JPH109031A - Fuel injection timing control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection timing control device which can inject the fuel at an optimum timing according to the operating condition of an engine. SOLUTION: When it is at the starting time, the process is advanced to Step 4, and the fuel injection finishing timing at the starting is read from a map where the fuel injection finishing timing corresponding to the engine rotational frequency at the starting is given (Step 4). When it is decided to be in an acceleration operation, the fuel injection finishing timing in the acceleration condition is read from a map indicating the fuel injection finishing timing in the acceleration operation (Step 6). When it is decided to be a normal operation condition, the fuel injection finishing timing in the normal operation condition is read from a map indicating the fuel injection finishing timing in a normal operation condition (Step 7). The fuel injection time TAU is calculated (Step 8), and the fuel injection starting timing is calculated by reducing the fuel injection time from the fuel injection finishing timing (Step 9).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection timing control device for an internal combustion engine, and more particularly to a fuel injection timing control device for an independent injection type internal combustion engine that injects fuel at an independent injection timing for each cylinder.

[0002]

2. Description of the Related Art In an independent injection type internal combustion engine in which fuel is injected at an independent injection timing for each cylinder, fuel can be injected at an optimum fuel injection timing for each cylinder. Therefore, there is disclosed an apparatus in which the fuel injection timing is set at a predetermined time after a predetermined crank angle position when the engine is started (Japanese Patent Application Laid-Open No. 60-1985).
233351).

If the injection of fuel is terminated before the intake valve opens, the injected fuel stays in front of the intake valve. However, if the engine is not warmed up, it disadvantageously adheres to the intake port wall and the back surface of the intake valve. Conversely, if the fuel injection is terminated after the intake valve opens, the injected fuel does not stay in front of the intake valve and is less likely to adhere to the intake port wall or the back surface of the intake valve, and the response is good. However, on the other hand, even if the engine is warmed up, the heat cannot be used to promote atomization. Therefore, when the engine is not warmed up or during acceleration, the fuel injection timing is delayed so that the intake valve is opened and then terminated, and when the engine is warmed up, the fuel injection timing is advanced and the intake valve is opened. It is desirable that the fuel injection be terminated before opening, that is, the fuel injection timing be changed in accordance with the temperature of the engine.

[0004]

However, the fuel injection timing at the time of starting in the apparatus disclosed in the above publication is constant regardless of the temperature of the engine. Therefore, when the engine is started in a cold state with a low engine temperature, the amount of fuel adhering to the intake port wall and the back of the intake valve increases, and various increase corrections are performed to correct the increase. I have. As a result, there is a problem that deterioration of exhaust emission and fuel efficiency are caused.

The present invention has been made in view of the above problems, and has as its object to provide a fuel injection timing control device capable of injecting fuel at an optimum injection timing according to an operating state of an engine.

[0006]

According to the first aspect of the present invention, there is provided a fuel injection timing control apparatus for an independent injection type internal combustion engine which injects fuel at an independent injection timing for each cylinder. Operating state detecting means for detecting the operating state, and fuel injection timing setting means for setting the fuel injection timing according to the operating state detected by the operating state detecting means, wherein the fuel injection timing setting means includes at least an intake valve of the engine. The maximum delay side injection timing set to close the fuel injection valve after the valve is opened, and the maximum advance side set to close the fuel injection valve at least before the intake valve of the engine opens. A fuel injection timing control device characterized in that the injection timing can be continuously changed between the injection timing and the injection timing.

[0007] In the fuel injection timing control device configured as described above, the injection timing of the fuel injection valve is set to the maximum lag side injection timing set so that the fuel injection valve is closed after the intake valve of the engine is opened. Optimally set according to the operating state between the maximum early injection timing set so that the fuel injection valve is closed before the intake valve of the engine opens.

According to a second aspect of the present invention, in the first aspect of the present invention, the operating state detecting means includes a warming-up degree detecting means for detecting a warming-up degree of the engine, and the fuel injection timing setting means comprises: Between the maximum delay injection timing and the maximum advance injection timing, the lower the warm-up degree detected by the warm-up degree detecting means, the slower the fuel injection valve closes, and the higher the warm-up degree, the earlier the fuel injection valve. A fuel injection timing control device configured to close a valve is provided.

In the fuel injection timing control device configured as described above, between the maximum delay side injection timing and the maximum early side injection timing, the lower the degree of warm-up, the later the fuel injection valve is closed, and the degree of warm-up is reduced. The fuel injection timing is set such that the fuel injection valve is closed earlier as the fuel injection valve is higher.

