Marine propulsion – Means for accomodating or moving engine fluids – Cooling for engine
Reexamination Certificate
2001-12-14
2003-06-17
Sotelo, Jesus D. (Department: 3617)
Marine propulsion
Means for accomodating or moving engine fluids
Cooling for engine
Reexamination Certificate
active
06579136
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed generally to systems and methods for inhibiting corrosion, freezing, and other detrimental results caused by water within a cooling system of a liquid-cooled engine, and more particularly, to systems and methods for containing and delivering protective materials to raw water passageways of a cooling system in an open loop portion of a liquid-cooled marine engine.
2. Background
Combustion engines generate power by controlling multiple explosions of a combustible fuel. This process typically produces rotational motion and generates heat as a by-product, which is dissipated in various ways. Some engines dissipate the heat by-product using convection and air flow across fins and other surfaces. Other engines dissipate the excess heat generated through an exchanger using liquid, usually a water mixture. Specifically, water-based liquid is circulated through passageways located around the exterior portions of the engine proximate to the combustion chambers containing the pistons. Liquid-cooled combustion engines are typically either closed loop or open loop systems. Closed loop systems use recirculating liquids that are internally contained within the cooling system. The liquids used within a closed loop system absorbs heat generated by the engine and is cooled through a heat exchanger, such as a radiator. Open loop systems draw cooling liquids from an outside source, circulate it around the head of the engine and then discharge the heat laden water, normally back to the environment. Thus, only raw liquid is typically used within an open loop system.
Open loop liquid-cooled combustion engines are commonly used in the marine industries. Outboard engines, inboard/outboard engines, and inboard engines have all traditionally used liquid-cooled cooling system, and many marine engine designs have used open loop systems. In open loop systems, the engine draws raw water from the body of water in which the carrying vehicle is operating and circulates that raw water through the cooling system. As a result, engines cooled in such a way are subjected to water that includes contaminants and corrosive materials. For instance, when marine engines are operated in salt water marine environments, the engines circulate salt water through the cooling systems. As is well known, salt water is an extremely corrosive fluid that can severely limit engine life and efficiency.
There are also closed loop liquid-cooled marine engine designs, but they typically do not totally eliminate the risks associated with the open loop, raw water systems. These systems can be likened to those found in automobiles in which a water-based fluid is circulated through cooling channels in the combustion engine where heat is picked up, and then passed through the radiator where the heat is released to the relatively cooler air passing over the fins of the radiator. Where the marine version of the closed loop cooling design normally departs, however, is that instead of an air-exposed radiator, a heat exchanger is used which is exposed to a raw water, open loop conveyor or passageway. In this way, heat from the closed loop is transferred to the raw water at the heat exchanger. As described above, the raw water is then discharged back to the environment. Implementation of a closed loop design does not normally eliminate an open loop arrangement in a marine engine, but it does minimize and limit the exposure of the engine's components to the corrosive raw water. That being said, even closed loop cooling arrangements on marine vessels will typically have an associated open loop system that is susceptible to the corrosive effects that raw water presents and which should be minimized through flushing procedures.
The corrosive nature of salt water has been traditionally addressed by using fresh water to flush the cooling system of a marine engine after is has been used in salt or brackish water. The conventional flushing process includes circulating fresh water through the cooling passageways of the liquid-cooled engine. This process is preferably performed soon after the engine has stopped running so that the salt water will be immediately removed from the cooling system, but especially before the water has evaporated leaving salt crystals on the inside surface of the passageways of the cooling system.
A conventional process for flushing outboard engines and inboard/outboard engines is to connect a fresh water source to the raw water intake ports located on the lower units of these marine power plants. The fresh water source can be a municipal water system, a well, or other system, and can be coupled to the raw water intake ports using a flush device that is commonly referred to as “ear muffs” or “rabbit ears.” The flush devices generally have a wishbone shape with form-fitting cups attached to each end of the arms of the device forming the wishbone shape of the device. The cups are made of a pliable material and are sized to cover the raw water intake ports on the lower unit. Typically, one of the cups is in fluid communication with a standard female garden hose fitting adapted to be connected to an end of a garden hose. During use, the cups are fitted over the raw water intake ports of the lower unit and a garden hose is connected to the device. The engine is flushed by first turning on the water and allowing the water to flow up to the raw water intake ports. The engine is started and allowed to run for a period of time normally ranging from about 5 to 7 minutes.
For engines equipped with thermostats within the cooling system, it is necessary to run the engine for a time period sufficient to allow the thermostat to open so that fresh water actively flows throughout the entire cooling system. Because the boat carrying the engine has often been trailered to a second location away from the body of water where it was operated, the engine is often beginning the flushing process in a “cold” state. If so, short flushing periods will be inappropriate because in the beginning of the flushing process the fresh water only has the possibility of reaching essentially as far as the thermostat, with very little flushing water flowing therebeyond until the thermostat opens.
After a successful flushing period, the engine is stopped and the water flowing into the flushing device is then shut off. The flushing device is removed and the engine is assumed ready to be stored.
The flushing device described above is only suitable for use when the boat carrying the engine is out of the water. Otherwise, if this conventional flushing device is used while the boat remains in the water and, more importantly, while the lower unit of the power plant remains in the water, it is almost certain that corrosive raw water will seep into the raw water passages before, during and after the flushing process, thereby defeating the protective flushing measures.
While this flushing device circulates fresh water throughout the cooling system of a marine engine, it does not remove all of the salt water from the cooling system. Instead, there exist areas within most cooling systems that produce eddies when water is circulated through the engine. These eddies prevent some of the salt water from being removed from the cooling system. Thus, flushing an engine does not completely protect the open loop portion of a liquid-cooled marine engine from the corrosive action of salt water. Still further, there is no guarantee that the water used in the flushing process is itself absolutely pure and free of corrosive components.
Therefore, conventional flushing procedures at best partially protect a marine engine from salt water and also requires that the boat operator actively participate in the flushing process. Specifically, the operator must take the time to place the flush device on the lower unit and run the engine for the specified time period. While this preventive maintenance increases the life of a marine engine, many boat operators fail to flush their engine for any number of reasons such as lac
Galway Robert
Hahn Douglas
Savineau Cedric
Skrzypek Mark
Stone, II Carl
AB Volvo Penta
Howrey Simon Arnold & White , LLP
Sotelo Jesus D.
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