JP2005003245A - Pulse tube refrigerator - Google Patents

Abstract

Provided is a pulse tube refrigerator that realizes both an increase in rectification effect, reduction in energy loss such as pressure loss and temperature rise, and space saving by rectifying over a short distance, and greatly improved total performance. .
A pulse tube that forms a flow path by connecting a compressor, a regenerator, a low temperature end, a pulse tube, and a phase control unit in series, and generates cold at the low temperature end by heat exchange of working gas flowing through the flow path. In the refrigerator, a rectifying unit 12 having a configuration in which two porous plates 12a are arranged with a space 12d interposed therebetween is used as a pulse tube refrigerator that rectifies the working gas flowing into the pulse tube.
[Selection] Figure 1

Description

【００２８】
上記数１〜数３の式は多孔板が１枚の時の理論式であり、複数枚（例えば２枚）の場合の理論式は確立されていない。そこで図２（ａ）の減衰率−抵抗係数特性図から数式を算出し、実験式とした。実験式は次式で示すようになる。
【００２９】
【数４】
｜Ａ_∞｜＝０．２１６４Ｋ^４−１．２０１６Ｋ^３＋２．５２４５Ｋ^２−２．５８６８Ｋ＋１．１７８２ ：Ｋ≦２
｜Ａ_∞｜＝−０．００４９Ｋ^３＋０．０６２８Ｋ^２−０．２５０９Ｋ＋０．２０５７ ：２≦Ｋ≦５
但し、Ｌ／λ＝０．２（＝Ｌ／Ｄ）の場合である。
【００３０】
ここで、Ｌおよびλは、図２（ｂ）で示すように、多孔板間の隙間および擾乱の波長（円管の場合は外径Ｄに相当）である。図２（ａ）の意味するところは、例えば同じ抵抗係数Ｋ＝１をもつ多孔板を持つ場合、１枚では擾乱を０．４までしか減衰できないことに対して、２枚入れることで０．１３まで減衰することができる。すなわち、単純にＮ倍の効果ではなく、Ｎ乗程度の効果を得ることができる。
【００３１】
以上のことから、多孔板を２枚使用する場合には１枚当たりのΔｐは小さくできるため、厚さｔを小さくしたり、開口率Ｂを大きくしたりと、設置スペース低減等の設計上の自由度を大きく向上することができる。
【００３２】
なお、本発明では整流部に熱交換機能も同時に持たせるために、熱交換能力を考慮する。その場合には、多孔板内ガス温度と電熱面における温度差ΔＴを指標に考える。
図２（ｂ）で示すように、多孔板の場合には、ある一定の外径Ｄに対して開けられ孔（径ｄ）の数は、孔径ｄとピッチｐを決めた時点で決まる。したがって必然的に開口率Ｂ（＝Ａ_ｄ／Ａ_ｄ）も決まる。
【００３３】
それでは、実際に計算してみる。現状の１枚のみの多孔板を基準に取る。その寸法を孔径ｄ／Ｄ＝０．１、厚さｔ／Ｄ＝０．５、開口率Ｂ＝０．６とし、例えば開口率Ｂを同程度（０．５４〜０．６）に取って２枚使用時の減衰率Ａ_∞と温度差ΔＴを比較したものを図３に示す。また、この時の多孔板の厚さをｔ／Ｄ＝０．１とし、多孔板間の隙間をＬ／Ｄ＝０．２として計算した。
【００３４】
図３で示すように、２枚時の孔径を変化させて穴数を増加させると、ガスとの接触面積が増大するため、熱交換能力の指標である温度差ΔＴが減少すると同時に、減衰率は低減していく。
逆に圧力損失は接触面積が増大するために増加傾向にある。
【００３５】
本計算例の場合には厚さ０．０５の時に１枚時と同程度の圧力損失（１．００と１，１３）で減衰率を０．１４５→０．０９８に低減させ、温度差を２．２６→１．３９とし、トータル能力を増大させることが可能である。
さらに、設置スペースとして軸方向の総長さ（厚さ）を０．５→０．４（＝０．１×２＋０．２）と低減することが可能である。
【００３６】
本計算例では、多孔板の厚さ、開口率、隙間などを固定して計算したが、これらのパラメータを自由に設定することであらゆる設計が可能である。
【００３７】
続いて本発明の第２実施形態について図を参照しつつ説明する。図４は本実施形態のパルス管冷凍機の要部となる低温端の構成図であり、図４（ａ）は端部本体内を上側から見た図、図４（ｂ）は低温端の側断面図である。
本実施形態のパルス管冷凍機は、図６を用いて説明した従来技術のパルス管冷凍機の構成とほぼ同じであり、図６に示すように、パルス管１１０、圧縮機１２０、蓄冷器１３０、位相制御部１４０を備える点は同じであるが、低温端１５０に代えて、図４で示すような低温端２０を採用した点が相違している。以下、低温端２０の構成およびその改良点について説明する。なお、それ以外の構成および冷凍原理は同じであるため、重複する説明を省略する。
【００３８】
