JP3344950B2 - Diesel engine communication hole base with sub-chamber 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 diesel engine in which a main combustion chamber and a sub-chamber are connected by a communication hole including one main communication hole and a plurality of sub-communication holes. The present invention relates to improvement of a communication hole base.

[0002]

2. Description of the Related Art As a prior art of the above-mentioned diesel engine, for example, there is one shown in FIG. That is, as shown in FIG. 4 (G), the engine has a main combustion chamber (102) in a cylinder (101) and a sub-fuel injection nozzle (104) facing a cylinder head (103). The main combustion chamber (102) and the sub-chamber (105) are provided with communication holes (10
It communicates with 6). The communication holes (106) are shown in FIGS.
As shown in (E), it is composed of one main communication hole (107) and two sub communication holes (108). Then, by arranging the sub-communication holes (108) along the peripheral surface over the entire length of the main communication hole (107), the peripheral surface of the main communication hole (107) and the sub-communication hole
A protruding ridge (109) between the main and sub communication holes which protrudes sharply toward the main communication hole (107) is formed at the boundary with the peripheral surface of the (108).

According to this structure, as shown in FIG. 4 (G), in the compression stroke, the compressed air in the main combustion chamber (102) is pushed into the sub chamber (105) through the communication hole (106). , Its sub-room (10
5) A forced flow (111) is formed inside. Further, as shown in FIG. 4 (F), in the compression stroke, the ridge between the main and sub communication holes (109)
Each translational flow (114) blowing from both sides of the sub-chamber side end (109a) of
Is trapped in the translational flows (114) to form minute turbulences (112). And the fuel (113) injected from the fuel injection nozzle (104),
The mixture is agitated by the pushing flow (111) and the minute turbulence (112), and is well mixed with the air in the sub-chamber (105), whereby good combustion can be obtained.

In the above-mentioned engine, in order to obtain the above-mentioned good combustion, it is necessary to form the above-mentioned ridge (109) between the main and sub communication holes with high accuracy. For this reason, the communication hole base (124) forming the lower half of the sub chamber (105) is cast by, for example, the lost wax method. That is, a wax model is manufactured by injecting wax into a mold, and the mold is removed from the wax model, and the wax model is coated with a refractory material. Next, after putting the wax model in a braid and filling the periphery with sand, the wax is melted and discharged to produce a mold, and the molten metal is poured into the mold to form the communication hole base (124).
Casting.

[0005]

However, the casting of the communication hole base (124) has the following problems. That is, the main communication hole (107) is formed in a columnar shape, while the sub-communication hole (108) has a central axis that promotes diffusion of the combustion gas to the entire main combustion chamber (102). From the sub-chamber (105) toward the main combustion chamber (102), the main communication hole (107) gradually moves in the left and right diagonal direction (in the vertical diagonal direction in FIG. 4 (D)), and from the sub-chamber (105). The passage is formed in a tapered shape such that the cross-sectional area of the passage increases toward the main combustion chamber (102).

Therefore, in the mold for manufacturing the wax model, the core forming the main communication hole (107) is formed in a cylindrical shape, and the core forming the sub communication hole (108) is tapered. It is formed in a shape. After the production of the wax model, the core for the main communication hole (107) and the core for each sub-communication hole (108) are to be extracted from the wax model, respectively, as described above. The core for the main communication hole (107) is
Because of the cylindrical shape, it can be extracted only in one direction.
Further, as described above, since the central axis of each sub-communication hole (108) extends obliquely with respect to the main communication hole (107),
The core for (108) is extracted in a diagonal left and right direction with respect to the extraction direction of the core for the main communication hole (107). In other words, each of the cores has to be separated and extracted in three directions, so that it takes time to manufacture the wax model, and the casting of the communication hole base (124) is costly. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a diesel engine capable of reducing the time required for casting a communication hole base provided with a communication hole communicating the main combustion chamber and the sub chamber.

