JPH0143467Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] The present invention relates to a combustion chamber of a subchamber type engine.

[Conventional technology]

The combustion chamber of a conventional swirl chamber engine is shown in FIG. In the figure, the auxiliary combustion chamber 2 is recessed within the cylinder head 4. Further, the sub-combustion chamber 2 is located away from the cylinder center line B-B and near the cylinder 8. The shape of the sub-combustion chamber 2 may be hemispherical at the top, truncated conical at the bottom, or cylindrical.
FIG. 6 shows the lower part having a truncated cone. A fuel injection valve 5 and a glow plug 6 for preheating the inside of the auxiliary combustion chamber 2 at the time of starting the engine are installed in the auxiliary combustion chamber 2 as necessary. The auxiliary combustion chamber 2 communicates with the main combustion chamber 1, which is comprised of the top surface of the piston 7, the cylinder 8, and the lower surface of the cylinder head 4, via the auxiliary chamber nozzle 3.

During the compression stroke during engine operation, air in the main combustion chamber 1 is compressed by the piston 7, flows into the auxiliary combustion chamber 2 through the auxiliary chamber nozzle 3, and generates a vortex S. When fuel is injected from the fuel injection valve 5 along the direction of the vortex S, the fuel swirls in the sub-combustion chamber 2 together with the vortex S, and the fuel and air are mixed, ignited, and combusted.
The unburned fuel ejected from the sub-combustion chamber 2 is mixed with the air within the main combustion chamber 1 by gas ejected from the sub-combustion chamber 2. The jet flow flowing out from the sub-combustion chamber 2 reaches the wall of the cylinder 8 on the opposite side of the sub-combustion chamber 2 with respect to the cylinder centerline, and collides with the wall surface. After the collision, the particles disperse along the wall surface of the cylinder 8 wall.

In order to improve the formation and combustion of a mixture of fuel and air in the sub-combustion chamber 2 and the main combustion chamber 1, the jet velocity near the compression top dead center must be increased. Particularly in the main combustion chamber 1, the jet must reach the wall of the cylinder 8 in a short time.

In general, in the case of a small swirl chamber type engine, there is a structural limit to installing the auxiliary combustion chamber 2 closer to the center of the cylinder due to the arrangement of intake and exhaust valves, etc. Therefore, the passage area of the sub-chamber nozzle 3 is made smaller and the jet velocity is increased. As mentioned above, in order to improve the mixing and combustion of fuel and air in the combustion chamber, it is sufficient to increase the jet velocity near compression top dead center, but since the passage area of the pre-chamber nozzle 3 is fixed, The subchamber nozzle 3 is also throttled during periods other than this. Therefore, throttling loss and heat loss at the pre-chamber nozzle 3 increase, resulting in poor fuel efficiency and smoke emissions.

FIG. 5 shows a variable pre-chamber nozzle combustion chamber. The auxiliary combustion chamber 2 is located away from the cylinder center line B-B, and the protrusion 10 provided on the top surface of the piston 7 is inserted into the auxiliary chamber nozzle 3 provided on the auxiliary chamber mouthpiece 9 near compression top dead center. By doing so, the area of the nozzle in the subchamber is made small, and the area of the nozzle in the subchamber is large during other periods.

[Problem that the invention attempts to solve]

In this combustion chamber, when the protrusion 10 starts to be inserted into the sub-chamber nozzle 3 during the compression stroke, the sub-chamber nozzle area f becomes smaller as shown by the solid line in FIG. Although the jet velocity to 2 increases,
At this time, since the jet collides with the wall of the nozzle passage located away from the cylinder center line B-B in the sub-chamber nozzle 3, it is attenuated and the vortex S becomes difficult to form within the sub-combustion chamber 2. The mixing and combustion of fuel and air in the sub-combustion chamber 2 and therefore the mixing and combustion of fuel and air in the main combustion chamber 1 deteriorate.

[Means for solving problems]

The purpose of this invention is to improve the mixing and combustion of fuel and air in the auxiliary combustion chamber 2 and the main combustion chamber 1, reduce heat loss, and reduce the throttling loss of the auxiliary chamber nozzle 3 by focusing on the above points. , variable pre-chamber nozzle combustion that reduces the pre-chamber nozzle area near compression top dead center and improves gas flow characteristics in the sub-combustion chamber 2 and main combustion chamber 1, and increases the pre-chamber nozzle area outside of this period. The main feature of the combustion chamber is that the sub-combustion chamber provided with the sub-chamber nozzle is located away from the cylinder center line, and the sub-combustion chamber provided with the sub-chamber nozzle is located away from the cylinder center line, and when the piston is passing near the top dead center, the sub-combustion chamber is located within the sub-chamber nozzle. In a combustion chamber of a sub-combustion type engine in which a protrusion to be inserted is provided on the top surface of the piston, a notch is provided in the vicinity of the sub-combustion chamber side opening of the nozzle passage wall located away from the cylinder centerline.

[Effect]

By using the variable pre-chamber nozzle combustion chamber of the present invention, the pre-chamber nozzle area is narrowed at the critical period for mixing and combustion of fuel and air in the main and sub-combustion chambers, that is, near top dead center, and the notch allows for a good jet flow. and a vortex flow, and the area of the subchamber orifice can be increased in areas other than the vicinity of top dead center.

〔Example〕

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

FIG. 1 is a sectional view showing a combustion chamber of a first embodiment of the present invention.

In the figure, the auxiliary combustion chamber 2 is recessed within the cylinder head 4. Further, the sub-combustion chamber 2 is located away from the cylinder center line B-B and near the cylinder 8.

