JP2005048717A - Swirl chamber type combustion chamber of diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a swirl chamber type combustion chamber of a diesel engine, heightening the utilization factor of air in the central part of a swirl chamber through an auxiliary communicating hole. <P>SOLUTION: In this swirl chamber type combustion chamber of a diesel engine, a lower wall 10 of a mouthpiece is provided with at least a pair of right and left auxiliary communicating holes 12, 12. Supposing that a spherical body 15 is formed around the central point 7c of an upper opening surface 7b of a recess 7a of the mouthpiece 7, and when the length of the radius of the upper opening surface 7b of the recess 7a of the mouthpiece 7 is taken as 100%, the length of the radius of the spherical body 15 is set to 70%, the respective auxiliary communicating holes 12 are directed so that the swirl chamber side extension line 12b of the central axis 12a of each auxiliary communicating hole passed through the inside of the spherical body 15. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

    The present invention relates to a vortex chamber combustion chamber of a diesel engine.

A conventional vortex chamber combustion chamber of a diesel engine is shown in FIG. 10 (see, for example, Patent Document 1).
This is as follows.
As shown in FIG. 10 (B), the top dead center direction of the piston (102) in the cylinder (101) is up, the bottom dead center direction is down, the cylinder center axis (103) is close, and the cylinder peripheral wall (104) The front is the front.
An upward concave portion (106) is provided in the lower portion of the cylinder head (105) above the cylinder peripheral wall (104), and a base (107) is fitted into the inlet of the concave portion (106) so that the upper portion of the concave portion (106) faces upward. The depression (106a) and the downward depression (107a) in the base (107) form a swirl chamber (108), the main combustion chamber (109) is formed in the cylinder (101), and the base lower wall (110) A nozzle hole (111) is provided on the rear side, and the nozzle hole (111) is inclined upward from the main combustion chamber (109) toward the vortex chamber (108), and the main combustion chamber (109) is inclined at the nozzle hole (111). The torsion chamber (108) is in communication.
A pair of left and right auxiliary communication holes (112) and (112) are provided in the lower wall (110) of the base, and each auxiliary communication hole (112) is separated from the injection hole (111), and as shown in FIG. When viewing (107) from directly above, each auxiliary communication hole (112) is distributed so as to be on both sides of the vortex chamber side extension line (114) of the nozzle center axis (113).

However, this prior art is different from the present invention in the following points.
Assuming a sphere (115) centered on the center point (107c) of the upper opening surface (107b) of the recess (107a) of the base (107), the upper opening surface (107b) of the recess (107a) of the base (107). When the radius of each of the spheres (115) is 70% and the radius of each of the auxiliary communication hole central axes (112a) is extended to the vortex chamber side extension line (112b), the sphere (115) Each auxiliary communication hole (112) is oriented so as to pass outside. A sphere (115) having a radius of 70% is an outer one of the double spheres shown in FIGS. 10 (A) and 10 (B).

  In this prior art, the auxiliary air pushed into the vortex chamber (108) from each auxiliary communication hole (112) in the compression stroke does not reach the central portion of the vortex chamber (108) and affects the air in this portion. I can't. For this reason, the utilization rate of the air in the central portion of the vortex chamber (108) cannot be increased by the auxiliary communication hole (112).

  Further, in this prior art, as shown in FIG. 10A, when the base (107) is viewed from directly above, the center (112c) of the upper opening of each auxiliary communication hole (112) has a radius of 50%. Each auxiliary communication hole (112) is arranged so as not to overlap the spherical body (15). The sphere (115) having a radius of 50% is the inner one of the double spheres shown in FIGS.

  In this prior art, when the base (107) is viewed from directly above, the center (112c) of the upper opening of each auxiliary communication hole (112) is far away from the center of the vortex chamber (108). Even if the auxiliary communication holes (112) are oriented in the vertical direction, the vortex chamber side center extension line (112b) of each auxiliary communication hole (112) cannot pass through the sphere (115) having a radius of 50%. In FIG. 10 (B), the vortex chamber side center extension line (112b) of the auxiliary communication hole (112) when the auxiliary communication holes (112) are oriented in the vertical direction is shown as the original vortex chamber side extension line (112b). It is shown on the right side.

JP-A-7-97924 (see FIGS. 7 and 8)

  This invention makes it a subject to provide the vortex chamber type combustion chamber of a diesel engine which can solve the said problem.

(Invention according to claims 1 to 6)
The inventions according to claims 1 to 6 are inventions relating to the orientation and arrangement of the auxiliary communication holes (see FIGS. 1 and 7 to 9).
In the invention according to claim 1, assuming a sphere (15) centering on the center point (7c) of the upper opening surface (7b) of the recess (7a) of the base (7), the recess (7a) of the base (7) is assumed. ) Where the radius of the upper opening surface (7b) is 100%, the radius of the sphere (15) is 70%,
As shown in FIGS. 1 and 7 to 9 (B) and (D), the vortex chamber side extension line (12b) of each auxiliary communication hole central axis (12a) passes through the sphere (15). Thus, each auxiliary communication hole (12) is oriented.

  In the inventions according to claim 2 and claim 3, the radius of the sphere (15) is 60% and 50% respectively.

  In the invention according to claim 4, as shown in the respective partial views (A) of FIGS. 1 and 7 to 9, when the base (7) is viewed from directly above, the top of each auxiliary communication hole (12). Each auxiliary communication hole (12) is arranged so that the center (12c) of the opening overlaps the sphere (15) having a radius of 50%.

  The inventions according to claims 5 and 6 are inventions related to limiting the inclination angle of each auxiliary communication hole (12) with respect to the vertical direction. In the invention according to claim 4, each of the components shown in FIGS. As shown in FIG. (B), the angle of inclination when the base (7) is viewed from the side is 30 ° or less. In the invention according to claim 5, each of the partial views (D of FIG. 1 and FIGS. ), The inclination angle when the base (7) is viewed from directly behind is set to be 15 ° or less.

