WO1999028685A1 - Ensemble de piston deplaceur pour un systeme a cycle stirling - Google Patents

Ensemble de piston deplaceur pour un systeme a cycle stirling Download PDF

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Publication number
WO1999028685A1
WO1999028685A1 PCT/US1997/021666 US9721666W WO9928685A1 WO 1999028685 A1 WO1999028685 A1 WO 1999028685A1 US 9721666 W US9721666 W US 9721666W WO 9928685 A1 WO9928685 A1 WO 9928685A1
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WO
WIPO (PCT)
Prior art keywords
displacer
motor
compressor
gap
electric motor
Prior art date
Application number
PCT/US1997/021666
Other languages
English (en)
Inventor
Misha Hiterer
Mark Kushnir
Original Assignee
Medis El Ltd.
Friedman, Mark, M.
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 Medis El Ltd., Friedman, Mark, M. filed Critical Medis El Ltd.
Priority to EP97949629A priority Critical patent/EP1042637A4/fr
Priority to JP2000523504A priority patent/JP2001525530A/ja
Priority to KR10-2000-7005843A priority patent/KR100516236B1/ko
Priority to PCT/US1997/021666 priority patent/WO1999028685A1/fr
Priority to AU35876/99A priority patent/AU3587699A/en
Priority to TW087109470A priority patent/TW429299B/zh
Publication of WO1999028685A1 publication Critical patent/WO1999028685A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/14—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle
    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K33/00—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system
    • H02K33/16—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system with polarised armatures moving in alternate directions by reversal or energisation of a single coil system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/001—Gas cycle refrigeration machines with a linear configuration or a linear motor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/14—Compression machines, plants or systems characterised by the cycle used 
    • F25B2309/1421—Pulse-tube cycles characterised by details not otherwise provided for
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/14—Compression machines, plants or systems characterised by the cycle used 
    • F25B2309/1428—Control of a Stirling refrigeration machine
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K16/00—Machines with more than one rotor or stator

