JPH094457A - Combustion chamber of 3-valve overhead valve diesel engine - Google Patents

Abstract

PURPOSE: To improve exhaustion efficiency by providing an exhaustion recessed part in a piston head formed so as to spread including an exhaust valve and two intake valves when a piston is seen from a cylinder head on a plane. CONSTITUTION: A roughly triangular shape exhaustion recessed part 8, a roughly fan shaped guiding groove 25 and one valve recess 19 are formed in a piston head 7, the exhaustion recessed part 8 and the guiding groove 25 are arranged opposite to each other so as to communicate these with each other and the valve recess 19 is laid over the exhaustion recessed part 8. Two valve recesses 17 and 18 are formed for a combined use by the exhaustion recessed part 8 and this exhaustion recessed part 8 is formed to be triangular spreading so as to include an exhaust valve 5 and two intake valves 4 and 4. The guiding groove 25 is formed with a fan shaped pivot (a) facing the jetting hole 15 of an overcurrent room 11 from the lower side and the tip part 25b of the guiding groove 25 spreading toward the exhaustion recessed part 8 and the exhaustion recessed part 8 is set with its capacity center displaced from the center of a piston 6 to the exhaust valve 5 side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion chamber of a three-valve overhead valve diesel engine equipped with two intake valves and one exhaust valve, and enhances exhaust efficiency to increase engine charging efficiency. Provided is one that can prevent overheating of the exhaust wall peripheral wall.

[0002]

BACKGROUND OF THE INVENTION Generally, a diesel engine may be provided with two intake valves in order to perform intake efficiently, but the exhaust valve is (1) a sub-chamber diesel engine with a sub-chamber mouthpiece. Since it fits on the lower surface of the cylinder head, there is not enough space for two exhaust valves. (2) In a four-valve engine provided with two exhaust valves in addition to two intake valves, the structure of the cylinder head becomes complicated. (3) When two exhaust valves are provided, the partition wall between the exhaust valves is easily overheated and has a thin wall. Due to the above reasons, the number is limited to one and may be configured as a three-valve overhead valve diesel engine.

The present invention is directed to the combustion chamber of this three-valve diesel engine, and its basic structure is as shown in FIGS. 1 to 6, in which a cylinder head 2 is assembled above a cylinder 1 and the cylinder head 2 is attached to the cylinder head 2. A type in which two intake valves 4 and one exhaust valve 5 are provided, and the piston head 7 of the piston 6 fitted in the cylinder 1 faces the intake valve 4, the exhaust valve 5 and the cylinder head lower surface 3. Is.

[0004]

2. Description of the Related Art As a conventional technique of this type, two intake valves 4 and 4 are provided in one half of the cylinder head 2 around the combustion chamber, and the diameter of the intake valve 4 is slightly larger than the other half. The exhaust valve 5 is generally provided.

[0005]

In the above prior art, since there is only one exhaust valve 5 above all, some of the exhaust gas tends to stay in the combustion chamber, which is not sufficient in terms of smooth exhaust of the exhaust gas. .

If smooth exhaust is not performed, intake air cannot smoothly flow into the combustion chamber, and the charging efficiency of the engine, fuel consumption, or output is adversely affected. Further, when the high-heat exhaust gas stays, the inclined peripheral wall portion of the exhaust port is likely to be overheated, which may cause cracks or thermal strain. The present invention is a three-valve overhead valve diesel engine,
The technical issue is to improve exhaust efficiency.

[0007]

Means for achieving the above object will be described below with reference to FIGS. 1 to 6 showing an embodiment. That is, the first aspect of the present invention is, in the combustion chamber of the three-valve overhead valve diesel engine having the basic structure, the exhaust recess 8 in either the piston head 7 or the cylinder head lower surface 3.
When the piston 6 is viewed from the cylinder head 2 in a plan view, the exhaust concave portion 8 has the exhaust valve 5 and the two intake valves 4 and 4
It is characterized by spreading to include the whole.

The present invention 2 is characterized in that, in the above-mentioned invention 1, the exhaust recess 8 is formed so that the exhaust valve 5 side is deepest.

The present invention 3 is characterized in that, in the above-mentioned present invention 2, the exhaust concave portion 8 is formed so as to become deeper continuously as it approaches the exhaust valve 5.