[0008]

Means for Solving the Problems [Invention of claim 1] The invention of claim 1 is, for example, shown in FIG.
As shown in FIG. 3, the configuration is as follows. A main combustion chamber (2) is provided in a cylinder (1), and a communication hole base (24) is fitted into a hollow part (23) recessed in a cylinder head (3) to form a sub chamber (5). The main combustion chamber (2) and the sub chamber (5) are communicated by the communication hole (6) provided in the communication hole base (24),
The communication hole (6) is composed of one main communication hole (7) and a plurality of sub communication holes.
(8), and by arranging each sub-communication hole (8) along the peripheral surface of the main communication hole (7), the peripheral surface of the main communication hole (7) and the sub-communication hole (8) are formed. ) Is formed on the boundary with the peripheral surface of the main combustion hole (7) to protrude sharply toward the main communication hole (7). A casting using a wax model (33) is used to cast the hole cap (24), and the main communication hole (7) is inserted from the sub chamber (5) to the main combustion chamber.
(2) The cross-sectional area of the passage is increased in a tapered shape as it goes toward (2), and the sub-communication hole (8) is formed in a columnar shape.
Among the molds for producing the wax model (33), a tapered core (31) for forming the main communication hole (7) and at least one auxiliary communication hole.
The positions of the main communication hole (7) and the at least one sub-communication hole (8) are set so that the cylindrical core (32) forming (8) can be extracted in parallel in the same direction. Things.

[Invention of claim 2] The invention of claim 2 is the same as the above-mentioned invention of claim 1, but further configured as follows. Of the plurality of sub-communication holes (8), at least two of the sub-communication holes (8) are configured so that the central axes (28) are parallel to each other, and the tapered shape that forms the main communication hole (7). Child (31) and the at least two sub-communication holes
The positions of the main communication hole (7) and the at least two sub-communication holes (8) are set such that the cylindrical core (32) forming (8) can be extracted in parallel in the same direction. Things.

[0010]

The invention of claim 1 operates as follows, for example, as shown in FIGS. That is,
The main communication hole (7) is tapered so that the passage cross-sectional area increases from the sub-chamber (5) toward the main combustion chamber (2). ). Therefore, in the compression step, the compressed air is gradually accelerated while passing from the main combustion chamber (2) through the main communication hole (7), and the translation flow (14) shown in FIG. As a result, the amount of the small turbulent flow (12) generated in the sub-chamber (5) increases, and the speed of the pushing flow (11) in the sub-chamber (5) also increases. As a result, the mixing performance of the fuel (13) and the air in the sub chamber (5) is improved.

In the combustion step, the combustion gas (37) ignited and expanded in the sub-chamber (5) is blown out from the sub-chamber (5) to the main combustion chamber (2) through the communication hole (6). At that time, the combustion gas (3
Most of 7) goes to the main combustion chamber 2 while expanding by passing through the tapered main communication hole 7. Further, a part of the combustion gas (37) passes through the sub-communication hole (8) arranged along the peripheral surface of the main communication hole (7), thereby forming the center of the main communication hole (7). Main combustion chamber away from axis (27)
Go to (2). Thereby, the combustion gas (37) spreads over the entire main combustion chamber (2).

On the other hand, in order to generate the small turbulent flow (12) satisfactorily, the main and sub communication holes formed at the boundary between the peripheral surface of the main communication hole (7) and the peripheral surface of the sub communication hole (8) are required. It is necessary to manufacture the ridge (9) with high accuracy. Therefore, the communication hole base (24) provided with the communication hole (6) is cast by, for example, a lost wax method. In the casting by the lost wax method, a mold for producing a wax model (33) [see FIG. 3] used for casting the communication hole base (24) has a tapered main communication hole (7). Since the sub-communication hole (8) is formed in a columnar shape, the core (31) forming the main communication hole (7) is tapered and the sub-communication hole (8) is formed. The child (32) becomes cylindrical. And a core (31) for forming the main communication hole (7).
Can be pulled out along the peripheral surface of the core (31) in an oblique direction with respect to the center axis of the core (31) because of the tapered shape. Further, since the sub communication hole (8) is arranged along the peripheral surface of the main communication hole (7), the central axis (28) of the sub communication hole (8) is aligned with the main communication hole. Becomes parallel to the ridge (9).