The exact definitions of key terms used in claims 1-6 and other claims are as follows.
The nozzle center axis (13) refers to the main nozzle center axis (17a) when the nozzle (11) includes a side nozzle (18).
“Directly above” refers to the direction parallel to the cylinder center axis (3) and the top dead center of the piston (2).
Directly behind is the direction parallel to the bottom surface (7d) of the base, and the direction in which the nozzle center axis (13) advances from the vortex chamber (8) to the main combustion chamber (9) when the base (7) is viewed from directly above. Say.
The term “straight side” refers to a direction that is parallel to the bottom surface (7d) of the base and is orthogonal to the back side.
The up / down, front / rear and left / right directions are defined based on the direction of the cylinder center axis (3) and the direction of the nozzle center axis (13), and the up / down direction does not always mean the vertical direction. The front-rear direction does not always mean the horizontal direction. For this reason, the present invention is not limited to a vertical engine in which the cylinder is directed in the vertical direction, but is also applied to a horizontal engine in which the cylinder is directed in the horizontal direction and an inclined engine in which the cylinder is inclined.

(Inventions according to claims 7 and 8)
The inventions according to claims 7 and 8 are inventions related to a device for the size of the auxiliary communication hole (12).
In the invention according to claim 7, the minimum passage cross-sectional area of the nozzle (11) is set to 100%, the total of the minimum passage cross-sectional areas of the pair of auxiliary communication holes (12) (12) is set to 3 to 15%, In the invention according to claim 8, this is set to 4 to 10%.

(Invention according to claims 9 to 14)
The invention which concerns on Claims 9-14 is an invention regarding the device of the structure of a nozzle (11).
In the inventions according to claims 9 to 14, as shown in FIGS. 2 (A) to (D), the injection hole (11) is composed of a main injection hole (17) and a pair of left and right side injection holes (18) and (18). The side nozzle holes (18) communicate with the main nozzle holes (17) on the peripheral side of the main nozzle holes (17).

(Invention according to claims 15 to 18)
The invention according to claims 15 to 18 is a combination of the invention according to claim 1 with the invention specific matters of the inventions according to claims 5 to 7, 9, and 14.

(Inventions according to claims 19 and 20)
The inventions according to claims 19 and 20 are inventions related to the orientation of the auxiliary communication hole (12). As shown in the respective partial views (B) and (D) of FIGS. When viewed from directly behind, each auxiliary communication hole (12) rises vertically from the base lower surface (7d).

(Claims 21-24)
As shown in FIGS. 1, 7, and 2, the inventions according to claims 21 to 24 include the invention specific matters of the inventions according to claims 19, 20, 7, 9, and 14 as shown in FIG. It relates to a combined invention.

(Claims 25-28)
The inventions according to claims 25 to 28 are inventions related to the orientation of the pair of auxiliary communication holes (12) and (12) in the inventions according to claims 1 to 18.
The invention according to claim 25 or 26 comprises a pair of left and right auxiliary communication holes (12), (12) as shown in each of FIGS. 8 (A) to 9 (C), and the main combustion chamber (9). It is inclined upward or backward toward the vortex chamber (8).
The invention according to claim 27 or 28 is a pair of left and right auxiliary communication holes (12) when the base (7) is viewed from the rear side as shown in each of the partial views (D) of FIGS. The distance of (12) is such that it gradually becomes shorter or longer as it goes upward.

(Invention of Claim 1)
The invention according to claim 1 has the following effects 1 and 2.
<< Effect 1 >> The utilization rate of the air at the center of the vortex chamber can be increased by the auxiliary communication hole.
In the invention according to claim 1, the radius of the sphere (15) is set to 70%, and each auxiliary communication hole center axis (12a) is formed as shown in the respective partial views (B) and (D) of FIGS. The auxiliary communication holes (12) are oriented so that the extension line (12b) of the vortex chamber passes through the sphere (15). For this reason, in the compression stroke, auxiliary air that is pushed from the main combustion chamber (9) into the vortex chamber (8) through the auxiliary communication holes (12) is pushed from the nozzle (11) into the vortex chamber (8). The vortex flow is disturbed and the vortex flow is disturbed, and reaches the center of the vortex chamber (8). The air in this portion is disturbed, and the mixing of the air and the injected fuel is facilitated. Plan. Thus, the utilization rate of the air at the center of the vortex chamber (8) can be increased by the auxiliary communication hole (12).

<< Effect 2 >> The utilization rate of the air at both sides of the vortex chamber can be increased by the auxiliary communication hole.
In the invention according to claim 1, as shown in the respective partial views (A) of FIGS. 1 and 7 to 9, when the base (7) is viewed from directly above, each auxiliary communication hole (12) is formed at the nozzle hole. It distributed so that it might come to both sides of the center axis line (12a) or its extension room side extension line (12b). For this reason, in the compression stroke, auxiliary air that is pushed from the main combustion chamber (9) into the vortex chamber (8) through the auxiliary communication holes (12) is pushed from the nozzle (11) into the vortex chamber (8). It penetrates both sides of the flow, causes turbulence in both sides of the vortex, disturbs the air on both sides of the vortex chamber (8), and helps to mix this air with the injected fuel. In this way, the utilization rate of the air at both sides of the vortex chamber (8) can be increased by the auxiliary communication hole (12).

(Invention according to claims 2 to 6)
In the inventions according to claims 2 and 3, the radius of the sphere is set to 60% and 50%, respectively, so that the effect 1 is further ensured.

  In the invention according to claim 4, as shown in the respective partial views (A) of FIGS. 1 and 7 to 9, when the base (7) is viewed from directly above, the top of each auxiliary communication hole (12). Each auxiliary communication hole (12) was arranged so that the center (12c) of the opening overlapped the sphere (15) having a radius of 50%. Therefore, not only when each auxiliary communication hole (12) is oriented in the vertical direction, but also when each auxiliary communication hole (12) is inclined to some extent with respect to the vertical direction, each auxiliary communication hole central axis ( The extension line (12b) of the vortex chamber 12a) surely passes through the central portion of the vortex chamber (8), and the effect 1 is further ensured.

  In the inventions according to claims 5 and 6, as shown in the respective partial views (B) and (D) of FIGS. 1 and 7 to 9, each auxiliary communication hole (12) has a small inclination angle with respect to the vertical direction. Compared to the case where the inclination angle is large, the auxiliary communication hole (12) can be shortened, the passage resistance of the auxiliary air is reduced, and the above effect 1 is further ensured.

