US5522356A
Expired / Lapsed
US
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Method and apparatus for transferring heat energy from engine housing to expansion fluid employed in continuous combustion, pinned vane type, integrated rotary compressor-expander engine system
Assignee: Spread Spectrum Inc
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Filing: 1994-09-29
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Granted: 1996-06-04
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Expires: 2014-09-29
Abstract
Abstract A continuous combustion, pinned vane type, positive displacement, rotary compressor and expander engine system comprises a compressor which outputs compressed air, a combustor which effects continuous combustion of a combustion gas mixture containing fuel and the compressed air and produces a combustion gas output. An expander is coupled to receive a mixture of combustion gas and an expansion fluid as an expandable working gas. The expander expands the expandable working gas and performs work to cause rotation of an engine output shaft. Each the compressor and the expander comprises a respective pinned vane type, positive displacement, rotary device. The engine system further includes an expansion fluid flow path having an input port to which the expansion fluid is supplied, and an output port coupled to combine the expansion fluid with the combustion gas as the expandable working gas. The expansion fluid flow path is in thermal communication with the expander housing such that there is a thermal energy transfer from the housing to the expansion fluid, thereby increasing the thermal energy of the expansion fluid to the extent where a phase transformation takes place from the liquid phase to the gaseous phase. In the gaseous phase the expansion fluid is combined with the combustion gas to form the expandable working gas.
Inventors
- 👤 William R. Palmer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 10:26
CPC Classifications
F; F01; F01C; F01C1/00; F01C1/30; F01C1/34; F01C1/344; F01C1/352; F01C11/00; F01C11/002; F01C11/004; F02; F02B; F02B53/00; F02B2053/005; F02G; F02G2250/00; F02G2250/03
Claims Analysis
Total Claims: 66
Claim 1
Independent Claim
313 words
A rotary expansion device comprising: a housing having an interior gas expansion chamber surrounding a first axis and an inlet port into which an expandable working gas is introduced; an outer hub assembly, disposed inside said gas expansion chamber and surrounding a second axis, said second axis being offset from said first axis; an inner hub, disposed inside said outer hub assembly, and surrounding said first axis; a plurality of blades, each of which extends radially from said inner hub and passes through said outer hub assembly to an interior surface of said gas expansion chamber, thereby forming a plurality of relatively airtight compartments between said interior surface of said gas expansion chamber, said outer hub assembly, and respective pairs of blades, with the volume of said compartments varying as a function of rotative position about said first axis; a linkage arrangement, which interconnects said inner hub with said outer hub exclusive of said blades, and is operative, in response to rotation of said outer hub assembly about said second axis by the expansion of said expandable working gas that has been introduced into said compartments from said inlet port, to drive said inner hub by said linkage arrangement therebetween; and a thermal transfer medium flow path having an input port to which a thermal transfer medium is supplied, and an output port coupled to combine said thermal transfer medium with a working gas introduced into said inlet port, said thermal transfer medium flow path being in thermal communication with said housing such that there is a thermal energy transfer from said housing to the thermal transfer medium within said thermal transfer medium flow path, thereby increasing the thermal energy of said thermal transfer medium that has been supplied to said input port of said thermal transfer medium flow path, and is output from said output port for combination with said working gas.
Claim 2
Dependent Claim
313 words
A rotary expansion device comprising: a housing having an interior gas expansion chamber surrounding a first axis and an inlet port into which an expandable working gas is introduced; an outer hub assembly, disposed inside said gas expansion chamber and surrounding a second axis, said second axis being offset from said first axis; an inner hub, disposed inside said outer hub assembly, and surrounding said first axis; a plurality of blades, each of which extends radially from said inner hub and passes through said outer hub assembly to an interior surface of said gas expansion chamber, thereby forming a plurality of relatively airtight compartments between said interior surface of said gas expansion chamber, said outer hub assembly, and respective pairs of blades, with the volume of said compartments varying as a function of rotative position about said first axis; a linkage arrangement, which interconnects said inner hub with said outer hub exclusive of said blades, and is operative, in response to rotation of said outer hub assembly about said second axis by the expansion of said expandable working gas that has been introduced into said compartments from said inlet port, to drive said inner hub by said linkage arrangement therebetween; and a thermal transfer medium flow path having an input port to which a thermal transfer medium is supplied, and an output port coupled to combine said thermal transfer medium with a working gas introduced into said inlet port, said thermal transfer medium flow path being in thermal communication with said housing such that there is a thermal energy transfer from said housing to the thermal transfer medium within said thermal transfer medium flow path, thereby increasing the thermal energy of said thermal transfer medium that has been supplied to said input port of said thermal transfer medium flow path, and is output from said output port for combination with said working gas.
