JP2002285850A - Direct injection type combustion chamber for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the sufficient volume of a swirl chamber 2 and prevent the occurrence of the insufficiency of air by prolonging the thickness 27 of a spray collision part 11 to increase the amount of spray fuel colliding against the spray collision part 11 and rebounding to the vicinity of a swirl chamber inlet 4 and increase an air use rate and by shortening the thickness 28 of a spray non-collision part 18 to prolong a height 29 from the inner bottom face 24 of the swirl chamber 4 to a ceiling wall 3 forming a spray non-collision part 20. SOLUTION: In a direct injection type combustion chamber for a diesel engine constituted such that a plurality of fuel sprayings 6 are radially performed from a multihole injection nozzle 5 to collide spray fuel against the inner peripheral face 7 of the swirl chamber inlet 4, the thickness 27 of each spray collision part 11 on the inner peripheral face 7 of the swirl chamber inlet 4 is set to be longer than thickness 28 of the spray non-collision part 20 positioned between adjacent spray collision parts 11 and 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art FIG. 3 shows a conventional direct injection combustion chamber of a diesel engine. This has the following configuration, similarly to the present invention. As shown in FIG. 3B, a swirl chamber (102) is provided in the piston head (101), and a swirl chamber inlet (104) is opened in a ceiling wall (103) of the swirl chamber (102). As shown in 3 (A),
Multiple fuel sprays radially from the multi-hole injection nozzle (105)
(106) is performed, and the spray fuel is supplied to the swirl chamber entrance (10
It is configured to collide with the inner peripheral surface (107) of 4). In addition, the code | symbol (108) in FIG.
(109) is a spray center point, (110) is a swirl chamber (102)
(118) is a swirl air flow, and (124) is an inner bottom surface of the swirl chamber (102). However, this prior art differs from the present invention in the following points. As shown in FIG. 3 (B), the thickness of the inner peripheral surface (107) of the swirl chamber entrance (104) is constant, and the thickness of each spray impingement section (111).
(127) and the thickness dimension (128) of each spray non-collision part (120) located between the adjacent spray collision parts (111) and (111).
And have the same length.

[0003]

The above prior art has the following problems. << 1 >> The concentration of unburned harmful components in the exhaust gas is high, and the smoke emission concentration is also high. In order to increase the volume of the swirl chamber (102), if the overall thickness of the swirl chamber inlet (104) is reduced, the thickness (127) of the spray impingement section (111) is reduced.
Therefore, the amount of the spray fuel that collides with the spray collision portion (111) and rebounds near the swirl chamber entrance (104) decreases. Therefore, the spray fuel does not sufficiently mix with the air near the swirl chamber inlet (104), and the air utilization rate decreases. Further, the spray fuel easily enters the squish space (119). Since the squish space (119) has a large heat radiation area per internal volume, proper combustion is not performed here, and much of the fuel that has entered here is likely to be discharged without being burned. For this reason, the concentration of the unburned harmful components in the exhaust gas is high, and the exhaust gas concentration is also high. On the other hand, the spray collision part
If the thickness dimension (127) of (111) is increased, the overall thickness dimension of the swirl chamber entrance (104) is increased, so that the distance from the inner bottom surface (124) of the swirl chamber (104) to the ceiling wall (103) is increased. The height dimension (129) is shortened, and the volume of the swirl chamber (102) cannot be sufficiently secured, and air shortage tends to occur. For this reason, the concentration of the unburned harmful components in the exhaust gas is high, and the smoke exhaust concentration is also high.

<< 2 >> Output is limited. Since the concentration of the unburned harmful components in the exhaust gas is high and the concentration of the exhaust gas is also high, the fuel injection amount is limited and the output is limited.

An object of the present invention is to provide a direct injection combustion chamber of a diesel engine which can solve the above problems.

[0006]

Means for Solving the Problems (Invention of Claim 1) FIG.
As shown in (B), a swirl chamber is provided in the piston head (1).
(2) is installed, and a swirl chamber entrance (4) is opened in the ceiling wall (3) of the swirl chamber (2). As shown in FIG. In a direct injection combustion chamber of a diesel engine configured to perform a plurality of fuel sprays (6) and cause the sprayed fuel to collide with the inner peripheral surface (7) of the swirl chamber inlet (4), FIG. As shown in the figure, the thickness dimension (27) of each spray impingement section (11) on the inner peripheral surface (7) of the swirl chamber entrance (4) is positioned between the adjacent spray impingement sections (11) and (11). A direct injection combustion chamber for a diesel engine, characterized in that the thickness is longer than the thickness dimension (28) of the spray non-collision portion (20).

(Invention of claim 2) In the direct injection combustion chamber of the diesel engine according to claim 1, FIG.
As shown in the figure, the inner surface of the ceiling wall (3) of the swirl room (2)
The swirl chamber inlet (4) is formed in a tapered shape having an inner diameter gradually reduced toward the swirl chamber inlet (4), and viewed in a direction parallel to the cylinder center axis (8) as shown in FIG. 4
It is formed in a polygonal shape having more than two sides (16), and the interior angle (17) between each adjacent side (16) (16) is obtuse or right angle, and each adjacent side (16) (16) A direct injection combustion chamber for a diesel engine, characterized in that a bent portion between the two is defined as a spray collision portion (11).

[0008]

Operation and Effect of the Invention (Invention of claim 1) The invention of claim 1 has the following operation and effects. << 1 >> It is possible to reduce the concentration of unburned harmful components and exhaust gas concentration in exhaust gas. Thickness dimension of spray collision part (11)
By increasing the length of (27), it is possible to increase the amount of spray fuel that collides with the spray collision portion (11) and rebounds near the swirl chamber entrance (4). For this reason, the spray fuel can be sufficiently mixed with the air near the swirl chamber inlet (4), and the air utilization rate can be increased. Further, in this case, the spray fuel is less likely to enter the squish space (19), and the spray fuel is supplied to the swirl chamber.
(2) It is possible to burn properly. In addition, by shortening the thickness dimension (28) of the spray non-collision part (18), from the inner bottom surface (24) of the swirl chamber (4) to the ceiling wall (3) forming the spray non-collision part (20). Height dimension (29) can be lengthened. For this reason, the volume of the swirl chamber (2) can be sufficiently secured, and air shortage hardly occurs. For these reasons, it is possible to reduce the concentration of unburned harmful components and the concentration of flue gas in exhaust gas.

<< 2 >> The output can be increased. Since the concentration of unburned harmful components and exhaust gas concentration in exhaust gas can be reduced, the fuel injection amount can be increased, and the output can be increased.

(Invention of claim 2) The invention of claim 2 has the following effect in addition to the effect of the invention of claim 1. << 3 >> The swirl chamber entrance can be easily formed. FIG. 1 (B)
As shown in the figure, the inner surface of the ceiling wall (3) of the swirl chamber (2) is formed in a predetermined taper shape, the swirl chamber entrance (4) is formed in a predetermined polygonal shape, and each adjacent side (16) (16) The swirl chamber entrance was formed because the inter-bending part was the spray collision part (11).
By simply forming (4) with a plane parallel to the cylinder center axis (8), the thickness dimension (27) of the spray impingement section (11) can be reduced
It can be longer than the thickness dimension (28) of (20).
Therefore, the swirl chamber inlet (4) can be easily formed.

<< 4 >> The spray fuel can be appropriately burned in the swirl chamber. Suppose the swirl room entrance (4)
When formed in a circular shape, the adjacent spray collision portions (11) (1)
The spray non-collision part (20) located between 1) is arranged on the circumference of the swirl chamber entrance (4). Therefore, the overhang dimension (21) of the ceiling wall (3) from the outermost part (12) of the swirl chamber (2) to the spray non-collision part (20) is shortened, and the swirl air flow (18) containing the spray fuel is reduced. Partially swirl room
It is easy to escape from (2) to the squish space (19). On the other hand, in the present invention, as shown in FIG. 1A, the swirl chamber entrance (4) is formed in a predetermined polygonal shape, and the adjacent sides (16) are formed.
(16) Since the bent portions between the spray collision portions (11) are defined as the spray collision portions (11), the spray non-collision portions (20) located between the adjacent spray collision portions (11) and (11) are on the sides (16) of the polygon. Will be placed in For this reason, the outermost part (12) of the swirl chamber (2)
The overhang dimension (21) of the ceiling wall (3) from the space to the spray non-collision part (20) can be lengthened. In this case, it is difficult for the swirl air flow (18) containing the spray fuel to escape from the swirl chamber (2) to the squish space (19). Therefore, the spray fuel can be appropriately burned in the swirl chamber (2).

[0012]

Embodiments of the present invention will be described with reference to the drawings. 1 and 2 are views for explaining an embodiment of the present invention. In this embodiment, a direct injection combustion chamber of a multi-cylinder vertical diesel engine will be described.

The outline of the combustion chamber is as follows. As shown in FIG. 2 (B), a piston head is attached to the cylinder (22).
(1) is inserted, swirl chamber (2) is installed in piston head (1), and swirl chamber inlet is installed in ceiling wall (3) of swirl chamber (2).
(4) is open. A cylinder head (23) is mounted on the upper part of the cylinder (22), and a multi-hole injection nozzle (5) is mounted on the cylinder head (23). As shown in FIG. 2A, fuel is sprayed in five directions radially from a multi-hole injection nozzle (5).
(6) is performed so that the spray fuel collides with the inner peripheral surface (7) of the swirl chamber inlet (4). As shown in FIG. 1 (A), when viewed in a direction parallel to the cylinder center axis (8), the center axis (10) of the swirl chamber (2) is deviated from the cylinder center axis (8). Spray center point of nozzle (5)
(9) is deviated from the central axis (10) of the swirl chamber (2). The reason why the spray center point (9) of the multi-hole injection nozzle (5) is deviated is that the multi-hole injection nozzle (5) is positioned at the center of the cylinder in order to prevent the multi-hole injection nozzle (5) from interfering with an intake valve or an exhaust valve. This is due to a large deviation from the axis (8).

The fuel spray (6) is started immediately before the compression top dead center, and the spray fuel collides with the inner peripheral surface (7) of the swirl chamber inlet (4). At the time when the fuel spray (6) is performed, the swirl air flow (18) is held in the swirl chamber (2), and the spray fuel is downstream of the swirl air flow (18) under the influence of the swirl air flow (18). It is streamed to the side. For this reason, the flight direction of the fuel spray (6) is shown by curved arrows in FIGS. 1 (A) and 2 (A). The oil droplets of the spray fuel are diffused while being miniaturized gradually in the process of flying, so that the spray fuel has a spreading shape. The swirl air flow (18) held in the swirl chamber (2) is the swirl air flow introduced from the swirl type intake port (not shown) during the intake stroke.
(18) is introduced into the swirl chamber (2) from the swirl chamber inlet (4) in the compression stroke and remains in the swirl chamber (2).

The structure of the swirl chamber (2) is as follows. As shown in FIG. 1 (B), the swirl chamber (2) has a flat inner bottom surface (24) and a projection (25) protruding from the center thereof along the central axis (10) of the swirl chamber (2). It has.
For this reason, the swirl chamber (2) is formed in an annular shape. The central axis (10) of the swirl chamber (2) is formed in a direction parallel to the cylinder central axis (8). Projection (25)
Is to fill the volume of the portion where the swirl air flow (18) does not act and secure an effective internal volume of the swirl chamber (2). The inner surface of the ceiling wall (3) of the swirl chamber (2) is formed in a tapered shape whose inner diameter gradually decreases toward the swirl chamber entrance (4).

The structure of the swirl chamber entrance (4) is as follows. As shown in FIG. 1 (A), the swirl chamber inlet (4) is formed in a pentagonal shape when viewed in a direction parallel to the cylinder center axis (8), and each of the adjacent sides (16) (16) The interior angle (17) is made obtuse, and the bent portion between the adjacent sides (16) (16) is defined as the spray collision portion (11). The spray collision part (11) is formed in an arc shape. Swirl room entrance
The inner peripheral surface (7) of (4) is the central axis (10) of the swirl chamber (2).
Formed in a plane parallel to. Ceiling wall of swirl room (2)
Since the inner surface of (3) is formed in a predetermined tapered shape, the thickness dimension (27) of the spray impingement section (11) is
Becomes thicker than the thickness dimension (28).

The advantages of the above embodiment are as follows.
By increasing the thickness (27) of the spray impingement section (11), it is possible to increase the amount of spray fuel that collides with the spray impingement section (11) and rebounds near the swirl chamber inlet (4). For this reason, the spray fuel can be sufficiently mixed with the air near the swirl chamber inlet (4), and the air utilization rate can be increased. Also,
In this case, the spray fuel is less likely to enter the squish space (19), and the spray fuel can be appropriately burned in the swirl chamber (2). In addition, the thickness dimension (2
8), the swirl chamber (4) has an inner bottom surface (2).
The height dimension (29) from 4) to the ceiling wall (3) forming the spray non-collision portion (20) can be lengthened. For this reason,
A sufficient volume of the swirl chamber (2) can be secured, and air shortage hardly occurs. For these reasons, it is possible to reduce the concentration of unburned harmful components and the concentration of flue gas in exhaust gas. Further, since the concentration of the unburned harmful components and the exhaust gas concentration in the exhaust gas can be reduced, the fuel injection amount can be increased, and the output can be increased. Further, the inner surface of the ceiling wall (3) of the swirl chamber (2) is formed in a predetermined tapered shape, the swirl chamber entrance (4) is formed in a predetermined polygonal shape, and a space between the adjacent sides (16) (16) is formed. The swirl chamber entrance (4) because the bent part is the spray collision part (11)
Simply by forming a plane parallel to the cylinder center axis (8),
The thickness dimension (27) of the spray collision part (11) is adjusted to the spray non-collision part (2).
0) can be made longer than the thickness dimension (28). Therefore, the swirl chamber inlet (4) can be easily formed.

Although the contents of the embodiment of the present invention are as described above, the present invention is not limited to the above embodiment. For example, in the above embodiment, the swirl chamber entrance (4) has a pentagonal shape. In the above embodiment, the interior angle (17) between the adjacent sides (16) (16) is obtuse. However, depending on the shape of the polygon, the interior angle (17) may be a right angle. Good.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a main part of a direct injection combustion chamber of a diesel engine according to an embodiment of the present invention. FIG. 1 (A) is a plan view of a swirl chamber inlet and its peripheral portion, and FIG. It is a BB sectional view of 1 (A).

2 is an overall explanatory view of the combustion chamber of FIG. 1, wherein FIG. 2 (A) is a plan view of a piston, and FIG. 2 (B) is a longitudinal sectional view of the combustion chamber taken along a line BB of FIG. 2 (A). It is.

FIG. 3 is an enlarged view of a main part of a direct injection combustion chamber of a diesel engine according to the prior art, wherein FIG. 3 (A) is a plan view of a swirl chamber inlet and its peripheral portion, and FIG. 3 (B) is FIG. ) Is a cross section taken along line BB.

[Explanation of symbols]

(1) Piston head, (2) Swirl chamber, (3) Ceiling wall, (4) Swirl chamber inlet, (5) Multi-hole injection nozzle,
(6) ... fuel spray, (7) ... inner peripheral surface, (8) ... cylinder center axis, (11) ... spray collision part, (16) ... side, (17) ... inner angle, (20) ... spray non-collision (27): Thickness of the spray collision part, (28): Thickness of the non-collision part.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F02F 3/26 F02F 3/26 CB F02M 61/18 320 F02M 61/18 320Z (72) Inventor Masao Okazaki Sakai, Osaka 3-8 Chikushinmachi Shinmachi, Kubota Sakai Rinkai Plant Co., Ltd. (72) Inventor Yuzo Umeda 3-8 Chikushinmachi Shinmachi, Sakai City, Osaka Prefecture Kubota Sakai Rinkai Plant, Inc. (72) Inventor Yuni Takemura Osaka 3-8 Chikushinmachi Shinmachi, Sakai City Inside Kubota Sakai Rinkai Plant (72) Inventor Akira Iwasaki 3-8 Chikushinmachi Shinmachi, Sakai City, Osaka F-term 3G023 AA04 AB05 AC05 (Reference) AD02 AD06 AD09 3G066 AA07 AB02 AD12 BA16 BA24 BA26 CC34

Claims (2)

[Claims] 1. A swirl chamber (2) is provided in a piston head (1), and a swirl chamber inlet (4) is opened in a ceiling wall (3) of the swirl chamber (2). In a direct injection combustion chamber of a diesel engine, a plurality of fuel sprays (6) are sprayed radially from the engine and the sprayed fuel collides with the inner peripheral surface (7) of the swirl chamber inlet (4). Each spray collision part (11) on the inner peripheral surface (7) of the entrance (4)
The thickness dimension (27) of the adjacent spray collision portions (11) (11)
A direct injection combustion chamber for a diesel engine, wherein the thickness is longer than a thickness dimension (28) of the spray non-collision part (20) located between the two. 2. The direct-injection combustion chamber for a diesel engine according to claim 1, wherein an inner surface of a ceiling wall (3) of the swirl chamber (2) is connected to a swirl chamber inlet.
A polygonal shape having a swirl chamber inlet (4) having four or more sides (16) when viewed in a direction parallel to the cylinder center axis (8), formed in a tapered shape with an inner diameter gradually reduced toward (4). So that the interior angle (17) between the adjacent sides (16) and (16) is obtuse or right angle, and the adjacent sides (16) (1
6) The bends between each other were used as spray collision parts (11).
A direct injection combustion chamber for a diesel engine.