(Inventions according to claims 7 and 8)
The invention according to claims 7 and 8 has the following effect 3.
<< Effect 3 >> The overall performance of the exhaust gas can be enhanced by the auxiliary communication hole.
In the invention according to claim 7, since the minimum passage sectional area of the nozzle hole (11) is set to 100%, the total of the minimum passage sectional areas of the pair of auxiliary communication holes (12) and (12) is set to 3 to 15%. The auxiliary communication hole (12) can sufficiently reduce one of the generation amounts of nitrogen oxide and smoke without greatly increasing one, and can improve the overall performance of exhaust gas.
The reason can be considered as follows.
If the total is less than 3%, the passage resistance of the auxiliary communication hole (12) becomes too large, the amount of auxiliary air pushed in is insufficient, the diffusion of the injected fuel in the vortex chamber (8) becomes insufficient, and the vortex chamber ( 8) It is considered that a local high temperature portion is generated in 8), and the amount of nitrogen oxide generated is not sufficiently reduced. On the other hand, if the total exceeds 15%, the amount of vortex flow from the nozzle (11) is insufficient by the amount of increase in the amount of auxiliary air, and the amount of air and injected fuel in the vortex chamber (8) is reduced. It is considered that mixing becomes poor, combustion deteriorates, and the amount of smoke generated does not decrease sufficiently. On the other hand, if the total is set to 3 to 15%, such a defect does not occur, so that it is considered that the overall performance of the exhaust gas can be improved.
In the invention which concerns on Claim 8, since the said sum was set to 4 to 10%, the said effect 3 becomes more reliable, and it becomes also possible to reduce each generation amount of a nitrogen oxide and smoke.
The generation amounts of nitrogen oxides and smoke are generally in a contradictory relationship, and if one decreases, the other tends to increase, and both decrease is an epoch-making phenomenon. The reason why such a phenomenon occurs is that the air in the center of the vortex chamber (8) is disturbed by the auxiliary air flow, so that the injected fuel is diffused widely into the vortex chamber (8), and the vortex chamber (8) While the local temperature rise at the center is avoided and the generation amount of nitrogen oxides is reduced, the mixing of the air and the injected fuel in the vortex chamber (8) is also improved, the combustion is improved, and the generation amount of smoke is simultaneously increased. This is considered to be reduced.

(Invention according to claims 9 to 14)
<< Effect 4 >> The side nozzle hole can further increase the utilization rate of air in the vortex chamber.
In the inventions according to claims 9 to 14, as shown in FIGS. 2 (A) to (D), the injection hole (11) is composed of a main injection hole (17) and a pair of left and right side injection holes (18) and (18). The side nozzle holes (18) communicate with the main nozzle holes (17) on the peripheral side of the main nozzle holes (17). For this reason, the side vortex flow pushed from the side nozzle (18) into the vortex chamber (8) passes along the left and right sides of the main vortex flow pushed from the main nozzle (17) into the vortex chamber (8) in the compression stroke. And the utilization factor of the air of the right and left both sides of a vortex chamber (8) can be raised more.
The reason for this is that due to the difference in passage resistance between the main nozzle hole (17) and the side nozzle hole (18), the main vortex flow and the side vortex flow are displaced from each other, and a micro vortex is generated between them. This is thought to be because the air in the left and right sides of the vortex chamber (8) is disturbed to increase the utilization rate of the air here.

  In the invention according to claim 10, as shown in FIG. 2 (A), when the mouthpiece (7) is viewed from the side in a direction orthogonal to the main nozzle center axis (17a), each side nozzle center axis (18a) Since the side nozzle holes (18) are arranged so that is located behind the central axis of the main nozzle hole (17a), the utilization rate of air at the center of the vortex chamber (8) is increased. This is presumably because minute vortexes are generated near the center of the vortex chamber (8).

  In the invention according to claim 11, as shown in FIG. 2 (A), the elevation angle of each side nozzle center axis (18a) is smaller than the elevation angle of the main nozzle center axis (17a). Colliding with the vortex from behind, the air utilization rate in the vortex chamber (8) increases. This is thought to be because micro vortices are generated in the vortex chamber due to the collision of the side vortex flow.

  In the invention according to claim 12, as shown in FIG. 2 (D), the distance between the pair of left and right side nozzle center axes (18a) and (18a) is gradually narrowed toward the front. The utilization rate of air in the vortex chamber (8) is increased. This is presumably because micro vortices are generated in the vortex chamber (8) due to the collision between the side vortex flows.

  In the invention according to the thirteenth aspect, as shown in FIGS. 2B to 2D, the passage cross-sectional area of each side injection port (18) is gradually reduced toward the front. ) Will increase the air utilization rate. This is considered to be because the speed at which the side vortex flow collides with the main vortex flow increases, and the generation of micro vortex in the vortex chamber (8) is promoted.

  In the invention according to claim 14, as shown in each partial view (A) of FIG. 1 and FIGS. 7 to 9, when the base (7) is viewed from directly above, the top of each auxiliary communication hole (12). Since each auxiliary communication hole (12) is arranged so that each side injection hole (18) is positioned at a position that is retracted from the opening parallel to the central axis (13) of the main injection hole, the air in the vortex chamber (8) The utilization rate increases. This is presumably because the auxiliary air flow collides with the side vortex flow and micro vortex is generated in the side vortex flow.

(Invention according to claims 15 to 18)
The inventions according to claims 15 to 18 exhibit the effects of the inventions according to claims 4 to 6, 9, and 14 according to the invention-specific matters.

(Inventions according to claims 19 and 20)
<Effect> The utilization rate of air in the center of the vortex chamber can be further increased by the auxiliary communication hole.
In the inventions according to claims 19 and 20, as shown in the respective partial views (B) and (D) of FIGS. 1 and 7, each auxiliary communication hole (12 ) Stand up in the vertical direction, the auxiliary communication hole (12) can be shorter than in the case of being inclined, and the auxiliary air passage resistance is reduced. ) The air utilization rate in the central part can be further increased.

(Inventions according to claims 21 to 24)
According to the inventions according to claims 21 to 24, the effects obtained in claims 19, 20, 7, 9, and 14 can be obtained according to the specific matters of the invention.

(Invention according to claims 25 to 28)
In the invention according to claim 25, as shown in FIGS. 8A to 8C, the pair of left and right auxiliary communication holes (12), (12) are directed from the main combustion chamber (9) to the vortex chamber (8). Since it is inclined upward, the collision angle of the auxiliary air against the vortex flow is small, and the flow velocity of the vortex flow is difficult to decrease.

  In the invention according to claim 26, as shown in FIGS. 9A to 9C, the pair of left and right auxiliary communication holes (12) and (12) are directed from the main combustion chamber (9) to the vortex chamber (8). Since it is tilted upward and inclined, the collision of the auxiliary air flow against the vortex flow becomes close to a frontal collision, and micro vortex tends to occur in the vortex flow.

