JPS5928102Y2 - Cylinder cooling accelerator for air-cooled two-stroke engines - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a cylinder cooling promotion device for an air-cooled two-stroke engine.

As shown in FIG. 1, an air-cooled two-stroke engine has a cylinder A and a cylinder head B with a large number of cooling fins C,
D is installed vertically, and cooling fins C,
It is then sent to D and cooled down by the wind.

Cooling fins F are also provided around the exhaust hole E protruding from the cylinder A.

However, the exhaust hole E becomes particularly hot due to the exhaust heat, and the cooling fins F are insufficiently cooled, causing the cylinder A and the exhaust hole E to become hot.
Then, the temperature difference becomes large.

This tendency is particularly strong in cast iron cylinders due to their low heat conductivity.

As a result, accidents such as blow pie and seizing occur.

This idea has been improved in view of this point, and is described in the second section below.
An embodiment of the present invention shown in FIGS. 3 and 3 will be described.

A large number of cooling fins 3 and 4 are provided upright on the cylinder 1 and the cylinder head 2.

Cooling fins 6 are also erected around the exhaust hole 5 protruding from the cylinder 1, and the cooling fins 6 extend in the same plane 1 as the upper end surface of the cylinder 1.

A gasket 7 made of a heat transfer material such as a copper plate is placed on the upper end of the cylinder 1, and the cylinder heads 2 are stacked and fastened with bolts or the like.

As shown in FIGS. 2 and 4, the cylinder head 2 has an overhang 2a formed above the exhaust hole 5, which corresponds to the cooling fin 6. It overhangs like 4γa.

The cooling fins 6 provided in the exhaust hole 5 are brought into contact with the cylinder head 2 via the gasket I, which is a heat transfer body.

Note that when the fin 6 is brought into contact with the gasket 7a, the fourth
As shown by diagonal lines in the figure, only the thickness of the fin 6 contacts the gasket, resulting in poor thermal conductivity, so as shown in FIG. If 6 is a continuous flat surface, the thermal conductivity can be improved.

The cylinder 1 is cast from cast iron or a light alloy, and the cylinder head 2 is cast from a light alloy with good thermal conductivity.

Thus, the combustion heat within the cylinder 1 and cylinder head 2 is cooled by the cooling fins 3 and 4.

After the combustion gas pushes down the piston, it passes through the narrow exhaust hole 5 and is released into the exhaust pipe, but heat is concentrated near the exhaust hole 5.
In particular, the area around the exhaust hole 5 becomes hot.

However, since the cooling fins 6 are brought into contact with the light alloy cylinder head 2 via the heat transfer gasket I,
Heat near the exhaust hole 5 is transmitted to the cylinder head 2, which has good cooling properties, through the cooling fins 6, and cooling can be promoted.

Therefore, cooling near the exhaust hole 5 is promoted, and the occurrence of blow pie and seizure can be suppressed.

As explained above, this invention is applicable to an air-cooled two-stroke engine in which a cylinder head made of light metal is connected to one end of a cylinder made of cast iron or light alloy through a gasket made of a heat transfer material. The upright cooling fins are formed so as to reach the same surface as the end surface of the cylinder,
The end face of the cooling fin is brought into contact with the overhang provided on the cylinder head corresponding to the cooling fin part through the gasket, so that the heat concentrated near the exhaust hole is transferred through the cooling fin. Through the body gasket, the heat can be released to the cylinder head, which has good cooling properties, and the concentrated heat near the exhaust hole can be cooled down.

Therefore, the occurrence of blow-by and seizure accidents can be reduced.

Furthermore, although the cooling fins provided in the exhaust holes are long, they are held down by the cylinder head via the heat transfer gasket, so vibrations can also be suppressed.

[Brief explanation of the drawing]

Fig. 1 is a side view showing a conventional example, Figs. 2 and 3 show an embodiment of the present invention, Fig. 2 is a longitudinal sectional view, and Fig. 3 is a second
Figure 4 is a cross-sectional view taken along the line X-X of Figure 2, Figure 5 is another embodiment corresponding to Figure 2, and Figure 6 is a cross-sectional view taken along the line X-X of Figure 2. It is a ZZ arrow cross-sectional view. 1...Cylinder, 2...Cylinder head, 5...Exhaust hole, 6...Cooling fin, T...Heat transfer body gasket.

Claims (1)

[Scope of Claim for Utility Model Registration] In an air-cooled two-stroke engine in which a cylinder head made of a light alloy is connected to one end of a cylinder made of cast iron or a light alloy through a gasket made of a heat transfer material, The provided cooling fins are formed so as to reach the same surface as the end surface of the cylinder, and the end surface of the cooling fin is brought into contact with an overhang portion provided corresponding to the cooling fin portion of the cylinder head via the gasket. It is characterized by: Cylinder cooling acceleration device for air-cooled 2-stroke engines.