JP3148813B2 - Control device for high compression ratio engine for vaporized fuel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control apparatus for a high-compression-ratio engine for vaporized fuel, which burns volatile fuel at a high compression ratio.

[0002]

2. Description of the Related Art It has been known that the theoretical thermal efficiency of an internal combustion engine is increased by increasing the compression ratio of the fuel used. For this reason, in a diesel engine using light oil as a fuel, the compression ratio is set to about 20, and the fuel is injected into compressed air and burned to improve thermal efficiency.

[0003]

On the other hand, when a liquid fuel such as gasoline or methanol which is easily volatilized is subjected to in-cylinder injection such as a diesel engine, it is vaporized before generating an air-fuel mixture. However, there is a problem that the vaporized fuel and air cannot be sufficiently mixed.

Also, like a normal gasoline engine,
If a premixed air mixture of fuel and air is drawn into the cylinder, and high compression is applied, the temperature rises due to compression, which will cause early ignition and knocking, resulting in a higher compression ratio than before. Is difficult.

The present invention has been made in view of such a conventional problem, and provides an auxiliary combustion chamber provided with a control valve for burning a volatile fuel at a high compression ratio. It is an object of the present invention to provide a control device for a high-compression-ratio engine for vaporized fuel, which controls opening and closing of a control valve in accordance with a sub-combustion room temperature to improve fuel efficiency.

[0006]

According to the first aspect of the present invention, there is provided a control valve for opening and closing a connection □ between a sub-chamber for performing pre-combustion and a main chamber, and a control valve for controlling an inner wall temperature of the sub-chamber to a high temperature. Sub-room temperature holding means, a fuel injection nozzle for injecting easily volatile liquid fuel into the sub-chamber, an ignition plug provided in the sub-chamber and igniting the injected fuel, and setting the control valve to an engine load state. Control valve opening and closing control means for closing the control valve at the end of the expansion stroke when the engine is partially loaded, and closing the control valve at the full load when the engine is partially loaded. A control device for a high-compression-ratio engine for vaporized fuel, comprising: In the invention according to claim 2 of the present application, in the invention according to claim 1, the ignition operation of the ignition plug is suppressed based on the relationship between the load of the engine and the temperature of the sub-inner wall. A control device for a high compression ratio engine is provided.

[0007]

A control valve is mounted at a communication port between the sub-chamber and the main chamber for pre-combustion of the liquid fuel which is easy to volatilize, and the fuel is injected into the sub-chamber where the control valve is closed to control the sub-chamber wall temperature. The air-fuel mixture is activated and self-ignition is performed at the inner wall temperature. When the engine is partially loaded, the control valve is opened at the beginning of the expansion stroke, and when the control valve is closed at the end of the expansion, the remaining high-temperature exhaust gas remaining in the sub-chamber remains, so that the injected fuel can be activated in the next cycle. At full load, the control valve is closed during the exhaust stroke, but the exhaust pressure is high, so even if the valve is closed, high-temperature exhaust gas remains and can be activated for the next injected fuel. Efficient combustion can be performed as a specific engine.

[0008]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a control device for a high compression ratio engine for vaporized fuel according to the present invention.

In FIG. 1, reference numeral 1 denotes a cylinder, which is provided with a piston 2 which is slidable up and down. 4 are provided. And
A high-strength, heat-resistant ceramic is used for the piston head 21. The top of the piston head 21 is formed with a low inclined surface on the side of the sub-chamber 3, and a recess 22 is provided in a portion corresponding to the communication port 31 with the sub-chamber 3. It becomes an air reservoir and the piston 2
The main fuel chamber 23 is formed together with the upper gap of the main fuel chamber 23.

The sub-chamber 3 has a high strength such as silicon nitride, for example.
A heat-insulating air layer 32 is formed on the outer peripheral wall of the ceramic, and a control valve 5 that moves up and down to open and close the communication port 31 is attached to the center portion. The control valve 5 has a stem 51 supported by a shaft hole 33 in an upper wall portion, and a suction plate 52 attached to a top portion.
However, the opening / closing operation of the communication port 31 is performed by a suction force generated by controlling the power supply to the electromagnetic mechanism 34 above the sub chamber 3, and a heat shield 35 is disposed between the sub chamber 3 and the electromagnetic mechanism 34. I have.

Reference numeral 6 denotes an injection nozzle mounted on the side wall of the sub-chamber 3 for injecting easily volatilizable fuel from the injection pump 61 into the sub-chamber. Reference numeral 7 denotes an ignition plug for igniting the fuel by spark discharge. This is used when ignition is difficult due to the engine load or the internal temperature of the sub chamber 3.

Reference numeral 8 denotes a controller composed of a microcomputer, which includes an engine rotation sensor 81 and a load sensor 82.
When each detection signal from the crankshaft position sensor 83 is input, a predetermined calculation is performed, and the electromagnetic mechanism 34, the injection pump, the spark plug 7
For example, an operation command is issued.

FIG. 2 shows the crank angle in the present embodiment,
FIG. 3 and FIG. 4 are processing flow charts showing an example of the operation of the present embodiment.
Next, the operation of this embodiment will be described with reference to these drawings.

In step 1 in FIG. 3, first, an engine rotation signal from the rotation sensor 81, an engine load signal from the load sensor 82, and a position signal from the crankshaft position sensor 82 are input. If it is determined in step 2 that the engine has a partial load, the flow proceeds to step 3, and if the load is larger than the predetermined load La, the flow proceeds to step 15 in FIG.