  In the invention according to claim 27, as shown in FIG. 8 (D), when the base (7) is viewed from the back side with the nozzle hole (11) facing forward, a pair of left and right auxiliary communication holes (12) ( Since the auxiliary communication holes (12) are oriented so that the separation distance of 12) gradually decreases as it goes upward, the auxiliary air moves toward the center of the vortex chamber (8), and the vortex chamber (8) The utilization rate of air in the center increases.

  In the invention according to claim 28, as shown in FIG. 9 (D), when the base (7) is viewed from the back side with the nozzle hole (11) in front, the pair of left and right auxiliary communication holes (12) ( 12) Since each auxiliary communication hole (12) is oriented so that the distance between them increases gradually as it goes upward, the auxiliary air faces both sides of the vortex chamber (8), and the vortex chamber ( The utilization factor of air on both sides of 8) is increased.

Embodiments of the present invention will be described with reference to the drawings.
1-6 is a figure explaining the vortex chamber type combustion chamber of the vertical diesel engine which concerns on 1st Embodiment. FIG. 7 illustrates the second embodiment, FIG. 8 illustrates the third embodiment, and FIG. 9 illustrates the fourth embodiment.

According to the present invention, an auxiliary communication hole (12) is provided in a base (7) provided with an injection hole (11), and the auxiliary communication hole (12) allows air in the central part of the vortex chamber (8) and both the left and right lateral parts to be supplied. In order to increase the utilization rate, the arrangement and orientation of the auxiliary communication holes (12), the size of the auxiliary communication holes (12), and the structure of the nozzle holes (11) are devised.
The first embodiment shown in FIG. 1 relates to a device having a pair of auxiliary communication holes (12) and (12) in a vertical direction, and the second embodiment shown in FIG. 7 is a pair of auxiliary communication holes in a vertical direction. Regarding the one provided with the holes (12) and (12), the third embodiment shown in FIG. 8 and the third embodiment shown in FIG. 9 are provided with a pair of auxiliary communication holes (12) and (12) in an oblique direction. About things.

A first embodiment shown in FIGS. 1 to 6 will be described.
As shown in FIG. 3 (B), the top dead center direction of the piston (2) in the cylinder (1) is up, the bottom dead center direction is down, the cylinder center axis (3) is rearward, and the cylinder peripheral wall (4) An upward concave portion (6) is provided in the lower part of the cylinder head (5) above the cylinder peripheral wall (4), and a base (7) is fitted into the inlet of the concave portion (6). The dent chamber (8) is formed by the upward recess (6a) and the downward recess (7a) in the base (7), and the main combustion chamber (9) is formed in the cylinder (1). A nozzle hole (11) is provided on the rear side of the lower wall (10). The nozzle hole (11) is inclined upward from the main combustion chamber (9) toward the vortex chamber (8). The combustion chamber (9) communicates with the vortex chamber (8). The base lower surface (7d) is on a plane orthogonal to the cylinder center axis (3).

  As shown in FIG. 3 (A), the fuel injection nozzle (19) and the heat plug (20) face the vortex chamber (8). A fan-shaped gas guide groove (21) is provided on the top surface of the piston (2) as viewed from directly above. The gas guide groove (21) is located at a lower portion of the fan (11), and the gas guide groove (21) becomes wider and gradually shallower as the distance from the nozzle (11) increases.

The principle of combustion in this vortex chamber combustion chamber is as follows.
In the compression stroke, as the piston (2) rises, compressed air is pushed into the vortex chamber (8) from the main combustion chamber (9) through the nozzle hole (11), and this vortexes in the vortex chamber (8). When fuel is injected from the fuel injection nozzle (19) in the vicinity of the top dead center of the piston (2), this fuel is caught in the vortex flow and ignited while mixing with the air in the vortex chamber (8). It burns in the spiral chamber (8). The combustion expansion gas generated in the vortex chamber (8) by this combustion is ejected from the vortex chamber (8) to the main combustion chamber (9) through the injection port (11) together with unburned fuel. The gas jet spouted into the main combustion chamber (9) gradually increases in width and gradually rises by the guidance of the gas guide groove (21). The fuel contained in the gas jet ignites and burns while mixing with the air in the main combustion chamber (9).

The arrangement and orientation of the auxiliary communication holes (12) are as follows.
As shown in FIGS. 1 (A) to (D), a pair of left and right auxiliary communication holes (12) and (12) are provided in the lower base wall (10), and each auxiliary communication hole (12) is connected to the nozzle hole (11). As shown in FIG. 1 (A), when the base (7) is viewed from directly above, each auxiliary communication hole (12) is connected to the vortex chamber side extension line (14) of the nozzle center axis (13). Distributing to be on both sides. Depending on the shape of the nozzle hole (11), each auxiliary communication hole (12) can be distributed so as to be on both sides of the nozzle hole central axis (13).

  As shown in FIGS. 1 (A), (B), and (D), assuming a sphere (15) centered at the center point (7c) of the upper opening surface (7b) of the recess (7a) of the base (7), The radius of the upper opening surface (7b) of the recess (7a) of the base (7) is 100%, the radius of the sphere (15) is 50%, and the vortex of each auxiliary communication hole center axis (12a) Each auxiliary communication hole (12) is oriented so that the room-side extension line (12b) passes through the sphere (15).

  By such orientation of the auxiliary communication hole (12), the auxiliary air pushed into the vortex chamber (8) from the main combustion chamber (9) through the auxiliary communication hole (12) in the compression stroke is admitted into the vortex chamber (8). The center of the vortex chamber (8) is used to increase the utilization rate of air. From this point of view, the assumed radius of the sphere (15) is desirably 70%, more desirably 60%, and most desirably 50%. FIGS. 1A, 1B, and 1D show a triple sphere 15 whose radii are 70%, 60%, and 50% in order from the outside.

  As shown in FIG. 1A, when the base (7) is viewed from directly above, the center (12c) of the upper opening of each auxiliary communication hole (12) overlaps the sphere (15) having a radius of 50%. Thus, each auxiliary communication hole (12) is arranged. Such an arrangement of the auxiliary communication holes (12) ensures that the vortex chamber side extension line (12b) of each auxiliary communication hole central axis (12a) passes through the central portion of the vortex chamber (8). From this viewpoint, the radius of the sphere (15) where the center (12c) of the upper opening of each auxiliary communication hole (12) overlaps is desirably 70%, more desirably 60%, and most desirably 50%. When viewed from directly above the mouthpiece (7), the upper opening of each auxiliary communication hole (12) is located directly to the left and right of the upper opening of the main nozzle (17).

