JP2565709Y2 - 2 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 two-cycle engine, and more particularly to a two-cycle engine having a scavenging system in which scavenging gas is forcibly supplied from outside by a scavenging pump.

[0002]

2. Description of the Related Art With the recent development of electronic control technology for automobile engines, scavenging pumps are used to externally purge air from the outside as disclosed in, for example, Japanese Utility Model Laid-Open Publication No. 3-35210 and Japanese Utility Model Laid-Open Publication No. 62-133945. A two-stroke engine, in which fuel is supplied by forcible supply and fuel injection, and oil is stored in the lower part of the crankcase, can be realized. Have been.

In such a two-cycle engine,
If the scavenging hole is opened in the peripheral surface of the cylinder chamber, lubricating oil will enter the scavenging hole during the ascent and descent strokes of the piston, and this oil will be supplied to the combustion chamber together with scavenging air during scavenging, Since the oil is burned and consumed, there is a disadvantage that the oil consumption increases.

To solve this problem, a means for preventing oil from entering the scavenging hole has been provided, and as shown in FIG.
A concave portion is formed in the vicinity of a scavenging hole 22 opened on the peripheral surface of the cylinder chamber 21 to form an oil reservoir 23, and oil entering from the scavenging hole 22 is stored in the oil reservoir 23. There is known one that is not supplied to the cylinder chamber 21. In such a configuration, it is manually instructed to periodically drain the oil in the oil reservoir 23.

[0005] In FIG. 3, reference numeral 24 denotes a piston, 25 denotes an exhaust hole formed on the upper surface of the cylinder chamber 21, and 26 denotes an exhaust valve for opening and closing the exhaust hole 25.

[0006]

Even if the oil reservoir 23 is provided in the vicinity of the scavenging hole 22 as described above, it is very troublesome to periodically drain the oil stored in the oil reservoir 23. Therefore, it often accumulates too much.
However, if too much oil accumulates, a large amount of oil enters the cylinder chamber 21 during scavenging and burns, not only increasing the oil consumption, but also causing the possibility of an overrun phenomenon due to the engine blowing up. There was a defect.

The present invention has been made in view of such conventional problems.
It is an object of the present invention to provide a two-stroke engine in which oil that has entered a scavenging hole is surely returned to a crankcase, which reduces oil consumption and eliminates engine blow-up due to oil combustion.

[0008]

In the two-stroke engine of the present invention, a scavenging pump is connected to a scavenging hole of a cylinder, and in a two-stroke engine in which oil is stored in a lower portion of a crankcase, oil that has entered the scavenging hole flows down. An oil reservoir for storing the oil is provided, an oil return passage communicating the oil reservoir with the crank chamber is provided, and an on-off valve that opens and closes when the engine is operating is provided in the oil return passage.

[0009]

According to the present invention, the oil that has entered the scavenging holes flows down and accumulates in the oil reservoir, so that the oil does not enter the combustion chamber with the scavenging air, and the oil consumption can be reduced. If too much oil is accumulated in the oil sump, a large amount of oil may enter the combustion chamber and cause the engine to blow up. However, in the present invention, when the engine stops, the open / close valve provided in the return passage opens and this return is made. The oil accumulated through the passage is automatically returned to the crankcase,
The engine does not blow up due to oil combustion.

[0010]

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

In FIG. 1, reference numeral 1 denotes a cylinder chamber, in which a scavenging hole 2 is provided on a peripheral side wall, and an exhaust hole 3 and an exhaust valve 4 for opening and closing the exhaust hole 3 are provided on an upper wall. Although not shown,
A spark plug and a fuel injector are also provided on the upper wall. A scavenging system 5 having an air filter, a scavenging pump, a throttle valve, and the like (not shown) is connected to the scavenging hole 2. A piston 6 is fitted in the cylinder chamber 1 so as to be movable up and down, and is connected via a connecting rod 7 to a crankshaft 9 disposed in the crank chamber 8. Oil for lubrication is stored in a lower portion of the crank chamber 8.

In the scavenging passage 10 communicating with the scavenging hole 2, a concave portion functioning as an oil reservoir 11 is provided at a lower portion near the scavenging hole 2. The bottom of the oil reservoir 11 communicates with the crank chamber 8 via a return passage 12, and an opening / closing valve 13 is interposed in the return passage 12. The opening / closing valve 13 is opened and closed so that the control unit 14 closes when the ignition switch 15 of the engine is on and opens when the ignition switch 15 is off.

In the above configuration, during operation of the engine, the oil stored in the lower part of the crank chamber 8 is repelled by the rotation of the crankshaft 9, scatters as oil mist, and adheres to the inner peripheral surface of the cylinder chamber 1. Then, the piston 6 is lubricated. As the piston 6 moves up and down, part of the oil adhering to the inner peripheral surface of the cylinder chamber 1 is gradually removed from the scavenging holes 2.
Invade. As it is, the oil that has entered the scavenging hole 2 is supplied into the cylinder chamber 1 together with the scavenging air, and is burned and consumed. Since the air accumulates in the cylinder 11, the air does not enter the cylinder chamber 1 with the scavenging air. Further, since the on-off valve 13 is closed, the scavenging passage 10 and the crank chamber 8 are shut off, and scavenging air does not leak into the crank chamber 8.

When the engine stops, the on-off valve 13 is opened, so that the oil accumulated in the oil reservoir 11 is automatically returned to the crank chamber 8 through the return passage 12. Thus, there is no possibility that a large amount of oil enters the cylinder chamber and burns during scavenging due to too much oil being stored in the oil sump 11. Thus, not only can the oil consumption be reduced without any maintenance, but also the occurrence of the overrun phenomenon due to the rising of the engine can be completely eliminated.

In the above embodiment, the oil reservoir 11 is formed so as to face the scavenging passage 10. However, as shown in FIG. Guide passage 1 to be discharged from scavenging passage 10
6 and an oil sump 17 at the end of the guide passage 16.
The oil reservoir 17 and the crank chamber 8 may communicate with each other through the return passage 12, and an opening / closing valve 13 may be interposed midway. According to such a configuration, it is possible to more reliably prevent the oil from entering the cylinder chamber 1 together with the scavenging air.

[0016]

According to the two-stroke engine of the present invention,
Since the oil that has entered the scavenging holes flows down and accumulates in the oil sump, the oil does not enter the combustion chamber with the scavenging air, so that the oil consumption can be reduced, and the oil is provided in the return passage when the engine stops. The open / close valve is opened, and the oil accumulated through this return passage is automatically returned to the crankcase, so that it is possible to prevent a large amount of oil from entering the combustion chamber and causing the engine to blow up due to maintenance-free operation. The effect of is exhibited.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional front view of a two-stroke engine according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a two-stroke engine according to another embodiment of the present invention.

FIG. 3 is a partial cross-sectional front view of a main part of a conventional two-stroke engine.

[Explanation of symbols]

 Reference Signs List 1 cylinder chamber 2 scavenging hole 8 crank chamber 11 oil reservoir 12 return passage 13 on-off valve 17 oil reservoir

Claims (1)

(57) [Scope of request for utility model registration] In a two-stroke engine in which a scavenging pump is connected to a scavenging hole of a cylinder and oil is stored in a lower part of a crank chamber, an oil sump in which oil flowing into the scavenging hole flows down and accumulates is provided. A two-stroke engine comprising: an oil return passage communicating with a chamber; and an on-off valve that closes when the engine is running and opens when the engine is stopped.