JPH08260977A - Indirect combustion chamber of diesel engine - Google Patents

Abstract

PURPOSE: To improve combustion by communicating a main combustion chamber with an auxiliary chamber by a communicating hole, leading out a guide groove from the communicating hole toward the central part of the main combustion chamber, and forming the guide groove in such a manner as to be gradually made shallower as it approaches the central part of the main combustion chamber and also gradually made wider. CONSTITUTION: A main combustion chamber 2 is provided in a cylinder 1, an auxiliary chamber 5 is provided in a cylinder head 3, and a communicating hole mouthpiece 24 of the auxiliary chamber 5 is fitted in an opening 3b of a cylinder head surface 3a facing to the main combustion chamber 2 to communicate the main combustion chamber 2 with the auxiliary chamber 5 by the communicating hole 6. In this case, a guide groove 15 is led out from the communicating hole 6 toward the central part of the main combustion chamber 2, and the guide groove 15 is recessed only in the bottom 28 of the communicating hole mouthpiece 25. The guide groove is formed in such a manner as to be gradually made shallower as it approaches the central part of the main combustion chamber 2 and also gradually made wider. Thus, forcing of a forced stream 11 and diffusion of expanded gas 37 are promoted so as to improve combustion.

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. 8 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, the main combustion chamber 102 is provided in the cylinder 101, and the sub chamber 105 in which the fuel injection nozzle 104 is faced in the cylinder head 103.
This sub chamber 105 is arranged at a position eccentric from the cylinder center axis line 126, and an opening 103b is provided on the cylinder head surface 103a facing the main combustion chamber 102.
The communication hole cap 124 of the sub-chamber 105 is fitted into 3b, and the communication hole 106 provided in the communication hole cap 124 is inserted into the main combustion chamber 102.
The main combustion chamber 102 and the auxiliary chamber 105 are communicated with each other through the communication hole 106 toward the center of the.

With such a structure, as shown in FIG. 8, compressed air is passed from the main combustion chamber 102 to the communication hole 1 in the compression stroke.
And is pushed into the sub-chamber 105 via 06, a pushing 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,
Part of the fuel 113 burns, and the expansion gas 137 containing unburned fuel blows out from the communication hole 106 into the main combustion chamber 102, is mixed with the air in the main combustion chamber 102, and burns.

In the prior art shown in FIG. 8, the main combustion chamber 102
The bottom surface 128 of the communication hole cap 124 facing the above is merely a flat surface, and the communication hole cap 124 does not have means for positively promoting functions such as pushing of the pushing flow 111 and diffusion of the expansion gas 137.

[0005]

In the prior art shown in FIG. 8, excellent combustion can be obtained by good combustion, but there are the following problems. That is, the bottom surface 128 of the communication hole mouthpiece 124 facing the main combustion chamber 102 is simply a flat surface, and the communication hole mouthpiece 124 positively promotes functions such as pushing of the pushing flow 111 and diffusion of the expansion gas 137. Therefore, there is a point that the combustion performance is insufficient, and it is demanded to improve the combustion by promoting the above function.

Prior to the present invention, the inventors of the present invention prototyped the one shown in FIG. In the preceding prototype, the guide groove 115 is led out from the communication hole 106 toward the center of the main combustion chamber 102 in the basic structure, and the guide groove 11 is formed.
Bottom surface 12 of the communication hole cap 124 facing the main combustion chamber 102
8 and the cylinder head surface 103a, the guide groove 115 has a shape that is gradually shallower and gradually widens as it approaches the center of the main combustion chamber 102. In FIG. 7, the same elements as those of the conventional technique are designated by the same reference numerals.

According to this preceding prototype, the guide groove 115
The compressed air is smoothly collected from the wide range on the central part side of the main combustion chamber 102 toward the communication hole 106, and from the communication hole 106 to the wide range on the central part side of the main combustion chamber 102. Since the expansion gas 137 is smoothly spread, the expansion gas 1 is pressed and the expansion gas 1 is pressed.
It was expected that the diffusion of 37 would be promoted and that the combustion would be significantly improved as compared with the case without the guide groove 115. However, in reality, contrary to that expectation, combustion did not improve sufficiently.

