SE541814C2 - Stirling engine comprising a transition flow element - Google Patents
Stirling engine comprising a transition flow elementInfo
- Publication number
- SE541814C2 SE541814C2 SE1850002A SE1850002A SE541814C2 SE 541814 C2 SE541814 C2 SE 541814C2 SE 1850002 A SE1850002 A SE 1850002A SE 1850002 A SE1850002 A SE 1850002A SE 541814 C2 SE541814 C2 SE 541814C2
- Authority
- SE
- Sweden
- Prior art keywords
- working
- cylinder
- channel
- displacer
- stirling engine
- Prior art date
Links
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
- F02G1/00—Hot gas positive-displacement engine plants
- F02G1/04—Hot gas positive-displacement engine plants of closed-cycle type
- F02G1/043—Hot gas positive-displacement engine plants of closed-cycle type the engine being operated by expansion and contraction of a mass of working gas which is heated and cooled in one of a plurality of constantly communicating expansible chambers, e.g. Stirling cycle type engines
- F02G1/044—Hot gas positive-displacement engine plants of closed-cycle type the engine being operated by expansion and contraction of a mass of working gas which is heated and cooled in one of a plurality of constantly communicating expansible chambers, e.g. Stirling cycle type engines having at least two working members, e.g. pistons, delivering power output
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
- F02G1/00—Hot gas positive-displacement engine plants
- F02G1/04—Hot gas positive-displacement engine plants of closed-cycle type
- F02G1/043—Hot gas positive-displacement engine plants of closed-cycle type the engine being operated by expansion and contraction of a mass of working gas which is heated and cooled in one of a plurality of constantly communicating expansible chambers, e.g. Stirling cycle type engines
- F02G1/045—Controlling
- F02G1/05—Controlling by varying the rate of flow or quantity of the working gas
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
- F02G2243/00—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes
- F02G2243/30—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having their pistons and displacers each in separate cylinders
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Engine Equipment That Uses Special Cycles (AREA)
- Magnetic Bearings And Hydrostatic Bearings (AREA)
Abstract
A Stirling engine comprising: a crank case (1) with a crank shaft (2) arranged therein, a displacer cylinder (3) with a reciprocatingly arranged displacer piston (4) therein, said displacer piston (4) being connected to said crank shaft (2) via a connecting rod (5) extending through a first end of said displacer cylinder (3), and wherein the displacer cylinder (3) defines a hot chamber (6) and a cool chamber (7) separated by the displacer piston (4), a working cylinder (8) defining a working cylinder chamber (11) with a reciprocatingly arranged working piston (9) therein, said working piston (9) being connected to said crank shaft (2) via a connecting rod (10) extending through a first end of the working cylinder (8), a heater device (14), arranged at a second end of said displacer cylinder (3) opposite to said first end and configured to heat a working gas which is present in the hot chamber (6) of the displacer cylinder (3) and in fluid communication with the working cylinder chamber (11) through a working gas channel which comprises a first heat exchanger (16) extending from a cylinder head (19) of the displacer cylinder (3) into the heater device (14), a second heat exchanger (17) formed by a regenerator arranged outside the heater device (14), and a transition flow element (22) provided between said second heat exchanger (17) and the working cylinder (8). The transition flow element (22) comprises a tubular body that defines a channel (23), and, inside said channel (23), there is provided a flow control element (24) configured to control the volume available to the working gas in said channel (23) depending on the working gas pressure in said channel (23).
Description
Stirling engine comprising a transition flow element TECHNICAL FIELD The present invention relates to a Stirling engine comprising: - a crank case with a crank shaft arranged therein, - a displacer cylinder with a reciprocatingly arranged displacer piston therein, said displacer piston being connected to said crank shaft via a connecting rod extending through a first end of said displacer cylinder, and wherein the displacer cylinder defines a hot chamber and a cool chamber separated by the displacer piston, - a working cylinder defining a working cylinder chamber with a reciprocatingly arranged working piston therein, said working piston being connected to said crank shaft via a connecting rod extending through a first end of the working cylinder, - a heater device, arranged at a second end of said displacer cylinder opposite to said first end and configured to heat a working gas which is present in the hot chamber of the displacer cylinder and in fluid communication with the working cylinder chamber through a working gas channel which comprises - a first heat exchanger extending from a cylinder head of the displacer cylinder into the heater device, - a second heat exchanger formed by a regenerator arranged outside the heater device, and - a transition flow element provided between said second heat exchanger and the working cylinder.
