JPS6018586Y2 - Sub-combustion chamber of sub-chamber diesel engine - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a subcombustion chamber of a subchamber type diesel engine that can be applied to a subchamber type diesel engine.

[Prior Art] In this type of pre-chamber type diesel engine, in order to sufficiently mix the fuel spray and air for complete combustion, a separate combustion chamber is provided to generate an active vortex flow within the main combustion chamber.
It uses a two-stage combustion method.

As shown in the conventional example in FIG. 1, a conventional pre-chamber type diesel engine is provided with a sub-combustion chamber formed by a rear member 10 and a front member 9 inserted into a cylinder head member 3. It is widely used that a front chamber 6 is provided on the rear shelf section 11 on the opposite side of the fuel injection valve 8 formed in the rear chamber 5 of the auxiliary combustion chamber, and in this case, the bottom of the front chamber 6 is is provided with a plurality of communication holes 7 that communicate with the main combustion chamber 4 provided at the top of the piston 2 in the cylinder liner 1, and
The front chamber 6
Generally, the center lines 6c of the two are eccentrically arranged so that they are different from each other.

However, in this auxiliary combustion chamber, the rear shelf 11 is wide and large, and the distance from the rear shelf 11 to the communication hole 7 is long, so the vortex generated in the rear shelf 11 and the fuel injection valve 8 There is a drawback that the flow of the unburned rich air-fuel mixture generated by the injected fuel into the main combustion chamber 4 is delayed, and its combustion is hindered.

As a result, the air utilization and mixture formation in the auxiliary combustion chamber are poor, and the engine's maximum output and fuel consumption rate are poor.
Furthermore, it is accompanied by a worsening of the exhaust color and an increase in engine noise.
Overall, this had the drawback of hindering improvements in engine performance.

Furthermore, the injection direction F of fuel into the auxiliary combustion chamber formed in this way is generally the same direction as or parallel to the center line 5c of the rear chamber 5, as shown in FIG. However, the disadvantage was that the air-fuel mixture could not be combusted properly.

[Purpose of invention]

The present invention was devised in view of the above-mentioned conventional circumstances and to eliminate these drawbacks, and it improves the air utilization and mixture formation in the sub-combustion chamber, and also improves the vortex flow of the mixture. The object of the present invention is to provide a sub-combustion chamber for a pre-chamber type diesel engine which can reduce the fuel consumption rate and improve overall engine performance by injecting fuel in the direction of the sub-combustion chamber.

[Structure of the idea]

The sub-combustion chamber of the sub-combustion chamber of the sub-chamber diesel engine of the present invention which achieves the above object has a front chamber provided on a rear shelf formed in the rear chamber, and a communication hole provided at the bottom of this front chamber communicating with the main combustion chamber. In the auxiliary combustion chamber, the center line of the rear chamber and the center line of the front chamber are eccentric, and the rear shelf is eccentric toward the center line of the rear chamber, and the rear shelf and the front chamber are arranged in a stepped shape. The present invention is characterized in that a shelf space communicating with the rear chamber is provided at one stage, and the injection direction of the fuel injection valve is directed toward the shelf of the shelf space facing downstream of the vortex generated in the rear chamber.

EXAMPLE Hereinafter, the present invention will be explained with reference to FIGS. 2 and 3, which show it as an example.

As shown in FIG.
It is formed by a rear shelf member 10 and a front member 9 inserted into the sub-combustion chamber, and a rear shelf part 11 formed in the rear chamber 5 of this sub-combustion chamber has a plurality of holes communicating with the main combustion chamber 4. Communication hole 7
A front chamber 6 is provided which has a bottom part thereof.

In the present invention, the center line 5C of the rear chamber 5 and the center line 6c of the front chamber 6 are made eccentric, and the rear shelf 11 formed in the rear chamber 5 has an eccentric center line 5C toward the rear chamber center line 5C. Rear shelf section 11
A shelf space 13 is provided which communicates the front chamber 6 with the front chamber 6 in a stepwise manner.
The shelf 12 of the shelf space 13 facing the downstream side of the vortex generated in
It is aimed at

That is, as shown in FIG. 2, another shelf 12 is provided on the main combustion chamber 4 side of the rear shelf 11 to form a shelf space 13.
3 is a shelf portion 1 that is eccentric from the center line 6c of the front chamber 6 by a distance l.
2 center line 12c, and this shelf 1
The center line 12c of the rear chamber 5 exceeds the center line 5C of the rear chamber 5.
Located on the side.

By forming this shelf space 13, the rear shelf 11 and the front chamber 6
The passage between the rear shelf section 11 and the front chamber 6 is reduced in a stepwise manner in the direction from the rear shelf section 11 to the front chamber 6.

Note that the centerline 12c of the shelf 12 can be located between the centerline 5c of the rear chamber 5 and the centerline 6c of the front chamber 6.

Then, the injection direction F of the fuel injection valve 8 mounted on the upper part of the rear member 10 in the cylinder head member 3 is changed to the vortex flow generated in the rear chamber 5 in the direction of the arrow during the compression stroke of the pre-chamber type diesel engine. It is oriented toward the 12th corner of the shelf facing the downstream side.

