JP2737706B2 - Refrigerator expansion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expansion device for a refrigerator, which obtains a cryogenic temperature by expanding a refrigerant by reciprocating a displacer in a cylinder.

[0002]

2. Description of the Related Art Conventionally, a reverse Stirling cycle, a Gifford McMahon cycle and the like have been known as a refrigeration cycle using a gas such as helium, hydrogen and nitrogen which is hardly liquefied at a low temperature as a refrigerant. FIG. 14 shows a configuration example of a refrigerator using an inverse Stirling cycle. The refrigerator is provided with an expansion cylinder 1 and a compression cylinder 2, and has a displacer (expansion piston) 3 and a compression piston 4 that reciprocate inside each other.

[0003] The end face of the expansion cylinder 1 is hermetically sealed by a cooling section 6 to which a cooled body 5 is attached. The expansion device includes the expansion cylinder 1, the displacer 3, and the cooling unit 6. In the displacer 3, a regenerator 7 having a refrigerant passage is provided.
The expansion cylinder 1 and the compression cylinder 2 are connected by a pipe 8, and the refrigerant moves between the expansion space 11 and the compression space 11 ′ via the regenerator 7 and the communication passages 9 and 10 in the displacer 3. The pipe 8 radiates the refrigerant compressed from its outer periphery. Further, a radiator for dissipating the refrigerant compression heat may be specially provided in the pipe 8. Further, in order to prevent leakage of the refrigerant, seal members 12 are provided on the outer periphery of the displacer 3 and the compression piston 4, respectively.

[0004] In such a refrigerator, it is important to efficiently remove heat from the cooled object 5 attached to the cooling section 6. FIG. 15 shows a conventional example of an expansion device for improving the effect of absorbing heat from the cooled object 5. The expansion device shown in FIG. 15 is described in Japanese Patent Application Laid-Open No. 6-34216. In this expansion device, a refrigerant communication passage 10 provided at the top of the displacer 3 is inclined obliquely near the inner surface of the end of the expansion cylinder 1. It is open.

[0005] With such a configuration, the refrigerant ejected from the communication passage 10 collides against the inner surface of the end of the expansion cylinder 1, and a turbulent flow having a good heat transfer coefficient can be obtained and the cooling section 6 can be cooled well. Like that. The expansion cylinder 1
Of the cooling section 6 and the expansion cylinder 1 are made of a material having a high thermal conductivity by making the end portion of the cooling portion 6 and the thick end portion of the expansion cylinder 1 near the middle position between the top and bottom dead centers of the displacer 3 from the end surface thereof. Has reduced thermal resistance. Further, grooves 13 and 14 are provided on the inner surfaces of the cooling section 6 and the thick end of the expansion cylinder 1 to increase the surface area for heat conduction with the refrigerant.

[0006]

By the way, in order to improve the refrigeration efficiency of the refrigerator, it is necessary to reduce the thermal resistance of the cooling section 6 and the expansion cylinder 1 interposed between the cooled object 5 and the refrigerant. Important, and for this reason,
While both the above 1 and 6 are made of a material having high thermal conductivity,
Although its shape is made thick, the heat transfer coefficient on the inner surface of the cooling section 6 and the expansion cylinder 1 which is in direct contact with the refrigerant is very small compared to the thermal conductivity of the cooling section and the expansion cylinder. There is a limit to the decrease. Also, grooves are provided on the inner surfaces of the cooling section 6 and the thick end of the expansion cylinder 1, but this also has a limit on the amount of increase in the surface area.
In the conventional example, the refrigeration efficiency cannot be sufficiently improved.

[0007] In view of the above, it is an object of the present invention to provide a refrigerating machine expansion device capable of effectively improving the refrigerating efficiency.

[0008]

In order to achieve the above object, the present invention employs the following technical means. According to the first aspect of the present invention, the cooling section (6) for cooling the object to be cooled, the expansion cylinder (1) whose end is hermetically sealed by the cooling section (6), and the inside of the expansion cylinder (1). And a displacer (3) forming an expansion space (11) from which the refrigerant is ejected , the cooling unit (6) or the expansion cylinder (1). the inner surface, said expansion space (11) the heat transfer accelerating members projecting are disposed, the heat transfer promotion body is also one
Is characterized by comprising a plurality of laminated nets (15) .

