JP2000130170A - Combustion chamber in direct injection diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a combustion chamber in which both of upward and downward spray are easy to be diffused and are difficult to be mixed, to improve fuel consumption and to reduce generated black smoke by forming a step of a difference in level shape between a side wall of the combustion chamber that upward spray reaches and a bottom surface of the combustion chamber that downward spray reaches. SOLUTION: In a combustion chamber 3, upward spray 6 injected from an upper nozzle hole 1a is diffused along a side wall 3a after upward spray 6 collides against the side wall 3a, and downward spray injected from a lower nozzle hole 1b is diffused along a bottom surface 3b after downward spray 7 collides against the bottom surface 3b. Upward spray 6 is diffused in space within the combustion chamber 3 by changing a diffusing direction in a step 5 of a difference in level and also downward spray 7 is diffused in space within the combustion chamber 3 in the same way. As a result, overlapping of both of sprays 6, 7 each other is prevented and a diffusion state is improved. A projection part 4 is formed at the center part of the bottom surface 3b and also overlapping of downward spray 7 each other diffused to the inside of the bottom surface 3b is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion chamber of a direct injection type diesel engine in which injection nozzles having upward spray nozzles and downward spray nozzles are provided in a staggered manner. The present invention relates to a combustion chamber of a direct injection diesel engine which is configured to be easily mixed and difficult to mix upward spray and downward spray.

[0002]

2. Description of the Related Art Conventionally, an injection nozzle has been disposed inside a combustion chamber formed at the head of a piston, and the spray collides with the wall surface of the combustion chamber to perform collision diffusion combustion by positively utilizing the air flow such as swirl and squish. A combustion chamber of a direct injection diesel engine configured as described above is known. For example, Japanese Utility Model Application Laid-Open No. 56-133925 and Japanese Patent Application Laid-Open No. 3-117672.
No. In such a combustion chamber, the injection port of the injection nozzle is centered on the nozzle axis in order to diffuse fuel over a wide range, improve air use efficiency, improve fuel efficiency and reduce exhaust black smoke concentration. Arranged radially, the nozzles are arranged in a staggered manner in two upper and lower stages, so that not only the outer peripheral part of the combustion chamber but also the vicinity of the center of the combustion chamber where fuel is relatively difficult to reach is used. was there. For example, as shown in FIGS. 12 and 13, in the injection nozzle 51, a plurality of upper nozzles 51a for spraying substantially to the side and a plurality of lower nozzles 51b for spraying obliquely downward are arranged in a staggered manner. The upward spray 61 is injected from the upper injection port 51a toward the side wall 52a of the combustion chamber 52 formed at the center of the upper surface of the piston 50, and the downward spray 62 is formed from the lower injection port 51b into the combustion chamber 52. It is configured to be sprayed toward the bottom surface 52b.

[0003]

However, in the combustion chamber 52 as described above, the downward spray 62 from the lower injection port 51b flows along the bottom surface 52b of the combustion chamber 52 and diffuses to reach the side wall 52a. Upper nozzle 51a
Upward spray 61 flows along the side wall 52a and diffuses to reach the bottom surface 52b.
Downward spray 62 and upward spray 61 from the upper injection port 51a are mixed and overlapped, and combustion in this portion is deteriorated, that is, black smoke is increased, and the diffusion of the upper and lower sprays is prevented. I was In view of the above, the present invention provides a combustion chamber in which the spray from the upper nozzle and the lower spray is easily diffused, and in which the upward spray and the downward spray are difficult to mix, thereby improving fuel efficiency and reducing black smoke generated. It is.

[0004]

The present invention uses the following means in order to solve the above problems. That is, in claim 1, an injection nozzle which injects a group of upward sprays toward the combustion chamber side wall and a nozzle which staggers a group of downward sprays toward the bottom of the combustion chamber is provided inside. In the arranged combustion chamber, a step-shaped step was formed between the combustion chamber side wall where the upward spray reaches and the combustion chamber bottom where the downward spray reaches.