  As shown in FIGS. 1 (A) and 1 (D), a pair of left and right vertical reference lines (16) extending directly above the center (12c) of the upper opening of the pair of left and right auxiliary communication holes (12) and (12). 16), as shown in FIG. 1 (B), when the nozzle (7) is viewed from the side in a direction orthogonal to the nozzle center axis (13), the vortex of each auxiliary communication hole center axis (12a) Each auxiliary communication hole (12) is oriented so that the room-side extension line (12b) overlaps with each vertical reference line (16). Further, as shown in FIG. 1D, when the base (7) is viewed from directly behind the nozzle hole (11), the extension line on the vortex chamber side of each auxiliary communication hole central axis (12a) ( Each auxiliary communication hole (12) is oriented so that 12b) overlaps each vertical reference line (16).

  By such orientation of each auxiliary communication hole (12), each auxiliary communication hole (1) can be shorter and the passage resistance of the auxiliary air is smaller than when the inclination angle with respect to the vertical direction is large. From this point of view, as shown in FIG. 1 (B), when the base (7) is viewed from the side in a direction orthogonal to the nozzle center axis (13), the vortex chamber of each auxiliary communication hole center axis (12a). Each auxiliary communication hole (12) is oriented so that the side extension line (12b) forms an angle of 30 ° or less with each vertical reference line (16), and as shown in FIG. When the base (7) is viewed from directly behind (11), the vortex chamber side extension line (12b) of each auxiliary communication hole central axis (12a) is connected to each vertical reference line (16). It is desirable to orient each auxiliary communication hole (12) so as to form an angle of 15 ° or less. The former angle is more preferably 15 ° or less and the latter angle is more preferably 8 ° or less. The former angle is more preferably 8 ° or less, and the latter angle is more preferably 4 ° or less. Most preferably, the angle is 4 ° or less and the latter angle is 2 ° or less.

  The chain lines shown before and after the vertical reference line (16) in FIG. 1 (B) are lines that form an angle of 30 ° with the vertical reference line (16). In addition, the chain lines shown on the left and right of the vertical reference line (16) in FIG. 1D are lines that form an angle of 15 ° with each vertical reference line (16).

The setting of the size of the auxiliary communication hole (12) is as follows.
The minimum passage cross-sectional area of the nozzle hole (11) is 100%, and the total of the minimum passage cross-sectional areas of the pair of auxiliary communication holes (12) and (12) is 6.0%. The minimum passage cross-sectional areas of the pair of auxiliary communication holes (12) and (12) are equal.
By setting the size of the auxiliary communication hole (12), the pushing amount of the auxiliary air and the vortex flow can be obtained without excess or deficiency, and one of the generation amounts of nitrogen oxides and smoke is not greatly increased. The other can be sufficiently reduced, and the overall performance of the exhaust gas can be enhanced. From this point of view, the total is preferably set to 3-15%, more preferably 4-10%, even more preferably 6-10%, and 7-9%. Is most desirable.

The structure of the nozzle hole (11) is as follows.
As shown in FIGS. 2A to 2D, the nozzle hole (11) is composed of a main nozzle hole (17) and a pair of left and right side nozzle holes (18) (18), and each side nozzle hole (18) is a main nozzle hole. It communicates with the main nozzle hole (17) on the peripheral side of (17). As shown in FIG. 2A, when the mouthpiece (7) is viewed from the side in a direction orthogonal to the main nozzle center axis (17a), each side nozzle center axis (18a) is the main nozzle center axis (17a). The side nozzle holes (18) are arranged so as to be further rearward, and the elevation angle of each side nozzle center axis (18a) with respect to the base lower surface (7d) is smaller than the elevation angle of the main nozzle center axis (17a). In addition, each side nozzle hole (18) is oriented. The elevation angle of the main nozzle center axis (17a) is 45 °.

  As shown in FIGS. 2 (B) to (D), the side nozzle holes (18) are arranged such that the distance between the pair of left and right side nozzle center axes (18a) (18a) gradually decreases toward the front. ). As shown in FIGS. 2 (B) to 2 (D), the passage cross-sectional area of each side nozzle hole (18) is gradually reduced toward the front. As shown in FIG. 1 (A), when the base (7) is viewed from directly above, the upper opening of each auxiliary communication hole (12) retreats directly behind in parallel with the main nozzle center axis (13). Each side nozzle hole (18) is arranged so that each side nozzle hole (18) is located.

The exhaust gas characteristics of the combustion chamber according to the first embodiment are as follows.
As shown in FIG. 4, the combustion chamber according to the first embodiment generates less nitrogen oxide than the combustion chamber of Comparative Example 1. In Comparative Example 1, the auxiliary communication hole (12) and the side injection hole (18) are removed from the combustion chamber of the first embodiment. From comparison with Comparative Example 1, it can be seen that the generation amount of nitrogen oxides is reduced by providing the auxiliary communication hole (12) and the side injection port (18).

  As shown in FIG. 5, in the combustion chamber according to the first embodiment, both the amounts of nitrogen oxide and smoke generated at a predetermined load are reduced compared to the combustion chambers of Comparative Example 1 and Comparative Example 2. In Comparative Example 2, an auxiliary communication hole (12) is added to Comparative Example 1. 1st Embodiment is corresponded to what added the side nozzle (18) to the comparative example 2. FIG. From the comparison between Comparative Example 1 and Comparative Example 2, it can be seen that the above-described reduction function can be obtained by adding the auxiliary communication hole (12). Moreover, it turns out from the comparison with the comparative example 2 and 1st Embodiment that the said reduction function increases by addition of a side nozzle hole (18).

Such exhaust gas characteristics are greatly related to the passage cross-sectional area of the auxiliary communication hole (12).
Each horizontal axis in FIGS. 6A to 6C shows the total ratio of the minimum passage cross-sectional areas of the pair of auxiliary communication holes (12) and (12) when the minimum cross-sectional area of the nozzle is defined as 100%. The vertical axis of FIG. 6 (A) shows the variation rate of the generation amount of nitrogen oxides, the vertical axis of FIG. 6 (B) shows the variation rate of the generation amount of smoke, and the vertical axis of FIG. The sum of both rates of change is shown. Each variation rate is calculated based on the amount of nitrogen oxide or smoke generated in the combustion chamber having no auxiliary communication hole (12) as a reference value. If the reference value is α and the variation value is β, the variation rate is represented by (β−α) / α.

