JPH0436017A - Fuel collision-diffusion type engine - Google Patents

Abstract

PURPOSE:To restrict the generation of NOx to improve the combustion efficiency by providing a projecting part provided with a colliding face forming connecting holes in its circular passage, and a fuel injection nozzle opening its nozzle hole for injecting liquid fuel to the colliding face, to the accessory chamber. CONSTITUTION:The top face of a projecting part 5 formed on the piston head 13 is formed into a recessed face, and the recessed face forms a recessed colliding face 12 with which liquid fuel injected from a fuel injection nozzle 4 collides. The projecting part 5 is formed so that it can project in the vicinity of the top dead center of a piston 15 from connecting holes 10 formed at the throttled portion 8 into an accessory chamber 2. The jet collided against the colliding face 12 is sprayed as a conical fuel film to the inside of the accessory chamber 2. Furthermore, air flowing into the accessory chamber 2 by squish flow and the conical fuel film are mixed to realize a good mixing and to bring about main combustion of a rich-mixture in the accessory chamber 2. Thus, a good fuel-air mixture is formed to be ignited and burned.

Description

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

[Conventional technology]

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

A direct injection combustion chamber achieves mixing of fuel and air by the injection energy of fuel injected from a fuel injection nozzle and the swirl and squish flow formed within the combustion chamber to form 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 a fuel impingement-diffusion engine using a piston equipped with the oSKA 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 is The piston collides with the surface and diffuses into a disk shape, but the upward stroke of the piston generates a squish flow into the combustion chamber, which creates a thin disk-shaped mixture of fuel and air to improve the combustion state. It makes things better. However, in the fuel impingement diffusion type engine, the combustion chamber burns fuel using a direct injection type rather than an auxiliary chamber type combustion, which poses a problem in suppressing the generation of NOx. .

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. 62-240419 are also disclosed in the above-mentioned publications. Similar to the above, no measures were taken to suppress the occurrence of NO by adopting a pre-chamber type combustion chamber, and the shape of the collision surface was not designed to improve fuel injection in the pre-chamber. It does not take into account.

The purpose of this invention is to solve the above problems,
A sub-chamber is formed in the cylinder head, a protrusion is provided in the piston head that protrudes upward from the top surface, the top surface of the protrusion is formed into a concave collision surface, and liquid fuel is injected onto the collision surface. A fuel injection nozzle is arranged in the sub-chamber, and fuel is injected from the fuel injection nozzle onto the collision surface that enters the sub-chamber, and the injected liquid fuel collides and is uniformly dispersed in a disk shape, thereby forming the disk-shaped fuel film. The purpose of the present invention is to provide a fuel impingement-diffusion type engine that intersects with the first skin flow flowing into the pre-chamber to generate a good air-fuel mixture and ignites and burns it.

[Means to solve the problem]

In order to achieve the above object, the present invention is configured as follows. That is, the present invention provides a subchamber formed in a cylinder head, a communication hole formed in the cylinder head that communicates the subchamber with the main chamber, and a communication hole that protrudes from the top surface of the piston head and connects the communication hole near the top dead center of the piston. a protrusion having a concave collision surface that penetrates into the auxiliary chamber and forms the communication hole in a ring road; and a fuel injection nozzle that opens into the auxiliary chamber a nozzle for injecting liquid fuel onto the collision surface. The present invention relates to a fuel impingement diffusion engine.

Furthermore, in this fuel collision diffusion type engine, the volume of the subchamber is set to 60% of the total volume at the compression end at the piston top dead center.
It is structured as follows.

Further, in this fuel collision diffusion type engine, the protruding portion is formed as short as possible, and during secondary mixing in which the fuel is ejected from the auxiliary chamber to the main chamber, the opening area of the communication hole immediately increases and The flame blows out into the main chamber and spreads within the crank angle where the dead center diameter is small.

[Effect]

The fuel impingement diffusion type engine according to the present invention is constructed as described above and operates as follows. That is, in this fuel collision diffusion type engine, a protrusion having a concave collision surface protruding from the top surface of the piston head is thrust into the subchamber through a communication hole near the top dead center of the piston, and in that state, the protrusion is Since the hole is formed in an annular passageway, the annular passageway essentially forms a communication hole or opening of the subchamber. In this state, liquid fuel is injected from the fuel injection nozzle onto the concave collision surface that has entered the subchamber, so the liquid fuel becomes a conical film along the concave collision surface and diffuses into the subchamber, and the fuel in the conical film The squish flow of air from the main chamber to the auxiliary chamber can produce a good mixture.

