JPH08260974A - Indirect combustion chamber of diesel engine - Google Patents

Abstract

PURPOSE: To heighten a utilization factor of air in the inner end space of a main combustion chamber by forming a communicating hole for communicating a main combustion chamber with an auxiliary chamber by a single main communicating hole and plural auxiliary communicating holes, and forming the main communicating tale in such a manner that the passage sectional area is made smaller as it approaches the auxiliary chamber. CONSTITUTION: A communicating hole 6 for communicating a main combustion chamber 2 with an auxiliary chamber 5 is formed by a single main communicating hole 7 and plural auxiliary communicating holes 8. The respective auxiliary communicating holes 8 are formed on the peripheral surface of the main communicating hole 7 extending cover the whole length thereof. The passage sectional area of the main communicating hole 7 sandwiched between the auxiliary communicating holes 8 is made smaller as it approaches the auxiliary chamber 5. Thus, the compressed air is forced from the main combustion chamber 2 through the communicating hole 6 into the auxiliary chamber 5, and a forced stream 11 is formed in the auxiliary chamber 5, so that the air is favorably mixed with fuel 13 injected from a fuel injection nozzle 4. Some of fuel 13 is burnt in the auxiliary chamber 5, and expanded gas 37 containing unburnt fuel is blown off from the communicating hole 6 into the main combustion chamber 2 to be burnt.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art FIG. 3 shows a conventional technique for a sub-chamber type combustion chamber of a diesel engine. Like the present invention, it has the following basic structure. That is, FIG.
As shown in (G), the main combustion chamber 10 is provided in the cylinder 101.
2 is provided, and the fuel injection nozzle 1 is provided in the cylinder head 103.
A sub chamber 105 facing 04 is provided, the main combustion chamber 102 and the sub chamber 105 are communicated with each other through a communication hole 106, and the sub chamber 105 and the communication hole 106 are provided at positions eccentric from the cylinder center axis 126. Directing 106 toward the center of the cylinder 101, as shown in FIGS. 3 (A) to 3 (E), the communication hole 106 is composed of a single main communication hole 107 and a plurality of sub communication holes 108. The holes 108 are arranged along the circumferential surface of the main communication hole 107 along the entire length thereof, and as shown in FIG. 3 (E), viewed in a direction parallel to the cylinder center axis line 126, facing the both sides of the main communication hole center axis line 127. The sub-communication holes 108 are arranged.

In the auxiliary chamber type combustion chamber having such a basic structure, as shown in FIG. 3 (G), compressed air is pushed from the main combustion chamber 102 into the auxiliary chamber 105 through the communication hole 106 in the compression stroke. A forced flow 111 is formed in the sub chamber 105, the fuel 113 injected from the fuel injection nozzle 104 is mixed with the air in the sub chamber 105, a part of the fuel 113 is burned, and expansion including unburned fuel is performed. Gas 137 is communication hole 10
6 is blown into the main combustion chamber 102, mixed with the air in the main combustion chamber 102, and burned. As shown in FIG.
The compressed air passing through the communication hole 106 consists of a main compressed air flow 109 passing through the main communication hole 107 and a sub compressed air flow 110 passing through the sub communication hole 108.
A minute turbulent flow is generated in the sub chamber 105 due to mutual friction due to the speed difference between the sub compressed air flow 110 and the sub compressed air flow 110.

In the prior art shown in FIG. 3, the main communication hole 107 is provided.
Has a simple columnar shape, and means for positively accelerating the flow velocity of the main compressed air flow 109 is not adopted.

[0005]

In the prior art shown in FIG. 3, excellent combustion can be obtained by good combustion, but there are the following problems. That is, the main communication hole 107 has a mere columnar shape, and means for positively accelerating the flow velocity of the main compressed air flow 109 is not adopted.
Since the main compressed air flow 109 is not sufficiently accelerated in the inside and the speed difference between the main compressed air flow 109 and the sub compressed air flow 110 is insufficient, the amount of minute turbulence generated in the sub chamber 105 is small. The mixing performance of the fuel 113 and air in the sub chamber 105 was low. In addition, the expansion gas 137 causes the main communication hole center axis 12
7, the main combustion chamber 1 located on the opposite side of the communication hole 106 with the cylinder center axis 126 interposed therebetween.
The amount of expansion gas 137 reaching the rear end space 102a of 02 was insufficient, and the utilization rate of air in the rear end space 102a was low. Therefore, it is required to improve the combustion by improving the mixing performance of the fuel 113 and the air in the sub chamber 102 and increasing the air utilization rate in the rear end space 102a of the main combustion chamber 102. .

