JPH084582A - Scavenging chamber structure of two-cycle engine - Google Patents

Abstract

PURPOSE:To improve rigidity of the whole of a cylinder block and to sufficiently ensure the passage area of a blow-by gas passage. CONSTITUTION:Formation of the scavenging structure of a two-cycle engine is such that a plurality of cylinders 3 are disposed in series at the upper part of a cylinder block 1 and a scavenging chamber 5 with which the peripheries of a plurality of the cylinders 3 are surrounded and which consists of single chambers communicated with each other is formed, and a scavenging introduction opening part 6 is formed on one side of the scavenging chamber 5. Vertically extending-through blow-by gas passages 12 are formed in the positions, situated facing each other between the cylinders 3 and 3, of the scavenging introduction opening part 6. The passage wall thereof is worked as a cylindrical reinforcing stay and eliminates deficiency in rigidity owing to the scavenging introduction opening part 6 and improves rigidity of the whole of the cylinder block 1, and sufficiently ensure the total passage area of the blow-by gas passage 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scavenging chamber structure for a two-cycle engine, and more particularly to a scavenging chamber structure for a uniflow type scavenging method (single flow scavenging) multi-cylinder two-cycle engine.

[0002]

2. Description of the Related Art In general, a uniflow type scavenging system is adopted in a two-cycle diesel engine. As a scavenging chamber structure of this kind of uniflow type two-cycle engine, as shown in FIGS. 6 to 8, water cooling is performed so as to surround each cylinder 22 above a cylinder block 21 in which a plurality of cylinders 22 are arranged in series. A jacket 23 is formed, a scavenging chamber 24 is formed in the lower part of the scavenging chamber 24, which surrounds each cylinder 22 and communicates with each other, and a scavenging introduction opening 25 is formed on one side of the scavenging chamber 24. It has been known. 26
Is a cylinder liner fitted to the inner circumference of the cylinder 22, and a plurality of scavenging ports 27 opening to the scavenging chamber 24 are formed at appropriate intervals in the circumferential direction. 28 is the cylinder liner 2
It is a piston fitted in 6 so as to be vertically slidable.

In such a scavenging chamber structure, by supplying scavenging air from a scavenging pump (not shown) to the scavenging chamber 24 through the scavenging introduction opening 25, the piston 28 descends and the scavenging port 27 opens. Then, the scavenging air flows into the cylinder 22 to perform the scavenging, and the air is exhausted from the exhaust port provided in the cylinder head.

[0004]

However, when the scavenging chamber 24 and the scavenging introduction opening 25 having the above-described structure are formed in the cylinder block 21, the upper portion and the lower portion of the cylinder block 21 are separated by the scavenging chamber 24 portion, There is a problem that the overall rigidity of the cylinder block 21 is reduced.

Further, since the scavenging gas introduction opening 25 is provided on one side of the scavenging chamber 24, a blow-by gas passage can be formed on one side of the cylinder block 21 where the scavenging gas introduction opening 25 is formed. However, there was a problem that it was difficult to secure a sufficient passage area.

In view of such conventional problems, the present invention has
An object of the present invention is to provide a scavenging chamber structure for a two-cycle engine in which the overall rigidity of the cylinder block can be increased and the passage area of the blow-by gas passage can be sufficiently secured.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a plurality of cylinders are arranged in series on an upper portion of a cylinder block to form a scavenging chamber consisting of a single chamber that surrounds the plurality of cylinders and communicates with each other. However, a scavenging gas introduction opening is formed on one side of the scavenging chamber, and a blow-by gas passage that vertically penetrates is formed at a position facing each other between the cylinders of the scavenging gas introduction opening.

Preferably, ribs project from the bottom wall between the cylinders of the scavenging chamber, the blow-by gas passage wall on one side, and the side wall on the other side.

[0009]

According to the present invention, since the blow-by gas passages that penetrate vertically are formed at positions facing each other between the cylinders of the scavenging introduction opening, the blow-by gas passage walls act as a cylindrical reinforcing column. The lack of rigidity due to the provision of the scavenging chamber and the scavenging introduction opening can be eliminated to increase the overall rigidity of the cylinder block, and a blow-by gas passage is also formed on one side of the cylinder block, so the total passage area of the blow-by gas passage Can be sufficiently secured.

Further, by providing a rib over the bottom wall between the cylinders of the scavenging chamber, the blow-by gas passage wall on one side, and the side wall on the other side, the scavenging chamber can be further reinforced between the cylinders, and the rigidity is further increased. Can be increased.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

1 to 3, reference numeral 1 is a cylinder block of a uniflow type scavenging multi-cylinder two-cycle engine, and a plurality of (three in the figure) cylinders 3 are connected in series in a cylinder arranging portion 2 above the cylinder block. It is installed in.
A water cooling jacket 4 is formed at an upper portion of the cylinder arranging portion 2 so as to surround each of the cylinders 3, and a scavenging chamber 5 that surrounds the periphery of each of the cylinders 3 and is composed of a single chamber communicating with each other is formed at a lower portion thereof. ing. Further, a scavenging gas introduction opening 6 communicating with the scavenging chamber 5 is formed on one side surface of the upper portion of the cylinder block 1 so as to project outward on one side. This scavenging introduction opening 6 is formed long in the arrangement direction of the cylinders 3 except both ends of the cylinder block 1, and the height dimension in the vertical direction is also larger than that of the scavenging chamber 6, and functions as a surge tank. Is made to do.

