JPH046354A - Expansion device of stirling cycle refrigerating machine - Google Patents

Abstract

PURPOSE:To enhance the temperature gradient on the base end side to improve the performance of regenerator by a method wherein a heat station which covers a cold head at the tip of a cylinder is extended toward the base end side of the cylinder, and a range on the low temperature side of the regenerator, within which gas goes into and out from a gas expansion chamber, is cooled and kept at a constant cryogenic temperature level by the cold station. CONSTITUTION:When coldness of a cryogenic temperature level is generated by a cold head 3, the cold head 3 is provided with a heat station 17. Gas goes into and out from an expansion chamber 13 within a range A with the reciprocating motion of a displacer 5 in a regenerator 9, and the heat station 17 is extended toward the base end of the cylinder 2 and up to a position to which the range A moves at the end of stroke on the base end side of the cylinder 2.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an expander for a Stirling refrigerator that expands refrigerant gas in an expansion chamber in a cylinder by reciprocating a displacer to generate cryogenic cold. , relates to the structure of a regenerator (regenerative heat exchanger) housed in a displacer.

(Prior art) This type of Stirling refrigerator, as shown in Fig. 7,
This is a combination of a near-motor type compressor (a) that pressurizes refrigerant gas at a predetermined period, and an expander (k) that expands the refrigerant gas pressurized by the compressor (a).

The compressor (a) includes a sealed cylinder (c) formed in a casing (b), a piston (e) fitted into the cylinder (c) so as to be able to reciprocate, and the piston ( e
), a coil (i) wound around the bobbin (h), and a magnet (
g), a near motor (f) for reciprocating the piston (e), and a piston spring (j) for elastically supporting the piston (e) in a reciprocating manner;
) by applying an alternating current of a predetermined frequency to the piston (e
) is reciprocated within the cylinder (c), and the cylinder (c)
It is configured to generate gas pressure at a predetermined period in the compression chamber (d) at the inner light end.

On the other hand, the expander (k) has a cylinder (L), and the inner space of the cylinder (Ill) is divided into an expansion chamber (m) on the distal end side and a working chamber (n) on the proximal end side. A free displacer (0) partitioned into the spacer is inserted so as to be reciprocally movable. This displacer (o) has a built-in regenerator (01) that communicates with the expansion chamber (m) and the working chamber (n) through communication holes (o2) and (03), respectively.

Also, within the working chamber (n) is a displacer spring (p) that elastically supports the displacer (o) in a reciprocating manner.
is installed. (S) is a vacuum container to which the expander (k) is attached, and its flange (Sl) is hermetically joined to the flange (r) at the base end of the cylinder (N). The working chamber (n) is connected to the compression chamber (d) of the compressor (a) via a connecting pipe (q), and the displacer (0) is By reciprocating the refrigerant gas, the refrigerant gas is expanded in the expansion chamber (m) and cold is generated in the cold head at the tip of the cylinder (g).
for Cryogenic 5 sensors,
NASA ConferencePublicati
on 22g7 etc.).

(Problem to be solved by the invention) By the way, in the expander (k) of this Stirling refrigerator, as shown in FIG. 2, the cylinder CD of the regenerator (01) built in the displacer (0) is While the side end is at room temperature (for example, 50"C-323K), the tip is at a cryogenic level of about 70"C.The larger the temperature gradient between the room temperature end and the low temperature end, the more desirable the regenerator is. (ol) efficiency is improved.Increasing this temperature gradient can be achieved, for example, by increasing the heat transfer area of the regenerator (ol), but on the other hand, the pressure loss of the regenerator (ol) increases, etc. This may not be an effective solution as it may lead to other problems.

The purpose of the present invention is to improve the temperature gradient of the regenerator, thereby increasing the temperature gradient on the proximal side without causing new problems, and improving the performance of the regenerator. It's about letting people know.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the invention according to claim (1) extends the heat station that covers the cold head at the tip of the cylinder toward the base end of the cylinder, This heat station cools and maintains the region at the cold end of the regenerator where gas flows back and forth to the expansion chamber at a constant cryogenic level.

