JPH06346737A - Scavenging device for diesel engine - Google Patents

Abstract

PURPOSE:To improve scavenging performance by allowing the uniform flow of the scavenging air into a cylinder through all scavenging ports. CONSTITUTION:All or a part of scavenging ports 13 is covered with a scavenging rectification member 30 having many drilled passage holes 31a for scavenging, and the position of the member 30, or the number, size, distribution or the like of the holes 31a is pertinently selected, thereby unifying the distribution of the scavenging air flowing into the ports 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scavenging device for a uniflow scavenging diesel engine.

[0002]

2. Description of the Related Art A conventional scavenging device for a uniflow scavenging two-stroke diesel engine is shown in FIG. In the figure, 11 is a cylinder, 12 is an exhaust valve for discharging the combustion gas in the cylinder 11, 13 is a large number of scavenging ports formed in the lower portion of the cylinder 11 at equal intervals along the circumferential direction, and 14 is A piston rod, 15 is a piston, 16 is a piston underside chamber, 17 is a scavenging trunk, 18 is a packing box, and 19 is a sealing packing.

The piston underside chamber 16 is a scavenging port
It is formed so as to surround 13 and communicates with the scavenging trunk 17 through a scavenging passage 20, and the lower surface of the piston 15 faces the piston underside chamber 16.

In the above diesel engine, the cylinder 11
The high-pressure combustion gas generated by the combustion of the fuel inside works outside by pushing down the piston 15 in the expansion stroke. This expansion process ends when the exhaust valve 12 opens and high-pressure combustion gas begins to be discharged from the exhaust valve 12. When the high-pressure combustion gas is discharged, the pressure in the cylinder 11 drops rapidly.

When the scavenging port 13 opens due to the lowering of the piston 15, the scavenging trunk 17 and the piston underside chamber 16
The high-pressure combustion air accumulated in the cylinder 11 flows into the cylinder 11 through the scavenging port 13 and pushes out the combustion gas remaining in the cylinder 11. This scavenging state continues until the piston 15 passes through the bottom dead center, moves to the rising stroke again, and closes the scavenging port 13.

After that, until the exhaust valve 12 is closed, a part of the combustion gas and the combustion air in the cylinder 11 flows out due to the pressure difference between the pressure in the cylinder 11 and the pressure on the downstream side of the exhaust valve 12. When the exhaust valve 12 is closed, the combustion air in the cylinder 11 is compressed for the next combustion due to the rise of the piston 15.

[0007]

In a uniflow scavenging two-cycle diesel engine, the combustion condition of fuel depends on how much air required for the next combustion can be supplied into the limited volume in the scavenging stroke. To be heavily involved.

However, in the above-mentioned conventional diesel engine, the air whose pressure is increased by the supercharger is the scavenging trunk.
17 and flows into the piston underside chamber 16 through the scavenging passage 20, but this air directly enters from the scavenging port 13 facing the scavenging passage 20, while the scavenging port 13 on the opposite side
Since the inflow of air does not occur smoothly, the pressure distribution of air in the piston underside chamber 16 becomes uneven. Therefore, there is a problem that the designed scavenging performance cannot be fully exhibited.

An object of the present invention is to solve the above problems and to allow scavenging air to uniformly flow into all cylinders from all the scavenging ports so that the designed scavenging performance can be sufficiently exhibited. is there.

[0010]

SUMMARY OF THE INVENTION The present invention has been invented in order to achieve the above-mentioned object, and the gist of the invention is that a large number of holes are formed in the lower portion of a cylinder along the circumferential direction thereof. In a uniflow scavenging type diesel engine equipped with a scavenging port of the above, and an exhaust valve for discharging combustion gas in the cylinder at the top, a scavenging rectifying member having a large number of scavenging passage holes is provided in all or part of the scavenging port. In the scavenging device of a diesel engine, the scavenging device is mounted around the cylinder so as to cover the cylinder.

The scavenging air rectifying member may be composed of a plate material having a large number of scavenging passage holes formed therein.

The scavenging air rectifying member may be composed of a wire net woven with a predetermined mesh.

A plurality of layers of the scavenging rectifying member can be provided.

[0014]

In the present invention, because of the above-described structure, the scavenging air flows into the scavenging port after passing through a large number of scavenging passages of the scavenging rectifying member. By appropriately setting the distance from the cylinder outer peripheral surface of the scavenging rectifying member, the number, size, and distribution of the scavenging passage holes, the distribution of the scavenging air around the cylinder is made uniform, and the scavenging is evenly distributed in each scavenging port. As a result, the scavenging performance in terms of design can be fully exerted.

[0015]

EXAMPLE A first example of the present invention is shown in FIG.
[FIG. 3] is an external perspective view of a main part, and (B) is a schematic sectional view of a scavenging device.

In the figure, 11 is a cylinder, 12 is an exhaust valve,
13 is a scavenging port, 15 is a piston, 14 is a piston rod,
18 is a packing box, 19 is a packing for sealing, 17 is a scavenging trunk, 16 is a piston underside chamber, 20 is a scavenging passage, and the above is the same as the conventional one shown in FIG.

