JPH0436016A - Fuel collision-diffusion type engine - Google Patents

Abstract

PURPOSE:To restrict the generation of NOx by providing a fuel injection nozzle arranged at a projecting part in which a circular passage connecting a main chamber to a combustion chamber is formed, and opening its nozzle hole into the combustion chamber opposite to a projection body. CONSTITUTION:A projection body 5 is formed on the nearly middle bottom of a combustion chamber 2. A colliding face 12 formed on the projection body 5 constitutes a face against which liquid fuel collides. A fuel injection nozzle 4 is mounted to a projecting part 8, and the fuel injection nozzle 4 opens its nozzle hole 11 into the combustion chamber, opposite to the colliding face 12 of the projecting body 5 provided in the combustion chamber 2. An opening part 10 is formed into a circular passage 13 whose connecting area is throttled, and the combustion chamber 2 substantially functions as an accessory chamber. Thus, combustion capable of restricting the generation can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fuel impingement diffusion type engine in which fuel injected from a fuel injection nozzle directly impinges on a protrusion provided within a combustion chamber.

[Conventional technology]

Conventionally, engine combustion chambers are typically of the direct injection type and the pre-chamber type.

The direct injection combustion chamber achieves mixing of fuel and air by the injection energy of the fuel injected from the fuel injection nozzle and the swirl and squish flow formed within the combustion chamber, forming a flammable mixture. However, the direct injection combustion chamber has the problem of reduced intake efficiency due to swirl generation, and in order to atomize the fuel spray and increase penetration power, the fuel injection nozzle must be pressurized to a high pressure. This has the problem that it must be configured to have a high injection rate, making the structure complicated.

Further, the pre-chamber type combustion chamber achieves mixing of fuel oil droplets and air by a high swirl formed in the pre-chamber to form a flammable air-fuel mixture. The pre-chamber type combustion chamber has the problem that a high swirl is formed in the pre-chamber, and the total heat transfer area of the main chamber and the sub-chamber increases, increasing heat loss. There is a problem in that the aperture loss due to the communication hole that communicates with the chamber increases.

Therefore, in order to solve the above problems, we developed a direct injection collision diffusion stratified air supply system that uses collision jets of fuel.
An engine with a 03KA type combustion chamber is disclosed.

This 03KA type engine has a recess formed in the piston, that is, a collision part protruding from the center of the bottom of the cavity, a concave combustion chamber is formed around the collision part, and liquid fuel injected from a fuel injection nozzle is transferred to the collision part. The collision effect of the fuel jet on the collision part causes diffusion and atomization of the fuel starting from the collision surface, thereby achieving good mixing of the fuel and air. In an engine with a combustion chamber as described above, the fuel injected from the single-hole nozzle of the fuel injection nozzle collides with the flat collision surface of the collision part of the piston head and is dispersed in a disk shape, which is then caused by the rise of the piston. The squish flow forces the fuel down into the cavity, and the fuel and air are mixed to form an air-fuel mixture.

Further, Japanese Patent Application Laid-Open No. 195408/1983 discloses a diesel engine that uses collision reflection diffusion of fuel jets. In this diesel engine, the first period is the period during which the fuel jet starts from the injection hole of the fuel injection nozzle and reaches the jet impingement surface in the cavity, and the period during which the fuel portion deflected by the collision surface reaches the cavity wall surface is the first period. The second stage is the second stage, and the third stage is the period during which the fuel that reaches the wall evaporates and vaporizes, and the combustion reaction of each period occurs.The fuel jet from the nozzle collides with the collision surface in the cavity, causing a collision. The collision surface is configured to have a polygonal shape so that fuel can be diffused and distributed in any direction by reaction.

Furthermore, Japanese Patent Application Laid-Open No. 62-240419 discloses a direct injection diesel engine. In the direct injection type diesel engine, fuel injection from a fuel injection valve is completed before compression ignition is performed so that liquid fuel adheres to the inner peripheral wall surface of a cavity formed on the top surface of the piston. The fuel impingement wall on the inner circumferential wall of the cavity includes a flat circular central portion, a substantially conical projection formed at the center of the circular central portion, and an inclined surface extending radially from the circular central portion.

