WO2008075015A1 - An annular regenerator assembly - Google Patents

An annular regenerator assembly Download PDF

Info

Publication number
WO2008075015A1
WO2008075015A1 PCT/GB2007/004837 GB2007004837W WO2008075015A1 WO 2008075015 A1 WO2008075015 A1 WO 2008075015A1 GB 2007004837 W GB2007004837 W GB 2007004837W WO 2008075015 A1 WO2008075015 A1 WO 2008075015A1
Authority
WO
WIPO (PCT)
Prior art keywords
regenerator
assembly
sleeves
annular
sleeve
Prior art date
Application number
PCT/GB2007/004837
Other languages
French (fr)
Inventor
Christopher Hughes
Original Assignee
Microgen Engine Corporation Holding B.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Microgen Engine Corporation Holding B.V. filed Critical Microgen Engine Corporation Holding B.V.
Priority to EP07848574A priority Critical patent/EP2122146A1/en
Priority to JP2009542197A priority patent/JP2010513786A/en
Publication of WO2008075015A1 publication Critical patent/WO2008075015A1/en

Links

Classifications

    • 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
    • F02G1/053—Component parts or details
    • F02G1/057—Regenerators
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D17/00—Regenerative heat-exchange apparatus in which a stationary intermediate heat-transfer medium or body is contacted successively by each heat-exchange medium, e.g. using granular particles
    • F28D17/02—Regenerative heat-exchange apparatus in which a stationary intermediate heat-transfer medium or body is contacted successively by each heat-exchange medium, e.g. using granular particles using rigid bodies, e.g. of porous material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D17/00—Regenerative heat-exchange apparatus in which a stationary intermediate heat-transfer medium or body is contacted successively by each heat-exchange medium, e.g. using granular particles
    • F28D17/02—Regenerative heat-exchange apparatus in which a stationary intermediate heat-transfer medium or body is contacted successively by each heat-exchange medium, e.g. using granular particles using rigid bodies, e.g. of porous material
    • F28D17/023—Sealing means

Definitions

  • the present invention relates to an annular regenerator assembly.
  • the annular regenerator assembly has been designed for a Stirling machine, more specifically a linear free piston Stirling engine.
  • the regenerator can be used in any situation where an annular regenerator is required.
  • regenerators are well known in the field of Stirling engines. A number of different regenerator materials may be used and can be broadly categorised as wire, foil, gauze or foam type materials.
  • the current method being employed by the applicant is to pack random wire into the annular regenerator space within the Stirling engine head after internal acceptor fins have been brazed in place. This is a labour intensive process which is not suited to cost-effective mass production.
  • regenerator assembly which is bounded on its inner and outer surfaces by inner and outer sleeves respectively. These are provided for a number of reasons, for example, to keep the regenerator elements in place.
  • JP 62-082264 provides 0-rings which seal respective sleeves with the cylinder and casing.
  • annular regenerator assembly comprising an annular regenerator medium bounded on inner and outer surfaces by inner and outer sleeves respectively, at least one of the sleeves having a bend which forms an annular sealing projection extending around the sleeve and projecting in a direction away from the regenerator medium.
  • the present invention provides a simple regenerator structure which is suitable for mass production and can be used in a high temperature engine. Also, it does not rely on close tolerances between the sleeves and surrounding components, which can be vulnerable to problems with differential thermal expansion.
  • the regenerator assembly can be manufactured as a single component which can then simply be pushed into place in the engine head with the annular sealing projection providing a seal between the engine cylinder or the engine casing.
  • the sealing projection may be provided on only one of the sleeves, with some alternative sealing mechanism being provided on the other. However, preferably, a respective annular sealing projection is provided on each of the sleeves.
  • the invention will function with a single projection on each sleeve. However, preferably, there is more than one annular sealing projection on the or each sleeve, each formed by a respective bend in the sleeve.
  • the invention also extends to a method of forming an annular regenerator assembly according to the first aspect of the present invention.
  • This method is broadly defined as comprising the steps of assembling inner and outer annular sleeves; bending at least one of the sleeves to form the annular sealing projection extending around the sleeve; and filling the assembly with the regenerator medium.
  • the method also preferably includes the steps of fitting an end cap covering the space between the sleeves at one end prior to the filling step; and fitting an end cap over the opposite end of the regenerator assembly after the filling step.
  • the bending step may be performed either before or after the assembly is filled with the regenerator medium.
  • the method may also include the step of removing the end caps prior to assembly in an engine.
  • FIG. 1 is an exploded perspective view of the regenerator with a portion being shown cut away;
  • Fig. 2 is a partial perspective with a portion cut away showing the regenerator assembly inserted into a Stirling engine .
  • the regenerator comprises a regenerating material 1 having an annular configuration. This may be any suitable material such as wire, foil, gauze or foam.
  • the inner surface of the regenerator material 1 is bounded by an inner cylindrical sleeve 2 with the outer surface bounded by an outer cylindrical sleeve 3.
  • Each sleeve is provided with a pair of bent portions 4 which are spaced from the ends and extend circumferentially around the sleeve. These bent portions form a convolute portion which provides an annular sealing lip surround the sleeve.
  • Upper 5 and lower 6 end caps are fitted over the upper and lower ends respectively of the assembly. They have inner 7 and outer 8 lips to help locate the caps over the ends of the regenerator assembly.
  • the sleeves 2, 3 are held together in the lower cap 6.
  • the regenerator material is then packed into the annular space formed between the cylinders to the specified density before the upper cap 5 is fitted in place.
  • the end caps retain the contents of the assembly during transportation and also provide structural integrity.
  • the bent portions may be formed prior to assembly, for example, by a bulge-forming process as described in US 6,044,678. Alternatively, these portions may be formed after the regenerator is assembled. In this case, the end caps would be removed and the forming process would compress the two sleeves together along most of their lengths leaving only circumferential gaps to form the bent portions as uncompressed rings.
  • the cylinders are thereby compressed against the internal packing, ensuring that any packing voids which remain after the filling process are eliminated. If required, another set of end caps with dimensions matching the compressed shape are then installed for transportation. If a filling material such as foil is used, end caps may not be needed for transportation.
  • regenerator material could be used with random steel wire as the regenerator material .
  • it could also be used with a more rigid regenerator material, such as foil, gauze or foam.
  • regenerators based on these more rigid materials benefit from such a sleeved design which uses the integral annular sealing rings.
  • Fig. 2 shows a portion of the head of the engine.
  • the engine comprises a casing 10 provided at its top end by an annular arrangement of acceptor fins 12.
  • the end caps 5, 6 Prior to being assembled into the engine, the end caps 5, 6 are removed. The assembly is then pushed - G -
  • the annular sealing projections 4 compress as they fit into the engine, deforming the sleeves 2, 3 to an acceptable extent so as to ensure that the seal is formed even if the surface against which the seal is being formed is uneven or non-cylindrical (to within the manufacturing tolerances) .
  • Sintered rings may also be required above and below the cartridge, if it contains random wire to prevent the wire particles from spreading into the body of the engine.
  • These sintered rings (with suitable fixing means, e.g., locating lips as shown) could be used instead of the end caps 5, 6 to form a permanently sealed component and avoid the need for additional components and installation operations.
  • the inner and outer sealing projections 4 push securely against the casing 10 and cylinder 11 to form a seal and prevent gases from bypassing the regenerator material during operation.
  • the sleeves, casing and cylinder, in the example described, are all manufactured from stainless steel so that they are no differences in thermal expansion and the seal will be maintained at all operating temperatures.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Dispersion Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)
  • Gasket Seals (AREA)

Abstract

An annular regenerator assembly comprising an annular regenerator medium (1) bounded on inner and outer surfaces by inner (2) and outer (3) sleeves respectively. At least one of the sleeves has a bend (4) to form an annular sealing projection extending around the sleeve and projecting in a direction away from the regenerator medium.

Description

AN ANNULAR REGENERATOR ASSEMBLY
The present invention relates to an annular regenerator assembly.
The annular regenerator assembly has been designed for a Stirling machine, more specifically a linear free piston Stirling engine. However, the regenerator can be used in any situation where an annular regenerator is required.
Annular regenerators are well known in the field of Stirling engines. A number of different regenerator materials may be used and can be broadly categorised as wire, foil, gauze or foam type materials.
The current method being employed by the applicant is to pack random wire into the annular regenerator space within the Stirling engine head after internal acceptor fins have been brazed in place. This is a labour intensive process which is not suited to cost-effective mass production.
It is well known in the art (for example, from JP 62- 082264, US 6,862,883 and US 2006/0118273) to have a regenerator assembly which is bounded on its inner and outer surfaces by inner and outer sleeves respectively. These are provided for a number of reasons, for example, to keep the regenerator elements in place.
It is very important to the efficient operation of an engine that gas flow is unable to bypass the regenerator. To this end, JP 62-082264 provides 0-rings which seal respective sleeves with the cylinder and casing.
Such a design has a number of drawbacks. The use of 0- rings means that it is unsuitable for use in high temperature applications, and increases the number of components required.
According to the present invention, there is provided an annular regenerator assembly comprising an annular regenerator medium bounded on inner and outer surfaces by inner and outer sleeves respectively, at least one of the sleeves having a bend which forms an annular sealing projection extending around the sleeve and projecting in a direction away from the regenerator medium.
The present invention provides a simple regenerator structure which is suitable for mass production and can be used in a high temperature engine. Also, it does not rely on close tolerances between the sleeves and surrounding components, which can be vulnerable to problems with differential thermal expansion.
The regenerator assembly can be manufactured as a single component which can then simply be pushed into place in the engine head with the annular sealing projection providing a seal between the engine cylinder or the engine casing.
In the broadest sense, the sealing projection may be provided on only one of the sleeves, with some alternative sealing mechanism being provided on the other. However, preferably, a respective annular sealing projection is provided on each of the sleeves.
The invention will function with a single projection on each sleeve. However, preferably, there is more than one annular sealing projection on the or each sleeve, each formed by a respective bend in the sleeve.
The invention also extends to a method of forming an annular regenerator assembly according to the first aspect of the present invention. This method is broadly defined as comprising the steps of assembling inner and outer annular sleeves; bending at least one of the sleeves to form the annular sealing projection extending around the sleeve; and filling the assembly with the regenerator medium.
If the regenerator medium is of the type which is likely to have loose elements, the method also preferably includes the steps of fitting an end cap covering the space between the sleeves at one end prior to the filling step; and fitting an end cap over the opposite end of the regenerator assembly after the filling step.
The bending step may be performed either before or after the assembly is filled with the regenerator medium.
The method may also include the step of removing the end caps prior to assembly in an engine.
An example of a regenerator assembly in accordance with the present invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is an exploded perspective view of the regenerator with a portion being shown cut away; and
Fig. 2 is a partial perspective with a portion cut away showing the regenerator assembly inserted into a Stirling engine .
The regenerator comprises a regenerating material 1 having an annular configuration. This may be any suitable material such as wire, foil, gauze or foam. The inner surface of the regenerator material 1 is bounded by an inner cylindrical sleeve 2 with the outer surface bounded by an outer cylindrical sleeve 3. Each sleeve is provided with a pair of bent portions 4 which are spaced from the ends and extend circumferentially around the sleeve. These bent portions form a convolute portion which provides an annular sealing lip surround the sleeve.
Upper 5 and lower 6 end caps are fitted over the upper and lower ends respectively of the assembly. They have inner 7 and outer 8 lips to help locate the caps over the ends of the regenerator assembly.
In order to assemble the regenerator assembly, the sleeves 2, 3 are held together in the lower cap 6. The regenerator material is then packed into the annular space formed between the cylinders to the specified density before the upper cap 5 is fitted in place. The end caps retain the contents of the assembly during transportation and also provide structural integrity. The bent portions may be formed prior to assembly, for example, by a bulge-forming process as described in US 6,044,678. Alternatively, these portions may be formed after the regenerator is assembled. In this case, the end caps would be removed and the forming process would compress the two sleeves together along most of their lengths leaving only circumferential gaps to form the bent portions as uncompressed rings. The cylinders are thereby compressed against the internal packing, ensuring that any packing voids which remain after the filling process are eliminated. If required, another set of end caps with dimensions matching the compressed shape are then installed for transportation. If a filling material such as foil is used, end caps may not be needed for transportation.
The method could be used with random steel wire as the regenerator material . However, it could also be used with a more rigid regenerator material, such as foil, gauze or foam. One of the benefits of this design comes when it is used with more rigid materials. These materials do not naturally fill the irregular space which forms the regenerator passageway in the same way that random wire does. Therefore, regenerators based on these more rigid materials benefit from such a sleeved design which uses the integral annular sealing rings.
The assembly of the regenerator assembly into a Stirling engine is shown in Fig. 2, which shows a portion of the head of the engine. The engine comprises a casing 10 provided at its top end by an annular arrangement of acceptor fins 12. Prior to being assembled into the engine, the end caps 5, 6 are removed. The assembly is then pushed - G -
into the engine head. The annular sealing projections 4 compress as they fit into the engine, deforming the sleeves 2, 3 to an acceptable extent so as to ensure that the seal is formed even if the surface against which the seal is being formed is uneven or non-cylindrical (to within the manufacturing tolerances) .
Sintered rings may also be required above and below the cartridge, if it contains random wire to prevent the wire particles from spreading into the body of the engine. These sintered rings (with suitable fixing means, e.g., locating lips as shown) could be used instead of the end caps 5, 6 to form a permanently sealed component and avoid the need for additional components and installation operations.
The inner and outer sealing projections 4 push securely against the casing 10 and cylinder 11 to form a seal and prevent gases from bypassing the regenerator material during operation. The sleeves, casing and cylinder, in the example described, are all manufactured from stainless steel so that they are no differences in thermal expansion and the seal will be maintained at all operating temperatures.

Claims

CLAIMS :
1. An annular regenerator assembly comprising an annular regenerator medium bounded on inner and outer surfaces by inner and outer sleeves respectively, at least one of the sleeves having a bend to form an annular sealing projection extending around the sleeve and projecting in a direction away from the regenerator medium.
2. An assembly according to claim 1, wherein a respective annular sealing projection is provided on each of the sleeves .
3. An assembly according to claim 1 or claim 2, wherein there is more than one annular sealing projection on the or each sleeve, each projection formed by a respective bend in the sleeve.
4. A method of assembling an assembly according to any of the preceding claims comprising the steps of assembling the inner and outer annular sleeves; bending at least one of the sleeves to form an annular sealing projection extending around the sleeve; and filling the assembly with the regenerator medium.
5. A method according to claim 1, further comprising fitting an end cap covering the space between the sleeves at one end prior to the filling step and fitting an end cap over the opposite end of the regenerator assembly after the filling step.
6. A method according to claim 5, further comprising the step of removing the end caps prior to assembly in an engine .
PCT/GB2007/004837 2006-12-20 2007-12-17 An annular regenerator assembly WO2008075015A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP07848574A EP2122146A1 (en) 2006-12-20 2007-12-17 An annular regenerator assembly
JP2009542197A JP2010513786A (en) 2006-12-20 2007-12-17 Annular regenerator assembly

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0625483.3 2006-12-20
GBGB0625483.3A GB0625483D0 (en) 2006-12-20 2006-12-20 An annular regenerator assembly

Publications (1)

Publication Number Publication Date
WO2008075015A1 true WO2008075015A1 (en) 2008-06-26

Family

ID=37734575

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2007/004837 WO2008075015A1 (en) 2006-12-20 2007-12-17 An annular regenerator assembly

Country Status (5)

Country Link
EP (1) EP2122146A1 (en)
JP (1) JP2010513786A (en)
KR (1) KR20090125750A (en)
GB (1) GB0625483D0 (en)
WO (1) WO2008075015A1 (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6282264A (en) * 1985-10-04 1987-04-15 Mitsubishi Electric Corp Heat exchanger for stirling engine
US5469709A (en) * 1993-06-18 1995-11-28 Samsung Electronics Co., Ltd. Regenerator for Vuilleumier heat pump
US20040088973A1 (en) * 2000-11-30 2004-05-13 Shozo Tanaka Stirling engine

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6282264A (en) * 1985-10-04 1987-04-15 Mitsubishi Electric Corp Heat exchanger for stirling engine
US5469709A (en) * 1993-06-18 1995-11-28 Samsung Electronics Co., Ltd. Regenerator for Vuilleumier heat pump
US20040088973A1 (en) * 2000-11-30 2004-05-13 Shozo Tanaka Stirling engine

Also Published As

Publication number Publication date
GB0625483D0 (en) 2007-01-31
KR20090125750A (en) 2009-12-07
JP2010513786A (en) 2010-04-30
EP2122146A1 (en) 2009-11-25

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