Patent Application
20110253074
The present invention relates to the control of locomotive engines and in particular to reducing emission levels of switch locomotives to comply with USEPA emission standards under 40 CFR Part 1033 regulations which became effective in January 2010.
USEPA emission standards under 40 CFR Part 1033 became effective in January 2010. These standards include:
Nitrogen oxides (NOx)=11.8 gms/bhp-hr;
Hydrocarbons (HC)=2.1 gms/bhp-hr;
Carbon Monoxide (CO)=8 gms/bhp-hr;
Particulate matter (PM)=0.26 gms/bhp-hr; and
Smoke opacity=30/40/50
The above standards are also known as Tier 0 plus standards.
Switch locomotives commonly use an Electro Motive Division (EMD) 645 series engine. The 645 series engines are a family of eight, twelve, sixteen and twenty cylinder 45 degree Vee two stroke diesel engines used as locomotives, marine, and stationary engines. Each engine includes the same bore and stroke producing 645 cubic inches per cylinder, and include a roots blower or a turbocharger. The 645 series engines have been replaced by 710 series engines, but are still in use, for example, in the switching locomotives.
Two stroke diesel engines include exhaust valves in the head(s) and intake ports low in the cylinder walls which are covered by the pistons during most of an engine cycle and briefly uncovered to allow air to enter the cylinder. The exhaust valves are opened by a cam(s) when the piston nears Bottom Dead Center (BDC) at the end of the power stroke and close after the intake ports are uncovered by the piston, resulting in both the exhaust valves being open and the intake ports uncovered at the same time. The two stroke diesels require a supercharger to force air through the intake ports and into the engine because there is no vacuum to draw air into the cylinder. The piston again covers the intake ports shortly after beginning the compression stroke. Fuel is injected into the engine near Top Dead Center (TDC) and is ignited by heat in the cylinder at the beginning of the power stroke. Such diesel engines would be less efficient than gasoline engines, except for the fact that because the diesel fuel is not in the cylinder during the compression stroke, a higher compression is useable with a diesel engine than a gasoline engine, and the thermal efficiency of the engine increases with compression ratio.
Various methods have been exercised to reduce the emissions of locomotives using the EMD 645 series engines. Unfortunately, while known methods address some of the Tier 0 standards, the known methods have failed to address all of the standards.
Various aspects of the present invention address the above and other needs by providing a locomotive diesel engine emissions control suite which may be applied to existing in-use Electro Motive Division (EMD) 645 series engines to meet the USEPA emission standards under 40 CFR Part 1033 regulations. Switch locomotives are now required to comply with USEPA emission standards under 40 CFR Part 1033 regulations. The locomotive diesel engine emissions control suite includes retarding fuel injection timing and heating the diesel fuel which allows the switch locomotives to meet the 40 CFR Part 1033 regulations.
In accordance with one aspect of the invention, there is provided an emissions control suite which includes retarding fuel injection timing and heating the diesel fuel. Retarding the fuel injection timing reduces peak temperatures during combustion which in turn reduces production of Nitrogen oxides (NOx) but also increases emissions of Particulate Matter (PM), Carbon Monoxide (CO), and Hydrocarbons (HC) in the exhaust. Unrelated efforts by the present inventors to reduce the smoke in diesel exhaust by pre-heating the diesel fuel showed an unexpected reduction in PM, CO, and HC. Such heating of the diesel fuel is expected to increase combustion temperature and thus NOx, but unexpectedly, a substantial increase in fuel temperature, from 75 degrees Fahrenheit to as much as 140 degrees Fahrenheit did not defeat the reduction in NOx provided by the retarded fuel injection timing, but did reduce PM, CO, and HC emissions to satisfy 40 CFR Part 1033 regulations. Further experiments showed that an unexpected synergistic combination of two degrees of fuel injection retarding and fuel heated from a typical 95 degrees Fahrenheit to approximately 140 degrees Fahrenheit resulted in meeting the 40 CFR Part 1033 regulations. The temperature of the heated diesel fuel must be carefully controlled to not exceed approximately 140 degrees Fahrenheit which is approaching the flash point of the diesel fuel.
In accordance with yet another aspect of the invention, there is provided an emissions control suite which reduced emissions in diesel engines having a compression ratio between 14.5 to 1 and 16 to 1, and as high as 17.4 to 1 or higher.
