Internal-combustion engines – Means to whirl fluid before – upon – or after entry into... – Having multiple oxidant inlet means
Patent
1982-02-25
1984-11-27
Lazarus, Ira S.
Internal-combustion engines
Means to whirl fluid before, upon, or after entry into...
Having multiple oxidant inlet means
123193H, 123315, 123666, F02B 2304
Patent
active
044845502
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an internal combustion engine with at least one combustion chamber produced in a cylinder head. It is possible to pass a fuel-and-air mixture to the said combustion chamber via two inlet valves arranged in the cylinder head and for the exhaust gases to be discharged from the combustion chamber through two exhaust valves arranged in the cylinder head, whereby the invention also provides for a method of constructing such a combustion chamber so as to enable simple production of internal combustion engines in accordance with the invention.
In the technology of internal combustion engines there is increasing emphasis on the requirement of improving and rationalizing the combustion process in a internal combustion engine. A method of bringing this about consists in improving the volumetric efficiency of the engine, which may be regarded as a measure of how well the combustion chamber can be filled with a fuel-air mixture.
Another method consists in improving the thermal efficiency of the engine, which is a measure of how mell the fuel supplied to it is utilized. The thermal efficiency increases with the compression ratio of the engine and also increases as the fuel supplied is distributed more uniformly within the combustion chamber, enabling even combustion.
The volumetric efficiency can be improved by improving the gas exchange in the combustion chamber, which can be brought about by providing the engine with larger and/or more valves than the two valves per cylinder normally provided in conventional internal combustion engines. To this end it is known how to design engines with four valves per cylinder, with two valves operating as inlet valves and two valves as exhaust valves. By providing four valves the principal aim consists in obtaining a much power as possible from the engine, and such engines have therefore been used mainly in racing cars and other applications, where the engines are made to operate at high speeds.
With four-valve-engines it is known how to design the cylinder head of a cylinder in accordance with a so-called "pent roof"-design. This signifies that the valves and the valve seats are arranged in pairs in two planes that are inclined in relation to one another, with the planes forming a longitudinal crestlike ridge. Such a design is efficient when operating at high engine speeds, since the gases enter the engines at a high velocity thus enabling efficient mixing of the fuel with the incoming air and also distributing the fuel-air mixture in the combustion chamber in a fairly uniform manner. At lower operational speeds the velocity of the incoming gases is reduced, thus causing a poorer distribution of the fuel-air mixture in the combustion chamber. This in turn means that more fuel must be supplied than is theoretically necessary in order to maintain within the combustion chamber a mixture ratio which will not give rise to uncontrolled combustion events, i.e. knocking. As a result the thermal efficiency of such an engine is poor at low and medium operating speeds.
The said "pent roof"-design also necessitates a complicated and hence expensive method of production, and this is that reason why the design has not been utilized to any major extent in connection with the series production of vehicle engines.
With a view to reducing the costs entailed in the production of four-valve-engines it is known from U.S. Pat. No. 3,633,577 how to design a combustion chamber in a cylinder head with two oblong cavities. Such a design enables the combustion chamber to be produced by milling, subject to the condition that during this process the cross-section constitutes the section of the respective cavities of the combustion chamber in one direction. In the other oblong direction the milling cutter forms the respective ends of the two cavities so that they correspond with the arc-shape of the cutter. The design requires the volume of the space in the cylinder head to be relatively large so as to be capable of accommodating sufficiently large valves. This entails difficul
REFERENCES:
patent: 3094977 (1963-06-01), Sampietro
patent: 3424143 (1969-01-01), Apfelbeck
patent: 3633577 (1972-01-01), Piatti
patent: 4106444 (1978-08-01), Deutschmann et al.
patent: 4363300 (1982-12-01), Honda
Gadefelt Bengt G.
Saaf Lars L.
Bailey R. S.
Lazarus Ira S.
Saab-Scania Aktiebolag
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