In the invention according to claim 2, the expansion space (1
The heat transfer enhancer protruding from 1) is replaced by a number of pins.
It is characterized by comprising a fin (18) in a shape of a circle.

According to the third aspect of the present invention, the expansion space is provided.
The heat transfer enhancer protrudingly arranged in (11) is made of a foam material (1).
9). Claim 4
In the described invention, the protruding arrangement is provided in the expansion space (11).
A heat transfer enhancer composed of a large number of microparticles (20)
It is characterized by.

Further , in the invention according to claim 5, the cooling unit is provided.
(6) or an expansion space on the inner surface of the expansion cylinder (1).
The heat transfer enhancers (15, 18, 19, 2) protruding to (11)
0) is arranged, and a ring is arranged around the outer periphery of the displacer (3).
-Shaped protrusion (3A), and a gap is provided outside the entire heat transfer promoting body.
A gap (16) is formed, and a ring-shaped protrusion is formed in the gap (16).
Part (3A) can be inserted, and the displacer (3)
The communication passage (1) for ejecting the refrigerant is provided inside the protruding portion (3A).
0). Claim 6
In the invention described above, the cooling unit (6) or the expansion cylinder (1)
On the inner surface of the heat transfer enhancer (1) projecting into the expansion space (11).
5, 18, 19, 20) and displacer
(3) A cylindrical projection (3B) is provided at the center of the
A columnar protrusion (3B) can be inserted into the center of the entire accelerator
The cylindrical projection of the displacer (3)
(3B) having a communication passage (10) for jetting refrigerant.
Features.

In the invention according to claim 7 , the cooling section (6) for cooling the object to be cooled, the expansion cylinder (1) whose end is hermetically sealed by the cooling section (6), and the expansion cylinder (6). 1) A refrigerating machine having a displacer (3) reciprocally fitted in the reciprocating chamber and forming an expansion space (11) from which a refrigerant is ejected. Alternatively, on the inner surface of the expansion cylinder (1), a number of minute holes (2
1) is provided.

The reference numerals in the parentheses of the above means indicate the correspondence with the concrete means described in the embodiments described later.

[0014]

According to the first to sixth aspects of the present invention, as described above, since the heat transfer promoting body is disposed in a protruding manner on the inner surface of the cooling unit or the expansion cylinder, the expansion space is provided. Since the refrigerant ejected from the displacer collides with the heat transfer promoting body and the refrigerant is well stirred in the expansion space, the heat transfer coefficient between the refrigerant and the cooling unit and the expansion cylinder is increased, and the refrigeration efficiency of the refrigerator is reduced. improves.

In addition, the arrangement of the heat transfer enhancer can increase the heat transfer surface area of the expansion space, so that the refrigeration efficiency can be effectively improved in combination with the improvement of the heat transfer coefficient. Especially,
As in the first aspect of the present invention, the heat transfer enhancer is one sheet.
Or comprised of a plurality of meshes, or claimed
As in the invention described in 2, it is composed of many pin-shaped fins
Or a foamed material as described in claim 3
Or as in the invention of claim 4,
By using a large number of fine particles, the heat transfer surface area of the expansion space can be dramatically increased, and the refrigeration efficiency can be increased.

According to the invention described in claim 5 , the display is
A ring-shaped projection is provided on the outer periphery of the racer,
A gap is formed on the outside of the whole, and this gap has a ring-shaped protrusion.
Can be inserted, the volume of the expansion space when the displacer is at the top dead center can be reduced to the minimum necessary. Can be enhanced. At the same time, the entire periphery of the heat transfer enhancer is
It means that surround the ring-shaped protruding portion, the ring-shaped protrusion
The refrigerant that has been ejected from the communication passage located inside and has collided with the heat transfer enhancer is agitated without escaping to the lower side of the expansion cylinder, and the refrigeration efficiency is further improved.