According to a second aspect of the present invention, an injection nozzle for injecting a group of upward sprays toward the side wall of the combustion chamber and a nozzle for injecting a group of downward sprays toward the bottom of the combustion chamber are provided in a staggered manner. In the combustion chamber where the
A step was formed between the side wall of the combustion chamber where the upward spray reached and the bottom of the combustion chamber where the downward spray reached, and at least the bottom of the combustion chamber was formed substantially flat.

According to a third aspect of the present invention, an injection nozzle for injecting a group of upward sprays toward the side wall of the combustion chamber and an injection nozzle for injecting a group of downward sprays toward the bottom of the combustion chamber are provided in a staggered manner. In the combustion chamber where the
A step was formed between the side wall of the combustion chamber where the upward spray reached and the bottom of the combustion chamber where the downward spray reached, and at least the side wall of the combustion chamber was formed in a substantially cylindrical or tapered shape.

According to a fourth aspect of the present invention, an injection nozzle for injecting a group of upward sprays toward the combustion chamber side wall and an injection nozzle for injecting a group of downward sprays toward the bottom of the combustion chamber are provided in a staggered manner. In the combustion chamber where the
A step is formed between the side wall of the combustion chamber where the upward spray reaches and the bottom of the combustion chamber where the downward spray reaches. At least the height from the bottom of the combustion chamber to the step is h, and the depth of the combustion chamber is H. In this case, the relationship h / H <0.5 was satisfied.

According to a fifth aspect of the present invention, an injection nozzle for injecting a group of upward sprays toward the side wall of the combustion chamber and a nozzle for injecting a group of downward sprays toward the bottom of the combustion chamber are provided in a staggered manner. In the combustion chamber where the
A step was formed between the combustion chamber side wall to which the upward spray reached and the combustion chamber bottom surface to which the downward spray reached, and at least the step and the combustion chamber side wall were connected by an arc in a side view.

According to a sixth aspect of the present invention, there is provided an injection nozzle in which a group of upward sprays is sprayed toward a side wall of the combustion chamber, and a group of downward sprays are formed in a staggered manner. In the combustion chamber where the
A step is formed between the combustion chamber side wall where the upward spray reaches and the combustion chamber bottom where the downward spray reaches, and at least the spray direction of the downward spray and the spray direction of the upper spray disposed on both sides of the downward spray. The center between them was shifted within the range of 0 ° to 20 ° to the swirl upstream side in plan view.

According to a seventh aspect of the present invention, there is provided an injection nozzle in which a group of upward sprays is sprayed toward a side wall of the combustion chamber, and a group of downward sprays is formed in a staggered manner. In the combustion chamber where the
A step was formed between the side wall of the combustion chamber where the upward spray reached and the bottom of the combustion chamber where the downward spray reached, and the step was arranged only at a position facing the injection direction of the downward spray.

According to the present invention, an injection nozzle for injecting a group of upward sprays toward the side wall of the combustion chamber and an injection nozzle for injecting a group of downward sprays toward the bottom of the combustion chamber are provided in a staggered manner. In the combustion chamber where the
A step is formed between the combustion chamber side wall to which the upward spray reaches and the combustion chamber bottom surface to which the downward spray reaches, and in a plan view, a portion opposed to the injection direction of the downward spray in the step is perpendicular to the injection direction. The surface was formed in a shape inclined toward the outer peripheral direction toward the swirl upstream side.

According to a ninth aspect of the present invention, there is provided an injection nozzle in which a group of upward sprays is sprayed toward a side wall of a combustion chamber, and a group of downward sprays are formed in a staggered manner. In the combustion chamber where the
A step was formed between the side wall of the combustion chamber where the upward spray reached and the bottom of the combustion chamber where the downward spray reached, and substantially circular concave portions were formed on both sides of the portion where the downward spray reached the bottom of the combustion chamber.