[Problem to be solved by the invention]

By the way, in an engine using a piston equipped with the above-mentioned 05KA type combustion chamber, the collision surface on which the fuel injected from the single-hole nozzle collides is the flat collision surface of the piston head, and the fuel collides with the flat collision surface of the piston head. However, due to the upward stroke of the piston, a squish flow is generated into the combustion chamber, and this squish flow creates a thin film disc-shaped mixture of fuel and air to improve combustion conditions. It is. However, at part load of the engine, N
Although the number of Oll orders has been suppressed to some extent, when the engine is under high load, the temperature inside the combustion chamber becomes high, and since fuel is combusted by direct injection, there is a problem in that the generation of NO9 increases.

Further, the diesel engine using collision reflection diffusion of fuel jets disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 62-195408 and the direct injection diesel engine disclosed in the Japanese Patent Application Laid-Open No. 62-240429 are also disclosed in the above-mentioned publications. Similarly, when injecting fuel, the communication hole is narrowed to ensure good mixing of the squish flow into the combustion chamber formed in the piston and the fuel, and the main combustion is not performed in the combustion chamber, but to reduce the generation of N080. No countermeasures have been taken to suppress this, and furthermore, no consideration is given to the shape of the collision surface to improve fuel injection in the combustion chamber.

The purpose of this invention is to solve the above problems,
forming a protrusion on the cylinder head, disposing a fuel injection nozzle in the center of the protrusion, forming a combustion chamber formed on the piston head and a communication hole communicating the combustion chamber and the main chamber;
A protrusion having a collision surface is disposed in the combustion chamber, and fuel is injected onto the collision surface from a fuel injection nozzle provided in the cylinder head, and the injected liquid fuel is made to collide with the collision surface to produce disk-shaped fuel. The cylinder head is diffused uniformly into the film, and as the piston rises, the protruding part of the cylinder head is thrust into the communication hole to form the communication hole into an annular passage, and the opening area of the annular passage is narrowed down to make the combustion chamber equivalent to the auxiliary chamber. The flow direction of the air flowing in in a squish flow through the annular passage intersects the fuel injection direction of the fuel which is diffused and injected in a disc shape to promote mixing of the fuel and air. A fuel impingement-diffusion engine that performs main combustion in a fuel-rich state in the combustion chamber serving as an auxiliary chamber to reduce the generation of NOx, and performs good combustion to prevent the discharge of unburned fuel or intermediate products. The goal is to provide the following.

Means for Solving CtliM] In order to achieve the above object, the present invention is configured as follows. That is, the present invention includes a combustion chamber formed in a piston head, a protrusion provided at the substantially center bottom of the combustion chamber and provided with an impact surface for injected fuel, and a protrusion protruding from the lower surface of the cylinder head and protruding into the opening of the combustion chamber. The present invention relates to a fuel impingement diffusion engine having a protrusion forming an annular passage connecting a main chamber and the combustion chamber, and a fuel injection nozzle disposed in the protrusion and having a nozzle opening facing the protrusion. .

Further, in this fuel collision diffusion type engine, the annular passage is narrowed by the protrusion and a peripheral wall of the opening in a state in which the protrusion enters the entrance part of the combustion chamber at the top dead center of the piston, A squish flow flowing into the combustion chamber from the main chamber through the annular passage collides with the impact surface of the protrusion from the fuel injection nozzle and intersects with the fuel film that spreads.

Further, in this fuel collision diffusion type engine, during secondary mixing when the fuel is ejected from the combustion chamber to the main chamber, the opening area of the annular passage increases, and the ejected gas diffuses into the main chamber.

In this fuel collision diffusion type engine, the volume of the combustion chamber is set to 40% of the total compression end volume at the piston top dead center.
% to 60%.

