JPH06101553A - Injection timing control device of engine - Google Patents

Abstract

PURPOSE:To prevent the blowby of fuel into an exhaust port while securing the time required for fuel to be mixed with fresh air through vaporization and atomization by setting fuel injection starting time in the vicinity of exhaust-port closing time if acceleration is detected. CONSTITUTION:While an engine is running, a controller 23 detects signals detected by an air flow sensor 11, a distributor 24, an intake pressure sensor 25 and an accelerator position sensor 27, thereby determining whether or not the engine 1 is being accelerated. When the engine is recognized as being accelerated, ignition timing is corrected by a predetermined value corresponding to the degree of aceleration so as to be advanced with respect to engine speed, and a limit value for the delay of injection starting time with respect to engine speed is computed from engine speed and on the basis of a predetermined diagram, and a fuel injection quantity and an injection starting time that correspond to the running condition are computed. When the injection starting time obtained exceeds the limit value for the delay with respect to engine speed, the limit value for the delay with respect to engine speed is used, while when the injection starting time is advanced with respect to engine speed, the infection starting time obtained is selected, so as to prevent the blowby of fuel during an overlap period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine fuel injection timing control device.

[0002]

2. Description of the Related Art Conventionally, as a blow-through preventing means for a two-cycle engine, an in-cylinder direct injection type two-cycle engine has been proposed in which a fuel injection valve is oriented in a combustion chamber formed in a cylinder so that fuel is directly injected into the combustion chamber. It has been. Generally, in a 2-cycle engine, the overlap period in which both the intake port and the exhaust port are opened is longer than that in a 4-cycle engine. Is discharged from the exhaust port, which causes a problem of deterioration of fuel efficiency and an increase in the amount of unburned fuel, that is, HC, which is one of the harmful components in the exhaust gas. There is one that avoids the above problem by supplying only air that does not contain fuel to perform scavenging and then starting fuel injection from the fuel injection valve after closing the exhaust port.

For example, according to Japanese Unexamined Patent Publication No. 62-113820, exhaust gas accumulated in the lower part of the combustion chamber and fresh air sucked in the upper part of the combustion chamber by ending the fuel injection end at the beginning of the compression stroke of the engine. By supplying the fuel in the vicinity of the boundary line between the fuel cell and the fuel cell, it is intended to promote the vaporization and atomization of the fuel by the heat of the exhaust gas, while promoting the mixing of the fresh air and the fuel.

Further, according to Japanese Patent Application Laid-Open No. 4-78004, the fuel injection end timing is brought closer to the ignition plug ignition timing as the engine speed increases toward the high speed side, so that the fuel blow-through to the exhaust port is prevented. There are those that prevent it and avoid afterburn, which is one of the causes of catalyst deterioration.

[0005]

However, by setting the fuel injection end timing at the beginning of the compression stroke of the engine in the operating region where the fuel injection amount increases, fuel injection is also performed during the overlap period, and It is required to conflict with the promotion of mixing with fresh air by vaporization and atomization of the fuel and the prevention of blow-through of fuel to the exhaust port.

The present invention is constructed in view of the above circumstances, and prevents the blowout of the fuel injection start timing to the exhaust port while ensuring the mixing time with the fresh air due to the vaporization and atomization of the fuel. The purpose is to achieve both.

[0007]

[Means for Solving the Problems] Means for constructing the present invention in order to solve the above problems are as follows.

According to the structure of claim 1, a fuel injection valve for directly injecting fuel into a combustion chamber formed in a cylinder, an engine speed detecting means, a throttle opening detecting means, and an engine water temperature detecting means. And the engine speed detected from each of the detection means, the throttle opening,
In a fuel injection timing control device for an engine, which comprises fuel control means for controlling a fuel injection amount injected from a fuel injection valve according to an engine water temperature,

An engine acceleration detecting means and a valve closing timing detecting means for detecting an exhaust port closing timing when the exhaust port is closed by an exhaust valve or a piston are provided, and fuel injection is performed when acceleration is detected by the acceleration detecting means. An injection start control means for setting a start timing near the exhaust port closing timing is provided.

According to the second aspect of the present invention, the steady state detecting means for detecting that the operating state of the engine is a steady state, the acceleration detecting means for detecting that the operating state of the engine is an accelerating state, and the engine First injection start timing limiting means for setting a limit value of the fuel injection start timing to the delay side in the engine rotation direction according to the engine speed when the operating condition is steady, and the first injection when the engine operating condition is accelerated. The second injection start timing limiting means for setting a limit value of the fuel injection start timing on the advancing side in the engine rotation direction with respect to the start timing limiting means.

