JPH0134657Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a combustion chamber of a pre-chamber type diesel engine.

1 and 2 relate to the combustion chamber of a conventional pre-chamber type diesel engine. In Fig. 1, 1 is the main combustion chamber, 2 is the sub-combustion chamber, 3 is the pre-chamber nozzle, 4 is the cylinder head, 5 is a fuel injection valve, 6 is a glow plug, 7 is a piston, and 8 is a cylinder.

The auxiliary combustion chamber 2 is recessed within the cylinder head 4,
The upper part can be hemispherical, and the lower part can be truncated conical or cylindrical. Figure 1 shows the lower part which is truncated conical. A fuel injection valve 5 is provided in the auxiliary combustion chamber 2, and a glow plug 6 is provided as necessary to preheat the inside of the auxiliary combustion chamber 2 to facilitate engine startup. The auxiliary combustion chamber 2 communicates with the main combustion chamber 1 formed by the top cylinder 8 of the piston 7 and the lower surface of the cylinder head 4 via the auxiliary chamber nozzle 3.

Next, the operation of the conventional device will be explained.

During the compression stroke during engine operation, the intake 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 along with the vortex S, the fuel and air are mixed, and ignited and burned. The semi-combusted air-fuel mixture ejected from the auxiliary combustion chamber 2 is mixed with the air in the main combustion chamber 1 in the auxiliary combustion chamber 2.
This is done by ejecting gas from the The jet flow flowing out from this auxiliary combustion chamber 2 is relative to the cylinder center line B-B.
It reaches the cylinder wall 8 on the opposite side from the sub-combustion chamber 2 and collides with the wall surface. After the collision, the particles disperse along the wall surface of the cylinder wall 8.

In order to improve the formation and combustion of the semi-combusted fuel-air mixture in the main combustion chamber 1, the jet must reach the cylinder wall 8 in a short time. For this reason, the passage area of the sub-chamber nozzle 3 is reduced to increase the jet velocity, so the throttling loss of the sub-chamber nozzle 3 and the heat loss in the main combustion chamber 1 are large. Since the jet penetration within the chamber 1 is increased, the passage area of the sub-chamber nozzle 3 can be increased. However, if the sub-chamber nozzle angle θ is made smaller in the conventional sub-chamber nozzle 3 as shown in Fig. 2,
Most of the ejected gas from the auxiliary combustion chamber 2 flows toward the cylinder center, and less gas flows toward the cylinder wall 8 on the auxiliary combustion chamber 2 side with respect to the cylinder center line B-B. Hatching part D
air utilization rate decreases. Also, when gas is ejected from the sub-combustion chamber 2 to the main combustion chamber 1, the angular difference (180-θ)° between the swirling direction of the vortex in the sub-combustion chamber 2 and the direction of gas ejection to the main combustion chamber 1 increases. Since the outflow of gas into the main combustion chamber 1 is suppressed, the subchamber nozzle throttling loss increases.

Conversely, if the sub-chamber nozzle angle θ is increased, gas flows out from the sub-combustion chamber 2 to the main combustion chamber 1 more easily, and the amount of gas flowing to the D portion of the main combustion chamber increases, but the jet flow toward the center of the cylinder increases. The problem is that the penetration is reduced, and the formation of a mixture of semi-burned fuel and air and combustion are deteriorated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a combustion chamber for a pre-chamber type diesel engine that solves the above-mentioned problems and improves combustion efficiency.

The combustion chamber of the auxiliary chamber type diesel engine according to the present invention has a relationship of θ ₁ <θ ₂ when the inflow angle to the main nozzle is θ ₂ and the outflow angle from the main nozzle is θ, and the auxiliary nozzle outlet is connected to the main nozzle. It is installed outside the main combustion chamber from the nozzle outlet, and the outflow angle from the auxiliary nozzle is θ ₁₁
The configuration is such that the above object is achieved by assuming the relationship θ ₁₁ >θ ₁ .

Embodiments of the combustion chamber of the pre-chamber type diesel engine according to the present invention will be described below with reference to FIGS. 3 to 8.

Here, the same or equivalent components as those of the conventional device will be described using the same reference numerals.

Figures 3 and 4 show the first embodiment of the present invention, and the structure of the auxiliary combustion chamber 2 has a hemispherical upper part and a truncated conical or cylindrical lower part. indicates the lower truncated cone. Further, the main nozzle 31 in FIG. 3 has an inflow angle of θ ₂ from the opening end of the auxiliary combustion chamber to the main nozzle 31, and an outflow angle of θ ₁ from the main nozzle 31 to the opening end of the main combustion chamber, then θ ₁ <θ ₂ , and the axis of the main nozzle 31 is configured as a curved shape (a combination of a circular arc and a straight line).

As the axis of the main nozzle 31, other arc shapes or polygonal lines can be considered.

