JPH05280346A - Controller for two cycle engine - Google Patents

Abstract

PURPOSE:To prevent unburnt components from blowing out to an exhaust system by installing an injector for injecting fuel and providing a controller for controlling an interval between a completed fuel injection time and an ignition time according to operating condition of an engine. CONSTITUTION:An injector 21 for injecting fuel is installed in the vicinity of an exhaust passage 18. An ignition plug 22 is installed on the upper part of a combustion chamber 7. A map showing relation between an engine/rotating speed and an intervals from a completed fuel injection time to ignition time is memories in a controller 23. Such a map is also memoried there as giving relation between an engine load shown by an acceleration opening and the abovementioned interval. The controller 23 outputs a signal to the injector 21 at a prescribed fuel injection timing according to a fuel pulse width so as to make the injector to inject fuel. It is thus possible to prevent unburnt components from blowing out to an exhaust system, and also prevent heat deterioration of a catalyst caused by after burning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for a two-cycle engine.

[0002]

2. Description of the Related Art Conventionally, various types of two-cycle engines have been proposed. (For example, JP-A-59-493
16, JP-A-59-79040, JP-A-62-11
3820, JP-A-63-248915, JP-A-64
-63617, JP-A-62-135655, etc.).

The two-cycle engine has an advantage that the engine can be made compact because the output ratio is large.

[0004]

[Problems to be Solved] However, it is more difficult for the two-cycle engine to secure stable combustibility as compared with the four-cycle engine. Further, in a two-cycle engine, since intake air and exhaust gas are scavenged simultaneously, the intake air may blow through to the exhaust side together with unburned fuel depending on how the intake air is introduced, which causes a problem that fuel efficiency is reduced. further,
When unburned components are introduced into the exhaust system, not only emission performance problems but also after-burn problems such as thermal deterioration of the catalyst are caused.

The present invention has been constructed in view of the above circumstances. By ensuring good combustion, it is possible to prevent blow-through of unburned components into the exhaust system and prevent thermal deterioration of the catalyst due to afterburn. It is an object of the present invention to provide a control device for a two-cycle engine that can perform

[0006]

In order to solve the above problems, the present invention is configured as follows. A means for determining the fuel injection amount according to the operating state, a fuel injection means for injecting fuel at a predetermined timing according to the determined fuel injection amount, and a mixture introduced into the combustion chamber at a predetermined timing. Ignition means for igniting, and timing control means for controlling the interval until the ignition by the ignition means after the fuel injection from the fuel injection means is ended according to the operating state, the timing control means is provided when the engine is rotating at high speed. It is characterized in that the ignition timing is controlled so as to reduce the interval from the end of fuel injection to the ignition timing.

The timing control means reduces the interval from the end of fuel injection to the ignition timing when the engine load is low. In a further preferred aspect, the timing control means controls the ignition timing so as to reduce the interval from the end of fuel injection to the ignition timing when the engine is running at high rotation and low load.

[0008]

In a two-cycle engine, intake and exhaust are performed simultaneously. Therefore, fuel injection is also performed in accordance with intake air. In this case, if fuel injection is early and ignition is late, the fuel may be discharged before it is completely burned. Further, if the fuel injection is delayed to ignite during the fuel injection, there is a problem that the ignitability deteriorates.

The relationship between the ignition timing and the fuel injection for obtaining good combustibility while preventing the blow-through of fuel differs depending on the operating state. In the present invention, control is performed so that the interval from the end of fuel injection to ignition is reduced at high engine speed and low engine load. At high engine speed, if the interval from the end of combustion to ignition is long, the flow velocity is high, so the injected fuel is diffused and the ignitability deteriorates, and unburned components may blow through. ..

Further, when the engine load is low, the above-mentioned interval is shortened because the air-fuel mixture in the combustion chamber is in a stratified state immediately after the end of fuel injection, and ignition is performed before the fuel mixture collapses, so that ignition occurs at low load. This is because the sex can be improved. Therefore, the combustibility can be improved as a whole.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. Referring to FIGS. 1 and 2, there is shown a schematic configuration of a two-cycle engine to which the present invention can be applied. The two-cycle engine 1 of this example has a uniflow type structure. A cylinder bore 2 is formed inside the engine 1, and a piston 3 is slidably arranged in the cylinder bore 2. The piston 3 is provided in the crank chamber 5 via a connecting rod 4, and is connected to a crankshaft 6 that extracts combustion energy as rotational power.

The upper space defined by the upper portion of the cylinder bore 2 of the engine 1 and the upper surface of the piston 3 constitutes a combustion chamber 7. An intake passage 8 is connected so as to communicate with the combustion chamber 7. Specifically, as shown in FIG. 2, the cylinder bore 2
A plurality of intake ports 9 are provided so as to be spaced apart from each other on the peripheral wall, and the 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 that supercharges intake air is provided further downstream. An intercooler 13 that cools the supercharged air is arranged 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 includes an intercooler 13 and a throttle valve 14.
It is provided in the area between and. The return passage 16 is provided with a bypass valve 17 for adjusting the return amount of supercharged air.

