Here, whether or not to perform the sequential injection is determined by whether or not the first CYL signal pulse is detected after the start of the engine. Specifically, the CYL signal pulse is constantly monitored after the start of the engine, and a flag is set, for example, at the time when the first CYL signal pulse is detected. In step S3, the state of this flag may be determined. .

When it is determined in step S3 that the sequential injection is not performed, that is, when the first CYL signal pulse is not detected, the simultaneous injection for simultaneously injecting fuel to all cylinders is performed after the detection of the first TDC signal pulse. Then, the injection stage determination process is completed (step S4).

On the other hand, when the sequential injection is performed in the determination of step S3, the delay time TDEL until the fuel injection valve 6 is opened and the injected fuel reaches the cylinder.
AY is determined by searching table data having the engine speed NE as a parameter (step S
5), the determined delay time TDELAY is corrected by the following equation using the correction coefficients KTDLYTW and KTDLYTA,
The corrected delay time TDELAY is calculated (step S
5).

TDELAY = TDELAY × KTDLY
TW × KTDLYTA where the correction coefficients KTDLYTW and KTDLYTA are
It is determined by searching each table data with the engine water temperature TW and the intake air temperature TA as parameters.

FIG. 4 shows table data and correction coefficients KTDLYTW, K for determining the delay time TDELAY.
It is a graph of table data for determining TDLYTA. In the figure, (a) is a graph of table data for determining the delay time TDELAY, and the horizontal axis indicates the engine speed NE,
The vertical axis represents the delay time TDELAY. (B) is
The table data for determining the correction coefficient KTDLYTW is graphed, and the horizontal axis represents the engine water temperature TW.
The vertical axis represents the correction coefficient value KTDLYTW. (C) is a graph of table data for determining the correction coefficient KTDLYTA, in which the horizontal axis represents the intake air temperature TA and the vertical axis represents the correction coefficient value KTDLYTA. That is, the delay time TDELAY is determined from (a) according to the engine speed NE, and the correction coefficient KTD is determined from (b) according to the engine water temperature TW at this time.
LYTW is determined, and the intake air temperature TA at this point
Accordingly, the correction coefficient KTDLYTA is determined from (c), and the corrected delay time TDELAY is calculated by the above equation.

Returning to FIG. 3, in step S7, the number of stages NDELAY corresponding to the corrected delay time TDELAY is calculated by the following equation.

NDELAY = TDELAY / CRME Here, CRME is the time interval of each stage, that is, the time interval between CRK signal pulses.

In the following step S8, the fuel injection end target STG (stage) is calculated by the following equation.

Fuel injection end target STG = 16 (ST
G) -NDELAY Here, the stage "16" is a stage in which the overlap period starts as shown in FIG. 2, and the fuel injected by the end of this stage reaches the inside of the cylinder. The fuel injection end target STG is determined.

In the following step S9, as in step S7, the time during which the fuel injection valve 6 is opened, that is, the fuel injection time Ti is divided by the value CRME to determine the number of stages corresponding to the fuel injection time Ti. Is calculated and the injection start STG (stage) is determined by the following equation, and then this processing is ended.

Injection start STG = fuel injection end target ST
G-Ti / CRME Therefore, the delay time TDE after the injection start STG is corrected
The following equation can be expressed by LAY and fuel injection time Ti.

Injection start STG = 16- (TDELA
(Y + Ti) / CRME As described above, in the present embodiment, the fuel injection timing is set so that most of the injected fuel does not reach the cylinder during the overlap, depending on the operating state of the engine at the time of starting. Is controlled, it is possible to prevent blow-through of fuel, thereby shortening the starting time and reducing emissions.

[0041]

As described above, according to the present invention,
The fuel injection time is calculated, at least one of the engine speed, the engine temperature, and the intake air temperature of the engine is detected, and the arrival time for the injected fuel to reach the combustion chamber is calculated according to the detected output. Then, the overlap start timing at which the intake valve and the exhaust valve of the internal combustion engine are simultaneously opened is calculated,
Since the fuel injection timing is calculated based on the overlap start period, the arrival time, and the fuel injection time, it is possible to prevent the fuel from passing through at the time of engine start, thereby shortening the start time and reducing the emission. The effect that can be achieved is achieved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an engine and its control device according to an embodiment of the present invention.

2 is a diagram showing a relationship between a combustion stroke and a lift amount of an intake valve and an exhaust valve in a cylinder of the engine of FIG.

FIG. 3 is a flowchart showing a procedure of injection stage determination processing executed by the CPU of FIG.

FIG. 4 is table data for determining a delay time TDELAY and correction coefficients KTDLYTW, KTDLYTA.
It is the figure which made the graph the table data in order to decide.

[Explanation of symbols]

5 ECU (fuel injection time calculation means, arrival time calculation means, overlap start timing prediction means, fuel injection timing calculation means) 13 CRK sensor

Claims (3)

[Claims] 1. A starting fuel injection timing control device for an internal combustion engine, wherein a fuel injection means for injecting fuel into an intake pipe of an internal combustion engine determines a timing of injecting fuel at the time of starting the engine, and calculates a fuel injection time. Fuel injection time calculating means, operating state detecting means for detecting at least one of the engine speed, the engine temperature, and the intake air temperature of the engine, and injection is performed according to the output of the operating state detecting means. Arrival time calculation means for calculating an arrival time required for the fuel to reach the combustion chamber, and overlap start timing calculation means for calculating an overlap start timing at which the intake valve and the exhaust valve of the internal combustion engine are simultaneously opened. , Fuel injection timing for calculating fuel injection timing based on the overlap start timing, the arrival time and the fuel injection time Starting fuel injection timing control apparatus for an internal combustion engine and having an output means. 2. The starting fuel injection for an internal combustion engine according to claim 1, wherein the fuel injection timing calculation means calculates the fuel injection timing so as to finish the fuel injection before the overlap start timing. Timing control device. 3. The fuel injection timing calculation means calculates, as the fuel injection start timing, a time point which is before the predicted overlap start time by a time obtained by adding the arrival time and the fuel injection time. The starting fuel injection timing control device for an internal combustion engine according to claim 1 or 2.