Internal-combustion engines – Cooling – Liquid coolants other than water and water treatment
Patent
1990-05-24
1991-11-19
Kamen, Noah P.
Internal-combustion engines
Cooling
Liquid coolants other than water and water treatment
123 4182R, 123193CH, F01P 300
Patent
active
050657070
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an oil-cooled cylinder head for a four-stroke internal combustion engine in which combustion occurs with little heat loss. Combustion takes place in a hot core and this core is surrounded by an insulating layer of excess air. Accordingly, the cylinder wall requires no external cooling, at least not below the area of the piston which serves as the ring carrier.
The subject of the present application is thus an improvement for the cooling system of a four-stroke internal combustion engine, especially the cylinder head. Among other things, the improvement brings about savings in fuel by reducing cooling requirements, decreases frictional losses between the piston and the cylinder wall, and eliminates thermal stresses.
The subject of the present invention is also a conversion kit for modifying water-cooled or air-cooled internal combustion engines on the market so that the improved thermal characteristics of an oil-cooled engine can be imparted to the same.
Improvements in the thermal characteristics of an engine cannot be achieved by cooling the parts adjacent to the combustion chamber as intensively as possible. Nevertheless, this has been the conception for the past several decades. This is indicated by the use of water as the usual cooling medium in practice. Due to its high heat capacity, water constitutes a reliable agent for the optimal removal of heat from the engine. However, this reliability is associated with the drawback that a separate cooling circuit, including flow channels in the cylinder head and motor block, must be provided. Thus, although water is not to contact functional parts of the engine and is inherently foreign to engine operation, it has been employed because of its cooling efficiency. As a result, instead of designing the engine for optimum operation, the overall thermal characteristics of the engine were based on the properties of water as a cooling agent; the effect on the development of engine components was, for example, that strongly heat-conducting materials such as aluminum were used for pistons, cylinders and even cylinder heads so that the intense cooling action of the water could penetrate to the interior of the engine.
Thermal cracks in the material are only one phenomenon which demonstrate the contrast between engine operation with hot gases and abrupt cooling of the material to the temperature of the cooling water. A contributing factor here is that the possibility of rapid heat removal leads to combustion processes whose performance is based on heat removal through the walls of the combustion chamber, that is, all thermally uniform combustion processes in which the entire quantity of air is mixed with the fuel and the walls of the combustion chamber are subjected to a flame upon combustion. This includes chamber processes which are associated with significant heating of the combustion chamber walls.
To the present, the drawback of this cooling concept is that up to a third of the energy supplied is lost to the cooling water and, from there, must be transferred to the atmosphere via heat exchangers. It is no different in engines with external air cooling where numerous cooling ribs are provided in an attempt to make the engines as effective as a water-cooled engine with respect to heat removal. Experiments with oil cooling, which are carried out now and then, also function in accordance with this principle: it is attempted to compensate for the lower heat capacity of oil compared to water by increasing the flow quantity and the sizes of the oil cooling chambers with reference to water-cooled engines. From the point of view of rapid heat removal, oil cooling cannot compete with water. Since the oil pumping devices must be enlarged, the operating efficiency of the engine is reduced.
It would also be incorrect to incorporate ceramic parts in a combustion chamber as a result of a development which had heat removal as its Primary Seal. Although the intent is to provide heat insulation since, the walls of the combustion c
REFERENCES:
patent: 4573436 (1986-03-01), Owens
patent: 4854276 (1989-08-01), Elsbett et al.
Elsbett Gunter
Elsbett Klaus
Elsbett Ludwig
Kamen Noah P.
Kontler Peter K.
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