JPH03202620A - Two-cycle engine - Google Patents

Abstract

PURPOSE:To enhance the sealing performance and increase the strength by forming a crank case and a cylinder block in a single piece configuration in which the scavenging port in cylinder liner is located identical to the open end furnished on one side, and fixing a case cover bounding the suction passage to this open end. CONSTITUTION:A cylinder head 3 is fixed to the oversurface of a cylinder block 2 of the body 1 of engine concerned. This cylinder block 2 is formed in a single piece with a crank case 5, and the crack chamber 5a shall serve also as a pre-pressurizing chamber. One side of the cylinder block 2 and crack case 5 is formed at the open end, and a case cover 8 is fixed to the junction faces 7 of them, and a partition plate 9 to make setting of the pre-pressurizing capacity is provided at the case cover 8 on its crank chamber 5a side. A cylinder liner 6 is formed by inclusion casting in the direction in which one of the scavenging ports 18 is located identical to the abovementioned open end, and the side wall around the scavenging port 18 is left open to the junction face 7 side, and this end face is subjected to post-processing into a plane flush with the junction face 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a two-stroke engine in which a cylinder block, a crankcase, etc. are integrally formed.

[Prior art and problems to be solved by the invention] Generally,
A two-stroke engine with a crankcase compression system has a scavenging port that communicates the crank chamber and the combustion chamber. The engine is constructed as a separate component.

In other words, in two-stroke engines, the scavenging passage between the combustion chamber and the crank chamber is roughly divided into those in which the scavenging passage is formed by the cylinder liner and those in which the scavenging passage is formed by the cylinder block itself. When casting, the crank chamber is naturally larger than the cylinder diameter in any case, so there is an undercut in the mold release direction on the cylinder side, and it is necessary to mold the crankcase and cylinder block separately. .

In this case, as shown in FIG. 3, the crankcase 20 is often composed of halves 20a and 20b, and the crankcase 20 and the cylinder block 22 are joined together via a gasket or the like, and then connected at 21. Fastened with bolts and nuts.

However, since the explosion pressure of the engine is repeatedly applied to the mating surface 21, bolts and nuts are likely to loosen, which may cause oil or gas leakage from the mating surface 21.

Furthermore, in order to apply a sufficient fastening force to the mating surface 21 against the explosion pressure of the engine, it is necessary to increase the strength of the flange of the fastened portion, which inevitably increases the wall thickness and increases the weight.

[Object of the Invention] The present invention was made in view of the above circumstances, and it is possible to integrally form a crankcase and a cylinder block to prevent oil leakage and gas leakage, ensure strength, and reduce the weight of the engine. The purpose is to provide a two-stroke engine that can achieve the following.

[Means and effects for solving the problem] In order to achieve the above object, the two-stroke engine according to the present invention has a crankcase and a cylinder block, and the scavenging port of the cylinder liner is aligned with the open end provided on one side. The case cover is integrally formed and a case cover forming a scavenging passage is attached to the open end.

That is, the crankcase and the cylinder block are integrally formed, with an open end provided on one side and a scavenging port of the cylinder liner aligned with the open end. Then, a case cover is attached to the open end to form a scavenging passage.

[Embodiments of the invention] Hereinafter, the present invention will be described in detail with reference to the drawings.

1 and 2 show one embodiment of the present invention, with FIG. 1 being a cross-sectional view of a two-stroke engine according to the present invention, and FIG. 2 being a perspective view of a cylinder liner.

In FIG. 1, reference numeral 1 denotes an engine body, 2 a cylinder block, and 3 a cylinder head mounted on the upper surface of the cylinder block 2. A spark plug 4 is mounted on the cylinder head 3.

Furthermore, the cylinder block 2 is formed integrally with the crankcase 5, and the crankcase 5 has a crank chamber 5a.
doubles as the preload chamber. Furthermore, the cylinder block 2
A cylinder liner 6 is cast into the cylinder liner 6.

Further, one side of the cylinder block 2 and the crankcase 5 is an open end, a case cover 8 is attached to the mating surface 7 of the open end, and a preload volume is set on the crankshaft of the case cover 8. A partition plate 9 is attached.

