JPH08200072A - Combustion chamber structure of indirect injection internal combustion engine - Google Patents

Abstract

PURPOSE: To improve a combustion chamber structure in an indirect injection internal combustion engine in order to reduce exhaust emission while improving combustion efficiency. CONSTITUTION: A combustion chamber structure which is composed of a guide groove part 3 and a vortex flow part 4 or the like or is composed of a jet colliding part and a recessed part or in which a projecting part is arranged in the recessed part or left and right recessed parts are arranged in line symmetry or the like, is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion chamber structure having a high air utilization rate for realizing a sub-chamber internal combustion engine having high combustion efficiency and low exhaust emission.

[0002]

2. Description of the Related Art FIG. 1 is a side sectional view showing a conventional combustion chamber structure of a sub-chamber internal combustion engine (Japanese Patent Publication No. 1-3100).
No. 5). Conventionally, as shown in FIG. 1, the cylinder head CH
Fuel is injected into the sub chamber (sub combustion chamber) SBR formed inside the fuel injection valve V, and the glow plug GP disposed in the sub chamber SBR causes the fuel to overheat and explode. Room SB
A combustion chamber (main combustion) formed in the crown portion of the piston P in the cylinder formed in the cylinder block CB through the injection hole G formed in the hot plug HP forming the bottom of the R and having an inclined shape in a side view. A chamber internal combustion engine having a structure in which flame is injected to the MBR and the air in the combustion chamber is further exploded to operate the piston P is known. (In Fig. 1,
The line A is the center line of the injection hole G, and the line A′-A ′ in FIG. 2A and the like is an extension line of the center line A in plan view. )

Among these, the combustion chamber (main combustion chamber) MBP of the crown of the piston P is a plan view of the piston crown showing the conventional combustion chamber structure of FIG. 2 (a), and (a) of (b). Medium A'-
As shown in the cross-sectional view taken along the line A ′, forward from the vicinity of the outlet of the injection hole G (hereinafter, in the plan view of the piston crown portion and the cross-sectional view taken along the line A′-A ′, the left side in the drawing is the front). The injection hole G
A guide groove 1 having a constant width for inducing a flame jet from is formed in a concave shape. On both sides of the guide groove, circular jet chambers 2 and 2 are formed in order to swirl the jet and mix it with unused air for combustion. It had a symmetrical concave structure. In this way, the combustion chamber MBP is formed into a “twisted flow” shape, and the “fuel injection system” such as the sub chamber SBP and the injection holes G is also improved so that the sub chamber having better starting performance and combustion performance than before. Has provided chamber internal combustion engines.

[0004]

However, the fuel consumption rate (combustion efficiency) and the exhaust emission (the general term for NO _x , HC, CO, PM, etc. contained in the exhaust gas) are further reduced. In order to realize this, in the "fuel injection system", it is necessary to improve so as to shorten the combustion period while suppressing rapid combustion, while the structure of the combustion chamber MBR directly related to combustion is It is necessary to make technical improvements in its size and shape.

Among these, the conventional combustion chamber MBR shown in FIG.
First, since the guide groove portion 1 guides the flame jet from the nozzle hole G forward with a constant width, the development of the flame in the direction perpendicular to the jet direction is suppressed. Therefore, the mixing with the air in the swirl chambers 2.2 is insufficient. Further, the front end of the guide groove portion 1 is up to the vicinity of the front and rear center of the crown portion of the piston P, and the jet flow becomes a dead end at this portion, and from this portion to the swirl chamber portions 2.2 on both sides of the guide groove portion 1. Is guided downward to the rear and faces the jet flow from the rear injection hole G, so the jet stays at this portion and incomplete combustion occurs, and the jet force is strong especially at high load. At times, there was a problem that exhaust emissions increased.

[0006]

The present invention uses the following means in order to solve the above problems. That is, in a sub-chamber internal combustion engine configured to inject fuel into a sub-chamber provided inside a cylinder head and to discharge a flame jet from the sub-chamber through a nozzle hole to a combustion chamber formed in a piston crown portion, The combustion chamber is provided with a groove portion having a flared end in a plan view in a front direction of the jet from a collision portion of the flame injection from the injection hole, and further, in front of the groove portion, one or a plurality of concave portions having a step with the groove. The structure was formed.