An object of the present invention is to provide a sub-chamber type combustion chamber of a diesel engine which can improve combustion.

[0007]

As shown in FIG. 1G, 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 is faced in 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,
The sub chamber 5 and the communication hole 6 are provided at positions eccentric from the cylinder center axis line 26, and the communication hole 6 is directed toward the center of the cylinder 1.
As illustrated in FIGS. 1A to 1E, the communication hole 6 is configured by a single main communication hole 7 and a plurality of sub communication holes 8, and each sub communication hole 8 is the entire length of the main communication hole 7. Along its circumference,
As illustrated in FIG. 1 (E), when viewed in a direction parallel to the cylinder center axis 26, a pair of sub-communication holes 8 are arranged on both sides of the main communication hole center axis 27. The feature of the room is as follows.

That is, as shown in FIGS. 1 (B) and 1 (D), the peripheral surface portion 7a of the main communication hole 7 which is sandwiched between the pair of auxiliary communication holes (8) and which is close to the cylinder center is provided in the auxiliary chamber 5. As it gets closer, the shape gradually becomes closer to the main communication hole central axis 27,
It is characterized in that the passage cross-sectional area of the main communication hole 7 gradually decreases as it approaches the sub chamber 5.

[0009]

According to the present invention, the main compressed air flow 9 is generated by the throttling effect of the peripheral surface portion 7a near the cylinder center in the main communication hole 7.
Is sufficiently accelerated, and the main compressed air flow 9 and the auxiliary compressed air flow 10
And the amount of minute turbulent flow generated in the sub-chamber 5 increases, and the mixing performance of the fuel 13 and air in the sub-chamber 5 increases. Further, since the expansion gas 37 blows out into the main combustion chamber 2 along the peripheral surface portion 7a near the cylinder center, away from the main communication hole center axis 27, the cylinder center axis 26
The expansion gas 37 smoothly reaches the rear end space 2a of the main combustion chamber 2 located on the side opposite to the communication hole 6 with the space between them, and the utilization rate of air in the rear end space 2a increases. Therefore, as compared with a case where the main communication hole 7 has a simple columnar shape, the mixing performance of the fuel 13 and the air in the sub chamber 5 is improved, and the air utilization rate in the inner end space 2a of the main combustion chamber 2 is increased. Increased, combustion is significantly improved.

[0010]

According to the present invention, the following effects can be obtained. Compared to the case where the main communication hole has a simple columnar shape, the mixing performance of fuel and air in the auxiliary chamber is improved, and the air utilization rate in the innermost space of the main combustion chamber is increased, which significantly improves combustion. . Therefore, it is possible to improve output, reduce fuel consumption, reduce harmful components of exhaust gas, and the like.

Since it suffices that the peripheral surface portion of the main communication hole near the center of the cylinder has a predetermined shape, it can be easily manufactured by a simple modification of the existing engine.

[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 sub combustion chamber type vertical diesel engine is used, and the configuration thereof is as follows. That is, FIG. 1 (G)
As shown in FIG. 3, a main combustion chamber 2 is provided in the cylinder 1, a sub chamber 5 facing the fuel injection nozzle 4 is provided in the cylinder head 3, and the main combustion chamber 2 and the sub chamber 5 are communicated with each other through a communication hole 6. Then, the sub chamber 5 and the communication hole 6 are provided at positions eccentric from the cylinder center axis line 26, and the communication hole 6 is directed toward the center portion of the cylinder 1 as shown in FIGS. 1 (A) to 1 (E). 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 arranged along the circumferential surface of the main communication hole 7 along its entire circumference.
As shown in (E), a pair of auxiliary communication holes 8 are arranged on both sides of the main communication hole center axis 27 when viewed in a direction parallel to the cylinder center axis 26.