本実施形態の低温端２０は、図４で示すように、端部本体２１、整流部２２を備えている。さらに端部本体２１内には、作動ガスの流路となる空間である熱交換部２３が形成される。
【００３９】
整流部２２は、図４（ａ），（ｂ）で示すように、上側（パルス管から離れた側）に大径多孔板２２ａ、環体２２ｂ、下側（パルス管に近い側）に小径多孔板２２ｃを備えている。大径多孔板２２ａは、図４（ａ），（ｂ）で示すように、所定厚さｔの板に、多数の大径孔部２２ｄが形成されている。また、大径多孔板２２ａは、図４（ｂ）で示すように、所定厚さｔの板に、多数の小径孔部２２ｅが形成されている。
【００４０】
このような大径多孔板２２ａと小径多孔板２２ｃとが環体２２ｂを挟持したとき、空間部２２ｆが形成される。このように整流部２２は、大径多孔板２２ａと小径多孔板２２ｃという２枚の多孔板で１個の空間部２２ｆを挟むような構成となる。
このような整流部２２は、パルス管１１０（図６参照）への作動ガスの出入口であって、パルス管１１０と熱交換部２３との間に配置されることとなる。
【００４１】
このように本実施形態では、熱交換部側、つまりに乱れが大きい側（折り返し側）で孔径が大きい大径多孔板２２ａを配置し、また、パルス管側で孔径の小さい小径多孔板２２ｃを配置した。
これにより、容易に所望の減衰率と温度差とを得ることが可能である。例えば、先に説明した計算例を用いるとパルス管側でｄ／Ｄ＝０．０４、折り返し側でｄ／Ｄ＝０．０５を組み合わせることで、その中間の能力の低温端を形成することができる。
【００４２】
これら第１，第２実施形態では整流部は２枚であるものとして説明したが、３枚以上の組合せも可能である。図５は、３枚の多孔板を有する整流部の側断面図である。
図５（ａ）で示すように、整流部３０は、孔径が同じ多孔板３１を３枚、中心に空間部３２ａを有する円環３２を２個それぞれ備え、２個の空間部３２ａと３枚の多孔板３１と交互に配置した構成を有するようにしても良い。
さらに、図５（ｂ）で示すように、整流部４０は、孔径がそれぞれ異なる大径多孔板４１、中径多孔板４２、小径多孔板４３、中心に空間部４４ａを有する円環４４を２個それぞれ備え、２個の空間部４４ａと３枚の大径多孔板４１、中径多孔板４２、小径多孔板４３と交互に配置した構成を有するようにしても良い。
【００４３】
このような整流部の構成について一般化すると、ｎ（ｎは１以上の自然数）の空間部と（ｎ＋１）枚の多孔板と交互に配置した構成を有し、パルス管の出入口に配置される。なお、パルス管の出入口ではパルス管と熱交換部との間の流路に配置されることが少なくとも必要であるが、これに加えてパルス管とイナータンスチューブとの間に配置しても良い。
【００４４】
さらに、孔径を同径とするか（第１実施形態）あるいパルス管から離れた側（熱交換部側）で大径とし、また、パルス管側で小径となる（第２実施形態）ように構成する。
このような基準に則る各種の整流部とすれば、整流効果を高めることが可能となる。
【００４５】
【発明の効果】
以上述べたように本発明によれば、整流効果の増大、圧力損失や温度上昇といったエネルギーロスの低減、および、短い距離で整流する省スペース化を共に実現し、トータル的な性能を大幅に向上したパルス管冷凍機を提供することができる。
【図面の簡単な説明】
【図１】本発明の第１実施形態のパルス管冷凍機の要部となる低温端の構成図であり、図１（ａ）は端部本体内を上側から見た図、図１（ｂ）は低温端の側断面図である。
【図２】減衰率と抵抗係数の関係を説明する説明図であり、図２（ａ）は減衰率−抵抗係数線図、図２（ｂ）は変数の説明図である。
【図３】減衰率−温度差線図である。
【図４】本発明の第２実施形態のパルス管冷凍機の要部となる低温端の構成図であり、図４（ａ）は端部本体内を上側から見た図、図４（ｂ）は低温端の側断面図である。
【図５】３枚の多孔板を有する整流部の側断面図である。
【図６】従来技術のパルス管冷凍機の概略構成図である。
【図７】従来技術の低温端の構成図で、図７（ａ）は端部本体内を上側から見た図、図７（ｂ）は低温端の側断面図である。
【符号の説明】
１０ ：低温端
１１ ：端部本体
１２ ：整流部
１２ａ ：多孔板
１２ｂ ：環体
１２ｃ ：孔部
１２ｄ ：空間部
１３ ：熱交換部
２０ ：低温端
２１ ：端部本体
２２ ：整流部
２２ａ ：大径多孔板
２２ｂ ：環体
２２ｃ ：小径多孔板
２２ｄ ：大径孔部
２２ｅ ：小径孔部
２２ｆ ：空間部
２３ ：熱交換部
３０ ：整流部
３１ ：多孔板
３２ ：環体
３２ａ ：空間部
４０ ：整流部
４１ ：大径多孔板
４２ ：中径多孔板
４３ ：小径多孔板
４４ ：環体
４４ａ ：空間部
１００ ：パルス管冷凍機
１１０ ：パルス管
１１１ ：ガスピストン
１２０ ：圧縮機
１２１ ：シリンダ
１２２ ：ピストン
１３０ ：蓄冷器
１４０ ：位相制御部
１４１ ：イナータンスチューブ
１４２ ：バッファタンク
１５０ ：低温端
１５１ ：熱交換部
１５２ ：整流部
１５３ ：孔部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pulse tube refrigerator used as a cryogenic refrigerator.
[0002]
[Prior art]
First, the configuration of a conventional pulse tube refrigerator will be described with reference to the drawings.