In particular, by forming the collision surface in a concave shape, the jet that collides with the collision surface is sprayed into the interior of the subchamber as a conical fuel film. Therefore, the length of the protrusion provided on the piston can be shortened, and the top surface of the piston can be formed to have a preferable shape. In addition, by making the length of the protruding part as short as possible, the protruding part can immediately move downward from the communicating hole after top dead center, so the opening area of the communicating hole can be immediately increased, and the main chamber can be moved from the subchamber to the main chamber. The flame blowout into the chamber can be generated within a small crank angle after top dead center. The balloon at a small crank angle is
It is possible to rapidly reduce the fuel equivalence ratio, lower the combustion temperature, suppress the generation of NOx, and prevent deterioration of engine performance. In addition, it achieves good mixing of the air flowing into the pre-chamber in a squish flow with the disc-shaped fuel, allowing the main combustion to occur in a fuel-rich state in the pre-chamber, resulting in NO
8 can be suppressed.

C Embodiment] Hereinafter, embodiments of the fuel impingement diffusion type engine according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing a fuel impingement diffusion type engine according to the present invention.

As shown in Figure 1, this fuel impingement-diffusion engine is
A cylinder block 9, a cylinder head 3 equipped with an intake boat 6 and an exhaust port 7 fixed to the cylinder frame 9, an auxiliary chamber 2 formed in the cylinder head 3, and the inside of the cylinder 14 formed in the cylinder bronc 9. The main chamber 1 includes a piston 15 that reciprocates, a lower surface portion of the cylinder head 3, a cylinder 14, and a piston head portion 13 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.
is located.

In this fuel collision-diffusion type engine, the piston 15 is made of a metal material such as aluminum, and a protrusion 5 capable of projecting into the auxiliary chamber 2 is formed in the throat portion 13 of the piston 15 .

Further, the auxiliary chamber 2 formed in the cylinder head 3 communicates with the main chamber 1 on the cylinder side through an opening or communication hole 10 formed in a constricted portion 8 formed on the lower surface of the cylinder head. In this fuel collision-diffusion type engine, good pre-chamber type combustion can be achieved by configuring the volume of the pre-chamber 2 to be 60% or less, particularly 40% to 60%, of the total volume at the compression end at the top dead center of the piston. can.

Further, in this fuel collision diffusion type engine, the protruding part 5 of the piston head part 13 is configured to protrude into the subchamber 2 at a position near the top dead center of the piston, and its length is set as long as possible. It is formed short. A fuel injection nozzle 4 having a nozzle 11 opened so as to inject fuel in the direction of the communicating hole 10 is arranged at the center of the subchamber 2 formed in the cylinder head 3. Further, the fuel injection nozzle 4 is composed of a single hole nozzle such as a bottle nozzle, and the piston head 3
The fuel injection nozzle 4 is installed in the auxiliary chamber 2 with the nozzle 11 opened, and is configured such that the fuel injected from the nozzle 11 of the fuel injection nozzle 4 collides with the center of the collision surface 12 of the protrusion 5 in liquid form. ing.

In this fuel collision diffusion type engine, the top surface of the protruding portion 5 formed on the piston head portion 13 is formed as a concave surface,
The concave surface forms a concave collision surface 12 against which the liquid fuel injected from the fuel injection nozzle 4 collides. This protruding portion 5 is configured to be able to enter the subchamber 2 through a communication hole IO formed in the throttle portion 8 near the top dead center of the piston 15.

In particular, by forming the collision surface 12 of the protrusion 5 in a concave shape, the jet that collides with the collision surface 12 is sprayed into the subchamber 2 as a conical fuel film. Therefore, even if the length of the protrusion 5 provided on the piston 15 is made short, fuel can be sufficiently sprayed into the subchamber 2. Furthermore, by forming the protruding portion 5 short, the opening area of the communication hole 10 can be immediately increased in accordance with the downward movement of the piston 15 during the explosion stroke, and the flame blowout from the sub-chamber 2 to the main chamber 1 can be increased. It can occur within a small crank angle after dead center.

Blowing out the flame at a small crank angle can prevent deterioration of engine performance.

In addition, good mixing of the air flowing into the pre-chamber 2 in a conical flow and the conical fuel film can be achieved, and the main combustion can be carried out in the pre-chamber 2 by lynching the fuel, thereby suppressing the generation of NO3.

In this fuel collision diffusion type engine, the cylinder head 3 of the throttle part 8 forming the communication hole 10 that communicates the main chamber 1 and the sub-chamber 2 is made of silicon nitride, which has high heat resistance, although it is not shown. It is preferable to make it from a ceramic material such as (s r 3 N4) or a heat-resistant metal material. Further, although not shown, the piston head portion 13 and the protruding portion 5 can be constructed as an integral structure, and can be made of, for example, ceramics such as silicon nitride (S l 3 Nm ) having high heat resistance.