Therefore, as shown in FIG. 1 (G), compressed air passes from the main combustion chamber 2 through the communication hole 6 to the sub chamber 5 in the compression stroke.
And a forced flow 11 is formed in the sub chamber 5,
The fuel 13 injected from the fuel injection nozzle 4 is mixed with the air in the sub chamber 5, a part of the fuel 13 burns, and the expansion gas 37 containing unburned fuel blows out from the communication hole 6 to the main combustion chamber 2. , Is mixed with the air in the main combustion chamber 2 and burns. FIG.
As shown in (F), the compressed air passing through the communication hole 6 is
It is composed of a main compressed air flow 9 passing through the main communication hole 7 and a sub-compressed air flow 10 passing through the sub-communication hole 8. Due to mutual friction due to the speed difference between the main compressed air flow 9 and the sub-compressed air flow 10, the sub chamber A small turbulent flow is generated within 5.

As shown in FIG. 1 (G), the main combustion chamber 2 is
It is provided between the cylinder head 3 and the piston head 21. The sub chamber 5 is as follows. That is, the hollow portion 23 is provided in the meat wall 22 of the cylinder head 3, and the communication hole cap 24 is fitted into the hollow portion 23 from the lower side thereof to form the hemispherical ceiling surface of the hollow portion 23 and the communication hole cap 24. The spherical sub-chamber 5 is formed by the hemispherical recessed portion 25 of FIG. The communication hole 6 is directed toward the spherical surface 5a of the sub chamber 5 near the cylinder peripheral wall and is inclined in the tangential direction thereof to form the sub chamber 5 as a vortex chamber. The fuel injection nozzle 4 is fixed to the wall 22 of the cylinder head 3. The communication hole 6 has a communication hole cap 24.
It is provided in.

In this embodiment, in order to improve combustion,
The following configuration was adopted. That is, FIG. 1 (B)
As shown in (D), the peripheral surface portion 7a of the main communication hole 7 which is sandwiched between the pair of sub communication holes 8 and which is close to the cylinder center gradually approaches the main communication hole central axis 27 as it approaches the sub chamber 5. Then, the passage cross-sectional area of the main communication hole 7 is gradually reduced toward the sub chamber 5.

Therefore, the main compressed air flow 9 is sufficiently accelerated by the throttling effect of the peripheral surface portion 7a near the center of the cylinder in the main communication hole 7, and the speed difference between the main compressed air flow 9 and the sub compressed air flow 10 is increased. Is increased, the amount of minute turbulence generated in the sub chamber 5 is increased, and the mixing performance of the fuel 13 and air in the sub chamber 5 is improved. Further, since the expansion gas 37 blows out into the main combustion chamber 2 along the peripheral surface portion 7a near the center of the cylinder so as to move away from the main communication hole center axis 27, the cylinder center axis 26 is sandwiched between the expansion gas 37 and the communication hole 6 on the opposite side. The expansion gas 37 smoothly reaches the rear end space 2a of the main combustion chamber 2 located, and the utilization rate of air in the rear end space 2a increases. Therefore, as compared with a case where the main communication hole 7 has a simple columnar shape, the mixing performance of the fuel 13 and the air in the sub chamber 5 is improved, and the air utilization rate in the inner end space 2a of the main combustion chamber 2 is increased. Increased, combustion is significantly improved.

The structure of the communication hole 6 is as follows. That is, as shown in FIG. 1B, the main communication hole central axis 27 is inclined at an elevation angle of 45 ° with respect to the bottom surface 28 of the communication hole cap 24. The basic shape of the main communication hole 7 is a cylinder, but FIG.
As shown in (B), (D), and (E), the peripheral surface portion 7a of the main communication hole 7 that is closer to the cylinder center has an inner diameter that gradually decreases as it approaches the sub chamber 5, and the main communication hole center axis 2
It is formed by a tapered surface approaching 7. Reference numeral 39 in FIG. 1 (B) is an outline of the cylindrical basic shape of the main communication hole 7 in the axial direction, and reference numeral 33 in FIG. 1 (D) is viewed in a direction parallel to the main communication hole central axis 27. In the case, it is a circumferential outline of the basic shape of the main communication hole 7.

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 whose inner diameter gradually decreases as it approaches the sub-chamber 5, and the communication hole 6 is formed. The cross-sectional area of the passage is gradually reduced as it approaches the sub chamber 5. Therefore, the compressed air passing through the communication hole 6 is gradually accelerated, the inflow flow 11 is sped up, and combustion is significantly improved. The tapered sub communication hole 8 can be easily formed by a taper reamer or the like.