FIG. 6 is a schematic configuration diagram of a conventional pulse tube refrigerator. FIG. 7 is a configuration diagram of the low temperature end of the prior art, FIG. 7 (a) is a view of the inside of the end body viewed from above, and FIG. 7 (b) is a side sectional view of the low temperature end.
As shown in FIG. 6, the pulse tube refrigerator 100 includes a pulse tube 110, a compressor 120, a regenerator 130, a phase controller 140, and a low temperature end 150.
[0003]
Further, the compressor 120 includes a cylinder 121 and a piston 122, the phase control unit 140 includes an inertance tube 141 and a buffer tank 142, and the low temperature end 150 includes a heat exchange unit 151 and a rectification unit 152. Yes. In such a pulse tube refrigerator 100, a flow path is formed. For example, helium is sealed as working gas (refrigerant gas) in the flow path.
[0004]
Next, the operation principle of the pulse tube refrigerator 100 will be described. When the pulse tube refrigerator 100 is operated, the piston 122 reciprocates in the cylinder 121 of the compressor 120, whereby the working gas in the cylinder 121 is compressed and expanded. Such working gas flows as a reciprocating flow from the compressor 120 through the regenerator 130, the low temperature end 150, and the pulse tube 110 to the phase control unit 140.
Further, the working gas flows in the inertance tube 141 and the buffer tank 142 of the phase control unit 140 with a pressure amplitude substantially sinusoidally.
Thereby, a phase difference is generated between the pressure change and the flow rate change of the working gas.
[0005]
When these fluid circuits are compared with electric circuits, the inertance tube 141 corresponds to the inductance, resistance, and capacitance components of the electric circuit, and the buffer tank 142 corresponds to the capacitance component.
Such a phase control unit 140 can change the phase difference of the flow rate with respect to the pressure of the working gas from −90 ° to + 90 °.
[0006]
As described above, when the pulse tube refrigerator 100 is operated, a phase difference is generated between the pressure and the flow rate of the working gas in the pulse tube 110 due to the phase control effect by the pulse tube 110 and the phase control unit 140. The work that is performed becomes the PV work in the low temperature part, and cold is generated at the low temperature end 150. This generated cold is called low-temperature PV work.
