JP3295268B2 - 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, the main combustion chamber 102 and the sub chamber 105 are communicated with each other through the communication hole 106, and the sub chamber 105 and the communication hole 106 are provided at a position eccentric from the cylinder center axis 126. The communication hole 106 is formed by a single main communication hole 107 and a plurality of sub-communication holes 108 as shown in FIGS. 5A to 5E. The hole 108 extends along the peripheral surface of the main communication hole 107 over the entire length thereof, and as shown in FIG. 5 (E), when viewed in a direction parallel to the cylinder center axis 126, a pair of sides are formed on both sides of the main communication hole center axis 127. Are provided.

According to such a structure, as shown in FIG. 5 (G), compressed air is pushed into the sub chamber 105 from the main combustion chamber 102 through the communication hole 106 in the compression stroke,
A forced flow 111 is formed in the fuel injection nozzle 10.
The fuel 113 injected from 4 is satisfactorily mixed with the air in the sub-chamber 105 by the pushing flow 111. FIG. 5 (F)
As shown in the figure, the pushing flow 111 is composed of a main pushing flow 114 pushed from the main communication hole 107 and a sub-communication hole 108.
And the main pushing flow 114 is pushed into the central part of the sub chamber 105,
The sub-pushing flow 115 is pushed into both sides of the sub-chamber 105.

In the prior art shown in FIG. 5, as shown in FIG. 5B, an imaginary plane including a main communication hole center axis 127 and being parallel to a cylinder center axis 126 is assumed, and is orthogonal to this imaginary plane. The main communication hole center axis 12
7 is assumed to be a boundary line, and the peripheral surface of the main communication hole 107 is divided into a peripheral surface 131 near the cylinder center and a peripheral surface 132 near the cylinder peripheral wall at this boundary line, and the sub communication hole is provided only on the peripheral surface 131 near the cylinder center. Only one pair 108 is provided.

[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 compressed air passing through the main communication hole 107 receives the flow resistance from both the peripheral surface 131 near the cylinder center and the peripheral surface 132 near the cylinder peripheral wall, but the flow resistance greatly differs depending on the presence or absence of the sub communication hole 108. Due to the imbalance, the straightness of the main pushing flow 114 was reduced and the flow velocity was reduced, and the air flow in the central part of the sub chamber 105 was insufficient. Further, since only one sub-pressing flow 115 is supplied to both sides of the sub-chamber 105, the flow of air at both sides of the sub-chamber 105 is insufficient. Therefore, there is a demand for improving the combustion by promoting the air flow in the sub chamber 105.

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,
The sub chamber 5 and the communication hole 6 are provided at a position eccentric from the cylinder center axis 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 includes a single main communication hole 7 and a plurality of sub-communication holes 8, and each sub-communication hole 8 has the entire length of the main communication hole 7. Over its circumference,
As illustrated in FIG. 1 (E), a sub-chamber type combustion of a diesel engine in which a pair of sub-communication holes 8 are arranged on both sides of a main communication hole central axis 27 when viewed in a direction parallel to the cylinder central axis 26. The room is characterized as follows.

That is, as exemplified in FIG.
Including the main communication hole center axis 27 and the cylinder center axis 2
Assuming an imaginary plane parallel to 6 and looking in a direction orthogonal to this imaginary plane, assuming the main communication hole center axis 27 as a boundary line,
At this boundary line, the peripheral surface of the main communication hole 7 is divided into a peripheral surface 31 near the cylinder center and a peripheral surface 32 near the cylinder peripheral wall, and the peripheral surface 31 near the cylinder center and the peripheral surface 32 near the cylinder peripheral wall are described above. A pair of sub communication holes 8 are provided , respectively ,
Guide groove 18 toward the center of main combustion chamber 2
The guide groove 18 faces the main combustion chamber 2 and the communication hole base 2
4 is recessed only in the bottom surface 28, and this guide groove 18
As it approaches the center of the main combustion chamber 2 from the hole 6, gradually
The width 18a is formed so as to be shallow and gradually widen .