In this fuel collision-diffusion type engine, the squish flow into the subchamber 2 generated by the upward movement of the piston 15 flows into the subchamber 2 as shown by the arrow. The piston 15 rises and the protrusion 5 enters the auxiliary chamber 2, for example, the piston top dead center ±30
If the fuel enters at the position of
The liquid fuel injected from the concave collision surface 1 of the protrusion 5
2, forming a conical fuel film along the concave surface and diffusing into the subchamber 2. Therefore, the squish flow of air into the subchamber 2 and the conical fuel film intersect at right angles, promoting mixing of air and fuel, and then igniting and burning.

Therefore, this fuel collision diffusion type engine performs pre-chamber type combustion as well as 05KA type combustion in which fuel is diffused into a film by fuel collision, and can constitute an engine that combines the effects of both.

〔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 impingement diffusion type engine has a sub-chamber formed in the cylinder head, a communication hole formed in the cylinder head that communicates the sub-chamber with the cylinder head, and a communication hole protruding from the top surface of the piston head near the top dead center of the piston. a protrusion having a concave collision surface that projects into the sub-chamber through a communication hole and forms the communication hole into an annular passage; and a fuel injection opening in the sub-chamber that injects liquid fuel to the collision surface. Having a nozzle, the annular channel substantially constitutes a communication hole or opening of the antechamber. In this state, liquid fuel is injected from the fuel injection nozzle onto the concave collision surface that has entered the subchamber, so that the liquid fuel becomes a conical film along the concave collision surface and diffuses into the subchamber. However, a good mixture can be produced between the fuel in the conical film and the air in the squish flow from the main chamber to the auxiliary chamber.

In particular, by forming the collision surface in a concave shape, the jet that collides with the collision surface is sprayed into the interior of the subchamber as a conical fuel film. Therefore, the length of the protrusion provided on the piston can be shortened. If the protrusion is formed short, the protrusion immediately separates from the communication hole as the piston descends after the top dead center of the piston.
The opening area of the communication hole increases immediately, and the flame is in a state of being blown out. That is, the top surface of the piston can be formed to have a preferable shape, and the flame can be blown from the auxiliary chamber to the main chamber within a small crank angle after top dead center. Blowing at a small crank angle sharply lowers the fuel equivalence ratio and lowers the combustion temperature, and the secondary combustion in the main chamber
It is possible to immediately clear the OX generation area, suppress the NOX generation, and prevent deterioration of engine performance. Moreover, since the air flowing into the pre-chamber in a skin-like manner and the disc-shaped fuel are mixed well, and the pre-chamber is rich in fuel and the main combustion occurs, the generation of NOx can be suppressed. can.

In addition, in this fuel collision diffusion type engine, the volume of the pre-chamber is configured to be 60% or less of the total volume at the compression end at the top dead center of the piston, so that the most preferable pre-chamber type combustion can be performed, and NOx can be reduced. The occurrence can be suppressed.

Further, in this fuel collision diffusion type engine, the fuel is injected when the collision surface of the protrusion is located in the subchamber, that is, near top dead center, so that the fuel is combusted in the subchamber, The liquid fuel injected onto the impact surface is diffused radially outward along the impact surface, resulting in always good cone-shaped fuel f! forming a membrane, the conical fuel membrane intersecting the squish flow into the subchamber to achieve good mixing of air and fuel;
It is possible to reliably burn the fuel in a rich manner in the pre-chamber, suppress the generation of NOx, and improve combustion efficiency.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a fuel impingement diffusion type engine according to the present invention. °l・----1 main room, 2...-sub-room, 3...-
- Cylinder head, 4 - Fuel injection nozzle, 5 - Protrusion, 8 - Throttle part, 1 (1 -
- Communication hole, 11 - Nozzle, ]] 2 - Concave collision surface 13 - Piston head section, 15 -------
piston. Figure Applicant: Isuso Jidosha Co., Ltd., Patent Attorney: So Naka Onaka

Claims (3)

[Claims] (1) An auxiliary chamber formed in the cylinder head, a communication hole formed in the cylinder head that communicates the auxiliary chamber with the main chamber, and a communication hole that protrudes from the top surface of the piston head and passes through the communication hole near the top dead center of the piston. A fuel impingement device comprising: a protrusion having a concave collision surface that protrudes into the sub-chamber and forms the communication hole into an annular passage; and a fuel injection nozzle that opens a jet hole into the sub-chamber for injecting liquid fuel onto the collision surface. Diffusion engine. (2) The fuel collision-diffusion engine according to claim 1, wherein the volume of the subchamber is 60% or less of the total volume at the compression end at the top dead center of the piston. (3) The protruding portion is formed as short as possible, and during the secondary mixing that is ejected from the auxiliary chamber to the main chamber, the opening area of the communicating hole immediately increases and the opening area is within a small crank angle after top dead center. 2. The fuel impingement diffusion engine according to claim 1, wherein the flame is blown out into the main chamber and diffused.