JP2009047152A - Free piston type stirling cycle engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an efficient Stirling cycle engine increasing thermal efficiency by reducing thermal resistance between working gas and thermal medium, and reducing electric resistance of magnet coils of a drive device or a power generation device. <P>SOLUTION: The Stirling cycle engine includes a plurality of linear heat absorbing pipe 2 exchanging heat by making working gas pass through the same, a heat absorbing body comprising a heat absorbing pipe retaining member upper 3 and a heat absorbing pipe retaining member lower 10 at both ends of the heat absorbing pipes 2, a plurality of linear heat discharging pipes 17 exchanging heat by making the working gas pass through the same, and a heat discharging body comprising a heat discharging pipe retaining member upper 14 and a heat discharging pipe retaining member lower 19 retaining the heat discharging pipes 17 at both ends. A permanent magnet for the drive device or the power generation device is arranged at a piston inner circumference part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a structure of a heat exchanger for heating or cooling a working gas of a free piston type Stirling cycle engine.

Conventionally, for example, a Stirling cycle engine disclosed in Patent Document 1 is known. In this Stirling cycle engine, a piston and a displacer are slidably inserted into a cylinder provided in a casing, and when operating as a Stirling cooler, the piston is reciprocated by a drive mechanism. was there. And when the piston is driven by the drive mechanism and moves in the cylinder in a direction approaching the displacer, the gas (working gas) in the compression chamber formed between the piston and the displacer is compressed, The displacer has a predetermined phase difference with respect to the piston by passing through the heat dissipating fin, the regenerator, and the heat absorbing fin and reaching the expansion chamber formed between the tip of the displacer and the tip of the casing. Pushed down. On the other hand, when the piston moves away from the displacer, the inside of the compression chamber becomes negative pressure, and the gas (working gas) in the expansion chamber passes through the heat absorption fins, the regenerator, and the heat radiation fins to compress the compression. By returning to the chamber, the displacer is pushed up with a predetermined phase difference with respect to the piston. By performing a reversible cycle consisting of two isothermal changes and isovolume changes during such a process, the vicinity of the expansion chamber becomes low temperature, while the vicinity of the compression chamber becomes high temperature. (For example, patent document 1).
In order to operate the Stirling cycle engine as an engine, heat is applied to the internal gas (working gas) through the heat absorption fin, and the gas (working gas) in the expansion chamber becomes hot and expands, and the heat absorption fin connected to the expansion chamber. The space of the compression chamber is expanded through the regenerator and the heat radiation fin, and the piston is moved away from the displacer. Then, the displacer is pushed up with a predetermined phase difference from the piston in the direction of the expansion chamber due to the pressure difference between the compression chamber side and the opposite side of the piston, so that the gas (working gas) in the expansion chamber further moves to the compression chamber and is cooled by the cooling fins. It cools and shrinks. Then, the piston moves in the direction approaching the displacer, and the displacer moves in the direction approaching the piston with a predetermined phase difference from the piston due to the pressure difference between both ends of the piston. It moves to the expansion chamber through the regenerator and the endothermic fin, and the gas (working gas) is again heated and expanded. By repeating this operation, the piston and the displacer reciprocate, and the permanent magnet coupled to the piston reciprocates to generate electric power by a power generation device including an electromagnetic core, an electromagnetic coil, and the like.

However, since the heat absorption fins and the heat radiation fins are provided inside the casing, the heat transfer from the outside to the working gas and the discharge of the internal heat to the outside are performed through the casing. In addition, the heat resistance due to contact between the casing and the fins inside the casing is not efficient. As a result, the efficiency of the Stirling cycle engine was low.
For example, Patent Document 2 discloses a method for improving the heat transfer between the outside of the Stirling cycle engine and the working gas inside the Stirling cycle engine, but the heat transfer and transfer is performed through the outer shell container (casing) of the Stirling cycle engine. Therefore, there is a thermal resistance in the thickness direction of the casing and a thermal resistance between the casing and the heat exchanger, and the improvement of the heat transfer efficiency is insufficient.

