JPH051542A - Direct injection type internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce the extent of smoke, particulate and NOx. CONSTITUTION:An inner circumferential wall body 14, partitioning off an inside combustion chamber 13, is formed in the more radial inward than a peripheral side wall 12 of a cavity 11 indented in a piston top part 2. A part of this inner circumferential wall body 14 is notched, forming a notch 21. A first nozzle hole 16 spraying fuel to the peripheral side wall 12 through this notch 21, and a second nozzle hole 17 spraying fuel to the inner circumferential wall body 14 through an opening area smaller than the first nozzle hole 16 both are installed in a fuel injection nozzle 18. The fuel sprayed is simultaneously ignited in and around the peripheral side wall 12 and the inner circumferential wall body 14, and it is subjected to two-stage combustion, while mixing promotion by means of blowing-off of a flame takes place, thus uniform and good combustion is achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct injection type internal combustion engine in which fuel is directly injected into a combustion chamber for combustion.

[0002]

2. Description of the Related Art A direct injection type internal combustion engine is known as an internal combustion engine (diesel engine) in which fuel is directly injected into a combustion chamber for combustion.

As shown in FIGS. 20 and 21, a conventional direct injection type internal combustion engine of this type is provided in a cylinder head 4 and a combustion chamber 3 defined as a cavity which is appropriately recessed in a top portion 2 of a piston 1. A fuel injection nozzle 5 for injecting fuel into the lever combustion chamber 3 is provided. A peripheral side wall 6 of the combustion chamber 3 is provided at the tip of the fuel injection nozzle 5.
Is formed so as to oppose each other, and fuel from a fuel pump (not shown) is injected at a predetermined pressure. Further, the shape of the fuel spray L matches the shape of the combustion chamber 3, so that the fuel is evenly distributed in any direction as much as possible. The injected fuel is appropriately mixed with the air taken into the combustion chamber 3, ignited from the tip side of the spray L (near the peripheral side wall 6), and the combustion proceeds to the center (near the fuel injection nozzle 5). Thus, the desired combustion can be obtained.

In order to mix the spray L and air well to obtain good combustion, various structures have been proposed for producing appropriate turbulence (swirl, squish) in the air in the combustion chamber 3.

[0005]

By the way, recently, in order to completely atomize the fuel and obtain combustion with low smoke and particulates, the injection pressure is made as high as possible. However, if the injection pressure is excessively increased, uniform combustion is not performed, and there is a problem that NO _X is generated due to high temperature combustion or excessive pressure rise.

[0006] The present invention has been made in view of the above circumstances, smoke, at the same time as the reduction of particulates, it was conceived to provide a direct injection internal combustion engine which can reduce the NO _X.

[0007]

SUMMARY OF THE INVENTION According to the present invention, an inner peripheral wall body is formed which defines an inner combustion chamber radially inward of a peripheral side wall of a cavity recessed in the piston top and a part of which is appropriately cut out. A fuel having a combustion chamber, a first injection hole for injecting fuel to the peripheral side wall through a notch in the inner peripheral wall, and a second injection hole having an opening area smaller than that of the first injection hole and facing the inner combustion chamber. And an injection nozzle.

Further, the inner combustion chamber has a projection provided so as to face the second injection hole and a groove formed on an opposite surface of the projection and directed to an appropriate position of the inner peripheral wall body. Is desirable.

[0009]

With the above structure, the fuel is injected from the first injection hole to the peripheral side wall of the combustion chamber, and the spray from the second injection hole is supplied to the inner side combustion chamber. It is ignited at the same time. The gas in the inner combustion chamber is pushed out over the inner peripheral wall, and the unburned components are disturbed with the air to promote mixing, and the two-stage combustion is performed.

Further, since the inner combustion chamber has the projection and the groove, the fuel injected from the second injection hole collides with the projection and is guided to the groove and diffused to a predetermined position of the inner peripheral wall.

[0011]

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

1 and 2 show a first embodiment of a direct injection type internal combustion engine according to the present invention.

