The present invention relates in general to the field of Stirling engines, and more particularly to the design and fabrication of a novel Stirling engine with augmented heat transfer due to the profile and segmented design of the rotary displacer.
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Without limiting the scope of the invention, its background is described in connection with the different displacer piston designs for Stirling engines and related devices.
U.S. Pat. No. 4,458,489 issued to Walsh (the '489 patent) describes a new and improved resonant free-piston Stirling engine and method of operation employing a novel virtual rod displacer. According to the '489 patent a rod is secured to and reciprocally moves with the displacer within the Stirling engine and has a rod piston area formed on the end of the rod remote from the displacer with the rod piston area also being subjected to the working gas periodic pressure wave. Suitable support bearings are designed within the Stirling engine housing for reciprocatingly supporting the displacer and rod assembly within the Stirling engine with a set of opposed acting gas springs being provided to act on the displacer end and rod assembly area end of the displacer and rod assembly. One end of the displacer is designed to have a greater effective area acted upon by the gas contained within the engine than the effective area of the opposite end whereby the unbalanced areas of the opposing displacer ends create a differential force when acted upon by a periodic pressure wave, causing reciprocating motion of the displacer and virtual rod assembly. In the preferred embodiment a displacer electrodynamic machine is provided for selectively driving or loading the displacer and rod assembly to thereby control the stroke and/or phase angle at which the displacer and rod assembly move relative to the output power piston or work member.
United States Patent Application No. 20070193266 (McConaghy, 2007) describes a Stirling engine machine comprises a plurality of opposing pairs of cylinder modules. Each cylinder module comprises a first end, a second end, and a piston moveable along a longitudinal axis extending between the first and second ends. The opposing pairs of cylinder modules have axes that are substantially aligned with each other such that movement of the pistons of opposing pairs substantially dynamically cancel. The opposing pairs of cylinder modules have first ends that are in proximity to each other.
United States Patent Application No. 20040194461 (Yamamato, 2003) discloses a Stirling engine comprising: a displacer unit having displacer cylinders, displacers slidably arranged in the chambers of the displacer cylinders, expansion chambers and contraction chambers into which, and from which, the operation gas flows with the operation of the displacers; and a power piston unit having a power cylinder having an operation chamber communicated with either the expansion chamber or the contraction chamber of the displacer unit, and a power piston slidably arranged in the power cylinder; wherein the displacer cylinders of the displacer unit are equipped with a heating wall surrounding a heat source and cooling walls forming a plurality of cylinder chambers surrounding the heating wall; and the displacers of the displacer unit are slidably arranged in the plurality of cylinder chambers in the directions to approach the heat source and to separate away from the heat source.
The present invention provides a Stirling engine employing a segmented, rotary displacer for producing mechanical energy from a heat source. The engine includes an engine housing having a hot displacer side and a cold displacer side separated by an insulating seal, and an interior toroidal cavity to receive a gas; a rotor shaft rotatably positioned in the interior toroidal cavity; a segmented displacer mounted to the rotor shaft within the interior toroidal cavity, wherein the segmented displacer has 3 or more displacement segments wherein each of the 3 or more displacement segments individually comprise a chamber portion; one or more hot ports located on the hot displacer side, wherein the rotation of the segmented displacer moves the chamber portion to direct a hot gas to the one or more hot ports; one or more cold ports located on the cold displacer side, wherein the rotation of the segmented displacer moves the chamber portion to direct a cold gas to the one or more cold ports; and a hot side of a power piston cylinder connected to the one or more hot ports by a hot cross-over tube, wherein a power piston in the power piston cylinder moves outwards by the hot gas expanding.
The present invention also includes a multi-cylinder Stirling rotary engine having an engine housing with 2 or more cylinders, wherein each of the 2 or more cylinders comprise a hot displacer side and a cold displacer side separated by an insulating seal, and an interior toroidal cavity to receive a gas; a rotor shaft rotatably positioned in the interior toroidal cavity; a segmented displacer mounted to the rotor shaft within the interior toroidal cavity, wherein the segmented displacer has 3 or more displacement segments individually have a chamber portion; one or more hot ports located on the hot displacer side, wherein the rotation of the segmented displacer moves the chamber portion to direct a hot gas to the one or more hot ports; one or more cold ports located on the cold displacer side, wherein the rotation of the segmented displacer moves the chamber portion to direct a cold gas to the one or more cold ports; and a hot side of a power piston cylinder connected to the one or more hot ports by a hot cross-over tube, wherein a power piston in the power piston cylinder moves outwards by the hot gas expanding; and a belt to connect the segmented rotary displacer shafts of the 2 or more cylinders.