A sub-chamber internal combustion engine having a structure in which fuel is injected into a sub-chamber provided inside the cylinder head and a flame jet is discharged from the sub-chamber to a combustion chamber formed in the piston crown through injection holes. In the combustion chamber, the collision area of the flame injection from the injection hole is formed on the piston top surface, the area is made larger than the projected area of the injection hole outlet, and the piston crown is passed through the collision area. To the left and right of the jet direction,
In addition, the structure is such that a substantially fan-shaped concave portion that widens in the plan view is formed.

Further, in the combustion chamber structure of this sub-chamber type internal combustion engine, the piston top surface in the vicinity of the intersection of the front end edge of the recess with the extension line of the central axis of the injection hole in plan view is moved rearward. I made it stand out.

Further, in the combustion chamber structure of this sub-chamber internal combustion engine, the collision portion is recessed lower than the piston top surface and higher than the recess, and the bottom surface is inclined or parallel to the piston top surface. did.

A sub-chamber internal combustion engine having a structure in which fuel is injected into a sub-chamber provided inside the cylinder head and a flame jet is discharged from the sub-chamber through a nozzle hole to a combustion chamber formed in the crown of the piston. In the combustion chamber, the collision part of the flame injection from the injection hole is formed on the piston top surface or in an inclined shape, and the piston crown part is separated from the collision part and is line-symmetrical to both sides in the jet flow direction. It has a structure in which a concave portion is formed.

[0011]

[Function] A groove portion having a flared end in plan view is formed in the front direction of the jet from the collision portion of the flame injection from the injection hole, and one or a plurality of recesses having a step with the groove are formed in front of the groove portion. In the combustion chamber of the structure, as the jet flows forward in the groove, the jet flow also develops in the left-right direction, and the recess for vortexing the jet is provided in front of the groove, that is, in the extension of the jet. Therefore, the jet flow is smoothly introduced into the concave portion, swirled and burned without generating a place where the jet flow stays.

Further, the collision portion of the flame injection from the injection hole is formed on the top surface of the piston, and the area is made larger than the projected area of the outlet of the injection hole. In a combustion chamber of a structure that extends in the left-right direction of and has a substantially fan-shaped concave portion that widens in the plan view,
When the jet flow spreading from the collision site flows into the recess,
Since it is one step lower, a gap is created between the jet flow and the bottom surface of the cylinder head above it, and between the jet flow and the bottom surface of the recess, and the air in the gap is taken in to develop combustion, and the recess extends to the left and right long. Since it is ejected and it is wide at the end, the jet spreads smoothly in the left and right directions,
It can be thoroughly mixed with fresh air and burned.

In the combustion chamber of this structure, the piston top surface near the intersection of the front end edge of the recess with the extension line of the central axis of the injection hole in plan view is projected rearward. The jet flow that hits the front end of the recess splits into left and right, promoting swirlization in the left and right regions of the recess to develop combustion.

Further, in the combustion chamber of this structure, the impinging portion is recessed lower than the piston top surface and higher than the recessed portion, and the bottom surface is inclined or parallel to the piston top surface, so that the jet flow is increased. In the collision area of 1, the jet flow is suppressed from developing backward from the injection hole and is guided forward to promote the introduction of the jet flow into the recess.

Further, the collision portion of the flame injection from the injection hole is formed on the piston top surface or in an inclined shape,
In a combustion chamber having a structure in which concave portions are formed on both sides in the jet direction in a line-symmetrical manner, separating the collision portion, the jet flows from the main stream of the jet that advances forward from the injection holes into the left and right concave portions, and the left and right sides are sufficiently As a result of effective air mixing, a wide combustion space can be secured.

[0016]