BACKGROUND External combustion engines of Stirling type are well known. They may be of three different types, which are named alpha, beta and gamma and differ from each other with regard to how the displacer cylinder, the working cylinder and the displacer piston and the working piston are arranged in relation to each other and to the crank shaft that is driven by the working piston.
Essential to the function of a Stirling engine is that a working medium is heated, preferably by a burner flame in a combustion chamber. During heating thereof, the working gas is conducted through a heat exchanger that may comprise one or more tubes that extend from the hot chamber of the displacer cylinder into the combustion chamber, and further out of the combustion chamber towards a regenerator. The regenerator is located outside the combustion chamber and is the individual component that distinguishes Stirling engines from other types of external combustion engines. After the regenerator, as seen in a flow direction of the working gas from the hot chamber of the displacer cylinder to the working cylinder, there may also be provided a cooler which is configured to cool the working fluid.
Between the cooler and the working cylinder there is provided a transition flow element, i.e. a channel, which has a certain volume. As, during the working cycle of the engine, the working gas moves in a direction from the working cylinder towards the displacer cylinder, the volume of the transition flow element will define a dead volume that affects the yield of engine negatively.
It is an object of the present invention to present a Stirling engine that reduces the negative effects of dead volumes appearing in a working gas channel between the displacer cylinder and the working cylinder during operation of the Stirling engine.
SUMMARY OF THE INVENTION The object of the invention is achieved by means of the initially defined Stirling engine, which is characterised in that the transition flow element comprises a tubular body that defines a first channel, and that, inside said first channel, there is provided a flow control element configured to control the volume available to the working gas in said first channel depending on the working gas pressure in said first channel. At suitable occasions during operation of the engine, the volume available to the working gas in said first channel, and thereby the dead volume, may thus be reduced.
According to the present disclosure, said flow control element is attached to a non-flexible tube which defines a second channel extending in the longitudinal direction of the first channel defined by the tubular body of the transition flow element. The non-flexible tube extends through the flow control element, and it guarantees that working gas can pass through the flow control element even the circumstances that, due to low working gas pressure in the first channel, the flow control element expands so much that it completely fills the cross-section of the first channel defined by the tubular body of the transition flow element. If the latter situation appears before the working piston reaches its upper dead point, working gas may still be transported through the channel of the transition flow element thanks to the provision of said non-flexible tube. The term "non flexible" primarily means the tube is not flexible to such an extent that it would be so deformed by the pressure from the flow control element that it will not be able of defining the channel through which it will conduct the working gas. Preferably, "non-flexible" also means that the tube is able of acting as a rigid holder by which the flow control element is supported. Preferably, the flow control element is arranged as a sleeve on the outer periphery of the non-flexible tube.
According to one embodiment, the flow control element is configured to reduce the volume available to the working gas in said first channel as an answer to a reduction of the pressure in said first channel. As, during operation of the engine, the working piston approaches its upper dead point, the pressure in the transition flow element will decrease. The control element is thus configured to reduce the volume available to the working gas in the first channel in connection the working piston's approach of its upper dead point.
According to one embodiment, the flow control element comprises a collapsible body filled with a gas. The pressure of the gas inside the collapsible body is such that, when the working gas pressure in said first channel defined by the transition flow element is reduced to the extent that can be expected upon motion of the working piston towards its upper dead point, the collapsible body will expand and thereby reduce the volume available to the working gas in said first channel. In other words, at least some of the working gas will be forced towards the displacer cylinder and will be prevented from occupying space in said first channel.
