JP2566710B2 - Combustion chamber of direct injection diesel engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention is, smoke and NO _X
The present invention relates to a combustion chamber of a direct injection diesel engine for simultaneously reducing (nitrogen oxide).

[0002]

2. Description of the Related Art At present, reduction of smoke and NO _x is an important issue in diesel engines, and in order to reduce them, high pressure injection, improvement of combustion system, exhaust gas recirculation (EG
Various proposals such as R) have been made. EGR
Have problems of durability and reliability such as deterioration of fuel consumption and smoke, corrosion of EGR device due to exhaust gas or deterioration of function.

From the viewpoint of the combustion system, in the case of low pressure injection which is widely used at present, after the spray is ignited in the vicinity of the nozzle, it progresses while being wrapped in the whole flame. At this time, the spray is air. At the same time, it burns while energizing the burnt gas generated by itself, so a high temperature part and an oxygen deficient part are formed in the center of the spray, which becomes a cause of smoke generation,
It is said that the burning of burned gas acts as a negative factor. Therefore, in order to reduce smoke, it is necessary to mix fuel and air quickly, and methods such as swirl and squish are used to improve the air utilization rate. Since the mixing speed also increases, there is a contradictory problem that the heat generation rate in the early stage of combustion increases due to the increase in premixed combustion, leading to an increase in NO _X , which makes it difficult to reduce smoke and NO _X simultaneously. ing.

In order to solve the above problems, there is known a system in which a high pressure injection (for example, an injection pressure of 1000 kg / cm ² or more), a small injection hole nozzle, a shallow dish combustion chamber and a low swirl are combined. This will be described with reference to FIG. 3. Reference numeral 1 is a piston, 2 is a piston ring, 3 is a cylinder liner, 4 is a gasket, 5 is a cylinder head, 6 is a fuel injection valve having a nozzle 7, and the top of the piston 1 has combustion. A chamber 9 is formed. When the piston 1 rises and reaches the vicinity of the top dead center, the spray F of the fuel injected from the nozzle 7 ignites at once in the vicinity of the outer peripheral wall 10, and then the flame H expands toward the center of the combustion chamber 9. Since the energy of spray is large, the central part remains as a non-combustible area until the end of injection. That is, the spray progresses while sufficiently entraining air in the non-combustible region side near the center of the combustion chamber 9 until reaching the outer peripheral wall 10, and the outer peripheral wall 10 side collides with the outer peripheral wall 10 while introducing burned gas. Since the smoke is traced along with the above, the smoke is low, and even if the injection timing is greatly delayed, it is ignited. Therefore, in combination with the injection timing delay, it is possible to simultaneously reduce the smoke and the NO _x as compared with the low pressure injection.

[0005]

However, at present, the utilization of air (oxygen) in the combustion chamber is not sufficient, and there is a problem that smoke is generated and discharged, especially when the load is high (fuel injection amount is large). ing. To suppress smoke,
Activates diffusion combustion and maintains strong turbulence until the latter stage of combustion,
Furthermore, it is necessary to keep the turbulent vortices in a fine state.
However, since diffusion combustion occurs in the expansion stroke, the air flow in the cylinder is generally attenuated at that point, and the effect of combustion activation due to turbulence such as intake swirl given during the compression stroke becomes relatively small. Also, in the case of high pressure injection, the turbulence intensity of the flame is high at the beginning of diffusion combustion,
In the latter stage of combustion, it decays and does not differ much from low-pressure injection.

In order to solve this, a combustion disturbance chamber is provided in the cylinder head, a small amount of fuel is injected into this chamber in the latter stage of combustion, and the high pressure combustion gas generated in the chamber is jetted into the combustion chamber. Although a method of directly injecting CO gas into the combustion chamber has been proposed, it has a problem that the device becomes complicated and becomes large in size.

In order to solve this problem, the present inventor has
An experiment was conducted to observe the soot inside the combustion flame. FIG. 4 is a schematic configuration diagram of the experimental device. 11 is a combustion observation engine, 12 is an observation window, 13 is a fuel injection valve, 14 is a fuel supply device, 15 is a combustion chamber, 16 is an extension piston, and 17 is a mirror. , 18 is an argon laser, 19 is a high speed camera, 2
Reference numeral 0 denotes a high-speed camera control device, which irradiates the flame of the combustion chamber 15 in the combustion observation engine 11 with laser light to observe the distribution of soot in the flame from the state of scattered light of the soot. As a result, as shown in FIG. 5 (A), spray F
It was observed that after ignition in the vicinity of the outer peripheral wall 10, the flame H spreads, a high temperature portion and an oxygen deficient portion are formed at the flame tip portion X, and soot is actively generated.

Further, at flame temperature measurement result by the two-color method using image analysis, in the case of high-pressure injection, as shown in FIG. 5 (B), the high temperature of the flame spray collides with the outer peripheral wall 10 one after the other It was observed that a non-uniform temperature distribution was distributed in the vicinity of the tip of the flame pushed out toward the center of the combustion chamber 9 as it burned, and the temperature was lower toward the wall surface 10 [(Fig. Middle, T _H , T _M , and T _L indicate flame temperatures, and T _H > T _M > T _L ): Proc. Page, FIG. 4].

As described above, it has been found that the flame front end causes smoke and NO _x . Therefore, if the high temperature part, the low temperature part, and the oxygen deficient part can be mixed well, the generation of smoke and NO _x can be suppressed.