The problems and configurations to be solved by the present invention are as described above, and the embodiments of the present invention shown in the accompanying drawings will be described below. FIG. 3A is a plan view of a piston crown portion showing an embodiment of a combustion chamber structure including a guide groove portion and a swirl chamber portion,
(B), (c) and (d) show various examples of the bottom shape of the guide groove portion and the swirl chamber portion. (A) is a sectional view taken along the line A'-A 'in FIG. Similarly, a plan view of a piston crown portion showing one embodiment, (b) is a sectional view taken along the line A′-A ′ in (a),
FIG. 5A is a plan view of the piston crown portion similarly showing an embodiment, FIG. 5B is a sectional view taken along line A′-A ′ in FIG.
7A is a plan view of a piston crown portion showing the same embodiment, FIG. 7B is a sectional view taken along the line A′-A ′ in FIG. 7A, and FIG. The plan view of the piston crown portion shown in the figure, (b) is a sectional view taken along the line A'-A 'in (a), and (a) of FIG. 8 is one embodiment of a combustion chamber structure including a jet impingement portion and a diverging concave portion. The top view of the piston crown part which shows an example, (b)
1A is a sectional view taken along the line A'-A 'in FIG. 9A, FIG. 9 is a partial side sectional view showing the flow of a jet flow in the combustion chamber structure of FIG.
1 (a) to 1 (d) are plan views of a piston crown portion showing an embodiment of a combustion chamber structure including a jet impingement portion and a concave portion, FIG.
(A) of FIG. 1 is a plan view of a piston crown part showing an embodiment of a combustion chamber structure in which a projecting part is provided in the combustion chamber structure consisting of the jet impingement part and the diverging concave part of FIG. 8, and (b) is ,
12A is a cross-sectional view taken along the line A′-A ′, FIG. 12A is a plan view of the piston crown portion showing the same embodiment, and FIG.
13A is a sectional view taken along the line A′-A ′ in FIG. 13A, and FIG.
2 is a plan view of a piston crown portion of a combustion chamber structure showing an embodiment of a combustion chamber structure in which a jet impingement portion in the combustion chamber structure of 2 is recessed,
(B) is a cross-sectional view taken along the line A'-A 'in (a) in the case where the bottom surface of the jet impingement portion is a horizontal plane, and (c) is A'- in the case (a) when the bottom surface is also an inclined surface. FIG. 14A is a cross-sectional view taken along the line A ′, FIG.
(A) middle A'-A 'line sectional view when the bottom surface of the jet impingement part is made horizontal, and (c) is a (a) middle A'-A' line sectional view when the bottom surface is also an inclined surface. , Fig. 15
(A) is a plan view of a piston crown portion showing an embodiment of a combustion chamber structure in which line-symmetric left and right recesses are provided, and (b) is
(A) is a cross-sectional view taken along the line A'-A ', and (c) is the same as BB.
FIG. 16A is a plan view of the piston crown portion showing an embodiment of the combustion chamber structure in which the line-symmetrical left and right recesses are provided, and FIG. FIG. 15B is a plan view of the piston crown portion showing an embodiment of the combustion chamber structure in which the inclined portion is provided between the left and right recesses in the combustion chamber structure of FIG. 15, and FIG.
18A is a sectional view taken along the line BB, FIG. 18A is a plan view of the piston crown portion showing the embodiment, and FIG. A'-A 'line sectional view,
Similarly, (c) is a cross-sectional view taken along line BB, and (a) of FIG.
20B is a side sectional view showing the combustion chamber structure of the sub-chamber internal combustion engine when the upper surface of the piston is an inclined surface, FIG. 20B is a plan view of the piston crown portion, and FIG. FIG. 21 (b) is a plan view of the piston crown, and FIG. 21 (a) is a side view of the piston crown partially inclined. A sectional view, (b) is a plan view of the piston crown portion, (a) of FIG. 22 is a sectional view taken along the line A in FIG. 1 of a hod plug showing a conventional injection hole structure, and (b) is a similar injection hole outlet. Projection of Figure 2, Figure 2
3A is a sectional view taken along line A in FIG. 1 of a hod plug showing an embodiment of a nozzle hole structure with an enlarged outlet diameter, FIG. 3B is a projection view of the nozzle hole outlet, and FIG. Is a sectional view taken along the line A in FIG. 1 of a hot plug showing the same embodiment, (b)
25A is a projected view of the nozzle hole outlet, FIG. 25A is a sectional view taken along the line A in FIG. 1 of a hod plug showing an embodiment of the nozzle hole structure with an additional nozzle hole, and FIG. FIG. 2C is a side sectional view of the hot plug, FIG.
6A is a sectional view taken along line A in FIG. 1 of the hot plug showing the embodiment, and FIG. 6B is a projection view of the nozzle hole outlet,
FIG. 3C is a side sectional view of the hot plug similarly.