For this reason, the cores (31) and (32) are
When extracting from 3), the core that forms the main communication hole (7)
(31) in the same direction as the core (32) forming the sub-communication hole (8)
[The direction of the central axis (28) of the sub-communication hole (8)] can be extracted [see the two-dot chain line diagram in FIG. 3]. At this time, the cores (31) and (32) are ridges between the main and sub communication holes in the wax model (33).
The core (31), (32) is extracted by removing the cores (31), (32) along the direction in which the part (29) constituting the part (29) extends. The shape of (29) is not broken.

[Claim 2] The invention of claim 2 operates in the following manner in addition to the effect of the invention of claim 1. A core for forming at least two of the sub-communication holes (8) so that the central axes (28) of at least two of the sub-communication holes (8) are parallel to each other, and forming the sub-communication holes (8). The posture of the main communication hole (7) and the sub communication hole (8) is set so that the core communication hole (32) can be extracted in the same direction as the core (31) forming the main communication hole (7). In case, those parallel sub-communication holes
The core (32) forming (8) and the core (3) forming the main communication hole (7)
Even if 1) is pulled out in parallel in the same direction, the main communication hole
The shape of the portions (29) constituting the ridges (9) between the main and sub communication holes at the boundary between the peripheral surface of (7) and the peripheral surface of the parallel sub communication hole (8) is not broken.

[0015]

[Embodiment 1] The invention of the above-described embodiment 1 has the following effects because it is configured and operates as described above. That is, since the main communication hole is formed in a tapered shape in which the passage cross-sectional area increases from the sub-chamber to the main combustion chamber, the compressed air passing through the main communication hole is gradually accelerated in the compression step, and the minute air in the sub-chamber is reduced. In addition to increasing the amount of turbulence generated, the speed of the forced flow is also increased, and the mixing performance of fuel and air in the sub-chamber is improved. Moreover, in the combustion step, the combustion gas spreads toward the main combustion chamber while passing through the tapered main communication hole, and moves toward the main combustion chamber while being separated from the central axis of the main communication hole by passing through the sub communication hole. Therefore, the combustion gas spreads over the entire main combustion chamber, and the air in the main combustion chamber is effectively used. This significantly improves the combustion performance.

When the mold is extracted from the wax model used for casting the communication hole base, the core forming the sub communication hole and the core forming the main communication hole are connected to the main and sub communication in the wax model. The portions corresponding to the inter-hole ridges can be simultaneously extracted in the same direction without breaking. Therefore, while ensuring the formation of the ridge between the main and sub communication holes, the labor required for manufacturing the wax model can be reduced, and the productivity of the wax model can be improved.

[Claim 2] The invention of claim 2 has the following effects since it is configured and operates as described above.
The cores forming the sub-communication holes and the cores forming the main communication holes can be simultaneously extracted in the same direction by the number of the parallel sub-communication holes. While the formation of the wax model can be reliably ensured, the labor required for manufacturing the wax model can be further reduced, and the productivity of the wax model can be further improved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a diesel engine having a sub-chamber combustion chamber according to the present invention will be described below with reference to FIGS. FIG. 1A is a longitudinal sectional view of a communication hole base of the diesel engine, and FIG.
1 (A) is an enlarged view of a main part of FIG. 1 (A), FIG. 1 (C) is a perspective view of a communication hole of the diesel engine, FIG. 1 (D) is a view in the direction of arrow D in FIG. FIG. 1E is a view in the direction of arrow E in FIG. 1B, and FIG. 1F is a perspective view illustrating the principle of generation of minute turbulence generated in the sub-chamber of the diesel engine. FIG.
FIG. 2 is a longitudinal sectional view showing a main part of the sub-chamber type combustion chamber. FIG. 3 is a view illustrating a state in which a core forming a communication hole according to the sub-chamber type combustion chamber is extracted from a wax model, as shown in FIG.
FIG. 2 is a sectional view taken along line II.

