JPH08260979A - Indirect combustion chamber of diesel engine - Google Patents

Abstract

PURPOSE: To improve combustion 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, dividing the peripheral surface of the main communicating hole into the peripheral surface to the side of the center of a cylinder and the peripheral surface to the side of the peripheral wall of the cylinder, and disposing the paired auxiliary communicating holes on the respective peripheral surfaces. CONSTITUTION: A communicating hole 6 for communicating a main combustion chamber 2 in a cylinder 1 with an auxiliary chamber 5 to which a fuel injection nozzle 4 faces in a cylinder head 3 is formed by a single main communicating hole 7 and plural auxiliary communicating holes 8, the respective auxiliary communicating holes 8 are laid along the peripheral surface of the main communicating hole 8 extending over the whole length thereof, and the paired auxiliary communicating holes 8 are disposed on both sides of the central axis of the main communicating hole 7. In this case, the central axis of the main communicating hole 7 is taken to be a boundary line, the peripheral surface of the main communicating hole 7 is divided into the peripheral surface to the side of the center of the cylinder and the peripheral surface to the side of the peripheral wall of the cylinder, and the paired auxiliary communicating holes 8 are respectively provided on both of the peripheral surfaces. Thus, mixture of fuel 13 and air in the auxiliary chamber 5 can be made better so as to improve the combustibility.

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. 5 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. 5A to 5E, 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 is performed. The holes 108 are arranged along the peripheral surface of the main communication hole 107 along the entire length thereof, and as shown in FIG. 5E, when viewed in a direction parallel to the cylinder center axis line 126, the holes 108 face both sides of the main communication hole center axis line 127. The sub-communication holes 108 are arranged.

According to this structure, as shown in FIG. 5G, compressed air is pushed from the main combustion chamber 102 into the auxiliary chamber 105 through the communication hole 106 in the compression stroke, and the auxiliary chamber 105 is reached.
A forced flow 111 is formed in the fuel injection nozzle 10
The fuel 113 injected from No. 4 is mixed well with the air in the sub chamber 105 by the rush flow 111. Figure 5 (F)
As shown in FIG. 3, the pushing flow 111 is a main pushing flow 114 pushed from the main communicating hole 107 and the sub communicating hole 108.
And a sub-inflow flow 115 pushed in from the main chamber.
The sub push flow 115 is pushed into both side portions of the sub chamber 105.

In the prior art shown in FIG. 5, as illustrated in FIG. 5B, an imaginary plane including the center axis 127 of the main communication hole and parallel to the cylinder center axis 126 is assumed and 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 only the peripheral surface 131 near the cylinder center is the auxiliary communication hole. Only one pair 108 is provided.

[0005]

In the prior art shown in FIG. 5, excellent combustion 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 flow resistance from both the peripheral surface 131 of the cylinder center and the peripheral surface 132 of the cylinder peripheral wall, but the flow resistance greatly differs depending on the presence or absence of the auxiliary communication hole 108. However, due to the imbalance, the straight flowability of the main inflow flow 114 was reduced and the flow velocity decreased, and the air flow in the central portion of the sub chamber 105 was insufficient. Further, since only one line of the sub-pushing flow 115 is supplied to both sides of the sub chamber 105, the air flow in both sides of the sub chamber 105 was insufficient. Therefore, it is required to improve the combustion by promoting the air flow in the sub chamber 105.

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 illustrated in FIG. 1 (B),
Main communication hole center axis 27 is included, and cylinder center axis 2
Assuming a virtual plane parallel to 6 and looking in a direction orthogonal to this virtual plane, the main communication hole center axis 27 is assumed to be a boundary line,
The boundary surface divides the peripheral surface of the main communication hole 7 into a peripheral surface 31 close to the cylinder center and a peripheral surface 32 close to the cylinder peripheral wall, and is described above on both the peripheral surface 31 close to the cylinder center and the peripheral surface 32 close to the cylinder peripheral wall. A pair of sub-communication holes 8 are provided respectively.

