JPH0642401A - Multi-cylinder two cycle engine - Google Patents

Abstract

PURPOSE:To constitute a multi-cylinder two cycle engine light compact and inexpensive, and make simple the structure of a cylinder block. CONSTITUTION:A scavenging air chamber 7 separated from the outside by means of a closing plate 8, at a side of a cylinder block 1 is arranged and communicated with each scavenge path, the scavenge paths are made simple for a simple structure of the cylinder block 1 and exhaust ports 10 corresponding to exhaust paths 6 for every cylinder are formed at the closing plate 8 and a scavenging supply port 9 is formed at an adequate plate. With such a constitution, a cylinder pitch becomes shorter than that in the case where the exhaust ports 10 and the scavenging supply port 9 are arranged at every cylinder 2, and the width of engine becomes narrow avoiding interferences of an exhaust manihold 11 with a scavenging air supply tube 12 and furthermore weighta nd cost are decreased without using an exhaust manihold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-cylinder two-cycle engine in which two or more cylinders are arranged in series and an exhaust passage and a scavenging passage are arranged on one side of the cylinder row.

[0002]

2. Description of the Related Art With the recent development of electronic control technology for automobile engines, for example, as disclosed in Japanese Utility Model Application Laid-Open No. 3-35210, scavenging pump is used to forcibly supply scavenging air from outside and fuel is injected by a fuel injection method. Supply
It is possible to realize a two-cycle engine in which oil is stored in the lower part of the crank chamber, and a two-cycle engine that can be installed in an automobile has been developed.

Further, a multi-cylinder two-cycle engine in which two or more cylinders are arranged in series is disclosed in, for example, Japanese Patent Laid-Open No.
JP-A-3-230946 discloses that each cylinder has a plurality of scavenging holes communicating with a scavenging passage and a single exhaust hole communicating with an exhaust passage.

In such a multi-cylinder two-cycle engine to which the schnee scavenging structure is applied, normally,
As shown in FIG. 6, a scavenging supply port 23 communicating with the scavenging passage and an exhaust port 24 communicating with the exhaust passage are formed for each cylinder 22 on one side surface of the cylinder block 21, and the scavenging manifold is provided at each scavenging supply port 23. An exhaust manifold 26 is connected to each exhaust port 24.

[0005]

However, in the structure shown in FIG. 6, the scavenging manifold 25 and the exhaust manifold 26 are provided at the scavenging supply port 23 and the exhaust port 24 provided for each cylinder 22 on one side surface of the cylinder block 21. In order to connect the scavenging air supply port 23 and the exhaust gas outlet port 24, it is necessary to secure a certain space or more, and the length of the engine in the cylinder arrangement direction (L direction) becomes long. A large space is required also in the width direction (W direction) of the engine in order to shift the arrangement position in the width direction of the engine so that the collecting pipes of the exhaust manifold 26 do not interfere with each other, and it is not easy to make it lightweight and compact. Moreover, since the shape of the scavenging passage that connects the scavenging hole and the scavenging supply port 23 is also complicated, the structure of the cylinder block 21 is also complicated. There are problems such increased cost with two manifolds 25 and 26 cause an increase in the weight because it is necessary.

In view of such conventional problems, the present invention has
It is an object of the present invention to provide a multi-cylinder two-cycle engine which can be constructed in a lightweight, compact and inexpensive manner and has a simple cylinder block structure.

[0007]

According to the present invention, two or more cylinders are arranged in series in a cylinder block, and an exhaust passage for each cylinder and a scavenging passage on both sides thereof are arranged on one side of the cylinder row. In the multi-cylinder two-cycle engine described above, each exhaust passage is opened at one side surface of the cylinder block, and a scavenging air chamber communicating with each scavenging passage is formed at one side of the cylinder block. It is characterized in that it is partitioned from the outside by a closing plate having an exhaust port formed at the opening part of the above, and a scavenging air supply port is formed at an appropriate position of the closing plate.

[0008]

According to the present invention, a scavenging air chamber partitioned by a closing plate from the outside is provided on one side of the cylinder block, and the scavenging air chamber is communicated with each scavenging passage. Simplifies the structure of the cylinder block, and the closing plate has an exhaust port corresponding to each cylinder, and a scavenging supply port is formed in a proper place.Therefore, each cylinder has a scavenging port and an exhaust port. Since the cylinder pitch is increased to increase the length of the engine and the width of the engine is not increased to avoid interference between the scavenging manifold and the exhaust manifold, the scavenging manifold is not required. Therefore, the weight and cost can be reduced.

[0009]

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

In FIGS. 1 and 2, reference numeral 1 is a cylinder block in which three cylinders 2 are arranged in series. Each cylinder 2 is formed with a pair of scavenging holes 3a and 3b and one exhaust hole 4. The exhaust hole 4 is arranged on one side in the diameter direction orthogonal to the arrangement direction of the cylinders 2, and a pair of scavenging holes 3a and 3b are arranged on both sides of the exhaust hole 4. An exhaust gas outlet 5 is formed corresponding to each exhaust hole 4 on one side surface 1a in a direction orthogonal to the cylinder arrangement direction of the cylinder block 1, and each exhaust hole 4 and exhaust gas outlet 5 are respectively formed in an exhaust passage 6. It is connected. Further, as shown in FIG. 3, a single laterally long scavenging air chamber 7 is formed on one side of the cylinder block 1 so as to surround the exhaust passages 6 on three sides except the upper portion and extend downward. The scavenging air chamber 7 is sealed by a closing plate 8 mounted on one side surface 1a of the cylinder block 1 except for the exhaust gas outlet 5 portion.
In addition, the closing plate 8 is provided with a scavenging air supply port 9. The exhaust plate 1 corresponds to each exhaust gas outlet 5 in the closing plate 8.
0 is formed and the exhaust manifold 11 is connected. A scavenging air supply pipe 12 is connected to the scavenging air supply port 9.