Further, the casing which is a pressure vessel has a limited surface area, and it is difficult to provide a sufficient surface area to be suitable for heat transfer. For example, as disclosed in Patent Document 3, an outer shell container (casing) is used. A means for increasing the efficiency of heat transfer by adding a heat transfer member to the outside is disclosed.
However, even in this case, the thermal resistance between the external heat medium and the internal working gas is (heat resistance between the heat medium and the external heat transfer member) + (heat resistance of the heat transfer member) + (heat Thermal resistance between transmission member and casing) + (thermal resistance of casing) + (thermal resistance between casing and internal fin) + (thermal resistance of fin) + (thermal resistance between fin and working gas), There are many factors of thermal resistance, and thermal resistance cannot be made sufficiently small.

  Further, as disclosed in Patent Document 4, a method is disclosed in which a large number of U-shaped tubes through which working gas passes are connected to the expansion space head portion to improve heat exchange efficiency. U-shaped pipes need to be joined by welding or brazing, but their shapes are likely to be non-uniform and complex compared to straight pipes, and it is necessary to project them further, making the joining process difficult. Cost is high. Further, this document does not mention improvement of the thermal efficiency of the exhaust heat portion. Furthermore, when the number of U-shaped tubes is increased in order to improve the thermal efficiency, there is a drawback that the volume of the expansion chamber of the Stirling cycle engine increases and the efficiency is lowered.

  Furthermore, as disclosed in Patent Document 1, the electromagnetic coil of the conventional piston electromagnetic drive device is arranged in a portion larger than the outer diameter of the piston. As a result, the diameter of the electromagnetic coil is increased, which increases the electrical resistance of the conducting wire, which reduces the efficiency of the Stirling cycle engine.

Japanese Patent No. 3887823 (paragraphs 0002 and 0009) Patent Application Publication Pub. No. : US2005 / 0268606A1 (paragraphs 0010, 0019) Special table 2004-506837 JP-A-5-172003

Any of the above-mentioned methods conventionally proposed for increasing the thermal efficiency of the Stirling cycle engine has improved the thermal efficiency, but has been unsatisfactory.
Therefore, the present invention is easy to manufacture and is low in cost and increases thermal efficiency by reducing the thermal resistance between the working gas inside the Stirling cycle engine and a heat medium such as air or water outside the Stirling cycle engine, and further increases the electromagnetic coil. The purpose is to increase the efficiency of the Stirling cycle engine by reducing the electrical resistance.

  According to a first aspect of the present invention, there is provided a displacer that is slidably inserted into a tip side of a cylindrical cylinder, a piston that is slidably inserted into a start side of the cylinder, and the piston and the displacer. A compression chamber formed therebetween, a regenerator provided between the endothermic body and the exhaust heat body, and the endothermic body and the exhaust heat body on the outer periphery of the cylinder; The regenerator, a path leading to the compression chamber through the exhaust heat body, a drive device arranged on the starting end side of the cylinder to reciprocate the piston, or a power generation device that generates power by reciprocating the piston. In the Stirling cycle engine, the heat absorber or the exhaust heat body, or both the heat absorber and the exhaust heat body are provided with holding members that hold the plurality of tubes at both ends of a plurality of linear tubes through which the working gas passes. Outside the serial plurality of tubes is obtained by the arrangement through a heating medium such as air or water.

  In addition to the first aspect, the second aspect of the invention is the same as that of the first aspect, wherein the outer diameter of the permanent magnet of the power generation device that generates electric power by reciprocating the piston drive device or the piston is made smaller than the outer diameter of the piston. By disposing the electromagnetic coil on the inner side, the electric resistance of the electromagnetic coil is reduced and the electrical loss is also reduced.