[0007]
Here, the low temperature end 150 is interposed between the regenerator 130 and the pulse tube 110 as described above, and has a substantially U-shape. When the pulse tube refrigerator 100 is in operation, the working gas sent out in the compression process of the compressor 120 flows into the pulse tube 110 at a low temperature, adiabatically expands therein, and thereby absorbs heat to the phase control unit 140. leak. Contrary to the above, in the process where the working gas passes from the phase control unit 140 through the pulse tube 110 and is refluxed to the low temperature end 150, heat is not generated or absorbed because it changes at a substantially constant volume. That is, there is no heat generation at the low temperature end 150 and only heat absorption is performed, and cold is generated.
[0008]
In this case, in order for the working gas to efficiently perform the PV work, the working gas is assumed to be as a piston (hereinafter referred to as “gas piston”) 111 partitioned in the pulse tube 110 by two fixed surfaces. It is necessary to act, and a fixed surface must be formed at least on the low temperature end 150 side. In order to form such a gas piston 111, it is indispensable to form a uniform velocity distribution without deviation in the pulse tube 110.
[0009]
Therefore, as shown in FIG. 7, a rectification unit 152 is interposed between the pulse tube 110 and the heat exchange unit 151 at the low temperature end 150. The rectifying unit 152 is formed by regularly forming a large number of holes 153 in a plate having a predetermined thickness, rectifies the working gas flowing into the pulse tube 110, and the gas piston 111 is rectified by the rectified working gas. To prevent the phase difference from being disturbed.
The prior art pulse tube refrigerator 100 is like this.
[0010]
Other conventional techniques of the pulse tube refrigerator include, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2002-235962) and Patent Document 2 (Japanese Patent Laid-Open No. 2002-349981). These prior arts relate to an invention in which the working gas flowing into the pulse tube is rectified to effectively form a gas piston in the pulse tube. Patent Document 1 discloses an invention in which a shield is provided in addition to the heat exchanger. However, Patent Document 2 discloses inventions that devise ways of installing a rectifying wire mesh.
[0011]
[Patent Document 1]
JP-A-2002-235932 (paragraph numbers 0010 to 0018, FIGS. 1 to 5)
[Patent Document 2]
JP 2002-349981 A (paragraph numbers 0010 to 0015, FIGS. 1 to 4)
[0012]
[Problems to be solved by the invention]
As one measure for making the formation of the gas piston more effective, it is conceivable to further improve the rectification function of the rectification unit. Therefore, it is necessary to increase the rectification effect as compared with the rectification unit 152 of the pulse tube refrigerator 1000 described above with reference to FIGS.
[0013]
In other conventional techniques described in Patent Documents 1 and 2, insertion of a shield, use of a fine wire mesh, and increase in the number of wire meshes are caused, causing pressure loss and unnecessary energy conversion, As a result, there was a problem that the total performance could not be increased successfully. Furthermore, since an insert such as a shield enters in addition to the heat exchanger, the whole structure tends to be large.
Therefore, there is a demand for a rectification unit that adopts a new and simple structure and enhances the rectification effect, and a pulse tube refrigerator equipped with this rectification unit.
[0014]
The present invention has been made in view of the above-mentioned problems, and its purpose is to realize both an increase in the rectification effect, a reduction in energy loss such as a pressure loss and a temperature rise, and a space saving that rectifies at a short distance. An object of the present invention is to provide a pulse tube refrigerator with greatly improved total performance.
[0015]
[Means for Solving the Problems]
In order to solve the above problems, the pulse tube refrigerator of the invention according to claim 1 of the present invention forms a flow path by connecting a compressor, a regenerator, a low temperature end, a pulse tube and a phase control unit in series, In a pulse tube refrigerator that generates cold at the low temperature end by heat exchange of the working gas flowing through the flow path,
It has a configuration in which n (n is a natural number of 1 or more) space portions and (n + 1) perforated plates are alternately arranged, and includes a rectifying portion that rectifies the working gas flowing into the pulse tube. And
[0016]
The pulse tube refrigerator of the invention according to claim 2 of the present invention is
The pulse tube refrigerator according to claim 1, wherein
The (n + 1) perforated plates are characterized in that the pore diameter of the perforated plate decreases as approaching the pulse tube.