Claim 3
Dependent Claim
16 words
A rotary expansion device according to claim 1, wherein said thermal transfer medium comprises a gas.
Claim 4
Dependent Claim
15 words
A rotary expansion device according to claim 1, wherein said thermal transfer medium comprises water.
Claim 5
Dependent Claim
15 words
A rotary expansion device according to claim 1, wherein said thermal transfer medium includes steam.
Claim 6
Dependent Claim
33 words
A rotary expansion device according to claim 1, further including a combustor, having an outlet port coupled to said inlet port of said housing and being operative to supply a combusted gas thereto.
Claim 7
Dependent Claim
82 words
A rotary expansion device according to claim 5, wherein said combustor includes an outer housing portion and a flame cage disposed therein, said flame cage having a plurality of openings through which compressed air is supplied and mixed with fuel supplied to said flame cage, thereby forming a combustion mixture, which is continuously combusted in said flame cage to produce said combusted gas, said combusted gas being supplied as part of said expandable working gas to an inlet throat of said housing.
Claim 8
Dependent Claim
47 words
A rotary expansion device according to claim 5, wherein said housing has an inlet throat coupled between said interior gas expansion chamber and said combustor outlet port, and wherein said thermal transfer medium flow path has an output port coupled to said inlet throat of said housing.
Claim 9
Dependent Claim
50 words
A rotary expansion device according to claim 5, wherein said housing has an inlet throat coupled between said interior gas expansion chamber and said combustor outlet port, and wherein said thermal transfer medium flow path has an output port coupled in fluid communication with an inlet throat of said housing.
Claim 10
Dependent Claim
39 words
A rotary expansion device according to claim 5, wherein said thermal transfer medium comprises an expansion fluid and wherein said thermal transfer medium flow path comprises an expansion fluid flow path that is in direct contact with said housing.
Claim 11
Dependent Claim
30 words
A rotary expansion device according to claim 9, wherein said housing has a wall which is integral with an expansion fluid passageway forming part of said expansion fluid flow path.
Claim 12
Dependent Claim
33 words
A rotary expansion device according to claim 10, wherein said expansion fluid passageway extends to the output port of said thermal transfer medium flow path adjacent to the outlet port of said combustor.
Claim 13
Dependent Claim
41 words
A rotary expansion device according to claim 11, wherein said expansion fluid passageway has at least one aperture in fluid communication with a combustion gas flow path through the outlet port of said combustor and said inlet port of said housing.
Claim 14
Dependent Claim
68 words
A rotary expansion device according to claim 10, wherein said expansion fluid flow path includes a section of meandering thermally conductive conduit extending through said expansion fluid passageway, said section of meandering thermally conductive conduit passing through a bore in said housing and providing an expansion fluid injection port in a combustion gas flow path from the output of said combustor to the inlet port of said housing.
Claim 15
Dependent Claim
50 words
A rotary expansion device according to claim 5, wherein said thermal transfer medium comprises an expansion fluid and wherein said thermal transfer medium flow path comprises a heat exchanger separate from said engine housing, wherein expansion fluid is heated and provided to an inlet throat of the expansion device housing.
Claim 16
Dependent Claim
41 words
A rotary expansion device according to claim 14, further including an exhaust manifold coupled to provide a working gas exhaust path for removing exhaust gas from said housing, and wherein an expansion fluid heat exchanger is coupled with said exhaust manifold.
Claim 17
Dependent Claim
124 words
A rotary expansion device according to claim 15, wherein said heat exchanger is coupled with a heating fluid return line ported to a first portion of said expansion fluid passageway, a second portion of which is ported to a heating fluid pump, which is coupled to pump heating fluid through said expansion fluid passageway to said heat exchanger, so that said heating fluid may be pumped in a closed system through the expansion fluid passageway and said heating fluid return line to said heat exchanger, and wherein said expansion fluid is supplied through said heat exchanger, so that its thermal energy is raised by heat transfer from both the expansion gas in the exhaust manifold and said heating fluid pumped through said heat exchanger.