A fourth aspect of the present invention is the above-described first to third aspects, in which the cylinder head 2 is provided with the swirl chamber 11, the piston head 7 is formed with a guide groove 25, and the guide groove 25 is formed in the injection hole of the swirl chamber 11. When the piston 6 is viewed from below from the bottom of the cylinder head 15 and the cylinder head 2 is viewed from above, the exhaust recess 8 is formed into the guide groove 2.
It is characterized in that it is configured to communicate with 5.

The overhead valve diesel engine E of the present inventions 1 to 3 includes both a direct injection type and a sub chamber type. Invention 4 above
Then, the exhaust recess 8 provided on the piston head 7 may be communicated with the guide groove 25, or the exhaust recess 8 provided on the lower surface 3 of the cylinder head may be communicated with the guide groove 25 in a plan view.

[0012]

[Action]

(1) In the present invention 1, the exhaust recess 8 is provided in either the piston head 7 or the cylinder head lower surface 3, and the exhaust recess 8 includes the exhaust valve 5 and the two intake valves 4.4 as a whole. Since it expands to include the exhaust gas, the exhaust gas is likely to concentrate around the exhaust valve 5 in the exhaust stroke. Moreover, since the distance between the exhaust port and the piston head 7 is greatly expanded by the amount corresponding to the depression of the exhaust concave portion 8, the exhaust gas is smoothly discharged from the exhaust port.

(2) In the second and third aspects of the present invention, the exhaust valve 5 side of the exhaust recess 8 is formed deep and the volume center of the exhaust recess 8 is deviated to the exhaust valve 5 side. Exhaust gas is likely to be concentrated around the valve 5, and when the exhaust valve 5 is continuously formed deep as in the third embodiment of the invention, the continuous surface acts to concentrate the exhaust gas around the exhaust valve 5. Can be promoted more.

(3) In the fourth aspect of the present invention, since the guide groove 25 is formed in the piston head 7, the intake air of the main combustion chamber is guided by the ascending guide groove 25 of the piston head 7 in the compression stroke and the injection hole 15 is formed. Smoothly flows into the swirl chamber 11, and the swirl is promoted in the swirl chamber 11.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a plan view of a piston head of a three-valve vertical overhead valve diesel engine showing Embodiment 1, and FIG. 2 is I of FIG.
-I line sectional view, FIG. 3 is a II-II line sectional view of FIG. 1, and FIG. 4 is a perspective view of the same piston head.

As shown in FIG. 2, the cylinder head 2 is assembled above the cylinder 1 of the overhead valve subchamber diesel engine E, and the piston 6 is fitted in the cylinder 1 so as to be vertically movable. The sub chamber mouthpiece 10 is engaged with the cylinder head lower surface 3 of the cylinder head 2 facing the piston 6, the fuel injection nozzle 12 is thrust into the swirl chamber 11 in the subchamber mouthpiece 10 from above, and the swirl chamber 11 is ejected. Main combustion chamber 16 through hole 15
Communicate with Further, two intake ports 13 and one exhaust port 14 are opened in the cylinder head 2, and two intake valves 4.4 are attached to the intake ports 13 and 13.
A single exhaust valve 5 is provided to each of the above-mentioned valves so that the piston head 7 faces the intake valve 4, the exhaust valve 5 and the cylinder head lower surface 3 to form a three-valve overhead valve diesel engine. The diameter of the exhaust valve 5 is slightly larger than that of the intake valve 4.

As shown in FIGS. 1 to 4, the piston head 7 has a substantially triangular exhaust recess 8 and a substantially fan-shaped guide groove 2.
5 and one valve recess 19 are formed, and the exhaust recess 8 and the guide groove 25 are arranged to face each other so that they communicate with each other and the valve recess 19 overlaps the exhaust recess 8. Further, the two valve recesses 17 and 18 are also used as the exhaust recesses 8. In this case, the valve recess 19 is arranged to face the exhaust valve 5 on the cylinder head 2 side, and the valve recesses 17 and 18 are arranged to face the intake valves 4 and 4, respectively.

