JPH0737859B2 - Linear motor compressor for Stirling refrigerator - Google Patents

Description

TECHNICAL FIELD The present invention relates to a Stirling refrigerator having an expander that produces cold by the reciprocating motion of a displacer, and a linear motor compressor for compressing a refrigerant supplied to the expander. Regarding improvement.

(Prior Art) Conventionally, this free displacer type Stirling refrigerator is known as a type of small refrigerator that generates cold at an extremely low temperature level. For example, as shown in FIG. 3, this refrigerator has a combination of a compressor (a) that compresses a refrigerant gas and an expander (k) that expands the refrigerant gas discharged from the compressor (a). The compressor (a) is, for example, a hermetically sealed housing (b), a cylinder (c) fitted and fixed in the housing (b), and reciprocally movable in the cylinder (c). And a linear motor (f) as a drive source that reciprocally drives the piston (e). The piston (e) is fitted into the cylinder (c) and defines the compression chamber (d) in the inner space of the cylinder (c). . This linear motor (f) has an annular permanent magnet (g) arranged around the cylinder (c), and this magnet (g) applies a magnetic field to a cylindrical gap concentric with the center of the cylinder (c). generate. A circumferential portion of a substantially cup-shaped movable body (h) integrally fixed to the piston (e) at the central portion is disposed in the gap so as to be reciprocally movable, and the movable body (h) has an outer periphery on the outer periphery thereof. The drive coil (i) is wound around. Further, a coil spring for elastically supporting the piston (e) so as to reciprocate is formed between an outer bottom surface of the movable body (h) (opposite side of the piston (e)) and an inner bottom surface of the housing (b). A piston spring (j) is installed, and by energizing the drive coil (i) with an alternating current of a predetermined frequency, the coil (i) and the movable body (h) are driven by the action of the magnetic field passing through the gap. By reciprocating the piston (e) in the cylinder (c), a gas pressure of a predetermined cycle is generated in the compression chamber (d).

On the other hand, the expander (k) has a cylindrical cylinder (1), and the inside space of the cylinder (l) is divided into an expansion chamber (m) and a working chamber (n) in the cylinder (l). A free displacer (o) is reciprocally fitted. This displacer (o) is filled with a metal regenerator material (o ₁ ) (regenerative heat exchanger), and the regenerator material (o ₁ ) is used as an expansion chamber (m) and a working chamber (n). Communication holes (o ₂ ) and (o ₃ ) are opened to communicate with each other. Further, in the working chamber (n), a displacer spring (p) including a coil spring elastically supporting the displacer (o) so as to reciprocate is disposed. Further, the working chamber (n) is connected to the compressor (a) through the communication pipe (q).
Connected to the compression chamber (d) of the cylinder (1) by reciprocating the displacer (o) by the refrigerant gas pressure from the compressor (a) to expand the refrigerant gas in the expansion chamber (m). It is designed to generate cold in the cold head of the tip (for example, “Refrigerator for Cryogen
ic Sensors ", NASA Conference Publication 2287 etc.).

(Problems to be Solved by the Invention) In the above linear motor compressor (a), between the cylinder (c) and the piston (e), between the drive coil (i) outer peripheral surface and the yoke, and Micro gaps are required at three places between the inner peripheral surface of the coil (i) and the yoke,
In principle, the smaller the gap between these minute gaps, the higher the compressor efficiency. For example, if the gap between the cylinder (c) and the piston (e) is made small, gas leakage from the compression chamber (d) can be prevented and the compressor efficiency can be improved. Further, if the gap between the inner and outer peripheral surfaces of the drive coil (i) and the yoke is reduced, the drive efficiency of the piston (e) can be increased, which can contribute to the improvement of compressor efficiency.

However, the piston (e), cylinder (c),
It is necessary to arrange the coils (i), yokes, etc. in a concentric state. In reality, there is a limit in manufacturing and assembling to secure the concentricity and reduce the gaps in the above three places. It was difficult to improve machine efficiency.

An object of the present invention is to reduce the number of minute gaps so that the compressor efficiency can be increased with a simple structure.

(Means for Solving the Problem) In order to achieve the above-mentioned object, a solution means of the invention according to claim (1) is to form a compression chamber in a plunger and integrally dispose a coil on an outer peripheral wall of the plunger. To do.