Claim 18
Dependent Claim
20 words
A rotary expansion device according to claim 5, further comprising a compressor coupled to supply compressed air to said combustor.
Claim 19
Dependent Claim
85 words
A rotary expansion device according to claim 17, wherein said combustor includes an outer housing portion and a flame cage disposed therein, said flame cage having a plurality of openings through which compressed air from said compressor is supplied and mixed with fuel supplied to said flame cage, thereby forming a combustion mixture, which is continuously combusted in said flame cage to produce said combusted gas, said combusted gas being supplied as part of said expandable working gas to said inlet port of said housing.
Claim 20
Dependent Claim
64 words
A rotary expansion device according to claim 18, wherein said thermal transfer medium flow path is routed around a perimeter of said outer housing portion of said combustor and coupled through an aperture in said outer housing portion of said combustor, upstream of the flame cage, so that said expansion fluid medium mixes with compressed air prior to being supplied into said flame cage.
Claim 21
Dependent Claim
43 words
A rotary expansion device according to claim 14, wherein an expansion fluid flow path is provided through an exhaust gas manifold heat exchanger and around an expansion fluid passageway, and is injected into a combustible gas inlet throat of said expansion device housing.
Claim 22
Dependent Claim
66 words
A rotary expansion device according to claim 18, wherein said thermal transfer medium flow path is routed through a passageway around said flame cage to a thermal medium injection zone downstream of where combustion occurs in said flame cage, so that said thermal transfer medium may cool a high temperature section of said combustor, while absorbing additional potential energy prior to being mixed with combusted gas.
Claim 23
Dependent Claim
41 words
A rotary expansion device according to claim 5, wherein said combustor is operative to heat said thermal transfer medium which is mixed with said combusted gas before being provided as said expandable working gas to said inlet port of said housing.
Claim 24
Dependent Claim
15 words
A rotary expansion device according to claim 22, wherein said thermal transfer medium contains steam.
Claim 25
Dependent Claim
19 words
A rotary expansion device according to claim 1, wherein said expandable working fluid contains a combustion gas and steam.
Claim 26
Dependent Claim
47 words
A rotary expansion device according to claim 1, wherein said linkage arrangement comprises a set of gears which is arranged so as to cause said inner hub to rotate one revolution about said first axis for everyone rotation of said outer hub assembly about said second axis.
Claim 27
Dependent Claim
23 words
A rotary expansion device according to claim 1, wherein said thermal transfer medium is comprised of water and at least one additional substance.
Claim 28
Dependent Claim
33 words
A rotary expansion device according to claim 20, wherein said expansion fluid flow path comprises a steam supply line, which is routed through a compressed air supply passageway surrounding said combustor flame cage.
Claim 29
Dependent Claim
212 words
An engine system comprising a housing containing a compressor which is operative to output compressed air, a combustor which is operative to effect continuous combustion of a combustion gas mixture containing fuel and said compressed air and produce a combustion gas output, and an expander to which a mixture of said combustion gas and an expansion fluid is supplied as an expandable working gas, said expander being operative to expand said expandable working gas and perform work which causes rotation of an engine output shaft, each of said compressor and said expander comprising a respective pinned vane type, positive displacement, rotary device, and wherein said engine system further includes an expansion fluid flow path having an input port to which said expansion fluid is supplied, and an output port coupled to combine said expansion fluid with said combustion gas as said expandable working gas, said expansion fluid flow path being in thermal communication with said housing such that there is a thermal energy transfer from said housing to said expansion fluid, thereby increasing the thermal energy of said expansion fluid that has been supplied to said input port of said expansion fluid flow path, and is output from said output port for combination with said combustion gas as said expandable working gas.
Claim 30
Dependent Claim
212 words
An engine system comprising a housing containing a compressor which is operative to output compressed air, a combustor which is operative to effect continuous combustion of a combustion gas mixture containing fuel and said compressed air and produce a combustion gas output, and an expander to which a mixture of said combustion gas and an expansion fluid is supplied as an expandable working gas, said expander being operative to expand said expandable working gas and perform work which causes rotation of an engine output shaft, each of said compressor and said expander comprising a respective pinned vane type, positive displacement, rotary device, and wherein said engine system further includes an expansion fluid flow path having an input port to which said expansion fluid is supplied, and an output port coupled to combine said expansion fluid with said combustion gas as said expandable working gas, said expansion fluid flow path being in thermal communication with said housing such that there is a thermal energy transfer from said housing to said expansion fluid, thereby increasing the thermal energy of said expansion fluid that has been supplied to said input port of said expansion fluid flow path, and is output from said output port for combination with said combustion gas as said expandable working gas.