[0009]

The compressed air passing through the main communication hole 7 receives flow resistance from both the peripheral surface 31 near the center of the cylinder and the peripheral surface 32 near the peripheral wall of the cylinder. Since they are provided, these flow resistances become more uniform, the straightness of the main pushing flow 14 is high, the flow velocity 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-inward flows 15 are supplied to both side portions of the sub-chamber 5, and both side portions of the sub-chamber 5 are caused by friction and collision due to mutual contact. A minute turbulent flow is formed in the side wall of the sub chamber 5, and the air flow in both side portions of the sub chamber 5 is promoted. Therefore, as compared with a case where only one pair of auxiliary communication holes 8 are provided only on the peripheral surface 31 of the main communication hole 7 close to the center of the cylinder, the mixing of the fuel 13 and air in the auxiliary chamber 5 is improved and combustion is significantly improved. It

[0010]

According to the present invention, the following effects can be obtained. Compared to a case where only one pair of sub-communication holes is provided only 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 becomes better, and combustion is significantly improved. Therefore, it is possible to improve output, reduce fuel consumption, reduce harmful components of exhaust gas, and the like.

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

[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.

According to this structure, as shown in FIG. 1G, compressed air is pushed from the main combustion chamber 2 into the sub chamber 5 through the communication hole 6 and into the sub chamber 5 during the compression stroke. Flow 1
1 is formed and fuel 1 injected from the fuel injection nozzle 4
3 is mixed well with the air in the subchamber 5 by the forced flow 11. As shown in FIG. 1 (F), the inflow flow 11
Is a main push flow 14 pushed from the main communication hole 7,
It is composed of a sub pushing flow 15 pushed from the sub communication hole 8, the main pushing flow 14 is pushed into the central part of the sub chamber 5, and the sub pushing flow 15 is pushed to both sides of the sub chamber 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, as shown in FIG. 1 (B), an imaginary plane that includes the main communication hole center axis line 27 and is parallel to the cylinder center axis line 26 is assumed, and when viewed in a direction orthogonal to this imaginary plane, the main communication hole center line 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 close to the cylinder center and a peripheral surface 32 close to the cylinder peripheral wall at this boundary line. The above-described pair of sub-communication holes 8 are provided on both of the peripheral surfaces 32, respectively.

According to this structure, the compressed air passing through the main communicating hole 7 receives flow resistance from both the peripheral surface 31 of the cylinder center and the peripheral surface 32 of the cylinder peripheral wall. Since the pair of sub-communication holes 8 are provided respectively, the flow resistances of these are made more uniform, the straightness of the main pushing flow 14 is high, the flow velocity is also high, and the flow of air in the central portion of the sub-chamber 5 is high. Be promoted. Further, as shown in FIG. 1 (F), at least two sub-inward flows 15 are supplied to both side portions of the sub-chamber 5, and both side portions of the sub-chamber 5 are caused by friction and collision due to mutual contact. A minute turbulent flow is formed in the side wall of the sub chamber 5, and the air flow in both side portions of the sub chamber 5 is promoted. Therefore, the peripheral surface 31 of the main communication hole 7 near the cylinder center
In comparison with the case where only one pair of sub-communication holes 8 is provided in the sub chamber 5,
The mixing of the fuel 13 and the air in the above is improved, and the combustion is remarkably 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 main communication hole 7 has a cylindrical shape. FIG. 1 (C)-
As shown in (E), the sub-communication hole 8 is formed with a tapered surface whose inner diameter gradually decreases as it approaches the sub chamber 5, and the passage cross-sectional area of the communication hole 6 gradually becomes closer to the sub chamber 5. It is designed to shrink. For this reason, the inflow flow 11 is also accelerated 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 its starting end portion 3
6 is formed at a position where it overlaps with the communication hole 6, and the depth thereof gradually decreases and the width thereof gradually increases as the distance from the starting end portion 36 to the cylinder center axis 26 side increases. Therefore, the expansion gas 37 blown 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 speeded up, so that the cylinder center axis 2
The main combustion chamber 2 located on the opposite side of the communication hole 6 with 6 interposed therebetween.
In addition to being smoothly guided to the innermost space 2a, the expansion gas guide groove 35 is also smoothly expanded in the width direction, so that the expansion gas 37 and the air in the main combustion chamber 2 are mixed well.