The cause is as follows. That is,
Since the inner bottom surface of the guide groove 115 retains the guiding function,
Although it is necessary to incline the bottom surface 128 of the communication hole cap 124 at an elevation angle 129 above a certain degree, the guide groove 1
Since 15 is formed to be relatively long over both the bottom surface 128 of the communication hole cap 124 and the cylinder head surface 103a, one of the factors is that the internal volume becomes too large and the reduction of the compression ratio exceeds the allowable range. Also,
Since the guide groove 115 is long, the communication hole 1 associated with its formation is formed.
The cut length 116 of the peripheral surface of 06 becomes long, and the pushing flow 111 and the expansion gas 137 are reduced in accordance with the deterioration of the straight guideability.
One of the factors is the decrease in the flow velocity. Further, due to the fitting error of the communication hole cap 124, the guide groove 11
One of the factors is that a step 118 is formed in the middle of the inner bottom surface of No. 5 and this becomes a flow resistance of the compressed air and the expansion gas 137.

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

[0010]

[Means for Solving the Problems]

(First Invention) As shown in FIG. 1 (E), the first invention provides a main combustion chamber 2 in a cylinder 1 and a sub chamber 5 facing a fuel injection nozzle 4 in a cylinder head 3. The sub chamber 5 is arranged at a position eccentric from the cylinder center axis 26, and the opening 3b is formed in the cylinder head surface 3a facing the main combustion chamber 2.
Is provided, the communication hole cap 24 of the sub chamber 5 is fitted into the opening 3b, and the communication hole 6 provided in the communication hole cap 24 is inserted into the main combustion chamber 2
In the sub-chamber type combustion chamber of the diesel engine in which the main combustion chamber 2 and the sub-chamber 5 are communicated with each other through the communication hole 6 toward the center of the sub-chamber, the following is characterized.

That is, as illustrated in FIG. 1, a guide groove 15 is led out from the communication hole 6 toward the center of the main combustion chamber 2, and the communication hole cap 24 facing the guide groove 15 to the main combustion chamber 2 is formed. Recessed only on the bottom surface 28 of the
It is characterized in that the width 15a becomes gradually shallower and gradually widens toward the center of the main combustion chamber 2.

(Second Invention) The second invention is shown in FIG.
As illustrated in (D), the first aspect of the invention is characterized as follows. That is, the side edges 15b of the guide groove 15 are curved so that the width of the width 15a of the guide groove 15 is gradually increased toward the center of the main combustion chamber 2.

[0013]

[Action]

(First Invention) According to the first invention, as illustrated in FIG. 1, the guide groove 15 guides the compressed air from the wide range on the central portion side of the main combustion chamber 2 toward the communication hole 6 smoothly. While being collected, the expanded gas 37 is smoothly spread from the communication hole 6 to a wide range on the central side of the main combustion chamber 2. Therefore, compared to the one without the guide groove 15,
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 15 is too long, combustion may not be improved due to a reduction in the compression ratio exceeding the allowable range or the like. However, since the guide groove 15 is formed to be relatively short, such a case may occur. No hindrance will occur.