  According to the first aspect of the present invention, by directly heating or cooling the working gas passed through the plurality of straight pipes with a heat medium such as air or water, the thermal resistance between the working gas and the heat medium is Only the sum of the thermal resistance between the heat medium and the pipe outer wall surface, the thermal resistance in the thickness direction of the pipe, and the thermal resistance between the pipe inner wall surface and the working gas can be reduced. Therefore, the temperature difference between the heat medium and the working gas is reduced, and the thermal efficiency can be increased. In addition, the plurality of tubes are straight, and there are members that hold both ends of the plurality of tubes. A heat absorption body or a heat exhaust that includes the plurality of straight tubes and members that hold both ends of the tubes is used. Since it is possible to perform welding and brazing work by itself, manufacturing is easy and cost can be reduced. Furthermore, the number and diameter of the plurality of straight tubes through which the working gas passes can be designed optimally for the efficiency of the Stirling cycle engine. That is, there is a high degree of freedom in designing the tube diameter and the number of tubes appropriately in consideration of the contact area with the heat medium and the flow resistance of the working gas, and the design for increasing the efficiency becomes easy. According to the second aspect of the present invention, the permanent magnet is made smaller than the outer diameter of the piston, and the electromagnetic coil is arranged inside the permanent magnet, whereby the electric resistance can be reduced, and the Stirling cycle engine The efficiency is further improved.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In FIG. 1, reference numeral 8 denotes a metal cylinder in which a displacer 9 is inserted inside the tip and a piston 23 is slidably inserted in the starting end. The outer peripheral portion of the cylinder 8 has a plurality of heat absorption tubes 2 through which the working gas passes, a heat absorption tube holding member upper 3 and a heat absorption tube holding member lower 10 and a plurality of heat exhaust tubes 17 through which the working gas passes and a heat exhaust tube holding member. A cylindrical fixing member 7 to which a heat exhaust body comprising an upper part 14 and a heat exhaust pipe holding member lower part 19 and a regenerator 13 provided between the heat absorber and the exhaust heat body is attached is press-fitted or bonded to the cylinder 8. It is fixed by mounting. The inner peripheral portions of the upper endothermic tube holding member 3, the lower endothermic tube holding member 10, the upper exhaust heat tube holding member 14, and the lower exhaust heat tube holding member 19 are joined and sealed to the fixing member 7 by welding or bonding. .
Note that the upper ends of the plurality of heat absorbing tubes 2 are joined and sealed to the heat absorbing tube holding member 3 by brazing or bonding. Similarly, the lower ends of the plurality of heat absorption tubes 2 are sealed by joining to the lower heat absorption tube holding member 10 by brazing or bonding. Similarly, the upper ends of the plurality of heat exhaust pipes 17 are joined and sealed to the heat exhaust pipe holding member upper part 14 and the lower ends thereof to the heat exhaust pipe holding member lower part 19 by brazing or bonding, respectively.

  The outer peripheral portion of the upper endothermic tube holding member upper 3 is joined and sealed to the top casing 1 by welding, bonding, or the like, and the upper end 12 of the casing is disposed on the outer peripheral portion of the regenerator 13, and the outer peripheral portion is the endothermic portion. The pipe holding member lower 10 and the exhaust heat pipe holding member upper 14 are joined and sealed by welding, bonding or the like, respectively. Further, a lower middle casing 20 is joined and sealed to the lower heat pipe holding member lower 19 by welding or adhesion, and a lower middle casing holding member 30 is welded to the lower middle casing 20. The lower 20 is fixed to the starting end portion of the cylinder 8 with a bolt or the like through the lower middle holding member 22 in the casing. Further, the lower middle 20 of the casing is joined and sealed to the bottom casing 21 by welding or the like.

  At the lower end portion of the cylinder 8, a stator attachment large 27 for fixing an electromagnetic stator 26 provided with an electromagnetic coil 29 for a driving device or a power generation device together with a stator attachment small 28 is attached by a bolt or the like. Yes. And this stator attachment tool size 27 is fixed to the lower end of the cylinder 8 with a bolt or the like, and is arranged on the outer periphery of the electromagnetic stator 26 with a slight magnetic gap from the electromagnetic stator 26. A cylindrical permanent magnet 25 is attached to the inside of the magnetic conducting part 24 attached to the inside of the piston 23 by adhesion or the like. One end of a rod 31 for controlling the operation of the displacer 9 is connected to the starting end side of the displacer 9, and a leaf spring 30 is connected to the other end of the rod 31. Further, the leaf spring 30 is disposed at the lower end portion of the cylinder 8. The rod 31 extends through the piston 23 and is slidable with the piston 23. In this embodiment, the permanent magnet 25 is disposed inside the piston 23. However, as shown in Reference 1, a permanent magnet for a driving device or a power generator is disposed outside the piston. It may be arranged. Moreover, although the permanent magnet 25 is cylindrical, it may be cylindrical by combining arc-shaped permanent magnets, even if it is not an integral structure. Although FIG. 1 shows a structure in which the magnetic conducting portion 24 reciprocates together with the permanent magnet 25, it is obvious that the magnetic conducting portion 24 may be separated from the piston 23 and fixed to the cylinder 8.

Next, the endothermic part will be described. A sealing tool 5 in which a plurality of connecting tools 6 for taking in or discharging a heat medium such as air, water or carbon dioxide gas is joined to the top casing 1 and the lower endothermic tube holding member 10 via the sealing materials 4 and 4. A space that surrounds the plurality of heat absorption tubes 2 is formed by being fastened to the air, and a heating medium such as air, water, or carbon dioxide gas is passed through the space, and the working gas that passes through the plurality of heat absorption tubes 2 is directly heated. . The sealing member 5 may be sealed by omitting the sealing material 4 and directly joining the top casing 1 and the lower endothermic tube holding member 10 by welding or the like.
Similarly, the exhaust heat portion will be described. A sealing tool 16 joined with a plurality of connecting tools 15 for taking in and out the heat medium is fastened and fixed to the upper middle 12 of the casing and the lower middle 20 of the casing via the sealing members 18, 18, thereby connecting the plurality of exhaust heat pipes 17. A surrounding space is formed. The heat medium is passed through this space, and the working gas passing through the exhaust heat pipe 17 is directly cooled. In addition, 11 is made of a breathable material made of metal or plastic fibers, etc., disposed between the heat absorption tube 2 and the regenerator 13 and between the exhaust heat tube 17 and the regenerator. The flow of the working gas is controlled to improve the efficiency of the Stirling cycle engine, but it is not necessary. In the above configuration, the casing, which is the outer shell of the Stirling cycle engine, is divided into four parts other than the heat absorber and the exhaust heat body that are part of the pressure vessel, so that the heat absorber, the regenerator, and the heat absorber can be easily incorporated. I have to. However, the mechanical strength is sufficiently maintained by the fixing member 7.

  FIG. 2 shows an embodiment in which a conventional fin structure is adopted as an endothermic body. Reference numeral 51 denotes an endothermic fin 52 made of a good thermal conductor such as copper on the casing and fixed by brazing or press fitting. ing. 3 is a cross-sectional view taken along line AA shown in FIG. 2, and heat from the outside of the Stirling cycle engine passes through the casing 51 and reaches the outer peripheral end of the heat-absorbing fin 52 and is transmitted to the entire fin. The working gas that passes through the space surrounded by the upper 51 and the endothermic fin 52 and the space surrounded by the endothermic fin 52 and the fixed body 7 are heated. Since heat is transmitted through the casing 51, the thermal efficiency of this portion is the same as that of the prior art, but the structure is simple and the cost can be reduced. By using a configuration combined with a good waste heat generator of the present invention, a Stirling cycle engine that balances cost and efficiency can be obtained. The casing upper 51 and the exhaust heat pipe holding member upper 14 are joined and sealed by welding or the like.

  FIG. 4 is a view showing another example of the embodiment 1 shown in FIG. 1, and the heat absorption tubes are made by increasing the axial lengths of the inner diameter portions of the lower endothermic tube holding member 10 and the lower exhaust heat tube holding member 19 in FIG. As the holding member lower 53 and the exhaust heat pipe holding member lower 54, the fixing member 7 in FIG. 1 is omitted and used by joining and sealing the upper heat absorption tube holding member 3 and the exhaust heat pipe holding member upper 14 by welding or brazing, respectively. The material is reduced. Of course, the inner diameter portion of the upper endothermic tube holding member 3 in FIG. 1 may be elongated in the axial direction and joined to the lower endothermic tube holding member 10 in FIG. 1 by welding, brazing, or the like. 1 may be elongated in the axial direction and joined to the lower heat exhaust pipe holding member 19 in FIG. 1 by welding, brazing, or the like for sealing.