[Effect]

The fuel impingement diffusion type engine according to the present invention is constructed as described above and operates as follows. That is, this fuel impingement diffusion type engine forms a combustion chamber in the piston head,
A protrusion protruding from the lower surface of the cylinder head enters the opening of the combustion chamber to form a communication hole connecting the main chamber and the combustion chamber into an annular passage, and is formed in a protrusion provided at approximately the center bottom of the combustion chamber. Since the injected fuel from the fuel injection nozzle formed in the cylinder head impinges on the collision surface, the annular passage narrows the maximum diameter of the communication hole or opening of the combustion chamber to a smaller size, and the combustion chamber is substantially It will perform the combustion function as an auxiliary chamber. In this state, liquid fuel is injected from the fuel injection nozzle to the collision surface, so the liquid fuel becomes a disc-shaped film along the collision surface and diffuses into the combustion chamber, and the fuel in the disc-shaped film and the main chamber flow into the combustion chamber. The squish flow of air can produce a good mixture. In particular, it is possible to achieve good mixing of the air flowing into the combustion chamber in a squish flow and the disc-shaped fuel, and to perform fuel-rich main combustion in the combustion chamber, thereby suppressing the generation of NOl.

That is, the fuel injected from the fuel injection nozzle collides with the collision surface in liquid form and spreads radially outward along the collision surface to form a disc-shaped fuel film, but the fuel is not guided by the protrusion. The squish flow can be caused to intersect with the disk-shaped fuel film, thereby achieving good mixing of fuel and air and improving combustion efficiency.

〔Example〕

Embodiments of the fuel collision-diffusion engine according to the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram showing the end of the compression stroke of an embodiment of the fuel impingement diffusion engine according to the present invention, FIG. 2 is an enlarged view of the portion A in FIG. 1, and FIG. It is an explanatory view showing the initial stage after top dead center of a diffusion type engine.

As shown in Figure 1, this fuel impingement-diffusion engine is
A cylinder block 9, an intake boat 6 fixed to the cylinder block 9, a cylinder rod 3 having an exhaust port 7, a cylinder liner 14 fitted into a hole in the cylinder block 9, and a cylinder liner 14 that moves reciprocally within the cylinder liner 14. Piston 15, cylinder liner 14, cylinder head 3
It has a main chamber 1 formed by the lower surface of the piston 15 and the top surface of the piston 15. An intake valve 16 is arranged in the intake boat 6, and an exhaust valve 17 is arranged in the exhaust port 7. The piston 15 is made of a metal material such as aluminum, and a cavity or combustion chamber 2 is formed in the piston head portion of the piston 15. In particular, regarding the combustion chamber 2 formed in the piston head, a protrusion 5 extending upward is formed at the center bottom of the piston head. This protrusion 5
For example, zirconia (Z r Ox
) can be attached to thin plates made from ceramics such as The upper part of the protrusion 5 extends upward from the bottom surface of the cavity and is located below the opening 100 surface of the combustion chamber 2, that is, the top surface of the piston head.

The upper part of this protrusion 5 is formed as a disk portion 5P, and the top surface of the disk portion 5P is formed as a flat collision surface 12. This collision surface 12 constitutes a surface on which liquid fuel collides.

Further, the cylinder head 3 is formed with a protrusion 8 that extends downward and faces the combustion chamber 2 formed in the piston head. The protrusion 8 is configured to protrude into the combustion chamber 2 from the opening 10 near the top dead center of the piston. A fuel injection nozzle 4 is attached to the center of the protrusion 8 , and the fuel injection nozzle 4 has a nozzle 11 opening facing the collision surface 12 of the protrusion 5 provided in the combustion chamber 2 . The fuel injection nozzle 4 is composed of a single-hole nozzle such as a bottle nozzle, and is configured such that the fuel injected from the nozzle 11 of the nozzle collides with the center of the collision surface 12 in liquid form.

Further, the volume of the combustion chamber 2 is configured to be 60% or less, particularly 40% to 60%, of the total compression end volume at the top dead center of the piston. Moreover, since the protrusion 8 provided on the cylinder head 3 near the top dead center enters the opening 10, the opening 10
0 becomes an annular passage 13 and the communication area is narrowed down.