  As shown in FIG. 6C, the absolute value of the sum of the reduction rates is the largest when the passage cross-sectional area is 7.7%. If the absolute value of the reduction rate here is 100%, The absolute value of the sum of the reduction rates exceeds 98% when the passage cross-sectional area is 7 to 9%, and the absolute value of the sum of the reduction rates exceeds 95% is the passage cross-sectional area of 6 to 6%. The absolute value of the sum of the reduction ratios exceeds 60% when the passage cross-sectional area is 3 to 15%. The absolute value of the sum of the reduction rates exceeds 70%, and both nitrogen oxide and smoke are effectively reduced when the passage cross-sectional area is 4 to 10%. Based on this comparison, the total of the minimum passage cross-sectional areas of the pair of auxiliary communication holes (12) (12) is preferably set to 3 to 15%, more preferably 4 to 10%, and more preferably 6 to 10%. It can be seen that it is more desirable to set to%, and it is most desirable to set to 7-9%.

Each combustion chamber according to the second embodiment shown in FIG. 7, the third embodiment shown in FIG. 8, and the fourth embodiment shown in FIG. 9 is different from the combustion chamber according to the first embodiment in the following points.
In the combustion chamber according to the second embodiment shown in FIG. 7, two pairs of left and right auxiliary communication holes (12) (12) are provided. Each of the auxiliary communication holes (12) has a minimum cross-sectional area of the nozzle (11) of 100% and the total of the minimum passage cross-sectional areas of the two pairs of auxiliary communication holes (12) and (12) is set to 8%. The minimum passage cross-sectional area is equal. Even in the second embodiment, the amount of nitrogen oxides generated is reduced as shown in FIG. Further, even in the second embodiment, both the generation amounts of nitrogen oxide and smoke at a predetermined load are reduced as compared with Comparative Example 1 and Comparative Example 2.

  In the combustion chamber according to the third embodiment shown in FIG. 8, as shown in FIG. 8B, the pair of left and right auxiliary communication holes (12) and (12) are changed from the main combustion chamber (9) to the vortex chamber (8). As shown in FIG. 8 (D), when the base (7) is viewed from directly behind the nozzle hole (11), the pair of left and right auxiliary communication holes (12) ( Each auxiliary communication hole (12) is oriented so that the mutual separation distance of 12) gradually decreases as it goes upward. The tilt angle in the forward direction is 30 °, and the tilt angle in the left-right direction is 15 °.

  In the combustion chamber according to the fourth embodiment shown in FIG. 9, as shown in FIG. 9B, the pair of left and right auxiliary communication holes (12) and (12) are changed from the main combustion chamber (9) to the vortex chamber (8). As shown in FIG. 9 (D), when the base (7) is viewed from directly behind the nozzle hole (11), the pair of left and right auxiliary communication holes (12) ( Each auxiliary communication hole (12) is oriented so that the mutual separation distance of 12) gradually increases as it goes upward. The inclination angle in the backward direction is 30 °, and the inclination angle in the left-right direction is 15 °.

Other configurations of the second to fourth embodiments are the same as those of the first embodiment.
7-9 which show 2nd-4th embodiment, the same code | symbol as 1st Embodiment is attached | subjected to the element same as 1st Embodiment.

FIG. 1A is a plan view, FIG. 1B is a cross-sectional view taken along line BB in FIG. 1A, and FIG. 1C is a diagram illustrating a base used in the first embodiment of the present invention. FIG. 1D is a bottom view, and is a cross-sectional view taken along line DD of FIG. FIG. 2A is a vertical side view of the base, FIG. 2B is a schematic perspective view of the nozzle, and FIG. 2C is a direction C of FIG. 2A. FIG. 2D is a schematic diagram of the nozzle hole viewed from directly below. FIGS. 3A and 3B are diagrams for explaining a swirl chamber combustion chamber of the diesel engine according to the first embodiment of the present invention, FIG. 3A is a cross-sectional plan view of a cylinder in which a piston is fitted, and FIG. 3B is a swirl chamber combustion. It is a vertical side view of a chamber and its peripheral part. FIG. 4 is a graph in which the exhaust gas characteristics of the vortex chamber type combustion chamber of FIG. 3 are compared with a comparative example having no auxiliary communication hole, in which the amount of nitrogen oxide generated against the load is plotted. FIG. 4 is a graph comparing the exhaust gas characteristics of the vortex chamber type combustion chamber of FIG. 3 with a comparative example, in which the generation amount of nitrogen oxide and the generation amount of smoke at a predetermined load are plotted. FIG. 6A is a graph for explaining the relationship between the exhaust gas characteristics of the vortex chamber type combustion chamber of FIG. 3 and the passage cross-sectional area of the auxiliary communication hole, and FIG. FIG. 6B is a plot of the variation rate of the amount of smoke generated with respect to the passage cross-sectional area, and FIG. 6C is a plot of FIG. 6A and FIG. (B) is a plot of the total variation rate. FIG. 7A is a plan view, FIG. 7B is a cross-sectional view taken along line BB in FIG. 7A, and FIG. 7C is a diagram illustrating a base used in the second embodiment of the present invention. FIG. 7D is a bottom view, and is a cross-sectional view taken along the line DD of FIG. FIG. 8A is a plan view, FIG. 8B is a cross-sectional view taken along line BB in FIG. 8A, and FIG. 8C is a diagram illustrating a base used in the third embodiment of the present invention. A bottom view, FIG. 8 (D), is a cross-sectional view taken along the line DD of FIG. 8 (B). FIG. 9A is a plan view, FIG. 9B is a cross-sectional view taken along line BB in FIG. 9A, and FIG. 9C is a diagram illustrating a base used in the fourth embodiment of the present invention. A bottom view, FIG. 9D, is a cross-sectional view taken along the line DD of FIG. 9B. FIG. 10A is a plan view of a nozzle and a piston, and FIG. 10B is a longitudinal side view of a vortex chamber combustion chamber and its peripheral part, illustrating a vortex chamber combustion chamber of a diesel engine according to the prior art. It is.