Further, in the invention according to claim 6 , the display is
Equipped with a cylindrical projection at the center of the racer,
Since the columnar protrusion can be inserted into the center of the body, the volume of the expansion space at the time of the top dead center of the displacer can be reduced to a necessary minimum, and the refrigeration efficiency can be improved. In the invention according to claim 7 , by arranging a large number of minute holes on the inner surface of the cooling unit or the expansion cylinder,
The heat transfer surface area of the expansion space is dramatically increased, and the refrigeration efficiency of the refrigerator can be improved.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. (First Embodiment) FIG. 1 is a cross-sectional view of a main part of a first embodiment of an expansion device for a refrigerator according to the present invention. The entire configuration of the refrigerator is the same as that of the prior art shown in FIG. The description will be omitted, and the inflation device which is a feature of the present invention will be described in detail below. The cooling section 6 for cooling a cooled object (not shown) and the thick end of the expansion cylinder 1 are made of a material having a high thermal conductivity, for example, a metal such as copper. It is preferable that the thin portion (the portion below the thick end) of the expansion cylinder 1 is made of a material having low thermal conductivity, for example, a metal such as stainless steel, and is integrally joined to the thick end.

The cooling section 6 is joined to the end face of the thick end of the expansion cylinder 1 by brazing or the like so as to hermetically seal the expansion cylinder 1. The displacer 3 is provided inside the expansion cylinder 1 so as to be able to reciprocate and serves as an expansion piston, and a regenerator 7 is provided therein. The regenerator 7 cools the cooling heat of the refrigerant, and has a refrigerant passage (not shown) through which the refrigerant flows.

An expansion space 11 is formed by the upper end surface of the displacer 3, the cooling section 6 and the expansion cylinder 1, and a plurality of communication passages 10 for jetting refrigerant into the expansion space 11 are provided on the upper end surface of the displacer 3. It opens diagonally. That is, the communication passage 10 is arranged obliquely toward the inner surface near the end of the expansion cylinder 1 so that the refrigerant collides with the inner surface near the end of the expansion cylinder 1.

In the expansion space 11, a net 15 is provided so as to protrude downward from the inner surface of the cooling unit 6 (toward the upper end surface of the displacer 3). The mesh 15 constitutes a heat transfer enhancer that promotes heat transfer between the refrigerant and the cooling unit 6 and the expansion cylinder 1. The mesh 15 of the present embodiment is formed by stacking one or a plurality of layers. It is composed of a reticulated body. This net 15
Is formed in a disk shape along the inner peripheral wall of the expansion cylinder 1 from a material having high thermal conductivity, for example, a metal such as copper. Further, the mesh 15 is joined to the inner surface of the cooling section 6 by joining means such as brazing, and the mesh 15 is also in contact with the inner surface (inner peripheral wall surface) of the expansion cylinder 1. It is arranged.

According to the first embodiment, since the mesh 15 is provided on the inner surface of the cooling section 6 so as to protrude toward the expansion space 11 as described above, the space between the cooling medium and the cooling section 6 and the expansion cylinder 1 is provided. The heat transfer surface area, compared to the case without the network 15,
It can increase dramatically. In addition, the refrigerant ejected from the communication passage 10 collides with the inner surface near the end of the expansion cylinder 1, and also collides with the mesh 15. Thereby, the refrigerant is well stirred in the expansion space 11, so that the heat transfer coefficient between the refrigerant and the cooling unit 6 and the expansion cylinder 1 is also improved.

As described above, according to the first embodiment, since the heat transfer surface area and the heat transfer coefficient in the expansion space 11 can be increased, the refrigeration efficiency can be effectively improved. As a specific design example of the first embodiment, a wire diameter: 51
The heat transfer surface area can be reduced by forming a structure in which ten nets 15 each having a line width of 76 μm are stacked.
Can be increased about 10 times as compared with the case without. (Second Embodiment) FIG. 2 shows a second embodiment of the present invention.
The difference from the embodiment is that a ring-shaped projection 3A is provided on the outer peripheral portion of the upper end surface of the displacer 3 and the outer diameter of the mesh body 15 is reduced so that the outer circumferential surface of the mesh body 15 and the inner circumference of the expansion cylinder 1 are reduced. The difference is that a gap 16 is provided between the wall and the wall so that the ring-shaped protrusion 3A of the displacer 3 can be inserted. Further, the communication passage 10 for ejecting the refrigerant is connected to the displacer 3.
Is open straight upward at the upper end surface.
It should be noted that the height of the ring-shaped projection 3A and the thickness of the laminated net 1
The height of 5 is set to the same height.

