JP3030491B2 - Diesel engine subchamber combustion chamber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sub-combustion chamber for a diesel engine, and more particularly to a combustion chamber capable of improving combustion.

[0002]

2. Description of the Related Art FIG. 5 shows a prior art of a sub-chamber type combustion chamber of a diesel engine. This has the following basic structure as in the present invention. That is, FIG.
As shown in (G), the main combustion chamber 10
2 and the fuel injection nozzle 1 in the cylinder head 103.
04 is provided, and the main combustion chamber 102 and the sub-chamber 105 are communicated with each other through the communication hole 106.
As shown in (E), the communication hole 106 is composed of a single main communication hole 107 and a plurality of sub-communication holes 108, and each sub-communication hole 108 extends along the peripheral surface over the entire length of the main communication hole 107. In this way, a main-sub communication hole protrusion ridge 109 that protrudes sharply toward the main communication hole 107 is formed at the boundary between the peripheral surface of the main communication hole 107 and the peripheral surface of the sub-communication hole 108. It is.

According to such a configuration, as shown in FIG. 5 (G), compressed air is pushed from the main combustion chamber 102 into the sub-chamber 105 in the compression stroke, and the forced air 1
11 is formed, and the fuel 113
Is injected and mixed with the air in the sub chamber 105, and the fuel 11
3 is burned, and the expansion gas 112 contains unburned fuel.
Blows out from the communication hole 106 to the main combustion chamber 102. The inflation gas 112 is supplied to the main jet 114 that is ejected through the main communication hole 107 and the sub jet 11 that is ejected through the sub communication hole 108.
5

[0005] In the prior art shown in FIG.
Between the main and sub communication holes adjacent to each other with the peripheral surface portion 107a interposed therebetween
09.109 are formed in parallel.

[0005]

In the prior art shown in FIG. 5, excellent performance can be obtained by good combustion, but there are the following problems. That is, the peripheral surface portion 10 of the main communication hole 107
Since the ridges 109 between the main and sub communication holes which are adjacent to each other with the 7a interposed therebetween are formed in parallel, the sub jets 108 guided by the ridges 109 between the main and sub communication holes are formed in the main combustion chamber. It is only ejected in parallel toward 102, and its diffusion efficiency in the side direction is low. Therefore, it is required to improve the combustion by promoting the diffusion efficiency of the sub jet 108.

An object of the present invention is to provide a sub-combustion type combustion chamber of a diesel engine capable of improving combustion.

[0007]

As shown in FIG. 1 (G), the present invention provides a sub-chamber in which a main combustion chamber 2 is provided in a cylinder 1 and a fuel injection nozzle 4 faces a cylinder head 3. 5
Is provided, and the main combustion chamber 2 and the sub chamber 5 are communicated with each other through the communication hole 6,
As illustrated in FIGS. 1A to 1E, the communication hole 6 includes a single main communication hole 7 and a plurality of sub-communication holes 8, and each sub-communication hole 8 is formed of the main communication hole 7. By extending along the peripheral surface over the entire length, a ridge between the main / sub communication holes protrudes sharply toward the main communication hole 7 at the boundary between the peripheral surface of the main communication hole 7 and the peripheral surface of the sub communication hole 8. In the sub-chamber type combustion chamber of a diesel engine, which is constituted by forming No. 9, the following is characterized.

That is, as exemplified in FIG. 1 (F),
It is characterized in that the separation width 10 between the ridges 9 between the main and sub communication holes adjacent to each other across the peripheral surface portion 7a of the main communication hole 7 gradually decreases as approaching the main combustion chamber 2.

[0009]

According to the present invention, as shown in FIG. 1 (F), the auxiliary jets 15, 15 are brought closer to the main combustion chamber 2 by the guide of the ridges 9, 9 between the adjacent main and sub communication holes. Therefore, the jets gradually approach each other and collide with each other in the main combustion chamber 2, and the repulsive force causes the sub jets 15 to be forcibly diffused in the lateral direction, thereby increasing the diffusion efficiency. For this reason, the main combustion chamber 2
The mixing of the inflation gas 12 with the air at the stage is improved, and the combustion is significantly improved.