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 recessed in the surface and has a shape in which the width 18 a gradually becomes shallower and gradually widens as the guide groove 18 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 portion side of the main combustion chamber 2 toward the communication hole 6 by the guide groove 18, and at the same time, the main combustion chamber 2 is discharged from the communication hole 6. The expansion gas 37 is smoothly spread over a wide range on the central side of the. Therefore, as compared with the case without the guide groove 18, 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, the combustion may not be improved due to the reason that the reduction of the compression ratio exceeds the allowable range. However, the guide groove 18 has a communicating hole cap 24.
Since it is formed only on the bottom surface 28 of the base plate and is relatively short, such an obstacle 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 cap 24, the length thereof is relatively short and the internal volume thereof can be small, so that the reduction of the compression ratio can be suppressed. In addition, the cut length 19 (see FIG. 1B) 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 expansion gas 3 due to the deterioration of the straight-line guiding property thereof.
It is possible to suppress the decrease in the flow velocity of No. 7 to be small. In addition, even if there is a fitting error in the communication hole cap 24, the guide groove 18
Since there is no room for a step to be formed in the middle of the inner bottom surface, the flow resistance of the compressed air and the expansion gas 37 in the guide groove 18 can be suppressed to be small.

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's curved. Therefore, there are the following advantages as compared with the case where the both side edges 18b of the guide groove 18 are straightened so that the widths 18a of the guide grooves 18 spread at the same rate. That is, without increasing the internal volume of the guide groove 18 too much, the guide groove 18b
The width of the bottom of the main combustion chamber 2 can be secured to be large, compressed air can be collected from a wider range on the central side of the main combustion chamber 2, and the expansion gas 37 can be directed toward a wider range on the central side of the main combustion chamber 2. Can be expanded. Therefore, it is possible to further promote the pushing of the pushing flow 11 and the diffusion of the expansion gas 37 while suppressing the decrease of the compression ratio.
The combustion is improved significantly.

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 columnar shape, whereas in the second embodiment, as shown in FIG.
As shown in (A) to (C), the peripheral surface 3 near the center of the cylinder
1 is provided with a deflecting ridge 9 protruding toward the inside of the main communicating hole 7 in the peripheral surface portion of the main communicating hole 7 sandwiched between the pair of sub communicating holes 8 and the main communicating hole 9 is connected to the main communicating hole 7. The only difference is that the hole 7 is inserted into the cylindrical basic shape, and the other points are the same as in the first embodiment. In the figure, the same elements as those in the first embodiment are designated by the same reference numerals. Reference numeral 33 in FIG. 3 (B) is a circumferential outline of the basic shape of the main communication hole 7 when viewed in a direction parallel to the main communication hole central axis 27, reference numeral 3 in FIG. 3 (C).
Reference numeral 4 is a basic outline of the main communication hole 7 on the side of the main combustion chamber when viewed in a direction parallel to the cylinder center axis 26, and reference numeral 38 is a basic outline of the opening on the auxiliary chamber side of the main communication hole 7.

As shown in FIGS. 3 (A) to 3 (C), the deflecting ridge 9 has a middle-height shape in which the central portion in the width direction of the peripheral surface portion of the main communicating hole 7 is the apex portion 9a. 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 main pushing flow 14 passing through the main communication hole 7
Is partially deflected to the both sides by the guide of the deflecting ridge 9, and the deflected flow 16 is supplied to the both side portions of the sub chamber 5. For this reason,
To both sides of the sub-chamber 5, a large amount of a part of the main push-in flow 14 is supplied as a deflected flow 16 in addition to each of the two sub-injection flows 15 pushed from the sub-communication holes 8, and both sides of the sub-chamber 5 are supplied. The flow of air in the part is promoted, and compared with the one without the ridge 9 for deflection,
The mixing of the fuel 13 and the air in the sub chamber 5 is improved, and the combustion is remarkably improved.