[0011]

In the in-cylinder direct injection type two-cycle engine, the overlap period in which both the intake port and the exhaust port are opened in order to scaveng the exhaust gas in the combustion chamber with fresh air is set longer than that in the four-cycle engine. In this case, if the fuel injection start timing is set to this overlap period, the fuel injected from the fuel injection valve will be entrained in the scavenging flow and discharged as unburned fuel from the exhaust port, resulting in deterioration of fuel efficiency and exhaust gas emission. There is a problem that leads to an increase in HC, which is one of the harmful components.

Further, by delaying the fuel injection start timing so as to avoid the overlap period, the vaporization / atomization time of the fuel injected from the fuel injection valve is shortened when the engine speed is high, resulting in incompleteness. There is a problem that the output is reduced by combustion and the emission amount of harmful components in the exhaust gas is increased. Therefore,

According to the first aspect of the invention, the acceleration state of the engine is detected, and when the acceleration is detected, the fuel injection start timing is determined with respect to the exhaust port closing timing, so that the blow-through fuel during the overlap period is accelerated. By avoiding the problem of increasing fuel consumption, we are improving fuel efficiency and reducing the emission of harmful components in exhaust gas.

According to the second aspect of the present invention, the engine is accelerated while the first injection start timing limiting means is provided for setting the limit value of the fuel injection start timing to the delay side in the engine rotation direction according to the engine speed. A second injection start timing limiting means for setting a limit value for the fuel injection start timing is provided on the advance side of the first injection start timing limiting means in the engine rotation direction. The first injection start timing limiting means selects the fuel injection start timing according to the rotational speed to avoid the overlap period, and the second injection start timing limiting means increases the intake flow rate during acceleration as compared with the steady state. In order to improve the scavenging ability, the fuel injection start timing is delayed compared to the steady state, and the optimum fuel injection start timing is selected according to the operating condition to prevent fuel blow-through during the overlap period and promote mixture mixing. It is compatible with both.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic structure of a cylinder direct injection type two-cycle engine to which the present invention can be applied.

The two-stroke engine 1 of this embodiment includes a cylinder bore 2, a piston 3, a connecting rod 4, a crank chamber 5, a crankshaft 6, a combustion chamber 7, and an intake passage 8.
An intake port 9, an air cleaner 10, an air flow meter 11, a supercharger 12, an intercooler 13, a throttle valve 14, a surge tank 15, a return passage 16, a bypass valve 17, and an exhaust passage 18. , The exhaust port 19, the exhaust valve 20, the injector 21, the spark plug 22, the controller 23, the distributor 24, the intake pressure sensor 25, and the accelerator pedal 26.
, An accelerator position sensor 27, a first actuator 28, and a second actuator 29.

The two-cycle engine of this example has a uniflow type structure, and a cylinder bore 2 is formed inside thereof. A piston 3 is slidably arranged in the cylinder bore 2, the piston 3 is provided in a crank chamber 5 via a connecting rod 4, and is connected to a crankshaft 6 for taking out combustion energy as rotational power.

The upper space formed by the upper portion of the cylinder bore 2 of the engine 1 and the upper surface of the piston 3 is a combustion chamber 7, and an intake passage 8 is connected so as to communicate with the combustion chamber 7. Specifically, as shown in FIG. 2, a plurality of intake ports 9 are provided on the peripheral wall of the cylinder bore 2 so as to be spaced apart from each other, and intake air is introduced into the combustion chamber 7 substantially uniformly over the entire circumference. An air cleaner 10 is arranged at the tip of the intake passage 8, that is, at the most upstream side, and an air flow meter 11 for detecting the amount of intake air is provided downstream thereof.

A supercharger 12 for supercharging intake air is provided further downstream. An intercooler 13 that cools the supercharger 12 is disposed downstream of the supercharger 12, a throttle valve 14 is provided downstream thereof, and a surge tank 15 is provided further downstream to form an intake system. Further, in the configuration of this example, the return passage 16 for returning the excess supercharged air to the upstream side of the supercharger 12 is provided. The take-out portion of the return passage 16 is provided in a portion between the intercooler 13 and the throttle valve 14. The return passage 16 is provided with a bypass valve 17 for adjusting the return amount of supercharged air.

An exhaust passage 18 is connected to the upper portion of the combustion chamber 7, and an exhaust valve 20 is attached to an exhaust port 19 which is an opening of the exhaust passage 18. The engine 1 of this example is a direct injection type cylinder, and an injector 21 for injecting fuel into the combustion chamber and an ignition plug 22 are attached near the exhaust passage.

In order to control the engine 1 of this example,
Controller 2 composed of a microcomputer
3 is provided. The controller 23 includes an engine rotation signal from the distributor 24 and a throttle valve 1
A signal from an intake pressure sensor 25 that detects the pressure in the intake passage 18 and a signal from an accelerator position sensor 27 that detects the amount of depression of the accelerator pedal 26 are input. The controller 23 performs a predetermined calculation based on these signals, and outputs a throttle opening signal to the actuator 28 of the throttle valve 14, a bypass opening signal to the actuator 29 of the bypass valve, and ignition to the spark plug 22. Output a signal.