[0010]

According to the present invention, the following effects can be obtained. Compared to the case where the ridges between the adjacent main and sub communication holes are parallel, the mixing of the expansion gas and the air in the main combustion chamber becomes better, and the combustion is remarkably improved. Therefore, it is possible to improve output, reduce fuel consumption, reduce harmful exhaust components, and the like.

Since it is only necessary to devise the sub-communication holes so that the separation width of the adjacent ridges between the main and sub-communication holes becomes gradually smaller as approaching the main combustion chamber, it can be easily manufactured by a simple modification of an existing engine. it can.

[0012]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining a first embodiment of the present invention. In this embodiment, a vertical diesel engine of a vortex combustion chamber type is used, and its configuration is as follows. That is, FIG.
As shown in FIG. 1, a main combustion chamber 2 is provided in a cylinder 1 and a sub-chamber 5 facing a fuel injection nozzle 4 is provided in a cylinder head 3, and the main combustion chamber 2 and the sub-chamber 5 are communicated through a communication hole 6. As shown in FIGS. 1 (A) to 1 (E), the communication hole 6 is composed of a single main communication hole 7 and a plurality of sub communication holes 8, and each sub communication hole 8 is defined by the main communication hole 7. Of the main communication hole 7 and the peripheral surface of the sub communication hole 8 at the boundary between the peripheral surface of the main communication hole 7 and the peripheral surface of the sub communication hole 8 so as to protrude sharply toward the main communication hole 7. Article 9 is formed.

According to this structure, as shown in FIG. 1 (G), compressed air is pushed from the main combustion chamber 2 into the sub-chamber 5 in the compression stroke, and a forced flow 11 is formed in the sub-chamber 5. The fuel 13 is injected from the fuel injection nozzle 4 and the sub chamber 5
The fuel 13 is mixed with the air inside, and a part of the fuel 13 burns, and the expansion gas 12 containing the unburned fuel blows out from the communication hole 6 into the main combustion chamber 2. The inflation gas 12 is composed of a main jet 14 ejected through the main communication hole 7 and a sub jet 15 ejected through the sub communication hole 8.

As shown in FIG. 1 (G), the main combustion chamber 2
It is provided between the cylinder head 3 and the piston head 21. The sub-chamber 5 is as follows. That is, a hollow portion 23 is provided inside the thick wall 22 of the cylinder head 3, a communication hole base 24 is fitted into the hollow portion 23 from below, and a hemispherical ceiling surface of the hollow portion 23 and the communication hole base 24 are formed. The spherical sub-chamber 5 is formed with the hemispherical recessed portion 25 of FIG. Sub-room 5
The communication hole 6 is provided at a position eccentric from the cylinder center axis 26, and the communication hole 6 faces the center of the cylinder 1.
The communication hole 6 is directed toward the spherical surface 5a near the cylinder peripheral wall of the sub-chamber 5, and is inclined in the tangential direction to form the sub-chamber 5 as an eddy chamber. The fuel injection nozzle 4 is fixed to the wall 22 of the cylinder head 3. The communication hole 6 is provided in the communication hole base 24.

In this embodiment, in order to improve combustion,
The following configuration was adopted. That is, as shown in FIG. 1 (F), the separation width 10 of the ridges 9 between the main and sub communication holes adjacent to each other across the peripheral surface portion 7 a of the main communication hole 7 gradually decreases as approaching the main combustion chamber 2. It is made to become.

According to such a configuration, as shown in FIG. 1 (F), the sub jets 15 come closer to the main combustion chamber 2 by the guide of the adjacent ridges 9 between the main and sub communication holes. , And gradually collide with each other in the main combustion chamber 2, and the repulsive force causes the sub jets 15 to be forcibly diffused in the side direction, thereby increasing the diffusion efficiency. For this reason, the mixing of the inflation gas 12 and the air in the main combustion chamber 2 becomes better as compared with the case where the ridges 9 between the adjacent main and sub communication holes are parallel,
Combustion is significantly improved.

As shown in FIGS. 1C to 1E, the basic shape of the main communication hole 7 is cylindrical, and as shown in FIG.
The main communication hole center axis 27 is inclined at an elevation angle of 45 ° with respect to the bottom surface 28 of the communication hole base 24. As shown in FIG. 1 (A), assuming a virtual plane that includes the main communication hole center axis 27 and is parallel to the cylinder center axis 26, the main communication hole center is viewed in a direction orthogonal to the virtual plane. Assuming that the axis line 27 is a boundary line, the peripheral surface of the main communication hole 7 is located close to the cylinder center.
1 and a peripheral surface 32 near the cylinder peripheral wall, and the sub-communication hole 8 is arranged only on the peripheral surface 31 near the cylinder center.

