Internal-combustion engines – Igniters – Incandescent
Patent
1991-07-19
1992-09-15
Argenbright, Tony M.
Internal-combustion engines
Igniters
Incandescent
1231796, 219270, 431268, F02P 1900, F02P 2302
Patent
active
051468816
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
to an improved method of operating unthrottled internal combustion engines at compression ratios lower than required for diesel engines. Moreover, this invention relates to means for operating glow plugs in unthrottled engines at lower plug temperatures than would be required with non-catalytic glow plugs of the same size and geometry. In one specific embodiment, the plug temperature is provided with temperature determining means and electrical power is controlled to maintain the plug walls at a value determined by the engine speed and power output.
This invention also relates to catalytic glow plugs capable of igniting fuels at lower temperatures than a non-catalytic glow plug of the same size and shape.
2. Brief Description of the Prior Art
Existing diesel engines achieve a significantly higher thermal efficiency than conventional gasoline engines in automotive use and emit acceptable levels of carbon monoxide and light hydrocarbons. However, soot and nitrogen oxide levels are high and compression ratios are much higher than the optimum for maximum fuel economy. Moreover diesels are relatively hard to start as compared to automotive gasoline engines, even with electrically heated glow plugs, and require high cetane fuels. This is especially true of the lower compression diesels such as the large lower speed engines. With use of glow plugs, short plug life can be a problem particularly under operating conditions which require higher plug operating temperatures, such as cold starting at arctic temperatures.
As a means of improving cold starting performance of conventional high compression diesel engines with glow plugs, the use of catalytically self-heating glow plugs has been proposed (U.S. Pat. 4,345,555). Such self-heating plugs are said to maintain a preset plug temperature by exothermic catalytic reactions after termination of the initial electrical heating of the plug during starting. A self-heating plug is said to maintain a higher temperature than a non-catalytic diesel glow plug and is further said to maintain a temperature above that required for ignition of fuel by a non-catalytic plug. It is taught that the catalyst should comprise a porous carrier, presumably to achieve greater surface heating (it is well known that such porous supports provide a greater surface area for catalytic reactions than a non-porous support). Self-heating plugs can be expected to offer no improvement in plug life as compared to conventional glow plugs inasmuch as such self-heating plugs are said to maintain a higher temperature than conventional plugs. Plugs which are effective at lower plug temperatures would allow easier starting under adverseconditions and would enable starting lower ambient temperatures.
In addition to the above cited shortcomings, conventional diesels cannot be operated at low enough compression ratios for maximum efficiency and conventional diesels cannot efficiently utilize low cetane fuels such as methanol and gasoline. Although in-cylinder catalysts previously proposed can improve efficiency and reduce emissions of soot and nitrogen oxides, retrofitting of existing engines is not always economically feasible, especially with small automotive diesels.
Conventional spark ignition engines are typically less efficient than diesel engines in spite of operating in close appoximation to the constant volume combustion Otto cycle, a more efficient cycle than the diesel cycle. This lower efficiency is believed to result primarily from the throttling losses associated with the requirement for spark ignition. Spark ignition requires near stoichiometric fuel-air mixtures for flame propagation. To control power levels, the amounts of fuel and air must both be varied in step. This requires throttling of the inlet air with resultant loss of pressure energy. Octane limits of fuels typically limit compression ratios to below optimum levels. Operation of spark engines without throttling of the inlet air could result in an engine more efficient than the dies
REFERENCES:
patent: 4345555 (1982-08-01), Oshima et al.
patent: 4658772 (1987-04-01), Auth et al.
patent: 4896636 (1990-01-01), Pfefferle
LandOfFree
Method of operating I.C. engines and apparatus thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of operating I.C. engines and apparatus thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of operating I.C. engines and apparatus thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-730289