As shown in FIGS. 1 and 4, when the piston 6 is viewed from the cylinder head 2 in a plan view, the exhaust recess 8 is formed.
Is formed in a triangular shape that extends so as to include the exhaust valve 5 and the two intake valves 4 and 4 as a whole. Further, in the guide groove 25, the fan-shaped kaname 25a is formed in the injection hole 1 of the swirl chamber 11.
5, the tip portion 25b of the guide groove 25 spreads toward the exhaust recess 8 and smoothly communicates with the exhaust recess 8 while partially overlapping the valve recess 19 and the valve recess 18.

As shown in FIGS. 3 and 4, the exhaust concave portion 8 has a deepest smooth surface on the exhaust valve 5 side (that is, the portion of the valve recess 19), and the intake valve 4 side (that is, the valve recess). 17 and 18) are formed to have a shallow smooth surface, and the volume center of the exhaust recess 8 is deviated from the center of the piston 6 toward the exhaust valve 5 side. However, it is also possible to form the exhaust concave portion 8 into a continuous inclined surface that becomes deeper as it approaches the exhaust valve 5 and becomes shallower as it approaches the intake valve 4.

Further, as shown in FIGS. 2 and 4, the fan-shaped guide groove 25 has a nozzle hole 15 of the swirl chamber 11 in a longitudinal sectional view.
Is formed as a continuous inclined surface that becomes deeper as it gets closer to. The injection hole 15 of the guide groove 25
The depth on the side is set to be substantially the same as the depth on the exhaust valve 5 side of the exhaust concave portion 8.

Therefore, the function of the combustion chamber of the three-valve vertical subchamber diesel engine of the first embodiment will be described. First, the piston head 7 is provided with a substantially circular exhaust recess 8 and the exhaust valve 5 side of the exhaust recess 8 is formed deepest, so exhaust is concentrated around the exhaust valve 5 in the exhaust stroke. Easy to do. Secondly, since the distance between the exhaust port 14 and the piston head 7 can be increased by the amount of the recessed portion 8 for exhaust, the exhaust gas can be discharged smoothly. Thirdly, since the center of volume of the exhaust concave portion 8 is deviated from the center of the piston 6 toward the exhaust valve 5, the exhaust is more likely to be concentrated around the exhaust valve 5 in the exhaust stroke.

As a result, in the exhaust stroke, the exhaust gas is effectively concentrated around the exhaust valve 5 and discharged smoothly, so that the exhaust efficiency is improved. Therefore, the exhaust gas does not stay in the combustion chamber and the intake air flows in smoothly, so that the charging efficiency, fuel consumption, or output of the diesel engine E is improved. Further, since high-heat exhaust gas does not stay, it is possible to prevent overheating of the inclined peripheral wall portion of the exhaust port 14 and prevent cracks and thermal distortion.

On the other hand, since the guide groove 25 is formed in the piston head 7, the intake air of the main combustion chamber 16 is guided by the ascending guide groove 25 of the piston head 7 from the injection hole 15 to the swirl chamber 11 in the compression stroke. Since the air flows smoothly into the swirl chamber 11, the generation of swirl in the swirl chamber 11 is promoted, the mixing performance of air and fuel is enhanced, and the fuel efficiency and the output are further improved.

FIG. 5 shows a second embodiment of the present invention. Unlike the first embodiment in which the exhaust recess 8 is formed deepest on the exhaust valve 5 side, the exhaust recess extends over the exhaust valve 5 side and the intake valve 4 side. 8 is formed to have the same constant depth.

FIG. 6 shows a third embodiment of the present invention in which only the exhaust recess 8 is provided in the piston head 7 and the guide groove 25 is omitted. The exhaust recessed portion 8 is formed in a continuous inclined surface, which becomes deeper as it approaches the exhaust valve 5 and becomes shallower as it approaches the intake valve 4 (however, the exhaust valve 5
It is also possible to form a constant depth toward the intake valve 4 from).

In the third embodiment, since the guide groove 25 is not formed in the piston head 7 and the shape of the piston head 7 can be simplified, the piston head 7 can be implemented at a lower cost than the first or second embodiment. Further, the diesel engine to which the third embodiment is applied is not limited to the swirl chamber type diesel engine, but may be applied to a pre-combustion chamber type or other sub chamber type diesel engine.

