JP2553932Y2 - Multi-cylinder two-cycle engine - Google Patents

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-stroke engine having a chenille scavenging structure 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. Things.

[0002]

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

Further, as a multi-cylinder two-stroke engine having two or more cylinders arranged in series, for example,
JP-A-3-230946 discloses an arrangement in which five scavenging holes and a single exhaust hole are arranged for each cylinder.
Also, in such a multi-cylinder two-stroke engine in which a schneele scavenging structure is applied, as shown in FIG.
In each cylinder 21 arranged in series, an exhaust hole 22 and an exhaust passage 23 communicating therewith are provided on one side of the cylinder row.
And a pair of scavenging holes 24a, 24b and scavenging passages 25a, 25b communicating therewith are arranged on both sides of the exhaust hole 22 to improve scavenging efficiency.

[0004]

However, in the configuration shown in FIG. 5, the exhaust passage 23 and the scavenging passages 25a, 25b on both sides of each cylinder 21 are arranged on one side of the cylinder row. There is a problem that the pitch between the cylinders 21 is increased, the overall length of the cylinder block is increased, and the engine cannot be configured compact.

Therefore, as shown in FIG. 6, a common scavenging passage 26 is provided between the adjacent cylinders 21, and the scavenging holes 24 of the adjacent cylinder 21 are branched at one end thereof.
b, 24a. However, it is difficult to secure an appropriate scavenging position and scavenging direction in such a configuration, and the scavenging flow shown by the arrow in FIG. 6 is obtained, and a suitable scavenging flow shown by the arrow in FIG. 5 is obtained. However, there is a problem that the scavenging efficiency is reduced due to the inability to perform the engine, and the engine performance is deteriorated.

The present invention has been made in view of such a conventional problem.
It is an object of the present invention to provide a multi-cylinder two-cycle engine capable of obtaining a good scavenging flow and improving scavenging efficiency while configuring the engine compactly.

[0007]

SUMMARY OF THE INVENTION The present invention is a multi-cylinder in which two or more cylinders are arranged in series and an exhaust passage for each cylinder and a scavenging passage on both sides are arranged on one side of the cylinder row. In a two-stroke engine, a common scavenging passage is formed between adjacent cylinders, and one end of the common scavenging passage is branched to both sides and connected to scavenging holes formed on opposing sides of both cylinders. A scavenging guide rib is provided at a branch portion of the scavenging passage, and a boss having a screw hole for screwing a cylinder head fixing bolt is provided above the scavenging guide rib.

[0008]

According to the present invention, the scavenging passage is shared between adjacent cylinders, and one end of the scavenging passage is branched to both sides and connected to the scavenging holes of both cylinders, so that the cylinder pitch can be shortened and the engine can be made compact. And a scavenging guide rib is provided at a branch portion of the scavenging passage, so that scavenging air can be guided to obtain a suitable scavenging flow, scavenging efficiency can be improved, and engine performance can be improved. The guide ribs function as reinforcing ribs for the bosses to which the cylinder head fixing bolts are connected, so that even if a common scavenging passage is formed between the cylinders, the strength necessary for fixing the cylinder head can be easily secured.

[0009]

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

1 to 4, reference numeral 2 denotes a cylinder block in which three cylinders 1 are arranged in series. Each cylinder 1 has a pair of scavenging holes 3a, 3b and one exhaust hole 4. The exhaust hole 4 is arranged on one side in a diameter direction orthogonal to the arrangement direction of the cylinders 1, and a pair of scavenging holes 3 a and 3 b are arranged on both sides of the exhaust hole 4. Exhaust gas outlets 5 are formed on one side surface 2a in a direction orthogonal to the cylinder arrangement direction of the cylinder block 2 so as to correspond to the exhaust holes 4, and the exhaust holes 4 and the exhaust gas outlets 5 are respectively formed in the exhaust passage 6. It is connected. As shown in FIG. 2, a single horizontally long scavenging air chamber 7 is formed at one side of the cylinder block 2 so as to surround three sides except the upper part of each exhaust passage 6 and extend downward. A sealing plate (not shown) mounted on one side surface 2a is sealed except for the exhaust gas outlet 5, and the closing plate is provided with a scavenging air supply port.

