JPS5933843Y2 - 2 cylinder 2 cycle engine - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a crank chamber compression type two-cylinder two-stroke engine using a mixed lubrication system and equipped with a novel lubricating oil supply device.

In a 2-stroke engine, there are two methods for supplying lubricating oil to rotating and sliding parts: a mixed lubrication method in which fine particles of lubricating oil are mixed into the air-fuel mixture, and an oil tank and oil pump are installed to supply the necessary amount of lubrication. It is well known that there is a separate lubrication system in which oil is supplied separately from fuel.

The former method has the advantage that it does not require a complicated lubricant supply mechanism compared to the latter method, and is therefore widely adopted, especially in small engines.

However, on the other hand, lubrication using this mixed lubrication method has the disadvantage that the consumption rate of lubricating oil is high, and not enough lubricating oil is supplied to the desired lubricated parts, and unburned lubricating oil is mixed with exhaust gas. This has the disadvantage of being ejected outside the aircraft.

In this way, the release of unburned lubricating oil causes water pollution for outboard engines, and air pollution for motorcycle engines, so there is no way to solve this problem. The request had been made before.

This invention was developed in response to such requests.
A two-cylinder engine that utilizes the pressure difference between the two crank chambers between the two cylinders to supply lubricating oil intensively from the lubricating oil reservoir of the other cylinder to the large end of the connecting rod, achieving proper lubrication with a small amount of lubricating oil supplied. The present invention provides a two-cylinder compression type two-stroke engine.

Hereinafter, its configuration and the like will be explained in detail with reference to embodiments shown in the drawings.

FIG. 1 is a longitudinal cross-sectional view of the present invention applied to an outboard motor engine, and FIG. 2 is a cross-sectional view of a portion thereof.

In these figures, symbols 1a and lb are cylinders, 2a
, 2b are pistons that reciprocate within the cylinders 1 a and 1 b with a 180° phase difference, and 3 is a 18
0° crankshaft, 4 is a piston pin, 5 is a crank pin, 6 is a connecting gland that connects the crank pin 5 and piston 4, 7a and 7b are scavenging passages, and the opening end of this passage on the side of the exhaust chamber. is not closed even at bottom dead center.

8 is the crank chamber 9a, 9b of each cylinder 1a, 1b.
10a and 10b are carburetors,
Reference numeral 11 denotes a reed valve interposed in an intake passage 12 connecting the carburetor and the crank chambers 9a, 9b.

Reference numeral 13 denotes a lubricating oil supply port that opens into the scavenging passage 7a of the cylinder 2a located at the top, and 14 represents a lubricating oil supply port that opens below the crank chamber 9b of the cylinder 2b located at the bottom. It is connected to lubricating oil spout ports 15 and 16 that open into the crank chamber of the cylinder.

That is, this lubricating oil outlet 15,16 is located between 90' and 00' before the top dead center of the piston, as shown in FIGS. 2 and 3.
The lubricating oil spout 15.
16 are connected to the lubricating oil supply port 1 via check valves 17, respectively.
3.14 through an oil supply pipe 18.

In the embodiment shown in the figure, the lowest part of the scavenging passage 7a in the upper cylinder 1a and the crank chamber 9b in the lower cylinder 2b are used as the reservoir for lubricating oil (actually mixed in the fuel). However, the key point is that it is a part where a relative pressure difference occurs in relation to other cylinders, and any part may be used as long as it is a place where lubricating oil tends to accumulate.

In this regard, if this is applied to a motorcycle engine in which the engine is arranged approximately vertically, the lubricating oil reservoir will be located at the lowest part of the crank chamber, so the lubricating oil supply port will be provided in this area. .

In the figure, 21 indicates the outer shape of the cowling of the outboard motor, 22 is a drive shaft connected to a propeller shaft (not shown), 23 is a cylinder head, and 24 is a spark plug.

Figure 3 shows a two-cylinder crank chamber compression type 2 with a 180° crank.
This is a diagram showing the pressure difference in the crank chamber at 500 Orpm of a cycle engine, in which line a shows the pressure change in the crank chamber 9a, and line 2 shows the pressure change in the crank chamber 9b.

As is clear from this diagram, two glue and two ink chambers 9a
, 9b is greatest between 90° and 0° before top dead center.

This invention focuses on these points, and as mentioned earlier,
Position lubricating oil outlet 15°16 90° to 0° before top dead center
In other words, it was set at a location opposite to the large end 6'.

In the embodiment shown in the figure, this jet port is opened at a position directly facing the side of the bearing.

Therefore, the lubricating oil accumulated in the scavenging passage 7a and the crank chamber 9b is removed by the engine drive.
Due to the pressure difference within b, the fuel is supplied to the large end corresponding portion in the two ink chambers of the other cylinders, respectively.

That is, the lubricating oil accumulated in the scavenging passage 7a of the cylinder 1a passes from the supply port 13 through the oil supply pipe 18 and through the check valve 17 due to the pressurizing force in the crank chamber 9a and the negative pressure in the crank chamber 9b. The lubricant 2 is ejected from the lubricating oil ejection port 15 of the ink chamber 9b toward the large end 6'.

Similarly, the lubricating oil accumulated in the crank chamber 9b of the cylinder 1b is also directed toward the large end 6' from the lubricating oil spout 16 of the other crank chamber 9a through the supply port 14, the oil supply pipe 18, and the check valve 17. It is squirted.

As explained above, according to the present invention, lubricating oil is circulated and supplied by using the pressure difference between the two crank chambers caused by engine drive, so there is no need for a lubricating oil supply device with a complicated mechanical pump or the like. The structure is simple, and sufficient lubrication can be provided to the large end of the connecting rod, which requires the most lubricant supply.

In addition, since non-lubricating oil, such as lubricating oil that collects at the bottom of the scavenging passage or the bottom of the crank chamber, can be effectively used, the amount of lubricating oil can be reduced. There are also economical effects and effects in terms of preventing air and water pollution, such as a reduction in the amount of lubricating oil discharged with exhaust gas.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional side view of a two-cylinder two-stroke engine according to the present invention, and Fig. 2 is a cross-sectional view of the cylinder and crank chamber.
-b cross-sectional view, FIG. 3 is a diagram showing the pressure difference in the crank chamber in a crank compression two-cylinder two-stroke engine. 1a, Ib...Cylinder, 2a, 2b...
...Piston, 3...Crankshaft, 6...
... Connecting rod, 6'... Big end, 8
...Crankcase, 9a, 9b...
・Crank chamber, 13.14... Lubricating oil supply port,
15.16...Lubricating oil spout, 17...
・Check valve, 18... Oil supply pipe.

Claims (1)

[Scope of utility model registration request] A lubricating oil spout opening toward the large end of the connecting rod between 90° and 0° before top dead center of one cylinder communicates with a lubricating oil supply opening opening into a lubricating oil reservoir in the other cylinder. Crank chamber compression type 2 cylinder 2 featuring
cycle engine.