JPH0419355A - Fuel injection nozzle and fuel injection-flow collision diffusion type engine - Google Patents

Abstract

PURPOSE:To increase the air utilization efficiency and shorten the combustion time period for engine by constructing a single-hole/pin type fuel injection nozzle such that a plurality of notched portions intended for decreasing the flow resistance are provided in the wall portion of the injection port or pin so as to form a plurality of enlarged flow-passage portions in the wall of a flow passage constituted by the annular gap. CONSTITUTION:In an arrangement wherein a collision portion 2 is projectively provided in a cavity 1 formed with respect to a top portion of the piston and wherein, at the time of injection of fuel from an injection nozzle 3, groups of fuel diffused from the collision portion 2 at a speed of injection are sequentially developed within a combustion chamber by squish, thereby to cause the burning reaction to rapidly proceed owing to a synergetic effect of the injection speed and squish, the single-hole/pin type fuel infection nozzle 3 having an annular gap constituted by a cylindrical injection hole 6 and a cylindrical columnar pin portion 4 is formed, at its cylindrical columnar pin portion 4, with four notched portions 5. Thereby, the flow of the injected fuel is divided into three or more flow portions thereof. Thus, when fuel collides against the collision surface 2, owing to the flow energies of the adjoining flow portions and the reactions which take place thereby, the groups of fuel are diffused and developed outwardly from the collision portion 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a collision diffusion combustion technique between a fuel injection nozzle and a fuel jet of an internal combustion engine.

[Conventional technology]

Conventional direct injection compression ignition engines mainly use multi-hole injection valves and have a toroidal combustion chamber above the piston. A fuel injection nozzle is installed in the cylinder head before the top dead center of the piston when the compression action has progressed, and the tip of the nozzle is exposed inside the combustion chamber. Multiple lines of fuel spray are supplied radially into the combustion chamber. The nozzle uses a hole-type automatic valve with multiple fuel injection holes, and the system uses a plunger pump to supply pressurized fuel. In addition, a unit injector type in which a pump and a nozzle are integrated is also used. Three important conditions for fuel injection (fuel atomization, diffusivity, and inertia) are conventionally known, and in order to achieve this objective, relatively high pump pressure is required, and swirl Application of flow has become essential.

In conventional compression ignition combustion systems that use multi-hole nozzles such as Kono, in order to shorten the combustion period, it is necessary to shorten the fuel supply period, which is a prerequisite.
For this purpose, high injection pressure is considered effective. Also, with high injection pressure, the fuel becomes atomized, and although there is a contradiction in terms of its correlation with inertia, it is easy to diffuse, and by promoting atomization, the goal of shortening the ignition delay phenomenon can be achieved. It was expected that it would last.

Based on this concept, increasing the pressure of current injection systems to even higher levels has long been considered an effective means of improving combustion, that is, increasing thermal efficiency and controlling particulates and NOx, and much research and development has been conducted on this topic. It is being done. However, although research and development based on the above concept has continued for over 50 years, there are still problems with this combustion method (diesel combustion), and it is difficult to maintain high thermal efficiency and solve environmental conservation issues such as reducing Hog% particulates. The unavoidable fact is that there is a problem with the fundamentals of combustion in these conventional methods.

The basic problem with conventional combustion systems using multi-nozzle hole nozzles is that although the fuel injection system allows for atomization of fuel, the injection direction is restricted by the number and shape of the nozzle holes. . That is, the atomized fuel group in the early stage of injection rapidly mixes with the air in the area in front of the nozzle hole and combustion is promoted, but oxygen in the reaction area is consumed by this initial combustion. Therefore, the subsequent fuel group is ejected into a high-temperature oxygen-deficient atmosphere, and in this process, the subsequent fuel becomes an oxygen-deficient steamed state, causing a carbonization phenomenon of the fuel. but,
If the carbonized fuel in this process also encounters oxygen again in a high-temperature atmosphere, the reaction progresses and the carbonization phenomenon decreases, but the carbonized fuel composition, which was unable to meet oxygen until the end due to its natural ability, becomes soot. They will be emitted as air pollutants in the form of particulates. As a countermeasure to this, it is an effective means to increase the chance of bonding with the air, and for this purpose, the flow (swirl, squish) in the air is effective.
A means to provide this is essential in conventional combustion methods.