Claim 31
Dependent Claim
14 words
An engine system according to claim 28, wherein said expansion fluid comprises a gas.
Claim 32
Dependent Claim
15 words
An engine system according to claim 28, wherein said expansion fluid contains water or steam.
Claim 33
Dependent Claim
50 words
An engine system according to claim 28, wherein said expansion fluid flow path passes through said combustor so as to cause additional heat energy to be added to said expansion fluid as it passes through said combustor, thereby cooling said combustor and increasing the potential energy of said expansion fluid.
Claim 34
Dependent Claim
96 words
An engine system according to claim 31, wherein said expansion fluid has a flow rate through said expansion fluid flow path which is controlled so that the temperature of said expandable working gas being supplied to said expander is controllably regulated under a constant fuel flow rate, whereby as the mass flow rate of said expansion fluid increases, the temperature of said expandable working gas being supplied to said expander decreases, and as the mass flow rate of said expansion fluid decreases, then the temperature of said expandable working gas being supplied to said expander increases.
Claim 35
Dependent Claim
21 words
An engine system according to claim 28, wherein said expansion fluid flow path is in direct contact with said engine housing.
Claim 36
Dependent Claim
29 words
An engine system according to claim 33, wherein said housing has a wall which is integral with an expansion fluid passageway forming part of said expansion fluid flow path.
Claim 37
Dependent Claim
41 words
An engine system according to claim 34, wherein said expansion fluid passageway passageway has at least one aperture in fluid communication with a combustion gas flow path through the outlet port of said combustor and said inlet port of said housing.
Claim 38
Dependent Claim
67 words
An engine system according to claim 34, wherein said expansion fluid flow path includes a section of meandering thermally conductive conduit extending through said expansion fluid passageway, said section of meandering thermally conductive conduit passing through a bore in said housing and providing an expansion fluid injection port in a combustion gas flow path from the output of said combustor to the inlet port of said housing.
Claim 39
Dependent Claim
22 words
An engine system according to claim 28, wherein said expansion fluid flow path contains a heat exchanger separate from said engine housing.
Claim 40
Dependent Claim
40 words
An engine system according to claim 37, wherein said expander includes an exhaust manifold coupled to provide a working gas exhaust path for removing exhaust gas from said housing, and wherein said heat exchanger is coupled with said exhaust manifold.
Claim 41
Dependent Claim
113 words
An engine system according to claim 38, wherein said heat exchanger is coupled with a heating fluid return line ported to a first portion of said expansion fluid passageway, a second portion of which is ported to a heating fluid pump, which is coupled to pump heating fluid through said expansion fluid passageway to said heat exchanger, so that heating fluid may be pumped in a closed system through the expansion fluid passageway and said heating fluid return line to said heat exchanger, and wherein said expansion fluid is supplied through said heat exchanger, so that its thermal energy is raised by heat transfer from said heating fluid pumped through said heat exchanger.
Claim 42
Dependent Claim
87 words
An engine system according to claim 28, wherein said combustor includes an outer housing portion and a flame cage disposed therein, said flame cage having a plurality of openings through which compressed air from said compressor is supplied and mixed with fuel supplied to said flame cage, thereby forming a combustion mixture, which is continuously combusted in said flame cage to produce said combusted gas, said combusted gas being supplied as part of said expandable working gas to said inlet port of the housing of said expander.
Claim 43
Dependent Claim
61 words
An engine system according to claim 40, wherein said expansion fluid flow path is routed around a perimeter of said outer housing portion of said combustor and coupled through an aperture in said outer housing portion of said combustor, upstream of the flame cage, so that said expansion fluid mixes with compressed air prior to being supplied into said flame cage.
Claim 44
Dependent Claim
63 words
An engine system according to claim 40, wherein said expansion fluid flow path is routed through a passageway around said flame cage to an expansion fluid injection zone downstream of where combustion occurs in said flame cage, so that said expansion fluid may cool a high temperature section of said combustor, while absorbing additional potential energy prior to being mixed with combusted gas.
Claim 45
Dependent Claim
32 words
An engine system according to claim 42, wherein said expansion fluid flow path comprises a steam supply line, which is routed through a compressed air supply passageway surrounding said combustor flame cage.
Claim 46
Dependent Claim
44 words
An engine system according to claim 42, wherein said expansion fluid flow path comprises a steam supply line, which is routed through said compressed air supply passageway surrounding said combustor flame cage and is ported through openings into an inlet throat of said housing.
Claim 47
Dependent Claim
71 words
An engine system according to claim 28, wherein said expansion fluid comprises a liquid having increased potential energy, which, upon changing phase to a gaseous phase is injected into the combustion gas flow path of said combustor as steam component of said expandable working gas, and is allowed to expand with constituents of a combusted gas mixture in said expander, thereby performing mechanical work, which causes rotation of said output shaft.
Claim 48
Dependent Claim
105 words
An engine system according to claim 28, wherein said expansion fluid comprises a liquid having increased potential energy, which, upon changing phase to a gaseous phase is injected into the combustion gas flow path of said combustor as steam component of said expandable working gas, and is allowed to expand with constituents of a combusted gas mixture in said expander, thereby performing mechanical work, which causes rotation of said output shaft, and wherein that portion of said expansion fluid which is still in a liquid phase is also injected into said combustion gas and transitions to a gas phase when mixing with said combustion gas.
Claim 49
Independent Claim
252 words
A method of controlling the operation of an engine system having a compressor which is operative to output compressed air, a combustor which is operative to effect continuous combustion of a combustion gas mixture containing fuel and said compressed air and produce a combustion gas output, and an expander to which a mixture of said combustion gas and an expansion fluid is supplied as an expandable working gas, said expander being operative to expand said expandable working gas and perform work which causes rotation of an engine output shaft, each of said compressor and said expander comprising a respective pinned vane type, positive displacement, rotary device, comprising the steps of: (a) coupling an expansion fluid flow path in thermal communication with a housing of said expander rotary device, so that thermal energy within the housing of said expander rotary device is coupled to said expansion fluid flow path, said expansion fluid flow path having an output port coupled in fluid communication with combustion gas of said combustor; and (b) controllably causing expansion fluid to flow through said expansion fluid flow path to be combined with said combustion gas as said expandable working gas, such that there is a thermal energy transfer from said housing to said expansion fluid, thereby causing said expansion fluid to absorb thermal energy from the expander housing, and increasing the thermal energy of said expansion fluid that has been supplied to said expansion fluid flow path, and is combined with combustion gas to form said expandable working gas.
Claim 50
Independent Claim
252 words
A method of controlling the operation of an engine system having a compressor which is operative to output compressed air, a combustor which is operative to effect continuous combustion of a combustion gas mixture containing fuel and said compressed air and produce a combustion gas output, and an expander to which a mixture of said combustion gas and an expansion fluid is supplied as an expandable working gas, said expander being operative to expand said expandable working gas and perform work which causes rotation of an engine output shaft, each of said compressor and said expander comprising a respective pinned vane type, positive displacement, rotary device, comprising the steps of: (a) coupling an expansion fluid flow path in thermal communication with a housing of said expander rotary device, so that thermal energy within the housing of said expander rotary device is coupled to said expansion fluid flow path, said expansion fluid flow path having an output port coupled in fluid communication with combustion gas of said combustor; and (b) controllably causing expansion fluid to flow through said expansion fluid flow path to be combined with said combustion gas as said expandable working gas, such that there is a thermal energy transfer from said housing to said expansion fluid, thereby causing said expansion fluid to absorb thermal energy from the expander housing, and increasing the thermal energy of said expansion fluid that has been supplied to said expansion fluid flow path, and is combined with combustion gas to form said expandable working gas.
Claim 51
Dependent Claim
113 words
A method according to claim 47, wherein said housing of said expander rotary device is configured to form a portion of said expansion fluid flow path, which extends to a coupling port to which a combustion gas output of said combustor is coupled, so that during step (b), said housing serves to raise the temperature of said expansion fluid that has been injected into said expansion fluid flow path, as said expansion fluid travels and is conductively heated by the elevated temperature of said expander housing, whereby said expander housing is cooled by thermal exchange with said expansion fluid, which operates to maintain the temperature of the housing at a relatively steady value.