The present invention includes a method of making a multi-cylinder Stirling rotary engine by providing an engine housing having 2 or more cylinders wherein each of the 2 or more cylinders comprise a hot displacer side and a cold displacer side separated by an insulating seal, one or more hot ports located on the hot displacer side, one or more cold ports located on the cold displacer side and an interior toroidal cavity to receive a gas; positioning rotatably a rotor shaft in the interior toroidal cavity; connecting a segmented displacer comprising to the rotor shaft, wherein the segmented displacer comprises 3 or more displacement segments individually having a chamber portion that fills a portion of the toroidal cavity to direct the movement of a gas, wherein the rotation of the segmented displacer moves the chamber portion to direct a hot gas to the one or more hot ports and to direct a cold gas to the one or more cold ports; connecting a power piston cylinder housing a power piston to the one or more hot ports by a hot cross-over tube, wherein the power piston in the power piston cylinder moves outwards by the hot gas expanding; and a belt to connect the rotor shaft of the 2 or more cylinders.
For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures and in which:
While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention.
To facilitate the understanding of this invention, a number of terms are defined below. Terms defined herein have meanings as commonly understood by a person of ordinary skill in the areas relevant to the present invention. Terms such as “a”, “an” and “the” are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the invention, but their usage does not delimit the invention, except as outlined in the claims.
As used herein the term rotor, segment or displacer segment may be used interchangeably and refer to the same component as seen in
The present invention describes the design and fabrication of a Stirling engine with a unique profile and segmented design of the rotary displacer and the corresponding hot and cold halves of the surrounding displacer chamber. The displacer profile and segmented design augments heat transfer. The segmented displacer and displacer housing feature two novel rotary valves which direct the flow of the working gas to and from the power piston. The engine design of the present invention makes it flexible with regard to configuring multi-cylinder applications. This added flexibility of the present invention makes it unique or novel.
The engine described in the present invention is intended to power an electric generator for the purpose of recharging batteries. Such an engine-generator unit could be located on-board an electric powered vehicle or at a stationary installation where it could function as an individual vehicle or fleet recharger. Stationary applications extend beyond vehicular needs. In some embodiments, the present invention is used in conjunction with a generator while other embodiments are used alone.
The “existing technology” is represented mainly by conventional internal combustion engines. Stirling engines, in general, have the following advantages over internal combustion engines: they are more efficient; they are more reliable; they utilize a range of energy sources, many of which are renewable and/or less polluting (traditional combustion of a variety of fuels, biomass, concentrated solar energy, nuclear, geothermal, industrial process waste heat, etc.); they are quiet with respect to audible noise and radio interference. These advantages of Stirling engines are commonly cited in the literature.
The engine of the present invention is designed so that multiple units can be teamed together using a single timing belt (comparable to the serpentine belt which drives various accessories under the hood of an automobile). As such, it would be both easy and cost efficient to customize the number of “cylinders” available for a given application. This represents an advantage over the popular but more complex Gamma Stirlings. Commercial Gamma engines are multi cylinder, but the cylinders are machined or cast in-block, in a manner conceptually similar to an automobile engine. This increases their cost and weight and it also decreases their flexibility in terms of the number of cylinders available for varying applications, i.e., addition or subtraction of cylinders requires new castings. The engine of the present invention is superior to Alpha and Beta Stirling designs also, with regard to the minimum number of required moving parts per power cylinder.
Robert Stirling invented and patented the first Stirling engine in 1816. Additional patents were awarded for improvements during the ensuing years. The early applications of this invention were primarily industrial in nature, e.g., pumping water, driving machinery, etc. Developmental effort, at this time, was fueled by the high incidence of steam boiler explosions and their attendant loss of life. Eventually, refinements in steel manufacture and legislation alleviated the fear of such explosions and steam assumed the role of prime mover throughout the Industrial Revolution in the United States. Consequently, interest in the Stirling engine waned and development stagnated until the early 1940s. The desirability of a reliable, low cost engine generator for rural areas devoid of power grids became the motivational force for the Phillips Company to invest in Stirling research and development. From this time to the present day there has been continuous, although varying, levels of interest in the Stirling cycle. Findings have been promising. The science of thermodynamics enhanced understanding of the cycle; new materials increased reliability and power output. Engine configurations i.e., Alpha, Beta and Gamma, were established to mechanically classify Stirling engines. Pressurization and regeneration became characteristic of successful commercial applications. Today, Stirling engines and/or engine-generator sets can be found in agricultural communities, deep sea submersibles, hybrid automobiles, etc. The technology is under consideration for powering deep space exploration.