Definitions

  • the present invention relates to Stirling cycle machines and, in particular, it concerns Stirling cycle system having displacer driven by a 5 synchronous linear motor with a magnetic spring.
  • Stirling cycle systems contain two essential moving parts, both of which execute reciprocating motion.
  • One of these parts usually known as the "displacer”
  • the displacer is typically implemented as a plunger movable with clearance along a cylinder. I ⁇ This serves to transfer a mass of gas in alternate directions between the two ends of the cylinder.
  • the displacer is connected to a compressor which generates pulsating pressure within the gas. By driving the displacer at the same frequency as the compressor, but at a certain phase difference therefrom, the system operates as a heat pump with heat being removed from one end of the 15 displacer. In this manner, Stirling cycle systems can be used as the basis for a range of refrigeration systems.
  • phase relationship between the compressor and the displacer In order to maintain efficient operation of a Stirling cycle system, the phase relationship between the compressor and the displacer must be optimized.
  • the phase relation is most commonly maintained by a mechanical 20 linkage between the compressor and displacer.
  • it is very difficult to make such a linkage so as to allow adjustment of either the phase relation or the amplitude.
  • a mechanical linkage tends to transmit vibration between the two parts of the system, rendering both the linkage itself and the system as a whole unreliable.
  • 25 ⁇ alternative approach is a split structure employing a "passive" displacer assembly in which the displacer acts as a free piston.
  • the Davey machine has a number of advantages. However, the efficiency of the system is severely limited by motor structure employed.
  • the motor is shown as a single cylindrical coil moving axially within the cylindrical gap of a permanent magnet circuit.
  • the motor structure described provides low efficiency and has no self-centering properties. Such a system also requires sliding contacts which are unreliable.
  • the displacer of the Davey machine in common with all other Stirling displacers, requires various spring elements to return the displacer to its neutral position.
  • Such mechanical spring elements present numerous design problems, being difficult to adjust, intensifying mechanical wear, and increasing acoustic noise.
  • the present invention is a Stirling cycle displacer driven by a synchronous linear motor with a magnetic spring, and a Stirling cycle system including the same.
  • a displacer assembly for a Stirling cycle system comprising: (a) a displacer; and (b) a synchronous linear electric motor operatively connected so as to drive the displacer, the electric motor having an axis of movement, the electric motor including: (i) at least one stator assembly having first and second soft-magnetic pole pieces defining therebetween a gap, a width of the gap being oriented perpendicular to the axis, the stator assembly being constructed so as to generate a magnetic field aligned primarily parallel to the width of the gap, and (ii) at least one compound permanent magnet system located within the gap, the compound permanent magnet system including a first section magnetized in a first direction parallel to the width of the gap and a second section axially displaced from the first section magnetized in a direction opposite to the first direction
  • a Stirling cycle system comprising: (a) a compressor; (b) a displacer; and (c) a synchronous linear electric motor operatively connected so as to drive the displacer, wherein the electric motor is constructed so as to provide a magnetic spring such that, when no power is supplied to the motor, the displacer returns to a predefined rest position.
  • the electric motor has an axis of movement, the electric motor including: (a) at least one stator assembly having first and second soft-magnetic pole pieces defining therebetween a gap, a width of the gap being oriented perpendicular to the axis, the stator assembly being constructed so as to generate a magnetic field aligned primarily parallel to the width of the gap; and (b) at least one compound permanent magnet system located within the gap, the compound permanent magnet system including a first section magnetized in a first direction parallel to the width of the gap and a second section axially displaced from the first section magnetized in a direction opposite to the first direction.
  • the compressor includes at least one synchronous linear electric motor, referred to as the
  • compressor motor the compressor motor being constructed so as to provide a magnetic spring such that, when no power is supplied to the compressor motor, the compressor returns to a predefined rest state.
  • the compressor motor includes: (a) at least one stator assembly having first and second soft- magnetic pole pieces defining therebetween a gap, a width of the gap being oriented perpendicular to the axis of movement of the motor, the stator assembly being constructed so as to generate a magnetic field aligned primarily parallel to the width of the gap; and (b) at least one compound permanent magnet system located within the gap, the compound permanent magnet system including a first section magnetized in a first direction parallel to the width of the gap and a second section axially displaced from the first section magnetized in a direction opposite to the first direction.
