JPH07107366B2 - Internal combustion engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to an internal combustion engine such as a diesel engine.

[Prior Art] Conventionally, in a diesel engine, which is a kind of internal combustion engine, as a combustion method, a direct injection method in which fuel is directly injected into a single main combustion chamber for combustion, A combustion chamber is provided, which has an injection port opened on the inner wall of the auxiliary combustion chamber, and fuel is injected into the auxiliary combustion chamber through the injection port from a fuel injection nozzle formed in a cylinder head following the injection port. There is a sub-combustion chamber system in which temporary combustion is performed. In particular, with the recent trend toward downsizing and speeding up of diesel engines, it is necessary to complete combustion in a shorter period of time, and therefore, those of a sub-combustion chamber system that are capable of high-speed combustion and have low noise are widely used.

The sub-combustion chamber in such a diesel engine has a lower half part of the sub-combustion chamber in which a through hole called a nozzle hole that communicates with the main combustion chamber is provided in a cylinder head that is usually provided with a cooling water passage above the main combustion chamber. The metal hot plug that composes is installed.

The hot plug installed in this way is equipped with a turbocharger as the diesel engine becomes smaller and faster, and is composed of high-grade heat-resistant alloys such as nickel and cobalt in terms of heat resistance and heat insulation. However, there is a problem of poor durability.

Also, since the auxiliary combustion chamber is made of metal, it has good thermal conductivity, and therefore the heat of the hot plug is conducted to the cylinder head cooled by the cooling water, and the temperature of the hot plug itself cannot be increased. The combustion gas in the combustion chamber is cooled by the wall surface, and the warm-up characteristics at the initial stage of engine start are extremely poor, which easily causes misfire.As a result, unburned gas such as HC is generated and combustion in the main combustion chamber occurs. However, there is a problem that smoke is generated due to inappropriateness, and there is a drawback that it is extremely expensive.

Therefore, as the heat load increases due to higher performance as described above,
By constructing the auxiliary combustion chamber, which has the highest temperature, with an inexpensive ceramic material such as silicon nitride, sialon, silicon carbide, zirconia, and lithia, which has high heat resistance and excellent heat insulation, the heat insulation and heat retention of the ceramic material As a result, cooling water loss is reduced, atomization of the injected fuel in the sub-combustion chamber is promoted, ignition delay of the air-fuel mixture is reduced, and its combustion is improved, and the amount of particulate emissions in exhaust gas is reduced. There is a proposal to do so.

Further, in order to improve the startability and the stability of combustion at low speed, a heating element is arranged in a part or the whole of the auxiliary combustion chamber to control combustion, and in order to further improve the combustion state, the auxiliary It has also been proposed to support a three-way catalyst on the inner surface of the combustion chamber to reduce the amount of harmful substances such as HC, CO and NOx generated.

[Problems to be solved by the invention]

However, if the auxiliary combustion chamber is made of ceramic material, many attempts have been made to improve the cross-sectional shape of the injection holes in order to improve the combustion and to improve the heat insulation effect of the ceramic material. It was difficult to improve the combustion over the entire combustion region in the complicated combustion situation of the diesel engine with the injection hole cross-sectional shape of the above, and the intended purpose could not be achieved.

Also, in order to improve the starting effect and the stability of combustion at low rotation speed, if a glow plug etc. is provided as a heating element in the auxiliary combustion chamber, in order to exert its effect better, the injected fuel should be a glow plug. It is desirable that the glow plug, etc. is projected into the auxiliary combustion chamber, that part of the inner wall of the auxiliary combustion chamber is spotted, and part or all of the glow plug, etc. is located in the spot facing portion. It is necessary to install it, and when the engine is not started or at low speed, the natural flow of vortices and the propagation of flames are obstructed, the combustion state deteriorates and smoke is easily generated, which is a major cause of output reduction. There was a problem that it also became. Further, it is technically extremely difficult to dispose a heating element in a part or the whole of the sub combustion chamber in order to control combustion.

Further, the one in which the three-way catalyst is carried on the inner surface of the auxiliary combustion chamber has a problem that the durability of the catalyst is poor.

[Means for solving problems]

In view of the above, the present invention has an injection hole member having a communication hole made of a ceramic material in order to provide an internal combustion engine with high output and low pollution by optimizing the amount of air flowing into the auxiliary combustion chamber and the strength of the vortex flow. And the auxiliary combustion chamber is made of a ceramic material, and the auxiliary combustion chamber lower chamber member is slidably mounted so that the opening cross-sectional area to the communication hole can be varied. Is.

〔Example〕

 Examples of the present invention will be specifically described below with reference to the drawings.