That is, as shown in FIG. 2, a piston (21) is arranged in a cylinder (1) of the engine so as to be able to move up and down, and a cylinder head (3) is provided above the cylinder (1).
Is attached. A main combustion chamber (2) is provided between the piston head of the piston (21) and the lower surface of the cylinder head (3). In addition, the cylinder head
Inside (3) is a sub-chamber facing the nozzle of fuel injection nozzle (4).
A sub-chamber (5) is connected to the main combustion chamber (2) through a communication hole (6). The fuel injection nozzle (4) is fixed to the wall (22) of the cylinder head (3).

The communication hole (6) is composed of one main communication hole (7) and two sub communication holes (8) as shown in FIGS. . The main communication hole (7) is provided in the sub-chamber.
The passage is formed in a tapered shape (a truncated cone shape) in which the cross-sectional area of the passage increases from (5) toward the main combustion chamber (2), and the sub-communication hole (8) is formed in a columnar shape. Also,
Each sub communication hole (8) is arranged along the peripheral surface of the main communication hole (7), whereby the peripheral surface of the main communication hole (7) and the sub communication hole are
At the boundary with the peripheral surface of (8), a protruding ridge (9) between the main and sub communication holes which protrudes sharply toward the main communication hole (7) is formed. The central axis (28) of the sub communication hole (8) is parallel to the ridge (9) between the main and sub communication holes (see FIG. 3).

As shown in FIG. 2, the sub-chamber (5) and the communication hole (6) are located on the peripheral side of the cylinder (1) with respect to the cylinder center axis (26) [right side in FIG. The eccentric position is provided. Further, the communication hole (6) is provided in the main combustion chamber (2).
Side faces the center of the cylinder (1) and the subchamber (5)
The side is inclined so as to face the spherical surface (5a) near the cylinder peripheral wall of the sub-chamber (5), so that the communication hole (6) substantially follows the tangential direction of the sub-chamber (5). The above communication hole
As shown in FIG. 1 (E), the opening on the side of the main combustion chamber (2) in FIG. 6 (6) has left and right ends of a main communication hole (7) and a sub communication hole (8) [FIG. The upper and lower ends in the parentheses) are cut out in a shape where they are connected by tangent lines.

On the other hand, a fan-shaped expansion gas guide groove (35) is formed in the piston head of the piston (21), and a starting end (36) of the expansion gas guide groove (35) is connected to the communication hole (35). It is formed at a position almost overlapping with the extension of 6). Further, the inflation gas guide groove (35) extends from its starting end (36) to the cylinder center axis.
(26) As it goes to the side, its depth becomes gradually shallower and its width becomes wider.

The sub chamber (5) is formed in the cylinder head (3) as follows. That is, the cylinder head (3)
A cavity (23) is recessed in the wall (22) on the lower surface side of the above, and the sub-chamber (5) is formed by fitting a communication hole base (24) into the cavity (23). I have. That is, the hollow part (23) has a hemispherical ceiling surface, and the communication hole base (24) has
A hemispherical recess (25) is formed on the upper surface. Then, by fitting the communication hole mouthpiece (24) into the hollow portion (23) as described above, a spherical sub-chamber (5) as shown in FIG. 2 is formed. The communication hole (24) is provided with the communication hole (6).

According to such a configuration, in the compression stroke, the compressed air in the main combustion chamber (2) passes through the communication hole (6) and the sub-chamber (5).
In the sub-chamber (5).
1) is formed. As shown in FIG. 1 (F), the vicinity of the end (9a) on the sub-chamber side of the ridge (9) between the main / sub communication holes [FIG.
A small turbulence (12) is formed on the left side in (F). That is, the small turbulent flow (12) is formed by the air interposed between the respective translational flows (14) blown out from both sides of the sub-chamber side end (9a) of the ridge (9) between the main and sub communication holes. Are caused by being caught in the respective translational flows (14). And the fuel injection nozzle (4)
Is injected by the pushing flow (11) and the minute turbulence (12) and is well mixed with the air in the sub-chamber (5).