This direct injection type internal combustion engine has a combustion having an inner peripheral wall body 14 which is formed radially inward of a peripheral side wall 12 of a cavity 11 recessed in a top portion 2 of a piston 1 to define an inner combustion chamber 13. The chamber 15, the first injection hole 16 for injecting fuel to the peripheral side wall 12, and the second injection hole 1 facing the inner combustion chamber 13.
7 and a fuel injection nozzle 18 having a fuel injection nozzle 7.

The cavity 11 has a circular shape in plan view,
The bottom surface 19 is formed so that it is deepest in the vicinity of the peripheral side wall 12, monotonically inclined upward toward the center, and becomes shallowest at a position directly below the fuel injection nozzle 18. The peripheral side wall 12 and the inner peripheral wall 14 are separated by a predetermined distance, and the outer combustion chamber 20 surrounding the inner combustion chamber 13 is defined between them.

The inner peripheral wall body 14 is formed in a circular shape concentric with the peripheral side wall 12, and a part of the inner peripheral wall body 14 is cut out at four equal intervals. In the present embodiment, as shown in FIG. 3, a notch 21 is formed which is cut in a rectangular shape from the upper end to the lower end.

The four first injection holes 16 of the fuel injection nozzle 18 are arranged so as to face the notch 21 and form the spray L ₁ which reaches the peripheral side wall 12 through the notch 21. Has become. Further, the second injection hole 17 has a cutout 21.
It is located toward the inner peripheral wall body 14 between. Therefore,
The second injection holes 17 and the first injection holes 16 are alternately added up at equal intervals.
It means that there are eight laps.

Then, as shown in FIG. 4, the second injection hole 17
Has an opening area smaller than that of the first injection hole 16 and forms a spray L ₂ which reaches the inner peripheral wall 14 and is ignited. Further, the air-fuel ratio (air / fuel) in the inner combustion chamber 13 is set so that the fuel is relatively rich so that the two-stage combustion is performed, as in the sub chamber of the known sub chamber internal combustion engine. Has become.

Next, the operation of the embodiment will be described.

At the timing when the piston 1 reaches the top dead center, fuel is injected from the injection holes 16 and 17 of the fuel injection nozzle 18 at a predetermined high pressure, and the spray L ₁ from the first injection hole 16 is reached.
Reaches the peripheral side wall 12 and is ignited in the vicinity thereof. At the same time, the spray L ₂ from the second injection hole 17 reaches the inner peripheral wall body 14 and is ignited. The gas in the inner combustion chamber 13 having a small air-fuel ratio is pushed out over the inner peripheral wall body 14 by the combustion pressure to become a total combustion, and a two-stage combustion without a sharp rise in the temperature gradient is performed and the unburned gas Are disturbed with the air together with the unburned matter in the outer combustion chamber 20, and the mixing is promoted. At this time, the exhaust gas is recirculated by the inclusion of the flame (burned gas), and the combustion temperature is lowered.

As described above, the inner combustion chamber 14 is erected in the cavity 11 to define the dual combustion chambers 13 and 20, and the fuel injection nozzle 18 having the injection holes 16 and 17 having different opening areas surrounds the combustion chambers. Since the fuel is injected into the side wall 12 and the inner peripheral wall body 14, the supplied fuel is simultaneously ignited at the radially outer side and the inner side in the cavity 11, and at the same time, mixed by two-stage combustion and flame blowing. Acceleration is made to achieve uniform and good combustion. That is, the reduction of smoke and particulates due to the high-pressure fuel injection and the reduction of NO _X are achieved. Then, due to the involvement of the flame, the internal EGR (Exhaust Gas)
Recirculation) acts, more of the NO _X reduction can be expected.

Next, a second embodiment of the present invention will be described with reference to FIGS.

In this embodiment, the notch 33 of the inner peripheral wall 32 of the combustion chamber 31 is formed by notching in a semicircular shape from the upper end (see FIG. 7). The size of the notch 33 corresponds to the size at the time when the spray L ₁ from the first injection hole 16 passes, and the action such as the two-stage combustion in the inner combustion chamber 13 is sufficiently exerted. You can do it.

Other constitutions and effects are the same as those of the first embodiment, and therefore, the same reference numerals are given and the description thereof will be omitted.

