JP3185234B2 - Direct injection internal combustion engine - Google Patents

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 and burned.

[0002]

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

As shown in FIGS. 14 and 15, a conventional direct injection type internal combustion engine of this type is provided in a combustion chamber 3 which is appropriately recessed and formed in a top portion 2 of a piston 1 and in a cylinder head 4. A fuel injection nozzle 5 for injecting fuel into the combustion chamber 3 is provided. At the tip of the fuel injection nozzle 5, an injection hole 7 appropriately formed so as to face the peripheral side wall 6 of the combustion chamber 3 is formed, and a fuel pump (not shown) is formed.
Is injected at a predetermined pressure. The shape of the fuel spray L is adapted to the shape of the combustion chamber 3 so as to be evenly distributed in any direction as much as possible. The injected fuel is appropriately mixed with the air introduced into the combustion chamber 3 and ignited from the tip side (near the peripheral side wall 6) of the spray L, and combustion proceeds to the center (near the fuel injection nozzle 5). Thus, desired combustion can be obtained.

[0004] Further, in order to obtain good combustion by mixing the spray L and air well, various configurations have been proposed for generating appropriate turbulence (swirl, squish) in the air in the combustion chamber 3.

[0005]

In recent years, it has been practiced to increase the injection pressure as much as possible in order to completely atomize the fuel and obtain combustion with low smoke and particulates. However, if the injection pressure is excessively increased, there is a problem that uniform combustion is not performed and NOx due to high-temperature combustion is generated.

In view of the above circumstances, the present invention has been devised to provide a direct injection internal combustion engine capable of reducing smoke and particulates and simultaneously reducing NOx.

[0007]

According to the present invention, there is provided a combustion chamber in which deep portions and shallow portions are alternately arranged in circumferentially divided regions, a vertical injection hole for axially diffusing fuel into the respective regions, and And a fuel injection nozzle in which horizontal injection holes that diffuse in the radial direction are alternately faced.

[0008]

According to the above construction, in the combustion chamber, a swirl in the circumferential direction and a squish in the axial direction are obtained in the intake stroke and the compression stroke, and turbulence of air flowing along the bottom of the combustion chamber from a deep part to a shallow part is obtained. And promotes mixing of the fuel spray with the air. Then, the fuel injection nozzle distributes the fuel in the form of a spray diffused vertically and horizontally in the combustion chamber, and achieves uniform and good combustion in combination with the turbulence of the air.

[0009]

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

FIGS. 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 chamber 15 having regions 11, 12, 13, and 14 equally divided in the circumferential direction, and four injection holes 16, 1 facing the respective regions 11.
And a fuel injection nozzle 20 having 7, 18, and 19 fuel injection nozzles.

The combustion chamber 15 is formed on the top 22 of the piston 21 to have a circular shape in plan view.
Numeral 4 has a fan shape with a central angle of 90 degrees. Each of the regions 11... 14 has a deep portion 24 having a relatively large height up to the deepest portion of the bottom surface 23, and a bottom surface 25 which is larger than the deep portion 24.
And shallow portions 26 whose height is small are alternately arranged. In this embodiment, the maximum height of the deep portion 24 is formed so as to be approximately twice the maximum height of the shallow portion 26. These bottom surfaces 23 and 25 are formed so as to be deepest in the vicinity of the peripheral side wall 27 of the combustion chamber 15, monotonically upward toward the center, and shallowest at a position directly below the fuel injection nozzle 20.

The fuel injection nozzle 20 is located at the center of the combustion chamber 15 and has four injection holes which are vertically flat,
19 and laterally flat horizontal injection holes 16 and 18 are alternately provided. That vertical injection hole 17 and 19, the fuel is diffused in the axial direction being adapted to form a spray L ₁ in the longitudinal fan, horizontal injection holes 16 and 18, the horizontal sector by diffusing the fuel in the circumferential direction so as to form a spray L _2.
In the present embodiment, the vertical injection holes 16 and 18 are formed in the deep portion 24.
The horizontal injection holes 17 and 19 face the respective peripheral side walls 27 in the shallow part 26.

