Internal-combustion engines – Combustion chamber – Having squish area
Reexamination Certificate
1999-02-22
2001-03-13
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Combustion chamber
Having squish area
C123S432000
Reexamination Certificate
active
06199544
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to combustion chambers for internal combustion engines and more specifically to such chambers having one intake and two exhaust valves and including squish areas.
BACKGROUND OF THE INVENTION
A great many different intake and exhaust valve arrangements have been developed over the years for use in internal combustion engines, in particular for use in automobiles. Most such engines use one intake valve and one exhaust valve at each cylinder with a single spark plug. The prior art arrangements utilize a ratio of intake valve area to exhaust valve area of over 65%. A great deal of effort has gone into optimizing the sizing and placement of the valves, the shape of the combustion chamber and the like. Since there is a great need for improvements in automobile fuel efficiency while maintaining or improving performance, a wide variety of different valve and spark plug configurations and arrangements have been designed and tested. In some of these, multiple valves and spark plugs have been used.
An arrangement of four valves per cylinder, two intake valves and two exhaust valves, has been disclosed, for example, by Akana in U.S. Pat. No. 3,411,490. Today, a number of high performance automobiles use four valve systems, with one or more spark plugs. In these high performance automobiles, several spark plugs may be provided around the periphery of the combustion chamber with an additional spark plug centrally located. Manufacture and operation of these four valve, multiple spark plug engines is complex and expensive and requires complex computer control for efficient operation.
Weslake in U.S. Pat. No. 2,652,039 describes a complex cylinder head arrangement for an internal combustion engine having a wedge-shaped combustion chamber adjacent to the cylinder feeding into a cylinder chamber above the piston. The combustion chamber has an intake valve, an exhaust valve and a single spark plug. A second intake valve is provided in the cylinder chamber. A weak mixture of air and fuel enters the combustion chamber, combustion begins and a rich mixture enters through the cylinder chamber and adds to the original combusting mixture. This very complex system appears to have been unsuccessful and to never have been brought into production.
Another three valve system is described by Von Segern et al in U.S. Pat. No. 3,443,552. Here, a basically conventional cylinder head having a single intake valve and a single exhaust valve with a primary, conventional, combustion chamber is provided. In addition, a centrally located auxiliary chamber is located on the cylinder axis away from the cylinder in gas flow communication with the primary combustion chamber. The auxiliary chamber has a single intake valve and a spark plug. Combustion begins in the auxiliary chamber, spreads to the main combustion chamber where added fuel mixture is introduced. Again, this is a complex and cumbersome system that appears to have been found to be impractical.
Suzuki et al. in U.S. Pat. No. 4,742,804 discloses a number of combustion chamber configurations, including some having two intake valves and a single exhaust valve. However, this arrangement requires that the exhaust valve be considerably larger than each intake valve and provides for a localized deep recess in the piston head to receive the spark plug. The combustion chamber is in the piston, rather than in a space between a generally planar piston face and the head.
Thus, while a great number of different arrangements of multiple valves and/or multiple spark plugs have been designed, none have provided an optimum combination of structural simplicity, maximum fuel efficiency and highest performance. Despite the crowded nature of the automobile engine fuel and air introduction and exhaust removal art, there remains a continuing need for improvements providing greater overall efficiency at lowest cost.
It is, therefore, an object of this invention is to provide a simple, easily manufactured internal combustion engine combustion chamber system having increased operating efficiency. Another object is to provide such as system that provides both increased fuel efficiency and higher performance. A further object is to provide such a system with high thermal efficiency. Yet another object is to provide a system capable of operating at high compression ratios with a variety of different fuels. Still another object is to provide a fast burn chamber with improved combustion efficiency and reduced hydrocarbon, carbon monoxide and nitrous oxide emissions.
SUMMARY OF THE INVENTION
The above-noted objects, and others, are accomplished, basically, by a three valve combustion chamber system for use with internal combustion engine containing a piston and a cylinder head forming a combustion chamber therebetween. The system comprises three valves in the cylinder head, spaced around the cylinder axis, two of the valves adapted to act as intake valves and the third as an exhaust valve. For most effective operation, the valves are generally round and have a ratio of total exhaust valve cross sectional area to total intake valve cross sectional area in the range of 45% to 65%.
The system of this invention may use any suitable ignition means. Typically with a gasoline or natural gas powered vehicle spark plugs may be used. In a diesel engine, a glow plug or injection type igniter are typically used. One or more ignition means may be provide at each cylinder, at any suitable locations.
In a first version, three peripheral ignition means are substantially centrally located in the areas surrounded by adjacent valves and the edge of the combustion chamber. A central, fourth, ignition means may be located substantially on the cylinder axis, surrounded by the three valves. A second version has a single central ignition means located substantially on the cylinder axis, surrounded by the three valves. Other suitable positions of one or more ignition means may be used.
The cylinder head surface forming one side of the combustion chamber may have hemispheric depressions containing each of the valves, with the piston having approximately areas corresponding to matching areas on the cylinder head located around the edge of the combustion chamber and extending inwardly somewhat between adjacent valves. These opposed matching areas are configured so that as the piston and head areas closely approach each other during engine operation a very efficient “squish” area is created. Since there are three separate spaced squish areas or pads, the fuel/air mixture is driven along each spaced squish area toward the center of the combustion chamber as the piston approaches top dead center to provide a highly turbulent colliding mixture. This arrangement substantially improves combustion and fuel efficiency.
For best results, three squish pads are used, with the squish pads around the piston periphery, one squish pad lying between each pair of adjacent valves. The total squish area should cover at least about 12% of the bore area. Smaller squish areas are disadvantageous because they provide insufficient charge turbulence and a slow fuel burn and reaction time, resulting in inefficient combustion. The maximum squish area is limited only by the need to provide room for the valves and ignition means.
In order to obtain this squish effect, the matching areas may be flat, may be radiused or angled. The piston surface making up one wall of the combustion chamber may be curved or flat, or any combination thereof. The piston face may typically be entirely flat or may have a shallow central recess (typically having a depth of from about 0.1 to 1 in.) corresponding generally to the pattern of valves in the head. For example, the piston face may have a generally planar domed central area and an angled edge portion extending from the dome to the piston face edge, matching a similarly configured opposite area on the head. Alternatively, the edge portion may be radiused between a domed central flat area and the piston edge, with the edge portion of the head corresponding thereto.
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Benton Jason
Kamen Noah P.
Kelly Bauersfeld Lowry & Kelley LLP
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