JP2002285848A - Direct injection type combustion chamber for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a range of each spray flight distance from a spray central point 9 of a multihole injection nozzle 5 to each spray collision part 11 on the inner peripheral face 7 of a swirl chamber inlet 4 and unify them to a proper distance. 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 the multihole injection nozzle 5 to collide spray fuel against the inner peripheral face 7 of the swirl chamber inlet 4, and the spray central point 9 of the multihole injection nozzle 5 is made eccentric from the central axial line 10 of a swirl chamber 2, the overhang dimension 15 of a ceiling wall 3 from the outermost part 12 of the swirl chamber 2 on each virtual linear line 13 to the spray collision part 11 becomes longer as an eccentricity distance 14 from the outermost part 12 of the swirl chamber 2 on each virtual linear line 13 to the spray central point 9 becomes longer when the radial virtual linear line 13 from the spray central point 9 of the multihole injection nozzle 5 is assumed.

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
4) is configured to collide with the inner peripheral surface (107).
As shown in (A), when viewed in a direction parallel to the cylinder center axis (108), the spray center point (1
09) is deviated from the central axis (110) of the swirl chamber (102). The deviation of the spray center point (109) of the multi-hole injection nozzle (105)
To avoid (105) interfering with the intake and exhaust valves,
This is because the multi-hole injection nozzle (105) is largely deviated from the cylinder center axis (108). In addition, the code | symbol in FIG.
(118) is a swirl air flow. However, this prior art differs from the present invention in the following points. As shown in FIG. 3A, when viewed in a direction parallel to the cylinder center axis (108), the swirl chamber inlet (104) is formed in a circular shape centered on the center axis (110) of the swirl chamber (102). Therefore, each spray flight distance from the spray center point (109) of the perforated spray nozzle (105) to each spray collision part (111) on the inner peripheral surface (107) of the swirl chamber entrance (104) becomes uneven. .

[0003]

The above prior art has the following problems. << 1 >> The concentration of the unburned harmful components in the exhaust gas increases, and the smoke concentration also increases. Since each spray flight distance from the spray center point (109) of the multi-hole injection nozzle (105) to each spray collision part (111) of the inner peripheral surface (107) of the swirl chamber entrance (104) becomes non-uniform, these are The distance cannot be unified to an appropriate distance, and some are too long or too short. If the spray flight distance is longer than the proper distance,
Before the spray fuel collides with the spray collision section (111), the oil droplets on the outer side of the spray fuel start to burn, and the oil droplets on the inner side tend to cause incomplete combustion due to lack of air. On the other hand, if the injection flight distance is too short than the appropriate distance, the oil droplets of the sprayed fuel collide with the spray collision portion (111) before being sufficiently fined during flight, and adhere to the surface thereof and agglomerate. Vaporization is delayed and incomplete combustion is likely to occur. For these reasons, the concentration of unburned harmful components in the exhaust gas is increased, and the smoke emission concentration is also increased.

<< 2 >> Output is limited. The concentration of unburned harmful components in the exhaust gas increases, and the smoke concentration also increases, so that 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. A plurality of fuel sprays (6) are performed, and the sprayed fuel is caused to collide with the inner peripheral surface (7) of the swirl chamber inlet (4). As shown in FIG. )
The spray center (9) of (5) is aligned with the central axis (1) of the swirl chamber (2).
1), in a direct injection type combustion chamber of a diesel engine, which is deviated from (0), as shown in FIG.
(5) Spray center point (9) to inner surface of swirl chamber entrance (4)
The outermost part of the swirl chamber (2) through the spray collision part (11) of (7)
Assuming a radial virtual straight line (13) leading to (12),
The outermost part (12) of the swirl chamber (2) on each virtual straight line (13)
As the deviation distance (14) from the spray to the spray center (9) becomes longer, the outermost part of the swirl chamber (2) on each virtual straight line (13)
A direct-injection combustion chamber for a diesel engine, wherein the overhang dimension (15) of the ceiling wall (3) from (12) to the spray impingement section (11) is made longer.

(Invention of claim 2) In the direct injection combustion chamber of the diesel engine described in claim 1, FIG.
As shown in the figure, the swirl chamber entrance (4) is formed in a polygonal shape having four or more sides (16) when viewed in a direction parallel to the cylinder center axis (8), and each of the adjacent sides (16) ( 16) Each interior angle (17) between them should be obtuse or right angle, and the bend between adjacent sides (16) (16) should be
(11) A direct injection combustion chamber for a diesel engine, characterized in that:

[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. As shown in FIG. 1, the swirl chamber entrance (4) from the spray center point (9) of the multi-hole injection nozzle (5).
The distance of each spray flight distance to each spray collision part (11) on the inner peripheral surface (7) of the fuel cell can be reduced, and these can be unified to an appropriate distance. After sufficiently miniaturized over the flight distance, each spray collision part
It collides with (11) and bounces off and diffuses into the swirl chamber (2),
Because it is burned while being mixed with the air in the swirl chamber (2),
Incomplete fuel is unlikely to occur. Therefore, it is possible to reduce the concentration of unburned harmful components and the concentration of flue gas in the exhaust gas.