Further, as shown in FIG.
At the boundary (boundary line) 28 of the deep part 24 and the shallow part 26
A substantially vertical step portion 29 is formed due to the difference in depth between the steps.

Next, the operation of the first embodiment will be described.

In the intake stroke, air entering from an intake port (not shown) becomes a turbulence flowing along the peripheral side wall 27 of the combustion chamber 15, and a swirl S that turns around an axis is formed. At the end of the compression stroke, air between the upper surface of the piston 21 and the lower surface of the cylinder head 4 is pushed out toward the combustion chamber 15, and mainly the bottom surface 23 of the deep portion 24.
The turbulence flows upward from above, and a squish K is formed along the peripheral side wall 27 in the axial direction. Then, the axial flow of air flows along the bottom surface 25 of the shallow portion 26 beyond the step portion 29, and becomes a turbulent bottom portion flowing upward in the circumferential direction as indicated by an arrow T in FIG.

At the timing when the piston 21 reaches the top dead center, fuel is injected at a predetermined pressure from each of the injection holes 16... 19 of the fuel injection nozzle 20, and a vertical fan-shaped flat spray L ₁ is injected into the deep portion 24. Also, the horizontal fan-shaped flat spray L ₂
Is supplied. Mixing of these sprays L ₁ and L ₂ with air is promoted by swirl S, squish K and bottom turbulence T, and the spray shape is a combination of a vertical fan shape and a horizontal fan shape. The fuel distribution becomes uniform, and the desired combustion proceeds.

As described above, the deep portions 24 and the shallow portions 26 are alternately arranged in the circumferential direction in the combustion chamber 15, and the vertical fan-shaped spray L ₁ is provided in the deep portion 24, and the horizontal fan-shaped spray L ₂ is provided in the shallow portion 26. Since the fuel injection nozzle 20 to be formed is provided, an air flow (T) along the bottom surfaces 23 and 25 of the combustion chamber 15 is formed in addition to the swirl S and the squish K, and the mixing of fuel and air is promoted. In addition, uniform combustion is performed, so that smoke and particulates are reduced by high-pressure fuel injection, and NOx is reduced.

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

In this embodiment, the combustion chamber 1 formed by arranging the deep part 24 and the shallow part 26 in the same manner as in the previous embodiment.
5, the horizontal injection holes 16 and 18 are provided in the deep portion 24 and the
6 is provided with a fuel injection nozzle 31 facing the vertical injection holes 17 and 19, respectively. Therefore deep 24
Spray L ₂ of the flat transverse fan next to it, also so that the flat spray L ₁ vertically is formed in the shallow portion 26. Although the initial fuel distribution differs from that of the first embodiment, the swirl, squish and bottom turbulence (not shown) formed in the same manner promote the mixing of the fuel and the air, and achieve uniform combustion. Is achieved.

Since the other constructions and functions and effects are the same as those of the first embodiment, the same reference numerals are given and the explanation is omitted.

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

This embodiment has a fuel injection nozzle 43 provided with circular injection holes 41 and 42 for forming conical spray, instead of the vertical injection holes 17 and 19 of the second embodiment. Things. Therefore, a horizontal fan-shaped fuel spray L ₂ is formed in the deep portion 24 of the combustion chamber 15, and a conical fuel cone L ₃ is formed in the shallow portion 26.
The other configuration and operation and effect are the same as those of the second embodiment.

FIGS. 8 and 9 show circular injection holes 41 and 42 in place of the horizontal injection holes 16 and 18 in the first embodiment.
Are those in which the fuel injection nozzle 51 having a shows a fourth embodiment which is arranged, the vertical sector of the fuel spray L ₁ deep 24 of the combustion chamber 15, the spray L ₃ of conical shallow 26 Each is formed. The other configuration and operation and effect are the same as those of the first embodiment.

As described above, various combinations of injection holes are conceivable, and any combination of injection holes may be used as long as fuel can be diffused in the axial direction or the radial direction. For example, elliptical (elliptical) injection holes can be used. It is also conceivable to combine holes as appropriate.