As described above, according to the present invention, the exhaust recess 8 is provided.
In a plan view, one exhaust valve 5 and two intake valves 4
Since it is widened so as to include the whole of 4, the structure is not limited to the structure in which the exhaust concave portion 8 is arranged in the piston head 7 as in the above-described first to third embodiments. You can place it. Further, the present invention (specifically, the present inventions 1 to 3) characterized in that the exhaust concave portion 8 is provided can be applied regardless of a direct injection diesel engine or a sub-chamber diesel engine. Furthermore, the present inventions 1 to 4 are not limited to the vertical overhead valve diesel engine, and are also applied to a horizontal overhead valve diesel engine in which the cylinder bores are arranged laterally.

[0028]

EFFECTS OF THE INVENTION (1) According to the first aspect of the present invention, since the exhaust recess is formed, exhaust gas is effectively concentrated and smoothly discharged around the exhaust valve in the exhaust stroke, so that exhaust efficiency is improved. Therefore, the exhaust gas does not stay in the combustion chamber and the intake air flows in smoothly, so that the charging efficiency of the engine, the fuel consumption, or the output is improved. Further, since the high-heat exhaust gas does not stay, it is possible to prevent overheating of the inclined peripheral wall portion of the exhaust port and prevent cracks and thermal distortion.

(2) In the second and third aspects of the present invention, the exhaust valve side of the exhaust recess is deeply formed so that the concentration and discharge of exhaust gas around the exhaust valve can be promoted more smoothly. The effect is further improved.

(3) In the fourth aspect of the present invention, in the compression stroke, the intake air smoothly flows into the swirl chamber through the nozzle holes while being guided by the guide groove from the main combustion chamber, so that the swirl flow is promoted in the swirl chamber. From this aspect, the mixing performance of air and fuel is improved.
The fuel efficiency and output of the engine are improved.

[Brief description of drawings]

FIG. 1 is a plan view of a piston head of a three-valve vertical overhead valve diesel engine showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line I-I of FIG.

FIG. 3 is a sectional view taken along line II-II of FIG.

FIG. 4 is a perspective view of the piston head.

FIG. 5 is a vertical sectional view of a piston head according to a second embodiment of the present invention.

FIG. 6 is a view corresponding to FIG. 1 showing a third embodiment of the present invention.

[Explanation of symbols]

1 ... Cylinder, 2 ... Cylinder head, 3 ... Cylinder head lower surface, 4 ... Intake valve, 5 ... Exhaust valve, 6 ... Piston, 7 ...
Piston head, 8 ... Exhaust recess, 11 ... Vortex chamber, 15
... Nozzle holes in swirl chamber, 25 ... Guide groove, E ... 3-valve overhead valve diesel engine.

Claims (4)

[Claims] 1. A cylinder head above the cylinder (1).
Assemble (2) and install two intake valves on the cylinder head (2).
(4.4) and one exhaust valve (5) are provided, and the piston head (7) of the piston (6) fitted inside the cylinder (1) is an intake valve.
(4), in the combustion chamber of a three-valve overhead valve diesel engine facing the exhaust valve (5) and the lower surface (3) of the cylinder head, exhaust gas to either the piston head (7) or the lower surface (3) of the cylinder head. When the piston (6) is viewed in plan from the cylinder head (2) by providing the concave portion (8) for the
The exhaust recess (8) has an exhaust valve (5) and two intake valves (4.
A combustion chamber of a three-valve overhead valve diesel engine, which is characterized by expanding so as to include the whole of 4). 2. The combustion chamber of a three-valve overhead valve diesel engine according to claim 1, wherein the exhaust recess (8) is formed so that the exhaust valve (5) side is deepest. 3. The combustion of a three-valve overhead valve diesel engine according to claim 2, wherein the exhaust recess (8) is formed so as to become deeper continuously as it approaches the exhaust valve (5). Room. 4. A swirl chamber (11) is provided in a cylinder head (2), a guide groove (25) is formed in a piston head (7), and the guide groove (25) is formed into a nozzle hole (15) of the swirl chamber (11). ) From below and when the piston (6) is viewed from the cylinder head (2) in a plan view,
The combustion chamber of a three-valve overhead valve diesel engine according to any one of claims 1 to 3, characterized in that the exhaust recess (8) is configured to communicate with the guide groove (25).