FIG. 3 is a schematic diagram showing the opening / closing valve timing of the intake port and the exhaust port with respect to the rotation angle of the crankshaft 6 obtained by detecting the signal from the distributor 24. The point at the apex of the circle shown in FIG. 3 indicates that the piston 3 is at the top dead center position (TDC) of the cylinder bore 2, and the point at the bottom of the circle is the bottom dead center position of the piston 3 ( B.D.C.). Here, the exhaust port valve opening timing EO and the intake port valve opening timing I are sequentially arranged with respect to the advance side of the engine rotation direction.
O, exhaust port closing timing EC, and intake port closing timing IC are set respectively.

When the operating condition of the engine is steady, a limit value is set on the delay side of the exhaust port closing timing EC with respect to the engine rotation direction, and fuel injection is performed only on the advance side of the engine rotation direction from the delay side limit value. The start time is set. Considering the distance from the injector 21 to the exhaust port 19, there is a time delay from the time when the fuel injected from the injector 21 is drawn into the fresh air flowing into the intake port 9 until it flows into the exhaust port 19,
This is because even if the fuel injection start timing is set to the delay side by this time delay, blow-through does not occur during the overlap period. Further, as the engine speed increases, the flow velocity of fresh air flowing from the intake port 9 increases, so that the injector 2
Since the time delay from 1 to the flow of fuel into the exhaust port 19 becomes short, the delay side limit value is corrected to the advance side in the engine rotation direction as the engine speed increases, as shown in FIG. Further, when the engine speed is high, the gas exchange time is shortened and the exhaust gas scavenging efficiency is reduced.Therefore, the time delay of blow-through to the exhaust port due to the increase in the engine speed at high speed does not change much. Therefore, when the engine speed reaches a predetermined speed or more, the
As shown in (4), the delay side limit value represented as the delay control value α ° is reduced by a correction ratio to the advance side, or the delay side limit value at the time of the predetermined rotation is maintained, regardless of the engine speed. In addition to ensuring the time for fuel to vaporize and atomize, to secure combustion stability and output, and to prevent HC blow-through during the overlap period, increase HC emissions in exhaust gas components and change the air-fuel ratio to the rich side. It is possible to prevent an increase in Nox and Co emissions in the exhaust gas due to the above.

When the operating condition of the engine is in transition, the throttle valve opening with respect to the engine speed is large, so the flow velocity of the fresh air flowing from the intake port 9 increases and the air-fuel ratio around the spark plug becomes leaner than the theoretical air-fuel ratio. The air-fuel ratio is corrected to a richer side than the stoichiometric air-fuel ratio in order to prevent a lean spike, which is a misfire that occurs as a result, and therefore, as shown in FIGS. It is corrected to the leading side of the rotation direction. Here, FIG. 5 is a diagram showing a delay side limit value of the fuel injection start timing in the engine rotation direction according to the engine speed, and in the diagram for acceleration in FIG. 5, it is obtained by the acceleration detecting means. The amount of correction to the leading side of the above diagram is increased according to the magnitude of acceleration. Here, the fuel injection start timing is shown in FIG.
Is selected in accordance with the operating state only above the shaded portion of the line, and the start of fuel injection in the shaded portion is prohibited.

FIG. 6 is a control flow chart relating to the fuel injection signal of the injector 21. The controller 23 detects signals detected by the air flow sensor 11, the distributor 24, the intake pressure sensor 25, and the accelerator position sensor 27 in order to determine the operating state of the engine in S1. In S2 and S3, it is determined whether the operating state of the engine is in an accelerating state, and in the steady state, the diagram for the steady state in FIG. 5 and when the acceleration is determined, the line in the steady state in FIG. 5 according to the magnitude of acceleration. With the diagram for acceleration shown in FIG. 5, which is obtained by correcting the diagram to the advance side of the engine rotation direction by a predetermined value or reading the mapped diagram for acceleration from the storage device in the controller 23. You have selected one of the diagrams. In S4, the engine rotation direction delay side limit value of the fuel injection start timing is calculated from the engine speed obtained in S1 based on the diagram of FIG. 5 selected in S2 and S3. In S5, the fuel injection amount and the fuel injection start timing according to the engine operating state obtained in S1 are obtained. In S6, if the fuel injection start timing obtained in S5 is on the delay side of the engine speed from the delay side limit value determined in S4, S7 is executed in S7.
4 is used, or when the fuel injection start timing obtained in S5 is on the advance side of the engine speed from the delay side limit value determined in S4, it is obtained in S5 in S8. By selecting the fuel injection start timing, the time required for forming the air-fuel mixture is secured while preventing the fuel blow-through during the overlap period.