Therefore, the combustion chamber 2 substantially functions as an auxiliary chamber, and the N08
It is possible to perform combustion that suppresses the generation of

Therefore, the protruding part 8 provided on the cylinder head 3 protrudes downward corresponding to the peripheral wall of the entrance part 10 which is formed in the piston head and communicates with the combustion chamber 2. 8 and the peripheral wall or wall surface 19 of the opening 10
and form an annular passage 13. Therefore, the squish flow generated by the rising of the piston and flowing into the combustion chamber 2 from the main chamber 1 is guided by the outer peripheral surface 1B of the protrusion 8, and the jet direction is changed as shown by the arrow, and the squish flow flows into the combustion chamber 2 wall surface 19. The flow becomes downward along the line. Therefore, the downward flow of the skin flow is strengthened, and the strengthened skin flow crosses the disc-shaped fuel film injected from the injection port 11 of the fuel injection nozzle 4, promoting mixing of air and fuel.

The fuel collision diffusion type engine according to the present invention is constructed as described above and operates as follows.

In this fuel collision diffusion type engine, the protrusion 8 provided on the cylinder head 3 projects into the opening 10 formed in the piston head, so that the opening IO forms an annular passage 13 with a narrowed cross-sectional area. Therefore, the combustion chamber 2 has the same function as the auxiliary chamber. Therefore, by the rise of the piston 15, the air in the royal room 1 is transferred to the annular passage 13.
The air flows into the combustion chamber 2 as a liquid flow through the combustion chamber 2, but since the opening 10 becomes an annular passage 13 and its cross-sectional area is narrowed, the liquid flow is strengthened.

Further, as shown in No. 111K, the fuel injected at low pressure from the nozzle 11 of the fuel injection nozzle 4 attached to the cylinder head 3 is converted into a rod-shaped liquid fuel near the end of the compression stroke in the combustion chamber 2 facing the nozzle 11. It collides with the impact surface 12 of the protrusion 5, becomes a thin film-like disk, and diffuses outward in the radial direction. At this time, the squish flow strengthened by the rise of the piston 15 is guided by the outer peripheral surface 18 of the protrusion 8 provided on the cylinder head 3 and flows into the combustion chamber 2 through the annular passage 13.

Therefore, it is possible to achieve good mixing by intersecting the squish flow and the disk-shaped thin film fuel in a perpendicular state, and in particular, since the primary combustion in the combustion chamber 2 is performed in a closed space with fuel rich, NOx It is possible to suppress the occurrence of , ensure good combustion conditions, and improve combustion efficiency.

Then, as shown in FIG. 3, after the top dead center, the piston 15
, the passage cross-sectional area of the opening 0 suddenly increases, the flame flows out from the combustion chamber 2 to the second chamber 1, the fuel equivalence ratio rapidly decreases, and the combustion temperature suddenly increases. decreases to Therefore, a combustion state in the NOx generation area can be avoided, and the generation of negative layer NOx can be suppressed.

Next, another embodiment of the fuel impingement diffusion type engine according to the present invention will be described with reference to FIG. The fuel collision-diffusion engine of this embodiment has the following features compared to the above embodiment:
They have exactly the same configuration and function except that the shape of the main chamber 1 is slightly different. Therefore, in the fuel impingement-diffusion engine of this embodiment, the same parts as those in the fuel impingement-diffusion engine shown in FIG. That is, the main chamber 1 in this embodiment has a structure in which the recess 20 is formed in the top surface of the piston 15 to clearly define the main chamber 1.

〔Effect of the invention〕

The fuel collision diffusion type engine according to the present invention is configured as described above, and has the following effects. That is, this fuel collision diffusion type engine includes a combustion chamber formed in the piston head, a protrusion provided at approximately the center bottom of the combustion chamber and provided with an impact surface for the injected fuel, and an opening of the combustion chamber that protrudes from the lower surface of the cylinder head. The fuel injection nozzle is provided with a protrusion that protrudes into the combustion chamber to form an annular passage connecting the main chamber and the combustion chamber, and a fuel injection nozzle that is disposed in the protrusion and opens a nozzle facing the protrusion. The annular passage reduces the cross-sectional area of the communication hole or opening of the combustion chamber to a smaller extent, so that the combustion chamber essentially functions as a subchamber. When the opening is narrowed, the squish flow flowing from the main chamber into the combustion chamber is strengthened.