Reference numeral 30 is a scavenging rectification member attached to the lower portion of the cylinder 11 so as to cover the scavenging port 13. The scavenging air rectifying member 30 is formed by molding a plate material 31 into a housing having an open inner circumference, and is attached to the lower part of the cylinder 11 over the entire circumference and covering all the scavenging ports 13. .

A large number of scavenging passage holes 31a are formed on the entire surface of the scavenging rectifying member 30 so that the scavenging air in the piston underside chamber 16 can be guided to the scavenging port 13 by passing through the scavenging passage hole 31a. Has become.

However, during operation of the diesel engine, the scavenging air pressure-fed by the supercharger flows into the scavenging trunk 17,
It is once stored here. The scavenging air stored in the scavenging trunk 17 flows into a piston underside chamber 16 provided for each cylinder 11 through a scavenging passage 20.

The scavenging air that has entered the piston underside chamber 16 is pressed by the lower surface of the piston 15 as it descends, passes through the scavenging passage hole 31a of the scavenging rectifying member 30 as shown by the arrow, and passes through the scavenging rectifying member. It flows into the cylinder 11 from the scavenging port 13 together with the opening of the scavenging port 13 through the annular space 32 in 30 and performs the desired scavenging action.

During the above scavenging action, the scavenging air inside the piston underside chamber 16 is installed at the scavenging rectifying member 30, the distance S between the scavenging rectifying member 30 and the outer surface of the cylinder 11, the size and number of the scavenging passage holes 31a and the circumferential direction. If the distribution along the longitudinal direction is appropriately selected, for example, by increasing the diameter of the scavenging passage hole 31a facing the opposite side of the scavenging passage 20, the scavenging air flowing into the scavenging port 13 in the circumferential direction of the cylinder 11 can be made. The distribution along can be made uniform. As a result, the scavenging amount flowing into each scavenging port 13 is made uniform, and the designed scavenging performance can be sufficiently exerted.

FIG. 2 shows a second embodiment of the present invention. In the second embodiment, the scavenging air rectifying member 40 is composed of a metal net 41 woven with an appropriate mesh. In the second embodiment, by changing the size of the mesh of the wire net 41 depending on the location, a uniform scavenging air flow can be created along the circumferential direction of the cylinder 11 like the scavenging air rectifying member 30 in the first embodiment. Obtainable.

FIG. 3 shows a third embodiment of the present invention. In the third embodiment, the scavenging rectification member 50 is formed by laminating an inner peripheral member 51 and an outer peripheral member 52, and each member 51,
A large number of scavenging passage holes 51a and 52a are formed in each 52. In the third embodiment, the size of the scavenging passage hole 51a of the inner peripheral member 51 and the size of the scavenging passage hole 52a of the outer peripheral member 52,
By appropriately changing the distribution, the number, etc., it is possible to adjust the scavenging performance in a wider range and more precisely than in the first embodiment.

The scavenging air rectifying member may be provided so as to cover only a part of the scavenging port 13.

[0025]

As described above, according to the present invention, since the scavenging rectifying member having a large number of scavenging passage holes formed therein is attached around the cylinder so as to cover the scavenging port, the scavenging air flow over the entire circumference of the cylinder. The pressure distribution can be made uniform and the scavenging air can be made to flow evenly from each scavenging port. As a result, the designed scavenging performance can be fully exerted.

[Brief description of drawings]

FIG. 1 shows a first embodiment of the present invention, (A) is an external perspective view of a main part, and (B) is a schematic sectional view of a scavenging device.

FIG. 2 is an external perspective view of a main part showing a second embodiment of the present invention.

FIG. 3 is an external perspective view of an essential part showing a third embodiment of the present invention.

FIG. 4 is a schematic sectional view of a conventional scavenging device.

[Explanation of symbols]

 11 Cylinder 12 Exhaust valve 13 Scavenging port 15 Piston 30 Scavenging rectifying member 31a Scavenging passage hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Motomura 1-1-1, Wadazakicho, Hyogo-ku, Kobe Sanryo Heavy Industries Ltd. Kobe Shipyard

Claims (4)

[Claims] 1. A uniflow scavenging diesel engine equipped with a plurality of scavenging ports formed in a lower portion of a cylinder along a circumferential direction thereof, and an exhaust valve for discharging combustion gas in the cylinder above the cylinder. 2. A scavenging device for a diesel engine, wherein a scavenging rectifying member having a large number of scavenging passage holes is attached around the cylinder so as to cover all or part of the scavenging port. 2. The scavenging rectification member is composed of a plate material having a large number of scavenging passage holes formed therein.
Scavenging device for the diesel engine described. 3. The scavenging device for a diesel engine according to claim 1, wherein the scavenging rectifying member is composed of a metal mesh woven with a predetermined mesh. 4. The scavenging device for a diesel engine according to claim 1, wherein a plurality of layers of the scavenging rectifying member are provided.