According to a tenth aspect of the present invention, an injection nozzle for injecting a group of upward sprays toward the side wall of the combustion chamber and an injection nozzle for injecting a group of downward spray toward the bottom of the combustion chamber are provided in a staggered manner. In the combustion chamber in which the downward spray is formed, a step is formed between the combustion chamber side wall where the upward spray reaches and the swirl downstream of the portion where the downward spray reaches the combustion chamber bottom where the downward spray reaches. A substantially circular recess was formed on the side.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The problems and means to be solved by the present invention are as described above. Next, an embodiment of the present invention shown in the attached drawings will be described. FIG. 1 is a side sectional view showing a combustion chamber of the present invention in which a substantially conical projection is projected upward at the center, FIG. 2 is a plan view of the same, and FIG. 3 is a second embodiment of the combustion chamber. FIG. 4 is a plan view showing a third embodiment of the combustion chamber, FIG. 5 is a side sectional view of the same, FIG. 6 is a plan view showing a fourth embodiment of the combustion chamber, and FIG. FIG. 8
Is a plan view showing a fifth embodiment of the combustion chamber, FIG. 9 is a side sectional view of the same, FIG. 10 is a plan view showing a sixth embodiment of the combustion chamber, FIG. 11 is a side sectional view of the same, and FIG. And FIG. 13 is a side sectional view of the same.

The structure of the combustion chamber of the direct injection diesel engine of the present invention will be described with reference to FIGS. Piston 2
A combustion chamber 3 having a substantially cylindrical deep dish shape that is horizontally long in a side view and circular in a plan view is formed at the center of the upper surface of the combustion chamber 3. An injection nozzle 1 is disposed above the combustion chamber 3, and the lower end thereof faces the inside of the combustion chamber 3. At the lower end of the injection nozzle 1 facing the inside of the combustion chamber 3, two rows of upper and lower nozzles, that is, a plurality of upper nozzles 1a.
1a... And a plurality of lower injection ports 1b.

The upper orifices 1a, 1a... And the lower orifices 1b, 1b... Are arranged at substantially equal intervals around the axis of the injection nozzle 1, and are arranged vertically in a staggered manner. I have. Also, for example, an upper nozzle 1 forming an upper group of nozzles
The numbers of a, 1a,.
.. are twice as many as the number of b · 1b.

The spray from the upper nozzles 1a, ie, upward spray 6, is sprayed toward the side wall 3a of the combustion chamber 3 and reaches the side wall 3a.
The sprays from b, 1b,..., that is, downward sprays 7 are configured to be injected toward the bottom surface 3b of the combustion chamber 3 and reach the bottom surface 3b. Then, in plan view, for example, the direction of the center between the spraying directions of the upward sprays 6 from the upper spray ports 1a is defined as the spray direction of the spray 7 from the lower spray port 1b.

In the case where a substantially conical projection 4 projects upward from the center of the bottom surface 3b of the combustion chamber 3, the space between the bottom surface 3b and the side wall 3a extends over the entire circumference. Combustion chamber 3
A step 5 having a step-like shape protruding inward is formed.
The bottom 3b of the combustion chamber 3 is formed in a substantially planar shape except for the portion where the projection 4 is formed, and the side wall 3a is formed in a substantially cylindrical or tapered shape.

In the combustion chamber 3, the depth of the combustion chamber is set to H.
Assuming that the height from the bottom surface 3b to the step 5 is h, the depth H of the combustion chamber is set so that the following equation (1) holds.
And the height h of step 5. h / H <0.5- (1)

Further, the space between the side wall 3a of the combustion chamber 3 and the step 5 is formed in an arc 8 shape in a side view.
The arc 8 is formed as an arc having a relatively large radius. Similarly, the space between the bottom surface 3b of the combustion chamber 3 and the step 5 is formed in an arc shape in a side view.

In the combustion chamber 3 configured as described above,
Upward spray 6 injected from upper nozzles 1a
.. Collides with the side wall 3a and then diffuses along the side wall 3a, and after the downward sprays 7.7 sprayed from the lower nozzles 1b 1b collide with the bottom surface 3b. , Diffuses along the bottom surface 3b. In this case, the side wall 3a
, Which are spread downward, are changed in the direction of diffusion by the step 5 of the step shape, are diffused in the space in the combustion chamber 3, and are diffused in the outer circumferential direction of the bottom surface 3b. Are also diffused into the space in the combustion chamber 3, so that the upward sprays 6, 6 ... and the downward sprays 7, 7 ... can be prevented from overlapping each other. At the same time, the diffusion state can be improved.