A scavenging passage 8 common to the scavenging holes 3b and 3a formed on the opposing sides of the cylinders 1 and 1 on both sides is provided above the scavenging air chamber 7 between the adjacent cylinders 1 and 1. It is defined by the side walls 6a of the exhaust passages 6 on both sides. One end of the common scavenging passage 8 is branched to both sides and connected to the scavenging holes 3b and 3a, and a scavenging guide rib 9 for guiding the flow direction of the scavenging air is provided at the branch portion. A boss 11 having a screw hole 10 for screwing a cylinder head fixing bolt is provided above the scavenging guide rib 9.

A scavenging passage 12 for scavenging holes 3a or 3b located outside the cylinder 1 at both ends is formed above the scavenging air chamber 7 by a side wall 7a of the scavenging air chamber 7 and a side wall 6a of the exhaust passage 6. Have been.

A water cooling jacket 13 is formed around the upper part of each cylinder 1, and cooling water supply / discharge ports 14 a, 14 b, 15 are appropriately formed on both side surfaces and the upper surface of the cylinder block 2.

In the above configuration, the scavenging passage 8 common to the scavenging holes 3a, 3b between the adjacent cylinders 1, 1
Is provided, and one end thereof is branched to both sides and connected to the scavenging holes 3a and 3b. Therefore, the cylinder pitch P can be shortened as compared with the case where independent scavenging passages are formed, and the engine can be configured compact. Moreover, the common scavenging passage 8
The scavenging air is guided by the scavenging guide rib 9 provided at the branching portion, and a suitable scavenging flow as indicated by an arrow in FIG. 1 is obtained. Therefore, scavenging efficiency is improved and engine performance can be improved. Further, since the scavenging guide rib 9 functions as a reinforcing rib for the boss 11 to which the cylinder head fixing bolt is connected, even if a common scavenging passage 8 is formed between the cylinders 1 and 1, the strength required for fixing the cylinder head is obtained. Can be easily secured.

Even if the scavenging passage 8 is common to the adjacent cylinders 1, as long as the scavenging timing does not overlap between the adjacent cylinders 1 and 1, the scavenging state may fluctuate or become unstable. It does not become. Also, by keeping the scavenging timings of all the cylinders 1 from overlapping, even if scavenging air is supplied from a single scavenging air chamber 7 as in the above embodiment, the scavenging state of all the cylinders 1 may fluctuate. It does not become unstable.

[0016]

According to the multi-cylinder two-stroke engine of the present invention, the scavenging passage is shared between adjacent cylinders as described above, and one end is branched to both sides and connected to the scavenging holes of the cylinders on both sides. As a result, the cylinder pitch can be shortened, the engine can be made compact, and since the scavenging guide rib is provided at the branch portion of the scavenging passage, scavenging air can be guided to obtain a suitable scavenging flow, thereby improving scavenging efficiency. The scavenging guide ribs function as reinforcement ribs for the bosses to which the cylinder head fixing bolts are connected, so that even if a common scavenging passage is formed between the cylinders, the scavenging guide ribs are necessary for fixing the cylinder head. Strength can be easily secured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional plan view of a cylinder block in an embodiment of a multi-cylinder two-cycle engine of the present invention.

FIG. 2 is a front view of the upper part of the cylinder block of the embodiment.

FIG. 3 is a vertical side view taken along the line AA of FIG. 1;

FIG. 4 is a top view of the cylinder block of the embodiment.

FIG. 5 is a cross-sectional plan view of a cylinder block in a conventional multi-cylinder two-cycle engine.

FIG. 6 is a cross-sectional plan view of a cylinder block in a conventional multi-cylinder two-cycle engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder chamber 3a Scavenging hole 3b Scavenging hole 4 Exhaust hole 6 Exhaust passage 8 Common scavenging passage 9 Scavenging guide rib 11 Boss

Claims (1)

(57) [Scope of request for utility model registration] 1. A multi-cylinder two-stroke engine in which two or more cylinders are arranged in series and an exhaust passage for each cylinder and a scavenging passage on both sides thereof are arranged on one side of the cylinder row. A common scavenging passage is formed between the scavenging passages, and one end of the common scavenging passage is branched to both sides to be connected to scavenging holes formed on opposing sides of the cylinders on both sides, and scavenging guide is provided to a branch portion of the scavenging passage. A multi-cylinder two-stroke engine, comprising a rib, and a boss having a screw hole for screwing a cylinder head fixing bolt on the scavenging guide rib.