First, in FIGS. 3 to 7, a guide groove portion 3 which is wide in plan view and which guides the flame jet is formed on the front side F of the collision site of the flame jet near the nozzle hole outlet G '. Disclosed is a combustion chamber MBR having a structure in which a swirl chamber portion for making a jet flow swirl to mix with air and combust it is connected in a concave shape to the front side F from the tip. Compared with the conventional combustion chamber MBR shown in FIG. 2, first, the guide groove portion 1 having a uniform width which hinders the jet flow development in the direction perpendicular to the jet flow direction is formed into a divergent guide groove 3. A jet flow in a right angle direction is developed as it goes forward (away from the nozzle hole outlet G ′). Since the swirl chambers 2 and 2 are arranged on both sides of the guide groove 1 whose front end is near the center of the crown of the piston P in the past, the jet flow near the front end of the guide groove 1 is provided. However, in the combustion chamber MBR shown in FIGS. 3 to 7, the swirl chamber is formed in front of the guide groove 3 so that the jet flow attempting to move forward is smoothly guided into the swirl chamber. , Fully vortexed in this, mixed with unused air,
It can produce highly efficient combustion.

The structure of the combustion chamber MBR shown in FIGS. 3 to 7 will be described. The combustion chamber MBR shown in FIG.
One swirl chamber portion 4 is provided in the front of the swirl chamber so that the jet flow developed forward is smoothly guided as it is into the swirl chamber portion 4 to be swirled. Further, the guide groove portion 3 and the swirl chamber portion 4 are provided with a step, and in the examples of (b) and (c), the guide groove portion 3 is deeper than the swirl chamber portion 4, and (d).
In the embodiment described above, the bottom surface is inclined so that the swirl chamber portion 4 is deepened and is deepened forward. Further, in the embodiment of (c), the bottom surface of the guide groove portion 3 is inclined forward.

In the structure shown in FIG. 4, in the front of the guide groove portion 3, the guide groove portion 3 is branched in a curved shape on both sides to form swirl chamber portions 3a, 3a. The jet flow goes straight forward in the guide groove portion 3 while spreading right and left, then splits into both sides by hitting the curved portion at the front end of the swirl chamber portions 3a, 3a, and swirls at the tip-shaped convex portion in plan view. To mix with air. It differs from the combustion chamber structure shown in FIG. 3 in that the jet flow is split left and right.

In the combustion chamber MBR shown in FIG. 5, two left and right swirl chamber portions 5, 5 having a semicircular shape in plan view and an inclined bottom surface are recessed from the front end of the guide groove portion 3, and further in front thereof. Similarly, the vortex flow chamber portion 5a having the inclined bottom surface is provided as a recess. Among the jets that flow straight forward in the guide groove 3, the jets near the left and right ends are split into left and right to be swirled in the swirl chambers 5 and 5, and the jet that further straightens in the guide groove 3. Are configured to enter the swirl chamber portion 5a and become a swirl flow.
Develop sufficient combustion in a.

In the combustion chamber MBR shown in FIG. 6, the front end of the guide groove portion 3 is circularly extended to the left and right so that the swirl chamber portions 3b and 3b are formed.
Is formed, and a swirl chamber portion 6 that is shallower than the guide groove portion 3 and the swirl chamber portions 3b and 3b is provided in the front thereof.
Further, in the one shown in FIG. 7, the left and right corners of the front end of the guide groove portion 3 are circularly extended to the left and right to form swirl chamber portions 3c, 3c, and between the swirl chamber portions 3c, 3c. , The guide groove 3
Also, a circular swirl chamber 7 having a shallower depth than the swirl chambers 3c and 3c is provided as a recess. That is, in both cases, the front end of the guide groove 3 is extended to the left and right to form the vortex chambers 3b and 3c in order to make the left and right split flows of the jet vortex, and the jet flow that is still going straight ahead in the guide groove 3 is formed. Is guided to the swirl chambers 6 and 7 to make it swirl.

Next, the combustion chamber MBR shown in FIG. 8 will be described. The jet impingement portion 8 having a larger area than the projected area of the injection hole outlet G ′ is formed in a semicircular shape having a constant radius from the center of the injection hole outlet G ′ on the top surface of the piston P. A substantially fan-shaped recess having a shape that extends in the left-right direction of the crown portion of the piston P forward through the jet impingement portion 8 and that has its left and right ends flared toward the outer periphery of the top surface of the piston P. 9
Is formed.

