JPH04303145A - Fuel controlling device for engine - Google Patents

Abstract

PURPOSE:To improve the starting performance for a multiple cylinder engine having a fuel injection valve for each cylinder. CONSTITUTION:An operating condition of a fuel injection valve installed to each cylinder of a first and a second bank is controlled by an ECU in such a way that a rich condition and a lean condition are repeated alternately for the air-fuel ratio of cylinders of which ignition orders are continuous in starting an engine corresponding to the ignition orders.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control system for an engine, and more particularly to a fuel control system for electronically controlling the amount of fuel injected from a fuel injection valve provided for each cylinder of a multi-cylinder engine.

0002

[Background Art] In order to achieve both output performance and fuel efficiency in engines for vehicles, etc., the amount of fuel injected from a fuel injection valve installed in the intake passage of the engine is adjusted to match the air-fuel mixture supplied to the combustion chamber. An electronically controlled fuel control device is sometimes installed to control the air-fuel ratio to the optimum air-fuel ratio depending on the operating condition of the engine, but even with this type of electronic fuel control device, the Fuel injection control that differs from the operating state is performed.

For example, Japanese Patent Laid-Open No. 57-206736 states that at the beginning of startup when there is little fuel adhering to the walls of the combustion chamber,
In order to shorten the starting period of the engine, fuel is injected according to a predetermined standard starting injection time so that the air-fuel ratio of the mixture supplied to the combustion chamber is in a rich state (a state in which the fuel is rich relative to the air). At the end of the startup period when the combustion chamber walls are wet with fuel, the air-fuel ratio of the air-fuel mixture is kept in a somewhat lean state (air A configuration of a fuel control device is shown in which the reference starting injection time is corrected to be reduced as the engine speed increases so that the fuel is in a lean state.

0004

[Problems to be Solved by the Invention] However, even in the prior art described in the above publication, the following problems may occur. In other words, when the engine starts, a large amount of current flows through the starter motor, which causes the power supply voltage of the fuel control device's electronic circuit to drop, making the operating state likely to become unstable.Furthermore, the engine speed fluctuates widely, making control reliable. Depending on the operating condition of the engine, for example, the amount of fuel loss may be too small, causing a misfire, resulting in poor starting conditions, or, conversely, the amount of fuel loss may be too large, causing a starting condition due to insufficient fuel. Otherwise, precise starting control may not be possible.

[0005] This invention addresses the above-mentioned problem when starting an engine equipped with an electronic fuel control device. Focusing on what you can control,
The purpose is to improve the starting performance of this type of engine.

[0006]

[Means for Solving the Problem] That is, a fuel control device for an engine according to the invention of claim 1 of the present application (hereinafter referred to as the first invention) has a plurality of cylinders and injects fuel to each cylinder. In an engine provided with a fuel injection means, the operation of the fuel injection means is controlled so that the air-fuel ratio of cylinders whose ignition order is consecutive when the engine is started is alternately repeated between a rich state and a lean state according to the ignition order. It is characterized in that it is provided with a control means.

[0007] Furthermore, the invention of claim 2 of the present application (hereinafter referred to as the second invention)
The fuel control device for an engine according to the present invention is a fuel injection system in which first and second banks each having a plurality of cylinders are arranged in a V-shape, and fuel is injected to each cylinder of the first and second banks. In an engine in which the ignition order is set such that each cylinder in both banks is ignited alternately, the air-fuel ratio of each cylinder belonging to the first bank becomes rich when the engine is started, and the so that the air-fuel ratio of each cylinder belonging to bank 2 is in a lean state.
The present invention is characterized in that a control means for controlling the operation of the fuel injection means is provided.

[0008] In the engine fuel control device according to the invention of claim 3 of the present application (hereinafter referred to as the third invention), the first and second banks each having a plurality of cylinders are arranged in a V-shape. In an engine that is provided with fuel injection means for injecting fuel into each cylinder in the first and second banks, and in which the ignition order is set so that each cylinder in both banks is ignited alternately, the engine starts. control means for controlling the operation of the fuel injection means so that the air-fuel ratio of each cylinder belonging to the first bank becomes a rich state and the air-fuel ratio of each cylinder belonging to a second bank becomes a lean state; The engine is characterized in that it is provided with a stop means for stopping the repeating rich and lean air-fuel ratio control according to the ignition order by the control means during idling operation.

[0009]

[Operation] That is, according to the first to third inventions, when the engine is started, the air-fuel ratio of the cylinders whose ignition order is consecutive is adjusted according to the ignition order of the fuel injected from the fuel injection means provided for each cylinder of the engine. Since the rich state and the lean state are controlled to be alternately repeated, the cylinder to which the rich air-fuel mixture is supplied is more likely to have an initial explosion, thereby shortening the starting period. In addition, if combustion continues in the cylinder to which a rich mixture is supplied after the first explosion, the required air-fuel ratio becomes lean due to the rise in engine temperature, making it easier to ignite even in the cylinder to which a lean mixture is supplied, resulting in combustion. Since this is carried out continuously in each cylinder, the engine rotation starts smoothly and reliable starting performance is obtained.

In particular, according to the second invention, the pair of banks is
In a V-type engine arranged in a V-type engine, after the cylinders in one bank are ignited, the cylinders in the other bank are ignited in a short time, so the inertia of the engine rotation due to the explosive force of the cylinder on the rich side is reduced. The air-fuel mixture in the lean cylinder is ignited without falling, which makes it easier to ignite the air-fuel mixture and further improves starting performance.

According to the third aspect of the invention, the air-fuel mixture is controlled to an appropriate air-fuel ratio in the idling state after startup, so the fuel consumption rate is reduced and deterioration in fuel efficiency is avoided. It turns out.

0012

[Embodiment] An embodiment in which the present invention is applied to a V-type six-cylinder engine will be described below.

As shown in FIG. 1, the engine 1 has first and second banks 1a and 1b each having three cylinders arranged in a V-shape, and a first bank 1a located on the left in the drawing. 1st, 3rd, and 5th cylinder #1, #3, #5 belonging to
Similarly, the second, fourth, and sixth cylinders #2, #4, and #6 belonging to the second bank 1b located on the right side of the drawing are, for example, the first cylinder #1, the second cylinder #2, The ignition order is set so that the third cylinder #3, the fourth cylinder #4, the fifth cylinder #5, and the sixth cylinder #6 are fired in this order. In other words, the first, third, and fifth cylinders #1, #3, # belong to the first bank 1a.
5, and the second, fourth, and sixth cylinders belonging to the second bank 1b #
The first and second banks 1a and 1b are provided with fuel injection valves 2...2 for each cylinder. , each fuel injection valve 2...2 is configured to inject fuel in accordance with a fuel injection signal from an electronically controlled control unit (hereinafter referred to as ECU) 3.

This ECU 3 receives a starter signal from a starter switch 4 that starts the engine 1, an engine rotation signal from an engine rotation sensor 5 that detects the engine rotation speed, and a compression top dead center at the beginning of the intake stroke for each cylinder. A cylinder identification signal from a cylinder identification sensor 6 that detects the position, an intake air amount signal from an air flow sensor 7 that detects the intake air amount of the engine 1, and a throttle sensor 8 that detects the opening degree of a throttle valve (not shown). A throttle signal, an air-fuel ratio signal from an air-fuel ratio sensor 9 installed at the exhaust pipe collection part (not shown) of the first bank 1a to detect the residual oxygen concentration contained in the exhaust gas, and a representative engine temperature. A water temperature signal from a water temperature sensor 10 that detects the temperature of engine cooling water is input, and the amount of fuel injected in each fuel injection valve 2 is controlled based on these signals.

[0015] Here, an outline of the fuel injection control performed by the ECU 3 will be explained. During normal operation after starting the engine, the EC
U3 calculates the intake air amount per intake stroke based on the engine rotation speed indicated by the engine rotation signal from the engine rotation sensor 5 and the intake air amount indicated by the intake air amount signal from the air flow sensor 7, and In addition to setting the corresponding basic injection time TP, this basic injection time TP is corrected using a feedback correction coefficient etc. determined according to the air-fuel ratio state indicated by the air-fuel ratio signal from the air-fuel ratio sensor 9, and furthermore, ineffective injection is performed. Finally, the normal injection time TI is calculated taking into account the time TV, and this normal injection time TI
A fuel injection signal corresponding to the fuel injection valve 2 is output to the fuel injection valve 2...2.