[0009]

The compressed air passing through the main communication hole receives flow resistance from both the peripheral surface 31 close to the cylinder center and the peripheral surface 32 close to the cylinder peripheral wall. Because of the provision, the flow resistance becomes more uniform, the straightness of the main pushing flow 14 is high, the flow velocity thereof is also high, and the flow of air in the central portion of the sub chamber 5 is promoted. Further, as shown in FIG. 1 (F), at least two sub-indentation flows 15 are supplied to both sides of the sub-chamber 5, respectively. A small turbulent flow is formed at both sides of the sub-chamber 5, and the flow of air at both sides of the sub-chamber 5 is also promoted. For this reason, compared with the case where only one pair of the sub communication holes 8 are provided only in the peripheral surface 31 of the main communication hole 7 near the cylinder center, the mixing of the fuel 13 and the air in the sub chamber 5 becomes better, and the combustion is remarkably improved. You.

[0010]

According to the present invention, the following effects can be obtained. Compared to the case where only one pair of sub-communication holes are provided on the peripheral surface of the main communication hole near the center of the cylinder, the mixing of fuel and air in the sub-chamber is better, and the combustion is significantly improved. Therefore, it is possible to improve output, reduce fuel consumption, reduce harmful exhaust components, and the like.

Since it is only necessary to form at least two pairs of auxiliary communication holes, the engine can be easily manufactured by a simple modification of an existing engine.

[0012]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a view for explaining a first embodiment of the present invention. In this embodiment, a vertical diesel engine of a sub-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. The sub-chamber 5 and the communication hole 6 are provided at positions eccentric from the cylinder center axis 26, and the communication hole 6 is directed toward the center of the cylinder 1, and as shown in FIGS. 1 is composed of 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.
As shown in (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.

According to such a configuration, as shown in FIG. 1 (G), compressed air is pushed from the main combustion chamber 2 through the communication hole 6 into the sub-chamber 5 during the compression stroke, and into the sub-chamber 5. Stream 1
1 is formed and the fuel 1 injected from the fuel injection nozzle 4
3 is mixed well with the air in the sub-chamber 5 by the forced flow 11. As shown in FIG.
Is a main pushing flow 14 pushed from the main communication hole 7,
The main pushing flow 14 is pushed into the central portion of the sub chamber 5, and the sub pushing flow 15 is pushed into both sides of the sub chamber 5.

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. 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 has a communication hole base 24.
It is provided in.

In this embodiment, in order to improve combustion,
The following configuration was adopted. That is, as shown in FIG. 1 (B), 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 27 is a boundary line, the peripheral surface of the main communication hole 7 is divided into a peripheral surface 31 closer to the cylinder center and a peripheral surface 32 closer to the cylinder peripheral wall at this boundary line, and the peripheral surface 31 closer to the cylinder center and the peripheral surface closer to the cylinder peripheral wall. The pair of sub-communication holes 8 described above are provided on both of the peripheral surfaces 32.

According to such a configuration, the compressed air passing through the main communication hole 7 receives the flow resistance from both the peripheral surface 31 near the cylinder center and the peripheral surface 32 near the cylinder peripheral wall. Since each of the pair of sub-communication holes 8 is provided, the flow resistances thereof are more uniform, the straightness of the main pushing flow 14 is high, the flow velocity thereof is high, and the flow of air in the central portion of the sub-chamber 5 is reduced. Promoted. Further, as shown in FIG. 1 (F), at least two sub-indentation flows 15 are supplied to both sides of the sub-chamber 5, respectively. A small turbulent flow is formed at both sides of the sub-chamber 5, and the flow of air at both sides of the sub-chamber 5 is also promoted. For this reason, the peripheral surface 31 of the main communication hole 7 near the cylinder center.
Only the sub-communication hole 8 is provided only in
The mixing of the fuel 13 and the air at the step is improved, and the 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 center axis 27 is inclined at an elevation angle of 45 ° with respect to the bottom surface 28 of the communication hole base 24. The main communication hole 7 is cylindrical. FIG. 1 (C) ~
As shown in (E), the sub-communication hole 8 is formed with a tapered surface whose inner diameter gradually decreases as approaching the sub-chamber 5, and gradually increases as the passage cross-sectional area of the communication hole 6 approaches the sub-chamber 5. It is made to shrink. For this reason, the pushing flow 11 is also accelerated, 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 in the top surface of the piston head 21. When viewed in a direction parallel to the cylinder center axis 26, the inflation gas guide groove 35 has its starting end 3.
6 is formed at a position overlapping with the communication hole 6, and as the distance from the starting end 36 toward the cylinder center axis line 26 decreases, the depth gradually decreases and the width gradually increases. For this reason, the expansion gas 37 blown out from the communication hole 6 into the main combustion chamber 2 is throttled by raising the bottom of the expansion gas guide groove 35, and the speed is increased, so that the cylinder center axis 2 is increased.
Main combustion chamber 2 located on the opposite side of communication hole 6 with
And smoothly expanded in the width direction of the expansion gas guide groove 35, so that the mixture of the expansion gas 37 and air in the main combustion chamber 2 is improved.