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

In this embodiment, as in the first embodiment, a combustion chamber 62 in which a shelf 61 is formed along the opening edge of a combustion chamber in which a deep portion 24 and a shallow portion 26 are arranged. It is a thing. The overhang length of the shelf 61 is the depth 2
4 at the center of the regions 12 and 14,
Are formed so as to be minimum (0) at the center positions of the regions 11 and 13, and the tip of the shelf 61 is formed so as to draw an ellipse when viewed from above. With this configuration, a strong squish in the deep part 24 is obtained,
Mixing of the fuel sprays L ₁ , L ₂ and air is further promoted, and good combustion is obtained.

Since the other constructions and functions and effects are the same as those of the first embodiment, the same reference numerals are given and the explanation is omitted.

FIGS. 12 and 13 show a sixth embodiment having a combustion chamber 62 in which a shelf 61 is provided in the combustion chamber of the second embodiment. As in the fifth embodiment, an elliptical shape extends from the deep part 24 to the shallow part 26. Other configurations, functions and effects are the same as those of the second and fifth embodiments.

In the above-described embodiment, the combustion chamber has the four equally divided regions 11... 14. However, the combustion chamber is divided into regions of different sizes, and the deep part and the shallow part are arranged respectively. However, it is conceivable to adjust the fuel spray shape according to the volume. In addition to a round combustion chamber, a square combustion chamber may be used.

[0031]

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

A combustion chamber in which deep portions and shallow portions are alternately arranged in regions divided in the circumferential direction, and vertical injection holes for axially diffusing fuel and horizontal injection holes for radially diffusing fuel in each region. Since the fuel injection nozzle is provided with a swirl and a squish, a turbulent flow is formed along the bottom surface of the combustion chamber to promote mixing of the fuel and air and to perform uniform combustion, thereby increasing the pressure. Reduction of smoke and particulates due to fuel injection is achieved, and reduction of NOx is achieved.

[Brief description of the 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 line AA of FIG. 1;

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a plan view showing a second embodiment of the present invention.

FIG. 5 is a sectional view taken along line CC of FIG. 4;

FIG. 6 is a plan view showing a third embodiment of the present invention.

FIG. 7 is a sectional view taken along line DD in FIG. 6;

FIG. 8 is a plan view showing a fourth embodiment of the present invention.

FIG. 9 is a sectional view taken along line EE of FIG. 8;

FIG. 10 is a plan view showing a fifth embodiment of the present invention.

FIG. 11 is a sectional view taken along line FF of FIG. 10;

FIG. 12 is a plan view showing a sixth embodiment of the present invention.

13 is a sectional view taken along line GG of FIG.

FIG. 14 is a plan view showing a conventional direct injection internal combustion engine.

FIG. 15 is a sectional view taken along the line HH in FIG. 14;

[Explanation of symbols]

11, 12, 13, 14 Area 15 Combustion chamber 16, 18 Horizontal injection hole (injection hole to diffuse fuel in the radial direction) 17, 19 Vertical injection hole (injection hole to diffuse fuel in the axial direction) 20 Fuel injection nozzle 24 Deep 26 shallow

Continuation of the front page (56) References JP-A-64-29616 (JP, A) JP-A-1-116220 (JP, A) JP-A-59-173554 (JP, A) Jpn. , U) Real opening 58-165263 (JP, U) Real opening Hei 1-61427 (JP, U) Real opening 63-160373 (JP, U) Real opening 51-61426 (JP, U) Real opening 62-176478 (JP, U) Japanese Utility Model Showa 52-162302 (JP, U) JP-B 43-20403 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02B 23/00 -23/10 F02M 61/18

Claims (1)

(57) [Claims] 1. A combustion chamber in which deep portions and shallow portions are alternately arranged in circumferentially divided regions, a vertical injection hole for axially diffusing fuel in each of the regions, and a horizontal injection hole for radially diffusing fuel. A direct injection type internal combustion engine comprising: