Internal-combustion engines – Cooling – Air-cooled
Reexamination Certificate
2002-06-03
2003-09-30
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Cooling
Air-cooled
C123S041690
Reexamination Certificate
active
06626134
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to engines, including but not limited to internal combustion engines used, for example, as source of power in propelling motorized vehicles. Specifically, the invention is directed to a cooling system for engines and components thereof as well as methods for producing the system.
BACKGROUND
Engines, especially internal combustion engines, produce significant amounts of heat during the course of their operation. Continued operation of an engine requires that the heat produced during its operation be transferred away from the engine at a high rate. This is especially true in with engines installed in vehicles which are operated at elevated ambient temperatures and higher elevations, or altitude. Another important factor is the availability of a cooling airstream or the lack thereof. To this end, engines are fitted with various cooling systems for transferring heat away from the engine. These cooling systems typically rely on a flow of fluid over or through the engine casing or engine components as a means of transferring heat from the engine to the environment. Failure to transfer heat away from the engine can result in a significantly reduced power output of the engine and in extreme conditions could lead to failure of the engine.
Many engines rely on air as the primary cooling agent and thus such engines are often referred to as being “air-cooled” engines. Such air-cooled engines are, for example, used extensively to power motorcycles, snowmobiles, light aircraft, and other vehicles where the weight and added complexity of a liquid-cooled engine is not desired or feasible. Air-cooled engines are also used extensively for engine powered lawn mowers as well as for engine powered gardening, construction, and wood sawing equipment.
In contrast, a liquid cooled engine will typically have a liquid such as water, ethanol, or other liquid which is circulated within internal passageways, or jackets, of the engine to remove heat generated by the engine. A liquid coolant circulative system can be either a closed system, such as radiator cooling system in an automobile which continuously recirculates a relatively small quantity of cooling fluid or an open system, such as a cooling system for boat engines which draw water in from the water in which the boat is operating and then merely discharge the water overboard after it has been passed through the boat engine.
Whether the engine is primarily air-cooled or primarily liquid- cooled, the engine will typically, but not always, consist of an engine casing, at least one cylinder or barrel structure encasing at least one reciprocating piston and a cylinder head. The cylinder head is mounted atop the cylinder and provides a combustion chamber as well as for housing intake and exhaust valve mechanisms if the engine is an “overhead valve” type of engine. If the engine is an “overhead cam” type of engine, the cylinder head will typically house at least one camshaft in addition to the valve train, or mechanism, in which the camshaft is an operative component. Additionally, an engine will often include a valve cover, if an overhead valve type of engine, or alternatively a cam cover if the engine is an overhead cam type of engine. There are of course other types and variations of the four-stroke type of engines just described, as well as other types of engines. One such engine is a two-stroke type of engine, which will typically include an engine casing, at least one cylinder encasing a reciprocating piston, and cylinder head having a combustion chamber. Unlike a four-stroke type of engine, the cylinder head of a two-stroke engine will normally not have any type of valve train or cam operated mechanism in the cylinder head itself.
Regardless of the specific type of air-cooled engine and regardless of how many cylinders, or how each cylinder is physically oriented with respect to another cylinder, i.e. inline, opposed, or whether in a V-arrangement, the engine is usually positioned to permit a flow of air over and about the engine, including at least some if not all of the previously mentioned sub-components of the engine during the operation of the engine.
To increase the rate of heat transfer to the ambient air generated by the combustion of fuel and air within the engine, or more precisely the heat generated within the cylinder and the cylinder head where such combustion takes place, at least the cylinder, or cylinders in a multi-cylinder engine, and the respective cylinder head, or cylinder heads, the engine is often fitted with a number of cooling fins which extend outwardly from the engine. Such cooling fins are usually extensively provided on the cylinder structure and cylinder head portions of an air-cooled engine, and often to a lesser extent on liquid-cooled engine as well in order to transfer heat away from the engine which is generated by the combustion of fuel and air. To provide additional cooling capability, it is not uncommon to provide cooling fins on the engine casing as well as on the valve covers, or cam covers, other sub-components and auxiliary components of the engine to enhance the transfer of heat generated by the engine to the surrounding environment which is usually the ambient air, but which could be another fluid as the term is used in the field of engineering. It is widely recognized within the art of constructing engines which employ cooling fins, that cooling fins serve to increase the effective surface area from which heat is transferred to the environment generated from within the engine and its associated components. With the increase in effective surface area provided by the cooling fins, the rate of radiative and convective heat transfer to the environment is increased. Such increase in cooling capability is further influenced by the number and size of the cooling fins which have been placed on various engine components to help better regulate the air exchange to produce a sought after cooling effect for the intended range of operation and conditions in which the engine will be subjected.
Although the art is replete with internal combustion engines having a wide variety of cooling fin arrangements, there remains a need within the art to provide a yet more efficient system of heat transfer from engines. Additionally, there is a need to provide a more efficient system of heat transfer from engines which is readily adaptable to air-cooled, liquid-cooled, four-stroke type, two-stroke type, or other type of engine and which is readily adaptable to any particular application in which a given engine is to be used, whether it be a motorcycle, aircraft, boat, or other motorized vehicle, and which is generally suitable for use with transferring heat energy generated from the operation of an engine.
There also remains a need with the art for an engine cooling system and method for making same that can be readily incorporated within the design of newly manufactured engines and related components or which can readily be retrofitted onto any engine and related components having cooling fins.
Furthermore, there is a need within the art for an engine cooling system and method for making same that is particularly suitable for incorporation within particular components of engines having at least one cooling fin, or similar structure thereon. Such engine components include, but are not limited to, engine casings, cylinders, cylinder heads, various inspection/access covers, valve, or rocker-arm, covers, cam covers, and other components which form, are attached, or otherwise associated with an engine.
There is also a need within the art for an engine cooling system and method for making same that is particularly suitable for incorporation within auxiliary components of engines, including but not limited to, heat exchangers such as oil coolers and liquid coolant radiators, and other components which may not necessarily be directly attached or directly form a portion of an engine.
DISCLOSURE OF INVENTION
The present invention provides an engine cooling system which provides an une
Benton Jason
TraskBritt
Yuen Henry C.
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