On the other hand, in this embodiment, the first bank 1
In order to make the air-fuel ratios of the first, third, and fifth cylinders #1, #3, and #5 in a to be richer than the stoichiometric air-fuel ratio at the time of starting, the starting injection time (hereinafter referred to as convenience) is set using the cooling water temperature TW as a parameter. The starting injection table for the first bank in which the starting injection time τ1 for the first bank is set, and the second, fourth, and sixth cylinders #2, #4, and #6 in the second bank 1b.
The starting injection time (hereinafter referred to as the starting injection time τ2 for the second bank for convenience) is set using the cooling water temperature TW as a parameter so that the air-fuel ratio of the second bank is leaner than the stoichiometric air-fuel ratio at the time of starting. Starting injection table and EC
It is stored in U3. Here, as shown in FIG. 2, the first bank starting injection time τ1 is set to become longer as the cooling water temperature TW becomes lower so as to promote combustibility during starting. Furthermore, as shown in FIG. 3, the starting injection time τ2 for the second bank is also determined by the cooling water temperature T.
It is set to become longer as W becomes lower. The starting injection time τ2 for the second bank is set to be relatively shorter than the starting injection time τ1 for the first bank under the same water temperature condition.

Then, the ECU 3 detects the cooling water temperature TW indicated by the water temperature signal from the water temperature sensor 10 when the engine 1 is started.
The fuel injection signal corresponding to the starting injection time τ1 for the first bank read from the starting injection table for the first bank is injected into each of the first, third, and fifth cylinders #1, #3, and #5. At the same time, a fuel injection signal corresponding to the second bank starting injection time τ2 read from the second starting injection table according to the cooling water temperature TW is output to the second, fourth, and sixth cylinders #. It outputs to each fuel injection valve 2, #4, #6...2.

Such fuel injection control is specifically shown in FIG.
This is done as follows according to the flowchart.

That is, the ECU 3 reads various signals in step S1, and then determines in step S2 whether the value of the start flag FS indicating the starting state of the engine 1 is 1 or not. This starting flag FS is set when the starter switch 4 is ON.
is set to 1 until the engine rotational speed NE reaches the predetermined starting judgment rotational speed N0, and the starter switch 4 is turned off or the engine rotational speed NE exceeds the predetermined starting judgment rotational speed N0. It is set to be reset when

When the ECU 3 determines that the start flag FS is set in step S2, the ECU 3 determines the start injection time τ1 and the start injection time for the first bank according to the cooling water temperature TW from the start injection tables for the first and second banks. Second
While reading out the bank starting injection time τ2,
Using the cylinder identification signal from the cylinder identification sensor 6 as a trigger, a fuel injection signal is output to each fuel injection valve 2...2 of the first and second banks 1a, 1b (steps S3 to S5).

Therefore, when each cylinder of the first bank 1a is in the intake stroke, as shown in FIGS. Injected synchronously, the second bank 1
When each cylinder in b is in the intake stroke,
), fuel corresponding to the second bank starting injection time τ2, which is shorter than the first bank starting injection time τ1, is injected in synchronization with the cylinder identification signal. As a result, the air-fuel ratio of the air-fuel mixture supplied to the first and second banks 1a and 1b alternately repeats rich and lean states.

On the other hand, when the ECU 3 determines that the start flag FS is not set in step S2 of the flowchart of FIG. It is determined whether the engine 1 is in an idling operating state based on the rotation signal, and when it is determined that the engine 1 is in an idling operating state, the process proceeds to step S7 to calculate the normal injection time TI for normal operation, and in step S5, the normal injection time TI for normal operation is calculated. A fuel injection signal corresponding to the injection time TI is output to each fuel injection valve 2...2. As a result, fuel that achieves the optimum air-fuel ratio according to the operating state of the engine 1 is injected from the fuel injection valves 2 for each cylinder.

Next, the operation of this embodiment will be explained using FIG. 6.

That is, starting injection is performed from time t1 when starting is started until engine speed NE rises to start determination speed N0. In that case, the first, third, and fifth cylinders #1, #3, #5 belonging to one first bank 1a
Since the air-fuel mixture in the second, fourth, and sixth cylinders #2, #4, and #6 belonging to the other second bank 1b become lean, the rich air-fuel mixture is supplied. The first detonation becomes easier in the first bank 1a, as indicated by the arrow (a) in Figure 6.
As shown in the figure, the first explosion occurs within a short time after starting.