That is, as shown in FIG. 1, the present invention includes a cylinder (2) having a cold head (3) at its tip, and a cylinder (2) that is elastically supported within the cylinder (2) so as to be able to reciprocate.
2) Inside the proximal side working chamber (12) and distal side expansion chamber (
13), and a regenerator (9) built into the displacer (5) and communicating with the working chamber (12) and the expansion chamber (13). The expansion chamber (1
3) is based on an expander of a Stirling refrigerator that generates cryogenic cold in the cold head (3) by expanding the refrigerant gas.

The feature is that the cold head (3) is provided with a heat station (17), and the heat station (17) is connected to the expansion chamber (13) as the displacer (5) reciprocates in the regenerator (9). The range (A) in which gas flows back and forth extends toward the base end of the cylinder (2) to a position where the displacer (5) moves at the stroke end of the base end of the cylinder (2).

Moreover, the solving means of the invention according to claim 2 differs in the matrix characteristics on the low temperature side and the normal temperature side in the regenerator, and the matrix on the low temperature side has a higher thermal conductivity than that on the normal temperature side.

Specifically, as shown in FIG. 3, the present invention provides a large number of matrices (10), (11) filled in the displacer (5) for the expander based on the above premise.
On the distal end side of the regenerator (9), a proximal matrix made of, for example, stainless steel is placed in the range (A) where gas flows back and forth between the expansion chamber (13) and the displacer (5) as the displacer (5) reciprocates. A matrix (10) made of copper or the like having a higher thermal conductivity than (11) is filled.

Furthermore, in the invention according to claim (3), as shown in FIG.
In the invention according to claim (4), a matrix accommodation space (7b) is formed in the space (7b), and a matrix (1o) made of copper or the like having a high thermal conductivity similar to that described above is provided in the space (7b). As shown in the figure, a large number of metal meshes (10a) in which the regenerator (9) is filled in a displacer (5) in a layered manner (
10b), and an expansion chamber (
13) A mesh (10b) coarser than the base end side is filled in the area (A) where gas flows back and forth between the base end side and the base end side.

Further, in the invention according to claim (5), as shown in FIG. A coarse metal mesh (10b) is accommodated in the space (7b).

Note that when the displacer (5) moves forward from the neutral position (M) toward the distal end by half the stroke, the expansion chamber (
13) enters the regenerator (9), and conversely, when the displacer (5) retreats from the neutral position (M) toward the proximal end of the cylinder (2) by half the stroke during the double movement, the regenerator ( 9) Gas comes out from inside and expands into the expansion chamber (1
3) Enter. For this reason, the above “Regenerator (9)
As the displacer (5) reciprocates, the expansion chamber (
In other words, the range (A) in which gas flows back and forth between the regenerator (9) and the regenerator (9) can be said to be the range approximately equal to the stroke of the proximal head displacer (5).

(Function) With the above configuration, in the invention according to claim (1), when the expander is operated, the displacer (5) in the cylinder (2)
), the gas expands in the expansion chamber (13), and the cold head (3) at the tip of the cylinder (2) is cooled to an extremely low temperature level. Station (17) is also cooled. This heat station (17) is equipped with a regenerator (9).
), the range (A) in which gas flows back and forth between the expansion chamber (13) and the expansion chamber (13) as the displacer (5) reciprocates extends to the position where the displacer (5) moves at the proximal stroke end of the cylinder (2). Therefore, the gas flow range (A) is constantly cooled by this heat station (17) regardless of the reciprocation of the displacer (5), and the gas in that range (A) is kept at an extremely low temperature level. .

Therefore, in the regenerator (9), the above gas flow range (
There is a temperature gradient from normal temperature to a cryogenic level in the proximal portion except for A), and the temperature gradient becomes large, thereby improving the performance of the regenerator (9).

Furthermore, since this large temperature gradient occurs in a portion other than the gas flow range (A) at the tip of the beam generator (9), the range is relatively short and the pressure loss does not increase significantly.

In the invention according to claim Z, the gas flow range (A) on the tip side of the regenerator (9) is filled with a matrix (10) made of copper or the like having high thermal conductivity, and the remaining room temperature side part is filled with a thermally conductive matrix (10). Since the proximal matrix (11) made of stainless steel or the like having a low index is filled, the gas temperature tends to decrease, thereby increasing the temperature gradient. range(
Since matrix (10) in A) has high thermal conductivity,
The temperature of the matrix (10) is kept cool at cryogenic levels. Therefore, the same effects as above can be obtained.

