SU1255723A2 - Two-stroke carburettor liquid-cooled engine - Google Patents

Description

The invention relates to mechanical engineering, in particular to small-sized two-stroke engines for internal combustion of a motor vehicle, can be used to cool cylinders and their engine heads, and is an improvement of the known engine according to Aut. St. No. 1229391.

The purpose of the invention is to increase the engine durability of a more even distribution of floor temperature across the cylinder and its head, namely, increasing engine efficiency and durability of cylinder-head parts, reducing metal consumption, reducing exhaust gases, ensuring engine acceleration without using a radiator.

This goal is achieved by equalizing the temperature fields and lowering the temperature of the metal of the cylinder and cylinder head by increasing the coolant circulation rate and thereby creating the effect of automatically maintaining stable temperature of the parts when the engine speeds or loads change.

FIG. 1 shows a cylinder and a cylinder head, general view, in section; in fig. 2 shows section A-A in FIG. one.

The two-stroke carburetor engine contains a fluid cavity 1 formed by a cylinder of cylinder 2 and cylinder 3 of cylinder. The fill level of the cavity 1 with coolant is determined by the boundary tube 4, which is cast from the cylinder head 3. The liquid level is located above the outer wall 5 of the combustion chamber 6. Not filled with cooling 1, with its liquid the volume of cavity 1 forms a cavity 7 of the vapor-air phase, which at least two channels 8 and two channels 9, formed in the head 3 of the cylinder and channels 10 and 11, made in the cylinder 2, communicate with the lower front part 12 cavities 1. Channels 9 and 10 are located along the cooling air in front of the liquid cavity 1. The rear part 13 of cavity 1 is expanded compared to the front part 12 for a relative increase in the vapor-air phase. The fins of the cylinder 14 and the cylinder head 15 are preferably made on the outer surfaces of the channels 8-10 and the surfaces bounding the cavity 7 of the vapor-air phase. The best conditions for the removal of heat are created in the front part of the cylinder on the side of the discharge channel 16.

The proposed cooling system functions as follows.

At low engine loads, the heat from the hot surfaces of cylinder 2

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and the cylinder head 3 is transferred to the coolant, then to the outer ribbed surfaces of the cylinder 2 and the cylinder head 3, and is dispersed by the incoming flow of cooling air. The greatest amount of heat is taken away from the cooler in the zone of the pre-vapor phase of the liquid cavity 1, the outer surfaces of which have developed finning.

With increasing speed or load mode of the engine, the amount of heat that must be removed from the surfaces of the cylinder 2 and cylinder head 3, increases. In this case, heat exchange processes are intensified due to the development of coolant boiling on the surfaces of these parts, the pressure inside liquid cavity I rises. The most intense heat exchange takes place in the zone of the ribbed surfaces of cavity 7 and channels 8OH. The liquid cooled in these channels enters through the channels 11 into the main volume of the cavity 1, displacing the more heated liquid having a lower density into the zone of the cavity 7. As a result, the ordered circulation of the cooling liquid is organized. The fluid circulation rate depends mainly on the temperature difference (or density, respectively) of the coolant in the zones of the cavity 7 and channel 11, as well as on the hydraulic resistance of the channels 8-11. To create a sufficient temperature difference of the liquid, a preferential finning of the outer surfaces of these channels is provided.

When the engine operates on variable modes typical of a transport engine, the temperature of the cylinder and the cylinder head is maintained automatically. Thus, at low loads, the boiling of the coolant on the hot surfaces of cavity 1 does not develop, and the difference between the densities of the liquid in the zones of cavity 7 and channel 11 is not enough to overcome the hydraulic resistance of channels 8-P, and to sufficiently heat the surrounding atmosphere external surfaces of the cylinder and cylinder head. As the engine load increases, the temperature of the vapor phase of the cooler in the zone of cavity 7 increases, the difference in densities in the zone of cavity 7 and channels 11 increases, and circulation of fluid through channels 8-11, which have significant fins on external surfaces, starts. The intensity of heat transfer from the parts to the circulating fluid and from the fluid to the surrounding medium increases as the load increases, thus increasing the amount of heat removed from the engine by the cooling system.

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FIG. 2

Claims (1)

57) TWO-STEEL CARBURETARY ENGINE OF LIQUID COOLING on auth. St. No. 1229391, characterized in that, in order to increase engine durability by more evenly distributing the temperature field across the cylinder and its head, at least two communicating channels are made in the cylinder and its head, the channels of the cylinder head being connected in the upper part of the cavity and the cylinder channels to the bottom of the cavity.