As shown in FIGS. 3 (A) to 3 (C), the ridge 9 for deflection is formed by a smooth curved surface having a middle height which connects the pair of auxiliary communication holes 8, and as shown in FIG. 3 (B). The top portion 9a is shaped so as to approach the main communication hole central axis 27 as it approaches 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. 1 (C) and 1 (E), the peripheral surface portion 7a sandwiched between the pair of auxiliary communication holes 8 on the peripheral surface 31 near the center of the cylinder has a constant width. In the third embodiment, the width of the peripheral surface portion 7a is the main combustion chamber 2
The first embodiment differs from the first embodiment only in that it becomes smaller gradually as it approaches. In the figure, the same elements as those in the first embodiment are designated by the same reference numerals. According to such a configuration, the expanded gases 37 that have passed through the pair of auxiliary communication holes 8 on the peripheral surface 31 near the center of the cylinder collide with each other in the main combustion chamber 2, and the repulsive forces force the expansion gases 37 in the sideward direction. The diffusion efficiency is increased, and the combustion is improved.

The contents of the embodiments of the present invention are as described above, but the contents of the present invention are not limited to the above embodiments. For example, the main communication hole 7 and the sub communication hole 8 may have shapes other than those shown in the respective embodiments, and the main communication hole 7 has an elliptic cylinder shape, a quadrangular prism shape, a triangular prism shape, and the side of the auxiliary chamber 5 has a triangular shape for main combustion. Room 2
The side may be in the shape of a quadrangular prism, the peripheral surface of the main communication hole 7 may be a tapered surface that shrinks toward the sub chamber 5, or the sub communication hole 8 may be cylindrical, elliptic, or prismatic. In addition, sub-chamber 5
The pre-combustion chamber is not limited to the vortex chamber and 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)
1G is a sectional view taken along the line FF of FIG. 1G, and FIG. 1G is a longitudinal sectional view of the auxiliary chamber combustion chamber.

2A and 2B are views for explaining a communication hole cap used in the auxiliary chamber type combustion chamber of FIG. 1, FIG. 2A is a perspective view of the communication hole and a guide groove, and FIG. 2B is a view of the communication hole cap. (D) Corresponding diagram, FIG. 2 (C)
1 is a view corresponding to FIG. 1 (E) of the communication hole cap.

FIG. 3 is a diagram illustrating a second embodiment of the present invention, and FIG.
1A corresponds to FIG. 1C, FIG. 3B corresponds to FIG. 1D, FIG. 3C corresponds to FIG. 1E, and FIG. ) FIG. 3E is a cross-sectional view of the main part of FIG. 3B.

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

FIG. 5 is a diagram illustrating a conventional technique, and FIG.
(A) equivalent figure, FIG. 5 (B) is FIG. 1 (B) equivalent figure, FIG.
1C is equivalent to FIG. 5D, FIG. 5D is equivalent to FIG. 1D, FIG. 5E is equivalent to FIG. 1E, and FIG. ) FIG. 5 (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, 8 ... Sub communication hole, 26 ... Cylinder center axis, 27 ... Main communication hole center axis, 31 ... Cylinder center peripheral surface, 32 …
Circumferential surface near the cylinder wall.

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 a sub-chamber combustion chamber of a diesel engine in which the hole (8) is arranged, the main communication hole central axis (27) is included and the cylinder central axis is included.
Assuming an imaginary plane parallel to (26) and looking in a direction orthogonal to this imaginary plane, the central axis of the main communication hole (27) is assumed to be the boundary line, and this boundary line defines the circumference of the main communication hole (7). The surface is divided into a peripheral surface (31) close to the cylinder center and a peripheral surface (32) close to the cylinder peripheral wall, and both the peripheral surface (31) close to the cylinder center and the peripheral surface (32) close to the cylinder peripheral wall are paired with each other as described above. A sub-chamber combustion chamber for a diesel engine, characterized in that each sub-communications hole (8) is provided.