The reason is as follows. That is, since the guide groove 15 is formed only on the bottom surface 28 of the communication hole cap 24, its length is relatively short and its internal volume can be small, so that the decrease in compression ratio can be suppressed. Further, the cut length 16 of the peripheral surface of the communication hole 6 due to the formation of the guide groove 15 can be short, and the decrease in the flow velocity of the pushing flow 11 and the expansion gas 37 due to the decrease in the straight guide property thereof can be suppressed to a small extent. Further, even if there is an error in fitting the communication hole cap 24, there is no room for forming a step in the inner bottom surface of the guide groove 15, so the flow resistance of the compressed air and the expansion gas 37 in the guide groove 15 can be kept small. You can

(Second Invention) In addition to the operation of the first invention, the second invention operates as follows. That is, as illustrated in FIG. 4, there are the following advantages as compared with the case where the both side edges 15b of the guide groove 15 are straightened so that the widths 15a of the guide grooves 15 spread at the same rate. That is,
As illustrated in FIG. 1, a wide skirt width of the guide groove 15b can be secured without increasing the internal volume of the guide groove 15 so much that compressed air is supplied from a wider range on the central side of the main combustion chamber 2. The expansion gas 3 can be collected and expanded toward a wider range on the central side of the main combustion chamber 2.
7 can be widened. 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 in the compression ratio, and the combustion is significantly improved.

[0017]

【The invention's effect】

(First Invention) The present invention has the following effects. As compared with the case without the guide groove, the pushing of the pushing flow and the diffusion of the expansion gas can be promoted, and the combustion is remarkably improved. Therefore, it is possible to improve output, reduce fuel consumption, reduce harmful components of exhaust gas, and the like.

Since the guide groove is a relatively short groove formed only on the bottom surface of the communicating hole die, it does not affect the improvement of combustion.

(Second invention) According to the second invention, the first invention
In addition to the effects of the invention, the following effects are achieved. Compared to the case where both sides of the guide groove are straightened so that the width of the width of the guide groove is the same, the reduction of the compression ratio is kept small and the pushing of the inflow flow and the diffusion of the expansion gas are further promoted. Combustion is more significantly improved.

[0020]

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 (E)
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 sub chamber 5 is arranged at a position eccentric from the cylinder center axis line 26. The cylinder head surface 3a facing the main combustion chamber 2.
Is provided with an opening 3b, the communication hole cap 24 of the sub chamber 5 is fitted into the opening 3b, and the communication hole 6 provided in the communication hole cap 24 is directed toward the center of the main combustion chamber 2 so that Combustion chamber 2
And the sub-chamber 5 are communicated with each other.

With this structure, as shown in FIG. 1 (E), 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 in the compression stroke. Flow 1
1 is formed and fuel 1 injected from the fuel injection nozzle 4
3 is mixed with the air in the sub chamber 5, a part of the fuel 13 is burned, and the expansion gas 37 containing unburned fuel is blown from the communication hole 6 to the main combustion chamber 2 and mixed with the air in the main combustion chamber 2. Is
Burn.

As shown in FIG. 1 (E), 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 configuration was adopted as follows. That is, as shown in FIG. 1, the guide groove 15 is led out from the communication hole 6 toward the center of the main combustion chamber 2, and only the bottom surface 28 of the communication hole cap 24 facing the main combustion chamber 2 is guided by the guide groove 15. Recessed, this guide groove 1
The shape of 5 is such that it gradually becomes shallower and the width 15a gradually expands from the communication hole 6 toward the center of the main combustion chamber 2.

According to this structure, the guide groove 15 guides the compressed air from the wide area on the central portion side of the main combustion chamber 2 toward the communication hole 6 smoothly, and the compressed air flows from the communication hole 6 to the main hole. The expansion gas 37 is smoothly spread over a wide range on the central side of the combustion chamber 2. Therefore, as compared with the case without the guide groove 15, 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 15 is too long, the combustion may not be improved due to a decrease in the compression ratio exceeding the allowable range or the like. However, since the guide groove 15 is formed to be relatively short, such a case may occur. No hindrance will occur. The reason is as follows. That is, the guide groove 15 is the communication hole base 2
Since it is formed only on the bottom surface 28 of No. 4, the length thereof is relatively short, the internal volume thereof can be small, and the reduction of the compression ratio can be suppressed. Further, the cutting length 16 of the peripheral surface of the communication hole 6 due to the formation of the guide groove 15 may be short,
It is possible to suppress the decrease in the flow velocity of the pushing flow 11 and the expansion gas 37 due to the decrease in the straight-line guiding property. Also,
Even if there is an error in fitting the communication hole cap 24, the guide groove 1
Since there is no room for forming a step in the middle of the inner bottom surface of 5, the flow resistance of the compressed air and the expansion gas 37 in the guide groove 15 can be suppressed small.