  • the compressor includes at least one synchronous electric motor, referred to as the "compressor motor " , the system further comprising a voltage source, both the displacer motor and the compressor motor being operatively connected so as to be driven by the voltage source.
  • the compressor motor there is also provided at least one element with variable impedance connected between the voltage source and one of the displacer motor and the compressor motor for adjusting the relative phase between the compressor and the displacer.
  • FIG. 1 is a cross-sectional view of a displacer assembly, constructed and operative according to the teachings of the present invention, for use in a Stirling cycle system;
  • FIG. 2 is a side cross-sectional view through a synchronous twin reciprocating piston compressor apparatus, constructed and operative according to the teachings of the present invention, for use with the displacer assembly of Figure 1 to form a Stirling cycle system;
  • 1TG. 3 is a schematic side cross-sectional view showing the magnetic flux patterns during operation of the apparatus of Figure 2;
  • FIG. 4A is a schematic perspective view of a core of a stator assembly for use in the apparatus of Figure 2;
  • FIG. 4B is a side cross-sectional view through the stator core of Figure 4A;
  • FIG. 4C is an end view of the stator core of Figure 4 A;
  • FIG. 5A is a cut-away perspective view of a first alternative stator core structure produced from ferrite;
  • FIG. 5B is a cut-away perspective view of a second alternative stator core structure produced from ferrite
  • FIG. 6A is a schematic perspective view of a piston-magnet assembly for use in the apparatus of Figure 2, the assembly including a compound permanent magnet system;
  • FIG. 6B is a schematic perspective view of an alternative piston-magnet assembly for use in the apparatus of Figure 2;
  • FIG. 7 A is a schematic side cross-sectional view through the piston- magnet assembly of Figure 6 A;
  • FIG. 7B is a view similar to Figure 7A showing an alternative compound permanent magnet system structure;
  • FIG. 8 is a schematic perspective view of a magnetic compensation mechanism for use in the apparatus of Figure 2;
  • FIG. 9 is a side cross-sectional view through a variant form of the apparatus of Figure 2;
  • FIG. 10A is a side cross-sectional view through a form of stator core used in the apparatus of Figure 9;
  • FIG. 1 OB is a side cross-sectional view through an alternative form of stator core for use in the apparatus of Figure 9;
  • FIGS. 1 1 A and 1 IB are side cross-sectional views showing the magnetic llux patterns generated by the forms of stator shown in Figures 10A and 10B, respectively; and
  • FIG. 12 is a schematic representation of a Stirling cycle system including the displacer assembly of Figure 1 and the compressor apparatus of Figure 2.
  • the present invention is a Stirling cycle displacer assembly driven by a synchronous linear motor with a magnetic spring, and a Stirling cycle system including the same.
  • the principles and operation of Stirling cycle devices according to the present invention may be better understood with reference to the drawings and the accompanying description.
  • Figure 1 shows a displacer assembly, generally designated 100, constructed and operative according to the teachings of the present invention, for use in a Stirling cycle system.
  • Displacer assembly 100 may be used to advantage with any type of compressor to construct a Stirling cycle system.
  • a synchronous twin reciprocating piston compressor apparatus is used.
  • Such a compressor the subject of related co-pending U.S. Patent Application No. 08/599,206 filed February 9, 1996, issued on December 2, 1997, as U.S. Patent No. 5,693,991 and hereby incorporated in its entirety by reference, will be described below with reference to Figures 2- 1 1.
  • displacer assembly 100 includes a displacer 102 in the form of a hollow cylinder along which a regenerator 104 travels.
  • Regenerator 104 is constructed to function as a heat exchanger, by way of example shown here as a thin-walled cylinder 106 containing numerous metal screens 108 forming a cylindrical matrix.
  • motor 112 It is a particular feature of motor 112 that its construction is designed to provide a magnetic spring such that, when no power is supplied to the motor, displacer 102 returns to a predefined rest position.
  • this is to be understood to refer to the position of the movable component of the displacer, in this case, regenerator 104.
  • axis 114 is collinear with the axis of displacer 102, although a non-collinear mechanical link could alternatively be employed.
  • motor 112 includes at least one stator assembly 1 16 having a core which provides first and second pole pieces 118 defining therebetween a gap 120.
  • Pole pieces 118 are made from soft magnetic material and are deployed such that a dimension referred to as the "width" of gap 120, corresponding to the line of shortest distance between the two pole pieces, is oriented perpendicular to axis 114.
  • Stator assembly 1 16 also includes at least one coil 122 associated with the core so as to generate a magnetic field aligned primarily parallel to the width of gap 120.
  • Located within gap 120 is at least one compound permanent magnet system 124.
  • Compound permanent magnet system 124 includes a first section 126 magnetized in a first direction parallel to the width of gap 120 and a second section 128 axially displaced from first section 126 and magnetized in a direction opposite to the first direction.
