Adsorbent structures for removal of water and fuel contaminants in engine oil

Abstract

Devices and methods for removal of condensed, blow-by contaminants with small molecular dimensions from the circulating lubricating engine oil of internal combustion engines, including automotive engines, with a positive crankcase ventilation system are disclosed. These condensable blow-by contaminants include water, alcohols and hydrocarbons with preponderantly seven or fewer carbon atoms. A macroporous structure comprising alumino-silicate particles with micro-pores is at least partially immersed in the circulating oil. The micro-pores are sized to adsorb the small, condensed, blow-by, contaminant molecules but not the larger oil molecules. The particles may be multi-layered, with an inner layer adapted for adsorption of polar molecules. Adsorption is most extensive at lower oil temperatures and decreases as the oil temperature increases. Thus at low temperatures the contaminant molecules may be adsorbed, removed from the oil and temporarily stored in the micropores. At high temperatures some of the contaminants will desorb and be re-incorporated in the oil. The desorbed contaminants will be carried with the higher temperature oil into the engine crankcase where they may vaporize and be removed by the engine positive crankcase ventilation system.

Description

TECHNICAL FIELD[0001]This invention pertains to devices and methods for temporarily adsorbing water and fuel contaminants from lubricating oil circulated in automotive internal combustion engines. More specifically, this invention pertains to the use of suitably-located crystalline particulate materials to adsorb such contaminants from relatively cold engine oil to extend oil life and to minimize potential corrosive damage to engine components. The contaminants are later released from the oil, for removal from the engine, when the engine is operating and the oil is relatively hot.BACKGROUND OF THE INVENTION[0002]Diesel, gasoline, and alcohol fueled internal combustion engines find broad application in both motor vehicles and stationary applications like motor-generators.[0003]Many such engines use hydrocarbon-based, oil lubricating systems in which the oil is pumped during engine operation from an underlying reservoir, up and over the pistons, cylinder walls, inlet and exhaust valve...

AI Technical Summary

Benefits of technology

[0010]At lower engine oil temperatures some of these contaminants may condense and remain in the engine lubricating oil and contribute to reduced oil life and engine damage. These condensed, blow-by contaminants comprise molecules of significantly lower molecular weight than the hydrocarbons and additives present in lubricating oil, and accordingly have smaller molecular dimensions. In accordance with embodiments of this invention, such relatively small, contaminant molecules may be selectively adsorbed from the oil by micro-porous crystalline solids, for example, zeolites, which may have, or may be formed to have, nanometer-sized pores of predictable and uniform dimension. Suitable volumes of such adsorbent zeolite particles may be placed, for example, in the oil circulation path or in the oil reservoir so that the oil contacts the adsorbent particles. The zeolites may adsorb and temporarily remove water, alcohol or hydrocarbon fuel from relatively cold oil so that such condensed contaminants are not circulated over engine surfaces. Later, when the oil is suitably heated by engine operation, the contaminants desorb from the adsorbent particulate material into the hotter oil and the contaminants are then vaporized and removed from the engine by normal operation of the engine's PCV system.

[0013]Thus, the zeolites(s) and the PCV system cooperate to minimize any deleterious effects of the condensed blow-by contaminants. At low oil temperatures the zeolites(s) serve to separate the condensed contaminants from the oil by adsorbing the contaminants within their micropores. With increasing temperature, the zeolites(s) will desorb the contaminants from the micropores and release contaminants back into the oil, but the increased oil temperature will promote more extensive vaporization of these contaminants so that they may be removed by the PCV system.

[0016]The inner zeolite volume of the multi-layer zeolite particles may have particular affinity for polar contaminants such as water, methanol and ethanol. Thus, all contaminants will be accommodated in the outer layer of the multilayer particles, but the polar molecules will be drawn to the inner layer of each particle leaving the non-polar molecules occupying the outer layers. As noted previously, strongly hydrophilic behavior is observed in zeolites with low silica to alumina ratios, typically ratios of less than about 10 and preferably in ratios ranging from 1 to 3. Such a multi-layer configuration has benefit in ensuring that all classes of contaminants are sequestered in the multi-layer structure, minimizing the possibility that any one contaminant class will be disproportionately adsorbed.

[0017]Synthetic zeolites are generally prepared as small crystalline precipitates, usually by a sol-gel process. But individual precipitates may be agglomerated using a suitable binder to form readily-handled particles of substantially consistent size, for example about a millimeter or so. In both the first and second embodiments, it is preferred to further aggregate the particles to avoid introducing possibly abrasive particles into the vehicle oil circulation system. Hence the particles, with the aid of a binder material, may be bonded together to form a macroporous structure of micro-porous zeolite particles enabling easy entry of lubrication oil into the structure and thereby exposing the oil to a large surface area of the micro-porous zeolite particles to promote extensive interaction between the oil and the zeolite structure.

Problems solved by technology

At lower engine oil temperatures some of these contaminants may condense and remain in the engine lubricating oil and contribute to reduced oil life and engine damage.

As the oil temperature increases, adsorption of the contaminants becomes less favorable and some of the contaminants may be desorbed to again be incorporated in the oil.

With continued increase in oil temperature, yet further contaminant desorption will occur, the vapor pressure of the contaminants will increase and contaminant gasses and vapors will accumulate in the crankcase where they may be permanently removed by the PCV system.

Images