With such a structure, as shown in FIG. 9, the jet F is jetted from the injection hole G and first collides with the jet collision portion 8 and moves forward (left and right) on the jet collision portion 8. Proceed to and enter the recess 9 which is one step lower. At this time, since the jet impinging portion 8 at a high position, that is, the jet F enters from the upper side while descending slightly, the air below the jet F in the concave portion 9 and the air in front of the jet F as well as the jet F upward. Intake air from the gap created between the cylinder head CH,
Develop combustion. That is, an air layer is generated above and below the jet F. This means that when the jet P directly contacts the piston P, the surface temperature of the piston P cools the flame and causes the formation of soot. It also eliminates the problem of being easily invited. Further, if the jet impingement portion 8 is smaller than the projected area of the nozzle hole outlet G ′, that is,
If the concave portion 9 overlaps with the projected portion of the injection hole outlet G ′, the direct injection from the injection hole G directly collides with the bottom surface of the concave portion 9, and the jet flow colliding with the bottom surface goes upward from below. As we try to proceed, we will face the jet from above,
Jet development is hindered. For this reason, the area of the jet impingement portion 8 is set as described above.

Further, the jet flow tends to develop in a divergent shape as shown by the arrow in FIG. 8, and by forming the concave portion 9 in a divergent shape in a plan view, the tendency of the jet flow is not hindered. Combustion can be developed and it extends long in the left-right direction, so that a sufficient combustion space can be provided in the left-right direction.

10A to 10D, the combustion chamber MBR shown in FIG. 8 and the jet impinging portion 8 have the same structure, and the shape of the concave portion 9 is changed to form the concave portions 9a, 9b. 9c, 9d
It is what All of the recesses 9a to 9d are common in that they extend to the left and right for a long time in order to develop combustion, and have a divergent shape toward the front.

The recess 9'of the combustion chamber MBR shown in FIG.
In the recess 9 in the illustrated combustion chamber MBR, in order to split the jet flow to the left and right to make it a vortex, the front end edge portion of the intersection with the extension line A ′ of the injection hole center line A is rearward, that is, the injection. The protruding portion 10 is formed by protruding toward the hole G. By splitting the jet flow into the left and right, the jet flow is smoothly developed in the left and right regions within the recess, and combustion is further developed. Similarly, the concave portion 9e of the combustion chamber MBR shown in FIG. 12 also forms the projecting portion 10, and the front end edges of the concave portion 9e on both sides of the projecting portion 10 are curved to facilitate swirling. As a result, jet development to the left and right regions is further promoted.

The combustion chamber MBR of FIG. 13 is shown in FIGS.
In the illustrated combustion chamber structure, the jet impingement portion 8 is
It is shallower than the recess, and the bottom surface is horizontally recessed, or (b)
As described above, the jet impingement portion 8'is deeply inclined forward. This is intended to suppress the development of the jet flow F ′ toward the rear side of the nozzle hole outlet G ′ and to introduce more jet flow into the recess. The recess shown in FIG. 13 uses the recess 9e shown in FIG. Of course, FIGS.
2. In order to maintain the same effect as the jet flow introduction into the recess shown in the figure, the jet impingement portion 8'is shallower than the recess 9e.

The combustion chamber MBR shown in FIG. 14 is provided with a jet jet impingement portion 8 "having a slanted or horizontal bottom surface as in the case of FIG. 13, but its front end shape is as shown in FIGS. Differently, it has a straight line on the left and right, and in front of it,
A lower recess 11a having a shape in which semicircular recesses are connected to the left and right is provided to be deeper than the jet combustion chamber 8 "and to divide the jet left and right, and in front of the left and right semicircular portions. In order to further promote the swirling of the jet, the upper recesses 11b, 11b shallower than the lower recess 11a are provided.

FIG. 15 shows an extension line A'of the center line A of the injection hole G.
The main flow of the jet flow traveling upward is introduced forward at the top surface of the piston P, and in the middle thereof, the jet flow is introduced into the left and right recessed portions 12, 12 which are concavely formed on both sides in a line-symmetrical manner.・ 1
It is configured such that the jet stream is mixed with air and burned in the chamber 2. The shapes of the left and right recesses are as shown in FIG.
Left and right recesses 12a, 12a, 12 in (b) and (c)
Those like b.12b, 12c.12c are conceivable.

FIG. 17 shows the left and right recesses 12-1 shown in FIG.
In the combustion chamber MBR in which 2 is recessed, in order to smoothly guide the main stream of injection to the front, the inclined portion 13 is deeper than the rear.
Is provided. In addition, FIG.
12 is recessed, and an inclined portion 14 is provided at the passage portion of the main stream of the jet from the front and rear central portions.

