Optimized Fuel Management System for Direct Injection Ethanol Enhancement of Gasoline Engines

a fuel management system and engine technology, applied in the direction of liquid fuel feeders, machines/engines, electric control, etc., can solve the problems of non-uniform ethanol injection and delay of ethanol injection, and achieve the effect of facilitating increased engine efficiency, gasoline savings, and improved efficiency under driving conditions

US20100006050A1Inactive Publication Date: 2010-01-14MASSACHUSETTS INST OF TECH
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
Publication Date
2010-01-14
Estimated Expiration
Not applicable · inactive patent

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Abstract

Fuel management system for enhanced operation of a spark ignition gasoline engine. Injectors inject an anti-knock agent such as ethanol directly into a cylinder. It is preferred that the direct injection occur after the inlet valve is closed. It is also preferred that stoichiometric operation with a three way catalyst be used to minimize emissions. In addition, it is also preferred that the anti-knock agents have a heat of vaporization per unit of combustion energy that is at least three times that of gasoline.
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Description

[0001] This application is a continuation of U.S. patent application Ser. No. 11 / 758,157 filed Jun. 5, 2007, which is a continuation of U.S. patent application Ser. No. 11 / 100,026 filed Apr. 6, 2005, now U.S. Pat. No. 7,225,787 the contents of both of which are incorporated herein by reference.BACKGROUND OF THE INVENTION

[0002] This invention relates to an optimized fuel management system for use with spark ignition gasoline engines in which an anti-knock agent which is a fuel is directly injected into a cylinder of the engine.

[0003] There are a number of important additional approaches for optimizing direct injection ethanol enhanced knock suppression so as to maximize the increase in engine efficiency and to minimize emissions of air pollutants beyond the technology disclosed in parent application Ser. No. 10 / 991,774 set out above. There are also additional approaches to protect the engine and exhaust system during high load operation by ethanol rich operation; and to minimize cost, e...

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Embodiment Construction

[0015]Ethanol has a heat of vaporization that is more than twice that of gasoline, a heat of combustion per kg which is about 60% of that of gasoline, and a heat of vaporization per unit of combustion energy that is close to four times that of gasoline. Thus the evaporative cooling of the cylinder air / fuel charge can be very large with appropriate direct injection of this antiknock agent. The computer model referenced below shows that evaporative cooling can have a very beneficial effect on knock suppression. It indicates that the beneficial effect can be maximized by injection of the ethanol after the inlet valve that admits the air and gasoline into the cylinder is closed. This late injection of the ethanol enables significantly higher pressure operation without knock and thus higher efficiency engine operation than would be the case with early injection. It is thus preferred to the conventional approach of early injection which is used because it provides good mixing. The model a...