Further, since the projections 4 are formed at the center of the bottom surface 3b, it is possible to prevent the downward sprays 7, 7,... . This makes it possible to improve the diffusion state of the sprays 6, 6,... And the sprays 7, 7,. Generated black smoke can be reduced.

Also, since the side wall 3a of the combustion chamber 3 against which the upward sprays 6, 6... Collide is formed in a substantially cylindrical or tapered shape, the upward sprays 6, 6,. Since the bottom surface 3b of the combustion chamber 3 against which the downward sprays 7, 7... Collide is formed in a substantially flat surface, the downward sprays 7, 7. .. And the downward sprays 7, 7,... Can be improved, and the air use efficiency in the combustion chamber 3 can be increased to improve fuel efficiency. ing.

[0024] Further, by configuring the depth H of the combustion chamber and the height h of the step 5 so as to satisfy the relationship of h / H <0.5, the upward sprays 6, 6... The spray reaches the side wall 3a of the combustion chamber 3 and is sprayed downward.
.. Reach the bottom surface 3b without fail, and the diffusion state can be improved. Furthermore, as described above, by forming a relatively large arc 8 shape between the side wall 3a of the combustion chamber 3 and the step 5 in a side view, the upward spray 6.6 colliding with the side wall 3a is formed. The diffusion in the step 5 direction is smoothly performed, and the diffusion state can be improved.

The downward sprays 7, 7,... From the lower nozzles 1b, 1b,. That is, as shown in FIG. 3, the swirl direction in the combustion chamber 3 is configured to be clockwise in a plan view, and the injection direction of the downward sprays 7, 7. In this case, the spray is shifted from the center of the upward sprays 6, 6 by a certain angle α toward the upstream side of the swirl. And the angle α is
The value is in the range of 0 ° to 20 °.

As described above, the injection direction of the downward sprays 7, 7... From the center direction between the upward spray directions of the upward sprays 6, 6.
By shifting by an angle α within the range of °,
The swirl effect between the upward sprays 6, 6,... And the downward sprays 7, 7,... Is considered, and the upward sprays 6, 6,. It is possible to further reduce the overlap and further improve the diffusion state of the spray.

Step 5 can also be configured as follows. That is, the step 5 is not formed over the entire circumference of the combustion chamber 3 but is disposed only at a position facing the injection direction of the downward spray 7, 7,... As in step 15 shown in FIGS. You can do it. The step 15 disposed at a position opposite to the ejection direction of the downward sprays 7 extends in the plan view to the injection direction of the upward sprays 6 disposed on both sides of the downward spray 7. Both ends 15a of the step 15 are inclined outward.

As described above, the step 15 is performed with the downward spray 7
7 are arranged only at the position opposite to the injection direction, so that the upward spray 6.6 diffuses along the side wall 3a of the combustion chamber 3 and then the downward spray 7.7 is not injected. Of the upward spray 6.6 can be further improved.

Step 5 may be configured as follows. That is, instead of forming a circular shape as in step 5, as shown in step 25 shown in FIGS.
Is formed on an inclined surface 25a having a shape in which a vertical surface 25a 'with respect to the injection direction is inclined toward the upstream side of the swirl by a certain angle β toward the outer peripheral direction.

As described above, the downward spray 7 in step 25 is performed.
The part facing the injection direction of 7...
Are spread along the swirl flow, and diffuse downward along the inclined surface 25a, and spread upward along the side wall 3a of the combustion chamber 3. .. Can be further prevented from overlapping.

Further, the combustion chamber 3 can be constructed as follows. That is, as in the combustion chamber 3 shown in FIGS. 8 and 9, the substantially circular concave portions 9.9 are formed on both sides of the portion where the downward spray 7 reaches the bottom surface 3b. And
The recesses 9 are arranged so as to slightly overlap with the portion where the downward spray 7 reaches. By forming the recesses 9 in the bottom surface 3b of the combustion chamber 3, the downward spray 7 reaching the bottom surface 3b is
Since the downward spray 7 is diffused toward the concave portions 9 located at a lower position, the downward spray 7 is easily diffused, and the state of diffusion can be improved.