According to a third aspect of the present invention, in the first aspect of the invention, the operating state detecting means includes a cranking speed detecting means for detecting a cranking speed at the time of starting the engine, and the fuel injection timing setting is performed. The means, between the maximum delay side injection timing and the maximum advance side injection timing, closes the fuel injection valve more slowly as the cranking rotation speed detected by the cranking rotation speed detection means is lower, and the cranking rotation speed becomes lower. The fuel injection timing at the start is set so that the higher the fuel injection valve is, the faster the fuel injection valve is closed.
There is provided a fuel injection timing control device in which a fuel injection timing is shifted from the fuel injection timing at the time of starting to the maximum earlier injection timing.

In the fuel injection timing control device thus configured, the fuel injection timing at the start is set according to the cranking speed, and the fuel injection timing is set according to the increase of the cranking speed. The injection timing is shifted from the injection timing to the maximum earlier injection timing.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing a configuration of an embodiment of the present invention, wherein 1 is an engine main body, and the engine main body 1 is a four-cylinder engine having four cylinders.
A fuel injection valve 3 is attached to each intake manifold 2 connected to an intake port (not shown) of each cylinder, which is a so-called independent injection type engine. Surge tank 4 upstream of intake manifold 2
The intake pipe 5 is attached to the intake pipe 5, and an air flow meter 6 and an intake pipe negative pressure sensor 7 are attached to the intake pipe 5. Further, a crank angle sensor 8 for detecting a crank angle and a coolant temperature sensor 9 for detecting a temperature of engine coolant are attached to the engine body. The crank angle sensor 8 calculates the engine speed according to the present invention,
In addition to being used for setting the injection timing, it is used for calculating and setting the ignition timing. 10 is an exhaust manifold, 11 is an exhaust pipe, and 12 is a catalytic converter. An air-fuel ratio sensor 13 is attached to the exhaust pipe 11 upstream of the catalytic converter 12.

Reference numeral 20 denotes an engine control unit (hereinafter referred to as an ECU). The ECU 20 is composed of a digital computer, and has an input interface circuit 21 and an ADC (analog-to-digital converter) 2 connected to each other.
2. CPU (microprocessor) 23, RAM (random access memory) 24, backup RAM 24
a, a ROM (Read Only Memory) 25, an output interface circuit 26, and the like.

The CPU 23 outputs an output signal of each sensor to
It is input via the input interface circuit 21 or further via the ADC 22. The CPU 23 performs a later-described calculation from the values of these various sensors and the values stored in the ROM 25 in advance, and performs various other control calculations for controlling the fuel injection timing.

Next, the fuel injection timing control in the embodiment of the present invention configured as described above will be described. In this embodiment, the operating state is first classified according to whether the engine is started (when the starter switch is turned on and cranked by the starter) or not. In the case other than the start, the operation is further divided into a steady operation and an acceleration operation.
On the other hand, the fuel injection end timing for each of the starting, the steady operation, and the acceleration operation is stored in a map, and the fuel injection end timing suitable for each operation condition is selected from the map.

In the embodiment of the present invention, the control is performed as described above so that the injection end time becomes a predetermined time.
In order to inject a required amount of fuel and set the end time of the injection to a predetermined timing, the fuel injection start timing is determined as follows. That is, the fuel injection time T defining the fuel injection amount
The AU (= opening time of the fuel injection valve) is calculated based on the map according to the operating conditions, and the fuel injection timing is subtracted from the fuel injection end timing calculated as described above to determine the injection start timing.

Hereinafter, a flowchart of a control routine based on the above concept will be described. In step 1 of the flowchart shown in FIG. 2, it is determined whether the ignition switch is ON. If the ignition switch is ON, the routine is executed. If the ignition switch is OFF, the routine is terminated without executing the routine. If the routine is to be executed with the ignition switch ON, parameters such as cooling water temperature, engine speed, and intake pipe negative pressure are read in step 2 and step 3
Then, it is determined whether it is the time of starting. If it is at the start, the process proceeds to step 4 to calculate the fuel injection end timing at the start from the map.

As shown in FIG. 3, in the map used in step 4, for example, fuel injection end timings corresponding to the engine speed NE are given to three temperature ranges of extremely low temperature, low temperature, and normal temperature. ing. Therefore, for example, when the engine is started at an extremely low temperature and the rotation speed N1, the crank angle indicated by the ordinate value A1 of S1 on the broken line is selected as the end time of the fuel injection. When the rotational speed increases to N2, the crank angle indicated by the ordinate value A2 of S2 on the broken line is selected as the fuel injection end timing. Since this map is applied to an engine that is cranked by a starter motor at the time of engine start, the number of rotations is at most 40.
It is set only up to about 0 rpm.