Specifically, in the present invention, as shown in FIG. 1, a wall portion (3) of the housing (2) of the compressor is made of a yoke, and the housing (2) is provided at the center of the inner surface of the wall portion (3). A columnar part (4) protruding inward and an annular recess (5) are formed around the columnar part (4), and the end part of the columnar part (4) is exposed to the outside through the wall part (3). A communication hole (4a) for communication is provided. A cylindrical plunger (6) with a bottom, which defines a compression chamber (11) between the cylindrical portion (4) and the cylindrical portion (4) in the wall portion (3) of the housing (2), can slide. Mating outside. Further, at least on the inner peripheral surface of the recess (5),
An annular magnet (18) for generating a magnetic field is attached to the outer periphery of the columnar portion (4) with a predetermined distance from the outer peripheral surface of the columnar portion (4). Further, a coil (19) for reciprocating the plunger (6) by energizing alternating current is wound around at least the outer peripheral surface of the plunger (6) so as to face the magnet (18).

In the invention according to claim (2), in order to further improve the compressor efficiency, the plunger (6) has an open end portion on the bottom surface of the recess (5) of the housing (2) and a bottom portion on the housing (2). The walls are elastically supported by springs (15) and (16) so that they can reciprocate.

Further, in the invention according to claim (3), the coil (19) is prevented from being damaged by the reciprocating movement of the plunger (6), so that the coil (19) is prevented from being damaged by the spring (15). , (16) so that it is energized.

(Operation) With the above configuration, in the invention according to claim (1), since the coil (19) is wound around the outer periphery of the plunger (6) and integrally attached, the coil (19) has a predetermined size. When an alternating current having a frequency is applied, the coil (19) and the plunger (6) reciprocate due to the action of the magnetic field of the magnet (18), and the reciprocating motion of the plunger (6) causes the compression chamber (11).
The volume of is increased / decreased and the internal refrigerant is compressed in a predetermined cycle. In this structure, since the coil (19) and the plunger (6) are integrated, the minute gap portion is formed between the outer circumference of the cylindrical portion (4) of the wall portion (3) and the outer circumference of the plunger (6), and the coil. There are two places between the (19) and the magnet (18), the number of which is smaller than before, and this reduction ensures the concentricity of the cylinder (4), the plunger (6), the coil (19), etc. While facilitating the assembling, it is possible to reduce the gap of each of the minute gap portions, so that the compressor efficiency can be improved with a simple configuration.

In the invention according to claim (2), the plunger (6)
Is elastically supported by the springs (15) and (16) with respect to the housing (2), the spring (1) does the work when the plunger (6) returns to its original position after performing the compression work.
The elastic energy of 5) and (16) can be stored and used for the next compression work, whereby the driving efficiency of the plunger (6) can be increased and the compressor efficiency can be further improved.

Further, in the invention according to claim (3), the spring (1
Since 5) and (16) also serve as conductors for energizing the coil (19), the conductors are connected to the coil (1) inside the housing (2).
The conductor wire is not damaged due to the reciprocating motion of the plunger (6) as in the case of being wound on the wire 9), and the durability of the conductor wire can be improved.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIG. 2 shows the entire structure of a free displacer type Stirling refrigerator (A) according to an embodiment of the present invention. This refrigerator (A) is composed of a compressor (1) and an expander (21). . As shown in enlarged detail in FIG. 1, the compressor (1)
Has a closed cylindrical housing (2). The housing (2) is formed by closing the lower end opening of a non-conductive bottomed cylindrical body with a bottom wall (3) that constitutes a yoke. The housing (2) is provided at the center of the inner surface of the bottom wall (3). A cylindrical portion (4) extending in the up-down direction along the center line is provided in the inside of 2), and an annular recess (5) having the cylindrical portion (4) as an inner side surface is provided around the cylindrical portion (4). Are formed.

A bottomed cylindrical plunger (6) opened downward is slidably fitted to the cylindrical portion (4) of the bottom wall (3),
A portion surrounded by the plunger (6) and the columnar portion (4) is a compression chamber (11). A communication hole (4a) whose upper end opens into the compression chamber (11) is formed through the center of the columnar part (4), and one end of the communication pipe (12) is fitted into the lower end opening of this communication hole (4a). It is fixed.