As shown in FIGS. 3 to 5, between the adjacent cylinders 2 and 2, the scavenging passage 13 common to the scavenging holes 3b and 3a formed on the opposite sides of the cylinders 2 and 2 on both sides. Are formed in the upper part of the scavenging air chamber 7 by the side walls 6a of the exhaust passages 6 on both sides. This common scavenging passage 13 is branched at one end into both sides to form scavenging holes 3b, 3a.
And a scavenging guide rib 14 for guiding the flow direction of the scavenging air is provided at the branch portion. A boss 15 for screwing and fixing a cylinder head fixing bolt is provided on an upper portion of the scavenging guide rib 14. Further, the scavenging passage 16 for the scavenging holes 3a or 3b located outside the cylinders 2 at both ends is partitioned and formed in the upper portion of the scavenging air chamber 7 by the side wall 7a of the scavenging air chamber 7 and the side wall 6a of the exhaust passage 6. .

A water cooling jacket 17 is formed around the upper portion of each cylinder 1, and cooling water supply / discharge ports 18a, 18b and 19 are appropriately formed on both side surfaces and an upper surface of the cylinder block 1.

In the above structure, the cylinder block 1
A scavenging air chamber 7 which is partitioned from the outside by a closing plate 8 is formed on one side of the scavenging air chamber 7, and the scavenging air chamber 7 has a side wall 6a and a side wall 7a of the scavenging air chamber 7 on which scavenging air is scavenged. Since the passages 13 and 16 are partitioned and formed,
It is not necessary to newly form the scavenging passage in the cylinder block 1, and the structure of the cylinder block 1 is simplified.
Further, since the exhaust port 10 corresponding to each cylinder 2 is formed in the closing plate 8 and the exhaust manifold 11 is connected, and the scavenging supply pipe 12 is connected to the single scavenging supply port 9 formed in a proper position. Since the scavenging port and the exhaust port are provided for each cylinder 2, the cylinder pitch does not become large and the length of the engine does not become long, and the cylinder block 1 can be configured compactly in the cylinder 2 arrangement direction. Further, the exhaust manifold 11 and the scavenging supply pipe 12 do not interfere with each other, and the width of the engine does not increase in order to avoid the interference between the scavenging manifold and the exhaust manifold. Furthermore, since a scavenging manifold is not required, weight and cost can be reduced.

Even if the common scavenging air chamber 7 is provided, as long as the scavenging timing does not overlap between the cylinders 2, the scavenging state does not change or become unstable.

Further, a common scavenging passage 13 is provided in the scavenging holes 3a and 3b between the adjacent cylinders 2 and 2, and one end thereof is branched to both sides and connected to the scavenging holes 3a and 3b, so that they are independent from each other. The cylinder pitch P can be shortened as compared with the case where the scavenging passage is formed, and the engine can be made compact. Moreover, since the scavenging air is guided by the scavenging guide ribs 14 provided at the branch portion of the common scavenging passage 13, a suitable scavenging airflow can be obtained, and therefore, the scavenging efficiency can be improved and the engine performance can be enhanced. Further, since the scavenging guide rib 14 functions as a reinforcing rib of the boss 15 to which the cylinder head fixing bolt is coupled, even if the common scavenging passage 13 is formed between the cylinders 2 and 2, the strength required for fixing the cylinder head is high. Can be easily secured.

[0016]

According to the multi-cylinder two-cycle engine of the present invention, as described above, the scavenging air chamber partitioned from the outside by the closing plate is provided on one side of the cylinder block. Since it communicates with each scavenging passage, the scavenging passage can be simplified to simplify the structure of the cylinder block, and the closing plate has an exhaust port corresponding to each cylinder and a scavenging supply port in place. As a result, the cylinder pitch is increased because the scavenging port and exhaust port are provided for each cylinder, and the length of the engine is lengthened, and the width of the engine is increased to avoid interference between the scavenging manifold and the exhaust manifold. Since there is no such thing and the scavenging manifold is unnecessary, the weight and cost can be reduced, and therefore the engine is lightweight, compact and inexpensive. Can, and the structure of the cylinder block can be easily.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of main parts of a cylinder block and a scavenging / exhaust system in an embodiment of a multi-cylinder two-cycle engine of the present invention.

FIG. 2 is a cross-sectional plan view of an essential part of the embodiment.

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

FIG. 4 is a cross-sectional plan view of the cylinder block of the embodiment.

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

FIG. 6 is an exploded perspective view of a cylinder block and a main part of a scavenging / exhaust system of a conventional multi-cylinder two-cycle engine.

[Explanation of symbols]

 1 Cylinder Block 2 Cylinder 6 Exhaust Passage 7 Scavenging Air Chamber 8 Closing Plate 9 Scavenging Air Supply Port 10 Exhaust Port 13 Scavenging Passage 16 Scavenging Passage

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location F02M 35/10 301 R 9247-3G

Claims (1)

[Claims] 1. A multi-cylinder two-cycle engine in which two or more cylinders are arranged in series in a cylinder block and an exhaust passage for each cylinder and scavenging passages on both sides thereof are arranged on one side of the cylinder row. Each exhaust passage is opened on one side surface of the cylinder block, and a scavenging air chamber communicating with each scavenging passage is formed on one side of the cylinder block, and the scavenging air chamber is formed with an exhaust port at the opening portion of each exhaust passage. The multi-cylinder two-cycle engine is characterized in that it is partitioned from the outside by the closed plate, and a scavenging air supply port is formed at an appropriate position of the closed plate.