On the other hand, in the combustion step, the combustion gas (37) ignited and expanded in the sub-chamber (5) is blown out of the sub-chamber (5) to the main combustion chamber (2) through the communication hole (6). At that time, the combustion gas (3
Most of 7) goes to the main combustion chamber 2 while expanding by passing through the tapered main communication hole 7. In addition, a part of the combustion gas (37) passes through each of the columnar sub-communication holes (8), so that the combustion gas (37) obliquely extends from the center axis (27) of the main communication hole (7) in the right and left direction [FIG. E), heading toward the main combustion chamber (2). That is, a part of the combustion gas (37) is
By passing through each sub-communication hole (8), it is directed in the left-right direction in the main combustion chamber (2), whereby the combustion gas (37) can be more reliably spread in the left-right space in the main combustion chamber (2). it can.

The main communication hole (7) and each sub communication hole
(8) and the combustion gas (37) blown out to the main combustion chamber (2)
Flows into the starting end (36) of the expansion gas guide groove (35), and the expansion gas guide groove (35) allows the cylinder center axis (26) to flow.
On the opposite side of the communication hole (6) [left side in FIG. 1 (G)]
Is smoothly guided to the inner end space (2a) side of the main combustion chamber (2) located at Further, the combustion gas (37) directed in the left-right direction in the main combustion chamber (2) by passing through each sub-communication hole (8),
The gas smoothly spreads along the expansion gas guide groove (35) and flows in the left-right direction in the main combustion chamber (2). As a result, the combustion gas (37) spreads quickly and uniformly throughout the main combustion chamber (2), and the combustion gas (37) and the air mix well in the main combustion chamber (2). This effectively utilizes the air in the main combustion chamber (2) in the combustion process.

Also, in order to generate the above-mentioned minute turbulent flow (12) satisfactorily, it is necessary to form the ridges (9) between the main and sub communication holes with high precision. For example, it is cast by the lost wax method described in the section of the prior art. In the casting by the lost wax method, as shown in FIG. 3, a mold for producing a wax model (33) used for casting the communication hole die (24) is provided with the main communication hole (7).
The core [hereinafter referred to as the core for the main communication hole] (31) is formed in a tapered shape, and the core [hereinafter, the core for the sub communication hole] forming each of the sub communication holes (8) is formed. (32) is formed in a columnar shape. The cores (31) and (32) are integrally formed.

Then, the cores (31) and (32) are replaced with a wax model (33).
When the cores (31) and (32) are taken out from the auxiliary communication hole (8), as shown in a two-dot chain line diagram in FIG.
Pulled out in the same direction as 8). At this time, as described above, the central axis (28) of the sub-communication hole (8) and the ridge between the main and sub-communication holes are used.
Since (9) is parallel to the wax model (33), the cores (31) and (32) are removed from the wax model (33) along the central axis (28) of the sub-communication hole (8). 33) Projection between main and sub communication holes (9)
The part (29) corresponding to is not broken.

The center axis of the two sub-communication holes (8)
When the cores (28) are configured to be parallel to each other, the cores forming the two sub-communication holes (8) and the core for the main communication hole (31) are integrally formed. The core can be removed at the same time, but is not limited to this.
The central axes 28 of the sub communication holes 8 need not be parallel to each other. In this case, only the core forming one sub-communication hole (8) and the core (31) for the main communication hole are, for example, integrally extracted in the same direction to form the other sub-communication hole (8). The core will be extracted separately. Further, in the above description, two sub-communication holes (8) are provided, but the present invention is not limited to this, and three or more sub-communication holes (8) may be provided.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a diesel engine provided with a sub-chamber type combustion chamber according to the present invention, and FIG.
1 is a longitudinal sectional view of a communication hole base of the diesel engine, FIG. 1B is an enlarged view of a main part of FIG. 1A, FIG. 1C is a perspective view of a communication hole of the diesel engine, FIG. (D)
1 (B) is a view in the direction of arrow D, FIG. 1 (E) is a view in the direction of arrow E in FIG. 1 (B), and FIG. 1 (F) is a microturbulence generated in the sub-chamber of the diesel engine. FIG. 3 is a perspective view for explaining the principle of occurrence of phenomena.