Explanation of symbols

(1) ... Cylinder, (2) ... Piston, (3) ... Cylinder center axis, (4) ... Cylinder peripheral wall, (5) ... Cylinder head, (6) ... Recess, (6a) ... Recess, (7) ... (7a) ... depression, (7b) ... upper opening surface, (7c) ... center point, (7d) ... bottom of the die, (8) ... vortex chamber, (9) ... main combustion chamber, (10) ... mouthpiece Lower wall, (11) ... nozzle, (12) ... auxiliary communication hole, (12a) ... auxiliary communication hole central axis, (12b) ... extension chamber side extension line, (12c) ... center of upper opening, (13) ... (14) ... Spherical extension line, (15) ... Sphere, (16) ... Vertical reference line, (17) ... Main nozzle, (17a) ... Main nozzle center axis, (18) ... Aside Jet port, (18a) ... Axis center axis.

Claims (28)

With the top dead center direction of the piston (2) in the cylinder (1) up, the bottom dead center direction down, the cylinder center axis (3) side rear, the cylinder peripheral wall (4) side front,
Above the cylinder peripheral wall (4), an upward concave portion (6) is provided in the lower portion of the cylinder head (5), and a base (7) is fitted to the inlet of the concave portion (6) so The depression (6a) and the downward depression (7a) in the base (7) form a vortex chamber (8), the main combustion chamber (9) is formed in the cylinder (1), and the base lower wall (10) A nozzle hole (11) is provided on the rear side, and the nozzle hole (11) is inclined upwardly from the main combustion chamber (9) toward the vortex chamber (8), and the main combustion chamber (9) is inclined at the nozzle hole (11). Communicating with the vortex chamber (8)
The base lower wall (10) is provided with at least a pair of left and right auxiliary communication holes (12), (12), each auxiliary communication hole (12) is separated from the nozzle (11), and the base (7) is viewed from directly above. In this case, in the vortex chamber combustion chamber of the diesel engine, the auxiliary communication holes (12) are distributed so as to be on both sides of the nozzle center axis (13) or the vortex chamber extension line (14).
Assuming a sphere (15) centered on the center point (7c) of the upper opening surface (7b) of the recess (7a) of the base (7), the upper opening surface (7b) of the recess (7a) of the base (7) And the radius of the sphere (15) is 70%,
A diesel engine characterized in that each auxiliary communication hole (12) is oriented so that a vortex chamber side extension line (12b) of each auxiliary communication hole central axis (12a) passes through the sphere (15). A vortex chamber combustion chamber. In the vortex chamber combustion chamber of the diesel engine according to claim 1,
A vortex chamber combustion chamber for a diesel engine, wherein the radius of the sphere (15) is 60% instead of 70%. In the vortex chamber combustion chamber of the diesel engine according to claim 1,
A vortex chamber combustion chamber of a diesel engine, wherein the radius of the sphere (15) is 50% instead of 70%. In the vortex chamber combustion chamber of the diesel engine according to any one of claims 1 to 3,
When the base (7) is viewed from directly above, each auxiliary communication hole (12) is arranged such that the center (12c) of the upper opening of each auxiliary communication hole (12) overlaps the sphere (15) having a radius of 50%. A vortex chamber combustion chamber of a diesel engine, characterized by being arranged. In the vortex chamber combustion chamber of the diesel engine according to any one of claims 1 to 4,
Assuming a pair of left and right vertical reference lines (16) and (16) extending directly above the center (12c) of the upper opening of the pair of left and right auxiliary communication holes (12) and (12),
When the mouthpiece (7) is viewed from the side in a direction perpendicular to the nozzle center axis (13), the vortex chamber side extension line (12b) of each auxiliary communication hole center axis (12a) is connected to each vertical reference line (16 ), Each auxiliary communication hole (12) is oriented so as to overlap each other or to form an angle of 30 ° or less with each vertical reference line (16). Combustion chamber. In the vortex chamber combustion chamber of the diesel engine according to any one of claims 1 to 5,
Assuming a pair of left and right vertical reference lines (16) and (16) extending directly above the center (12c) of the upper opening of the pair of left and right auxiliary communication holes (12) and (12),
When the base (7) is viewed from directly behind the nozzle hole (11), the vortex chamber side extension line (12b) of each auxiliary communication hole central axis (12a) is connected to each vertical reference line (16). Each of the auxiliary communication holes (12) is oriented so as to overlap each other or to form an angle of 15 ° or less with each vertical reference line (16). Combustion chamber. In the vortex chamber type combustion chamber of the diesel engine according to any one of claims 1 to 6,
A diesel engine characterized in that the minimum passage cross-sectional area of the nozzle hole (11) is 100%, and the total of the minimum passage cross-sectional areas of the pair of auxiliary communication holes (12) and (12) is set to 3 to 15%. Nozzle chamber combustion chamber. In the vortex chamber combustion chamber of the diesel engine according to claim 7,
A diesel engine characterized in that, instead of setting the total of the minimum passage sectional areas of the pair of auxiliary communication holes (12) and (12) to 3 to 15%, this is set to 4 to 10%. Nozzle chamber combustion chamber. In the vortex chamber combustion chamber of the diesel engine according to any one of claims 1 to 8,
The nozzle hole (11) is composed of a main nozzle hole (17) and a pair of left and right side nozzle holes (18), (18), and each side nozzle hole (18) communicates with the main nozzle hole (17) on the peripheral side of the main nozzle hole (17). A vortex chamber combustion chamber of a diesel engine characterized by In the vortex chamber combustion chamber of the diesel engine according to claim 9,
When the mouthpiece (7) is viewed from the side in a direction perpendicular to the main nozzle center axis (17a), each side nozzle center axis (18a) is located behind the main nozzle center axis (17a). A vortex chamber combustion chamber of a diesel engine, characterized in that a nozzle (18) is arranged. In the vortex chamber combustion chamber of the diesel engine according to claim 10,
When the base (7) is viewed from the side in a direction orthogonal to the main nozzle center axis (17a), the elevation angle of each side nozzle center axis (18a) with respect to the base lower surface (7d) is the angle of the main nozzle center axis (17a). A vortex chamber type combustion chamber of a diesel engine, characterized in that each side nozzle hole (18) is oriented so as to be smaller than an elevation angle. In the vortex chamber combustion chamber of the diesel engine according to claim 11,
A diesel engine characterized in that each side nozzle hole (18) is oriented so that the distance between the pair of left and right side nozzle center axes (18a) and (18a) gradually decreases toward the front. A vortex chamber combustion chamber. In the vortex chamber combustion chamber of the diesel engine according to any one of claims 9 to 12,