In this way, although the front chamber 6 of the auxiliary combustion chamber is eccentric to the rear chamber 5, there is a single shelf that communicates between the rear shelf 11 and the front chamber 6 in a stepped manner. By providing the partial space 13 eccentrically toward the rear chamber center line 5c side, it is possible to reduce the width of the rear shelf section 11 following the shelf section 12, and to generate turbulence in the vortex flow generated by the suction swirl. As a result, an unburnt rich mixture of fuel and air is formed well, and the distance from the stepped shelf 12 to the communication hole 7 is shortened, so that the mixture is not transferred to the main combustion chamber 4. Spillage can be done quickly.

Therefore, the rear shelf section 11 as in the conventional case is wide and large, and the distance from the upper rear shelf section 11 to the communication hole 7 becomes longer, so that the outflow of the unburned rich air-fuel mixture to the main combustion chamber 4 is delayed. This drawback can be overcome.

Furthermore, since the injection direction F of the fuel injection valve 8 is directed toward the corner of the shelf 12 facing the downstream side of the vortex, the fuel spray rides on the vortex and flows downward along the wall surface of the rear chamber 5. , ignites near the wall when it comes into contact with the high-temperature air flowing in from the front chamber 6, but when combustion occurs, the density in that area decreases, and the fuel gas is swirled into the center and at the same time The air is pushed outward and replaced with combustion gas, which improves the combustion in the sub-combustion chamber.At the same time, unburnt air-fuel mixture gathers in the front chamber 6 due to the vortex flow, causing ignition in the sub-combustion chamber. However, when combustion starts, the pressure in the auxiliary combustion chamber becomes higher than that in the main combustion chamber 4, and the unburnt air-fuel mixture is quickly injected into the main combustion chamber 4, so that it can be burned well in the main combustion chamber 4. can be done.

In particular, with the present invention, the fuel from the fuel injection valve 8 can be injected in a vortex flow, so the relative velocity between the air and the fuel is reduced, and the unburned air-fuel mixture before ignition is not blown away.
Since rapid combustion is not performed, the rate of pressure rise in the cylinder is low, which has the advantage of reducing engine combustion noise.

In other words, according to the present invention, the performance curve shown in FIG. 3 can be obtained.

Figure 3 shows a performance comparison curve obtained in an experiment comparing the sub-chamber type diesel engine with the sub-combustion chamber according to the present invention and the conventional sub-chamber type diesel engine with the sub-combustion chamber. In Fig. 3, the diagram Sd shown at the top has the output Ps on the horizontal axis and the exhaust color Sd on the vertical axis, and the diagram f shown at the bottom has the output Ps on the horizontal axis. The vertical axis represents the fuel consumption rate f (g/Psh).

The one-dot chain line in FIG. 3 is for the present invention, and the solid line is for the conventional example shown in FIG.

As shown in the diagrams in Fig. 3, these experiments have confirmed that the fuel consumption rate f and exhaust color Sd of the pre-combustion chamber type diesel engine according to the present invention are improved compared to the conventional ones. ing.

[Effect of idea]

In short, the auxiliary combustion chamber of the auxiliary chamber type diesel engine according to the present invention has a front chamber provided on the rear shelf formed in the rear chamber, and a communication hole provided at the bottom of this front chamber that communicates with the main combustion chamber. In the auxiliary combustion chamber, the center line of the rear chamber and the center line of the front chamber are eccentric, and the rear shelf is eccentric toward the center line of the rear chamber, and the rear shelf and the front chamber are arranged in a step-like manner. One stage of shelf space is provided that communicates with the auxiliary combustion chamber, and the injection direction of the fuel injection valve is directed toward the shelf of the shelf space facing downstream of the vortex generated in the rear chamber. Although it is eccentric to the rear chamber, the width of the rear shelf can be reduced by the one-step shelf space that communicates the rear shelf with the front chamber, and the suction swirl It is possible to generate turbulence in the mixture of the vortex and fuel that is generated,
This allows a rich, unburned mixture of fuel and air to form well, and allows the mixture to quickly flow out into the main combustion chamber.In addition, the injection direction of the fuel injection valve can be adjusted to Since it is directed toward the shelf of the space, the fuel from the fuel injector can be carried in a vortex, which promotes combustion and shortens the rear end, reducing fuel consumption and improving exhaust color. Karu.

Therefore, overall engine performance can be improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the main part of the sub-combustion chamber in a conventional example. Figures 2 and 3 show an embodiment of the present invention, in which Figure 2 is a longitudinal sectional view of the main part of the auxiliary combustion chamber, and Figure 3 shows the conventional example shown in Figure 1 and the present invention. It is a performance comparison diagram. 3... Cylinder head member, 4... Main combustion chamber, 5... Rear chamber, 5c... Center line of rear chamber, 6... ... Front chamber, 6c ... Center line of the front chamber, 7 ... Communication hole, 8 ... Fuel injection valve, 9 ... Front chamber member, 10... Rear chamber member, 11... Rear shelf, 12... Shelf, 12c... Center line of shelf, 13...・
・Shelf space, F... Injection direction.

Claims (1)

[Scope of utility model registration request] In the auxiliary combustion chamber, a front chamber is provided on a rear shelf formed in the rear chamber, and a communication hole provided at the bottom of the front chamber communicates with the main combustion chamber.1. The center line of the rear chamber and the center line of the front chamber are made eccentric, and the rear shelf section is provided with a shelf space that is eccentric toward the center line of the rear chamber and communicates the rear shelf section and the front chamber in a stepped manner. A sub-combustion chamber for a sub-chamber type diesel engine, characterized in that the injection direction of the fuel injection valve is directed toward a shelf of a shelf space facing downstream of a vortex generated in the rear chamber.