An exhaust passage 18 is provided above the combustion chamber 7.
Is connected to the opening, that is, the exhaust port 19,
An exhaust valve 20 is attached. The engine 1 of this example is of a cylinder injection type, and an injector 21 for injecting fuel is attached near the exhaust passage 18. Further, a spark plug 22 is attached to the upper part of the combustion chamber 7. In order to control the engine 1 of this example, a controller 23 preferably including a microcomputer is provided. The controller 23 includes an intake pressure sensor 2 for detecting an engine rotation signal from the distributor 24 and a pressure in the intake passage 18 provided downstream of the throttle valve 14.
5 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 17, and an ignition to the spark plug 22. Output a signal.

As described above, by controlling the opening degree of the throttle valve 14 and the opening degree of the bypass valve 17 by the controller 23, the supercharging pressure downstream of the throttle valve 14, that is, the intake pressure can be controlled. This intake pressure is applied to the combustion chamber 7
The amount of intake air introduced into is known. The amount of intake air and the intake pressure to the combustion chamber 7 have a great influence on the performance of the engine, that is, the combustion state, the output performance of the engine, the emission performance, and the like.

In this example, in view of the fact that the required performance of the engine 1 changes in accordance with the operating state of the engine, the supercharging pressure downstream of the throttle valve, that is, the combustion chamber 7 is introduced in accordance with the change in the engine load. It controls the intake pressure. In the control, the controller 23 first detects the engine speed, the depression amount of the accelerator pedal 26, that is, the accelerator opening degree, and the vehicle speed by inputting signals from various sensors.

Next, the controller 23 sets the target supercharging pressure according to the engine speed and the accelerator opening.
In this case, the controller 23 has a map created in advance corresponding to the engine speed and the accelerator opening, and sets the target supercharging pressure in light of this map. The controller 23 also stores a map showing the relationship between the engine speed and the interval from the end of fuel injection to ignition as shown in FIG. As shown in this map, the interval (crank angle) decreases as the engine speed increases.

Further, a map as shown in FIG. 4 which stores the relationship between the engine load indicated by the accelerator opening and the above interval is stored. The greater the engine load, the greater the spacing. The controller 23 reads the values of these maps and sets the fuel injection timing according to the engine speed and the engine load.

Then, the controller 23 controls the injector 2 at a predetermined fuel injection timing according to the fuel pulse width.
A signal is output to 1 for fuel injection.

[0019]

According to the above configuration of the present invention, the interval between the end of fuel injection and ignition is controlled according to the operating state of the engine, so that good ignitability is maintained regardless of changes in the operating state. You can In addition, it is possible to minimize blow-through of fuel, solve the problem of afterburn, and prevent deterioration of fuel consumption.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a two-cycle engine according to one embodiment of the present invention,

FIG. 2 is a structural diagram of an engine according to one embodiment of the present invention,

FIG. 3 is a graph showing the relationship between the end of fuel injection and ignition, and the engine speed.

FIG. 4 is a graph showing the relationship between the engine load and the interval between the end of fuel injection and ignition.

[Explanation of symbols]

 1 Engine 2 Cylinder Bore 3 Piston 4 Connecting Rod 5 Crank Chamber 6 Crank Shaft 7 Combustion Chamber 8 Intake Passage 9 Intake Port 10 Air Cleaner 11 Air Flow Meter 12 Supercharger 13 Intercooler 14 Throttle Valve 15 Surge Tank 16 Return Passage 17 Bypass Valve 18 Exhaust Passage 19 Exhaust port 20 Exhaust valve 21 Injector 22 Spark plug 23 Controller 24 Distributor 25 Intake pressure sensor 26 Accelerator pedal 27 Accelerator position sensor 28 Throttle actuator 29 Bypass valve actuator

Claims (3)

[Claims] 1. A means for determining a fuel injection amount according to an operating state, a fuel injection means for injecting fuel at a predetermined timing according to the determined fuel injection amount, and a fuel injection means for introducing the fuel into a combustion chamber at a predetermined timing. Ignition means for igniting the air-fuel mixture, and timing control means for controlling the interval until ignition by the ignition means after the fuel injection from the fuel injection means is completed according to the operating state, the timing control means comprising: A controller for a two-cycle engine, characterized in that ignition timing is controlled so as to reduce the interval from the end of fuel injection to the ignition timing when the engine is running at high speed. 2. A means for determining a fuel injection amount according to an operating state, a fuel injection means for injecting fuel at a predetermined timing according to the determined fuel injection amount, and a fuel injection means for introducing the fuel into a combustion chamber at a predetermined timing. Ignition means for igniting the air-fuel mixture, and timing control means for controlling the interval until ignition by the ignition means after the fuel injection from the fuel injection means is completed according to the operating state, the timing control means comprising: A control system for a two-cycle engine, characterized in that the ignition timing is controlled so as to reduce the interval from the end of fuel injection to the ignition timing when the engine load is low. 3. The control device for a two-cycle engine according to claim 1, wherein the timing control means controls the ignition timing so as to reduce the interval from the end of fuel injection to the ignition timing when the engine is running at high engine speed and low load.