[0017]
The pulse tube refrigerator of the invention according to claim 3 of the present invention is
In the pulse tube refrigerator according to claim 1 or 2,
It is a U-shaped return type in which the regenerator, the low temperature end, and the pulse tube are configured in a substantially U shape.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Next, a first embodiment according to the pulse tube refrigerator of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a low temperature end which is a main part of the pulse tube refrigerator of the present embodiment, FIG. 1A is a view of the inside of the end body viewed from above, and FIG. It is a sectional side view. FIG. 2 is an explanatory diagram for explaining the relationship between an attenuation factor and a resistance coefficient, FIG. 2 (a) is an attenuation factor-resistance coefficient diagram, and FIG. 2 (b) is an explanatory diagram of variables. FIG. 3 is an attenuation rate-temperature difference diagram.
[0019]
The pulse tube refrigerator of the present embodiment is almost the same as the configuration of the conventional pulse tube refrigerator described with reference to FIG. 6, and as shown in FIG. 6, the pulse tube 110, the compressor 120, and the regenerator 130. The phase control unit 140 is the same except that the low temperature end 10 shown in FIG. 1 is used instead of the low temperature end 150. Hereinafter, the configuration of the low temperature end 10 and the improvements thereof will be described. In addition, since the other structure and the freezing principle are the same, the overlapping description is abbreviate | omitted.
[0020]
As shown in FIG. 1, the low temperature end 10 of the present embodiment includes an end main body 11 and a rectifying unit 12. Further, in the end body 11, a heat exchanging portion 13 that is a space serving as a flow path for the working gas is formed.
[0021]
As shown in FIGS. 1A and 1B, the rectifying unit 12 includes two perforated plates 12a and an annular body 12b. As shown in FIGS. 1A and 1B, the perforated plate 12a is a plate having a predetermined thickness t, and has a large number of holes 12c. When such two porous plates 12a sandwich the annular body 12b, a space portion 12d is formed between them. As described above, the rectifying unit 12 is configured such that the two porous plates 12a sandwich the single space 12d.
Such a rectification unit 12 is an inlet / outlet of the working gas to / from the pulse tube 110 (see FIG. 6), and is disposed between the pulse tube 110 and the heat exchange unit 13.
[0022]
Next, a theoretical explanation of the superiority of the rectifying unit 12 will be given.
First, the disturbance rate attenuation rate A _∞ is used as an index indicating the rectifying effect, and the attenuation rate A _∞ is calculated by the following theoretical formula.
[0023]
[Expression 1]
A _∞ = (1 + α−αK) / (1 + α + K)
[0024]
Here, α is an outflow angle coefficient, and has a relationship represented by the following equation using the inflow angle θ and the outflow angle φ.
[0025]
[Expression 2]
φ = α ・ θ
[0026]
K is a resistance coefficient, and is calculated by the following equation using the differential pressure Δp before and after the resistor, the average flow velocity U, and the density ρ.
[0027]
[Equation 3]

[0028]
The above formulas (1) to (3) are theoretical formulas when the number of perforated plates is one, and the theoretical formulas for a plurality of (for example, two) perforations are not established. Therefore, an equation is calculated from the attenuation factor-resistance coefficient characteristic diagram of FIG. The empirical formula is as follows.
[0029]
[Expression 4]
| A _∞ | = 0.2164K ⁴ −1.2016K ³ + 2.5245K ² −2.5868K + 1.1782: K ≦ 2
| A _∞ | = −0.0049K ³ + 0.0628K ² −0.2509K + 0.2057: 2 ≦ K ≦ 5
However, it is a case where L / λ = 0.2 (= L / D).
[0030]
Here, L and λ are the gap between the perforated plates and the wavelength of the disturbance (corresponding to the outer diameter D in the case of a circular tube), as shown in FIG. 2 (b). The meaning of FIG. 2 (a) means that, for example, if there are perforated plates having the same resistance coefficient K = 1, the disturbance can be attenuated only to 0.4 with one sheet, but by adding two sheets, the value becomes 0.2. It can be attenuated to 13. That is, an effect of the order of the Nth power can be obtained instead of a simple N-fold effect.
[0031]
From the above, when two porous plates are used, Δp per sheet can be reduced. Therefore, the thickness t can be reduced, the aperture ratio B can be increased, and the installation space can be reduced. The degree of freedom can be greatly improved.
[0032]
In the present invention, the heat exchange capability is taken into consideration in order to provide the rectification unit also with a heat exchange function. In that case, the gas difference in the perforated plate and the temperature difference ΔT on the heating surface are considered as indices.
