Internal-combustion engines – Valve – Valve seat relation
Reexamination Certificate
1999-11-17
2001-07-17
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Valve
Valve seat relation
Reexamination Certificate
active
06260530
ABSTRACT:
BACKGROUND OF THE INVENTION
A significant factor in the efficiency of an internal combustion engine is the degree to which fuel droplets are atomized and vaporized. Ideally, the combustion chamber should contain an air-fuel mixture that is in a completely gaseous state before ignition.
Imparting a vortex to the air-fuel mixture as it enters the combustion chamber improves combustion efficiency. Liquid fuel particles that are swirling in a vortex disburse more readily and evenly than particles that are simply drawn into the combustion chamber without a vortex.
The benefits of imparting a vortex to an air-fuel mixture on its way to a combustion chamber are known. Conventional structure for imparting such a vortex includes valve having helical grooves, valves and valve seat insert having vaned surfaces, and rifled intake ports and manifolds. An example of a valve having helical grooves is disclosed in U.S. Pat. No. 5,771,852 to Heimann, Jr., et al. Examples of conventional valves and valve seat inserts that use vaned surfaces to impart a vortex are found in U.S. Pat. No. 4,744,340 to Kirby for a “vortex generator intake valve,” and U.S. Pat. No. 4,389,988 to Ong for a “swirl generating device,” which is installed at the opening of a combustion chamber's intake port. U.S. Pat. No. 5,632,145 to Hunt discloses an example of a rifled intake manifold.
Grooves on a valve can impart a vortex to an air-fuel mixture, but a grooved valve presents certain disadvantages. First, a valve is a structural member, and its strength is compromised by removing structural material from its surface to create grooves. Second, only the neck of the valve has enough surface area in contact with the incoming air-fuel mixture to interact significantly with the mixture, and the neck of the valve slows down the air-fuel mixture by the time the mixture approaches it. Consequently, grooves on the neck of the valve cannot interact with the air-fuel mixture as efficiently as grooves in other parts of an engine.
Vaned surfaces present at least two significant problems when placed in the path of an air-fuel mixture in an internal combustion engine. First, vanes used to impart a vortex to the mixture also reduce its intake velocity, which is undesired. Reducing intake velocity of the air-fuel mixture reduces the maximum horsepower of the engine. Second, vanes such as those disclosed in the '988 patent have the potential to break off during operation of the engine. Vane fragments can cause seizure of a piston and destruction of the engine.
Rifling the walls of an intake port or manifold avoids the problems of vaned surfaces. To modify an existing engine to a vortex-inducing configuration, however, a significant portion of the engine must be replaced. For example, an existing engine manifold may be replaced with a rifled manifold such as that disclosed in the '145 patent.
Accordingly, the need remains for an engine component that can be retrofitted into an existing engine in a region where an air-fuel mixture enters the engine's combustion chamber at relatively high velocity. The need further remains for such a component that can be installed as an alternative or in addition to a grooved valve, without the need for replacement of a significant portion of the engine.
SUMMARY OF THE INVENTION
A valve seat insert according to various aspects of the present invention includes a ring that is bounded by surfaces including an inner wall. The inner wall is circumferentially disposed about an imaginary central axis, which passes through the insert. The inner wall includes a plurality of grooves. Each groove is oriented diagonally with respect to the central axis.
In an operating engine, the valve seat insert cooperates with a valve, which regulates the flow of an air-fuel mixture into the engine's combustion chamber. The air-fuel mixture comes into contact with the grooves of the insert before coming into contact with the valve. Advantageously, the grooves interact with the air-fuel mixture in a region of high velocity, before it is slowed by the valve. employing grooves rather than vanes to impart a vortex, a valve seat insert according to various aspects of the invention improves combustion efficiency while keeping its inner wall (the inlet to the combustion chamber) free of obstructions. Consequently, the insert promotes disbursement of liquid fuel particles without restricting flow of the particles into the combustion chamber. In addition, by omitting vanes, the insert avoids the possibility of vanes breaking off during operation of the engine and causing damage.
A valve seat insert according to one aspect of the invention is fabricated from an alloy including chrome, carbon, and iron. Such an insert is able to tolerate the high level of heat generated during operation of the engine and to conduct heat into surrounding structure of the engine. According to further aspects of the invention, the insert can be fabricated from particularly advantageous alloys. These alloys variously have beneficial properties including heat tolerance and thermal conductivity. One of those alloys achieves these beneficial properties at reduced cost by including tungsten.
According to further aspects of the invention, the grooves of the valve seat insert can have particularly advantageous shapes and arrangements along the inner wall of the insert. For example, the grooves can be oriented at an angle about 70-80 degrees from a plane parallel to the central axis of the insert. In addition, the grooves can have a variable depth, the greatest depth being at the midpoint of the grooves. The grooves can also taper to the inside wall of the insert, rather than beginning and ending abruptly.
An engine can be modified to employ grooved valve seat inserts, according to various aspects of the present invention, to provide improved combustion efficiency without the need for replacement of significant parts of the engine. Replacement of a conventional valve seat insert is less expensive than replacement of an entire intake manifold. Modification can include replacement of conventional valve seat inserts with grooved inserts as an alternative to the replacement of plain valves with grooved valves. Such modification improves engine efficiency without the need for grooved valves, which may have reduced structural integrity. Alternatively, an engine can be modified to use, in combination, grooved valve seat inserts of the invention and conventional grooved valves.
REFERENCES:
patent: 1512952 (1924-10-01), Secor
patent: 1555991 (1925-10-01), Konar
patent: 3653368 (1972-04-01), Scherenberg
patent: 4151816 (1979-05-01), Schroder
patent: 4355604 (1982-10-01), Chaibongsai
patent: 4424777 (1984-01-01), Klomp
patent: 4756281 (1988-07-01), Chen et al.
Hoffman Louis J.
Huynh Hai
Kamen Noah P.
Suominen Edwin A.
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