Further, the combustion chamber 3 can be configured as follows. That is, the combustion chamber 3 shown in FIGS.
As described above, the recess 9 is formed in the swirl downstream portion of the portion where the downward spray 7 of the bottom surface 3b reaches. And
The concave portion 9 is arranged so as to slightly overlap with the portion where the downward spray 7 reaches. By forming the recesses 9 in the bottom surface 3b of the combustion chamber 3 in this manner, the downward spray 7 that reaches the bottom surface 3b by the swirl flow and spreads is positioned lower than the bottom surface 3b. Since the downward spray 7 is diffused toward the concave portion 9 located, the downward spray 7 is easily diffused, and the state of diffusion can be improved.

[0033]

According to the present invention, the following effects can be obtained by the configuration described above. That is, as described in claim 1, a step-shaped step is formed between the combustion chamber side wall to which the upward spray reaches and the combustion chamber bottom to which the downward spray reaches, so that the upward spray diffusing below the side wall is reduced. The direction of diffusion is changed by the step and diffuses into the space inside the combustion chamber, and the downward spray that diffuses toward the outer periphery of the bottom surface also diffuses into the space inside the combustion chamber, so that the upward spray and the downward spray are mutually separated. Overlap can be prevented and the diffusion state can be improved. As a result, it is possible to reduce the generated black smoke, and to improve the fuel efficiency by increasing the air use efficiency in the combustion chamber.

Further, since at least the bottom surface of the combustion chamber is formed to be substantially flat, the downward spray can be easily diffused, the diffusion state can be improved, and the air use efficiency in the combustion chamber can be improved. It is possible to improve fuel efficiency.

Further, since at least the side wall of the combustion chamber is formed in a substantially cylindrical shape or a tapered shape, the upward spray can be easily diffused and the diffusion state can be improved, and the air in the combustion chamber can be improved. It is possible to improve the fuel efficiency by increasing the use efficiency.

Further, when the height from the bottom of the combustion chamber to the step is h and the depth of the combustion chamber is H, the relationship h / H <0.5 is satisfied. As a result, the upward spray surely reaches the side wall of the combustion chamber, and the downward spray surely reaches the bottom of the combustion chamber, so that the diffusion state can be improved, and the air in the combustion chamber can be improved. It is possible to improve the fuel efficiency by increasing the use efficiency. In addition, it is possible to reliably prevent the upward spray and the downward spray from overlapping, thereby reducing black smoke generated.

Further, since the step and the side wall of the combustion chamber are connected by an arc in at least a side view, the gap between the side wall of the combustion chamber and the step can be further improved as described above. Is formed in an arc shape in a side view, so that the upward spray that collides with the side wall,
The diffusion in the step direction is performed smoothly, and the diffusion state can be improved. Thus, it is possible to improve the fuel efficiency by increasing the air use efficiency in the combustion chamber.

Further, as set forth in claim 6, at least the direction between the spraying direction of the downward spray and the center between the spraying directions of the upper sprays disposed on both sides of the downward spray is 0 ° toward the swirl upstream in plan view. Since the angle is shifted within the range of ２０20 °, the downward spray can be prevented from being overlapped in consideration of the swirl flow, and is easily diffused. Thus, it is possible to improve the fuel efficiency by increasing the air use efficiency in the combustion chamber.

Further, since the step is arranged only at a position opposed to the injection direction of the downward spray, the upward spray is diffused along the side wall of the combustion chamber, and then the upward spray is formed at a portion where the downward spray is not injected. Since it is diffused toward the bottom surface, the diffusion state of the upward spray can be further improved. As a result, it is possible to further increase the air use efficiency in the combustion chamber and improve the fuel efficiency.

Furthermore, in a plan view, the portion facing the spraying direction of the downward spray in the plan view has a shape in which a vertical surface with respect to the spraying direction is inclined toward the outer peripheral direction toward the swirl upstream side. Therefore, the downward spray that spreads along with the swirl flow is diffused along the inclined surface, and it is possible to prevent the downward spray that mixes with the upward spray that diffuses along the side wall of the combustion chamber from overlapping. In addition, the diffusion state of the downward spray can be improved. As a result, it is possible to reduce the generated black smoke, and to improve the fuel efficiency by increasing the air use efficiency in the combustion chamber.

