JP2004232508A - Stirling engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Stirling engine causing no damage of a piston and a piston support spring when assembling the Stirling engine (when sealing an operating medium), and restraining dislocation of a reciprocating motion central position of the piston. <P>SOLUTION: This Stirling engine is formed by dividing the inside of a pressure vessel 4 into first and second operation spaces 7a and 7b and a back face space 8 by a displacer 2 and the piston 1 for reciprocatingly sliding inside a cylinder 3, and has a first passage 1c arranged in the piston 1 and connecting the first operation space 7a and a piston sliding surface 1a and a second passage 3b arranged in the cylinder 3 and connecting the back face space 8 and a cylinder sliding surface 3a, and is formed by communicating the first and second passages 1c and 3b by both (at least two places) on the back face space 8 side and the first operation space 7a side more than an initial reciprocating motion central position of the piston 1. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a Stirling engine that obtains low temperature / high temperature or electric power / power by utilizing the compression / expansion of a working gas accompanying reciprocation of a piston and a displacer.
[0002]
[Prior art]
FIG. 8 is a schematic sectional view showing a conventional configuration of a Stirling refrigerator, which is one of the Stirling engines. The Stirling refrigerator shown in this figure has a piston 1 and a displacer 2 that smoothly slide back and forth on the inner surface of a cylinder 3 (cylinder sliding surface 3a). The piston 1 and the displacer 2 are arranged coaxially, and a rod 2 a forming one end of the displacer 2 penetrates a sliding hole 1 b provided in the center of the piston 1. The piston 1 and the displacer 2 are elastically supported by the pressure vessel 4 via a piston support spring 5 and a displacer support spring 6, respectively.
[0003]
The internal space of the pressure vessel 4 is divided by the piston 1 into two spaces. One is a working space 7 on the side of the displacer 2 when viewed from the piston 1, and the other is a back space 8 on the opposite side of the working space 7 from the piston 1, that is, the end side of the cylinder 3. These spaces are filled with a working medium such as high-pressure helium gas. The working space 7 is further divided into two spaces by the displacer 2. One is a first working space 7a (compression space) sandwiched between the piston 1 and the displacer 2, and the other is on the opposite side of the first working space 7a from the displacer 2, that is, on the tip side of the cylinder 3. This is the second working space 7b (expansion space). The two working spaces are connected via a regenerator 9.
[0004]
The piston 1 is reciprocated at a predetermined cycle by a drive unit (not shown) such as a linear motor. Thereby, the working medium is compressed and expanded in the working space 7. The displacer 2 is linearly reciprocated by a pressure change accompanying the compression and expansion of the working medium. At this time, the piston 1 and the displacer 2 reciprocate at the same cycle with a predetermined phase difference.
[0005]
In the Stirling refrigerator having the above configuration, an operating space 7 and a back space 8 are provided between the cylinder sliding surface 3a and the piston sliding surface 1a and between the rod 2a and the piston sliding hole 1b. A shut off gas seal is provided. The gas seal is realized by providing a seal ring between members that come into contact with each other, or by fitting both members with high precision.
[0006]
However, no matter what kind of gas seal is applied, the working space 7 and the back space 8 cannot be completely shut off, and it is inevitable that the working medium flows through both spaces through a minute gap. Therefore, when the piston 1 is moving in the direction of the working space 7, the pressure in the first working space 7 a becomes higher than the pressure in the back space 8, and the working medium flows from the first working space 7 a to the back space 8. . Conversely, when the piston 1 is moving in the direction of the back space 8, the pressure of the first working space 7a becomes lower than the pressure of the back space 8, and the working medium flows from the back space 8 to the first working space 7a. I do.
[0007]
Here, the pressure difference between the first working space 7a and the back space 8 is larger when the piston 1 is moving in the working space 7 direction than when the piston 1 is moving in the back space 8 direction. Therefore, the working medium in the first working space 7a flows out to the back space 8 little by little in each cycle of the reciprocating movement of the piston 1. If such a situation is left unchecked, the pressure in the back space 8 gradually increases, and the center position of the reciprocating motion of the piston 1 shifts from the initial position to the working space 7 side, and the piston 1 is moved to the physical movement limit. The position may be reached, the piston 1 may collide with the displacer 2, or the displacer 2 may collide with the pressure vessel 4.
[0008]
In view of this, Patent Literature 1 discloses a technique for suppressing the displacement of the reciprocating center of the piston by maintaining the pressure balance between the working space and the back space. FIG. 9 is a schematic sectional view showing the configuration of the Stirling refrigerator disclosed in Patent Document 1. In the Stirling refrigerator shown in the figure, the piston 1 has a first flow path 1c connecting the first working space 7a and the piston sliding surface 1a, and the cylinder 3 is composed of a back space 8 and a cylinder sliding surface 3a. Are connected to each other. Note that the opening 1d of the first flow path 1c (on the side of the piston sliding surface 1a) and the opening 3c of the second flow path 3b (on the side of the cylinder sliding surface 3a) move the piston 1 to the initial reciprocation center position. They are arranged so as to face each other only when there is a certain time.
[0009]
However, as the applicant has proposed in Japanese Patent Application No. 2002-259854, even if such a flow path is provided, the pressure in the back space 8 is actually higher than that in the working space 7, and the reciprocation of the piston 1 is caused. The movement center position is shifted from the initial position to the working space 7 side.
[0010]
Therefore, as a technique for solving the above-mentioned problem, in Japanese Patent Application No. 2002-259854, the present applicant communicates the first flow path 1c and the second flow path 3b on the back space 8 side with respect to the initial reciprocating center position of the piston 1. A technique has been proposed in which the displacement of the center of the reciprocating motion of the piston 1 is suppressed by causing the piston 1 to shift. FIG. 10 is a schematic sectional view showing a configuration of a Stirling refrigerator described in Japanese Patent Application No. 2002-259854. In the Stirling refrigerator shown in this figure, the piston 1 has a first flow path 1c that communicates the first working space 7a with the piston sliding surface 1a, and the cylinder 3 has a back space 8 and a cylinder sliding surface. It has a second flow path 3b communicating with 3a. The opening of the first flow passage 1c on the side of the piston sliding surface 1a (hereinafter referred to as the first flow passage opening 1d) and the opening 3c of the second flow passage 3b on the side of the cylinder sliding surface 3a (hereinafter, referred to as the first passage 1c). , The second flow path opening 3c) are arranged so as to face each other only when the piston 1 is closer to the back space 8 than the initial reciprocation center position.
[0011]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-039222
[Problems to be solved by the invention]
Certainly, in the case of the Stirling refrigerator described in Japanese Patent Application No. 2002-259854, the flow from the first working space 7a to the back space 8 in each cycle of the reciprocating motion of the piston 1 near the initial reciprocating motion center position of the piston 1. And the working medium flow rate flowing from the back space 8 to the first working space 7a can be balanced.
[0013]
However, when assembling the Stirling refrigerating machine having the above-described configuration, when the operation for enclosing the working medium is started when the first passage opening 1d is on the working space 7 side with respect to the second passage opening 3c. The working medium cannot smoothly flow into the working space, which may cause a new problem.
[0014]
That is, when the operation of enclosing the working medium from the working medium inlet 10 provided in the back space 8 is started, there is no flow path for the working medium to flow from the back space 8 to the working space 7 side. Cannot flow, and the pressure of the working medium in the back space 8 starts to rise. Then, the piston 1 moves toward the working space 7 under the influence of the pressure rise, but since the first flow path opening 1d and the second flow path opening 3c do not face each other, the piston 1 The movement of the piston 1 toward the working space 7 is continued, and the piston 1 reaches a physical movement limit position, and the piston 1 and the piston support spring 5 are damaged.