In this embodiment, as shown in FIGS. 1 and 2, a guide groove 18 is led out from the communication hole 6 toward the center of the main combustion chamber 2, and the guide groove 18 faces the main combustion chamber 2. The guide groove 18 is formed so as to be gradually shallower and the width 18a gradually increases as it approaches the center of the main combustion chamber 2 from the communication hole 6. According to such a configuration, the compressed air is smoothly collected from the wide range on the central part side of the main combustion chamber 2 toward the communication hole 6 by the guide of the guide groove 18, and the main combustion chamber 2 is The inflation gas 37 is smoothly spread over a wide range on the center side of the inflatable gas. For this reason, as compared with the case where the guide groove 18 is not provided, the pushing of the pushing flow 11 and the diffusion of the expansion gas 37 are promoted, and the combustion is remarkably improved.

If the guide groove 18 is too long, combustion may not be improved due to reasons such as a decrease in compression ratio exceeding an allowable range.
Since it is formed only on the bottom surface 28 and is relatively short, such trouble does not occur. The reason is as follows. That is, since the guide groove 18 is formed only on the bottom surface 28 of the communication hole base 24, its length is relatively short, its internal volume is small, and a decrease in compression ratio can be suppressed. In addition, the cut length 19 (see FIG. 1 (B)) of the peripheral surface of the communication hole 6 due to the formation of the guide groove 18 may be short, and the pushing flow 11 and the inflation gas 3 due to the decrease in the linear guideability.
7, the decrease in flow velocity can be kept small. Also, even if there is an error in fitting into the communication hole base 24, the guide groove 18
Since there is no room for forming a step in the middle of the inner bottom surface, the flow resistance of the compressed air or the expansion gas 37 in the guide groove 18 can be reduced.

In this embodiment, as shown in FIG. 2, both side edges 18b of the guide groove 18 are so arranged that the width of the width 18a of the guide groove 18 gradually increases toward the center of the main combustion chamber 2. It is curved. For this reason, there is the following advantage as compared with the case where both side edges 18b of the guide groove 18 are straightened so that the width of the width 18a of the guide groove 18 is the same. That is, the guide groove 18b can be formed without increasing the internal volume of the guide groove 18 too much.
And the compressed air can be collected from a wider range on the central portion side of the main combustion chamber 2, and the expansion gas 37 is directed toward a wider range on the central portion side of the main combustion chamber 2. Can be spread. For this reason, it is possible to further promote the pushing of the pushing flow 11 and the diffusion of the expanding gas 37 while keeping the decrease in the compression ratio small,
Combustion is more significantly improved.

The second embodiment shown in FIG. 3 is a modification of the first embodiment. In the first embodiment, the main communication hole 7 has a simple cylindrical shape, whereas in the second embodiment, FIG.
(A) to (C), the peripheral surface 3 near the cylinder center.
A deflection protrusion 9 protruding into the main communication hole 7 is provided on a peripheral surface portion of the main communication hole 7 interposed between the pair of sub communication holes 8 provided in 1, and the deflection protrusion 9 is connected to the main communication hole 7. The only difference is that the hole 7 penetrates into the cylindrical basic shape, and the other parts are the same as those of the first embodiment. In the figure, the same elements as those of the first embodiment are denoted by the same reference numerals. Reference numeral 33 in FIG. 3 (B) denotes a circumferential outer shape line of the basic shape of the main communication hole 7 when viewed in a direction parallel to the main communication hole center axis 27, and reference numeral 3 in FIG.
Reference numeral 4 denotes a basic outline of an opening of the main communication hole 7 on the main combustion chamber side when viewed in a direction parallel to the cylinder center axis 26, and reference numeral 38 denotes a basic outline of an opening of the main communication hole 7 on the sub chamber side.