In this embodiment, as shown in FIGS. 1 (C) to 1 (E), a total of four sub-communication holes 8 are provided, and they are adjacent to each other with two peripheral portions 7a of the main communication hole 7 interposed therebetween. The two pairs of ridges 9 between the main and auxiliary communication holes gradually approach each other as they approach the main combustion chamber 2. The protruding ridges 9 between the main and sub communication holes are converged at the main combustion chamber side end 9a.
Each peripheral surface portion 7a is formed in a triangular shape. Therefore, the sub jets 15 immediately after being injected from the sub communication holes 8 come into contact with each other at a high speed in the main combustion chamber 2, and the diffusion of the expansion gas 12 in the main combustion chamber 2 is further promoted, and the combustion is further improved. Is done.

The basic shape of the main communication hole 7 is cylindrical, but as shown in FIG.
As for a, since the cylindrical peripheral surface is formed by slightly shaving it, it slightly deviates from the cylindrical peripheral surface, which is the basic shape, toward the cylinder center axis 26. Reference numeral 33 in FIG. 1 (D) denotes a cylindrical outer peripheral line which is a basic shape of the main communication hole 7 when viewed in a direction parallel to the main communication hole central axis 27.

In this embodiment, as shown in FIGS. 1 (C) to 1 (E), the peripheral surface of the sub-communication hole 8 is formed as a tapered surface which gradually decreases toward the sub-chamber 5, and the passage of the communication hole 6 is formed. The cross-sectional area gradually decreases as approaching the sub-chamber 5. For this reason, the compressed air passing through the communication hole 6 is gradually accelerated, the speed of the pushing flow 11 is increased, the mixing of the air and the fuel 13 in the sub-chamber 5 is promoted, and the combustion is significantly improved. Incidentally, the tapered auxiliary communication hole 8 can be easily formed by a taper reamer or the like.

In this embodiment, as shown in FIG. 1 (G), a fan-shaped inflatable gas guide groove 35 is formed on the top surface of the piston head 21. This inflation gas guide groove 35 is
When viewed in a direction parallel to the cylinder center axis 26, the starting end 36 is formed at a position overlapping the communication hole 6.
, The depth gradually decreases as the distance from the cylinder toward the cylinder central axis 26 increases, and the width increases. For this reason, the expansion gas 12 blown out from the communication hole 6 to the main combustion chamber 2 is throttled by raising the bottom of the expansion gas guide groove 35, and is accelerated. The gas is smoothly guided into the inner end space 2a of the main combustion chamber 2 located therein, and is also smoothly expanded in the width direction of the expansion gas guide groove 35.
The mixing of the inflation gas 12 and the air at the step becomes good.

The second to fourth embodiments of FIGS. 2 to 4 are modifications of the first embodiment. In the first embodiment shown in FIG.
There are two pairs of the ridges 9 between the main and sub communication holes which approach each other, whereas in the second embodiment of FIG. 2, the number of the sub communication holes 8 is the same, but they approach each other. Projection between main and auxiliary communication holes 9.9
In the third embodiment of FIG. 3 or the fourth embodiment of FIG. 4, there are two pairs of sub-communication holes 8 and one pair of ridges 9 between the main and sub-sub communication holes approaching each other. The points are different.

In the first embodiment shown in FIG. 1, the ridges 9 between the main and sub communication holes approaching each other are converged at the end 9a on the main combustion chamber side, and the peripheral surface portion 7a sandwiched therebetween is triangular. On the other hand, in the fourth embodiment shown in FIG. 4, the ridges 9 between the main and sub communication holes do not converge at the main combustion chamber side end 9a, but are sandwiched between them. The difference is that the peripheral portion 7a is trapezoidal. Except for these, it is the same as the first embodiment of FIG. 2 to 4, the same elements as those of the first embodiment are denoted by the same reference numerals.

In order to effectively diffuse the inflation gas 12 by contact between the sub jets 15, it is desirable that the number of the ridges 9 between the main and sub communication holes approaching each other is two or more. It is more desirable that the number be more than the pair. It is desirable that the ridges 9 between the main and sub communication holes approaching each other converge at the main combustion chamber side end 9a.