<< 2 >> The output can be increased. Since the concentration of unburned harmful components and the concentration of flue gas in the 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 spray fuel can be appropriately burned in the swirl chamber. Suppose the swirl chamber entrance (4) is the spray center
When formed in a circular shape centered on (9), the spray non-collision part (2) located between the adjacent spray collision parts (11) and (11)
0) is arranged on the circumference of the swirl chamber entrance (4). For this reason, the overhang dimension (2) of the ceiling wall (3) from the outermost part (12) of the swirl chamber (2) to the spray non-collision part (20).
1) Shortened swirl air flow containing atomized fuel (18)
Is easily escaped from the swirl chamber (2) to the squish space (19). Since the squish space (19) has a large heat radiation area per internal volume, proper combustion is not performed here, and most of the fuel escaping there is likely to be discharged without being burned. On the other hand, in the present invention, as shown in FIG. 1 (A), the swirl chamber entrance (4) is formed in a predetermined polygonal shape, and the bent portions between the adjacent sides (16) (16) are sprayed. Each of the adjacent spray collision sections (11) is used as the collision section (11).
Spray non-collision part (20) located between (11) is a polygonal side
(16). For this reason, FIG.
As shown in (1), 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)
And the swirl air flow (18) containing the spray fuel is difficult to escape from the swirl chamber (2) to the squish space (19),
The spray fuel can be appropriately burned in the swirl chamber (2).

[0011]

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. 1A, 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 a swirl chamber (2) in which the swirl air flow (18) does not act.
To secure the effective volume of the swirl chamber (2).

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 a space between the adjacent sides (16) (16) is formed. 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. Seen in a direction parallel to the cylinder center axis (8), the spray center point (9) of the multi-hole injection nozzle (5)
From the inner surface (7) of the swirl chamber entrance (4).
Assuming five imaginary radial straight lines (13) reaching the outermost part (12) of the swirl chamber (2) via 1), each virtual straight line
(13) As the deviation distance (14) from the outermost part (12) of the swirl chamber (2) to the spray center (9) becomes longer, the swirl chamber (2) on each virtual straight line (13) becomes longer. Overhang dimension (15) of ceiling wall (3) from outermost (12) to spray collision part (11)
Is to be longer.

The advantages of the above embodiment are as follows.
The difference in the spray flight distance from the spray center point (9) of the multi-hole injection nozzle (5) to each spray collision portion (11) on the inner peripheral surface (7) of the swirl chamber entrance (4) is reduced, and these are adjusted to an appropriate distance. Therefore, incomplete fuel is unlikely to occur, and the concentration of unburned harmful components in exhaust gas and the concentration of flue gas can be reduced. Therefore, the fuel injection amount can be increased, and the output can be increased. Also, each adjacent side
(16) (16) Spray collision part (11)
Therefore, the spray non-collision part (20) located between the adjacent spray collision parts (11) (11) is arranged on the side (16) of the polygon. For this reason, as shown in FIG.
The overhang dimension (21) of the ceiling wall (3) up to (20) is lengthened, and the swirl air flow (18) containing the spray fuel becomes swirl chamber.
It is difficult to escape from (2) to the squish space (19), and the spray fuel can be appropriately burned in the swirl chamber (2).

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 circumferential surface, (8) ... cylinder center axis, (9) ... spray center point, (10) ... center axis, (11) ... spray collision part, (12) ... Outermost, (13) ... virtual straight line, (14)
... Displacement distance, (15) ... Overhang dimension, (16) ... side, (1
7) ... inside corner.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F02F 3/26 F02F 3/26 CB F02M 61/18 320 F02M 61/18 320Z (72) Inventor Shuichi Yamada 3-8 Chikushinmachi, Sakai-shi, Osaka Inside Kubota Sakai Rinkai Plant Co., Ltd. (72) Inventor Tadao 3-8 Chikushinmachi Shinmachi, Sakai City, Osaka Prefecture Inside Kubota Sakai Rinkai Plant, Inc. (72) Inventor Hiroshi Matsuoka 3-8 Chikushinmachi, Sakai-shi, Osaka Inside Kubota Sakai Rinkai Plant, Inc. (72) Inventor Shogo Muroya 3-8 Chikushinmachi, Sakai-shi, Osaka F-term in Kubota Sakai Coastal Plant, Inc. (reference) 3G023 AA04 AB05 AC05 AD02 AD06 AD09 3G066 AA07 AB02 AD12 BA16 BA24 BA26 CC01 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). A plurality of fuel sprays (6) are made radially from the cylinder, and the sprayed fuel is caused to collide with the inner peripheral surface (7) of the swirl chamber inlet (4). When viewed in a direction parallel to the cylinder center axis (8). The center point (9) of the spray of the multi-hole injection nozzle (5) to the center axis of the swirl chamber (2).
In a direct injection combustion chamber of a diesel engine, which is deviated from (10), the swirl chamber is positioned from the spray center point (9) of the perforated injection nozzle (5) when viewed in a direction parallel to the cylinder center axis (8). Assuming radial virtual straight lines (13) reaching the outermost part (12) of the swirl chamber (2) through the spray collision part (11) on the inner peripheral surface (7) of the entrance (4), each virtual straight line (13) The outermost part (12) of the swirl chamber (2)
As the deviation distance (14) from the spray to the spray center (9) becomes longer, the outermost part of the swirl chamber (2) on each virtual straight line (13)
A direct-injection combustion chamber for a diesel engine, wherein the overhang dimension (15) of the ceiling wall (3) from (12) to the spray impingement section (11) is made longer. 2. The direct injection combustion chamber of a diesel engine according to claim 1, wherein the swirl chamber inlet (4) has four or more sides (16) when viewed in a direction parallel to the cylinder center axis (8). Are formed so that the interior angle (17) between the adjacent sides (16) and (16) is an obtuse angle or a right angle, and each adjacent side (16) (1
6) The bends between each other were used as spray collision parts (11).
A direct injection combustion chamber for a diesel engine.