Claim 52
Dependent Claim
13 words
A method according to claim 47, wherein said expansion fluid comprises a gas.
Claim 53
Dependent Claim
18 words
A method according to claim 47, wherein said expansion fluid comprises at least one of water and steam.
Claim 54
Dependent Claim
49 words
A method according to claim 47, wherein said expansion fluid flow path passes through said combustor so as to cause additional heat energy to be added to said expansion fluid as it passes through said combustor, thereby cooling said combustor and increasing the potential energy of said expansion fluid.
Claim 55
Dependent Claim
90 words
A method according to claim 51, wherein step (b) comprises controlling the flow rate of said expansion fluid through said expansion fluid flow path so that the temperature of said expandable working gas being supplied to said expander is controllably regulated, whereby as the mass flow rate of said expansion fluid increases, the temperature of said expandable working gas being supplied to said expander decreases, and as the mass flow rate of said expansion fluid decreases, then the temperature of said expandable working gas being supplied to said expander increases.
Claim 56
Dependent Claim
25 words
A method according to claim 47, wherein step (a) comprises providing said expansion fluid flow path in direct contact with said expander rotary device housing.
Claim 57
Dependent Claim
44 words
A method according to claim 53, wherein step (a) comprises porting said expansion fluid passageway at a location adjacent to a combustion gas output port of said combustor, so that said expansion fluid mixes with said combustion gas to form said expandable working gas.
Claim 58
Dependent Claim
22 words
A method according to claim 47, wherein step (a) comprises coupling said expansion fluid passageway through an expansion exhaust gas heat exchanger.
Claim 59
Dependent Claim
66 words
A method according to claim 54, wherein step (a) comprises extending a section of meandering thermally conductive conduit extending through said expansion fluid passageway, so that said section of meandering thermally conductive conduit passes through a bore in said housing and providing an expansion fluid injection port in a combustion gas flow path from the output of said combustor to the inlet port of said housing.
Claim 60
Dependent Claim
20 words
A method according to claim 56, wherein said expansion fluid flow path contains a heat exchanger separate from said housing.
Claim 61
Dependent Claim
86 words
A method according to claim 47, wherein said combustor includes an outer housing portion and a flame cage disposed therein, said flame cage having a plurality of openings through which compressed air from said compressor is supplied and mixed with fuel supplied to said flame cage, thereby forming a combustion mixture, which is continuously combusted in said flame cage to produce said combusted gas, said combusted gas being supplied as part of said expandable working gas to said inlet port of the housing of said expander.
Claim 62
Dependent Claim
62 words
A method according to claim 58, wherein step (a) comprises routing said expansion fluid flow path around a perimeter of said outer housing portion of said combustor and coupled through an aperture in said outer housing portion of said combustor, upstream of the flame cage, so that said expansion fluid mixes with compressed air prior to being supplied into said flame cage.
Claim 63
Dependent Claim
64 words
A method according to claim 58, wherein step (a) comprises routing said expansion fluid flow path through a passageway around said flame cage to an expansion fluid injection zone downstream of where combustion occurs in said flame cage, so that said expansion fluid may cool a high temperature section of said combustor, while absorbing additional potential energy prior to being mixed with combusted gas.
Claim 64
Dependent Claim
26 words
A method according to claim 60, wherein step (a) comprises routing a steam supply line through a compressed air supply passageway surrounding said combustor flame cage.
Claim 65
Dependent Claim
71 words
A method according to claim 47, wherein said expansion fluid comprises a liquid having increased potential energy, which is injected into said combustion gas output at a combustor outlet prior to being liberated into a gaseous phase as a component of said expandable working gas, so that said gaseous phase expansion fluid is allowed to expand in said expander, thereby performing mechanical work, which causes rotation of said engine output shaft.
Claim 66
Dependent Claim
73 words
A method according to claim 47, wherein a portion of said expansion fluid comprises a liquid having increased potential energy, which is injected into said combustion gas output at a combustor outlet prior to being liberated into a gaseous phase as a component of said expandable working gas, so that said gaseous phase expansion fluid is allowed to expand in said expander, thereby performing mechanical work, which causes rotation of said output shaft.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-06-04 | 1999-12-04 | 2000-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-06-04 | 2003-12-04 | 2004-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-06-04 | 2007-12-04 | 2008-06-04 | $7700.00 | Window Closed / Lapsed |