In this way, in the combustion method of conventional direct injection compression ignition engines,
No matter how much you increase the injection pressure and promote atomization of the fuel, it is impossible to obtain a fundamental change in the mixing form of the spray flow from the fixed nozzle and the air, so carbonization occurs due to lack of oxygen in the following fuel group. cannot be fundamentally improved. For this reason, exhaust gas cleaning for current direct injection compression ignition engines requires a catalyst device,
It is necessary to rely on post-processing using trap devices, etc., and the current combustion method maintains high thermal efficiency, conserving resources and reducing CO2 emissions.
01, reduce emissions of NOX% particulates, etc.
It is considered difficult to achieve the objectives of environmental conservation, such as preventing air pollution and global greenhouse effect.

Another direct injection method using a single-hole nozzle is the leg type, K
Although the LOO method and the like have been announced, both methods currently do not exceed the overall performance of the current combustion method using a multi-hole nozzle, and it is difficult to expect any effects from practical use.

As mentioned above, conventional internal combustion engine combustion technologies often require the physical matching conditions of fuel and air that govern the combustion reaction to be within the scope of existing concepts and technologies, and these basics (combination of multi-hole nozzle and swirl) The problem cannot be solved unless we review the situation and create new physical conditions.

[Problem to be solved by the invention]

The present invention solves the drawbacks of the conventional direct injection compression ignition system as described above, and aims to improve the fuel injection conditions governing the combustion reaction.
The aim is to improve the combustion reaction by fundamentally reviewing physical conditions such as air mixing conditions and their matching, and creating new physical conditions.

In addition, by utilizing the impact diffusion effect of fuel jets and squish flow, without using ultra-high pressure, and without requiring swirl air flow, the effects of fuel diffusion, permeation, atomization mixing, etc. This makes it possible to shorten the combustion period. Therefore, we present a new technology that improves specific output within the pressure range of conventionally used injection pumps without increasing the pressure of the injection system to ultra-high pressure, making it possible to improve thermal efficiency and reduce harmful exhaust gas components. In particular, by using fuel jet collision and diffusion technology centered on injection nozzles, various problems that were previously considered difficult to improve can be solved without increasing costs.

In addition, in the collision diffusion method of fuel jets, promoting atomization and atomization of fuel reduces inertia, resulting in a rich fuel region near the collision point and a lack of air in the central region of the combustion chamber. On the other hand, if we use a liquid jet flow that emphasizes diffusion and stability, the diffused fuel particles will become coarser, and more particles will stick to the peripheral wall of the combustion chamber, resulting in more evaporated air-fuel mixture near the wall. This causes problems with the growth of the diffusion flame, air utilization rate, etc.

As described above, in the collision diffusion method, it can be said that the fuel diffusion distribution state due to the collision effect influences the combustion reaction. Therefore, the composition of the fuel jet before the collision is a factor that greatly affects the collision diffusion distribution state, and the nozzle temperature, collision part temperature, matching conditions with squish, etc. are issues that greatly affect the combustion reaction.

[Means to solve the problem]

The present invention uses a uniform conical shape, which is a combination of cylinders and cylinders like conventional nozzle nozzle holes, as a means of configuring the conditions such as inertia, diffusivity, and atomization required in the distributed fuel group in the collision diffusion method. This method negates the structure of the spray form and constructs a fuel injection flow and a collision-diffusion distribution form that is different from the conventional one.

In the present invention, the jet is divided into three or more jet axes by changing the nozzle nozzle shape, and when a collision occurs on the collision surface, the collision part is divided by the flow energy of each adjacent jet axle and the resulting reaction. The purpose is to spread and deploy the fuel group toward the outer region as a starting point. By constructing multiple fuel density variation regions in the diffused fuel group and by creating a mixture group containing coarse and fine particles, we aim to increase the number of points in the initial reaction area over a wide area and ensure consistency. This aims to improve air utilization efficiency and shorten the combustion period.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows the cavity (j), the Kf protrusion (2), and the injection nozzle (3) of this compression ignition engine using the fuel jet impingement diffusion method.
The arrow (A) indicates the direction of air flow due to the squish action near the top dead center. The spread range of the fuel group due to collision diffusion spreads over the entire cavity opening, but due to the strong squish flow, the diffused fuel group supplied before top dead center is spread into the cavity as shown by the dotted arrow.