According to the second embodiment, with such a configuration, the expansion space 11 when the displacer 3 is at the top dead center is provided.
Can be reduced to a necessary minimum. At the same time, since the periphery of the mesh 15 is surrounded by the displacer 3, the refrigerant that has collided with the mesh 15 is stirred without escaping to the lower side of the expansion cylinder 1, and the refrigeration efficiency is further improved. (Third Embodiment) FIG. 3 shows a third embodiment of the present invention.
The difference from the embodiment is that the mesh 15 is formed into a cylindrical shape, and the outer peripheral surface of the cylindrical mesh 15 is
And the upper end face of the mesh body 15 is brought into contact with the inner face of the cooling section 6.

Further, a columnar projection 3B is provided at the center of the upper end surface of the displacer 3 and the size of the columnar projection 3B is adjusted to the center gap 17 of the cylindrical mesh body 15.
It is set to a size that can be inserted into the inside. Note that the height of the columnar protrusion 3B and the height of the laminated net 15 are set to be the same. Further, the communication passage 10 for ejecting the refrigerant is:
A plurality of cylindrical protrusions 3B of the displacer 3 are provided radially outward.

According to the third embodiment, with such a configuration, the expansion space 11 when the displacer 3 is at the top dead center is provided.
While reducing the volume of the
By providing the communication passage 10 which is the refrigerant outlet at a position close to the center of the mesh body 15, the effect of stirring the coolant by the mesh body 15 can be further improved, and the refrigeration efficiency can be improved.

In the second and third embodiments, the gaps 16 and 17 provided on the reticulated body 15 are set at the outer peripheral portion or the central portion of the displacer 3, but are not limited to the outer peripheral portion or the central portion. Even if a gap is provided at a position where another part of the displacer 3 can be inserted, the same effect (effect of reducing the volume of the expansion space 11 at the time of the top dead center of the displacer 3) can be obtained. (Fourth to Sixth Embodiments) FIGS. 4 to 6 show the fourth to sixth embodiments of the present invention.
This embodiment is different from the first to third embodiments in that a pin-like fin 18 is used instead of the net 15 as a heat transfer enhancer. As the shape of the fin 18, for example, a cylindrical or conical pin having a diameter of about 0.5 mm is used. Further, as the material of the fin 18, a metal material having a high thermal conductivity such as copper is used. In the fourth embodiment shown in FIG. 4, the above-mentioned pin-shaped fin 18 is driven into a mounting hole provided on the inner surface of the cooling unit 6 and brazed.
Here, in FIG. 4, many pin-shaped fins 18 are provided at predetermined intervals over the entire inner surface of the cooling unit 6.

In the fifth embodiment shown in FIG. 5, a large number of the above-mentioned pin-shaped fins 18 are provided only at the center of the inner surface of the cooling unit 6, and a gap 16 is formed on the outer peripheral side of the group of fins 18. . In the sixth embodiment shown in FIG. 6, the pin-shaped fins 18 are provided not on the inner surface of the cooling unit 6 but on the inner peripheral wall surface of the expansion cylinder 1, and the center gap 17 is provided. Also,
A large number of the pin-shaped fins 18 may be provided only on the outer peripheral side of the inner surface of the cooling unit 6, and a center gap 17 shown in FIG. (Seventh to Ninth Embodiments) FIGS. 7 to 9 show the seventh to ninth embodiments of the present invention.
An example is shown, which is different from the first to third examples in that a foam material 19 is used instead of the net 15 as the heat transfer enhancer. The foam material 19 is made of a metal material having a high thermal conductivity such as nickel, and is formed by forming a myriad of fine pores into a complicated form by a known method. The porosity is preferably 90% or more.

In the seventh embodiment shown in FIG. 7, the foamed material 19 is formed into a disk shape, disposed over the entire inner surface of the cooling unit 6, and joined to the inner surface of the cooling unit 6 by brazing or the like. The outer peripheral surface of the foam material 19 is in contact with the inner peripheral wall surface of the expansion cylinder 1. In the eighth embodiment shown in FIG. 8, the outer diameter of the foam material 19 is reduced, and the gap 16 is formed on the outer peripheral side.

In the ninth embodiment shown in FIG.
Is formed into a cylindrical shape, and a gap 17 is formed at the center thereof. The outer peripheral surface of this cylindrical foam material 19 is expanded with the expansion cylinder 1.
And the upper end surface of the foam material 19 is brought into contact with the inner surface of the cooling section 6. (Tenth to eleventh embodiments) FIGS. 10 to 11 show tenth to eleventh embodiments of the present invention, which are different from the first to third embodiments in that a large number of fine particles are used instead of the net 15. 20 is used. As the shape of the fine particles 20,
For example, spherical or needle-like particles are used. Here, in the case of the spherical fine particles 20, silver fine particles having a diameter of 70 nm are preferable. In addition, as a material of the fine particles 20, a metal material having a high thermal conductivity such as copper can be used in addition to silver.

In the tenth embodiment shown in FIG. 10, a group of fine particles composed of a large number of fine particles 20 is press-bonded over the entire inner surface of the cooling section 6 in the form of a disk having many voids. And by sintering to the inner surface of
The outer peripheral surface of the fine particle group is in contact with the inner peripheral wall surface of the expansion cylinder 1. In the eleventh embodiment shown in FIG. 11, a group of fine particles composed of a large number of fine particles 20 is joined not to the inner surface of the cooling section 6 but to the inner peripheral wall surface of the expansion cylinder 1 by sintering or the like. The upper end surface of the fine particle group is in contact with the inner surface of the cooling unit 6. (Twelfth Embodiment) FIG. 12 shows a twelfth embodiment of the present invention, in which a cooling unit 6 made of a metal material having high thermal conductivity such as copper is used.
Are formed with a large number of minute holes 21 in the inner surface thereof. As a method for forming the minute holes 21, a method such as processing with a drill, processing with a press, and etching can be used.

In the twelfth embodiment, as described above, a large number of minute holes 21 are formed in the inner surface of the cooling unit 6, so that the heat transfer surface area of the inner surface of the cooling unit 6 can be significantly increased, and the refrigeration efficiency is improved. it can. (Thirteenth Embodiment) FIG. 13 shows a thirteenth embodiment of the present invention, in which the fine holes 21 are formed on the inner peripheral wall surface of an expansion cylinder 1 made of a metal material having high thermal conductivity such as copper. .

The twelfth embodiment and the thirteenth embodiment may be combined to form the minute holes 21 on both the inner peripheral wall surface of the expansion cylinder 1 and the inner surface of the cooling section 6. In addition, as a specific design example of the minute hole 21 in the twelfth and thirteenth embodiments, the diameter: 0.4 mm, the depth: 3.
A 0 mm circular hole is drilled at an interval of 1.2 mm. According to the study of the present inventor, it is preferable that the minute hole 21 is a small hole having a diameter of 1.0 mm or less.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a first embodiment of an expansion device for a refrigerator according to the present invention.

FIG. 2 is a sectional view showing a main part of a second embodiment of the apparatus of the present invention.

FIG. 3 is a sectional view of a main part showing a third embodiment of the device of the present invention.

FIG. 4 is a sectional view showing a main part of a fourth embodiment of the device of the present invention.

FIG. 5 is a sectional view showing a main part of a fifth embodiment of the device of the present invention.

FIG. 6 is a sectional view showing a main part of a sixth embodiment of the apparatus of the present invention.

FIG. 7 is a sectional view of an essential part showing a seventh embodiment of the device of the present invention.

FIG. 8 is a sectional view showing a main part of an eighth embodiment of the device of the present invention.

FIG. 9 is a sectional view of a main part showing a ninth embodiment of the device of the present invention.

FIG. 10 is a sectional view showing a main part of a tenth embodiment of the device of the present invention.

FIG. 11 is a sectional view showing a main part of an eleventh embodiment of the device of the present invention.

FIG. 12 is a sectional view showing a main part of a twelfth embodiment of the device of the present invention.

FIG. 13 is a sectional view showing a main part of a thirteenth embodiment of the device of the present invention.

FIG. 14 is a configuration diagram showing the overall configuration of a conventional reverse Stirling cycle refrigerator.

FIG. 15 is a sectional view of a main part showing an example of a conventional expansion device for a refrigerator.

[Explanation of symbols]

1 ... Expansion cylinder, 3 ... Displacer, 6 ... Cooling unit,
DESCRIPTION OF SYMBOLS 10 ... Communication path for refrigerant ejection, 11 ... Expansion space, 15 ... Net, 16, 17 ... Gap, 18 ... Pin fin, 19 ... Foam material, 20 ... Microparticle, 21 ... Microhole.

Claims (7)

(57) [Claims] And 1. A cooling unit for cooling the cooled object, the cooling unit expansion cylinder were sealed end hermetically by, reciprocably is fitted in said expansion cylinder, the refrigerant injection
In the expansion device of the refrigerator and a displacer which forms an expansion space out, the inner surface of the cooling unit or the expansion cylinder are heat transfer enhancement body provided protruding in the expansion space, the heat transfer The promoter is one or more laminated nets
It is made of the expansion device of the refrigerator according to claim. 2. A cooling unit for cooling an object to be cooled, and an expansion cylinder whose end is hermetically sealed by said cooling unit.
And reciprocally fitted in the expansion cylinder,
And a displacer forming an expanded space to be provided.
In the expansion device of the refrigerator, the expansion unit is provided on an inner surface of the cooling unit or the expansion cylinder.
An expansion device for a refrigerator , wherein a heat transfer enhancer projecting into a space is provided, and the heat transfer enhancer comprises a plurality of pin-shaped fins . 3. A cooling unit for cooling an object to be cooled, and an expansion cylinder whose end is hermetically sealed by said cooling unit.
And reciprocally fitted in the expansion cylinder,
And a displacer forming an expanded space to be provided.
In the expansion device of the refrigerator, the expansion unit is provided on an inner surface of the cooling unit or the expansion cylinder.
An expansion device for a refrigerator , wherein a heat transfer enhancer projecting into a space is provided, and the heat transfer enhancer is made of a foam material . 4. A cooling unit for cooling an object to be cooled, and an expansion cylinder whose end is hermetically sealed by said cooling unit.
And reciprocally fitted in the expansion cylinder,
And a displacer forming an expanded space to be provided.
In the expansion device of the refrigerator, the expansion unit is provided on an inner surface of the cooling unit or the expansion cylinder.
The heat transfer promotion member projecting into the space is disposed, the expansion device of the refrigerator the heat transfer promotion body is characterized by comprising a number of fine particles. 5. A cooling section for cooling a cooled object, and an expansion cylinder whose end is hermetically sealed by said cooling section.
And reciprocally fitted in the expansion cylinder,
And a displacer forming an expanded space to be provided.
In the expansion device of the refrigerator, the expansion unit is provided on an inner surface of the cooling unit or the expansion cylinder.
A heat transfer enhancer projecting into the space is provided, and a ring-shaped protrusion is provided on an outer peripheral portion of the displacer.
And a gap is formed outside the entire heat transfer promoting body.
The ring-shaped protrusion can be inserted into the ring-shaped protrusion, and a coolant is provided inside the ring-shaped protrusion of the displacer.
An expansion device for a refrigerator, comprising a communication passage for ejection . 6. A cooling unit for cooling an object to be cooled, and an expansion cylinder whose end is hermetically sealed by said cooling unit.
And reciprocally fitted in the expansion cylinder,
And a displacer forming an expanded space to be provided.
In the expansion device of the refrigerator, the expansion unit is provided on an inner surface of the cooling unit or the expansion cylinder.
A heat transfer enhancer projecting into the space is provided, and a cylindrical protrusion is provided at the center of the displacer.
And the columnar protrusion is inserted into the center of the entire heat transfer enhancer.
Has become entrant, communication refrigerant ejected into the cylindrical projecting portion of the displacer
An expansion device for a refrigerator, comprising a passage . 7. A cooling unit for cooling an object to be cooled, and an expansion cylinder whose end is hermetically sealed by said cooling unit.
And reciprocally fitted in the expansion cylinder,
And a displacer forming an expanded space to be provided.
In the expansion device of the refrigerator , a large number of minute
An expansion device for a refrigerator, wherein a hole is provided .