Fuel composition containing molybdenum source and metal-containing detergent, and its use in two-stroke engines

Abstract

A fuel composition, and a method and an apparatus for combusting it in a two-stroke engine, in which molybdenum introduced from the fuel will interact with alkaline earth metal originating from a detergent or other co-ingredient of the fuel in the combustion products to increase detergency without increasing the level of alkaline earth metal or compounds present in the fuel or combustion products thereof. In this manner, the engine operates more cleanly and efficiently without increasing the risk of harmful alkaline earth materials and compounds thereof blocking and poisoning catalysts, sensors and / or automotive on-board diagnostic devices, and it can lead to improved durability of exhaust after treatment systems.

Description

[0001] This application claims the benefit of priority under 35 U.S.C. .sctn.119 to European patent application serial no. 03252539.6, filed Apr. 23, 2003, the entire disclosure and contents of which are incorporated herein by reference for all purposes.Description[0002] 1. Field of the Invention[0003] The present invention relates to a fuel composition for two-stroke engines containing a molybdenum source and an alkaline earth metal-containing detergent compound, and a method of its use for delivering molybdenum and the alkaline earth metal-containing detergent into a fuel combustion system and to the exhaust therefrom of a two-stroke engine. By the present invention, the molybdenum increases the detergent action of an alkaline earth metal detergent compound included in the fuel composition. This enhancement permits use of lower yet still effective levels of metal-based detergent in the fuel composition, and thus lower levels of alkaline earth metals are present in the fuel composi...

AI Technical Summary

Benefits of technology

[0011] The addition of molybdenum compounds together with or without a metal-containing detergent to crankcase lubrication oils has been described in the patent literature. U.S. Pat. No. 6,300,291 describes a lubricating oil composition for use in an engine crankcase to improve low temperature anti-wear performance and fuel economy containing an oil of lubricating viscosity, at least one calcium detergent providing calcium in an amount of 0.058 to 0.58 wt. %, at least one soluble molybdenum compound providing Mo in amount of up to 350 ppm Mo, at least one nitrogen containing friction modifier, and at least one zinc dihydrocarbyldithiophosphate compound providing phosphorous in amount of about 0.1 wt. %, where the composition has a NOACK volatility of about 15.5 wt % or less.

Problems solved by technology

However, the fuel-lubricant mixtures used as the combustion fuel in these two-stroke combustion engines also tend to form combustion products with relatively higher amounts of unburned fuel components, particulate matter, or other pollutants than when combusted in four-cycle engines of comparable power.

However, among other things, the above-mentioned patent references fail to describe any recognition that certain metal-based detergents, if used as described therein, can be a source of contaminants having a detrimental effect on the combustion system's catalysts, after treatment system, and / or other emission control systems.

The resulting reduced level of alkaline earth metal translates into the reduced presence of alkaline earth metal by-product compounds, such as sulphates thereof, in the exhaust stream such that less blocking and other contaminant-related problems occur on exhaust emissions after-treatment devices and / or control devices.