Near top dead center, both the compression pressure and the ambient temperature have sufficiently reached the conditions for fuel ignition, and the fuel supplied from the nozzle is activated from the optimal mixture region for ignition in the mixture group, resulting in rapid diffusion combustion. to move to. The atomization conditions from the nozzle holes are suppressed, and the atomized diffused fuel starting from the collision part undergoes a combustion reaction from multiple annular regions centered around the collision part. In this case, the reaction flame zone @) is sequentially diffused into the cavity by squish rate control, so that the subsequent fuel group is also sequentially mixed with air by squish flow to form a diffusion flame without running out of air during the initial combustion reaction.

That is, starting from the collision part, the diffused fuel group due to injection rate control is sequentially expanded into the combustion chamber by the squish flow. The combustion reaction progresses rapidly due to the combined action of the injection rate-limiting and squish rate-limiting, and as a result, the objectives of improving air utilization and shortening the combustion period are achieved.

Figure 3 shows a conventional pin-type nozzle whose pin part has been modified to provide four notches (5) in the conventional cylindrical pin part (4). Figure 2 shows the impact of the jet flow caused by this nozzle in the combustion chamber. This is a perspective view of the diffusion state.

The divided flows in the four directions also move due to the rotation of the pin.
There is little variation in the air-fuel mixture density in each divided region in the circumferential direction, and there is stability, and there is a region with high fuel density in the center of each divided region.

At the beginning of the diffusion process, initial flame kernels are generated at multiple points in the optimal air-fuel mixture region around the collision surface, causing a chain reaction to grow as a diffusion flame, and the reaction develops in the combustion chamber one after another.

Another important role in the fuel jet impingement action is to rapidly reduce the speed of the fuel particles dispersing due to the impingement action at the same time as the fuel spreads.

By attenuating the fuel particle velocity, the heat transfer loss between the fuel particles and the surrounding air is reduced, and the time-series and multi-point reaction from a wide range of atomized air-fuel mixture regions due to collision diffusion is reduced. is induced, and combustion progresses more rapidly from these points.

In the present invention, a single-hole pin-type nozzle is used so that the fuel jet retains sufficient flow energy until it reaches the collision surface, and is advantageous in forming sufficient inertia and diffusion distribution state in the collision-diffusion effect. In the case of a hole nozzle, by changing the shape of the nozzle nozzle, and by configuring the nozzle holes in a parallel configuration with multiple holes, multiple jet axes are formed in the jet, and these collide as a cohesive jet. This is to suppress the fuel atomization effect while the jet reaches the collision surface, and to maintain the inertia of the fuel particle group and atomize it by the diffusion effect after the jet reaches the collision surface. It is characterized by combustion in which the first condition is the creation of a combustion reaction atmosphere that promotes the combination of air and fuel particles in a time-series manner.

[For production]

Characteristics of the injection nozzle (3), which is the main character of this combustion method,
As shown in Figure 5 (7), in a single hole pin type nozzle, the nozzle hole (6
) or a notch (5) is provided in the pin part (4), and by reducing the flow path resistance, a plurality of equiangular jet axes with high fuel density are formed in the jet.

In addition, in the hole type nozzle (7), as shown in Figure 4, the nozzle holes (8) are placed close to each other at equiangular positions (C) (D) (to).
) and I) are constructed in parallel as multiple jets, and in addition to the collision reaction caused by mutual axial flow energy close to each other at the collision surface due to the configuration of multiple jet shafts formed separately, there is also a collision reaction caused by heat exchange at the time of collision. The synergistic effect of the vaporization and expansion effect of the fuel is intended to increase the penetration of the fuel in the direction of the outer circumferential area (arrow) and to strengthen the diffusion effect. In addition, non-uniformity in particle size is created in the group of diffused fuel particles, consistency is ensured by the group of coarse particles (9), and ignition promotion effect is improved by the group of fine particles and intermediate particles.

