JPH04265451A - Two cycle engine piston - Google Patents

Abstract

PURPOSE:To improve the cooling performance and reduce the weight by providing a cavity part inside at least upper outer circumferential part over the inside of the piston upper circumferential part and top face of a two cycle engine, and sealing sodium (Na) in almost the half of the capacity of this cavity part. CONSTITUTION:Inside the upper outer circumferential part 2 of the piston of a two cycle engine, a cavity part 3 is arranged. Sodium 4 is pored in the cavity part 3 by the amount corresponding to almost the half of the capacity of the part 3. This Na 4 is applied from a pouring port 5 arranged at one end of the cavity part 3 and then sealed with a cover 6. The sealed Na 4 is liquefied with heat received by the top face of the piston at the low melting point of 93 deg.C. Na 4 is then stirred inside the cavity 3 and heat received by the top face difused toward the skirt of the lower part to lower the temp. at the top face and cancel heat unbalance in the piston 1 itself. It is thus possible to prevent occurrence of trouble such as scuffing of the piston and the like and lighten weight so as to decrease inertia.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston for a two-stroke engine that is capable of improving heat dissipation.

0002

[Prior Art] The piston of a two-stroke engine is shown in Fig. 4.
As shown in the figure, the wall thickness near the top surface B of the piston A is increased to withstand the combustion pressure that the top surface B receives, and to increase the heat capacity. In addition, some pistons for four-cycle engines have a cavity inside the top surface to allow lubricating oil to enter therein, thereby promoting cooling with the lubricating oil. For example, see Utility Model Application Publication No. 1-142549.

[0003] The piston of a two-stroke engine is cooled by the fuel sucked into the cylinder, and there is a limit to cooling. As a result, insufficient cooling occurs, causing problems such as scuffing and ring sticking on the sliding surface of the outer circumference of the piston. Further, if the wall thickness near the top surface of the piston is increased, the weight of the piston increases, and there is a problem that the inertia during reciprocating movement of the piston increases.

[0004] In view of this, the present invention aims to provide a piston for a two-stroke engine that can improve cooling performance and reduce the weight of the piston by diffusing the heat received near the top surface of the piston toward the lower skirt. purpose.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the piston of the two-stroke engine of the present invention has a cavity inside the upper outer periphery of the piston and the top surface from the upper outer periphery, at least inside the upper outer periphery. The present invention is characterized in that approximately half of the volume of the cavity is filled with sodium.

[0006]

[Operation] Since the sodium sealed in the cavity has a melting point of 93°C, when the top surface of the piston receives heat from the combustion gas and rises in temperature, the sodium liquefies. Then, the liquefied sodium inside the cavity is stirred, and the heat received by the top surface is diffused toward the lower skirt, which prevents the top surface from overheating and maintains it at an appropriate temperature. In this way, the thermal imbalance of the piston itself can be resolved.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to FIGS. 1 to 3. 1 and 2 show one embodiment of the present invention. A cavity 3 is provided inside the upper outer periphery 2 of a piston 1 of a two-stroke engine. Then, sodium 4 in an amount approximately half the volume of the cavity 3 is injected into the cavity 3. Sodium 4 is injected from an injection port 5 provided at one end of the cavity 3, and is sealed with a stopper 6.

FIG. 3 shows another embodiment of the invention. In this case, in addition to the upper outer periphery of the piston 1 of the two-stroke engine, a cavity 3 is provided extending inside the top surface 7. Similarly, sodium 4 in an amount approximately half the volume of the cavity 3 is injected into the cavity 3, and the sodium 4 is sealed with a stopper 6.

The sodium 4 sealed in the cavity 3 is 9
It has a low melting point of 3° C. and is liquefied by the heat of the combustion gas that the top surface 7 of the piston 1 receives. Then, the inside of the cavity 3 is filled with sodium 4
is stirred, and the heat received by the top surface 7 is diffused toward the lower skirt, lowering the temperature of the top surface 7 and increasing the temperature of the piston 1.
It can eliminate the thermal imbalance of itself.

0010

[Effects of the Invention] As explained above, since the present invention is constructed as described above, the sodium sealed in the cavity provided in the upper part of the piston is liquefied due to the rise in the temperature of the piston, and the thermal damage of the piston itself is reduced. It prevents imbalance and lowers the temperature at the top. The burden of cooling the piston with fuel can be reduced, the heat capacity can be increased with the same piston weight, and the piston can be made lighter. These prevent troubles such as piston scuffing and improve durability.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view showing one embodiment of the present invention.

FIG. 2 is a longitudinal side view showing an embodiment of the present invention.

FIG. 3 is a longitudinal sectional side view showing another embodiment of the present invention.

FIG. 4 is a longitudinal sectional front view showing a piston of a conventional two-stroke engine.

[Explanation of symbols]

1 Piston 2 Upper outer circumference 3 Cavity part 4 Sodium 7...Top surface

Claims (1)

[Claims] Claim 1: A cavity is provided inside the upper outer periphery of the piston and the top surface from the upper outer periphery, at least inside the upper outer periphery, and approximately half of the volume of the cavity is filled with sodium. A two-stroke engine piston characterized by the following features: