JP3856670B2 - Stirling refrigeration engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a Stirling refrigerating engine.
[0002]
[Prior art]
FIG. 11 is a cross-sectional view of a conventional Stirling refrigerating engine. As shown in FIG. 11, in a Stirling refrigerating engine, a displacer 103 and a piston 102 are disposed in a cylinder 101 that forms a cylindrical space inside. A compression space 108 is provided between the displacer 103 and the piston 102, and an expansion space 109 is provided in contact with the end of the displacer 103 on the side opposite to the piston. A flow path is formed between the compression space 108 and the expansion space 109 so that the working gas flows through the regenerator 105 disposed on the outer periphery of the cylinder 101. The regenerator 105 is an essential element in the Stirling refrigerating engine in order to thermally isolate the compression space 108 and the expansion space 109.
[0003]
The working gas is confined in the working space whose main space is the expansion space 109, the compression space 108, and the flow passage. The working space is filled with a working gas such as helium, and the piston 102 is caused to make a periodic motion that reciprocates in the axial direction of the cylinder 101 by an external power of a linear motor (not shown), for example.
[0004]
The reciprocating motion of the piston 102 causes a periodic pressure change in the working gas enclosed in the compression space 108. First, the working gas is guided to the expansion space 109 through the regenerator 105 due to the pulsation of the back pressure that is increased accompanying the compression in the compression space. During this working gas movement, a periodic reciprocating motion occurs along the axial direction in the displacer 103 due to a change in the working gas movement amount. This reciprocating motion of the displacer 103 has the same period as the piston, and maintains a predetermined phase difference from the reciprocating motion of the piston.
[0005]
The end of the displacer on the piston side is continuous with the thin displacer rod 104. The displacer rod 104 passes through the shaft hole of the piston, and is connected to the other end of a spring 106 having one end fixed to the casing. The Stirling refrigerating engine having such a structure is called a free piston type Stirling refrigerating engine. Here, although a free piston type Stirling refrigerating engine will be described, the present invention is not intended only for a free piston type refrigerating engine.
[0006]
When the displacer 103 and the piston 102 reciprocate with an appropriate phase difference, the working gas enclosed in the working space in the cylinder constitutes a known thermodynamic cycle known as a reverse Stirling cycle. In this reverse Stirling cycle, cold heat is generated in the expansion space 109 and high heat is generated in the compression space 108. Next, the principle will be described.
[0007]
The working gas in the compression space 108 compressed by the piston 102 passes through the cylinder vent 101a and passes from the gas passage end space 112 connected to the vent to the high temperature side heat exchanger 110a, the regenerator 105, and the low temperature. It moves to the expansion space 109 via the side heat exchanger 110b. During this movement, the working gas is pre-cooled, receiving the cold that the regenerator 105 has stored half a cycle ago. The working gas releases heat generated in the compression space 108 from the radiator 111 to the outside through the high temperature side heat exchanger 110a. The high temperature side heat exchanger 110a and the heat radiator 111 are integrated to take heat from the working gas and radiate the heat to the outside. The regenerator 105 has an action of thermally isolating the compression space 108 and the expansion space 109 and is an essential element in a Stirling refrigerating engine.
[0008]
When most of the working gas flows into the expansion space, expansion starts so as to push the displacer 103 toward the piston by the pressure increase in the expansion space 109. And if it expands to some extent, the displacer 103 is pushed away from the piston by the return force of the piston 102. At this time, the pressure in the expansion space is reduced, and the working gas in the expansion space 109 is transferred from the low-temperature side heat exchanger 110b to the regenerator 105, the high-temperature side heat exchanger 110a, and the gas with the pressure reduced. It passes through the passage end space 112 and moves to the compression space 108 again. At this time, heat is taken from the outside by the heat absorber 116 through the low temperature side heat exchanger 110b. The low-temperature side heat exchanger 110b and the heat absorber 116 are integrated to give heat to the working gas and take heat away from the outside.
[0009]
As a result, the external air facing the heat absorber 116 is cooled. In this way, when most of the working gas returns to the compression space 108, the next cycle starts again under the compression operation of the piston 102. By repeating such a series of cycles continuously, it is possible to take out the cryogenic cold around the heat absorber 116. Conversely, the heat dissipation action can be used around the radiator 111.
[0010]
[Problems to be solved by the invention]
In the Stirling refrigeration engine, performance such as thermal efficiency is improved by reducing the volume of the gas passage end space 112 surrounded by the flange portion 101b of the cylinder 101, the casing 113, and the high temperature side heat exchanger 110a. That is, this gas passage end space is a space that should be called a dead space when the heat medium is circulated by repetition of compression and expansion, and the working gas is circulated efficiently by reducing the volume of this portion. To do. However, in the conventional Stirling refrigerating engine, the capacity of the gas passage end space 112 is reduced by reducing the distance between the flange portion 101b of the cylinder 101 and the high temperature side heat exchanger 110a. However, since it is necessary to secure the opening area of the vent 101a, the volume of the gas passage end space 112 cannot be made sufficiently small.
[0011]
When the cross section of the gas passage end space 112 in the vicinity of the flange portion 101b of the cylinder 101 is a plane orthogonal to the central axis 107, the cross-sectional shape cut by the plane including the central axis is a rectangular cylindrical shape. Become. For this reason, a flow loss has occurred in the flow of the working gas in the gas passage end space 112. Also, as shown in FIGS. 12 and 13, if the cross-sectional shape of the cut surface including the central axis of the gas passage end space 112 is made trapezoidal or fan-shaped so as to reduce the flow loss of the working gas, the machining process is performed. There was a complicated problem. That is, when the shape of the flange portion 101b of the cylinder 101 is processed into a conical shape or a dome shape so as to have the trapezoidal or fan-shaped cross-sectional shape described above, the processing method of the flange portion 101b and the vent 101a becomes complicated. There was a problem that caused an increase in cost. Note that if the volume of the gas passage end space continuous to the expansion space 109 is large, the thermal efficiency is lowered. However, in the case of the gas passage end space continuous with the expansion space, it is the end portion of the cylinder. Therefore, in order to reduce the volume and reduce the flow loss, the cross-sectional shape is trapezoidal or fan-shaped. There is no problem. That is, the target shape can be obtained by simple processing.
[0012]
It is also conceivable to reduce the gas passage end space 112 so that the high temperature side heat exchanger 110a faces the vent hole 101a. However, in this arrangement, it is necessary to change the direction of gas flow in the high temperature side heat exchanger. A heat exchanger that reduces the flow loss and changes the direction of the flow becomes very expensive and practically impossible.
[0013]
Further, the Stirling refrigeration engine can improve performance by reducing the gap between the cylinder 101 and the piston 102 or the gap between the cylinder 101 and the displacer 103. For this reason, the material of the cylinder 101 is made of a metal that is easily processed. For this reason, the heat generated in the compression space may be radiated to the inside of the Stirling refrigerating engine through the flange portion 101b of the cylinder 101. There was a situation in which the heat dissipation efficiency of the radiator 111 was lowered and the efficiency was lowered due to the heat generated by the motor.
[0014]
An object of this invention is to provide the Stirling refrigerating engine which implement | achieved the efficiency improvement cheaply and easily, without performing a complicated process.
[0015]
[Means for Solving the Problems]
The Stirling refrigerating engine of the present invention has a cylinder, a reciprocating displacer in the cylinder, and a piston driven by driving means, an expansion space between the displacer and the cylinder end, and the displacer and piston. The Stirling refrigerating engine further includes a regenerator that thermally separates the compression space and the expansion space in a gas passage outside the cylinder that has a compression space between them and communicates the compression space and the expansion space. This Stirling refrigeration engine is located outside the cylinder and communicates between the compression space and the expansion space. In the gas passage end space connected to the vent hole opened in the cylinder that opens in the compression space, the gas passage In order not to block the flow of the gas, the packing for reducing the volume of the gas passage end space is fixed in contact with the cylinder, and the packing is formed of a material having lower thermal conductivity than the cylinder. ).
[0016]
With this configuration, the filling material only needs to be formed of a member different from the cylinder or the like, so that the shape of the cylinder or the like need not be complicated, and the conventional cylinder shape can be used as it is. For this reason, the processing cost of the cylinder, which causes a large increase in cost, does not increase only by increasing the packing. As a result, the volume of the gas passage end space that continues to the compression space, which should be called a dead space when the working gas is circulated by compression and expansion, can be easily reduced. This gas passage end space may be referred to as a plenum space. Since the packing does not block the gas flow and is arranged so as to ensure the flow, the heat efficiency of the Stirling refrigerating engine can be improved as the dead space is reduced.