Preferably, the collapsible body is configured so as to expand to such an extent that it contacts the inner periphery of the tubular body defining the first channel when the working gas pressure reaches a minimum in the first channel, preferably when the working piston is in the region of its upper dead point.
According to one embodiment, the flow control element is a tubular body. Preferably, the tubular body has a longitudinal axis which is coaxial with a longitudinal axis of said first channel.
According to one embodiment, the flow control element extends along a major part of the length of said first channel. In other words, the flow control element has a length which is at least 50%, preferably at least 75%, of the length defined by said first channel, at least when the control element is in its most expanded state. The flow control element is configured to fill at least 75% of the volume of said first channel when in a most expanded state during operation of the engine.
According to one embodiment, said non-flexible tube is coaxial with said first channel of the transition flow element in which it is provided. For this purpose, one or more holder elements extending from an inner periphery of the tubular body that defines the first channel of the transition flow element.
According to one embodiment, the flow control element comprises a one way valve provided in the second channel defined by said non-flexible tube, wherein the one way valve is configured to allow working gas to flow through said second channel in a direction from the working cylinder towards the displacer cylinder when being in an open state.
According to one embodiment, the Stirling engine comprises a third heat exchanger formed by a cooler arranged between the regenerator and the working cylinder chamber, and that said transition flow element is provided between said third heat exchanger and the working cylinder.
Further features and advantages of the present invention will be presented in the following detailed description of an embodiment of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention are shown in the annexed drawing, on which: Fig. 1 is a view from above of a Stirling engine according to the invention provided with a schematically shown heater device, Fig. 2 is a view corresponding to fig. 1, but with the heater device removed from the rest of the engine, Fig. 3 is a cross-section according to I-I in fig. 1, still with the heater device shown schematically, Fig. 4 is an end view of a transition flow element with a flow control element arranged inside, in a first state, Fig. 5 is a cross-section according to IV-IV in fig. 4, Fig. 6 is and end view corresponding to fig. 4, but with the flow control element in a second state, and Fig. 7 is a cross-section according to VI-VI in fig. 6.
DETAILED DESCRIPTION Figs. 1-3 show an embodiment of a Stirling engine according to the present invention. The Stirling engine shown is of gamma type and comprises a crank case 1 with a crank shaft 2 arranged therein, and a displacer cylinder 3 with a reciprocatingly arranged displacer piston 4 therein. The displacer piston 4 is connected to the crank shaft 2 via a connecting rod 5 extending through a first end of said displacer cylinder 3. During operation of the Stirling engine, the displacer cylinder 3 defines a hot chamber 6 and a cool chamber 7 separated by the displacer piston 4.
The Stirling engine further comprises a working cylinder 8 with a reciprocatingly arranged working piston 9 therein, said working piston 9 being connected to the crank shaft 2 via a connecting rod 10 extending through a first end of the working cylinder 8. A working cylinder chamber 11 defined by the working cylinder 8 is divided by the working piston 9 into a first part 12, through which said connecting rod 10 extends, and a second part 13 configured to house a working gas during operation of the Stirling engine. The second part 13 of the working cylinder chamber 11 is in fluid communication with the hot chamber 6 of the displacer cylinder 3 for the transportation of the working gas between said second part 13 of the working chamber 11 and the hot chamber 6 of the displacer cylinder 3 during operation of the engine.
To the crank shaft 2 there is connected an electric generator 48, via which electric power can be transferred from the Stirling engine.
A heater device 14 is arranged at a second end of the displacer cylinder opposite to said first end and configured to heat a working gas which is present in the hot chamber 6 of the displacer cylinder 3 and which is in fluid communication with the second part 13 of the working cylinder chamber 11. 1 the embodiment shown the heater device 14 comprises a combustion chamber 15 which is arranged at the second end of said displacer cylinder 3 opposite to said first end.
Furthermore, the Stirling engine comprises a first heat exchanger 16 and a second heat exchanger 17. The first heat exchanger 16 comprises plurality of tubes 18 that extend from a displacer cylinder head 19 provided at said second end of the displacer cylinder 3 into the combustion chamber 15 and out of the combustion chamber 15 to the second heat exchanger 17. The second heat exchanger 17 is comprised by a regenerator provided outside the combustion chamber 15 and outside the displacer cylinder 3. In the embodiment shown the engine also comprises a third heat exchanger 20 formed by a cooler arranged between the regenerator 17 and the working cylinder chamber 11, and a transition flow element 22 provided between the third heat exchanger 20 and the working cylinder 8. The cooler 20 comprises a body with channels 46 for the conduction of the working gas through said body and with further channels 47 which form part of a cooling medium circuit.
The hot chamber 6 defined by the displacer cylinder 3 is in fluid communication with a second end, i.e. the above-defined second part 13, of the working cylinder chamber 11 through a channel comprising the first heat exchanger 16, the second heat exchanger 17, the third heat exchanger 20, and the transition flow element 22. In the embodiment shown here, there is also provided an intermediate flow element 21 between the first heat exchanger 16 and the second heat exchanger 17 acting as an adapter between the heat exchangers.
During operation of the Stirling engine, the working gas will travel back and forth between the hot chamber 6 of the displacer cylinder 3 and the second part 13 of the working cylinder chamber 11 in accordance with the principles of a Stirling engine. The transition flow element 22 comprises a tubular body that defines a first channel 23. Inside said first channel 23, there is provided a flow control element 24 configured to control the volume available to the working gas in said first channel 23 depending on the working gas pressure in said first channel 23. The flow control element 24 comprises a collapsible body 25 filled with a gas.
As is further shown in detail in figs. 4-7, the collapsible body 25 has the shape of a tube having a longitudinal axis which is coaxial with a longitudinal axis of the first channel 23 in which it is located. The flow control element 24 also comprises a non-flexible tube 26 which is provided in the centre of the collapsible body 25, and coaxially therewith. The non-flexible tube 26 is rigid enough to withstand an outer pressure from the collapsible body 25 caused by the gas pressure in the latter without collapsing. The non-flexible tube 26 guarantees that there will be a conduit for working gas to flow through from the working cylinder 8 towards the displacer cylinder 3 in said first channel 23 irrespectively of how much the collapsible body 25 expands and fills the first channel 23 in which it is located. The non-flexible tube 26 is held in position by a holder element 27 that in one end is connected to the tubular body of the transition flow element 22 and in another end is connected to the non-flexible tube 26.
In figs. 4 and 5, the pressure in the first channel 23 is high enough to compress the collapsible body 25 such that it does not remarkably reduce the volume of the first channel 23. In figs. 6 and 7, the pressure in the first channel 23 is reduced to such an extent that the gas pressure inside the collapsible body 25 expands the latter such that it fills up the volume between the non-flexible tube 26 and the inner periphery of the transition flow element 22. The pressure inside the collapsible body 25 is set such that this state typically will be obtained as the working piston approaches its upper dead point during the operation cycle of the engine. The second channel 28 inside the non-flexible tube will, however, enable further working gas to pass through the transition flow element, also when the collapsible body 25 is fully expanded.
Claims (7)
1. A Stirling engine comprising: - a crank case (1) with a crank shaft (2) arranged therein, - a displacer cylinder (3) with a reciprocatingly arranged displacer piston (4) therein, said displacer piston (4) being connected to said crank shaft (2) via a connecting rod (5) extending through a first end of said displacer cylinder (3), and wherein the displacer cylinder (3) defines a hot chamber (6) and a cool chamber (7) separated by the displacer piston (4), - a working cylinder (8) defining a working cylinder chamber (11) with a reciprocatingly arranged working piston (9) therein, said working piston (9) being connected to said crank shaft (2) via a connecting rod (10) extending through a first end of the working cylinder (8), - a heater device (14), arranged at a second end of said displacer cylinder (3) opposite to said first end and configured to heat a working gas which is present in the hot chamber (6) of the displacer cylinder (3) and in fluid communication with the working cylinder chamber (11) through a working gas channel which comprises - a first heat exchanger (16) extending from a cylinder head (19) of the displacer cylinder (3) into the heater device (14), - a second heat exchanger (17) formed by a regenerator arranged outside the heater device (14), and - a transition flow element (22) provided between said second heat exchanger (17) and the working cylinder (8), said Stirling engine being characterised in that the transition flow element (22) comprises a tubular body that defines a first channel (23), and that, inside said first channel (23), there is provided a flow control element (24) configured to control the volume available to the working gas in said first channel (23) depending on the working gas pressure in said first channel (23), said flow control element (24) is attached to a non-flexible tube (26) which defines a second channel (28) extending in the longitudinal direction of the first channel (23) defined by the tubular body of the transition flow element (22).