On the other hand, if it is determined in step 3 that it is not the time of starting, the process proceeds to step 5, and it is determined whether the vehicle is in an acceleration operation or a steady operation. This determination is made based on the magnitude of the suction pipe negative pressure PM. If it is determined that the vehicle is accelerating, the process proceeds to step 6, and the fuel injection end timing at the time of acceleration is calculated from the map. In the present embodiment, for example, as shown in FIG. 4, the map used in step 6 is the fuel injection termination corresponding to the engine speed NE in three temperature ranges of extremely low temperature, low temperature, and normal temperature. Time has been given.
However, when the influence of the water temperature or the rotation speed is small, a single value may be used.

If it is determined in step 5 that the vehicle is operating in a steady state, the process proceeds to step 7 and the fuel injection end timing in the steady state is calculated from the map. In the present embodiment, for example, as shown in FIG. 5, the map used in step 7 is the fuel corresponding to the engine speed NE and the load for three temperature ranges of extremely low temperature, low temperature, and normal temperature. The injection end timing is given.

In step 8, the fuel injection time TAU is calculated. In step 9, the fuel injection time TAU calculated in step 8 is subtracted from the fuel injection end timing read in steps 4, 6, and 7 to set the fuel injection start timing. Calculate and end. Since the fuel injection valve 3 injects fuel only during the fuel injection time TAU from the fuel injection start time obtained as described above, the fuel injection ends at the time read according to the operating conditions.

Hereinafter, the calculation of the fuel injection time in step 8 will be described. First, when starting the engine,
The fuel injection time TAU is calculated by the following equation (1). TAU = TAUST × KNEST × KBST × KPA (1) Here, TUST is a starting basic injection time determined according to the water temperature THW, and is stored in a map shown by a solid line in FIG. KNEST is a correction coefficient based on the engine speed NE, KBST is a correction coefficient based on the battery voltage VB, and KPA is a correction coefficient based on the atmospheric pressure PA.

The broken line in FIG. 6 shows the value of TAUST in the prior art. Since the end timing of fuel injection is not optimized as in the present invention, the amount of adhesion to the wall surface of the intake manifold 2 is large. However, it is set to a large value to make up for it. Conversely, in the present invention, by optimizing the fuel injection end timing, the injection amount at the time of starting can be made smaller than that in the related art.

Next, the calculation of the fuel injection amount after the engine is started will be described. The engine starts and the engine speed N
When E exceeds a predetermined value, the engine intake air amount Q and the engine speed N are set instead of the above equation (1).
It is calculated from the following equation (2) based on E. TAU = GA × KINJ × (1 + FWLOTP) × FAF + FMW (2)

Here, GA is an intake air amount per rotation of the engine (Q / NE), KINJ is a conversion constant for converting the engine intake air amount GA into a basic fuel injection amount, and FW
LOTP is an increase correction coefficient for securing drivability during warm-up and preventing an increase in exhaust gas temperature under high load.
Is an air-fuel ratio correction coefficient generated based on the signal of the air-fuel ratio sensor 9, and FMW is a correction coefficient for correcting the fuel injection amount in consideration of the fuel deposited on the wall surface.

FWLOTP is further represented by the following equation (3). FWLOTP = (FWLB + FWLD) × KWL + FASE (3) Here, FWLB is stored in the map as a basic value for the calculation of FWLOTP, FWLD is a warming-up increasing attenuation coefficient, and KWL is a correction coefficient based on the engine speed. , FASE is a post-start increase coefficient for stabilizing the engine rotation immediately after the start of the engine.

FIG. 7 shows the FW determined according to the water temperature THW.
A map showing the values of LB. The solid line shows the value according to the present invention, and the broken line shows the value according to the prior art. As shown in the figure, in the prior art, the fuel injection end timing is not optimized as in the present invention, so that the amount of adhesion to the wall surface of the intake manifold 2 is large. . Conversely, in the present invention, by optimizing the fuel injection end timing, it is possible to reduce the amount of increase during warm-up and high load compared to the related art.

The FASE is given an initial value FASE ₁ when the calculation of equation (2) is started, and is then attenuated at a predetermined number of revolutions at a predetermined attenuation rate until it becomes zero. Initial value FASE ₁ is read from the map shown solid lines in FIG. 8. Note that the broken line in FIG. 8 indicates the value of FASE _{1 in} the prior art. Since the fuel injection end timing is not optimized as in the present invention, the amount of adhesion to the wall of the intake manifold 2 is large. It is a large value to make up for it. Conversely, in the present invention, the amount of fuel increase after starting can be reduced as compared with the prior art by optimizing the fuel injection end timing.

Since the FAF is not affected by the present invention, it is omitted, and the wall adhesion correction coefficient FMW will be described.
The wall adhesion correction coefficient FMW is for preventing the air-fuel ratio from shifting during a transition. In a steady state (rotational speed, intake pipe pressure, water temperature, etc.), a certain amount of fuel is stably deposited near the intake port of the engine. The amount of fuel stably deposited varies depending on the intake pipe pressure. The higher the absolute pressure of the intake pipe, that is, the higher the load, the larger the amount of adhesion. Conversely, the lower the absolute pressure of the intake pipe, that is, the lower the load, the smaller the amount of adhesion.

