Internal combustion engine

Details Internal combustion engine Internal combustion engine

1991-03-26

1992-06-16

Wolfe, Willis R.

Internal-combustion engines

Charge forming device

Exhaust gas used with the combustible mixture

123571, 60275, 60278, 60311, F02M 2507

Patent

active

051217341

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention is based on an internal combustion engine, in particular a Diesel engine, of the generic type defined hereinafter.
In a known engine of this type (German Patent Document 30 11 580 Al), an exhaust gas recirculation line is connected to each exhaust pipe leading away from the cylinder, for the purpose of exhaust gas recirculation, and an exhaust gas throttle valve is disposed in the line in order to vary the free cross section of the exhaust gas recirculation line. Downstream of the exhaust gas throttle valve is the exhaust gas manifold, from which branch lines lead to each intake pipe. One passage control device, which is operated synchronously with the engine rpm, is disposed in each branch line. At the point where the branch line discharges into the intake pipe, a guide tube is inserted into the intake pipe and with it forms an annular conduit.
The branch line discharges into the annular conduit. The guide tube ends immediately upstream of the inlet valve. With this kind of exhaust gas recirculation apparatus, the emissions of nitrogen oxide in the exhaust gas are markedly reduced, and the amount of exhaust gas is well mixed with the fuel and air mixture.
In highly supercharged NKW engines, the use of an exhaust gas recirculation apparatus has previously been avoided, since engine wear increases from soiling, the exhaust gas counterpressure under heavy load is lower than the charge pressure of the charge air compressor, and charge air coolers and compressors become dirty, which markedly reduces their efficiency. Adherence to required exhaust gas limit values in terms of nitrogen oxide emissions is attained here by charge air cooling, high supercharging, and very late injection onset by the fuel injection pump. Because of the late injection onset, however, this adherence is achieved at the cost of an increase of about 10 to 20% in fuel consumption.


ADVANTAGES OF THE INVENTION

The engine according to the invention has the advantage that the surface of the exhaust gas recirculation apparatus exposed to the exhaust gas that reaches the air a aspirated by the cylinders is comparatively small and thus can be embodied such that it is protected against soiling and corrosion. The charge air cooler and the charge air compressor are not exposed to exhaust gas and thus cannot become soiled. Thus the engine can be designed as an NKW engine without the danger of soiling as a result of the exhaust gas recirculation. Because of the reduction in emissions attained by the exhaust gas recirculation, the onset of injection by the fuel injection pump can re-adjusted to earlier timing, so that by comparison with NKW engines with a very late injection onset, the fuel consumption drops markedly, with equally low nitrogen oxide emissions.
The exhaust gas recirculation is independent of the pressure drop between the exhaust gas pipe and the intake pipe. The removal of exhaust gas to the exhaust gas distributor is always assured. The exhaust gas turbocharger can be designed thermodynamically, or in other words with a higher charge pressure compared with the exhaust gas counterpressure.
The tangential delivery of the exhaust gas to the inlet valve causes pre-storage of the exhaust gas upstream of the inlet valve, even if the exhaust gas occurs in batches. Upon opening of the inlet valve, exhaust gas is aspirated first, and then fresh air with fuel. Mixing takes place in the cylinder. Uniform distribution and good combustion are thus assured.
Advantageous further features of and improvements to the internal combustion engine defined herein are attainable with the characteristics recited hereinafter.
Because of the connection with only one cylinder of the engine, the exhaust gas in the exhaust gas distributor occurs in batches. To attain uniform distribution of the quantities of exhaust gas to all the cylinders, in a further embodiment of the invention the end pipes are on the one hand dimensioned in such a way that an equally large quantity of exhaust gas flows into each intake pipe, and

REFERENCES:
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patent: 3512509 (1970-05-01), Daigh
patent: 4100734 (1978-07-01), Ozaki et al.
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patent: 4249382 (1981-02-01), Evans et al.
patent: 4303053 (1981-12-01), Etoh et al.
patent: 4475524 (1984-10-01), Eckert et al.
patent: 4788819 (1988-12-01), Henkel
patent: 4969446 (1990-11-01), Olsson et al.

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