JPS63314312A - Internal combustion engine - Google Patents

Abstract

PURPOSE:To enlarge the swirling range of a swirl as well as to uniformize the distribution of an air-fuel mixture by setting up a projection, overhanging inward a combustion chamber, in a wall surface of the combustion chamber, and thereby forming a collecting space of ignition fuel and a swirl passage each in both upper and lower parts inside the combustion chamber. CONSTITUTION:A square combustion chamber 2 is formed in a piston head 1. On the other hand, in a cylinder head 3, a fuel injection nozzle 5 is set up in a mounting hole 4 as adjoining the combustion chamber 2. And, this fuel injection nozzle 5 sprays sub-fuel spray F1 out of a sub-nozzle 9 at a low load area, while it sprays main fuel spray F2 out of a main nozzle 7 at a medium- high area. In this constitution, in the inner part of the combustion chamber 2 where a swirl S whirls, there is provided with a projection 14 of a lip form or the like overhanging inward the central part in a height direction of the wall surface 2b. And, a collecting space D for collecting the sub-fuel spray F1 is formed in the upper part of this projection 14. In addition, a swirl passage P for making the swirl S run past is formed in the lower part of this collecting space D.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application J] The present invention relates to an internal combustion engine, and particularly to an internal combustion engine suitable for applying low cetane number fuel to a diesel combustion system.

[Prior Art] Generally, a diesel internal combustion engine is configured as a spark ignition internal combustion engine when alcohol, gasoline, or the like having an extremely low cetane number is used as the fuel. In this spark-ignition internal combustion engine, if a combustible air-fuel mixture with an appropriate air-fuel ratio exists near the ignition means such as a spark plug, good combustion can be achieved by spark discharge regardless of the air-fuel mixture condition in other parts. Therefore, it is important whether or not a combustible air-fuel mixture with an appropriate air-fuel ratio exists in the vicinity of the ignition means.

By the way, in the above-mentioned internal combustion engine, at low load times when the amount of injected fuel is small and it is difficult to generate an air-fuel mixture, the air-fuel mixture becomes very dilute and misfires are likely to occur because the flame does not propagate even by spark discharge.

One idea here is to reduce the amount of intake air by throttling the intake air at low loads.This can improve fuel ignitability, but the problem is that the pumping loss of the engine due to the throttling increases, resulting in poor fuel efficiency, etc. There is. This problem is ultimately based on the fact that when the load is low, a combustible air-fuel mixture with an appropriate air-fuel ratio cannot be secured near the ignition means.

Therefore, as shown in FIG. 3, fuel is injected directly from the fuel injection nozzle a toward the ignition means to form a rich mixture of atomized or vaporized fuel near the ignition means. is possible.

However, more of the air-fuel mixture C exists in the bottom e of the combustion chamber below the ignition means than in the vicinity of the ignition means provided at the top of the combustion chamber d, and appropriate combustion may not be achieved sufficiently.

Here, as shown in FIGS. 4 and 5, the present applicant forms a gathering space j in which the ignited fuel i is gathered in the combustion chamber f by a step formed on the inner wall g of the combustion chamber ``, and An ``internal combustion engine'' in which an ignition means k is provided in this gathering space j, a rich mixture ρ is distributed within the narrow gathering space j, and this mixture ρ is ignited by the ignition means. 61
-52546) was proposed. According to the present proposal, the air-fuel mixture ρ can be densely distributed in the vicinity of the ignition means from low-load times with a small amount of injected fuel to high-load times to reliably ignite and burn the mixture.

[Problems to be Solved by the Invention] By the way, in the above proposal, as shown in FIGS. 4 and 5, the stepped portion is made to stand approximately perpendicularly from the bottom surface m at a different level from the bottom surface m of the combustion chamber f. Because it was raised and raised, the side wall surface p,
q was a wall.

In particular, the side wall surface p facing the rotating swirl n collides with the swirl n and deflects it from the inner wall g side of the combustion chamber f toward the center, and the swirl 0 is the stepped side wall surface p. In some cases, the center of the swirl moved from the center of the combustion chamber f (indicated by r in the figure). Such movement of the swirl center r causes the swirl n to become unevenly distributed within the combustion chamber f, which may change the degree of generation of the air-fuel mixture ρ and prevent a uniform distribution of the air-fuel mixture ρ. Such non-uniform distribution of the air-fuel mixture ρ is not so much of a problem at low loads with low swirl and low fuel injection amount, but at high loads with high swirl and high fuel injection amount, it causes problems such as a decrease in air utilization rate. This results in a decrease in output, deterioration in fuel efficiency, etc.