As shown in FIG. 2B, in the case of a perforated plate, the number of holes (diameter d) opened for a certain outer diameter D is determined when the hole diameter d and the pitch p are determined. Therefore, the aperture ratio B (= A _d / A _d ) is inevitably determined.
[0033]
Let's actually calculate. The current perforated plate is taken as a reference. The dimensions are the hole diameter d / D = 0.1, the thickness t / D = 0.5, and the aperture ratio B = 0.6. For example, the aperture ratio B is set to the same level (0.54 to 0.6). FIG. 3 shows a comparison between the attenuation rate A _∞ and the temperature difference ΔT when two sheets are used. Further, the thickness of the porous plate at this time was calculated as t / D = 0.1, and the gap between the porous plates was calculated as L / D = 0.2.
[0034]
As shown in FIG. 3, when the number of holes is increased by changing the hole diameter at the time of two sheets, the contact area with the gas increases, so that the temperature difference ΔT, which is an index of the heat exchange capacity, decreases, and at the same time the attenuation rate Will be reduced.
Conversely, the pressure loss tends to increase because the contact area increases.
[0035]
In the case of this calculation example, when the thickness is 0.05, the attenuation factor is reduced from 0.145 to 0.098 with the same pressure loss (1.00 and 1,13) as that of one sheet, and the temperature difference is reduced. The total capacity can be increased from 2.26 to 1.39.
Further, the total length (thickness) in the axial direction as the installation space can be reduced from 0.5 to 0.4 (= 0.1 × 2 + 0.2).
[0036]
In this calculation example, calculation was performed with the thickness, aperture ratio, gap, etc. of the perforated plate fixed, but any design is possible by freely setting these parameters.
[0037]
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a configuration diagram of a low temperature end which is a main part of the pulse tube refrigerator of the present embodiment, FIG. 4A is a view of the inside of the end body viewed from the upper side, and FIG. It is a sectional side view.
The pulse tube refrigerator of the present embodiment is almost the same as the configuration of the conventional pulse tube refrigerator described with reference to FIG. 6, and as shown in FIG. 6, the pulse tube 110, the compressor 120, and the regenerator 130. Although the point provided with the phase control part 140 is the same, it is different from the point which replaced with the low temperature end 150 and employ | adopted the low temperature end 20 as shown in FIG. Hereinafter, the configuration of the low temperature end 20 and the improvements thereof will be described. In addition, since the other structure and the freezing principle are the same, the overlapping description is abbreviate | omitted.
[0038]
The low temperature end 20 of the present embodiment includes an end body 21 and a rectifying unit 22 as shown in FIG. Further, in the end portion main body 21, a heat exchanging portion 23, which is a space serving as a working gas flow path, is formed.
[0039]
As shown in FIGS. 4A and 4B, the rectifying unit 22 has a large-diameter porous plate 22a on the upper side (side away from the pulse tube), an annular body 22b, and a small diameter on the lower side (side closer to the pulse tube). A perforated plate 22c is provided. As shown in FIGS. 4A and 4B, the large-diameter porous plate 22a has a large number of large-diameter hole portions 22d formed in a plate having a predetermined thickness t. As shown in FIG. 4B, the large-diameter porous plate 22a has a large number of small-diameter hole portions 22e formed in a plate having a predetermined thickness t.
[0040]
When such a large-diameter porous plate 22a and a small-diameter porous plate 22c sandwich the annular body 22b, a space 22f is formed. In this way, the rectifying unit 22 is configured such that one space 22f is sandwiched between two porous plates, a large-diameter porous plate 22a and a small-diameter porous plate 22c.
Such a rectification unit 22 is an inlet / outlet of the working gas to / from the pulse tube 110 (see FIG. 6), and is disposed between the pulse tube 110 and the heat exchange unit 23.
[0041]
As described above, in the present embodiment, the large-diameter porous plate 22a having a large pore diameter is arranged on the heat exchanging portion side, that is, on the side where the disturbance is large (folded side), and the small-diameter porous plate 22c having a small pore diameter on the pulse tube side Arranged.
This makes it possible to easily obtain a desired attenuation factor and temperature difference. For example, using the calculation example described above, a combination of d / D = 0.04 on the pulse tube side and d / D = 0.05 on the return side can form a low-temperature end having an intermediate capacity. it can.
[0042]
In the first and second embodiments, the rectifying unit is described as being two, but a combination of three or more is also possible. FIG. 5 is a side sectional view of a rectifying unit having three perforated plates.