In the internal combustion engine shown in FIG. 1, a piston 1 has a main combustion chamber 2 formed therein, and a cylinder head 3 has a cooling water passage 4, a nozzle hole member 5 made of the ceramic material, and a sub combustion chamber made of the ceramic material. The chamber member 6 and the auxiliary combustion chamber lower chamber member 7 are mounted, and the auxiliary combustion chamber upper chamber member 6 is equipped with a fuel injection nozzle 11 via a glow plug 9 and an injection port 10. The injection hole member 5, the auxiliary combustion chamber upper chamber member 6 and the auxiliary combustion lower chamber member 7 are made of silicon nitride, sialon or the like as a ceramic material, and the auxiliary combustion chamber lower chamber member 7 slides on the cylinder head 3. The sliding shaft 12 is freely mounted and fixed to the sub combustion chamber lower chamber member 7 in the sliding direction.

On the other hand, when the sliding shaft 12 fixed to the sub-combustion chamber lower chamber member 7 is moved back and forth from the outside, the opening 13 formed in the sub-combustion chamber lower chamber member 7 is formed by the communication hole 14 formed in the injection hole member 5. The cross-sectional area of the opening 13 is variably controlled by appropriately shielding.

Further, the auxiliary combustion chamber lower chamber member 7, which is slidably attached to the cylinder head 3 so as not to impair the heat insulation effect, is injected through the seal ring 15 together with the injection hole member 5 and the auxiliary combustion chamber upper chamber member 6. The engine is assembled by mounting the cylinder head 3 in a recess of the cylinder head 3 which is set to be slightly larger than the outer diameter of the hole member 5, and mounting the cylinder head 3 on a cylinder block 17 via a head gasket 16.

In the sub-combustion chamber upper chamber member 6 and the sub-combustion chamber lower chamber member 7 for an internal combustion engine configured as described above, the amount of air flowing into the sub-combustion chamber 8 and the vortex flow of high-pressure air in the sub-combustion chamber 8 In order to control the strength of the engine, and further to control the combustion gas flowing out into the main combustion chamber 2, the sliding shaft 12 is moved forward and backward from the outside in response to the operation demand characteristics of the engine such as the engine load and rotation speed. Opening
The cross-sectional area of the opening 13 is variably controlled by appropriately blocking 13 with the communication hole 14 formed in the injection hole member 5, and for example, in the low rotation / no-load state, as shown in FIG. By minimizing the area, combustion stability at low speed and good startability are realized.

When the engine is partially loaded, the cross-sectional area of the opening 13 becomes small as shown in FIG. 3, and when the engine is fully loaded, a large amount of air flows in as shown in FIG. Since it is necessary to insert it, the cross-sectional area of the opening 13 is maximized so that an optimum combustion state can be realized according to the engine condition.

〔The invention's effect〕

As described above, according to the internal combustion engine of the present invention, the opening cross-sectional area can be variably controlled in response to the load and the rotational speed of the engine. It is possible to mix the high temperature, high pressure air with the injected fuel without damaging or disturbing it to produce a proper premixed mixture, which greatly improves the air utilization rate and ensures optimal combustion, resulting in smoke. Is reliably suppressed, which in turn significantly reduces the amount of particulate emissions in the exhaust gas to improve combustion efficiency and output loss, and also shortens the ignition delay time to reduce noise and heat load. And is a toxic substance as the maximum combustion temperature decreases.
It is possible to reduce the amount of NOx generated, and it is possible to obtain an internal combustion engine that is inexpensive and has a secondary combustion chamber suitable for mass production and that has high output and low pollution.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part showing a structure of an internal combustion engine according to an embodiment of the present invention, FIG. 2, FIG. 3, and FIG. 4 are views of a sub-combustion chamber lower chamber member in an internal combustion engine according to an embodiment of the present invention. It is a principal part bottom view for demonstrating the opening state which it has. 1 ... Piston 2 ... Main combustion chamber 3 ... Cylinder head 4 ... Cooling water channel 5 ... Injection hole member 6 ... Sub-combustion chamber upper chamber member 7 ... Sub-combustion chamber lower chamber member 8 ... Sub-combustion chamber 9 …… Glow plug 10 …… Injection port 11 …… Fuel injection nozzle 12 …… Sliding shaft 13 …… Opening 14 …… Communication hole 15 …… Seal ring 16 …… Head gasket 17 …… Cylinder block

Claims (1)

[Claims] 1. A sub combustion chamber of a diesel engine, a sub combustion chamber upper chamber member made of ceramic, a sub combustion chamber lower chamber member made of ceramic having an opening, and an injection hole member having a communication hole to the main combustion chamber. The sub-combustion chamber lower chamber member is slidably attached to the cylinder head, and the sub-combustion chamber lower chamber member is slid linearly in accordance with the required operation characteristics of the engine.
An internal combustion engine characterized in that the opening cross-sectional area is varied by adjusting the degree of overlap between the opening and the communication hole to control engine characteristics.