Acid-neutralizing filter

Liquid purification or separation – With means to add treating material – With distinct reactor tank – trough or compartment

Reexamination Certificate

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C210S167150, C210S209000, C210S501000, C123S1960AB, C184S006240

Reexamination Certificate




This invention pertains to filtering and treating systems for lubricating systems. More particularly, the invention relates to an oil filtering and treating system for the removal of impurities and acids from the oil system of a gasoline or diesel engine.
Heavy-duty diesel engine life, or time to rebuild, has historically been linked directly to piston ring, cylinder liner or crankshaft bearing life. Engine design parameters require that these engine components be hydrodynamically lubricated, i.e., operate with a film of lubricant separating these engine components from associated metal surfaces. Consequently, the principle mechanism associated with piston rings, cylinder liners and crankshaft journal bearings wear is not metal-to-metal contact or frictional wear. The primary diesel engine wear mode influencing engine life is corrosive wear caused by sulfur and nitrogen containing acids formed during the diesel fuel combustion process. One estimate is that more than 70 percent of heavy-duty diesel engine wear is caused by combustion acid metal corrosion.
Control of diesel engine corrosive wear has historically been accomplished through inclusion of basic or alkaline chemicals within the engine oil that is utilized to form the hydrodynamic lubricant film. These alkaline components rapidly neutralize or solubilize combustion acids upon contact with the acid molecules. The effectiveness of the corrosive wear control is entirely dependent upon the probability of the acid being neutralized by alkaline oil components prior to contact of the acid with engine metal surfaces resulting in corrosive wear. The amount of engine corrosive wear can typically be monitored through the use of oil analysis where cylinder liner wear is associated with iron parts per million (ppm) level in the engine oil. Piston ring wear is monitored by chromium levels and crankshaft bearing wear is reflected by lead levels in the oil.
The corrosive wear process begins in the diesel engine combustion chamber where the hydrocarbon diesel fuel containing sulfur compounds is combusted in the presence of oxygen and nitrogen. The hydrocarbon fuel is converted to principally carbon dioxide and water, creating extremely high gas pressures, which push down on the top of the piston to produce engine power. Also produced are SO
and NO
compounds, which rapidly react with the water released during fuel combustion yielding primarily sulfuric acid and nitric acid. These acids reach engine metal surfaces by direct contact in the cylinder bore or as blow-by gases as a normal part of engine operation. The hydrodynamic lubricant film present in the piston ring belt zone will also transport acid molecules throughout the engine as the lubricant is constantly circulated.
Combustion acid neutralization is completed using a simple acid-base reaction where metal carbonates carried as alkaline components within the lubricant directly react with sulfuric and nitric acids. The effectiveness of corrosive wear control is totally dependent upon the probability of these metal carbonates coming in contact with the acid molecules before these same molecules contact engine metal surfaces. Another factor influencing the rate and efficiency of acid neutralization is acid solubilization within the lubricant by another oil additive classified as an ashless dispersant. Dispersants are long chain hydrocarbon polymers, which are functionalized by terminating the polymer chain with a functional group generally containing basic nitrogen. Dispersants will rapidly complex with combustion acids dispersing or solubilizing them within the lubricant for transportation to a metal carbonate where the acid is converted to a neutral metallic salt. The combined efficiency of dispersant acid complexing and metallic carbonate acid neutralization controls the rate of engine wear.
Overbased or alkaline metallic detergents have been widely utilized as metallic carbonate carriers in diesel engine oil compositions. Calcium and magnesium sulfonates and phenates account for the majority of the detergents utilized to formulate diesel engine oils. Overbased detergents are produced by incorporating extra calcium or magnesium within a physical structure called a detergent micelle. For example, alkylbenzenesulfonic when reacted with calcium hydroxide and blown with carbon dioxide during the reaction process will produce an overbased calcium sulfonate. The extra metal or calcium present in the detergent micelle structure is calcium carbonate surrounded by oil solubilizing calcium sulfonate detergents. This physical structure circulating within the oil delivers the calcium carbonate to the combustion acid molecules for acid neutralization.
Ideally, there should be no limit to the amount of alkaline detergent incorporated within a diesel engine oil formulation; however, in reality, modem diesel engines can only tolerate a limited level of metallic detergents before metallic ash deposits cause piston ring sticking and exhaust valve guttering. These ash deposits are caused by pyrolysis of oil metal organo compounds, principally calcium and magnesium detergents.
Recognizing (1) most diesel engine wear is caused by acid corrosion, (2) the lubricant ash content is limited, and (3) newer diesel engine designs will incorporate exhaust gas recirculation where combustion acids will be concentrated and reintroduced into the engine, a system capable of neutralizing combustion acids without significantly altering diesel engine oil compositions would significantly reduce corrosive wear. This is especially true in the later half of an oil drain period when the lubricant's acid-neutralizing capability has been depleted.
The present invention is directed to a system for extending the normal operating life of a fluid circulation system such as an oil circulation system associated with a diesel engine. The system includes an apparatus for assisting in the removal of acids which accumulate in the fluid, such as an oil, that is pumped through the circulation system. By removing such acids, the useful life of the circulating fluid may be extended thus lowering the operating costs. Preferably, the system of the invention includes a canister through which some or all of the circulating fluid passes. Within the canister is an acid-neutralizing compound which reacts with the acids in the circulating fluid to neutralize the acids. Preferably, once the fluid circulates through the acid-neutralizing compound, the oil passes through a particulate filter prior to returning to the oil circulation system.
The apparatus for removing acids may be inserted into the full flow portion of the fluid circulation system or may be inserted into a bypass system. In either case, from a small portion up to all of the fluid being circulated may pass through the acid-neutralizing apparatus depending upon the desired acid neutralization rate.
An acid-neutralizing canister for an oil circulation system is provided according to the present invention. Preferably, the canister is a spin-on canister although other means of attachment may be used such as a bolt-on system. The canister includes an outer canister shell, an inner shell, a base plate and a spring to maintain the material in the inner shell in compression when the canister is assembled. More particularly, the canister may include a base plate, a canister shell having a closed end, an open end and a generally cylindrical sidewall therebetween, and an edge of the cylindrical sidewall secured to the base plate at the open end, an inner shell, and an acid-neutralizing compound in the inner shell for neutralizing acids in the oil circulated between an inner shell central port and inner shell peripheral ports.
The spin-on canister base plate according to the invention may include a central hub, an outer peripheral rim surrounding the hub, and a plurality of radially extending ribs connecting the hub and the rim. The base plate hub preferably defines a threaded central opening for spin-on


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