  • First and second sections 126 and 128 may be directly adjacent, i.e., forming a butt-joint therebetween. Alternatively, they may be slightly axially spaced apart.
  • motor 112 functions as a non-contact magnetic spring, returning and retaining the displacer in a desired rest position.
  • This self- centering effect stems from the well defined lowest energy position of compound permanent magnet system 124 in which maximum magnetic flux closure occurs through the soft magnetic material of pole pieces 118.
  • mechanical spring elements with their accompanying problems of efficiency and reliability can be omitted altogether from the displacer assembly design.
  • motor 112 is preferably mounted in fixed relation to the outer cylinder of displacer 102 through a common housing 130. Housing 130 typically features a linear bearing and a dynamic seal around drive rod 110. Connection between displacer 102 and a compressor to construct a Stirling cycle system is achieved via a gas inlet pipe 132 and connection tube 134.
  • displacer assembly 100 can be used to advantage with any compressor design. Synchronization, amplitude control, and emulation of various mechanical damping effects can all be achieved by electronic control of a source of oscillating current and the associated circuitry. Preferably, synchronization between the compressor and displacer is ensured by using a common oscillatory source for both, phase adjustment being performed either by use of additional components with suitable impedances or by other digital or analogue methods.
  • displacer assembly 100 is used with a compressor driven by a motor of which the design shares similar properties to those of motor 112 described above. Various examples of such compressors will now be described.
  • FIG. 2 shows a compressor, generally designated 10, constructed and operative according to the teachings of the present invention.
  • compressor 10 includes a cylinder 12, two identical stator assemblies 14 fixed relative to cylinder 12 for producing a concentrated alternating radial magnetic field in regions 16, and a pair of piston-magnet assemblies 18.
  • Each piston-magnet assembly 18 includes a piston 20 slidable within part of cylinder 12 and a number of compound permanent magnet systems 22 located within regions 16.
  • stator assemblies 14 are excited by an alternating current, alternating axial forces are exerted on compound permanent magnet systems 22 thereby causing synchronous opposing reciprocation of pistons 20 within cylinder 12.
  • the reciprocation of pistons 20 within cylinder 12 gives rise to oscillating pressure at the center of cylinder 12.
  • axial refers to a direction or dimension which is parallel to the central axis of cylinder 12.
  • radial is used herein in the specification and claims to refer to a direction or dimension perpendicular to this axis.
  • the present invention is described herein as a single cylinder structure, it may readily be adapted to a multiple cylinder system.
  • a number of synchronous systems functioning in parallel may be connected at their outlets.
  • a number of cylinders may be combined into a single unit with a plurality of angularly-spaced inter-connected bores each receiving a pair of opposing pistons-magnet assemblies.
  • cylinder 12 has an internal bore which is ground to high precision for receiving pistons 20.
  • An outlet tube 24 is connected to the inner volume of cylinder 12 near its center.
  • an additional inlet tube and appropriately positioned valves may be added.
  • compressor 10 features a radially extending flange 13 integrally formed with cylinder 12 at the center of its length.
  • each stator assembly includes at least one coil 26 and a core made up of one or more pairs of stator packs 28 arranged symmetrically about the axis of cylinder 12.
  • Independent stator assemblies 14 are preferably provided for driving each piston-magnet assembly 18.
  • Each stator assembly 14 is attached to flange 13.
  • stator assembly 14 may extend along a major part of the length of cylinder 12 to provide regions 16 around both ends of cylinder 12, as will be illustrated below with reference to Figure 9. It is a particular feature of the present invention that stator assemblies 14 produce a substantially radial magnetic field pattern concentrated within regions 16.
  • stator packs 28 are generally shaped as substantially closed magnetic circuits which pass through coil 26. Regions 16 are defined by relatively narrow breaks in stator packs 28 formed between gap faces 30 and 31.
  • the magnetic flux patterns corresponding to the view of Figure 2 are shown in Figure 3.
  • stator packs 28 are arranged with hexagonal symmetry about the axis of cylinder 12, as shown in Figures 4A. 4B and 4C.
  • Stator packs 28 are preferably constructed from a plurality of laminations parallel to the magnetic flux direction, thereby minimizing the magnetic losses.
  • Gap faces 30 and 31 are shaped to match the shape of compound permanent magnet systems 22. Thus, they are typically curved to match a cylindrical magnet design which will be described below with reference to Figure 6A. Alternatively, parallel planar gap faces 30 and 31 may be used to match a polygon-structured compound permanent magnet system, as will be described below with reference to Figure 6B.