Further, in the invention according to claim (3), the displacer (
5) A matrix (1
0), there is an advantage that the temperature at the tip of the regenerator (9) can be more stably maintained at an extremely low temperature level.

In the invention according to claim (4), the mesh (10b) filled in the gas flow range (A) at the tip of the regenerator (9)
) is rough, so the heat exchange efficiency with that gas is low. on the other hand,
Since the remaining mesh (10a) is fine, it has good heat exchange efficiency with the gas, and the gas is easily cooled. Therefore, the same effects as above can be obtained.

Further, in the invention according to claim (5), the displacer (
5) Matrix accommodation space (7b) of the head (7) at the tip
) is accommodated in the rough metal mesh (10b), so it is possible to achieve the same effect as the invention according to claim (3) above.

(First example) Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, (1) shows an expander of a free displacer type Stirling refrigerator according to the first embodiment of the present invention, and this expander (1) is connected to a near motor compressor (31) and a coupling pipe (30). connected. The above compressor (
31) has the same configuration as that explained in the section of "Prior Art" (see FIG. 7), so detailed explanation will be omitted here.

The expander (1) includes a bottomed cylindrical cylinder (2) with a closed end and a mounting flange (18) externally fitted to the outer periphery of the proximal end of the cylinder (2). . The proximal opening of the cylinder (2) is hermetically closed by a closing member (4), and the distal end of the cylinder (2) is a cold head (3). A free displacer (5) is fitted into the cylinder (2) so as to be able to reciprocate, and this displacer (5) separates the inside of the cylinder (2) from the working chamber (12) on the proximal end of the cylinder (2) and the distal end. Side expansion chamber (1
3) It is divided into two parts.

The displacer (5) has a case (8) in which the openings at both ends of a cylindrical body made of a thin metal such as stainless steel are hermetically closed by heads (6) and (7), respectively.
) and a beam generator (9) inside this case (8).
) (regenerative heat exchanger) is housed. This regenerator (9) has a large number of copper disk-shaped meshes (10), (10), .
... are stacked and filled in the case (8) in its length direction (axial direction).

The above heads (6) and (7) each have a case (8).
) A communication hole (6g) that communicates the internal pressure generator (9) with the expansion chamber (13) and the working chamber (12).

(7a) is opened, and when the low-temperature refrigerant gas expanded in the expansion chamber (13) heads toward the working chamber (12), the regenerator (9) is cooled by the refrigerant gas, storing cold heat therein, and vice versa. When the refrigerant gas at room temperature goes from the working chamber (12) to the expansion chamber (13), the regenerator (9
) to cool the gas.

Further, in the working chamber (12), there is a displacer (5).
) is provided with a displacer spring (16) made of a coil spring that elastically supports the reciprocating movement of the displacer spring (16). This spring (16) is connected to the distal end side (
Spring stopper (4a) formed on the displacer (5) side)
and a spring stopper (6b) formed at the base end of the normal temperature side head (6) in the case (8) of the displacer (5), and this spring (16)
A predetermined frequency determined by the spring constant of the compressor (31)
The reciprocating motion mode of the displacer (5) is determined by the period of gas pressure fluctuation.

On the other hand, the mounting flange (18) is for attaching the expander (1) to the vacuum container (19), and the mounting flange (18) is for attaching the expander (1) to the vacuum container (19).
2) A boss part (18a) externally fitted to the base end, and a flange part (18a) formed at the distal end of the cylinder (2).
b), and the cylinder (2) of the flange part (18b).
) An annular fitting groove (18c) for fitting the seal ring (20) is concentrically formed on the side surface of the tip. The vacuum container (19) has a bottomed cylindrical shape into which the cylinder (2) can be inserted with a certain gap, and the open end thereof has a flange having the same diameter as the flange portion (18b) of the mounting flange (18). portion (19a) is formed, and both flange portions (
18b) and (19a) in close contact with each other, and vacuum container (1
9) The inside is sealed.

A gas inlet (4b) communicating with the working chamber (12) in the cylinder (2) is formed through the center of the closing member (4) along the cylinder axis direction, and the gas inlet (4b)
is a coupling pipe (30) connected to the compressor (31).
are connected in a sealed manner, and the refrigerant gas pressure from the compressor (31) causes the displacer (5) to reciprocate and expand the refrigerant gas in the expansion chamber (13). It is designed to generate cold in the head (3).

Furthermore, the cold head (3) at the tip of the cylinder (2) is
) is integrally attached with a cap-shaped heat station (17) capable of transmitting heat. As the displacer (5) reciprocates, gas in the expansion chamber (13) enters and exits the regenerator (9), and gas flows back and forth between the regenerator (9) and the expansion chamber (13).
As a feature of the present invention, the heat station (17)
When the displacer (5) is at the stroke end on the base end side of the cylinder (2), the regenerator (9)
) Extends toward the base end of the cylinder (2) to a position where the end portion on the base end side of the cylinder is positioned in the gas flow range (A) at the tip (indicated by the dashed diagonal line in the figure).

In addition, (14) is the normal temperature side head (
6) A normal temperature side seal placed around the head (15) is a low temperature side seal similarly placed around the low temperature side head (7).

Next, the operation of the above embodiment will be explained.

As the refrigerator operates, the piston reciprocates within the cylinder due to the operation of the linear motor in the compressor (31), and the volume of the compression chamber increases or decreases due to the reciprocating movement of the piston, and the refrigerant inside the compression chamber changes at a predetermined period. Pressure is applied to generate pressure waves with a predetermined period. Since this compression chamber communicates with the working chamber (12) of the expander (1) via the coupling pipe (30),
When the pressure in the compression chamber becomes high, pressurized refrigerant gas is supplied to the working chamber (12) and the pressure in the working chamber (12) increases. Due to this pressure increase, the working chamber (12)
and the expansion chamber (13), and this pressure difference causes the displacer (5) to move to the neutral position W (M
), the displacer spring (16) moves toward the distal end of the cylinder (2) while extending, and the pressure in the expansion chamber (13) increases. This working chamber (12) is connected to the expansion chamber (13) via a glue generator (9) in the displacer (5).
), so in the next step, the gas passes through the regenerator (9) and flows into the expansion chamber (13) while being cooled, and the differential pressure between the two chambers (13) and (12) disappears, causing the displacer ( 5) moves toward the proximal end of the cylinder (2) due to the contraction force of the spring (16) and returns to its original neutral position (M).
Return to Immediately thereafter, the piston of the compressor (31) retreats and the pressure in the compression chamber decreases. For this reason, the working chamber (
The refrigerant gas in the working chamber (12) returns to the compressor (31) via the coupling pipe (30), and the pressure in the working chamber (12) increases to the expansion chamber (12).
3). This working chamber (12) and expansion chamber (1
3), the displacer (5) moves from the neutral position (M) toward the base end of the cylinder (2) while contracting the displacer spring (16), causing the refrigerant in the expansion chamber (13) to Gas expands adiabatically and generates cold. In the next step, the expanded gas passes from the expansion chamber (13) into the displacer (5) and into the regenerator (9).
flows toward the working chamber (12) while imparting cold energy to the air, the differential pressure between the two chambers (12) and (1B) disappears, and the displacer (5) moves toward the tip of the cylinder (2) due to the expansion force of the spring (16). Move and return to original position. One cycle is completed by the above, and by repeating the same cycle, the cold head (3) at the tip of the cylinder (2)
and an integral heat station (17) are gradually cooled to cryogenic levels.

The heat station (17) has a displacer (
5) is at the stroke end on the base end side of the cylinder (2), the expansion chamber (13) at the tip of the regenerator (9)
Since the gas flow range (A) extends toward the proximal end of the cylinder (2) to the position where the gas flow range (A) is located, the gas flow range (A) is always kept at a cryogenic level of heat regardless of the reciprocating movement of the displacer (5). Cooled by station (17), the gas temperature is kept at cryogenic levels. Therefore,
As shown by the solid line in Fig. 2, in the regenerator (9), a temperature gradient occurs from the normal temperature part to the low temperature part in areas other than the gas flow range (A) where the cryogenic level is reached, and the temperature gradient becomes larger. , thus improving the performance of the regenerator (9).

Further, since a large temperature gradient is generated in a short range excluding the gas flow range (A) at the tip of the regenerator (9), pressure loss does not increase.

(Second Embodiment) FIG. 3 shows the second embodiment. In each of the following embodiments,
The same parts as in FIG. 1 are denoted by the same reference numerals and detailed explanation thereof is omitted), and the structure of the regenerator (9) is changed.

That is, in this embodiment, the heat station (1) provided in the cold head (3) at the tip of the cylinder (2)
7') is different from the above embodiment and has a normal length. Instead, there are two types of regenerator matrices filled in the case (8), and the regenerator (
9), a large number of copper meshes (10), (10), etc. with high thermal conductivity are stacked in the area (A) where gas flows back and forth between the expansion chamber (13) and the expansion chamber (13). On the other hand, the remaining part on the room temperature side is filled with a large number of stainless steel meshes (11), (11), etc., which have poor thermal conductivity and a large heat transfer area with the gas, in a stacked state. has been done.

Therefore, in this embodiment, since the thermal conductivity of the copper meshes (10), (10), etc. filled in the gas flow range (A) on the tip side of the regenerator (9) is high, the temperature thereof is It is kept cooled to cryogenic levels. On the other hand, the stainless steel meshes (11), (11), . This allows stainless steel mesh (11
), (11), . . . , a temperature gradient is created in the filled portion, and the temperature gradient can be increased, so that the same effect as in the above embodiment can be obtained.

(Third Embodiment) Figure 4 shows a third embodiment, in which a copper mesh (10), (
10), . . . are also filled in the distal head (7') of the displacer (5).

That is, the low temperature side head (7') of the displacer (5)
) is composed of a circular box-shaped member with a bottom that opens on the proximal end side, and a communicating hole (7a/ ) is formed in the center of the bottom wall. A matrix accommodation space (7b') is provided inside the head (7'), and this space (7b')
Also, a large number of disc-shaped copper meshes (10), (10), etc., similar to those at the tip of the case (8), are stacked and filled.

In this embodiment, a copper mesh (10) with high thermal conductivity is also installed on the head (7') on the distal end side of the displacer (5).
(10), . . . are accommodated, the temperature at the tip of the regenerator (9) can be more stably maintained at an extremely low temperature level compared to a normal head structure.

(Fourth Embodiment) FIG. 5 shows a fourth embodiment, in which all the regenerator matrices are the same, for example, copper meshes (10) (10),
Instead, the roughness of the mesh was changed between the distal end and the proximal end.

In other words, in the gas flow range (A) between the distal end side of the regenerator (9) and the expansion chamber (13), there are many coarse copper meshes (10b) with small mesh numbers, (1
0b), . . . are filled, while the remaining room temperature side portion is filled with fine meshes (10a), (10a), . . . which are made of copper but have larger mesh numbers.

Therefore, if you do this, regenerator (9)
The mesh (10
b), (10b), ... are rough, so the heat exchange efficiency with the gas becomes low. Meanwhile, the remaining mesh (10a
), (10a), ... are fine, so they have good heat exchange efficiency with the gas, and the gas is easily cooled. Therefore, the same effects as in the second embodiment can be obtained.

(Fifth Embodiment) Furthermore, as shown in FIG. 6, a matrix accommodation space (7b') is provided in the head (7') at the tip of the displacer (5).
may be formed and the coarse copper meshes (10b), (10b), .

(Effect of the invention) As described above, according to the invention according to claim (1), in the expander of a Stirling refrigerator, the heat station covering the cold head at the tip of the cylinder is connected to the expansion chamber in the regenerator. By extending the gas flow range toward the cylinder base end to the expansion chamber in the regenerator located at the stroke end of the displacer on the cylinder base end side, the gas flow range is constantly cooled regardless of the reciprocating movement of the displacer. , the gas can be kept at cryogenic levels, increasing the temperature gradient from room temperature to cryogenic levels in the regenerator without increasing pressure loss, and improving regenerator efficiency. .

Further, in the invention according to claims (2 and (3)), the matrix materials on the low temperature side and the room temperature side of the regenerator are made different, and the matrix on the low temperature side uses a material having a higher thermal conductivity than that on the room temperature side. Claim (4) and (
In the invention according to 5), a coarser metal mesh is used on the low temperature side than on the room temperature side. Therefore, according to these inventions, heat exchange between the matrix on the proximal end side of the regenerator and the gas is performed smoothly, the temperature of the gas is easily lowered, and the temperature gradient can be increased. It is difficult to exchange heat with the gas, and the temperature of the matrix is kept cooled to a cryogenic level, so a similar effect can be obtained.