The present invention was devised in view of the above-mentioned problems, and its purpose is to provide a spark ignition internal combustion engine for low-cetane number fuel when a diesel internal combustion engine is configured as a spark-ignition internal combustion engine for low-cetane fuel. To provide an internal combustion engine that can ensure proper combustion over the entire load range even if it is provided with a stepped section.

[Means for Solving the Problems] The present invention provides a wall surface of a combustion chamber in which a swirl projects outward from the wall surface of the combustion chamber, forms a collection space above which collects ignited fuel, and a swirl passageway is provided below. It is constructed by forming protrusions that form.

[Function] To describe the function of the present invention, when forming a gathering space in which ignited fuel is collected in the combustion chamber, a swirl is created that divides the gathering space and at the same time circulates the swirl swirling inside the combustion chamber below the gathering space. By forming a protrusion that can form a passage inward from the wall of the combustion chamber, it is possible to secure a gathering space that increases ignition performance, and to allow the swirl to circulate over a wide range within the combustion chamber through the swirl passage. ing.

[Embodiment] Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2, a direct injection diesel engine is shown. A rectangular combustion chamber 2 is formed in the piston head 1 by recessing it into a rectangular shape. On the other hand, cylinder head 3
A mounting hole 4 is formed in the mounting hole 4 so as to communicate with the combustion chamber side, and a fuel injection nozzle 5 is provided in the mounting hole 4 so as to face the inside of the combustion chamber 2.

The fuel injection nozzle 5 is of a type similar to a Pinto nozzle, with a spherical head 6 at the bottom of the nozzle having multiple main injection nozzles.
The injection lowers are formed radially, and a sub-nozzle port 9 for sub-injection is formed. Then, the injection nozzle 5 injects the sub-spray F1 from the sub-nozzle 9 in a low-load range where the lift of the needle valve is below a predetermined lift, and in medium-high load ranges where the lift of the needle valve is above a predetermined lift. , in addition to the sub-nozzle 9, the sub-nozzle 9
One injection of nF2 is more proactively injected from the one injection lower. In particular, the injection nozzle 5 has its sub-nozzle 9 connected to a wall surface of the combustion chamber upstream in the flow direction of the swirl S from a corner 2a of the combustion chamber 2 where a protrusion 14, which will be described later, is formed.
The combustion chamber 2 is provided eccentrically with respect to the center C of the combustion chamber 2 so as to face the combustion chamber 2 in the vicinity of the combustion chamber 2. Then, the sub-nozzle 9 injects the sub-spray Fl toward the wall surface 2b, and atomizes the sub-spray Fl.
The vaporized fuel is caused to flow into the combustion chamber 2 by the swirl S.

On the other hand, in the case of the 1-injection lower, a position B that divides the circumferential length of the wall surface 2b into approximately convex equal parts is 1, with the sub-spray injection position A on the combustion chamber wall surface 2b as a reference.
They are arranged radially to correspond to the injection position of the injection rRF 2, and are designed to inject the main spray F2 toward the combustion chamber wall surface 2b.

In the combustion chamber 2 configured in this manner and in which the swirl S revolves, there is a wall 2b extending from the combustion chamber 2 at a substantially central portion in the height direction of the wall surface 2b.
A lip shape or ridge that projects inward and forms a collection space above which collects the ignited fuel F1 injected from the sub-nozzle 9, and also forms a swirl passage P for circulating the swirl S below it. A similar protrusion 14 is formed. Specifically, the protrusion 14 directs the sub-spray F1 from the sub-spray port 9.
The corner 2 of the combustion chamber 2 that is downstream of the swirl S in the injection direction of
It is formed protrudingly on the wall surface 2b of a. And this protrusion 14
forms a narrow space in the upper part of the combustion chamber 2 with a shallower depth, and this space is configured as a collection space in which the air-fuel mixture of the sub-injection flFt flowing by the swirl S is collected. It is supposed to be done.