[0025] After the first explosion, the engine rotation rapidly rises and reaches the start determination rotation speed N0 in a short time, and normal injection is performed from the time t2.

In the embodiment, a V-type engine has been described, but the present invention can also be easily applied to an in-line multi-cylinder engine. In that case, the amount of injection from the fuel injection valve provided in each cylinder is controlled so that the air-fuel ratio alternates between a rich state and a lean state for each cylinder in which the ignition order is consecutive.

[0027]

As described above, according to the present invention, when the fuel is injected from the fuel injection means provided for each cylinder of the engine, the air-fuel ratio of the cylinders whose ignition order is consecutive when the engine is started is adjusted according to the ignition order. Since the rich state and lean state are controlled to be alternately repeated, the cylinder to which rich air-fuel mixture is supplied is more likely to have an initial explosion, which shortens the starting period, and the rich air-fuel mixture is supplied to the cylinder after the initial explosion. If combustion continues in the cylinders to which fuel is supplied, the required air-fuel ratio becomes lean due to the rise in engine temperature, making it easier to ignite even in cylinders to which a lean mixture is supplied, and combustion continues in each cylinder. The engine rotation will start up smoothly and reliable starting performance will be obtained.

In particular, according to the second invention, the pair of banks is
In a V-type engine arranged in a V-type engine, after the cylinders in one bank are ignited, the cylinders in the other bank are ignited in a short time, so the inertia of the engine rotation due to the explosive force of the cylinder on the rich side is reduced. The air-fuel mixture in the lean cylinder is ignited without falling, which makes it easier to ignite the air-fuel mixture and further improves starting performance.

According to the third invention, the air-fuel mixture is controlled to an appropriate air-fuel ratio in the idling state after startup, so the fuel consumption rate is reduced and deterioration in fuel efficiency is avoided. It turns out.

[Brief explanation of the drawing]

FIG. 1 is a control system diagram of a V-type engine.

FIG. 2 is an explanatory diagram of a table showing a setting example of a first bank starting injection time used for fuel injection control.

FIG. 3 is an explanatory diagram of a table showing an example of setting a starting injection time for the first bank used for fuel injection control.

FIG. 4 is a flowchart showing fuel injection control.

FIG. 5 is a time chart showing the fuel injection state at startup.

FIG. 6 is a time chart showing changes in engine speed immediately after starting.

[Explanation of symbols]

1 Engine 1a 1st bank 1b 2nd bank 2 Fuel injection valve 3
ECU #1~#6 cylinder

Claims (3)

[Claims] Claim 1: In an engine that has a plurality of cylinders and is provided with fuel injection means for injecting fuel into each cylinder, the air-fuel ratio of the cylinders whose ignition order is consecutive at the time of starting the engine is set to a rich state according to the ignition order. 1. A fuel control device for an engine, comprising a control means for controlling the operation of the fuel injection means so that a lean state and a lean state are alternately repeated. 2. First and second banks each having a plurality of cylinders are arranged in a V-shape, and fuel injection means for injecting fuel to each cylinder of the first and second banks is provided. In an engine in which the firing order is set so that each cylinder in both banks is fired alternately, when the engine starts, the air-fuel ratio of each cylinder belonging to the first bank becomes rich, and the air-fuel ratio of each cylinder belonging to the second bank becomes rich. A fuel control device for an engine, comprising a control means for controlling the operation of the fuel injection means so that the air-fuel ratio is in a lean state. 3. First and second banks each having a plurality of cylinders are arranged in a V-shape, and fuel injection means for injecting fuel to each cylinder of the first and second banks is provided. In an engine in which the firing order is set so that each cylinder in both banks is fired alternately, when the engine starts, the air-fuel ratio of each cylinder belonging to the first bank becomes rich, and the air-fuel ratio of each cylinder belonging to the second bank becomes rich. A control means for controlling the operation of the fuel injection means so that the air-fuel ratio is in a lean state, and a control means for stopping repetitive control of rich and lean air-fuel ratios according to the ignition order by the control means during idling operation after startup. 1. A fuel control device for an engine, characterized in that a stopping means is provided.