FIG. 5 is a view showing a modification of the cylinder 8 in FIG. The cylinder 8 in FIG. 1 is usually made of metal such as aluminum die-casting. What is the temperature of the expansion chamber between the tip of the displacer 9 and the top casing 1 and the temperature of the compression chamber between the displacer and the piston? The larger one is desirable, that is, it is desirable that the member straddling both chambers has a larger heat transfer resistance.
In order to increase the heat transfer resistance, the cylinder 8 is preferably made of a material having a large heat transfer resistance, such as plastic or a thin stainless steel plate, in a portion extending between the two chambers. 5 shows an example in which the distal end portion of the cylinder 8 in FIG. 1 is separated from the cylinder 8 to form a plastic stuffer 59, and the proximal end portion of the cylinder 8 in FIG. 1 is shortened to the cylinder 58. FIG. 5 shows an example in which the stuffer 59 is a stuffer 60 made of a thin stainless steel plate. As a result, the heat transfer resistance between the expansion chamber and the compression chamber is increased, and the thermal efficiency can be improved. In FIG. 5, the fixing member 7 is fixed to the cylinder 58 by press-fitting or bonding, and the stuffer 59 is held by the fixing member 7.

It is a front sectional view of a Stirling cycle engine showing one example of the present invention. It is sectional drawing of the principal part which shows the other Example of this invention. FIG. 3 is a sectional view taken along line AA shown in FIG. 2. It is sectional drawing of the principal part which shows the structure of the other example of the heat sink in FIG. 1, and a waste heat body. It is sectional drawing which shows the other example of the cylinder 8 in FIG. It is sectional drawing which shows the further another example of the cylinder 8 in FIG.

Explanation of symbols

1 Top casing 2 Endothermic tube 3rd class heat tube holding member upper 4, 18 sealing material 5, 16 sealing member 6, 15 connector 7 fixing member 8, 58 cylinder 9 displacer 10, 53 endothermic tube holding member lower 11 buffer material 12 middle casing 13 upper regenerator 14 exhaust heat pipe holding member upper 17 heat exhaust pipe holding member 19, 54 exhaust heat pipe holding member lower 20 casing middle lower 21 bottom casing 23 piston 24 magnetism part 25 permanent magnet 26 electromagnetic stator 27 stator fixture large 28 Stator fixture Small 29 Electromagnetic coil 30 Leaf spring 31 Rod 51 Casing 52 Heat absorption fins 59, 60 Stuffer

Claims (5)

  A displacer inserted slidably inside the tip side of a cylindrical cylinder, a piston slidably inserted inside the start side of the cylinder, and a compression formed between the piston and the displacer A regenerator provided between the heat absorber and the heat sink disposed in the outer periphery of the cylinder, a heat absorber that absorbs heat from the working gas, a heat exhaust that discharges the heat of the working gas, and the heat sink. A path from the internal tip of the cylinder to the compression chamber through the heat absorber, the regenerator, the exhaust heat body, and a drive device disposed on the start side of the cylinder to reciprocate the piston, or a piston A power generation device that generates electric power by reciprocation, wherein the heat absorber, the exhaust heat body, or both of the heat absorber and the exhaust heat body include a plurality of linear tubes through which a working gas passes, and a plurality of the tubes Both Stirling cycle engine, characterized in that has a structure in which a holding member for holding the plurality of tubes.   The Stirling cycle engine according to claim 1, wherein an outer diameter of the permanent magnet of the driving device or the power generation device is smaller than an outer diameter of the piston.   A driving device for reciprocating the piston on the inner peripheral portion of the piston or a magnetic conducting portion of a power generating device for generating electric power by reciprocating the piston and a permanent magnet are attached, and an electromagnetic core of the driving device or the power generating device is located inside the piston. The Stirling cycle engine according to claim 1, wherein an electromagnetic coil is disposed. 2. The Stirling cycle engine according to claim 1, wherein a cylindrical fixing member for fixing the heat absorbing body or the exhaust heat body or both the heat absorbing body and the exhaust heat body is attached to the cylinder. 2. The Stirling cycle engine according to claim 1, wherein a stuffer made of a material having a larger heat transfer resistance than the cylinder is arranged inside the cylindrical fixing member.

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