The auxiliary nozzle 32 is located away from the main nozzle 31 outward from the cylinder center line BB. The outflow angle at the opening end from the auxiliary nozzle 32 to the main combustion chamber is θ ₁₁ , and the relationship θ ₁₁ >θ ₁ is established. FIG. 4 shows a linear passageway shape of the auxiliary nozzle 32 and an oval cross-sectional shape when viewed from the IV direction. Other possible cross-sectional shapes of the auxiliary nozzle 32 include a circular oval shape and the like.

Next, the operation of the first embodiment will be explained.

In the main nozzle 31 according to the present invention, since the angle θ ₂ is large, the angular difference (180 − θ ₂ ) between the swirling direction of the vortex in the auxiliary combustion chamber 2 and the direction of gas jetting into the main combustion chamber 1 becomes small, and the auxiliary The installation of the nozzle 32 facilitates gas outflow from the sub-combustion chamber 2 to the main combustion chamber 1. Furthermore, since the angle θ ₁ of the main injection port 31 is small, the penetration of the jet stream from the main combustion chamber 1 toward the center of the cylinder can be increased.

Further, by installing the auxiliary nozzle 32, gas flows also in the area in the direction of the cylinder wall on the side of the auxiliary combustion chamber 2 with respect to the cylinder center line BB, so that mixed combustion of the semi-combusted fuel and air in the main combustion chamber 1 can be promoted.

As described above, it is possible to improve fuel efficiency and smoke exhaust by reducing throttling loss at the pre-chamber nozzles 31 and 32 and promoting combustion, and it is also possible to achieve lower engine noise, higher speed, and improved startability of the engine.

FIG. 5 shows a second embodiment of the present invention. In the first embodiment, the outflow angle from the auxiliary nozzle 32 at the opening end of the main combustion chamber is set to θ ₁₁ , and
θ ₁₁ <θ ₂₁ (in the first embodiment _, θ ₁₁ =θ ₂₁ ).

Next, the operation and effect are almost the same as those of the first embodiment, but the outflow of gas from the sub-combustion chamber 2 to the main combustion chamber becomes easier, and the jet flow in the main combustion chamber 1 is directed toward the center of the cylinder. Shion can also be promoted further.

Note that the operation and effect are almost the same as in the first embodiment.

FIG. 6 shows a third embodiment of the present invention. In the first embodiment, the number of auxiliary nozzle holes 32 is plural (two in FIG.
). The operation and effect are almost the same as in the first embodiment.

As mentioned above, the combustion chamber of the subchamber type diesel engine of the present invention has a relationship such that θ ₁ <θ ₂ when the outflow angle from the main nozzle is θ ₁ and the inflow angle to the main nozzle is θ ₂ . Gas can easily flow into the main nozzle from the combustion chamber, and the venetration of the jet flow from the main nozzle to the main combustion chamber can be increased.

Next, the outlet of the auxiliary nozzle to the main combustion chamber is provided outward from the cylinder center line B-B with respect to the outlet of the main nozzle,
Furthermore, the outflow angle from the auxiliary nozzle to the main combustion chamber is θ ₁₁
Since the configuration is such that the relationship θ ₁₁ >θ ₁ holds when θ 11 >θ 1 , gas flows from the auxiliary nozzle to a region in the direction of the cylinder wall on the side of the auxiliary combustion chamber with respect to the cylinder center line BB. Therefore, by providing the main nozzle and the auxiliary nozzle as described above, it is possible to improve the combustion efficiency of the engine and improve fuel efficiency.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the main part of the conventional device, Fig. 2 is an explanatory diagram of the operation of the same device, Fig. 3 is a sectional view of the main part of the first embodiment of the present invention, and Fig. 4 is the arrow direction of Fig. 3. FIG. 5 is a second embodiment of the present invention, and FIG. 6 is a bottom view of the nozzle outlet portion of the third embodiment. 1...Main combustion chamber, 2...Sub-combustion chamber, 31...Main nozzle, 32...Auxiliary nozzle, θ1...Inflow angle to the main nozzle, _{θ2 ...} Outflow angle from the main nozzle, _θ11 ...Outflow angle from the auxiliary nozzle.

Claims (1)

[Scope of utility model registration request] In the auxiliary chamber nozzle, which is composed of a main nozzle and at least one auxiliary nozzle that communicate the main combustion chamber and the auxiliary combustion chamber, the outflow angle from the main nozzle to the main combustion chamber and the inflow angle from the auxiliary combustion chamber to the main nozzle When the angles are expressed as θ ₁ and θ ₂ with respect to a plane perpendicular to the center line A-A of the auxiliary combustion chamber, there is a relationship of θ ₁ <θ ₂ , and the auxiliary nozzle has an opening end toward the main combustion chamber. , cylinder center line B-
B, the main nozzle is located outside the main combustion chamber-side opening end of the main nozzle, and the sub-chamber-side opening ends of the main nozzle and the auxiliary nozzle are located in the same direction on one side of the sub-chamber center line; When the outflow angle from the auxiliary nozzle to the main combustion chamber is expressed by θ ₁₁ with respect to a plane perpendicular to the auxiliary combustion chamber center line A-A, θ ₁₁ is not 90° and has the relationship θ ₁₁ > θ ₁ . The combustion chamber of a pre-chamber type diesel engine.