  • Coils 26 and stator packs 28 are constructed to produce magnetic fields of equal magnitude, up to given tolerances, in each region 16. Thus, where separate coils 26 are used to generate the fields at the two ends of cylinder 12, similar coils of equal numbers of Ampere-turns are used. Similarly, stator packs 28 are designed and positioned symmetrically relative to both to rotation about the axis of cylinder 12, and reflection in a plane perpendicular thereto. In practice, the symmetry of the magnetic fields produced is limited by the tolerances of the components used. Mechanisms for compensating for distortion of the magnetic fields will be discussed below.
  • stator assemblies 14 may be constructed from Ferrite in a manner known in the art.
  • Ferrite for stator assemblies 14 makes possible additional stator structures.
  • stators assemblies 14 may be constructed as a solid of revolution of any of the disclosed stator cross-sections, thereby generating magnetic fields within a region 16 with circular symmetry.
  • the ferrite core is typically made from two or more sections which are then fixed together.
  • Figure 5A shows an example in which a three-piece structure is used.
  • Figure 5B shows a simplified two-piece construction.
  • Piston-magnet assembly 18 includes piston 20 and compound permanent magnet systems 22 connected through a cap 32. Piston 20 is preferably machined to match the internal bore of cylinder
  • piston 20 with a clearance of at least a few ⁇ m (typically about 8-30 ⁇ m).
  • the material for piston 20 is chosen based on mechanical considerations alone, since the magnetic character of piston 20 is not important. Piston 20 is therefore typically made from a hardened low-friction material. Piston 20 may alternatively be constructed from a soft, light-weight material such as, for example, aluminum, and then coated with appropriate coatings, as is known in the art.
  • Compound permanent magnet system 22 is made up of a first section 34 magnetized with its direction of magnetization radial relative to the axis of cylinder 12, and a second section 36, adjacent to, and axially displaced from first section 34, magnetized with its direction of magnetization opposite to that of first section 34.
  • First and second sections 34 and 36 are generally produced separately and then attached by any suitable type of bonding.
  • first and second sections 34 and 36 are radially magnetized cylindrical magnets as shown in Figure 6A.
  • each section may be made up of a number of planar permanent magnets mounted together so as to form a regular polygon as shown in Figure 6B.
  • first and second sections 34 and 36 are closed structures symmetrical about their axis, thereby providing the structural rigidity required for precise alignment.
  • gap faces 30 and 31 of stator packs 28 are shaped to match the shape of compound permanent magnet system 22 with a clearance of about 0.1-1 mm between compound permanent magnet system 22 and each gap face 30 and 31.
  • Figure 7B shows an alternative construction for the piston-magnet assemblies of Figures 6A and 6B.
  • a layer 38 of magnetically conductive material integrally formed with cap 32, forms a core on which compound permanent magnet system 22 is constructed.
  • Layer 38 may also be integrally formed with piston 20.
  • First section 34 and second section 36 are each then formed by attachment of suitably magnetized permanent magnets on to the inner and outer faces of layer 38.
  • layer 38 integrally formed with cap 32 provides additional structural rigidity and help to ensure proper alignment of the magnets with piston 20.
  • Layer 38 is formed as a hollow tube of a cross-sectional shape matching the required shape of compound permanent magnet system 22.
  • the cross-section will be circular, and for the form shown in Figure 6B, it will be the corresponding polygon.
  • stator assembly 14 When compressor 10 is assembled, stator assembly 14 is mounted in fixed relation around cylinder 12 such that it provides a plurality of regions 16 arranged symmetrically near each end of cylinder 12. Piston-magnet assemblies 18 are the positioned at each end of cylinder 12 with pistons 20 inserted within the bore of cylinder 12 and compound permanent magnet systems 22 inserted within regions 16. Inner stops 42 attached to stator packs 28 limit the range of sliding motion of piston-magnet assemblies 18, thereby preventing collision of pistons 20. Compressor 10 generally also features a casing 44 which provides support and rigidity to the entire structure. Outer stops 45, attached to casing 44, prevent piston-magnet assemblies 18 from overshooting outward from their normal range of working positions. Stops 42 and 45 are preferably made of resilient material such as, for example, natural or synthetic rubber.
  • the clearance gaps between gap faces 30, 31 and compound permanent magnet systems 22 are significantly greater, and typically one or two orders of magnitude greater, than the clearance gaps between pistons 20 and the internal bore of cylinder 12. This feature ensures effective pumping operation while protecting the mechanically soft magnetic components of compressor 10 from unnecessary wear.
  • the clearance gaps between gap faces 30, 31 and compound permanent magnet systems 22 should not be increased beyond the extent required for protection from wear since the resultant widening of regions 16 would cause weakening of the magnetic field.
  • compressor 10 when coils 26 are excited by alternating current, alternating substantially radial magnetic fields are generated within regions 16.