FIG. 2 is a longitudinal sectional view showing a main part of the sub-chamber type combustion chamber.

FIG. 3 (D) of FIG. 1 (D) for explaining a state in which a core forming a communication hole according to the sub-chamber type combustion chamber is extracted from a wax model.
FIG. 3 is a sectional view taken along the line III.

FIG. 4 is a diagram for explaining a conventional technique, and FIG.
4 (A), FIG. 4 (B) is a diagram corresponding to FIG. 1 (B), FIG. 4 (C) is a diagram corresponding to FIG. 1 (C), FIG. 4 (D) is a diagram corresponding to FIG. 1 (D), FIG. (E) is a diagram corresponding to FIG. 1 (E), FIG. 4 (F) is a diagram corresponding to FIG. 1 (F), FIG. 4 (G)
Is a view corresponding to FIG.

[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, 8 ... multiple sub-communication holes, 9 ... ridge between main and sub-communication holes, 24 ...
The base of the communication hole, 31 ... The core that forms the main communication hole, 32 ... The core that forms the sub communication hole, 33 ... The wax model.

──────────────────────────────────────────────────続 き Continued on the front page (72) Keita Naito, 64 Ishizukita-machi, Sakai-shi, Osaka, Japan Inside Kubota Sakai Works, Inc. References JP-A-61-171822 (JP, A) JP-A-10-238349 (JP, A) JP-A-3-70812 (JP, A) JP-A-7-228951 (JP, A) 58-20350 (JP, A) JP-A-8-49542 (JP, A) JP-A-11-247659 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02B 19/00 -19/18 F02F 1/24 B22C 7/02

Claims (2)

(57) [Claims] A main combustion chamber (2) is provided in a cylinder (1),
Cavity (23) recessed in cylinder head (3)
(24) is fitted to form a sub-chamber (5), and its communication hole base (2) is formed.
The main combustion chamber (2) and the sub-chamber (5) are communicated by a communication hole (6) provided in 4), and the communication hole (6) is connected to one main communication hole (7) and a plurality of communication holes. A peripheral surface of the main communication hole (7) by arranging the sub communication holes (8) along the peripheral surface of the main communication hole (7). At the boundary between the main communication hole and the peripheral surface of the sub communication hole (8).
A ridge between the main and sub communication holes that protrudes sharply toward (7) (9)
In the diesel engine provided with a sub-chamber type combustion chamber, a casting using a wax model (33) is used for casting the communication hole base (24), and the main communication hole (7) is From the sub chamber (5) to the main combustion chamber
(2) The sub-communication hole (8) is formed in a tapered shape in which the passage cross-sectional area becomes larger as it goes to (2), and the sub-communication hole (8) is formed in a columnar shape. A tapered core (31) forming a hole (7) and at least one
The main communication hole (7) so that the cylindrical core (32) forming the sub communication hole (8) can be extracted in parallel in the same direction.
A communication hole base for a diesel engine having a sub-chamber type combustion chamber, wherein the posture of the at least one sub-communication hole (8) is set. 2. A diesel engine provided with a sub-chamber combustion chamber according to claim 1, wherein a center axis of at least two of the plurality of sub-communication holes (8) among the plurality of sub-communication holes (8). 28) are configured to be parallel to each other, and a tapered core (31) forming the main communication hole (7) is formed.
The main communication hole (7) and the at least two sub-communication holes (8) so that the core (32) forming the at least two sub-communication holes (8) can be extracted in parallel in the same direction. Communication hole
(8) A communication hole base for a diesel engine provided with a sub-chamber type combustion chamber, wherein the attitude is set as described above.