19 to 20 show a structure in which the combustion chamber MBR is formed by the shape of the piston crown portion itself. FIG.
Is an inclined surface 15 having a constant angle on the entire upper surface of the piston P. In FIG. 20, the rear surface from the front-rear center line B, that is, the surface including the jet collision portion from the injection hole is the horizontal surface 16, and the front surface is the inclined surface 17. Similarly, in FIG. 21, an inclined concave portion 18 is provided in front of the front and rear central piece B. All of these slopes 15, slopes 17, and sloped recesses 18 are inclined forward, that is, on the side opposite to the injection hole G, that is, the injection hole outlet G ′.
The volume of the combustion chamber in the vicinity is small, and the volume of the combustion chamber on the side opposite to the injection hole outlet G'is large. When a jet flow is emitted from the injection hole G to the crown portion of the piston P having such a configuration, as shown in FIG. 19B, first, in the vicinity of the injection hole outlet G ′ where the volume of the combustion chamber is small, the jet flow that collides with the piston crown portion. As the jet F expands and swells to the left and right, the jet F
The air travels forward with a large volume, and in this portion, the air accumulated in the space around the jet F reacts with the jet and burns. That is, the portion of the piston crown portion close to the injection hole G is used for diffusion of the jet flow, and the opposite side of the injection hole G is used for combustion.

Above, the description of the improvement of the combustion chamber MBR, that is, the main combustion chamber is completed, and next, of the improvements of the fuel injection system, the improvement of the injection hole G will be described. Conventional injection hole G
As shown in FIG. 22, is on the left and right of the circular main injection hole 19,
It had a cross-sectional shape in which the small circular sub-injection holes 20, 20 were connected. The cross-section from the inlet portion near the bottom of the sub chamber SBR to the outlet portion near the piston crown portion has the same shape and the same area.

Thus, the cross section from the inlet to the outlet is
If they have the same shape and the same area, the jet flow ejected from the nozzle hole outlet has a strong directivity to the jet collision part of the cylinder crown, and the jet spreads in the cylinder crown forming the combustion chamber. It shows a difficult tendency. Further, the strong jetting direction means that the jetting speed is high. If the jetting speed is too fast, the temperature of the cylinder and the piston rises, which adversely affects the piston drive. Therefore, in order to prevent the injected jet flow from smoothly diffusing in the main combustion chamber and to prevent the jet speed from being too fast, the outlet side sectional area of the injection hole G is set to the inlet side sectional area. It is configured to be larger than that. In this embodiment, first, in the injection hole G shown in FIG. 23, the left and right of the main injection hole 19 in the front sectional view taken along the line A shown in FIG.
°), and the left and right width at the outlet is longer than that at the inlet to form a main injection hole 19 '. In addition, in the injection hole G shown in FIG. 24, in addition to the main injection hole, the auxiliary injection hole 20.
20 is also expanded to the left and right by a constant angle (for example, 5 °), and the left and right widths at the outlet are longer than those at the inlet.
It is set to 0 '・ 20'. In this way, by widening the shape of the injection hole in the left and right, the downward directionality of the jet flow ejected is relaxed, the diffusivity is improved, and combustion is promoted.

Further, as a result of connecting the auxiliary injection hole to the main injection hole, there is a difference in the velocity of the jets flowing through the main injection hole and the auxiliary injection hole,
This will form a vortex at the time of flame injection,
It is linked to the development of jet diffusion and combustion. In order to increase the effect of this sub injection hole, in the injection hole G shown in FIG. 25 and FIG. 26, other sub injection holes are added in addition to the conventional two left and right sub injection holes 20. That is, in FIG. 25, one sub-injection hole 21 is formed in a portion which becomes the apex portion of the main injection hole 19 in the jet flow direction, and in FIG. 26, a portion in which the sub-injection hole 21 is arranged in FIG. The auxiliary injection holes 22 and 22 are arranged between the left and right auxiliary injection holes 20 and 20. In both cases, since the vortexing of the jet flow is generated in front of the jet flow, both the sub injection holes 21 and 22 are formed on the front side of the main injection hole 19.

[0035]

The present invention has the following effects due to the above configuration. That is, the combustion chamber structure configured in the piston crown portion, so as not to hinder the spread of the jet flow ejected from the injection hole in the left-right direction, and to allow the jet flow to smoothly flow into the recess forming the vortex, Further, since the vortex flow forming portion is provided in a sufficient space on the crown portion of the piston, the air can be sufficiently mixed with the flame injection from the injection hole and can be burned in a form close to complete combustion, so that the combustion efficiency is high, Moreover, it is possible to provide a sub-chamber internal combustion engine with low exhaust emission.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a conventional combustion chamber structure of a sub-chamber internal combustion engine.