In this embodiment, as shown in FIGS. 1 (C) and 1 (D), as the center of the main combustion chamber 2 is approached, the width of the width 15a of the guide groove 15 is gradually increased to increase the guide rate. Both side edges 15b of the groove 15 are curved.
Therefore, as shown in FIG.
Compared to the case where the both side edges 15b of the guide groove 15 are straightened so that the rate of spread of a is the same, there are the following advantages. That is, as shown in FIG. 1, it is possible to secure a large skirt spreading width of the guide groove 15b without making the internal volume of the guide groove 15 so large that compressed air is compressed from a wider range on the central side of the main combustion chamber 2. The expansion gas 37 can be spread toward a wider range on the central side of the main combustion chamber 2 while collecting the expansion gas 37. 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 in the compression ratio, and the combustion is significantly improved.

As shown in FIGS. 1A to 1D and FIG. 2, the communication hole 6 is composed of a single main communication hole 7 and a plurality of auxiliary communication holes 8. By arranging each sub-communication hole 8 along the circumferential surface of the main communication hole 7 along the entire length thereof, the main communication hole 7 is formed at the boundary between the peripheral surface of the main communication hole 7 and the sub-communication hole 8.
By forming the ridges 9 between the main and sub communication holes that are sharply bulged toward each other, and adjoining the adjacent sub communication holes 8 to each other, the main communication is performed at the boundary between the peripheral surfaces of the sub communication holes 8. Sub-communicating hole projecting ridges 10 that are sharply raised toward the holes 7
Has been formed.

According to this structure, as shown in FIG. 3, near the end portion 9a of the protrusion 9 between the main and sub communication holes and on the side of the sub chamber 10a of the protrusion 10 between the sub communication holes. Then, a wake formed by the minute turbulent flow 12 is formed, and the fuel 13 injected from the fuel injection nozzle 4 is mixed well with the air in the sub chamber 5 by the minute turbulent flow 12, and combustion is improved.

The minute turbulent flow 12 formed by the ridges 9 between the main and sub communication holes is the air sandwiched between the translational flows 14 blown out from both sides of the sub chamber side end 9a of the ridges 9 between the main and sub communication holes. Caused by being entrained in each translational flow 14.
Minute turbulent flow 12 formed by the protrusion 10 between the sub-communication holes
The air sandwiched between the translational flows 17 blown out from both sides of the sub-chamber side end portion 10a of the protrusion 10 between the sub-communication holes is the translational flow 17
It is caused by being respectively involved in.

As shown in FIG. 1C, the end portion 10a of the inter-sub-communication hole projection 10 on the sub-chamber side is sharper than the end portion 9a of the main inter-sub-communication hole projection 9 on the sub-chamber side. Therefore, as shown in FIG.
As shown in, the distance 19 between the translational flows 17 on the side of the protrusion 10 between the sub-communication holes is equal to the translational flow 14 on the side of the protrusion 9 between the main and auxiliary communication holes.
It becomes shorter than the separation distance 20 between them, and each minute turbulence 12 is formed in the vicinity of each translational flow 17, and at the same time, a new minute turbulence 12 is generated due to friction between the adjacent minute turbulences 12. Therefore, the generation efficiency of the minute turbulent flow 12 by the protrusions 10 between the main and auxiliary communication holes is high, and the protrusions 9 between the main and auxiliary communication holes are high.
Compared with the only one, the mixing of the fuel 13 and the air in the sub chamber 5 becomes better, and the combustion is remarkably improved.