[0015]
In the Stirling refrigerator described in Japanese Patent Application No. 2002-259854, the first flow path 1c and the second flow path 3b are located closer to the back space 8 than the initial reciprocating center of the piston 1 as shown in FIG. There is also proposed a configuration in which the piston 1 communicates with the piston 1 even at the initial reciprocation center position.
[0016]
However, even in the Stirling refrigerator having the above-described configuration, when the working medium is sealed in the Stirling refrigerator, the initial position of the piston 1 is shifted toward the working space 7 due to the weight of the piston 1 as shown in FIG. When the first passage opening 1d and the second passage opening 3c do not face each other and the working medium is sealed from the back space 8 side, there is no flow passage through which the working medium flows in the working space 7 side, and the piston 1 Is pushed toward the working space 7, the piston 1 reaches the physical movement limit position, and the piston 1 and the piston support spring 5 are damaged.
[0017]
In view of the above problems, an object of the present invention is to provide a Stirling engine in which a piston and a piston support spring are not damaged at the time of assembling the Stirling engine, and the displacement of the reciprocating center of the piston is suppressed.
[0018]
[Means for Solving the Problems]
In order to achieve the above object, a Stirling engine according to the present invention includes a piston that reciprocates inside a cylinder, and a working medium that opposes the piston inside the cylinder and that is compressed and expanded by the movement of the piston. A first working space between the piston and the displacer, a second working space on the opposite side of the first working space as viewed from the displacer, and a second working space as viewed from the piston. A Stirling engine, which is hermetically sealed so as to have a back space on the side opposite to the first working space, a first flow path provided in the piston and connecting the first working space and an outer surface of the piston; And a second flow path connecting the back space and the inner surface of the cylinder, and the first and second flow paths are used for the initial reciprocating movement of the piston. The center position comprising communicates with both of the rear space side and the first working space side (at least two places).
[0019]
Specifically, a plurality of openings of the first flow path provided on the outer surface of the piston are provided, one of which is offset to the first working space side from the initial reciprocating movement center position of the piston, and the other is the piston May be offset to the back space side from the initial reciprocation center position. Alternatively, a plurality of openings of the second flow path provided on the inner surface of the cylinder are provided, one of which is offset to the back space side from the initial reciprocation center position of the piston, and the other is the initial reciprocation of the piston. It is preferable to offset the first working space from the center position.
[0020]
With such a configuration, it is possible to assemble the Stirling engine without damaging the piston or the piston support spring when the Stirling engine is assembled (when the working medium is filled).
[0021]
In the Stirling engine having the above-described configuration, the opening of the first flow path may have a different shape and / or sectional area depending on the position. Alternatively, with respect to the second flow path, the shape and / or cross-sectional area of the opening may be changed according to the position. With this configuration, it is possible to adjust the flow rate of the working medium when the first and second flow paths communicate with each other. Can be suppressed.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
First, a first embodiment of a Stirling refrigerator according to the present invention will be described in detail with reference to FIGS. FIG. 1 is a schematic sectional view showing a first embodiment of a Stirling refrigerator according to the present invention, and FIG. 2 is a schematic sectional view showing a peripheral structure of a piston in the first embodiment. In the embodiments described below, the same members as those in the conventional configuration described above are denoted by the same reference numerals as those in FIGS.
[0023]
As shown in FIG. 2, in the Stirling refrigerator of the present embodiment, the first flow path opening 1d and the second flow path opening 3c are arranged such that the piston 1 is closer to the back space 8 than the initial reciprocating movement center position. It is arranged so as to oppose both sides (at least two places) of the one working space 7a side. Specifically, the first flow path opening 1d is divided into an operation space side first flow path opening 1e and a back space side first flow path opening 1f. The center position of the reciprocating motion of the piston 1 is offset toward the working space 7 from the initial position, and the back space side first flow path opening 1f is offset toward the back space 8 from the initial reciprocating center position of the piston 1. The second flow path opening 3c is disposed at the initial reciprocating center position of the piston 1. The working space side first flow path opening 1e and / or the back space side first flow path opening 1f may be provided in two or more places. Further, a plurality of portions may be provided on the same circumference of the piston sliding surface 1a. In this case, the second flow path opening 3c is provided on the same circumference of the cylinder sliding surface 3a in correspondence with the opening 1d. Provide multiple locations.
[0024]
Here, when assembling the Stirling refrigerator, when the working medium is sealed from the back space 8 side, the piston 1 is pushed toward the first working space 7a side as shown in FIG. And the second flow path opening 3c of the cylinder 3 moves until they face each other. When the back space side first flow path opening 1f and the second flow path opening 3c face each other, the working medium flows from the back space 8 to the first working space 7a through the first flow path 1c and the second flow path 3b. The working medium can be sealed up to a predetermined pressure without the piston 1 being pushed further and the piston 1 and the piston support spring 5 being damaged.
[0025]
Even if the position of the piston 1 is slightly shifted to the working space 7 side due to the influence of its own weight or the like, the first space opening 1f on the back space side of the piston 1 is connected to the second passage opening 3c of the cylinder 3. So that the first space opening 1f of the piston 1 is located on the back space 8 side, or the first space opening 1f of the back space faces the second passage opening 3c. It is necessary to set the offset amount of the road opening 1f.
[0026]
When the offset amount is increased, the flow rate of the working medium flowing from the first working space 7a to the back space 8 during operation of the Stirling refrigerator increases, so that the pressure in the back space 8 increases and the center position of the reciprocating motion of the piston 1 increases. Is moved to the working space 7 side, so it is desirable to minimize the offset amount to the back space 8 side. With such a configuration, at the time of assembling the Stirling refrigerator, the working medium can be sealed without damaging the piston 1 and the piston support spring 5.
[0027]
Next, a second embodiment of the Stirling refrigerator according to the present invention will be described in detail with reference to FIGS. FIG. 4 is a schematic sectional view showing a peripheral structure of a piston according to the second embodiment.
[0028]
As shown in FIG. 4, in the Stirling refrigerator of the present embodiment, the first flow path opening 1 d and the second flow path opening 3 c are formed such that the piston 1 is closer to the back space 8 than the initial reciprocating center position and to the working space. It is arranged so as to oppose both sides (at least two places) on the seven sides. More specifically, the second flow path opening 3c is divided into a working space side second flow path opening 3d and a back space side second flow path opening 3e. The initial position of the center position of the reciprocating motion of the piston 1 is offset to the working space 7 side, and the rear space side second flow path opening 3e is offset to the side of the back space 8 from the initial position of the reciprocating center position of the piston 1. The first flow path opening 1d is provided at an initial position of the center position of the reciprocating motion of the piston 1. The working space side second flow path opening 3d and / or the back space side second flow path opening 3e may be provided in two or more places. Further, a plurality of portions may be provided on the same circumference of the cylinder sliding surface 3a. In this case, the first flow path opening 1d is provided on the same circumference of the piston sliding surface 1a in correspondence with the opening 3c. At multiple locations.
[0029]
Here, when assembling the Stirling refrigerator, when the working medium is sealed from the back space 8 side, the piston 1 is pushed to the first working space 7a side as shown in FIG. Is moved until it faces the working space side second flow path opening 3d. When the first flow path opening 1d and the working space side second flow path opening 3d face each other, the working medium flows from the back space 8 to the first working space 7a through the first flow path 1c and the second flow path 3b. The working medium can be sealed up to a predetermined pressure without the piston 1 being pushed further and the piston 1 and the piston support spring 5 being damaged.
[0030]
Even when the position of the piston 1 is slightly shifted to the working space 7 side due to the influence of its own weight or the like, the working space side second flow passage opening 3d of the cylinder 3 is connected to the first flow passage opening 1d of the piston 1. Or the working space side second flow path of the cylinder 3 so that the working space side second flow path opening part 3d faces the first flow path opening part 1d. It is necessary to set the offset amount of the road opening 3d. In addition, when the offset amount is increased, the first passage opening 1c and the working space side second passage opening 3d face each other when the pressure difference between the first working space 7a and the back space 8 is large. Therefore, the flow rate of the working medium flowing from the first working space 7a to the back space 8 during the operation of the Stirling refrigerator increases, whereby the pressure in the back space 8 increases, and the center position of the reciprocating motion of the piston 1 is reduced. It is desirable that the amount of offset to the working space 7 be minimized because it causes movement to the working space 7 side. With such a configuration, at the time of assembling the Stirling refrigerator, the working medium can be sealed without damaging the piston 1 and the piston support spring 5.
[0031]
Next, a third embodiment of the Stirling refrigerator according to the present invention will be described in detail with reference to FIG. FIG. 6 is a schematic sectional view showing a structure around a piston according to the third embodiment. As shown in the figure, the Stirling refrigerator of the present embodiment changes the shape and / or cross-sectional area of the first flow path opening 1d of the piston 1 according to the position in addition to the configuration of the first embodiment. Configuration. With this configuration, it is possible to suppress the movement of the center position of the reciprocating motion of the piston 1 toward the working space 7 while suppressing the performance of the Stirling refrigerator due to the useless flow of the working medium.
[0032]
Here, when the cross-sectional area of the back space side first flow path opening 1f is increased, the flow rate of the working medium flowing from the first working space 7a to the back space 8 increases during the operation of the Stirling refrigerator, thereby increasing the back surface. Since the pressure in the space 8 increases and the center position of the reciprocating motion of the piston 1 moves to the working space 7 side, the cross-sectional area of the back space side first flow passage opening 1f is equal to the working space side first flow passage. It is desirable that the cross-sectional area be smaller than the cross-sectional area of the opening 1e and be minimized. With such a configuration, the piston 1 and the piston support spring 5 are not damaged at the time of assembling the Stirling refrigerator, and the performance of the Stirling refrigerator is prevented from deteriorating due to useless flow of the working medium. The movement of the center position of the reciprocating movement toward the working space 7 can be suppressed.
[0033]
That is, the back space side first flow path opening 1f is for enclosing the working medium in the back space 8 and the working space side first flow path opening 1e is provided for the working space 7 at the center position of the reciprocating motion of the piston 1. The medium flow rate in the working space side first flow path opening 1e during the reciprocating movement of the piston 1 is controlled by the medium flow rate in the back space side first flow path opening 1f and the first flow rate. The cross-sectional area is set so as to be equal to the flow rate of the medium leaking from the working space 7a to the back space 8.
[0034]
Next, a fourth embodiment of the Stirling refrigerator according to the present invention will be described in detail with reference to FIG. FIG. 7 is a schematic sectional view showing a structure around a piston according to the fourth embodiment. As shown in the drawing, the Stirling refrigerator of the present embodiment changes the shape and / or cross-sectional area of the second passage opening 3c of the cylinder 3 according to the position in addition to the configuration of the second embodiment. Configuration. With this configuration, it is possible to suppress the movement of the center position of the reciprocating motion of the piston 1 toward the working space 7 while suppressing the performance of the Stirling refrigerator due to the useless flow of the working medium.
[0035]
Here, when the cross-sectional area of the working space side second flow path opening 3d is increased, the flow rate of the working medium flowing from the first working space 7a to the back space 8 increases during the operation of the Stirling refrigerator, thereby increasing the rear surface. Since the pressure in the space 8 increases and the center position of the reciprocating motion of the piston 1 moves to the working space 7 side, the cross-sectional area of the working space side second flow passage opening 3d is the rear space side second flow passage. It is desirable that the cross-sectional area be smaller than the cross-sectional area of the opening 3e and be minimized. With such a configuration, the piston 1 and the piston support spring 5 are not damaged at the time of assembling the Stirling refrigerator, and the performance of the Stirling refrigerator is prevented from deteriorating due to useless flow of the working medium. The movement of the center position of the reciprocating movement toward the working space 7 can be suppressed.
[0036]
In the above embodiment, the case where the present invention is applied to a Stirling refrigerator is described as an example.However, the application target of the present invention is not limited to this, and a Stirling engine, a generator, It can be widely applied to general Stirling engines such as heat pumps and compressors.
[0037]
【The invention's effect】
As described above, according to the present invention, it is possible to realize a Stirling engine that can prevent a piston and a piston support spring from being damaged when a working medium is filled in assembling a Stirling engine and can suppress a shift of a reciprocating center position of a piston during operation. Can be.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a first embodiment of a Stirling refrigerator according to the present invention.
FIG. 2 is a schematic sectional view showing a peripheral structure of a piston according to the first embodiment of the present invention.
FIG. 3 is a schematic sectional view showing a peripheral structure of a piston when a flow path communicates with the first embodiment of the present invention.
FIG. 4 is a schematic sectional view showing a structure around a piston according to a second embodiment of the present invention.
FIG. 5 is a schematic cross-sectional view illustrating a structure around a piston when a flow path is connected according to a second embodiment of the present invention.
FIG. 6 is a schematic sectional view showing a peripheral structure of a piston according to a third embodiment of the present invention.
FIG. 7 is a schematic sectional view showing a peripheral structure of a piston according to a fourth embodiment of the present invention.
FIG. 8 is a schematic sectional view showing one conventional configuration of a Stirling refrigerator.
FIG. 9 is a schematic sectional view showing a configuration of a Stirling refrigerator disclosed in Patent Document 1.
FIG. 10 is a schematic sectional view showing the configuration of a Stirling refrigerator filed by the applicant in advance.
FIG. 11 is a schematic sectional view showing a structure around a piston in a Stirling refrigerator filed by the applicant in advance.
FIG. 12 is a schematic cross-sectional view showing a piston peripheral structure when a piston position is shifted in a Stirling refrigerator filed by the applicant in advance.
[Explanation of symbols]
1 Piston 1a Piston sliding surface 1b Piston sliding hole 1c First flow path (piston side flow path)
1d First flow path opening 1e Working space side first flow path opening 1f Back space side first flow path opening 2 Displacer 3 Cylinder 3a Cylinder sliding surface 3b Second flow path (cylinder side flow path)
3c Second flow path opening 3d Working space side second flow path opening 3e Back space side second flow path opening 5 Piston support spring 7 Working space 7a First working space 8 Back space

Claims (5)

A piston reciprocating inside the cylinder, and a displacer opposed to the piston inside the cylinder and driven by the action of a working medium compressed and expanded by the movement of the piston, wherein the piston and the displacer A second working space on the opposite side of the first working space as viewed from the displacer, and a back space on the opposite side of the first working space as viewed from the piston. In a sealed Stirling engine,
A first flow path provided in the piston and communicating the first working space with the outer surface of the piston; and a second flow path provided in the cylinder and communicating the back space and the inner surface of the cylinder. A Stirling engine, wherein the first and second flow paths are communicated on both the back space side and the first working space side with respect to the initial reciprocating movement center position of the piston. A plurality of openings of the first flow path provided on the outer surface of the piston are provided, one of which is offset to the first working space side from the initial reciprocation center position of the piston, and the other is the initial reciprocation of the piston. 2. The Stirling engine according to claim 1, wherein the Stirling engine is formed so as to be offset toward the back space side from the exercise center position. A plurality of openings of the second flow path provided on the inner surface of the cylinder are provided, one of which is offset to the back space side from the initial reciprocation center position of the piston, and the other is the initial reciprocation center of the piston. The Stirling engine according to claim 1, wherein the Stirling engine is formed so as to be offset from the position toward the first working space. The Stirling engine according to claim 2, wherein the plurality of openings of the first flow path have different shapes and / or cross-sectional areas depending on positions. The Stirling engine according to claim 3, wherein the plurality of openings of the second flow path have different shapes and / or cross-sectional areas depending on positions.

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