In the above first and second embodiments,
Although the upper opening edges of the combustion chambers 15 and 31 are formed to rise substantially vertically, like a known reentrant combustion chamber,
You may make it provide a shelf. In this case, as shown in FIG. 8, a configuration in which the shelf portion 42 is provided only on the inner peripheral wall body 41, a configuration in which the shelf portion 52 is provided only at the peripheral side wall 51 as shown in FIG. 9, and as shown in FIG. A configuration in which shelves 63 and 64 are provided on both the body 61 and the peripheral side wall 62 can be considered. These shelves 42, 52, 63, 64 form squish (air turbulence in the axial direction) of a predetermined strength at the end of the compression stroke in each combustion chamber 13, 20.
The mixing of fuel and air is further promoted, which contributes to good combustion.

Further, in the above embodiment, the combustion chamber divided by the circular cavity is shown, but the present invention can be applied to the rectangular cavity 71 as shown in FIG. In this case, the inner peripheral wall body 72 can be connected in a square shape similar to the peripheral wall 73 of the cavity 71, and a cutout portion 74 is formed at a corner portion thereof. Therefore, the internal combustion chamber 75 is also divided into a rectangular shape. The spray supply by the fuel injection nozzle (not shown) can be performed in the same manner as in the above embodiment. Further, as shown in FIG. 12, the circular cavity 1
The inner peripheral wall 72 having a square shape may be formed in one.

Next, a third embodiment of the present invention will be described with reference to FIGS.

In this embodiment, a trapezoidal projection 83 having a substantially flat upper surface 82 is provided at the central bottom portion of an inner combustion chamber 81 defined by an inner peripheral wall 32 similar to the second embodiment. The second injection hole 85 of the fuel injection nozzle 84
Are formed so as to face the protrusions 83.

With this structure, a part of the fuel is injected just below the fuel injection nozzle 84, collides with the upper surface 82 of the projection 83, and then is refracted substantially horizontally and scattered in the radial direction evenly. A horizontal spray L ₃ is formed. That is, atomization of the spray can be achieved without excessively increasing the injection pressure, and smoke and particulates can be reduced.

The other constructions and effects are the same as those of the second embodiment, so the same reference numerals are given and the description thereof is omitted.

Next, a fourth embodiment of the present invention will be described with reference to FIGS.

In this embodiment, a trapezoidal projection 91 similar to that of the third embodiment is provided in the central bottom portion of the inner combustion chamber 92 and faces the second injection hole 99 of the fuel injection nozzle 94. A groove 95 directed to a predetermined position of the inner peripheral wall body 94 is formed on the upper surface 93 which is a surface. The three first injection holes 97 of the fuel injection nozzle 96 are provided at equal intervals, and the cutout portions 98 of the inner peripheral wall body 94 are provided at three positions corresponding to the cutout portions 98, and the groove 95 is formed between these cutout portions 98. Radially extending from the center of the protrusion in three directions.

Therefore, the spray L _{1 from} the first injection hole 97 directly reaches the peripheral side wall 12, and the spray L ₄ from the second injection hole 99 which is directed directly below is collided with the upper surface 93 of the projection 91. The groove 95 is guided so as to be bent in three directions and reaches the inner peripheral wall body 94. Then, the gas in the inner combustion chamber 92 is pushed out over the inner peripheral wall body 94 to become the whole combustion, and the two-stage combustion without a sharp rise in the temperature gradient is performed, and the unburned portion thereof is unburned in the outer combustion chamber 20. Agitated with air along with the minutes to promote mixing.

As described above, in this embodiment, the radial spray can be formed in the inner combustion chamber 92 by the single second injection hole 99, and the direction and the scale of the spray (width in the circumferential direction).
Can be regulated by the groove 95. For example, as shown in FIG. 17, the groove 101 located on the upstream side of the swirl S is
Position 102 displaced from the middle position of the inner peripheral wall body 94 to the upstream side
In addition, the most downstream groove 103 is located at the position 104 displaced to the downstream side,
The grooves 105 between them are respectively directed to the intermediate position 106, and the thickness (width) of the grooves is made narrower toward the downstream side so that a relatively large spray L ₄ is formed on the strong swirl side. . This properly promotes the mixing of fuel and air by the swirl S.

Other functions and effects are similar to those of the first and second embodiments.

Next, a fifth embodiment of the present invention will be described with reference to FIGS.

In this embodiment, the same inner peripheral wall body 111 as that of the second embodiment is formed, and the fuel injection nozzle is also used.
The first injection hole 113 and the second injection hole 114 of 112 are horizontal fan-shaped spray L having a smaller vertical width with respect to the peripheral side wall 12 and the inner peripheral wall body 111.
₅ and L ₆ are formed. And inner wall
The notch 115 formed in 111 is elongated in the circumferential direction according to the spray L ₅ .

With this structure, the inner wall 91 can be formed relatively high even at the position where the spray L ₅ passes.
The two-stage combustion or the like by the inner combustion chamber 13 can be made to function more reliably.

The other constructions and effects are the same as those of the second embodiment, so the same reference numerals are given and the description thereof is omitted.

In the third to fifth embodiments, the shelves 42, 52, 63 and 6 shown in FIGS. 8 to 10 are also used.
4 can be provided, and it is also possible to apply to the rectangular cavity 71 or the inner combustion chamber 75 shown in FIGS. 11 and 12.

[0040]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) According to the configuration of claim 1, the injected fuel is simultaneously ignited inside and outside of the cavity in the radial direction, and the two-stage combustion and the flame blowout promote the mixing. Uniform and good combustion is achieved,
Smoke by the high-pressure fuel injection, with a reduction in particulates is achieved, reducing of the NO _X is achieved.

(2) According to the second aspect of the invention, the spray distribution in the inner combustion chamber can be easily adapted to swirl and the like, and good combustion can be promoted.

[Brief description of drawings]

FIG. 1 is a plan view showing a first embodiment of a direct injection internal combustion engine according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view taken along the line BB of FIG.

FIG. 4 is an enlarged view showing injection holes of the combustion injection nozzle of FIG.

FIG. 5 is a plan view showing a second embodiment of the present invention.

6 is a sectional view taken along the line CC of FIG.

7 is a sectional view taken along the line DD of FIG.

FIG. 8 is a cross-sectional view of essential parts showing another embodiment of FIGS. 2 and 6.

FIG. 9 is a cross-sectional view of essential parts showing another embodiment of FIGS. 2 and 6.

10 is a cross-sectional view of a main part showing still another embodiment of FIGS. 2 and 6. FIG.

11 is a plan view showing another embodiment of FIGS. 1 and 5. FIG.

12 is a plan view showing another embodiment of FIGS. 1 and 5. FIG.

FIG. 13 is a plan view showing a third embodiment of the present invention.

FIG. 14 is a cross-sectional view taken along the line EE of FIG.

FIG. 15 is a plan view showing a fourth embodiment of the present invention.

16 is a sectional view taken along line HH of FIG.

FIG. 17 is a plan view of a principal portion showing another embodiment of FIG.

FIG. 18 is a plan view showing a fifth embodiment of the present invention.

19 is a sectional view taken along the line FF of FIG.

FIG. 20 is a plan view showing a conventional direct injection internal combustion engine.

21 is a sectional view taken along the line GG of FIG.

[Explanation of symbols]

2 piston top 11 cavities 12 perimeter side wall 13 Inside combustion chamber 14 Inner wall 15 Combustion chamber 16 First injection hole 17 Second injection hole 18 Fuel injection nozzle 91 protrusion 95 groove

Claims (2)

[Claims] 1. A combustion chamber which defines an inner combustion chamber radially inward of a peripheral side wall of a cavity recessed in the top of the piston, and which has an inner peripheral wall body in which a part is appropriately cut out, A fuel injection nozzle having a first injection hole for injecting fuel to the peripheral side wall through a cutout portion of the peripheral wall body and a second injection hole having an opening area smaller than that of the first injection hole and facing the inner combustion chamber. A direct-injection internal combustion engine characterized by the above. 2. The inner combustion chamber has a protrusion provided so as to face the second injection hole, and a groove formed on an opposite surface of the protrusion and directed to an appropriate position of the inner peripheral wall body. The direct injection internal combustion engine according to claim 1.