The present invention is to solve the above-mentioned problems and problems. By agitating the flame, the mixture of the flame and air is activated to reduce the generation of smoke, and the low temperature part and the high temperature part of the flame are reduced. and to provide a combustion chamber of a direct injection type diesel engine of the activation by NO _X mixing can be greatly reduced.

[0011]

For this purpose, the combustion chamber of the direct injection type diesel engine of the present invention is provided with a fuel injection valve 6 provided on a cylinder head 5 and a nozzle 7 of the fuel injection valve 6.
Has a plurality of injection holes, an outer peripheral wall 10 formed on the top of the piston 1, and a hollow portion inside the outer peripheral wall 10.
The outer peripheral wall 10 is positioned so as to be located between the combustion chamber 9 formed as described above and each spray injected from the plurality of injection holes.
And a flame-disrupting members 21 arranged on the inner side of the flame
The disturbing member 21 intersects the plurality of rods 21a and 21b.
And wherein the Rukoto such Te. It should be noted that the numbers added to the above-mentioned configurations are for comparison with the drawings in order to facilitate understanding of the present invention, and the configurations of the present invention are not limited thereby.

[0012]

In the present invention, as shown in FIG. 1, for example, the spray F injected from the injection hole of the nozzle 7 is used.
When the flame H expands left and right and up and down after colliding with the outer peripheral wall 10, the flame H passes through the flame disturbing member 21. At this time, the flame disturbing member 21 promotes mixing of the flame H with the air, and smoke is generated. In addition, the high temperature part of the flame H is disturbed, and the low temperature part and the high temperature part are mixed with each other, whereby the flame temperature is lowered and NO _X can be greatly reduced.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 shows one embodiment of a combustion chamber of a direct injection type diesel engine of the present invention, FIG. 1 (A) is a sectional view, and FIG.
(B) is a partial perspective view.

Reference numeral 1 is a piston, 2 is a piston ring, 3 is a cylinder liner, 4 is a gasket, 5 is a cylinder head, 6 is a fuel injection valve having a nozzle 7, and the nozzle 7 is a nozzle.
Has a plurality of injection holes for injecting fuel. The piston 1 has an outer peripheral wall 10 formed at the top and a combustion chamber 9 formed so as to have a recess inside thereof.
Inside the outer peripheral wall 10, the spray F sprayed from the nozzle 7
The flame disturbing member 21 is arranged between the two. Flame disturbance member 2
1 is made of a material having heat resistance and durability such as stainless steel. A plurality of semicircular rods 21a are arranged in the vertical direction, and a plurality of support rods 21b are arranged on these rods 21a.
Are welded or integrated by intersecting the rods 21a , 21
The tips of b are embedded in holes 22 formed in the outer peripheral wall 10 and the bottom surface of the combustion chamber 9, respectively, and fixed or cast.

The operation of this embodiment having the above structure will be described. The spray F sprayed from the nozzle holes of the nozzle 7 is
After the collision with the outer peripheral wall 10, the flame H passes through the flame disturbing member 21 when expanding in the left-right and up-down directions. At this time, flame H
The flame disturbing member 21 promotes mixing with the air and reduces smoke generation. Further, the high temperature part of the flame H is disturbed, and the low temperature part and the high temperature part are mixed with each other, whereby the flame temperature is lowered and NO _X can be greatly reduced. As mentioned above,
Simultaneous reduction of smoke and NO _X with a simple device can be.

FIG. 2 shows another embodiment of the present invention, which is shown in FIG.
It is a partial sectional view similar to (B). The same components as those in the embodiment of FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In the embodiment of FIG. 2A, the flame disturbing member 2
1 is composed of two planar grid members 21c.
In the embodiment of (B), the flame disturbing member 21 is a trapezoidal grid member 21d, and in the embodiment of FIG. 2C, the flame disturbing member 21 is a cross-shaped member 21e. This
Each of these flame disturbance members 21 is similar to the embodiment of FIG.
Multiple rods are crossed and integrated.

[Brief description of drawings]

1 shows an embodiment of a combustion chamber of a direct injection type diesel engine of the present invention, FIG. 1 (A) is a sectional view, and FIG. 1 (B) is a partial perspective view.

FIG. 2 is a partial perspective view showing another embodiment of the present invention.

FIG. 3 shows an example of a conventional direct injection diesel engine,
FIG. A is a sectional view and FIG. B is a plan view.

FIG. 4 is a schematic configuration diagram of an experimental apparatus according to the present invention .

FIG. 5 shows a spray state for explaining the problems of the present invention.
It is a plan view.

[Explanation of symbols]

1 ... piston, 5 ... cylinder head, 6 ... fuel injection valve,
7 ... Nozzle 9 ... Combustion chamber, 10 ... Outer peripheral wall, 21 ... Flame disturbance member , 21
a, 21b ... rod

Claims (1)

(57) [Claims] 1. A fuel injection valve provided in a cylinder head, and a plurality of injection holes formed in a nozzle of the fuel injection valve,
An outer peripheral wall formed on the top of the piston, a combustion chamber formed to have a recess inside the outer peripheral wall, and so as to be located between the sprays injected from the plurality of injection holes, A flame disturbance member disposed inside the outer peripheral wall ,
Flame disrupting member combustion chamber of a direct injection diesel engine, characterized in Rukoto such by intersecting a plurality of rods.