A vortex chamber type combustion chamber of a diesel engine, characterized in that the passage cross-sectional area of each side nozzle (18) gradually decreases as it goes forward. In the vortex chamber combustion chamber of the diesel engine according to any one of claims 9 to 13,
When the base (7) is viewed from directly above, the side nozzles (18) are positioned at positions where the auxiliary nozzles (12) are retracted from the upper openings of the auxiliary communication holes (12) directly behind the central axis of the main nozzle (13). A vortex chamber type combustion chamber of a diesel engine, characterized in that each side nozzle hole (18) is disposed in the vortex chamber. In the vortex chamber combustion chamber of the diesel engine according to claim 1,
Assuming a pair of left and right vertical reference lines (16) and (16) extending directly above the center (12c) of the upper opening of the pair of left and right auxiliary communication holes (12) and (12),
When the mouthpiece (7) is viewed from the side in a direction perpendicular to the nozzle center axis (13), the vortex chamber side extension line (12b) of each auxiliary communication hole center axis (12a) is connected to each vertical reference line (16 Each auxiliary communication hole (12) so as to overlap each other or to form an angle of 30 ° or less with each vertical reference line (16),
When the base (7) is viewed from directly behind the nozzle hole (11), the vortex chamber side extension line (12b) of each auxiliary communication hole central axis (12a) is connected to each vertical reference line (16). Each of the auxiliary communication holes (12) is oriented so as to overlap each other or to form an angle of 15 ° or less with each vertical reference line (16). Combustion chamber. In the vortex chamber combustion chamber of the diesel engine according to claim 15,
A diesel engine characterized in that the minimum passage cross-sectional area of the nozzle hole (11) is 100%, and the total of the minimum passage cross-sectional areas of the pair of auxiliary communication holes (12) and (12) is set to 3 to 15%. Nozzle chamber combustion chamber. In the vortex chamber combustion chamber of the diesel engine according to claim 15 or 16,
The nozzle hole (11) is composed of a main nozzle hole (17) and a pair of left and right side nozzle holes (18), (18), and each side nozzle hole (18) communicates with the main nozzle hole (17) on the peripheral side of the main nozzle hole (17). A vortex chamber combustion chamber of a diesel engine characterized by In the vortex chamber combustion chamber of the diesel engine according to claim 17,
When the base (7) is viewed from directly above, the side nozzles (18) are positioned at positions where the auxiliary nozzles (12) are retracted from the upper openings of the auxiliary communication holes (12) directly behind the central axis of the main nozzle (13). A vortex chamber type combustion chamber of a diesel engine, characterized in that each side nozzle hole (18) is disposed in the vortex chamber. In the vortex chamber combustion chamber of the diesel engine according to claim 1,
Each auxiliary communication hole so that each auxiliary communication hole central axis (12a) rises vertically from the lower surface (7d) of the base when the base (7) is viewed from the side in a direction orthogonal to the nozzle center axis (13). A vortex chamber combustion chamber of a diesel engine, characterized by directing (12). In the vortex chamber combustion chamber of the diesel engine according to claim 1,
When the base (7) is viewed from directly behind the nozzle hole (11), the auxiliary communication holes (so that each auxiliary communication hole central axis (12a) rises vertically from the base lower surface (7d). 12) A vortex chamber combustion chamber of a diesel engine characterized by being directed. In the vortex chamber combustion chamber of the diesel engine according to claim 1,
Each auxiliary communication hole so that each auxiliary communication hole central axis (12a) rises vertically from the lower surface (7d) of the base when the base (7) is viewed from the side in a direction orthogonal to the nozzle center axis (13). Orient (12) and
When the base (7) is viewed from directly behind the nozzle hole (11), the auxiliary communication holes (so that each auxiliary communication hole central axis (12a) rises vertically from the base lower surface (7d). 12) A vortex chamber combustion chamber of a diesel engine characterized by being directed. In the vortex chamber combustion chamber of the diesel engine according to claim 21,
A diesel engine characterized in that the minimum passage cross-sectional area of the nozzle hole (11) is 100%, and the total of the minimum passage cross-sectional areas of the pair of auxiliary communication holes (12) and (12) is set to 3 to 15%. Nozzle chamber combustion chamber. In the vortex chamber combustion chamber of the diesel engine according to claim 21 or claim 22,
The nozzle hole (11) is composed of a main nozzle hole (17) and a pair of left and right side nozzle holes (18), (18), and each side nozzle hole (18) communicates with the main nozzle hole (17) on the peripheral side of the main nozzle hole (17). A vortex chamber combustion chamber of a diesel engine characterized by In the vortex chamber combustion chamber of the diesel engine according to claim 23,
When the base (7) is viewed from directly above, the side nozzles (18) are positioned at positions where the auxiliary nozzles (12) are retracted from the upper openings of the auxiliary communication holes (12) directly behind the central axis of the main nozzle (13). A vortex chamber type combustion chamber of a diesel engine, characterized in that each side nozzle hole (18) is disposed in the vortex chamber. In the vortex chamber combustion chamber of the diesel engine according to any one of claims 1 to 18,
A vortex chamber combustion chamber for a diesel engine, wherein a pair of left and right auxiliary communication holes (12), (12) are inclined upwardly from the main combustion chamber (9) toward the vortex chamber (8). In the vortex chamber combustion chamber of the diesel engine according to any one of claims 1 to 18,
A vortex chamber combustion chamber of a diesel engine, wherein a pair of left and right auxiliary communication holes (12), (12) are inclined upward and backward from the main combustion chamber (9) toward the vortex chamber (8). In the vortex chamber combustion chamber of the diesel engine according to any one of claims 1 to 18,
When the base (7) is viewed from directly behind the nozzle hole (11), the distance between the pair of left and right auxiliary communication holes (12) and (12) gradually decreases as it goes upward. A vortex chamber type combustion chamber of a diesel engine, characterized in that each auxiliary communication hole (12) is oriented in the direction. In the vortex chamber combustion chamber of the diesel engine according to any one of claims 1 to 18,
When the base (7) is viewed from directly behind the nozzle hole (11), the distance between the pair of left and right auxiliary communication holes (12) and (12) gradually increases as it goes upward. A vortex chamber type combustion chamber of a diesel engine, characterized in that each auxiliary communication hole (12) is oriented in the direction.

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