Further, in the gathering space, an ignition means 15 such as a spark plug having a general configuration for igniting the gathered air-fuel mixture is provided. The ignition means 15 is mounted and supported within a mounting hole 16 formed in the cylinder head 3.

In the present invention, when forming the gathering space as described above, a protrusion 14 is formed extending inward from the combustion chamber wall surface 2b, and a swirl passage P is formed below the gathering space. is formed to improve swirl S and improve combustion especially at high loads. That is, as shown in FIGS. 1 and 2, the swirl passage P is partitioned at the top and bottom by the protrusion 14 and the bottom surface 2C of the combustion chamber below the protrusion 14, and at the same time supports the protrusion 14 on the side and connects the combustion chamber. The combustion chamber 2 is partitioned by a side wall 14a forming a wall surface of the combustion chamber 2, and is formed in communication with the inside of the combustion chamber 2, and the collective space is formed in multiple layers via a protrusion 14. - With this configuration, it is possible to secure a swirl path for the swirl S on the wall surface 2b side of the combustion chamber 2 while ensuring a gathering space, and to make the swirl S swirl in a wide range within the combustion chamber 2.

In the illustrated example, the side wall 14 defining the swirl passage P
a is a circular arc that is gentler than the shape of the corner 2a of the rectangular combustion chamber 2, and is formed along the orbit of the swirl S swirling inside the combustion chamber 2, so that the swirl S can be smoothly circulated. .

Note that this side wall 14a may be formed in the same shape as the other corner portions 2a from the viewpoint of swirl control. A protrusion 1 interposed between these gathering spaces and the swirl passage P
4 partitions the gathering space from the swirl passage P,
It prevents the swirl S from excessively influencing the gathering space to diffuse the air-fuel mixture and blowing out the spark of the ignition means 15, and prevents the swirl S swirling in the combustion chamber 2 from flowing outward. It also functions as a regulatory wall.

The operation of the next embodiment will be described.

When the load is low, such as when the engine is idling, the amount of fuel to be injected is small, and therefore the needle valve foot trough is kept small, and the sub-spray F1 is injected only from the sub-nozzle 9. The injected fuel F1, which has been injected, atomized, and vaporized, is mixed and vaporized, is flowed into the combustion chamber 2 by the swirl S, and is collected in the downstream gathering space.

This gathering space is defined above the projection 14 and is a particularly narrow space within the combustion chamber 2, and the gathered air-fuel mixture is distributed in a rich manner. Under such a rich air-fuel mixture distribution, the ignition means 15 discharges a spark at the end of injection of the sub-spray F1, instantly ignites the air-fuel mixture, and achieves rapid combustion through subsequent flame propagation. Therefore, it is possible to secure a dense air-fuel mixture near the ignition means 15 and ignite it reliably when the load is low. Therefore, even when using fuel such as alcohol or gasoline with a low cetane number, misfire can be prevented, and aldehydes, HC, etc. can be prevented.

Excellent combustion can be achieved with suppressed emissions of unburned alcohol, blue-white smoke, etc. Furthermore, there is no bumping loss due to throttling, and good performance can be achieved in terms of fuel efficiency. At this time, the swirl S considerably flows through the swirl passage P below the protrusion 14, and the ignition means 15 can reliably ignite.

On the other hand, when the load is medium or high, the needle valve is lifted significantly, and the main spray F2 is injected from multiple main lowers along with the sub-spray F1, creating a multi-jet that creates a rich air-fuel mixture distribution throughout the combustion chamber 2. It can be achieved.

As a result, combustion can be carried out with sufficient ignitability.

At this time, even if a gathering space is formed, the swirl S can be smoothly circulated through the swirl passage P below it and can be swirled widely in the combustion chamber 2, so that the center of the swirl is moved far from the center of the combustion chamber 2. combustion chamber 2.
It is possible to suppress uneven distribution of the swirl distribution within the combustion chamber 2, to make the swirl S act uniformly within the combustion chamber 2, and to improve the mixing of air and fuel while distributing the air-fuel mixture as uniformly as possible. Therefore, it is possible to prevent a decrease in air utilization efficiency, improve exhaust gas, secure output, and improve fuel efficiency.