The shape of the auxiliary combustion chamber 2 may be a hemispherical upper part, a truncated conical lower part, or a cylindrical shape, and the lower part is a truncated conical one.

A fuel injection valve 5 and a glow plug 6 for preheating the inside of the auxiliary combustion chamber 2 at the time of starting the engine are installed in the auxiliary combustion chamber 2 as necessary.

The auxiliary combustion chamber 2 communicates with the main combustion chamber 1, which is comprised of the top surface of the piston 7, the cylinder 8, and the lower surface of the cylinder head 4, through a auxiliary chamber nozzle 3 provided in the auxiliary chamber mouthpiece 9.

A protrusion 10 is installed on the top surface of the piston 7, and when the piston is located near the top dead center, the protrusion 10 is inserted into the subchamber nozzle 3.

A notch 11 is provided in the sub-chamber nozzle 3 near the sub-combustion chamber side opening of the nozzle passage wall located away from the cylinder centerline BB. The notch 11 may have a straight shape, a curved shape (including a circular arc), or a combination of a straight line and a curved shape, but a straight shape is shown.

The operation in the case of the above configuration will be described.

With the variable pre-chamber nozzle combustion chamber according to the present invention, as shown by the solid line in Fig. 4, the pre-chamber nozzle area is large except near the top dead center of the compression stroke, so
The inflow speed of the gas in the main combustion chamber 1 into the auxiliary combustion chamber 2 caused by the compression of the gas in the main combustion chamber 1 is small, and when near the top dead center of the compression stroke, the piston 7
Since the protrusion 10 installed in the sub-chamber nozzle 3 is inserted into the sub-chamber nozzle 3 provided on the sub-chamber mouthpiece 9, the sub-chamber nozzle area f becomes small and the jet velocity from the main combustion chamber 1 to the sub-combustion chamber 2 increases. growing. At this time, since a notch 11 is provided in the sub-chamber nozzle 3 near the opening on the sub-combustion chamber side of the nozzle passage wall located away from the cylinder center line B-B, the jet J flows into the nozzle passage wall. Since the fuel flows into the sub-combustion chamber 2 without colliding with the fuel, the mixture and combustion of fuel and air within the sub-combustion chamber 2 are promoted to form a vortex S within the sub-combustion chamber 2 without attenuation. Ru.

In addition, in the expansion stroke, since the protrusion 10 is inserted into the sub-chamber nozzle 3 near the top dead center, the sub-chamber nozzle area f is small, and the gas in the sub-combustion chamber 2 flows into the main combustion chamber 1. Since the fuel is injected at high speed, mixing and combustion of the air and unburned fuel in the main combustion chamber 1 is promoted. As the piston, and thus the protrusion 10, further descends, the area f of the injection port in the sub-chamber increases, so that the residual gas in the sub-combustion chamber 2 easily flows out.

FIG. 2 is a sectional view showing a combustion chamber of a second embodiment of the present invention. Cylinder center line B of subchamber nozzle 3
This is the case when the angle α between the nozzle passage wall located away from -B and the cross section perpendicular to the sub-combustion chamber centerline A-A is larger than 90°.

In the first embodiment, the angle is 90°. The rest is the same as the first embodiment. Its operation is similar to that of the first embodiment.

FIG. 3 is a sectional view showing a combustion chamber of a third embodiment of the present invention. Cylinder center line B of subchamber nozzle 3
This is a case where the angle α between the nozzle passage wall located away from -B and the cross section perpendicular to the center line A-A of the sub-combustion chamber is smaller than 90°. The rest is the same as the first embodiment. The operation is similar to that of the first embodiment.

[Effect of idea]

Based on the above, when the variable pre-chamber nozzle combustion chamber of the present invention is used, the pre-chamber nozzle area is narrowed at the critical period for mixing and combustion of fuel and air in the main and sub-combustion chambers, that is, near top dead center, and the notch 11 is Because of this provision, a good jet flow and vortex flow can be formed, so that mixing and combustion of fuel and air can be promoted. Furthermore, since the pre-chamber nozzle area f can be increased in areas other than the vicinity of the top dead center, the throttling loss at the pre-chamber nozzle 3 and the heat loss within the combustion chamber can be reduced. Therefore, fuel efficiency and smoke emissions are improved, and engine noise and NOx can be reduced.

The effects are the same throughout the first to third embodiments.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a combustion chamber of a first embodiment of the present invention, FIG. 2 is a sectional view of a combustion chamber of a second embodiment, and FIG. 3 is a sectional view of a combustion chamber of a third embodiment. 4 is a line diagram showing changes in jet velocity and pre-chamber nozzle area, Fig. 5 is a sectional view showing a conventional variable pre-chamber nozzle combustion chamber, and Fig. 6 is a diagram showing combustion in a conventional swirl chamber engine. It is a sectional view showing a chamber. 1... Main combustion chamber, 2... Sub-combustion chamber, 3... Sub-chamber nozzle, 7... Piston, 8... Cylinder, 10...
...Protrusion, 11...Notch.

Claims (1)

[Scope of utility model registration request] A sub-chamber type in which a sub-combustion chamber equipped with a sub-chamber nozzle is located away from the cylinder center line, and a protrusion is provided on the top surface of the piston to be inserted into the sub-chamber nozzle while the piston passes near top dead center. A variable auxiliary chamber nozzle combustion chamber characterized in that a notch is provided near an opening on the auxiliary combustion chamber side of a nozzle passage wall located away from a cylinder centerline in a combustion chamber of an engine.