Although the contents of the embodiments of the present invention are as described above, the contents of the present invention are not limited to the above embodiments. For example, the shape of the main communication hole 7 and the sub communication hole 8 may be a shape other than that shown in each embodiment. Room 2
The side may have a rectangular column shape, the peripheral surface of the main communication hole 7 may have a tapered surface that decreases toward the sub chamber 5, or the sub communication hole 8 may have a columnar, elliptical, or prismatic shape. The plurality of sub-communication holes 8 may be arranged only on the peripheral surface 32 of the main communication hole 7 near the cylinder peripheral wall shown in FIG. 1A, or the peripheral surface 31 near the cylinder center and the peripheral surface 32 near the cylinder peripheral wall. May be arranged in both. The sub chamber 5 is not limited to the swirl chamber, but may be a pre-combustion chamber.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a first embodiment of the present invention.
FIG. 1A is a longitudinal sectional view of a communication hole base, and FIG.
1A is an enlarged view of a main part, FIG. 1C is a perspective view of a communication hole, and FIG. 1D is a view of the communication hole as viewed in the direction of arrow D in FIG.
(E) is a view of the communication hole as viewed in the direction of arrow E in FIG. 1 (B), and FIG. 1 (F).
Is a schematic diagram for explaining contact between sub jets, and FIG. 1 (G) is a longitudinal sectional view of a sub chamber combustion chamber.

FIG. 2 is a diagram for explaining a second embodiment of the present invention.
2A is a diagram corresponding to FIG. 1C, FIG. 2B is a diagram corresponding to FIG. 1D, and FIG. 2C is a diagram corresponding to FIG.

FIG. 3 is a diagram for explaining a third embodiment of the present invention.
3A is a diagram corresponding to FIG. 1C, FIG. 3B is a diagram corresponding to FIG. 1D, and FIG. 3C is a diagram corresponding to FIG.

FIG. 4 is a diagram for explaining a fourth embodiment of the present invention.
4A is a diagram corresponding to FIG. 1C, FIG. 4B is a diagram corresponding to FIG. 1D, and FIG. 4C is a diagram corresponding to FIG.

FIG. 5 is a diagram for explaining a conventional technique, and FIG.
5A is a diagram corresponding to FIG. 5B, FIG. 5B is a diagram corresponding to FIG.
(C) is a diagram corresponding to FIG. 1 (C), FIG. 5 (D) is a diagram corresponding to FIG. 1 (D), FIG. 5 (E) is a diagram corresponding to FIG. 1 (E), and FIG. FIG. 5G is a diagram corresponding to FIG. 1G.

[Explanation of symbols]

1 ... cylinder, 2 ... main combustion chamber, 3 ... cylinder head, 4
... fuel injection nozzle, 5 ... sub-chamber, 6 ... communication hole, 7 ... main communication hole, 7a ... peripheral surface portion, 8 ... sub-communication hole, 9 ... ridge between main and sub-communication holes, 10 ... separation width.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-26957 (JP, A) JP-A-7-11957 (JP, A) JP-A-52-39308 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) F02B 19/08-19/18

Claims (1)

(57) [Claims] A main combustion chamber (2) is provided in a cylinder (1),
A subchamber (5) facing the fuel injection nozzle (4) is provided in the cylinder head (3), and a communication hole is provided between the main combustion chamber (2) and the subchamber (5).
(6), and this communication hole (6) is connected to a single main communication hole (7).
And a plurality of sub-communication holes (8), and each sub-communication hole (8) is formed along the peripheral surface over the entire length of the main communication hole (7), so that the peripheral surface of the main communication hole (7) A sub-chamber of a diesel engine, which is formed by forming a ridge (9) between main and sub-communication holes that protrudes sharply toward the main communication hole (7) at a boundary with the peripheral surface of the sub-communication hole (8). In the type combustion chamber, the separation width (10) of the ridges (9) between the main and sub communication holes adjacent to each other across the peripheral surface portion (7a) of the main communication hole (7) approaches the main combustion chamber (2). Therefore, a sub-chamber type combustion chamber of a diesel engine characterized in that the combustion chamber is gradually reduced in size.