FIG. 2A is a plan view of a piston crown portion showing a conventional combustion chamber structure. (B) is a sectional view taken along the line A'-A 'in (a).

FIG. 3A is a plan view of a piston crown portion showing an embodiment of a combustion chamber structure including a guide groove portion and a swirl chamber portion.
(B) is a sectional view taken along the line A'-A 'in (a) showing various examples of bottom shapes of the guide groove portion and the swirl chamber portion. (C)
FIG. 6A is a sectional view taken along the line A′-A ′ in (a) showing various examples of the bottom shapes of the guide groove portion and the swirl chamber portion. (D) shows various examples of the bottom shapes of the guide groove and the swirl chamber (a).
It is a middle A'-A 'line sectional view.

FIG. 4 (a) is a plan view of a piston crown portion showing the same embodiment. (B) is a sectional view taken along the line A'-A 'in (a).

FIG. 5 (a) is a plan view of a piston crown portion showing the same embodiment. (B) is a sectional view taken along the line A'-A 'in (a).

FIG. 6 (a) is a plan view of a piston crown portion showing the same embodiment. (B) is a sectional view taken along the line A'-A 'in (a).

FIG. 7 (a) is a plan view of the piston crown portion showing the same embodiment. (B) is a sectional view taken along the line A'-A 'in (a).

FIG. 8A is a plan view of a piston crown portion showing an embodiment of a combustion chamber structure including a jet impingement portion and a diverging concave portion. (B) is a sectional view taken along the line A'-A 'in (a).

9 is a partial side sectional view showing a flow of a jet flow in the combustion chamber structure of FIG.

FIG. 10A is a plan view of a piston crown portion showing an embodiment of a combustion chamber structure including a jet collision portion and a concave portion.
FIG. 3B is a plan view of the piston crown portion showing the same embodiment. FIG. 6C is a plan view of the piston crown portion showing the same embodiment. FIG. 6D is a plan view of the piston crown portion showing the same embodiment.

11A is a plan view of a piston crown portion showing an embodiment of a combustion chamber structure in which a projecting portion is provided in the combustion chamber structure including the jet impingement portion and the diverging concave portion of FIG. 8. FIG.
(B) is a sectional view taken along the line A'-A 'in (a).

FIG. 12 (a) is a plan view of a piston crown portion showing the same embodiment. (B) is a sectional view taken along the line A'-A 'in (a).

13 (a) is a plan view of a piston crown portion of the combustion chamber structure showing an embodiment of the combustion chamber structure in which the jet impinging portion in the combustion chamber structure of FIG. 12 is recessed. (B) is a cross-sectional view taken along the line A'-A 'in (a) when the bottom surface of the jet impingement portion is a horizontal surface. FIG. 6C is a sectional view taken along the line A′-A ′ in FIG.

FIG. 14A is a plan view of a piston crown portion showing an embodiment of a combustion chamber structure in which a jet impingement portion is recessed. (B)
FIG. 6A is a sectional view taken along the line A′-A ′ in (a) in the case where the bottom surface of the jet impingement portion is horizontal. FIG. 6C is a sectional view taken along the line A′-A ′ in FIG.

FIG. 15 (a) is a plan view of a piston crown portion showing an embodiment of a combustion chamber structure in which line-symmetric left and right recesses are provided. (B) is a sectional view taken along the line A'-A 'in (a).
Similarly, (c) is a BB line sectional view.

FIG. 16 (a) is a plan view of a piston crown portion showing an embodiment of a combustion chamber structure in which line-symmetrical left and right recesses are provided. FIG. 3B is a plan view of the piston crown portion showing the same embodiment. FIG. 6C is a plan view of the piston crown portion showing the same embodiment.

17 (a) is a plan view of a piston crown portion showing an embodiment of a combustion chamber structure in which an inclined portion is provided between left and right recesses in the combustion chamber structure of FIG. 15. FIG. (B) is A'-A 'in (a)
It is a line sectional view. Similarly, (c) is a BB line sectional view.

FIG. 18 (a) is a plan view of a piston crown portion showing the same embodiment. (B) is a sectional view taken along the line A'-A 'in (a). Similarly, (c) is a BB line sectional view.

FIG. 19 (a) is a side sectional view showing a combustion chamber structure of the sub-chamber internal combustion engine when the upper surface of the piston is inclined. (B) is a plan view of the piston crown portion.

20A is a side sectional view of the same when a part of the upper surface of the piston is inclined, and FIG. 20B is a plan view of the crown portion of the piston.