A cylinder liner 7 is fitted to the inner circumference of each cylinder 3 as shown by an imaginary line, and a scavenging port 8 opening to the scavenging chamber 5 at a position corresponding to the upper part of the scavenging chamber 5 of the cylinder liner 7. Are formed at appropriate intervals in the circumferential direction. A piston 9 is fitted in the cylinder liner 7 so as to be vertically slidable.

A skirt portion 11 forming a crank chamber 10 is formed in the lower portion of the cylinder block 1. A blow-by gas passage 12 penetrating from the crank chamber 10 toward the upper end surface of the cylinder block 1 is formed by vertically penetrating a position of the scavenging introduction opening 6 facing between the cylinders 3 and 3.

As shown by a phantom line in FIG. 2, a scavenging pump 13 is connected to the scavenging introduction opening 6 so as to supply a scavenging air flow. Although not shown, a cylinder head equipped with an exhaust valve and a fuel injection valve is joined to the upper surface of the cylinder block 1.

In the above construction, the piston 9 descends to open the scavenging port 8 while the scavenging air is being pumped from the scavenging pump 13 to the scavenging chamber 5 through the scavenging introduction opening 6.
By opening the exhaust valve provided in the cylinder head, the combustion exhaust gas is discharged from the exhaust port and the scavenging air flows into the cylinder 3 to perform scavenging. At that time, the scavenging chamber 5 and the scavenging introduction opening 6 function as a surge tank, and the intake pulsation due to the scavenging performed by shifting the timing between the cylinders 3 is absorbed, and smooth and uniform scavenging is performed stably. Be seen. Further, the blow-by gas flowing out into the crank chamber 10 is returned to the scavenging path through the blow-by gas passage 12 and the cylinder head.

According to the present embodiment, the blow-by gas passage 12 is formed vertically through the scavenging gas introduction opening 6 between the cylinders 3 and 3, so that the blow-by gas passage 12 has a cylindrical wall. To act as a reinforcing pillar in the shape of a cylinder, eliminate the lack of rigidity between the upper portion and the middle portion of the cylinder block 1 caused by forming the scavenging chamber 5 and the scavenging introduction opening 6, and increase the overall rigidity of the cylinder block 1. You can Further, since the plurality of blow-by gas passages 12 are formed on one side of the cylinder block 1, the total passage area of the blow-by gas passages is sufficiently secured.

Next, another embodiment of the present invention will be described with reference to FIGS. The same components as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the cylinder 3 of the scavenging chamber 5,
A bow-shaped rib 14 is provided so as to extend over the bottom wall between the three, the inner side wall of the blow-by gas passage 12 on one side, and the side wall on the other side. By projecting such ribs 14,
Furthermore, since the scavenging chamber 5 can be reinforced between the cylinders 3 and 3, the overall rigidity of the cylinder block 1 can be further enhanced. Further, since the rib 14 has a function of limiting the interference of the scavenging air flow between the cylinders, the scavenging efficiency can be improved by this.

[0020]

As described above, according to the scavenging chamber structure of the two-cycle engine of the present invention, the blow-by gas passages vertically penetrating are formed at the positions facing each other between the cylinders of the scavenging introduction opening. The blow-by gas passage wall acts as a cylindrical reinforcing strut, eliminating the lack of rigidity due to the provision of the scavenging chamber and the scavenging introduction opening, and increasing the overall rigidity of the cylinder block. Since the gas passage is formed, a sufficient passage area of the blow-by gas passage can be secured.

Further, by providing ribs protruding from the bottom wall between the cylinders of the scavenging chambers, the blow-by gas passage wall on one side and the side wall on the other side, the scavenging chambers can be further reinforced between the cylinders and the rigidity is further increased. Can be increased.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a cylinder block according to an embodiment of the present invention.

FIG. 2 is a cross-sectional plan view taken along the line AA of FIG.

FIG. 3 is a partial schematic front view of an upper portion of the cylinder block of the embodiment.

FIG. 4 is a vertical sectional side view of a cylinder block according to another embodiment of the present invention.

5 is a cross-sectional plan view taken along the line BB of FIG.

FIG. 6 is a vertical sectional side view of a cylinder block in a conventional example.

7 is a cross-sectional plan view taken along the line CC of FIG.

FIG. 8 is a partial schematic front view of an upper portion of a conventional cylinder block.

[Explanation of symbols]

 1 Cylinder Block 3 Cylinder 5 Scavenging Chamber 6 Scavenging Introduction Opening 12 Blow-by Gas Passage 14 Rib

Claims (2)

[Claims] 1. A plurality of cylinders are arranged in series on an upper part of a cylinder block to form a scavenging chamber composed of a single chamber which surrounds the circumference of each of the plurality of cylinders and communicates with each other. One side of the scavenging chamber. A scavenging chamber structure for a two-cycle engine, characterized in that a scavenging gas introduction opening is formed in the scavenging gas, and a blow-by gas passage that vertically penetrates is formed at a position facing each other between the cylinders of the scavenging gas introduction opening. 2. A scavenging chamber for a two-cycle engine according to claim 1, wherein ribs are provided so as to extend over the bottom wall between the cylinders of the scavenging chamber, the blow-by gas passage wall on one side, and the side wall on the other side. Construction.