By providing a changing means for changing the intake / exhaust timing and closing the intake port earlier than the exhaust port at least at low speed and low load, the residual amount of exhaust gas remaining in the combustion chamber, that is, the dilution gas is reduced. Combustion stability can be secured.

[0027]

According to the present invention, the engine operating condition is such that a limit value is provided on the delay side in the engine rotation direction at the fuel injection start timing so as not to cause fuel blow-through in the overlap period of the direct injection type two-cycle engine. By changing the delay side limit value according to the engine speed and the magnitude of engine acceleration, regardless of the operating state of the engine, reducing the amount of harmful components in exhaust gas by preventing fuel blow-through,
This ensures both combustion stability of the engine.
That is,

According to the first aspect of the present invention, when acceleration is detected, the fuel injection start timing is determined with respect to the exhaust port closing timing to reduce or prevent fuel blow-through during the overlap period between the intake port and the exhaust port. Can be improved. This is because the cleaning effect of the catalyst such as the three-way catalyst that cleans the exhaust gas is greatly reduced at the time of acceleration when the air-fuel ratio is set to a rich level, so fuel blow-through during the overlap period between the intake port and the exhaust port is reduced. This is because it becomes a particular problem and has a high effect on cleaning exhaust gas at the time of acceleration.

According to the second aspect of the present invention, when the engine is operating normally, fuel injection is started earlier than during acceleration, and when the engine is operating, fuel vaporization / atomization time is secured to improve fuel efficiency and stabilize combustion. It is intended to improve the exhaust purification performance of the catalyst at the same time as ensuring the property.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a direct fuel injection two-cycle engine to which the present application can be applied.

FIG. 2 is a schematic diagram of a combustion chamber of a direct fuel injection type two-cycle engine.

FIG. 3 is a schematic diagram illustrating opening / closing valve timings of an intake port and an exhaust port with respect to a rotation angle of a crankshaft 6 and a fuel injection start timing in a steady state.

FIG. 4 is a schematic diagram illustrating opening / closing valve timings of an intake port and an exhaust port with respect to a rotation angle of a crankshaft 6 and a fuel injection start timing during acceleration.

FIG. 5 is a diagram showing a delay side limit value in the engine rotation direction of the fuel injection start timing according to the engine speed.

FIG. 6 is a control flowchart of the fuel injection start timing according to the fuel injection start timing of the engine.

[Explanation of symbols]

2-cycle engine ... 1, cylinder bore ... 2, piston ... 3, connecting rod ... 4, crank chamber ... 5, crankshaft ... 6, combustion chamber ... 7, intake passage ... 8, intake port ...
9, air cleaner ... 10, air flow meter ... 11, supercharger ... 12, intercooler ... 13, throttle valve ...
14, surge tank ... 15, return passage ... 16, bypass valve ... 17, exhaust passage ... 18, exhaust port ... 19, exhaust valve ... 20, injector ... 21, spark plug ... 22,
Controller ... 23, Distributor ... 24, Intake pressure sensor ... 25, Accelerator pedal ... 26, Accelerator position sensor ... 27, First actuator ... 28, Second
Actuator ... 29

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shigeru Sakurai No. 3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Takehiko Yasuoka No. 3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Corporation Within

Claims (2)

[Claims] 1. A fuel injection valve for directly injecting fuel into a combustion chamber formed in a cylinder, an engine speed detecting means, a throttle opening detecting means, and an engine water temperature detecting means. In a fuel injection timing control device for an engine, which comprises fuel control means for controlling a fuel injection amount injected from a fuel injection valve in accordance with an engine speed, a throttle opening, and an engine water temperature detected from An acceleration detecting means and a valve closing timing detecting means for detecting an exhaust port closing timing when the exhaust port is closed by an exhaust valve or a piston are provided. When acceleration is detected by the acceleration detecting means, a fuel injection start timing is set to the exhaust port. A fuel injection timing control device for an engine, comprising: an injection start control means that is set near a valve closing timing. 2. A steady state detecting means for detecting that the operating state of the engine is a steady state, an acceleration detecting means for detecting that the operating state of the engine is an accelerating state, and an engine rotation when the operating state of the engine is steady. A first injection start timing limiting means for setting a limit value of the fuel injection start timing to the delay side of the engine rotation direction according to the number of the engine, and the engine rotation by the first injection start timing limiting means when the operating condition of the engine is accelerated. 2. The fuel injection timing control device for an engine according to claim 1, further comprising: a second injection start timing limiting unit that sets a limit value for the fuel injection start timing on the leading side of the direction.