FIG. 21 (a) is a side sectional view of the same when a part of the piston crown is concavely formed. (B) is a plan view of the piston crown portion.

22 (a) is a sectional view taken along line A in FIG. 1 of a conventional hod plug showing a conventional injection hole structure. (B) is a projection view of the nozzle hole outlet.

23A is a cross-sectional view taken along line A in FIG. 1 of a hod plug showing an embodiment of a nozzle hole structure with an enlarged outlet diameter. FIG.
(B) is a projection view of the nozzle hole outlet.

FIG. 24 (a) is a sectional view taken along line A in FIG. 1 of the hot plug showing the same embodiment. (B) is a projection view of the nozzle hole outlet.

25A is a cross-sectional view taken along line A in FIG. 1 of a hod plug showing an embodiment of a nozzle hole structure in which a sub nozzle hole is added. FIG.
(B) is a projection view of the nozzle hole outlet. (C)
Similarly, it is a side sectional view of a hot plug.

FIG. 26 (a) is a sectional view taken along line A in FIG. 1 of the hot plug showing the same embodiment. (B) is a projection view of the nozzle hole outlet. FIG. 3C is a side sectional view of the hot plug similarly.

[Explanation of symbols]

 CH Cylinder head CB Cylinder block P Piston V Fuel injection valve SBR Sub chamber (sub combustion chamber) GP Glow plug HP Hot plug G Nozzle G'Nozzle outlet MBR Combustion chamber (main combustion chamber) 3 Guide groove 3a, 3b, 3c Vortex chamber part 4, 5, 6, 7 Vortex chamber part 8.8 ', 8 "Jet impingement part 9 Recessed parts 9a, 9b, 9c, 9d Recessed part 10 Projected part 11a Lower recessed part 11b Upper recessed part 12 Left and right recessed parts 12a, 12b 12c Left and right recesses 13 ・ 14 Sloping part 15 Sloping surface 16 Horizontal surface 17 Sloping surface 18 Sloping recessed part 19 ・ 19 'Main injection hole 20 ・ 20' Sub injection hole 21 ・ 22 Sub injection hole

Claims (5)

[Claims] 1. A sub-chamber internal combustion engine configured to inject fuel into a sub-chamber provided inside a cylinder head and to discharge a flame jet from the sub-chamber to a combustion chamber formed in a piston crown through a nozzle hole. In the combustion chamber, in the front of the jet flow from the collision site of the flame injection from the injection hole, a groove portion that widens toward the end in plan view is recessed, and in front of it, one or a plurality of steps having the groove and the step are formed. A combustion chamber structure for a sub-chamber internal combustion engine, which is characterized in that a concave portion is formed. 2. A sub-chamber internal combustion engine configured to inject fuel into a sub-chamber provided in a cylinder head and to discharge a flame jet from the sub-chamber to a combustion chamber formed in a piston crown portion through a nozzle hole. In the combustion chamber, the collision area of the flame injection from the injection hole is formed on the piston top surface, the area is made larger than the projected area of the injection hole outlet, and the piston crown is passed through the collision area. A combustion chamber structure of an internal combustion engine of a sub-chamber type, characterized in that a substantially fan-shaped recess extending in the left-right direction of the jet direction and widening in a plan view is formed in the portion. 3. The combustion chamber structure for a sub-chamber internal combustion engine according to claim 2, wherein the piston top surface near the intersection of the front end edge of the recess with the extension line of the central axis of the injection hole in plan view is provided. , A combustion chamber structure of an internal combustion engine of a subchamber type, characterized in that it is projected rearward. 4. The combustion chamber structure for a sub-chamber internal combustion engine according to claim 3, wherein the collision site is lower than the piston top surface,
A combustion chamber structure for an internal combustion engine of a sub-chamber type, characterized in that the recess is formed higher than the recess, and the bottom surface is inclined or parallel to the piston top surface. 5. A sub-chamber internal combustion engine configured to inject fuel into a sub-chamber provided in a cylinder head and to discharge a flame jet from the sub-chamber to a combustion chamber formed in a piston crown portion through a nozzle hole. In the combustion chamber, the collision part of the flame injection from the injection hole is formed on the piston top surface or in an inclined shape, and the piston crown part is separated from the collision part and is line-symmetrical to both sides in the jet flow direction. A combustion chamber structure for a sub-chamber internal combustion engine, characterized in that a recess is formed in the interior.