The main communication hole 7 has a cylindrical shape, and 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 cap 24. Also, FIG.
As shown in (A), 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 axis line 2
Assuming that 7 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, and the auxiliary communication hole 8 is arranged only on the peripheral surface 31 close to the cylinder center. There is.

As shown in FIG. 1C, when viewed in a direction parallel to the central axis 27 of the main communication hole, the edge of the sub communication hole 8 on the side of the sub chamber has a cylindrical basic shape of the main communication hole 7. Circumferential outline 33
It bulges outward from the circumferential outer shape line 33 with a larger curvature, and the sub-chamber side end 9a of the main / sub communication hole inter-projection ridge 9 and the sub-chamber side end 10a of the sub communication hole inter-projection ridge 10 are swelled. Circumferential outline 33
It's located above. Therefore, the sub-chamber-side end portion 10a of the inter-sub-communicating-hole protrusion 10 sandwiched between the curvature portions that are larger than the circumferential shape line 33 of the main communicating hole 7 is the main-sub-communicating-hole protrusion 9.
It becomes thinner than the end portion 9a on the sub chamber side.

As shown in FIGS. 1 (C) and 1 (D), five sub-communication holes 8 are provided in total, and the sub-communication hole projections are formed at the boundaries between the peripheral surfaces of all the adjacent sub-communication holes 8. Since 10 are formed, a total of four protrusions 10 between the sub-communication holes are formed.
A large amount of minute turbulence 12 is generated in each of the ridges 10 between the sub communication holes
Occurs and combustion is significantly improved. In order to secure a sufficient amount of minute turbulent flow 12, the number of the protrusions 10 between the sub-communication holes is preferably two or more, more preferably three or more, and four or more. Is most desirable.

As shown in FIG. 1 (C), the peripheral surface of the sub-communication hole 8 is formed as a taper surface that gradually shrinks toward the sub-chamber 5,
Since the passage cross-sectional area of the communication hole 6 is gradually reduced as it approaches the sub chamber 5, the compressed air passing through the communication hole 6 is gradually accelerated. Therefore, each of the translational flows 14 and 17 shown in FIG.
Generated more, the inrush flow 11 is also faster,
Combustion is significantly improved. The tapered sub communication hole 8 can be easily formed by a taper reamer or the like.

As shown in FIG. 1 (E), 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 is formed in the cylinder center axis 2
When viewed in a direction parallel to 6, the starting end portion 36 is formed at a position overlapping the communication hole 6, and as the starting end portion 36 moves away from the starting end portion 36 toward the cylinder center axis 26 side, the depth thereof gradually decreases and the width thereof increases. Is designed to spread. 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 to increase the speed, and is smoothly guided to the rear end space 2a of the main combustion chamber 2 located on the opposite side of the communication hole 6 with the cylinder center axis 26 interposed therebetween. At the same time, the expansion gas guide groove 35 can be smoothly expanded in the width direction, so that the expansion gas 37 and the air in the main combustion chamber 2 can be mixed well.

The second embodiment shown in FIG. 4 is a modification of the first embodiment. In the first embodiment, as shown in FIGS. 1C and 1D, the width of the width 15a of the guide groove 15 is gradually increased as the distance from the communication hole 6 to the center of the main combustion chamber 2 is increased. Further, both side edges 15b of the guide groove 15 are curved. On the other hand, in the second embodiment of FIG. 4, the guide groove 1
The side edges 15b of the guide groove 15 were straightened so that the widths of the widths 15a of 5 became the same.

