Internal combustion engine

Details Internal combustion engine Internal combustion engine

1998-11-06

2000-04-25

McMahon, Marguerite

Internal-combustion engines

Charge forming device

Heating of combustible mixture

123549, F02M 3118, F02M 2900, F02M 5302

Patent

active

060531533

DESCRIPTION:

BRIEF SUMMARY
PRIOR ART

The invention relates to an internal combustion engine.
In such an engine, to reduce the hydrocarbons contained in the exhaust gas (raw HC emissions), the combustion cylinders of the cold engine upon cold starting and during the then ensuing warmup are supplied centrally, via the intake tube, with fuel vapor mixed with combustion air. As a result, combustion in the combustion cylinders proceeds in a highly stable and largely homogeneous way, and HC emissions are reduced drastically. In normal driving, conversely, the fuel vapor admixture is dispensed with, and the fuel is delivered to the combustion cylinders in the known way via the injection valves.
In one known method for mixing fuel vapor with combustion air in the central intake tube of the internal combustion engine (Charles Aquino and Williams D. Plensdorf, "An Evaluation of Local Heating as a Means of Fuel Evaporation for Gasoline Engines", International Congress and Exposition, Detroit, Michigan, Feb. 24-28, 1985, SAE Technical Paper Series, 860 246, 1986), so-called swirl vanes disposed downstream of the throttle valve create turbulence paths in the intake tube, into which paths fuel is injected largely tangentially into the intake tube by means of two injection valves disposed upstream of the throttle valve. The fuel spray introduced is carried by the turbulence along heated surfaces downstream of the swirl vanes in the intake tube and is evaporated there. The resultant fuel vapor mixes intensively with the now-turbulent combustion air, thus creating a largely homogeneous fuel-air mixture. The swirl vanes built into the intake tube for creating turbulence are disadvantageous, however, in the sense that they markedly throttle the aspirated air and thus lead to a considerable loss in power and efficiency.


ADVANTAGES OF THE INVENTION

The internal combustion engine according to the invention, and the method of the invention employed in this engine, have the advantage over the prior art that for the intensive mixing of fuel vapor and combustion air, no built-in fixtures in the intake tube that reduce the power and efficiency are provided; instead, the turbulence paths that are naturally present in the intake tube and that unavoidably develop because of the intake tube and/or throttle valve geometry, which is already determined by other considerations, are utilized to make the fuel vapor generated outside the intake tube turbulent. Such turbulence paths develop at structurally dictated discontinuities of the intake tube wall and in particular at the edges of the throttle valve. Compared with the intake tube without fuel vapor admixture for cold starting and warmup, no additional flow resistances develop as a result of the fuel vapor admixture; compared with the known central fuel vapor admixture, along with this advantage of improving power and efficiency, the structural expense in the intake tube is reduced. Because the fuel vapor is generated outside the intake tube and introduced into the air eddies, instead of the introduction of fuel spray with ensuing evaporation along heated surfaces in the intake tube, a very homogeneous mixture formation is achieved even before the connections where the intake tube branches to lead to the individual combustion cylinders, and as a result an exactly identical quality of the fuel-air mixture for the individual combustion cylinders is assured. This in turn leads to identical operating conditions for all the combustion cylinders, to a reduction in wall film development in the combustion cylinders, and to stable combustion in the combustion cylinders. The expulsion of hydrocarbons with the exhaust gas is reduced drastically, and the catalytic converter can already begin converting very early after the engine has started.
Advantageous refinements of and improvements of the internal combustion engine disclosed are possible with the provisions recited herein.
Introducing the fuel vapor into the "natural" turbulence paths in the intake tube can be achieved by suitable geometrical definitions of the orific

REFERENCES:
patent: 2322991 (1943-06-01), Wunsch et al.
patent: 3618579 (1971-11-01), Varran
patent: 4329964 (1982-05-01), Morris
patent: 5343848 (1994-09-01), Birch et al.
patent: 5408973 (1995-04-01), Spangjer
patent: 5711282 (1998-01-01), Lang et al.

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