In this embodiment, as shown in FIG. 1G, a fan-shaped expansion gas guide groove 35 is provided on the top surface of the piston head 21. The expansion gas guide groove 35, when viewed in a direction parallel to the cylinder center axis 26, has a starting end portion 36.
Is formed at a position where it overlaps with the communication hole 6, and the depth thereof gradually becomes shallower and the width thereof becomes wider as the distance from the starting end portion 36 to the cylinder central axis 26 side increases. Therefore, the expansion gas 37 blown into the main combustion chamber 2 from the communication hole 6 is throttled by raising the bottom of the expansion gas guide groove 35, speeded up, and smoothly guided to the rear end space 2a of the main combustion chamber 2. Also, the expansion gas guide groove 35 can be smoothly expanded in the width direction, and the mixing of the expansion gas 37 and the air in the main combustion chamber 2 becomes good.

The second embodiment shown in FIG. 2 is a modification of the first embodiment. In the first embodiment of FIG. 1, the peripheral surface portion 7a of the main communication hole 7 which is sandwiched between the pair of auxiliary communication holes 8 and which is close to the cylinder center is a series, whereas in the second embodiment, As shown in FIG. 2 (C), when viewed in a direction parallel to the cylinder center axis 26, the sub-communication hole 8 extends along the main communication hole center axis 27.
Is provided on the peripheral surface portion 7a near the cylinder center, and the peripheral surface portion 7a near the cylinder center is divided into two parts with this as a boundary. The other structure is the same as that of the first embodiment. In FIG. 2, the same elements as those in the first embodiment are designated by the same reference numerals.

The contents of the respective embodiments of the present invention are as described above, but the contents of the present invention are not limited to the respective embodiments. For example, the main communication hole 7 and the sub-communication hole 8 may have shapes other than those shown in each embodiment, and the basic shape of the main communication hole 7 may be an elliptic cylinder, a quadrangular prism, a triangular prism, or a triangular shape on the side of the auxiliary chamber 5. In addition, the main combustion chamber 2 side may be formed in a quadrangular deformed columnar shape, or the auxiliary communication hole 8 may be formed in a columnar shape, an elliptic cylinder, or a prismatic shape. Further, the auxiliary chamber 5 is not limited to the vortex chamber but may be a pre-combustion chamber.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a first embodiment of the present invention, and FIG.
1A is a vertical cross-sectional view of the communication hole cap, and FIG. 1B is FIG.
1 (A) is an enlarged view of a main part, FIG. 1 (C) is a perspective view of a communication hole, FIG. 1 (D) is a view of the communication hole in FIG.
(E) is a view of the communication hole in FIG. 1 (B) in the direction of arrow E, FIG. 1 (F)
Is an explanatory view of a compressed air flow, and FIG. 1 (G) is a vertical cross-sectional view of a sub-chamber combustion chamber.

FIG. 2 is a diagram for explaining the second embodiment, and FIG.
2C corresponds to FIG. 2C, and FIG. 2B corresponds to FIG.
FIG. 1C is a view corresponding to FIG.

FIG. 3 is a diagram illustrating a conventional technique, and FIG.
(A) Corresponding figure, FIG. 3 (B) is FIG.
1C is a view corresponding to FIG. 1C, FIG. 3D is a view corresponding to FIG. 1D, FIG. 3E is a view corresponding to FIG. 1E, and FIG. ) FIG. 3 (G) is a view corresponding to FIG. 1 (G).

[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 ... Cylinder center side peripheral surface portion, 8 ... Sub communication hole,
26 ... Cylinder center axis line, 27 ... Main communication hole center axis line.

Claims (1)

[Claims] 1. A main combustion chamber (2) is provided in a cylinder (1),
A sub-chamber (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 sub-chamber (5).
The sub chamber (5) and the communication hole (6) are provided at positions eccentric from the cylinder center axis (26) so that the communication hole (6) faces the center of the cylinder (1). The hole (6) is composed of a single main communication hole (7) and a plurality of sub communication holes (8).
Align (8) along the circumference of the main communication hole (7) along its circumference, and view it in a direction parallel to the cylinder center axis (26). In the sub-chamber combustion chamber of a diesel engine in which the holes (8) are arranged, the peripheral surface portion (7a) of the main communication hole (7) sandwiched between the pair of auxiliary communication holes (8) near the cylinder center is The shape is such that the main communication hole central axis (27) is gradually approached toward the chamber (5), and the passage cross-sectional area of the main communication hole (7) is gradually reduced toward the sub chamber (5). A sub-combustion type combustion chamber for diesel engines.