As shown in FIG. 5A, the rectifying unit 30 includes three perforated plates 31 having the same hole diameter and two annular rings 32 each having a space 32a at the center, and the two spaces 32a and 3 You may make it have the structure arrange | positioned alternately with the perforated plate 31 of this.
Further, as shown in FIG. 5 (b), the rectifying unit 40 includes two large-diameter perforated plates 41, medium-diameter perforated plates 42, small-diameter perforated plates 43, and annular rings 44 each having a space 44a in the center. Each of them may be provided with two spaces 44 a and three large-diameter perforated plates 41, medium-diameter perforated plates 42, and small-diameter perforated plates 43.
[0043]
When generalizing the configuration of such a rectifying unit, it has a configuration in which n (n is a natural number of 1 or more) space portions and (n + 1) perforated plates are alternately arranged and arranged at the entrance and exit of the pulse tube. . In addition, at least at the entrance / exit of the pulse tube, it is necessary to be disposed in the flow path between the pulse tube and the heat exchange unit. .
[0044]
Furthermore, the same hole diameter (first embodiment) or a larger diameter on the side away from the pulse tube (heat exchange section side) and a smaller diameter on the pulse tube side (second embodiment) Configure.
If the various rectification units comply with such a standard, the rectification effect can be enhanced.
[0045]
【The invention's effect】
As described above, according to the present invention, the rectifying effect is increased, the energy loss such as pressure loss and temperature rise is reduced, and the space saving by rectifying at a short distance is realized, and the total performance is greatly improved. An improved pulse tube refrigerator can be provided.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a low-temperature end that is a main part of a pulse tube refrigerator according to a first embodiment of the present invention, and FIG. ) Is a side sectional view of the low temperature end.
2A and 2B are explanatory diagrams for explaining a relationship between an attenuation rate and a resistance coefficient. FIG. 2A is an attenuation rate-resistance coefficient diagram, and FIG. 2B is an explanatory diagram of variables.
FIG. 3 is an attenuation rate-temperature difference diagram.
FIG. 4 is a configuration diagram of a low-temperature end that is a main part of a pulse tube refrigerator according to a second embodiment of the present invention, and FIG. ) Is a side sectional view of the low temperature end.
FIG. 5 is a side sectional view of a rectifying unit having three perforated plates.
FIG. 6 is a schematic configuration diagram of a conventional pulse tube refrigerator.
7A and 7B are configuration diagrams of the low temperature end of the prior art, in which FIG. 7A is a view of the inside of the end body viewed from above, and FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10: Low temperature end 11: End main part 12: Rectification part 12a: Perforated plate 12b: Ring body 12c: Hole part 12d: Space part 13: Heat exchange part 20: Low temperature end 21: End main part 22: Rectification part 22a: Large Diameter porous plate 22b: Ring body 22c: Small diameter porous plate 22d: Large diameter hole portion 22e: Small diameter hole portion 22f: Space portion 23: Heat exchange portion 30: Rectification portion 31: Porous plate 32: Ring body 32a: Space portion 40: Rectifier 41: Large-diameter perforated plate 42: Medium-diameter perforated plate 43: Small-diameter perforated plate 44: Ring body 44a: Space portion 100: Pulse tube refrigerator 110: Pulse tube 111: Gas piston 120: Compressor 121: Cylinder 122: Piston 130: Regenerator 140: Phase control unit 141: Inertance tube 142: Buffer tank 150: Low temperature end 151: Heat exchange unit 152: Rectification unit 153: Hole

Claims (3)

In a pulse tube refrigerator that connects a compressor, a regenerator, a low temperature end, a pulse tube, and a phase control unit in series to form a flow path, and generates cold at the low temperature end by heat exchange of the working gas flowing through the flow path,
It has a configuration in which n (n is a natural number of 1 or more) space portions and (n + 1) perforated plates are alternately arranged, and includes a rectifying portion that rectifies the working gas flowing into the pulse tube. And pulse tube refrigerator. The pulse tube refrigerator according to claim 1, wherein
The (n + 1) perforated plate is a pulse tube refrigerator characterized in that the pore diameter of the perforated plate becomes smaller as it approaches the pulse tube. In the pulse tube refrigerator according to claim 1 or 2,
A pulse tube refrigerator characterized by being a U-shaped return type in which a regenerator, a low temperature end, and a pulse tube are formed in a substantially U-shape.

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