On the other hand, when liquid fuel is injected from the fuel injection nozzle to the collision surface, the liquid fuel becomes a disc-shaped film along the collision surface and diffuses into the combustion chamber. Therefore, the fuel in the disc-shaped film and the air in the enhanced squish flow from the main chamber to the combustion chamber can form a good mixture. In particular, by achieving good mixing of the air flowing into the combustion chamber in a squish flow and the disk-like fuel, the combustion chamber is fuel-rich and the main combustion occurs.
o, can be suppressed from occurring.

Next, after the top dead center, the piston begins its downward stroke, and the annular passage changes to an opening with a large area, and the passage cross-sectional area of the opening suddenly increases, and the ejected gas, that is, the flame, is suddenly released from the combustion chamber. The fuel flows out into the chamber and diffuses, causing a sharp drop in fuel equivalence ratio and a sharp drop in combustion temperature. Therefore, even in the secondary combustion, the combustion state in the NOx generation region can be avoided, and the generation of NOx can be further suppressed.

That is, the fuel injected from the fuel injection nozzle collides with the collision surface in liquid form and spreads outward in the radial direction along the collision surface to form a disc-shaped fuel film.
The squish flow guided by the self-projecting portion can intersect the squish flow through the disc-shaped fuel film, thereby achieving good mixing of fuel and air and improving combustion efficiency.

In this fuel collision diffusion type engine, the volume of the combustion chamber is set to 40% of the total compression end volume at the piston top dead center.
% to 60%, the combustion chamber can function as the most preferable auxiliary chamber.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the end of the compression stroke of an embodiment of the fuel collision diffusion type engine according to the present invention, FIG. 2 is an enlarged view of the portion A in FIG. 1, and FIG. 3 is a fuel collision diagram in FIG. 1. FIG. 4 is an explanatory diagram showing the initial stage of the combustion stroke of a diffusion type engine, and FIG. 4 is an explanatory diagram showing another embodiment of the fuel collision diffusion type engine according to the present invention. 1----- Life chamber, 2----- One combustion chamber, Rad, 4
---Fuel injection nozzle, P--1 disk part, 8--1 protruding part, opening part, 11-
・------ Nozzle, 12---- Annular passage, 15---
--Piston, 3.---.--Protrusion to cylinder, 5 10---Impact surface of combustion chamber, 13 20.--Recess.

Claims (4)

[Claims] (1) A combustion chamber formed in the piston head, a protrusion provided approximately at the center bottom of the combustion chamber and provided with an impact surface for the injected fuel, protruding from the lower surface of the cylinder head and located near the top dead center at the opening of the combustion chamber. A fuel impingement diffusion type having a protrusion that protrudes to form an annular passage connecting the main chamber and the combustion chamber, and a fuel injection nozzle that is disposed in the protrusion and opens a nozzle facing the protrusion. engine. (2) The annular passage is narrowed by the protrusion and the peripheral wall of the opening when the protrusion enters the opening of the combustion chamber at the top dead center of the piston, and the annular passage is narrowed by the protrusion and the peripheral wall of the opening. 2. The fuel impingement-diffusion engine according to claim 1, wherein a squish flow flowing into the combustion chamber from the fuel injection nozzle impinges on the impact surface of the protrusion and intersects with a fuel film that spreads. (3) At the time of secondary mixing, which is ejected from the combustion chamber to the main chamber, the area of the opening immediately increases, and within a small crank angle, the flame blows out from the combustion chamber to the main chamber and spreads. The fuel impingement diffusion engine described in . (4) The fuel collision-diffusion engine according to claim 1, wherein the volume of the combustion chamber is 40% to 60% of the total compression end volume at the top dead center of the piston.