Further, since substantially circular concave portions are formed on both sides of a portion where the downward spray reaches the bottom of the combustion chamber, the downward spray reaching the bottom of the combustion chamber is formed as follows.
Since the downward spray is diffused toward the concave portion located at a position lower than the bottom surface, the downward spray is easily diffused, and the diffusion state can be improved. Thus, it is possible to improve the fuel efficiency by increasing the air use efficiency in the combustion chamber.

Further, since a substantially circular concave portion is formed on the swirl downstream side of the portion where the downward spray reaches the bottom of the combustion chamber, the swirl downstream on the swirl downstream relatively easily overlaps with the upward spray. Since the spray is to be diffused toward the concave portion located lower than the bottom surface,
The downward spray is easily diffused, and the state of diffusion can be improved. Thus, it is possible to improve the fuel efficiency by increasing the air use efficiency in the combustion chamber.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a case where a substantially conical projection is projected upward at the center of a combustion chamber of the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a plan view showing a second embodiment of the combustion chamber.

FIG. 4 is a plan view showing a third embodiment of the combustion chamber.

FIG. 5 is a side sectional view of the same.

FIG. 6 is a plan view showing a fourth embodiment of the combustion chamber.

FIG. 7 is a side sectional view of the same.

FIG. 8 is a plan view showing a fifth embodiment of the combustion chamber.

FIG. 9 is a side sectional view of the same.

FIG. 10 is a plan view showing a sixth embodiment of the combustion chamber.

FIG. 11 is a side sectional view of the same.

FIG. 12 is a plan view showing a conventional combustion chamber.

FIG. 13 is a side sectional view of the same.

[Explanation of symbols]

 h Height (from bottom of combustion chamber to step) H Depth of combustion chamber 1 Injection nozzle 1a Upper nozzle 1b Lower nozzle 2 Piston 3 Combustion chamber 3a Side wall 3b Bottom surface 5 Step 6 Upward spray 7 Downward spray 8 Arc 9 Recess

Continuing from the front page (72) Inventor Shigeru Yoshikawa 1-32 Chaya-cho, Kita-ku, Osaka-shi, Osaka Inside Yanmar Diesel Co., Ltd. (72) Inventor Koji Masuda 1-32 Chaya-cho, Kita-ku, Osaka-shi, Osaka In-house F-term (reference) 3G023 AA02 AA04 AA07 AB05 AC05 AD02 AD06 AD09 AD14 3G066 AA07 AB02 AD12 BA02 BA17 BA24 CC14 CC28 CC34 CC48 CD28

Claims (10)