  • the section 34 of compound permanent magnet system 22 which is magnetized in alignment with the field tries to align centrally in the field, and the section 36 which is magnetized in the opposing sense is repelled.
  • the net result of these forces is a purely axial force on each compound permanent magnet system 22 which is transferred through cap 32 to piston 20.
  • the forces are reversed, thereby forcing piston 20 in the opposite direction.
  • the alternating current supply causes compound permanent magnet systems 22, and hence piston 20, to reciprocate axially.
  • compressor 10 does not require the springs invariably featured in conventional linear compressors. Due to the opposing- poles structure of compound permanent magnet systems 22, piston-magnet assemblies 18 will naturally tend to a centered resting position in the absence of current in coils 26.
  • coils 26 are preferably provided with independent electrical connections with switchable polarity. This feature allows construction of piston-magnet assemblies 18 without requiring unique determination of the polarity of each magnet used. Then, before use of compressor 10, a polarity checking procedure is performed. The polarity checking procedure requires applying a non-alternating (D.C.) voltage across the coils and observing the direction of displacement of both piston-magnet assemblies. If both are drawn inwards towards cylinder 12, or alternatively, both move outwards away from the cylinder, then it is clear that the connection of the coils is correct for the polarity of the magnets. If, on the other hand, one piston-magnet assembly moves inwards and the other outwards, the polarity of one of coils 26 is reversed.
  • D.C. non-alternating
  • compressor 10 features a magnetic compensation mechanism for modifying the magnetic fields so as to minimize frictional power losses and vibration in compressor 10 during operation.
  • Figure 8 shows an example of a magnetic compensation mechanism, generally designated 46, for modifying the magnetic fields in regions 16.
  • Mechanism 16 includes a collar 48 formed with recesses 50 for engaging parts of stator assemblies 14 (as seen in Figure 4A) and threaded radial bores 52.
  • a number of inserts 54 made from soft magnetic material are formed as threaded pins which fit radial bores 52.
  • a material suitable for producing inserts 54 is the material commercially available under the tradename "Carpenter 49".
  • additional windings may be located around individual stator packs 28 and be supplied selectively with a
  • D.C. current A rheostat or other current control device is used to vary the current through the additional windings of one or more of stator packs 28. This has an effect analogous to adjustment of inserts 56 in magnetic compensation mechanism 46, and is used to balance radial forces in a manner similar to that described above.
  • FIG. 10 a variant form of a compressor, generally designated 56, constructed and operative according to the teachings of the present invention, will now be described.
  • Compressor 56 is generally similar to compressor 10, and equivalent elements are labeled similarly.
  • stator assemblies 14 are elongated so as to provide the required magnetic fields in regions 16 at both ends of cylinder 12.
  • Figures 10A and 10B show two possible forms for stator packs 28 in this embodiment.
  • Figures 1 1A and 1 IB show the magnetic flux patterns corresponding to the forms of Figures 10A and
  • compressor 56 A further difference between compressor 56 and compressor 10 is the provision in compressor 56 of a spring 58.
  • piston- magnet assemblies 18 are self-centering without the need for springs.
  • springs 58 it is preferable to include springs 58, as shown.
  • Springs 58 provide additional biasing of piston-magnet assemblies 18 towards their central position, and increase the stability of the system in sub- resonance conditions.
  • a linear bearing 40 not present in compressor 10, is included in compressor 56. Linear bearing 40 helps to maintain the highly precise alignment required between piston-magnet assemblies 18 and cylinder 12. Linear bearing 40 may be attached directly to cylinder 12, or fixed in alignment with it through attachment to stator packs 28 or to another part of compressor 10 which is fixed relative to cylinder 12.
  • control system 60 includes an AC voltage source 62 and a phase-altering device 64.
  • One element, in this case compressor 10 is connected directly to the voltage source 62 while the other, in this case displacer assembly 100, is connected via phase-altering device 64. Since the two outputs provided by control system 60 are synchronous but out of phase, the required synchronicity of the compressor motor and displacer motor is ensured.
  • phase-altering device 64 may perform phase adjustment either by use of additional components with suitable impedances or by other digital or analogue methods.
  • various elements may be included to provide the equivalent of viscous friction retardation or other mechanical effects.
  • voltage source 62 and phase-altering device 64 may be implemented as separate units, referred to collectively as the control system, or may be combined into a single control unit.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Reciprocating, Oscillating Or Vibrating Motors (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
  • Linear Motors (AREA)

