JPH0776530B2 - Whirlpool combustion chamber of diesel engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a vortex chamber combustion chamber of a diesel engine, which can effectively improve the air utilization rate even during a period in which a piston passes near the top dead center. I will provide a.

<Prior Art> The basic structure of a vortex chamber type combustion chamber of a diesel engine which is the subject of the present invention is, as shown in FIG. 3, a vortex chamber via an injection port 2 at an eccentric portion of a main combustion chamber 1 of a diesel engine E. 3 and the axial center 4 of the injection port 2 extends from the vortex chamber 3 to the main combustion chamber 1
It is configured such that the combustion airflow is blown from the injection port 2 to the piston head 8 located near the top dead center so as to be inclined so as to approach the central portion of the main combustion chamber 1 as it approaches.

As a conventional technique of this type, one in which the injection port 2 is simply formed in a cylindrical shape, or in order to improve the dispersion performance of the combustion air flow in the main combustion chamber 1 and increase the air utilization rate, Japanese Patent Publication No. 57-59410 is disclosed. As shown in Fig. 2, a pair of sideways is attached to both wing portions of the round hole to form a downwardly widening taper-shaped injection port 2, and the expansion angle to the left and right is expanded from the injection port 2 toward the flat piston head which is compressed and raised. There is a thing that has a combustion airflow ejected.

<Problems of Prior Art> In general, in order to increase the efficiency of vortex flow to the vortex chamber, it is necessary to make the volume of the vortex chamber 3 as large as possible and the main combustion chamber 1 as small as possible. Is becoming very narrow.

Therefore, in the above-described conventional technique, since the injection port 2 seems to be blocked by the flat piston head during the period in which the piston passes near the upper point, the injection port 2 is formed in a simple tubular shape, Even when it is formed in a spread taper shape, the combustion airflow expanding in the vortex chamber 3 receives a large flow resistance at the outlet of the injection port 2 and causes a pressure loss.

In addition, since the combustion airflow is subject to flow resistance, there is a delay in the propagation of fire and the combustion performance is reduced.

<Prior Invention> Therefore, the present applicant previously proposed the invention shown in FIG. 10 for the purpose of reducing the flow resistance of the combustion air flow even during the period in which the piston passes near the top dead center.

That is, in the above-mentioned prior invention, a fan-shaped recess 7 is formed in the piston head 8 such that the fan-shaped recess 7 is widened to the left and right as it goes from the starting end 10 to the tip 12, and the starting end 10 of the recess 7 is opened in the vortex chamber 31. It was made to face.

In the above-mentioned proposal, since the injection port 2 faces the starting end portion 10 of the recess 7 formed in the piston head 8 and is open even during the period when the piston (6) passes near the top dead center, The combustion airflow ejected into the main combustion chamber 1 enters the recess 7 without being subjected to flow resistance, and is smoothly guided toward the tip portion 12 thereof.

Therefore, the flow resistance of the combustion air flow is significantly reduced, the pressure loss is reduced, and the delay of fire propagation is eliminated.

However, the combustion airflow entering the recess 7 spreads to the left and right according to the opening angle of the recess, but is restrained by the left and right side surfaces 53 of the recess 7 and tries to spread only inside this. However, there is a possibility that the mixing with the air in the main combustion chamber 1 may be restricted.

The present invention aims to further improve the air utilization rate in the main combustion chamber.

<Means for Solving the Problems> Means for achieving the above objects will be described below with reference to FIGS. 1 to 9 corresponding to the embodiments.

That is, according to the present invention, when the piston 6 is near the top dead center, the recess 7 for guiding the combustion airflow ejected from the injection port 2 in the main combustion chamber 1 is provided in the piston head 8, and from the start end portion 10 to the tip end portion.
It is formed so as to spread laterally as it goes to 12, and the starting end portion 10 of the recess 7 is made to face the injection port 2 so as to spread over the left and right side surfaces 53, 53 of the recess 7.

<Operation> The combustion airflow ejected from the nozzle 2 to the starting end 10 of the recess 7 spreads left and right in the recess 7 toward the tip 12, but the left and right side surfaces 53, 53 of the recess 7 are upward. Since it is formed in a divergent shape and is open to the outside of the recess 7, so that the air outside the recess 7 can flow from the left and right side surfaces 53, 53 to the inside of the recess 7 due to the directional combustion air flow. And is spread to the entire main combustion chamber 1 from the tip portion 12 while promoting the mixing with the combustion air flow.

