Internal-combustion engines – Charge forming device – Heating of combustible mixture
Reexamination Certificate
1999-12-14
2001-07-03
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Charge forming device
Heating of combustible mixture
C060S712000
Reexamination Certificate
active
06253745
ABSTRACT:
BACKGROUND OF THE INVENTION
Six-stroke cycle engines have been proposed wherein the first four strokes function as a conventional internal combustion engine operating on a fuel charge and the fifth and sixth strokes operate on a steam charge. The fuel charge strokes include a standard intake stroke, a compression stroke, a power stroke, and an exhaust stroke. The products of combustion are exhausted from the combustion chamber, and water is injected therein to be converted by remaining heat into steam. The steam charge generates a steam expansion power stroke, and the steam is excised during a steam exhaust stroke.
Past attempts at such an arrangement have met with limited success, generally resulting in configurations of complicated construction and/or low efficiency. Examples include the engine described in U.S. Pat. No. 1,339,176, where the heat of the exhausted products of combustion were entirely lost, resulting in highly inefficient operation. Six-stroke cycle engines of the type shown in U.S. Pat. Nos. 1,217,788 and 2,671,311 relied on steam generating means external of the engine itself for providing the steam for a steam expansion stroke. Such arrangements were complicated and expensive to produce, and introduced additional components through which heat can be lost.
An engine described in U.S. Pat. No. 4,143,518 utilizes the reciprocating mechanism of the internal combustion engine for the steam power stroke and recovers a portion of the heat of the exhausted products of combustion. Such a configuration recovers only a small fraction of this exhausted heat. This is due to inadequate expansion during the steam power stroke and limitations on the maximum steam temperature that could be obtained by conducting the heat from the exhaust products through the cylinder walls. The heat of the exhausted products of combustion is recovered by passing the exhausted products over fins attached to the outside of the cylinder. The heat transferred to the fins is utilized to heat the cylinder wall. A primary limitation in this technique is that the cylinder wall can only be heated to approximately 400 degrees F. without destroying the oil film required to lubricate the piston. This significantly limits the maximum temperature of the steam formed when water is injected into the cylinder. In addition, no provision is made to adequately expand the steam. The expansion ratio of the fuel power stroke is limited to approximately 10:1 due to the characteristics of the gasoline used for a conventional internal combustion engine. This is insufficient for complete recovery of the mechanical work potentially recoverable from the steam during the steam expansion stroke.
The engine described by Hallstrom, U.S. Pat. No. 4,433,548, also utilized the reciprocating mechanism of the internal combustion engine for the steam power stroke. This design only recovers a small fraction of the exhausted heat due to limited expansion of the steam during the steam power stroke. The volume in which the steam is generated includes both the steam generation chamber and the clearance volume between the top of the piston and the cylinder head. No provision is made to minimize the clearance volume at the initiation of the steam power stroke. Therefore the steam expansion ratio is considerably less than the combustion cycle expansion ratio. This significantly limits the efficiency of the steam cycle.
SUMMARY OF THE INVENTION
The present invention is directed to a multiple cycle engine, for example a six-stroke cycle engine, wherein the first four strokes function as a conventional internal combustion engine and include an fuel intake stroke, a fuel compression stroke, a fuel power stroke and an fuel exhaust stroke; and further including additional strokes, namely, a vapor power stroke and a vapor exhaust stroke for generating additional power from heat extracted from the fuel exhaust, in a manner which overcomes the limitations of conventional approaches.
During the fuel exhaust stroke, the products of combustion are directed through a heat regenerator located in a vapor heating chamber adjacent the combustion chamber. Upon completion of the exhaust stroke, fluid is injected directly into the heat regenerator and heated. The vapor is admitted into the combustion chamber to provide a vapor power stroke, which is followed by a vapor exhaust stroke.
In this manner, the present invention provides an engine which efficiently recovers a significant portion of the heat normally rejected by an internal combustion engine and converts this otherwise wasted heat into useful work.
The present invention further eliminates the conventional cooling system for an internal combustion engine while also providing improved cooling for the exhaust valve and other regions of the combustion chamber subject to severe thermal stress.
In one embodiment, the present invention is directed to an internal combustion engine. The engine includes a fuel combustion chamber having an exhaust port at which heated fuel exhaust generated by combustion is released from the chamber. A heat regenerator preferably comprises a heat conductive element configured to promote turbulent flow of the fuel exhaust therethrough. The heat regenerator is in communication with the exhaust port for extraction of heat from the fuel exhaust. A fluid source releases fluid into the heat regenerator where the fluid absorbs heat and is converted to vapor. A valve releases the vapor into the chamber for powering the engine.
In a preferred embodiment, the fluid comprises water and the vapor comprises steam. The released vapor generates a vapor charge in the chamber for powering the engine. The vapor charge follows a fuel charge which likewise powers the engine and produces the fuel exhaust.
In a second embodiment, the fluid source releases a cool, high-pressure vapor into the heat regenerator where the vapor is heated. A valve releases the vapor charge into the chamber for powering the engine. The vapor charge follows a fuel charge which likewise powers the engine and produces the fuel exhaust.
In a third embodiment, the liquid comprises a mixture of water and a hydrocarbon fuel such as methanol or gasoline.
The present invention is further directed to a heat regenerator including a heat conductive element configured to promote turbulent flow of a fluid therethrough. The heat regenerator is adapted to be alternately heated by combustion gas and cooled by vapor heating.
The heat conductive element preferably comprises a plurality of wire mesh elements stacked at the various rotation angles. The wire mesh elements may comprise stainless steel or ceramic. In alternative embodiments, the heat conductive element may comprise sintered metal, open-cell ceramic foam, a metal foil, or a patterned foil wound into an annular shape.
The heat regenerator is preferably coupled proximal to the fuel combustion chamber so as to minimize heat loss during the transfer of combustion gas from the fuel combustion chamber to the heat regenerator and during the transfer of vapor from the heat regenerator to the fuel combustion chamber.
In a preferred embodiment, an exhaust valve controls the release of fuel exhaust from the heat regenerator. The exhaust valve may include a shaft which coaxial with and slidable relative to a shaft of the heat transfer valve. The heat regenerator may be positioned between the exhaust valve and the heat transfer valve. The valves may comprise, for example, poppet valves.
The heat regenerator is preferably enclosed in a vapor heating chamber in communication with the exhaust valve, the fuel source, and the heat transfer valve. The volume of the fuel combustion chamber is preferably controllable such that a first volume of the chamber at the initiation of combustion is different than a second volume of the chamber at the initiation of the release of the vapor. The first and second volumes are preferably controlled by the top dead center position of a piston coupled to an eccentric. Alternatively, the volumes may be controlled by a piston coupled to a multi-link eccentric mec
McMahon Marguerite
Mills & Onello LLP
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