As shown in FIGS. 3 (A) to 3 (C), the deflecting ridge 9 has a middle-to-high shape having a top 9a in the width direction center of the peripheral surface portion of the main communication hole 7, and FIG. As shown in (E), the width 9b is gradually widened toward the sub-chamber 5. According to such a configuration, FIG.
As shown in the figure, the main pushing flow 14 passing through the main communication hole 7
Is deflected to both sides by the guidance of the deflection ridge 9, and is supplied to both sides of the sub chamber 5 as a deflected flow 16. For this reason,
On both sides of the sub-chamber 5, a large amount of a part of the main pushing flow 14 is supplied as a deflected flow 16 in addition to the two sub-pressing flows 15 pushed from the sub-communication holes 8. The flow of air in the part is promoted and compared to the case without the deflecting ridge 9,
The mixing of the fuel 13 and the air in the sub-chamber 5 is improved, and the combustion is significantly improved.

As shown in FIGS. 3A to 3C, the deflecting ridge 9 is formed by a smooth middle-high curved surface connecting the pair of sub-communication holes 8, and as shown in FIG. The top 9a is shaped so as to approach the central axis 27 of the main communication hole as approaching the sub chamber 5.

The third embodiment shown in FIG. 4 is also a modification of the first embodiment. In the first embodiment, as shown in FIGS. 1C and 1E, the width of the peripheral surface portion 7a sandwiched between the pair of sub-communication holes 8 of the peripheral surface 31 near the cylinder center is constant. In the third embodiment, the width of the peripheral surface portion 7a is
The only difference from the first embodiment is that it gradually decreases as approaching. In the figure, the same elements as those of the first embodiment are denoted by the same reference numerals. According to such a configuration, the expansion gases 37 that have passed through the pair of sub-communication holes 8 of the peripheral surface 31 near the center of the cylinder collide with each other in the main combustion chamber 2, and are forced to move in the lateral direction by the repulsive force. And the diffusion efficiency is increased, and the combustion is improved.

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. In addition, sub-room 5
It 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).
1 is a sectional view taken along line FF of FIG. 1 (G), and FIG. 1 (G) is a longitudinal sectional view of a sub-chamber type combustion chamber.

2A and 2B are diagrams illustrating a communication hole base used in the sub-chamber type combustion chamber of FIG. 1; FIG. 2A is a perspective view of a communication hole and a guide groove, and FIG. (D) Equivalent figure, FIG. 2 (C)
FIG. 2 is a view corresponding to FIG.

FIG. 3 is a diagram for explaining a second embodiment of the present invention.
(A) is a diagram corresponding to FIG. 1 (C), FIG. 3 (B) is a diagram corresponding to FIG. 1 (D), FIG. 3 (C) is a diagram corresponding to FIG. 1 (E), and FIG. FIG. 3E is a sectional view of a main part of FIG. 3B.

FIG. 4 is a diagram for explaining a third 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, 8 ... Sub communication hole, 26 ... Cylinder center axis, 27 ... Main communication hole center axis, 31 ... Circumferential surface near cylinder center, 32 …
The peripheral surface near the cylinder peripheral wall.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-276211 (JP, A) JP-A-6-257440 (JP, A) JP-A-7-11957 (JP, A) Japanese Utility Model Showa 53- 57109 (JP, U) JP 35-17054 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02B 19/00-19/18

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).
The sub-chamber (5) and the communication hole (6) are provided at a position eccentric from the cylinder center axis (26), and the communication hole (6) is directed toward 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).
(8) is arranged along the peripheral surface over the entire length of the main communication hole (7), and when viewed in a direction parallel to the cylinder center axis (26), a pair of sub-communications are provided on both sides of the main communication hole center axis (27). In a sub-combustion chamber of a diesel engine, in which a hole (8) is arranged, a main communication hole center axis (27) and a cylinder center axis are included.
Assuming an imaginary plane parallel to (26), and looking in a direction perpendicular to this imaginary plane, assuming the central axis (27) of the main communication hole as a boundary line, the boundary line defines the periphery of the main communication hole (7). The surface is divided into a peripheral surface closer to the cylinder center (31) and a peripheral surface closer to the cylinder peripheral wall (32), and both the peripheral surface closer to the cylinder center (31) and the peripheral surface closer to the cylinder peripheral wall (32), Sub communication holes (8) are provided , and guide grooves are formed from the communication holes (6) toward the center of the main combustion chamber (2).
(18) is derived, and this guide groove (18) is inserted into the main combustion chamber (2).
Only the bottom surface (28) of the communicating hole base (24) facing
Guide groove (18) extends from communication hole (6) to the center of main combustion chamber (2).
Section, shallower and progressively wider (18
A sub-combustion chamber for a diesel engine, characterized in that a) is formed so as to expand .