<Effects of the Invention> First, in the present invention, by forming a recess in the piston head, the flow resistance of the combustion airflow can be reduced, pressure loss can be eliminated, and fire propagation can be speeded up.

In addition, since the left and right side surfaces of the recess are spread upward, the air outside the recess is easily drawn in on the left and right side surfaces, the mixing of the combustion air flow and the air is promoted, and the air utilization rate can be improved.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings.

1 is a plan view of a piston head showing the first embodiment, FIG. 2 is a right side view in vertical section around the piston head, FIG. 3 is a right side view in vertical section of a vertical diesel engine, and FIG. In the schematic diagram, a cylinder 15 is formed in the center of a cylinder block 14 of a diesel engine E, and a piston 6 is fitted in the cylinder 15 so as to be vertically slidable.

The cylinder head 16 is assembled above the cylinder block 14, and the fuel injection space 19 is bored in the inner wall of the cylinder head 16 facing the main combustion chamber 1 in the latter half of the cylinder head 16, and the fuel injection space 19 is half opened from the lower opening edge. The split injection chamber member 20 is fitted to form the vortex chamber 3 by the upper hemisphere portion of the fuel injection space 19 and the lower hemisphere portion of the injection chamber member 20.

A nozzle fitting insertion hole 21 is provided so as to extend from the upper end of the latter half of the cylinder head 16 to the fuel injection space 19, and a fuel injection nozzle 22 is fitted and inserted into the fitting insertion hole 21, and the tip end injection port portion 23 is inserted into the vortex chamber 3. To face.

The injection port 2 is directed to the injection chamber member 20 in a rearward upward slanted form, that is, the axial center 4 of the injection port 2 is oriented so as to be closer to the central portion of the main combustion chamber 1 from the swirl chamber 3 to the main combustion chamber 1.

As shown in FIG. 11, the injection port 2 has a round hole 24, which serves as a main ejection passage for the combustion airflow, formed in the center thereof, and a side passage 25 is formed over the left and right side surfaces 5 slightly closer to the front. It is constructed by forming a boundary in a mine shape.

With respect to the axis of the round hole 24, each axis of the side road 25 is inclined so as to expand to the left and right as it goes downward (that is, as the passage cross-sectional area of the side road 25 approaches the main combustion chamber 1, (It is configured to increase in the left-right direction) so that the combustion airflow ejected from the injection port 2 to the main combustion chamber 1 spreads to the left and right sides.

In addition to the above-described embodiment, as the tapered injection port 2 for spreading the combustion airflow to the left and right, for example, as shown in FIG. It is good, but in the present invention, it is also possible to use the injection port 2 which is simply formed in a cylindrical shape as shown in FIG.

On the other hand, a fan-shaped recess 7 opened to the piston head 8 at approximately 60 degrees
The recess 7 is formed such that the starting end 10 which is the key to the fan is deepest and the depth becomes shallower toward the tip 12 (see FIG. 1).

The recess 7 is arranged near the center of the piston head 8, and the starting end portion 10 thereof faces the opening end of the injection port 2 on the main combustion chamber side.

Of the left and right side surfaces 53, 53 of the recess 7, the side wall portion 50 near the starting end between the starting end 10 and the midway portion 54 near the tip end is cut and raised at a right angle as shown in FIG. As shown in FIG. 6, the intermediate side portion 52 up to the tip portion 12 is
The opening angle θ is expanded to form a smooth surface.

In this case, as the aspect of the wall angle of the left and right side surfaces 53, 53, for example, the side wall portion 50 near the starting end is formed in a so-called dovetail groove shape as shown in FIG. The height may be increased, or the intermediate side portion 52 may be formed into a curved surface that widens upward as shown in FIG. 8 so that air can be easily drawn into the recess 7 from the outside.

Further, the shape of the recess 7 in the longitudinal direction is such that the starting end 10 is formed in a spherical shape, and the portion from the starting end 10 to the leading end 12 is a flat surface having an upward slope so that the spherical surface and the flat surface can communicate smoothly. It is a thing.

On the other hand, FIG. 4 shows a second embodiment of the present invention, in which the left and right side surfaces 53, 53 of the recess 7 are divided into three parts, that is, a starting end portion 50, an intermediate side portion 52 and a tip end portion 55. Both the portion 50 and the tip portion 55 are cut and raised at right angles (see FIGS. 5 and 9; however, FIG. 9 is a sectional view taken along the line RR of FIG. 4), and only the intermediate side portion 52 is provided. As shown in FIG. 6, the open angle .theta.