In step 3, fuel injection and ignition timing are determined based on the stored map, and the routine proceeds to step 4, where fuel injection from the injection nozzle 6 is performed.

Next, if the judgment of the inner wall temperature of the sub-chamber 3 in step 5 is lower than the predetermined temperature Ta1, the operation proceeds to step 6 in which ignition is performed by the ignition plug 7 to start combustion in the sub-chamber. When the crank angle of the compression stroke reaches α ° (BTDC 30 ° to 0 °) near the top dead center, the control valve 4 is opened by the electromagnetic mechanism 34, and air is introduced from the main combustion chamber in the compression stroke. The fuel is burned and discharged into the main combustion chamber (step 8). Then, the crank angle in the next expansion stroke is θe (BBDC30 ° to ABDC
When the temperature reaches 20 °), the control valve 4 that is open is closed, and the engine is operated following the expansion stroke to the exhaust stroke (steps 9 and 10).

If the inner wall temperature of the sub-chamber 3 is high in step 5 above, the process proceeds to step 11, but since the temperature is high, self-ignition is performed in the sub-chamber and the crank angle becomes α ° near the top dead center. Is reached, the control valve 4 is opened, thereby performing the same operation as in the step 8 and thereafter (steps 12 to 14).

Step 1 shown in FIG. 4 when the engine load is large
When the process proceeds to step 5, the fuel injection and ignition timing are determined according to the load, and in the next step 16, the inner wall temperature of the sub chamber 3 is determined. When the temperature exceeds the predetermined temperature Ta2, the process proceeds to step 17, and in the case of the compression stroke, the fuel is injected from the injection nozzle 6 and ignited according to the inner wall temperature (step 18).

Next, at step 19, at a predetermined angle α2 ° near the top dead center, power is supplied to the electromagnetic mechanism 34 to control the control valve 5.
Is performed, and the control valve 5 is controlled to close at a predetermined angle θe1 in the exhaust stroke (steps 20 to 22). The valve closing timing in this case is set later than the valve closing timing at the time of the partial load as shown in FIG.

If the wall temperature of the sub-chamber 3 is low in step 16, fuel injection is performed by proceeding to steps 23 and 24. Since fuel does not self-ignite at low wall temperature, ignition is performed by the ignition plug 7 in step 25. Do.

Next, in step 19, α2
The control valve 5 is opened in step 27 at a time α3 ° which is shifted from the temperature by an angle α, and in the next step 28, the control valve 5 is closed at a predetermined angle θe2 in the exhaust stroke to close the engine. Operation will be continued.

[0023]

As described above in detail, according to the present invention, the sub-chamber for pre-combustion of easily volatilized fuel is provided with a heat shielding structure to increase the temperature of the inner wall and to provide a communication port between the main chamber and the main chamber. A control valve is attached and fuel is injected into the sub-chamber in which the control valve is closed to self-ignite at the inner wall temperature, or to ignite with a spark plug at low temperatures. The control valve opened before and after the top dead center of the piston according to the engine load causes the ignited air-fuel mixture in the sub-chamber to be blown out to the main chamber for combustion, and the control valve opened at the beginning of the expansion stroke. To
At the time of partial load, it closes at the end of the expansion stroke to store unburned high-temperature gas in the sub-chamber, vaporize and activate the fuel to be injected next, and at full load, the control valve is closed during the exhaust stroke. Even if the valve is closed due to high exhaust pressure, high temperature exhaust gas remains and vaporization and activation at the time of the next fuel injection are performed efficiently, and therefore, early ignition even when liquid fuel which is easily volatilized has a high compression ratio The effect is obtained that high-efficiency combustion is performed without causing knocking or knocking.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a control device for a high compression ratio engine for vaporized fuel according to the present invention.

FIG. 2 is a curve diagram showing a relationship between a crank angle and opening and closing of a control valve in the present embodiment.

FIG. 3 is a processing flowchart illustrating an example of the operation of the present embodiment.

FIG. 4 is a processing flowchart illustrating an example of the operation of the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylinder 2 ... Piston 3 ... Subchamber 5 ... Control valve 6 ... Injection nozzle 7 ... Spark plug 8 ... Controller 23 ... Main chamber 31 ... Communication port 32 ... Air layer 81 ... Rotation sensor 82 ... Load sensor 83 ... Crankshaft position Sensor

Claims (2)

(57) [Claims] 1. Communication between the pre-combustion sub chamber and the main chamber
A control valve that opens and closes, a sub-room temperature holding unit that keeps the inner wall temperature of the sub-chamber at a high temperature, a fuel injection nozzle that injects the easily volatile liquid fuel into the sub-chamber, and a fuel that is provided in the sub-chamber. The ignition plug and the control valve are opened at the beginning of the expansion stroke according to the load condition of the engine, and the control valve is closed at the end of the expansion stroke when the engine is partially loaded. A control device for a high compression ratio engine for vaporized fuel, comprising: control valve opening / closing control means for closing a control valve in a stroke. 2. The control device for a high compression ratio engine for a vaporized fuel according to claim 1, wherein the ignition operation of the ignition plug is suppressed based on a relation between an engine load and a sub-inner wall temperature.