Three novel aspects of the engine of the present invention include (i) the segmented displacer with a stepped or radial profile, also apparent in the design of the displacer housing; (ii) the rotary valve mechanism; and (iii) a modular, multi-cylinder capability.
The first displacer segment, in conjunction with the hot and cold sides of the displacer housing, collectively act as two rotary valves which direct hot (expanding) working gas exclusively to the hot port. Likewise, these components direct the cold (contracting) working gas exclusively to the cold port. From the hot port, the working gas is directed, via the hot cross over tube, to the hot side of the power piston cylinder. The power piston moves outwards under the influence of the hot expanding gas. The rotary valve inhibits the hot expanding gas from backing up through the cold workspace of the displacer housing while on its route to the power piston (were it not to do so, energy would be lost from the hot gas to the liquid cooled passages of the cold workspace). As the power piston approaches its rearmost movement, both rotary valves momentarily overlap in the open condition. This is shortly followed by the hot valve closing completely (and remaining so for about 180 degrees of rotation) and the cold valve opening fully (and likewise remaining open for about 180 degrees of rotation). The power piston then moves forward forcing the working gas through the cold port and into the cold workspace of the displacer housing.
The initial position is “0” (
Table 2 illustrates a base set of specification to provide a point of reference and the skilled artisan will recognize that the individual values may be modified for the optimization of specific embodiments. For example, the bore and stroke maybe changes to provide a larger cylinder, the cycle volume and volume compression ratio may be adjusted to
The segmented displacer may be of a variety of sizes and proportional so can the housing to accommodate the segmented displacer. For example, the segmented displacer may a major outside diameter that ranges from 0.25 to 5″ (e.g., 2.450″); however, in certain applications the major outside diameter may be larger than 5″. Similarly, the length may range from 0.25 to 8″ (e.g., 3.866″); however, in certain applications the major outside diameter may be larger than 8″.
The present invention uses a Polyetheretherketone (PEEK) polymer composition. Other theremoplastic polymer compositions may also be used including Polycarbonate (PC), Polyhydroxyalkanoates (PHAs), Polyketone (PK), Polyester, Polyetheretherketone (PEEK), Polyetherketoneketone (PEKK), Polyetherimide (PEI), Polyethersulfone (PES), Polysulfone, Polyethylenechlorinates (PEC), and Polyimide (PI) are merely examples of polymers that may be used.
It is contemplated that any embodiment discussed in this specification can be implemented with respect to any method, kit, reagent, or composition of the invention, and vice versa. Furthermore, compositions of the invention can be used to achieve methods of the invention.
It will be understood that particular embodiments described herein are shown by way of illustration and not as limitations of the invention. The principal features of this invention can be employed in various embodiments without departing from the scope of the invention. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this invention and are covered by the claims.
All publications and patent applications mentioned in the specification are indicative of the level of skill of those skilled in the art to which this invention pertains. All publications and patent applications are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.
The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” The use of the term “or” in the claims is used to mean “and/or” unless explicitly indicated to refer to alternatives only or the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and/or.” Throughout this application, the term “about” is used to indicate that a value includes the inherent variation of error for the device, the method being employed to determine the value, or the variation that exists among the study subjects.
As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.
The term “or combinations thereof” as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “A, B, C, or combinations thereof” is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, MB, BBC, AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context.
All of the compositions and/or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.
This application claims priority to U.S. Provisional Application Ser. No. 61/243,011, filed Sep. 16, 2009, the contents of which is incorporated by reference herein in its entirety.
Number | Name | Date | Kind |
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3958422 | Kelly | May 1976 | A |
4372115 | Rauch | Feb 1983 | A |
4458489 | Walsh | Jul 1984 | A |
5907201 | Hiterer et al. | May 1999 | A |
8212445 | Ritchey | Jul 2012 | B2 |
20030000210 | Gross et al. | Jan 2003 | A1 |
20040194461 | Yamamoto | Oct 2004 | A1 |
20050060996 | Pellizzari et al. | Mar 2005 | A1 |
20060185825 | Chen et al. | Aug 2006 | A1 |
20070193266 | McConaghy | Aug 2007 | A1 |
20080148754 | Snytsar | Jun 2008 | A1 |
20080282695 | Sollie et al. | Nov 2008 | A1 |
20100064681 | Yegge | Mar 2010 | A1 |
20100162697 | Fleck | Jul 2010 | A1 |
Number | Date | Country | |
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20110061378 A1 | Mar 2011 | US |
Number | Date | Country | |
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61243011 | Sep 2009 | US |