Also, the heat conduction is reduced by the ring by making the packing, for example the ring, of a material having a lower thermal conductivity than the cylinder. For this reason, the amount of heat radiated to the inside of the Stirling refrigerating engine through the cylinder can be reduced. Such a heat leak reduces the thermal efficiency of the radiator and reduces the efficiency of the linear motor by heating the linear motor etc. that drives the piston. In addition, the efficiency (and hence thermal efficiency) of the linear motor can be improved.
[0017]
Although it is preferable that the cylinder is entirely formed of an integrally molded product from the standpoint of axial alignment, a plurality of cylinder parts may be connected by bolts, nuts, etc. in consideration of cost reduction and the like.
[0020]
The Stirling engine of the present invention, packings may have a tapered shape as flow loss of the gas is reduced, the cross section of the gas passage widens toward the regenerator side (claim 2).
[0021]
For example, when the packing protruding into the gas passage has a surface perpendicular to the direction of the reciprocating motion, turbulence is generated at the ridgeline and the corner portion surrounding the surface, and it becomes difficult to greatly reduce the flow loss. As described above, turbulent flow or the like can be suppressed by making the cross section of the gas passage tapered toward the regenerator side. As a result, the flow loss can be further reduced, and the efficiency of the Stirling refrigerating engine can be improved.
[0022]
In the Stirling refrigerating engine of the present invention, the cylinder is cylindrical, and the packing can be a ring disposed in the gas passage end space of the annular gas passage located along the outer periphery of the cylinder (claim). 3 ).
[0023]
The ring can be determined by the cross-sectional shape and diameter according to the shape of the gas passage end space. For example, when forming with rubber | gum or resin, it can manufacture simply by an extrusion molding process. With this configuration, it is possible to improve the thermal efficiency of the Stirling refrigerating engine very easily and while suppressing an increase in cost. In addition, since the said ring is arrange | positioned in plenum space as mentioned above, it may be called a plenum ring.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0039]
(Embodiment 1)
1 is a cross-sectional view of a gas passage end space continuous with a compression space of a Stirling refrigerating engine according to Embodiment 1 of the present invention, cut along a plane including a piston shaft. The plenum ring 14 is disposed in contact with the flange portion 1 b in the gas passage end space 12 surrounded by the flange portion 1 b of the cylinder 1 and the casing 13. The gas passage end space 12 is connected to a vent hole 1 a formed in a cylinder that opens into the compression space 8.
[0040]
FIG. 2 is a perspective view of the cylinder 1 shown in FIG. 1 with the plenum ring 14 fitted therein. FIG. 1 is a sectional view taken along line II in FIG. The cylinder 1 is formed as an integral body including the flange portion 1b in order to obtain accurate axial alignment. For this reason, the vent hole 1a cannot be opened over the entire circumference of the cylinder 1, and the column part 1d that is not open is intermittently arranged around the cylinder.
[0041]
1 and 2, the vent hole 1a is shortened in the axial direction by the amount of the plenum ring. However, the gas passage from the compression space 8 to the regenerator 5 through the vent hole 1a and the high temperature side heat exchanger 10a is secured with a sufficiently low flow loss. For this reason, it is possible to sufficiently reduce the volume of the gas passage end space (plenum space) 12 while sufficiently reducing the flow loss of the gas. As a result, the thermal efficiency of this Stirling refrigerating engine can be improved by a simple structural change.
[0042]
The optimum shape and position of the plenum ring is determined by the trade-off between the contradictory requirements of low flow loss and narrow plenum space, depending on the operating conditions of the Stirling refrigeration engine. For example, in the case where the flange portion 1b of the cylinder protrudes toward the high temperature side heat exchanger 10a, the volume of the gas passage end space 12 is originally narrow. In such a case, as shown in FIG. 3, in order to reduce flow loss, a plenum ring having a small cross-sectional shape is arranged away from the vent hole 1a and in contact with the flange portion 1b.
[0043]
(Embodiment 2)
FIG. 4 is a cross-sectional view of the vicinity of the plenum space of the Stirling refrigerating engine according to Embodiment 2 of the present invention. In the present embodiment, the cross section of the plenum ring 14 is tapered so that the cross section of the gas passage becomes wider toward the high temperature side heat exchanger. In the plenum ring in the present embodiment, as shown in FIG. 5, a guide 14d is further provided at a portion in contact with the column portion 1d of the cylinder.
[0044]
FIG. 6 is a perspective view showing a state in which the plenum ring shown in FIG. 5 is fitted into a cylinder. Since the guide 14d is aligned with the column portion 1d of the cylinder, it does not become a resistance to gas flow. Rather, without this guide, the gas flows from the vent hole 1a to the cylinder column 1d and forms turbulence and stagnation. For this reason, flow resistance is increased. As shown in the present embodiment, by providing the guide 14d, there is no flow swirling around the cylinder pillar portion from the air hole 1a, and the flow loss is reduced. Therefore, it is desirable that the shape of the guide 14d be smoothly tapered so that the cross-sectional shape gradually decreases from the portion in contact with the cylinder column to the plenum ring body. The taper in the cross section of the plenum ring may be linear, or, as shown in FIG. 7, the taper surface may be a concave curved surface to enlarge the gas passage.
[0045]
(Embodiment 3)
In Embodiment 3 of the present invention, a material having low thermal conductivity is used for the plenum ring of the Stirling refrigerating engine in Embodiments 1 and 2 described above. With the arrangement of the plenum ring having a low thermal conductivity, it is possible to prevent a state in which heat escapes into the Stirling refrigerating engine through the flange portion of the cylinder. On the contrary, as shown in FIG. 8, when heat leaks through the flange portion 1b of the cylinder, the thermal efficiency of the high temperature side heat exchanger or radiator is lowered. Furthermore, the driving means for the piston such as a linear motor disposed on the outer periphery of the cylinder is heated to reduce the efficiency thereof. In the present embodiment, a plenum ring having a low thermal conductivity is disposed in contact with the flange portion 1b for the purpose of preventing the state shown in FIG.
[0046]
(Embodiment 4)
FIG. 9 is a cross-sectional view of the vicinity of the gas passage end space of the Stirling refrigerating engine according to Embodiment 4 of the present invention. In this embodiment, a plenum ring 14 and a ring fixing means 15 for adjusting and fixing the position of the plenum ring are provided. As the ring fixing means, for example, a screw or a pin 15 screwed into a female screw hole provided intermittently along the axial direction can be used.
[0047]
The plenum ring 14 is elastically pressed by the spring 17 toward the high temperature side heat exchanger 10a. When the ring fixing means is, for example, a screw that is screwed into a plurality of female screw holes arranged at appropriate intervals, the screw is screwed into a female screw at an appropriate position, and the screw is engaged with a recess provided on the outer peripheral surface of the plenum ring. The plenum ring can be fixed.
[0048]
For this reason, the plenum ring can be aligned and fixed at a position where the efficiency of the Stirling refrigerating engine is maximized.
[0049]
(Reference example)
FIG. 10 is a configuration diagram showing a Stirling refrigeration engine in a reference example . In the reference example , a linear motor 25 is used as a piston driving means. In the reference example , an operation state detection sensor that detects an operation state of the Stirling refrigerating engine is further provided. The operation state detection sensor is composed of the following sensors.
(A) Temperature sensor for detecting ambient air temperature (b) Temperature sensor for compression space, expansion space, radiator, heat absorber, etc. of Stirling refrigeration engine (c) Compression space, expansion space, piston, etc. for Stirling refrigeration engine (D) Driving means such as a piston, for example, a power sensor for detecting electric power supplied to a linear motor In each state detected by the above sensor, If the position of the plenum ring 14 for obtaining the maximum efficiency of the Stirling refrigerating engine is obtained in advance and stored in a data table or the like, the optimum position can be automatically determined according to each state. For this reason, it is possible to always obtain the maximum efficiency by adjusting the position of the plenum ring. An automatic ring moving means is used to move the position of the plenum ring. This automatic ring moving means includes a spring 17 that elastically presses the ring and a pin 15 that engages with the outer peripheral recess of the ring. Furthermore, for example, an automatic moving mechanism 18 including a motor that moves the pin in a long hole along the axis, a motor that moves the pin up and down and engages the pin with the plenum ring, and the like can be used.
[0050]
The automatic moving mechanism 18 including the motor is moved toward the position by the control device 19 deciding the moving position. A signal is transmitted to this control device from at least one of the various sensors described above, for example, the temperature sensor 20 of the radiator 11, and the plenum ring 14 is automatically set at a pre-stored optimum position according to the value of the signal. Move to.
[0051]
As a result, even when the state of the Stirling refrigerating engine changes from moment to moment, the maximum efficiency at that time can always be automatically obtained. For this reason, high efficiency can be ensured and a wide range of application fields can be obtained.
[0052]
While the embodiments of the present invention have been described above, the scope of the present invention disclosed above is merely an example, and the scope of the present invention is not limited to these embodiments. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.
[0053]
【The invention's effect】
By using the Stirling refrigeration engine of the present invention, it is possible to satisfy both the reduction of the volume of the gas passage end space and the reduction of the flow loss of the gas flow, without complicated processing, and the thermal efficiency. Improvements can be realized. Furthermore, by configuring the filling with a material having a lower thermal conductivity than the cylinder, it is possible to prevent heat from leaking into the Stirling engine and further improve the thermal efficiency.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of the vicinity of a plenum space of a Stirling refrigerating engine according to Embodiment 1 of the present invention.
2 is a perspective view of a state in which a plenum ring is fitted into a cylinder of the Stirling refrigerating engine of FIG. 1. FIG.
FIG. 3 is a cross-sectional view of the vicinity of a plenum space of a Stirling refrigerating engine according to a modification of the first embodiment of the present invention.
FIG. 4 is a cross-sectional view of the vicinity of a plenum space of a Stirling refrigerating engine according to Embodiment 2 of the present invention.
5 is a perspective view showing a plenum ring arranged in a gas passage end space of the Stirling refrigerating engine of FIG. 4; FIG.
6 is a perspective view showing a state in which the plenum ring of FIG. 5 is fitted into the cylinder of FIG. 4;
FIG. 7 is a cross-sectional view of the vicinity of a plenum space of a Stirling refrigerating engine according to a modification of the second embodiment of the present invention.
FIG. 8 is a drawing showing heat leakage in a conventional Stirling refrigerating engine which is a comparative example for the Stirling refrigerating engine of Embodiment 3 of the present invention.
FIG. 9 is a cross-sectional view of the vicinity of a plenum space of a Stirling refrigerating engine according to Embodiment 4 of the present invention.
FIG. 10 is a configuration diagram of a Stirling refrigerating engine in a reference example .
FIG. 11 is a configuration diagram of a conventional Stirling refrigerating engine.
FIG. 12 is a cross-sectional view of the vicinity of the plenum space of a modified example of a conventional Stirling refrigerating engine.
FIG. 13 is a cross-sectional view of the vicinity of the plenum space of another modification of the conventional Stirling refrigerating engine.
[Explanation of symbols]
1 cylinder, 1a vent, 1b flange, 2 piston, 3 displacer, 4 displacer rod, 5 regenerator, 6 spring, 8 compression space, 9 expansion space, 10a high temperature side heat exchanger, 10b low temperature side heat exchanger, 11 radiator, 12 gas passage end space, 13 casing, 14 plenum ring, 14d guide, 15 position fixing pin (screw), 16 heat absorber, 17 ring spring, 18 automatic movement mechanism, 19 control device, 20 temperature sensor, 25 Linear motor.

Claims (3)

A cylinder, a reciprocating displacer in the cylinder, and a piston driven by driving means; an expansion space between the displacer and the cylinder end portion; and a space between the displacer and the piston. A Stirling refrigeration engine having a compression space, and further comprising a regenerator that thermally isolates the compression space and the expansion space in a gas passage outside the cylinder that communicates the compression space and the expansion space. And
In the gas passage, the volume of the gas passage end space is such that the gas passage end space connected to the vent hole opened in the cylinder opening to the compression space does not block the flow of the gas passage. Fixing the filler to reduce the contact with the cylinder,
A Stirling refrigerating engine, wherein the filling is made of a material having lower thermal conductivity than the cylinder . The Stirling refrigerating engine according to claim 1 , wherein the filling has a tapered shape in which a cross section of the gas passage becomes wider toward the regenerator so that a flow loss of the gas is reduced. The Stirling according to claim 1 or 2 , wherein the cylinder is cylindrical, and the filling is a ring disposed in the gas passage end space of an annular gas passage located along an outer periphery of the cylinder. Refrigeration engine.

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