Abstract

L'invention concerne un ensemble de piston déplaceur pour un système à cycle de Stirling comprenant un piston déplaceur (102) et un moteur électrique (112) linéaire synchrone, reliés de manière à entraîner le dit piston déplaceur (102). Le moteur électrique (112) comprend au moins un ensemble de stator (116) pourvu d'une première et d'une seconde pièces polaires (118) magnétiques douces, définissant entre elles un entrefer (120). La largeur de l'entrefer (120) est orientée perpendiculairement à un axe de déplacement du moteur, et l'ensemble de stator est construit de manière à produire un champ magnétique aligné dans une direction essentiellement parallèle à la largeur de l'entrefer (120). Le moteur (112) comprend également au moins un système d'aimant (124) permanent compound, ayant une première section (128) axialement décalée par rapport à la première section magnétisée, dans une direction opposée à la première direction.
PCT/US1997/021666 1997-12-01 1997-12-01 Ensemble de piston deplaceur pour un systeme a cycle stirling WO1999028685A1 (fr)

Priority Applications (6)

Application Number Priority Date Filing Date Title
EP97949629A EP1042637A4 (fr) 1997-12-01 1997-12-01 Ensemble de piston deplaceur pour un systeme a cycle stirling
JP2000523504A JP2001525530A (ja) 1997-12-01 1997-12-01 スターリングサイクル・システム用ディスプレーサ組立て
KR10-2000-7005843A KR100516236B1 (ko) 1997-12-01 1997-12-01 스털링 사이클 시스템 및 그를 위한 디스플레이서 조립체
PCT/US1997/021666 WO1999028685A1 (fr) 1997-12-01 1997-12-01 Ensemble de piston deplaceur pour un systeme a cycle stirling
AU35876/99A AU3587699A (en) 1997-12-01 1997-12-01 Displacer assembly for stirling cycle system
TW087109470A TW429299B (en) 1997-12-01 1998-06-15 Displacer assembly for stirling cycle system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1997/021666 WO1999028685A1 (fr) 1997-12-01 1997-12-01 Ensemble de piston deplaceur pour un systeme a cycle stirling

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WO1999028685A1 true WO1999028685A1 (fr) 1999-06-10

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PCT/US1997/021666 WO1999028685A1 (fr) 1997-12-01 1997-12-01 Ensemble de piston deplaceur pour un systeme a cycle stirling

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EP (1) EP1042637A4 (fr)
JP (1) JP2001525530A (fr)
KR (1) KR100516236B1 (fr)
AU (1) AU3587699A (fr)
TW (1) TW429299B (fr)
WO (1) WO1999028685A1 (fr)

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US7937939B2 (en) 2004-01-16 2011-05-10 Mark Christopher Benson Bicycle thermodynamic engine
EP2594792A1 (fr) * 2010-08-05 2013-05-22 LG Electronics Inc. Compresseur linéaire
WO2015017830A1 (fr) * 2013-08-02 2015-02-05 Chart Inc. Refroidisseur cryogénique à piston alternatif magnétique

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JP4696551B2 (ja) * 2004-12-16 2011-06-08 ダイキン工業株式会社 圧縮機
DE102013218068A1 (de) * 2012-12-06 2014-06-12 Robert Bosch Gmbh Linearantrieb
TWI558965B (zh) * 2015-02-13 2016-11-21 國立成功大學 具相位差調整功能的史特靈循環裝置及其相位差調整方法

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US4534176A (en) * 1984-03-23 1985-08-13 The United States Of America As Represented By The Secretary Of The Army Linear resonance cryogenic cooler
US4610143A (en) * 1984-12-18 1986-09-09 North American Philips Corporation Long life vibration canceller having a gas spring
US4862695A (en) 1986-11-05 1989-09-05 Ice Cryogenic Engineering Ltd. Split sterling cryogenic cooler
US5693991A (en) 1996-02-09 1997-12-02 Medis El Ltd. Synchronous twin reciprocating piston apparatus

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7937939B2 (en) 2004-01-16 2011-05-10 Mark Christopher Benson Bicycle thermodynamic engine
EP2594792A1 (fr) * 2010-08-05 2013-05-22 LG Electronics Inc. Compresseur linéaire
EP2594792A4 (fr) * 2010-08-05 2014-09-17 Lg Electronics Inc Compresseur linéaire
US9261088B2 (en) 2010-08-05 2016-02-16 Lg Electronics Inc. Linear compressor
WO2015017830A1 (fr) * 2013-08-02 2015-02-05 Chart Inc. Refroidisseur cryogénique à piston alternatif magnétique
CN105556813A (zh) * 2013-08-02 2016-05-04 查特股份有限公司 具有磁性往复运动活塞的低温制冷机
GB2533240A (en) * 2013-08-02 2016-06-15 Chart Inc Cryocooler with magnetic reciprocating piston
US10527320B2 (en) 2013-08-02 2020-01-07 Chart Inc. Cryocooler with magnetic reciprocating piston
GB2533240B (en) * 2013-08-02 2020-03-11 Chart Inc Cryocooler with magnetic reciprocating piston

Also Published As

Publication number Publication date
KR20010032589A (ko) 2001-04-25
EP1042637A1 (fr) 2000-10-11
KR100516236B1 (ko) 2005-09-20
TW429299B (en) 2001-04-11
AU3587699A (en) 1999-06-16
JP2001525530A (ja) 2001-12-11
EP1042637A4 (fr) 2004-03-31

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