Furthermore, in the above configuration, instead of the fuel injection nozzle 5 having the main lower part and the auxiliary nozzle 9 described above, a plurality of nozzles 17 to 20 having the same diameter are arranged in the spherical head and mutually arranged along the circumferential direction of the combustion chamber wall surface 2b. Fuel injection nozzles 21 formed radially at intervals may also be employed. This nozzle 21 has all these nozzles 11 to 11 from low load to high load.
Fuel Fl from 20.

In particular, the injection nozzle 21, like the above-mentioned sub-nozzle 9, is configured to inject a plurality of nozzles 1 and 2.
At least one of the nozzles 1 to 20 is arranged to face the combustion chamber wall surface 2b upstream in the flow direction of the swirl S from the corner 2a of the combustion chamber 2 where the protrusion 14 is formed so as to be close to the combustion chamber wall surface 2b. It is provided eccentrically with respect to the center C of the combustion chamber 2. The nozzle 17 injects a spray F1 toward the wall surface 2b, and the atomized and vaporized fuel is caused to flow into the combustion chamber 2 by a swirl S.

On the other hand, the other nozzles 18 to 20 are located at positions B where the circumferential length of the wall surface 2b is approximately divided into concave equal parts, with reference to the spray injection position A from the one nozzle 17 on the combustion chamber wall surface 2b, similar to the above-described main lower part.
are arranged radially so as to be the injection position of the spray F2. The other configurations are the same as those of the above embodiment, and the same effects are achieved.

In addition, although the above embodiment has been described with reference to the square combustion chamber 2, a case where a protrusion is formed in a round combustion chamber (not shown) formed by recessing the top of the piston head into a round shape. Even in this case, the same effect as in the above embodiment can be obtained.

[Effects of the Invention] To summarize, the present invention exhibits the following excellent effects.

By forming protrusions on the wall surface of the combustion chamber where the swirl swirls, which protrude into the combustion chamber to form a collection space above which collects ignited fuel, and which forms a swirl passage below, the swirl can be moved into the combustion chamber. It is possible to swirl the entire body smoothly, and it is possible to achieve uniform air-fuel mixture distribution and improve combustion.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing a preferred embodiment of the present invention, FIG. 2 is a plan view of FIG. 1, FIG. 3 is a side sectional view showing a conventional internal combustion engine, and FIG. FIG. 5 is a side sectional view showing an internal combustion engine proposed by someone, and FIG. 5 is a plan view of FIG. 4. In the figure, 2 is a combustion chamber, 2b is a wall thereof, 5.21 is a fuel injection nozzle, 7 is a main nozzle, 9 is a sub-nozzle, 14 is a protrusion, 15
is an ignition means, 17 to 20 are nozzles, D is a gathering space, P is a swirl passage, and S is a swirl. Patent applicant: Patent attorney representing Isuzu Motors Co., Ltd.
Nobuo Kinuya Figure 2

Claims (8)

[Claims] (1) A protrusion is formed on the wall surface of the combustion chamber around which the swirl swirls, protruding into the combustion chamber to form a collection space above which the ignited fuel is collected, and a swirl passage below. Features an internal combustion engine. (2) The internal combustion engine according to claim 1, wherein the swirl passage is formed along the locus of swirl that swirls within the combustion chamber. (3) The internal combustion engine according to claim 1 or 2, wherein an ignition means is provided in the gathering space. (4) The protrusion is formed on the wall of the combustion chamber on the downstream side of the swirl in the direction of fuel injection from the nozzle of the fuel injection nozzle that injects fuel toward the wall of the combustion chamber, projecting inward. An internal combustion engine according to any one of claims 1 to 3. (5) The internal combustion engine according to claim 4, wherein a plurality of the injection ports are provided in the fuel injection nozzle at intervals along the circumferential direction of the wall surface of the combustion chamber. (6) The above-mentioned claim, wherein the protrusion is formed on the wall surface of the combustion chamber on the downstream side of the swirl in the direction of fuel injection from at least one of the plurality of nozzles, so as to protrude inward. Internal combustion engine according to paragraph 5. (7) The nozzle is composed of a main nozzle that injects fuel toward the wall of the combustion chamber in medium and high load ranges, and a sub nozzle that injects fuel toward the wall of the combustion chamber at full load. An internal combustion engine according to claim 4. (8) The internal combustion engine according to claim 7, wherein the protrusion is formed on a wall surface of the combustion chamber on the downstream side of the swirl in the direction of fuel injection from the auxiliary nozzle so as to protrude inward.