Further, a piston 10 is slidably inserted into the cylinder liner 6, and the piston 10 and the crankshaft 11
The crankshaft 11 is supported by a main bearing 13 which is connected to the crankcase 5 through a connecting rod 12 and is provided in the crankcase 5.

Note that reference numeral 13a is an oil seal that seals the open end of the crankcase 5 on the main bearing 13 side, and also the top surface of the piston 10.

A combustion chamber 14 is formed surrounded by the inner wall of the cylinder liner 6 and the inner surface of the cylinder head 3.

As shown in FIG. 2, the cylinder liner 6 is provided with an intake port 15 and an exhaust port 16, and is connected to the crank chamber 5a at a symmetrical position with both ports 15 and 16 in between. A pair of communicating scavenging ports 17,18 are drilled therein.

Further, a passage wall 17a is provided on the outer periphery of the cylinder liner 6 to communicate one scavenging port 17 with the crank chamber 5a to form a scavenging passage 17b, and a side wall 18a surrounding the other scavenging port 18 stands upright. It extends toward the crank chamber 5a.

The cylinder liner 6 is connected to the other scavenging port 1.
8 is cast in a direction that corresponds to the open ends of the cylinder block 2 and the crankcase 5, and the side wall 18a around the scavenging port 18 is opened toward the mating surface 7, and its end surface is aligned with the mating surface 7. Post-processed to the same plane.

Further, the scavenging port 18 is provided in the cylinder liner 6.
Service hole 1 on the side for the piston pin (not shown)
9 is drilled.

The engine main body 1 with the above configuration is manufactured by first molding the cylinder liner 6 from cast iron or the like, then forming the cylinder block 2,
The crankcase 5 is made of a light alloy such as an aluminum alloy, and is integrally molded with the cylinder liner 6 cast therein by die-casting or the like.

At this time, since one side of the cylinder block 2 and the crankcase 5 is an open end, the mold for the crank chamber 5a can be released from the open end side.
The cylinder block 2 and the crankcase 5 can be integrally formed.

After the cylinder liner 6 is cast and integrally molded, the mating surface 7 of the open end is machined, and the oil seal 13a, main bearing 13, and crankshaft 11 are assembled.

Next, the piston 10 and the connecting rod 12 are attached to the crank chamber 5.
8, the connecting rod 12 is assembled to the crankshaft 11, and the mating surface 7 of the open end is assembled.
A piston pin (not shown) is inserted from the side into a service hole 19 formed in the cylinder liner 6 to connect the piston 10 and the connecting rod 12.

Then, a partition plate 9 is attached to the crank chamber 5a, a case cover 8 is attached to the mating surface 7, and the cylinder head 3 is attached to the cylinder block 2 via a gasket.

As a result, the piston 10. The strength of the combustion chamber 14 against the explosion pressure acting through the connecting rod 12 is greatly improved, and the overall weight can be reduced.

Although this embodiment has been described using a crankshaft cantilever engine, the present invention is not limited to this embodiment.

[Effects of the Invention] As explained above, according to the present invention, the crankcase and the cylinder block are integrally formed with the scavenging port of the cylinder liner aligned with the open end provided on one side, and the scavenging port of the cylinder liner is aligned with the open end provided on one side. By installing a case cover that forms a scavenging passage, oil and gas leaks from the mating surfaces of the crankcase and cylinder block, which were conventionally constructed as separate bodies, are eliminated, and the rigidity in the direction of combustion pressure is increased. It has excellent effects such as being able to reduce the weight of the engine while maintaining strength.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention, FIG. 1 is a sectional view of a two-stroke engine according to the present invention, FIG. 2 is a perspective view of a cylinder liner, and FIG. 3 is a conventional example. , is a sectional view of a two-stroke engine. 1... Engine body 2... Cylinder block 5... Crank case 6... Cylinder liner 8... Case cover 17.18... Scavenging port Fig. 3 14

Claims (1)

[Claims] 2. The crankcase and the cylinder block are integrally formed with the scavenging port of the cylinder liner aligned with the open end provided on one side, and a case cover forming a scavenging passage is attached to the open end. cycle engine.