In addition, by making the fuel group a mixed group of coarse and fine fuel particles, a multi-point ignition condition with microscopic time differences is created in the combustion reaction atmosphere, and small turbulence is created by the notch in the squish flow. The synergistic effect of these actions increases the combustion rate (period) of the entire air-fuel mixture region, and also improves the air utilization rate.

〔effect〕

The present invention saves energy resources through high thermal efficiency, and at the same time greatly improves the drawbacks of direct injection compression ignition engines, which are advantageous in emitting Cow, which is the main cause of the global greenhouse effect, and eliminates particulate matter, which is a harmful exhaust gas. ), NOx
Regarding the fuel jet impingement-diffusion combustion method, which greatly reduces energy consumption and maintains high thermal efficiency, we presented the technical conditions to achieve the physical matching conditions between the fuel injection conditions and the air, which are the main factors.

This method does not require ultra-high pressure in the injection system, which is advantageous for production in terms of cost.In addition, the improvement in air supply efficiency by not requiring swirl directly improves the specific output of the engine. be.

Furthermore, thermal efficiency is improved by shortening the combustion period, and even when NOx reduction technologies such as injection retardation and IC01 are used in combination, the combustion characteristic has a combustion characteristic with little reduction in thermal efficiency.

In addition, it has various fuel characteristics that are effective when using low-quality fuels other than light oil, and has significant effects such as shortening ignition delay and reducing noise by increasing the temperature of the collision part.

[Brief explanation of drawings]

The drawings are for explaining the structure and operation of the present invention.
is a cross-sectional view showing the relationship between the piston combustion chamber, the fuel collision part, and the injection nozzle in a compression ignition system. It shows the trends of the diffusion group under the influence. FIG. 2 is an explanatory diagram, seen transparently from above, of the divided density composition of the collision-diffusion fuel group by a pin-type nozzle (4-hole nozzle) or a 4-hole nozzle in the combustion chamber of FIG. FIG. 3 is an explanatory diagram of a case in which a small equiangular notch is formed in the pin part of a pin-type single-hole nozzle, and FIG. Hole type nozzle, C...5 holes, D...4 holes, K-...5
Hole? ...5 holes? ...This shows the case of 6 holes. In the figure, A shows the squish flow direction near the compression top dead center, and B shows the flow direction of the fuel mixture group under the influence of the squish flow. ℃・・・Fuel jet from the nozzle. diagram diagram

Claims (4)

[Claims] (1) In a single-hole pin type fuel injection nozzle in which an annular gap is formed by a cylindrical nozzle hole and a cylindrical pin part, a plurality of notches are provided in the wall of the nozzle hole or pin to reduce flow resistance. An injection nozzle for an internal combustion engine, characterized in that a plurality of flow passage enlarged portions are formed equiangularly in a flow passage cross section formed by an annular gap. (2) A hole-type fuel injection nozzle for a fuel jet impingement-diffusion combustion internal combustion engine, characterized in that three or more injection holes are positioned close to each other at equal angles and the flow paths are configured in parallel. (3) In the compression ignition combustion method, which creates a disc-shaped fuel diffusion distribution by the collision action of fuel jets, regions of high fuel density are created equiangularly in the disc-shaped diffusion distribution pattern from 3 to 6.
This compression ignition combustion method is characterized by controlling the combustion reaction in time series by forming the fuel mixture in the range of 1 to 1 and making the fuel density and fuel atomization state in the mixture non-uniform. (4) In a combustion method in which a mixture or a diffusion flame is created by the collision-diffusion effect of fuel, by changing the density distribution in the fuel jet, a fuel density variation area is created in the collision-diffusion fuel group, and the diffusion fuel group is further A fuel jet impingement-diffusion internal combustion engine that is characterized by intentionally making the mass of particles in the fuel jet non-uniform to widen the initial ignition conditions and make them multi-point, thereby shortening the combustion period.