The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein:
Corresponding reference characters indicate corresponding components throughout the several views of the drawings.
The following description is of an embodiment presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention, and other embodiments derived by those skilled in the art are intended to come within the scope of the present invention. The scope of the invention should be determined with reference to the claims.
Reduction of engine emissions have proven to be very difficult due to the complex nature of combustion in engines. Methods have generally consisted of trial and error and lack accurate models capable of predicting results. Further, emissions reduction is generally a non-linear multi-dimensional problem including the interaction of fuel control, air intake control, engine bore and stroke, combustion chamber design, operating temperatures, and other design and operation parameters. The overall environment of engine emissions control thus presents a complex problem with few obvious solutions when a single parameter is varied, and virtually no obvious solution when multiple interacting parameters are varied.
An example of an emissions control suite 10 according to the present invention is shown in
The fuel injection retard element 12 comprises retarding the fuel injection timing to delay the injection of diesel fuel to reduce the peak combustion temperature. NOx is created when nitric oxide (NO) reacts with oxygen (O2) to create nitrogen dioxide (NO2). The lower peak combustion temperature reduces the chemical reaction reducing the production of NOx. Unfortunately, retarding the fuel injection timing also increased the emissions of particulate matter (PM), Carbon Monoxide (CO), and Hydrocarbons (HC). Preferably, the fuel injection timing is retarded by approximately two degree of crankshaft rotation to obtain the desired reduction in NOx. For example, a common fuel injection timing of four degrees Before Top Dead Center (BTDC) is preferably retarded to two degrees BTDC to delay the injection two degrees of crankshaft rotation.
There were no obvious methods for reducing the increased PM, CO, and HC in the diesel engine exhaust. However, an independent effort was underway to reduce smoke in the exhaust. One approach to smoke reduction which was tried was to heat the diesel fuel to provide more complete combustion. The engine exhaust was being monitored as part of the test, and an unexpected reduction in PM, CO, and HC was observed. Bases on these unexpected results, further tests were performed with different levels of fuel heating and a successful combination for fuel injection retard and fuel heating was discovered which satisfied the 40 CFR Part 1033 regulations.
A diesel engine 34 including the emissions control suite 10 according to the present invention is shown in
No immediate solution to the increased PM, CO, and HC emissions resulting from retarding fuel injection timing was known, but an unrelated parallel effort was underway to reduce diesel engine smoke. One approach to reducing smoke which was tested was heating the diesel fuel to improve combustion. An unexpected result of heating the diesel fuel was that PM, CO, and HC emissions were reduced. Once this reduction was identified, additional experiments were performed with varying fuel injection retarding and fuel heating. Test results eventually showed that in various embodiments of the present invention two degrees of fuel injection retarding coupled with heating the fuel to between 120 and 140 degrees Fahrenheit, and preferably near the 140 degrees Fahrenheit flash point of the diesel fuel, provided consistently good results meeting the 40 CFR Part 1033 regulations.
A diagram of a preferred heat diesel fuel element 14 of the emissions control suite 10 is shown in
The flow control valve 58 is preferably a powered 3-way thermostatic valve which includes internal temperature regulating features to control the combining the heated fuel flow 50b with the bypass flow 60 to control the temperature of the heated fuel flow 26′. An example of a suitable flow control valve 58 is a AMOT self powered 3-way Thermostatic Valve with a target temperature designed into the valve.
A diagram of a second fuel heating element 40a of the emissions control suite according to the present invention is shown in
The amount of fuel injection timing retard and fuel heating disclosed above is based on results obtained for a limited variety of diesel engines. Other diesel engines include different types and methods of forced induction which often affect the temperature of air entering the engine and other engine parameters. As a result, variations to the amount of fuel injection timing retard and fuel heating disclosed here for the 645 series engines, to obtain similar reductions in emissions in other diesel engines, are intended to come within the scope of the present invention.
Additional engine modifications may enhance engines including the locomotive diesel engine emissions control suite. For example, the use of low oil consumption cast iron or stainless steel ring sets may be used to reduce oil consumption. Additionally, plateau honing the liners (thereby increasing the bearing area of the liner while maintaining oil retention) and plating the pistons with tin have shown potential advantages.
While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.