2. A Stirling engine according to claim 1, characterised in that the flow control element (24) is configured to reduce the volume available to the working gas in said first channel (23) as an answer to a reduction of the working gas pressure in said first channel (23).
3. A Stirling engine according to claim 1 or 2, characterised in that the flow control element (24) comprises a collapsible body (25) filled with a gas.
4. A Stirling engine according to any one of claim 1-3, characterised in that the flow control element (24) is a tubular body.
5. A Stirling engine according to any one of claims 1-4, characterised in that the flow control element (24) extends along a major part of the length of said first channel (23).
6. A Stirling engine according to claim 1, characterised in that said non-flexible tube (26) is coaxial with said first channel (23) in which it is provided.
7. A Stirling engine according to any one of claims 1-6, characterised in that it comprises a third heat exchanger (20) formed by a cooler arranged between the regenerator (17) and the working cylinder chamber (11), and that said transition flow element (22) is provided between said third heat exchanger (20) and the working cylinder (11).
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE1850002A SE541814C2 (en) | 2018-01-02 | 2018-01-02 | Stirling engine comprising a transition flow element |
| PCT/SE2018/051356 WO2019135699A1 (en) | 2018-01-02 | 2018-12-20 | Stirling engine comprising transition flow element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE1850002A SE541814C2 (en) | 2018-01-02 | 2018-01-02 | Stirling engine comprising a transition flow element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| SE1850002A1 SE1850002A1 (en) | 2019-07-03 |
| SE541814C2 true SE541814C2 (en) | 2019-12-17 |
Family
ID=67143939
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| SE1850002A SE541814C2 (en) | 2018-01-02 | 2018-01-02 | Stirling engine comprising a transition flow element |
Country Status (2)
| Country | Link |
|---|---|
| SE (1) | SE541814C2 (en) |
| WO (1) | WO2019135699A1 (en) |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6125955A (en) * | 1984-07-16 | 1986-02-05 | Matsushita Electric Ind Co Ltd | Stirling engine |
| CN1040147C (en) * | 1988-12-16 | 1998-10-07 | 三洋电机株式会社 | Heat pump system |
| JPH0552661U (en) * | 1991-12-05 | 1993-07-13 | ダイキン工業株式会社 | Stirling engine heating device |
| JPH06101922A (en) * | 1992-09-17 | 1994-04-12 | Daikin Ind Ltd | Vuilleumier heat pump apparatus |
| KR0152291B1 (en) * | 1993-06-10 | 1998-11-02 | 김광호 | Cooling/heating device of vulmire heat pump |
| JPH09152211A (en) * | 1995-11-30 | 1997-06-10 | Sanyo Electric Co Ltd | Piston for external combustion engine |
| DE10110446A1 (en) * | 2001-03-05 | 2002-09-19 | Solo Kleinmotoren Gmbh | Pistons and cylinders for a Stirling engine |
-
2018
- 2018-01-02 SE SE1850002A patent/SE541814C2/en unknown
- 2018-12-20 WO PCT/SE2018/051356 patent/WO2019135699A1/en active Application Filing
Also Published As
| Publication number | Publication date |
|---|---|
| SE1850002A1 (en) | 2019-07-03 |
| WO2019135699A1 (en) | 2019-07-11 |
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