[Brief explanation of drawings]

1 and 2 show a first embodiment of the present invention, with FIG. 1 being an enlarged sectional view of the expander, and FIG. 2 being a diagram showing the temperature distribution of the beam generator. 3 to 6 are sectional views of main parts of expanders showing second to fifth embodiments of the present invention, respectively. FIG. 7 is a sectional view showing a conventional example of a Stirling refrigerator. (1)...Expander (2)...Cylinder (5)...Displacer (7), (7')...Head (7b')...Matrix accommodation space (9)... Regenerator (10)...Copper mesh (matrix) (10a
)... Fine copper mesh (matrix) (10b)... Coarse copper mesh (matrix) (11)... Stainless steel mesh (matrix) (12)... Working chamber (13)... Expansion Chamber (17)...Heat station (31)...Compressor (1)...Expander (]2)...Working chamber...Expansion chamber Heat station...Compressor Fig. 1 Fig. 2 Figure 5 Figure 4 Figure 7 Ward

Claims (5)

[Claims] (1) A cylinder with a cold head (3) at the tip (
2), and a displacer (2) which is elastically supported within the cylinder (2) so as to be able to reciprocate and defines a working chamber (12) on the proximal side and an expansion chamber (13) on the distal side within the cylinder (2).
5), and a regenerator (9) that is built into the displacer (5) and communicates with the working chamber (12) and the expansion chamber (13). In the expansion machine of the Stirling refrigerator, the cold head (3) is equipped with a heat station (1
7), and in the heat station (17), the range (A) where gas flows back and forth between the expansion chamber (13) and the displacer (5) as the displacer (5) reciprocates in the regenerator (9) is the displacer (17). 5) Move the cylinder (2) to the position where it moves to the proximal end of the stroke.
2) An expander for a Stirling refrigerator characterized by extending toward the proximal end. (2) A cylinder with a cold head (3) at the tip (
2), and a displacer (2) which is elastically supported within the cylinder (2) so as to be able to reciprocate and defines a working chamber (12) on the proximal side and an expansion chamber (13) on the distal side within the cylinder (2).
5), and a regenerator (9) that is built into the displacer (5) and communicates with the working chamber (12) and the expansion chamber (13). In the Stirling refrigerator expander, which generates cryogenic cold in the cold head (3) by expanding the refrigerant gas in step 13), the regenerator (9) is filled into the displacer (5). A range (A) where gas flows back and forth between the expansion chamber (13) and the expansion chamber (13) as the displacer (5) reciprocates on the tip side of the regenerator (9). An expander for a Stirling refrigerator, characterized in that the matrix (10) is filled with a matrix (10) having a higher thermal conductivity than the base end side. (3) Displacer (5) Head (7) that closes the tip
) A matrix accommodation space (7b) is formed in the Stirling refrigerator according to claim (2), wherein the space (7b) also accommodates a matrix (10) having a high thermal conductivity. Machine. (4) Cylinder with cold head (3) at the tip (
2), and a displacer (2) which is elastically supported within the cylinder (2) so as to be able to reciprocate and defines a working chamber (12) on the proximal side and an expansion chamber (13) on the distal side within the cylinder (2).
5), and a regenerator (9) that is built into the displacer (5) and communicates with the working chamber (12) and the expansion chamber (13). In the Stirling refrigerator expander, which generates cryogenic cold in the cold head (3) by expanding the refrigerant gas in step 13), the regenerator (9) has a layered structure inside the displacer (5). A large number of metal meshes (10a) filled with
10b), and the expansion chamber (13
An expander for a Stirling refrigerator, characterized in that a region (A) where gas flows back and forth between the two is filled with a mesh (10b) coarser than the base end side. (5) Displacer (5) Head (7) that closes the tip
The expander for a Stirling refrigerator according to claim 4, wherein a matrix accommodation space (7b) is formed in the space (7b), and a coarse mesh (10b) is also accommodated in the space (7b).