In this case, as shown in FIG. 8, the intermediate side portion 52 is formed into an upwardly spread curved surface so that both the portions 50 and 55 near the start end and near the tip end.
The dovetail groove may be formed as shown in FIG.

In addition, as a third embodiment of the present invention, the intermediate side portion 52 formed on the continuous upward spreading surface in the first and second embodiments.
It is also possible to provide a plurality of slanted open grooves in a direction orthogonal to the left and right side surfaces 53, so to speak, by providing intermittently.

Further, the recess 7 may have a shape that becomes shallower as it goes from the starting end portion 10 to the leading end portion 12, and therefore the shape in the longitudinal direction is not limited to the above-described embodiment, and the following cases are also acceptable.

That is, FIG. 14 shows a first modification of the recess 7 in the longitudinal direction,
The starting end 10 is cut down to a flat surface 30 that slopes backward, and a flat surface 31 having the same depth is formed from the starting end 10 to the middle part of the recess, and the part from the middle part to the tip 12 is recessed downward. As the single curved surface 32 (having a radius of curvature in the front-rear direction), the single curved surface 32 is smoothly continuous with the flat surface 31.

FIG. 15 shows a second modification of the recess 7 in the longitudinal direction, and in the first embodiment, the cut-down start portion of the starting end portion 10 is formed into a curved surface so that the recess 7 and the upper wall surface of the piston head 6 are separated from each other. Since they are connected by a smooth continuous surface, it is possible to prevent the formation of sharp corners at the starting end portion 10 and prevent cracks and heat points from occurring.

FIG. 16 shows a third modification of the recess 7 in the longitudinal direction, and in the first modification, a portion from the middle part of the recess to the tip portion 12 is formed on a flat surface 34 having a forward rising slope, The central and rear flat surfaces are connected in a polygonal line shape.

FIG. 17 shows a fourth modification of the recess 7 in the longitudinal direction, in which the start end portion 10 of the first modification is cut down into a vertical flat surface.

[Brief description of drawings]

1 to 9 show an embodiment of the present invention, and FIG.
2 is a plan view of a piston head showing an embodiment, FIG. 2 is a right side view of a vertical section around a piston head, FIG. 3 is a right side view of a vertical portion of a vertical diesel engine, and FIG. Figures equivalent, Figure 5 is P in Figure 1 or 4
Fig. 6 is a sectional view taken along the line P, Fig. 6 is Q- in Fig. 1 or Fig. 4.
A sectional view taken along the line Q, FIG. 7 is a view corresponding to FIG. 5 showing another embodiment of the side surface portion near the starting end portion, and FIG. 8 is a view corresponding to FIG. 6 showing another embodiment of the intermediate side portion, and FIG. 4 is a sectional view taken along line RR in FIG. 4, FIG. 10 is a view equivalent to FIG. 1 showing the prior invention, FIG. 11 is a schematic view of the nozzle, and FIGS. 12 and 13 are other modified examples of the nozzle. 1 and FIG. 14 to FIG. 17 are right side views of the longitudinal section of the main part of the piston head showing a modification of the recess in the longitudinal direction. 1 ... Main combustion chamber, 2 ... Injection port, 3 ... Vortex chamber, 4 ... Shaft center, 6 ... Piston, 7 ... Recess, 8 ... Piston head, 10 ... 7 start end, 12 ... … 7 tip, 53 …… both left and right sides.

Claims (1)

[Claims] 1. A vortex chamber (3) communicates with an eccentric portion of a main combustion chamber (1) of a diesel engine (E) through a nozzle (2), and an axial center (4) of the nozzle (2) is a vortex chamber. As it gets closer to the main combustion chamber (1) from (3), it is oriented so as to be closer to the center of the main combustion chamber (1), and the combustion airflow is blown from the injection port (2) to the piston head (8) near the top dead center. In the vortex chamber type combustion chamber of the diesel engine configured as described above, when the piston (6) is near the top dead center, a recess for guiding the combustion airflow ejected from the nozzle (2) in the main combustion chamber (1) ( 7) to the piston head (8) and the starting end (1
The vortex chamber type of a diesel engine is characterized in that it is formed in a shape that spreads left and right as it goes from 0) to the tip (12), and both left and right side surfaces (53, 53) of the recess (7) are spread upward. Combustion chamber.