Therefore, during acceleration when the intake pipe pressure increases, the amount of fuel adhering increases, and all the injected fuel does not flow into the combustion chamber, the air-fuel ratio becomes lean, and conversely, the intake pipe pressure decreases. At the time of deceleration that becomes lower, the amount of fuel flowing into the combustion chamber increases from the amount of fuel attached to the wall surface, and the air-fuel ratio becomes rich. Therefore, in order to prevent the above-described transition of the air-fuel ratio during the transition, the FMW is increased during acceleration and decreased during deceleration.

Therefore, the fuel amount adhering in the steady state is stored as a map with respect to the intake pipe pressure PM (not shown), and based on the intake pipe pressure PM when the intake valve is closed,
The attached fuel amount QMW is calculated from the map. Then, the change amount DLQMW is obtained, and it is considered that the adhesion amount is insufficient or excessive by this amount, and the amount is increased or decreased by the insufficient amount or excess amount. Since the FMW is roughly calculated as described above, when the fuel injection timing is optimized as in the present invention to reduce the amount of wall adhesion, the FMW correction amount can be reduced.

As described above, according to the present invention, various correction amounts of the fuel injection time (fuel injection amount) can be reduced.
As a result, fuel efficiency is improved and exhaust emissions are improved.

[0033]

According to the present invention, the fuel injected from the fuel injection valve is prevented from adhering to the intake pipe wall surface, the intake port wall surface, the back surface of the intake valve, or the like. The fuel is injected at the optimized fuel injection timing, whereby various correction amounts of the fuel injection time (fuel injection amount) can be reduced, and as a result, fuel efficiency can be improved and exhaust emission can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a flowchart of a routine for calculating a fuel injection timing.

FIG. 3 is a map showing a fuel injection end timing at the time of starting.

FIG. 4 is a map showing a fuel injection end timing during an acceleration operation.

FIG. 5 is a map showing a fuel injection end timing during a steady operation.

FIG. 6 is a diagram showing the value of TAUST in comparison with the prior art.

FIG. 7 is a diagram showing a value of FWLB in comparison with a conventional technique.

FIG. 8 is a diagram showing the value of FASE ₁ in comparison with the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine main body 2 ... Intake manifold 3 ... Fuel injection valve 5 ... Intake pipe 6 ... Air flow meter 7 ... Intake pipe pressure sensor 8 ... Crank angle sensor 9 ... Cooling water temperature sensor 20 ... ECU

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication F02D 45/00 301 F02D 45/00 301C (72) Inventor Michio Furuhashi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Toshinari Nagai 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Tadayuki Nagai 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72 Inventor Takashi Kawai 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Kenji Harima 1 Toyota Town Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Yuichi Goto Toyota, Aichi Prefecture 1 Toyota Town, Toyota City (72) Inventor Takayuki Otsuka Toyota Town, Toyota City, Aichi Prefecture Address Toyota Motor Co., Ltd. in

Claims (3)

[Claims] 1. An independent-injection-type internal combustion engine fuel injection timing control device for injecting fuel at an independent injection timing for each cylinder, comprising: operating state detecting means for detecting an operating state of the engine; Fuel injection timing setting means for setting the fuel injection timing in accordance with the operating state detected by the means, wherein the fuel injection timing setting means closes the fuel injection valve at least after the intake valve of the engine is opened. Changes in the operating state of the engine between the maximum lag injection timing set at, and the maximum early injection timing set to close the fuel injection valve at least before the intake valve of the engine opens. A fuel injection timing control device capable of continuously changing the injection timing according to the timing. 2. The method according to claim 1, wherein the operating state detecting means includes a warming-up degree detecting means for detecting a warming-up degree of the engine. 2. The fuel injection valve according to claim 1, wherein the lower the warm-up degree detected by the warm-up degree detecting means, the later the fuel injection valve is closed, and the higher the warm-up degree, the sooner the fuel injection valve is closed. Fuel injection timing control device. 3. The fuel injection timing setting device according to claim 1, wherein the operating state detecting device includes a cranking rotational speed detecting device that detects a cranking rotational speed when the engine is started. During the starting period, the fuel injection valve is closed later as the cranking speed detected by the cranking speed detector is lower, and the fuel injector is closed earlier as the cranking speed is higher. The fuel injection timing is set, and the fuel injection timing is shifted from the fuel injection timing at the start to the maximum earlier injection timing in accordance with an increase in the cranking rotational speed after the start. 2. The fuel injection timing control device according to claim 1.