The third embodiment of FIG. 5 and the fourth embodiment of FIG. 6 are also modifications of the first embodiment. In the first embodiment, FIG.
As shown in (C) and (D), five sub-communication holes 8 are provided,
These are arranged only on the peripheral surface 31 of the main communication hole 7 near the cylinder center. On the other hand, in the third embodiment of FIG. 5, the pair of auxiliary communication holes 8 are arranged only on the peripheral surface 32 of the main communication hole 7 near the cylinder peripheral wall. Further, in the fourth embodiment of FIG. 6, two pairs of sub-communication holes 8 are arranged on the peripheral surface 31 of the main communication hole 7 near the center of the cylinder and the peripheral surface 32 of the peripheral wall near the cylinder.
Other configurations of the second to fourth embodiments shown in FIGS. 4 to 6 are the same as those of the first embodiment. In the figure, the same elements as those in the first embodiment are designated by the same reference numerals.

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 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 rectangular deformed column, 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 a cylinder, an elliptic cylinder, or a prism. Further, the plurality of sub-communication holes 8 may be arranged on both the peripheral surface 31 near the cylinder center and the peripheral surface 32 near the cylinder peripheral wall of the main communication hole 7 shown in FIG. 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.
1A is an enlarged view of a main part, FIG. 1C is a view in the direction C of FIG. 1B, FIG. 1D is a view in the direction D of FIG. 1B, and FIG.
(E) is a vertical cross-sectional view of the sub-chamber combustion chamber.

FIG. 2 is a perspective view of a communication hole and a guide groove according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating the principle of generation of minute turbulence according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a second embodiment of the present invention, and FIG.
1A is a view corresponding to FIG. 1B, FIG. 4B is a view corresponding to FIG. 1C, and FIG. 4C is a view corresponding to FIG.

5 is a diagram illustrating a third embodiment of the present invention, and FIG.
1A is a view corresponding to FIG. 1B, FIG. 5B is a view corresponding to FIG. 1C, and FIG. 5C is a view corresponding to FIG.

FIG. 6 is a diagram illustrating a fourth embodiment of the present invention, and FIG.
1A is a view corresponding to FIG. 1B, FIG. 6B is a view corresponding to FIG. 1C, and FIG. 6C is a view corresponding to FIG.

7A and 7B are diagrams illustrating a preceding prototype example, FIG. 7A is a vertical cross-sectional view of a main part, and FIG. 7B is a vertical cross-sectional view of a sub-chamber combustion chamber.

FIG. 8 is a vertical sectional view of a sub-chamber type combustion chamber according to a conventional technique.

[Explanation of symbols]

1 ... Cylinder, 2 ... Main combustion chamber, 3 ... Cylinder head, 3
a ... Cylinder head surface, 3b ... Opening, 4 ... Fuel injection nozzle, 5 ... Sub chamber, 6 ... Communication hole, 15 ... Guide groove, 15a ...
Width, 15b ... Side edge, 24 ... Communication hole mouthpiece, 26 ... Cylinder center axis line, 28 ... Bottom surface.

Claims (2)

[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 the sub-chamber (5) is connected to the cylinder center axis (2).
6) is provided at a position eccentric to the main combustion chamber (2), and an opening (3b) is provided on the cylinder head surface (3a) facing the main combustion chamber (2)
The communication hole cap (24) of the sub chamber (5) is fitted into (3b), and the communication hole (6) provided in the communication hole cap (24) is directed toward the center of the main combustion chamber (2). Main combustion chamber (2) and sub chamber (5) with holes (6)
In a sub-chamber combustion chamber of a diesel engine in which the guide groove (15) is communicated with the guide groove (15) from the communication hole (6) toward the center of the main combustion chamber (2). The main combustion chamber
Only the bottom surface (28) of the communication hole cap (24) facing the (2) is provided with a recess, and the guide groove (15) becomes gradually shallower and gradually becomes wider (15a) as it approaches the center of the main combustion chamber (2). ) Has a shape that expands. A subcombustion combustion chamber for a diesel engine. 2. The auxiliary chamber type combustion chamber for a diesel engine according to claim 1, wherein the width of the width (15a) of the guide groove (15) gradually increases toward the center of the main combustion chamber (2). Both sides of the guide groove (15) to increase
A sub-chamber combustion chamber of a diesel engine, characterized in that (15b) is curved.