[Claims] 1. Combustion in which an injection nozzle which injects a group of upward sprays toward a side wall of a combustion chamber and a nozzle in which a group of downward sprays is injected in a staggered manner toward a bottom of the combustion chamber are arranged inside. In the chamber, between the combustion chamber side wall where the upward spray reaches and the bottom of the combustion chamber where the downward spray reaches
A combustion chamber for a direct-injection diesel engine, wherein stepped steps are formed. 2. Combustion in which an injection nozzle for injecting a group of upward sprays toward a combustion chamber side wall and an injection nozzle in which a group of downward sprays for injecting a group of downward sprays toward the bottom of the combustion chamber are arranged in a zigzag manner are arranged inside. A direct injection diesel engine, wherein a step is formed between a side wall of the combustion chamber to which the upward spray reaches and a bottom of the combustion chamber to which the downward spray reaches, and at least the bottom of the combustion chamber is formed substantially flat. Engine combustion chamber. 3. Combustion in which an injection nozzle for injecting a group of upward sprays toward the combustion chamber side wall and an injection nozzle in which a group of downward sprays for injecting a group of downward spray toward the bottom of the combustion chamber are provided in a zigzag manner are provided. In the chamber, a step is formed between the side wall of the combustion chamber where the upward spray reaches and the bottom of the combustion chamber where the downward spray reaches, and at least the side wall of the combustion chamber is formed in a substantially cylindrical shape or a tapered shape. Combustion chamber of a direct injection diesel engine. 4. Combustion in which an injection nozzle for injecting a group of upward sprays toward the combustion chamber side wall and an injection nozzle in which a group of downward sprays for injecting a group of downward spray toward the bottom of the combustion chamber are provided in a zigzag manner are provided. In the chamber, a step is formed between the side wall of the combustion chamber where the upward spray reaches and the bottom of the combustion chamber where the downward spray reaches, and at least the height from the bottom of the combustion chamber to the step is h, and the depth of the combustion chamber is Is H,
A combustion chamber for a direct injection diesel engine, characterized by satisfying a relationship of h / H <0.5. 5. Combustion in which an injection nozzle for injecting a group of upward sprays toward a side wall of a combustion chamber and an injection nozzle in which a group of downward sprays for injecting a group of downward spray toward a bottom of the combustion chamber are arranged in a zigzag manner. In the chamber, a step is formed between the combustion chamber side wall to which the upward spray reaches and the combustion chamber bottom to which the downward spray reaches, and at least the step and the combustion chamber side wall are connected by an arc in a side view. A combustion chamber for a direct injection diesel engine. 6. Combustion in which an injection nozzle for injecting a group of upward sprays toward a side wall of a combustion chamber and an injection nozzle in which a group of downward sprays for jetting a group of downward sprays toward a bottom surface of the combustion chamber are provided in a staggered manner are provided. In the chamber, a step is formed between the combustion chamber side wall where the upward spray reaches and the combustion chamber bottom where the downward spray reaches, and at least the spray direction of the downward spray and the upper spray disposed on both sides of the downward spray. 0 ° to the swirl upstream in plan view
A combustion chamber for a direct injection diesel engine, wherein the combustion chamber is shifted within a range of up to 20 degrees. 7. Combustion in which an injection nozzle for injecting a group of upward sprays toward the combustion chamber side wall and an injection nozzle in which a group of downward sprays for jetting a group of downward spray toward the bottom of the combustion chamber are provided in a zigzag manner are provided. In the chamber, a step is formed between the combustion chamber side wall to which the upward spray reaches and the combustion chamber bottom surface to which the downward spray reaches, and the step is arranged only at a position facing the injection direction of the downward spray. Combustion chamber of a direct injection diesel engine. 8. Combustion in which an injection nozzle for injecting a group of upward sprays toward the side wall of the combustion chamber and an injection nozzle for providing a group of downward sprays toward the bottom of the combustion chamber in a staggered manner are arranged inside. In the chamber, a step is formed between the combustion chamber side wall to which the upward spray reaches and the combustion chamber bottom surface to which the downward spray reaches, and in plan view, a part opposed to the injection direction of the downward spray in the step is the injection. A combustion chamber for a direct-injection diesel engine, wherein a vertical surface with respect to the direction is formed in a shape inclined toward an outer peripheral direction toward a swirl upstream side. 9. Combustion in which an injection nozzle having a staggered injection nozzle for injecting a group of upward sprays toward the combustion chamber side wall and an injection nozzle for injecting a group of downward sprays toward the bottom of the combustion chamber is provided therein. In the chamber, a step is formed between the combustion chamber side wall where the upward spray reaches and the combustion chamber bottom where the downward spray reaches, and substantially circular concave portions are formed on both sides of the portion where the downward spray reaches the combustion chamber bottom. A combustion chamber of a direct injection diesel engine characterized by being formed. 10. Combustion in which an injection nozzle for injecting a group of upward sprays toward the combustion chamber side wall and an injection nozzle in which a group of downward sprays for injecting a group of downward spray toward the bottom of the combustion chamber are provided in a zigzag manner are provided. In the chamber, a step is formed between the side wall of the combustion chamber where the upward spray reaches and the bottom of the combustion chamber where the downward spray reaches, and a substantially circular shape is formed on the swirl downstream side of the portion where the downward spray reaches the bottom of the combustion chamber. A combustion chamber for a direct injection diesel engine, characterized by forming a recess.