The plunger (6) includes a thin-walled cylindrical portion (7) and ring-shaped upper and lower spring receiving portions (8) and (9) fitted to the upper and lower ends of the cylindrical portion (7) in an airtight manner. )
And a closing portion (10) that is fitted in an airtight manner at the upper end opening of the cylindrical portion (7), and spring fittings are provided on the outer peripheries of the upper and lower spring receiving portions (8) and (9), respectively. Grooves (8a) and (9a) are formed. Housing (2)
Spring support made of conductive material on the inner surface of the upper wall (13)
The upper end of the spring receiver (13) is integrally formed with an electrode (14) which penetrates the upper wall of the housing (2) and faces the outside. An upper spring (15) formed of a coil spring is provided between the upper spring receiving portion (8) of the plunger (6) and the spring receiving portion (13) of the upper wall of the housing (2), and the lower spring receiving portion (15). Similar lower springs (16) are respectively hung between 9) and the bottom of the recess (5), and the two springs (15) and (16) cause the plunger (6) to have an open end. Is elastically supported by the bottom surface of the concave portion (5) and the upper bottom portion thereof is reciprocally supported by the upper wall of the housing (2).

Further, a linear motor (17) for reciprocating the plunger (6) is provided. This linear motor (17) is an annular permanent member mounted on the outer inner peripheral surface of the recess (5) in the bottom wall (3) of the housing (2) at a predetermined distance from the outer peripheral surface of the cylindrical portion (4). A magnet (18) is provided, and a magnetic field of a predetermined strength is generated by the magnet (18) in the gap between the magnet (18) and the outer circumference of the columnar portion (4).

A coil (19) is wound around the outer circumference of the cylindrical portion (7) of the plunger (6) at a position facing the magnet (18). Although not shown, the coil (19) has one end electrically connected to the upper spring (15) and the other end electrically connected to the lower spring (16). A gas pressure of a predetermined cycle is generated in the compression chamber (11) by reciprocating the plunger (6) by supplying alternating current of a predetermined frequency to 19). Incidentally, (20) is a ground as the other electrode attached to the lower surface of the bottom wall (3) of the housing (2).

On the other hand, the expander (21) has a housing (22) in which a cylindrical hollow portion (23) is opened. This housing (2
The cylindrical cylinder (24) is concentrically fitted and fixed to the hollow portion (23) of the hollow portion (23) at the base end portion in a concentric manner with the hollow portion (23), and the tip end of the cylinder (24) is closed. It is said to be a cold head (25). A free displacer (26) is reciprocally fitted in the cylinder (24) so that the cavity (23) in the cylinder (24) and the housing (22) is attached to the front end of the cylinder (24) by the displacer (26). The expansion chamber (29) and the working chamber (30) on the housing (22) side (base end side of the cylinder (24)) are partitioned and formed. The displacer (26) is a cylindrical body (27) filled with a metal regenerator material (28) (regenerative heat exchanger), and the cylindrical body (27) has a space inside the expansion chamber (28). 29) and the working chamber (30) are provided with communication holes (27a) and (27b) for communicating with the working chamber (30) when the low-temperature refrigerant gas expanded in the expansion chamber (29) is directed to the working chamber (30). When the cold storage material (28) is cooled by the refrigerant gas to store cold heat in the cold storage material (28) and conversely the room temperature refrigerant gas goes from the working chamber (30) to the expansion chamber (29), the cold storage material (28) is used. It is designed to cool the gas. A displacer spring (31), which is a coil spring that elastically supports the displacer (26) in a reciprocating manner, is disposed in the working chamber (30). Further, the working chamber (30) is connected to the compression chamber (11) of the compressor (1) through the communication pipe (12), and the displacer (26) is driven by the refrigerant gas pressure from the compressor (1). ) Is reciprocated to expand the refrigerant gas in the expansion chamber (29) to generate cold in the cold head (25) at the tip of the cylinder (24).

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

With the start of operation of the refrigerator (A), an alternating current of a predetermined frequency is applied between the electrode (14) at the upper end of the housing (2) and the ground (20) of the bottom wall (3) in the compressor (1). hand,
An alternating current is applied to the coil (19) of the linear motor (17). With this energization, the coil (19) and the plunger (6) reciprocate by alternately expanding and contracting the upper and lower springs (15) and (16) by the action of the magnetic field generated by the magnet (18). , The volume of the expansion chamber (29) increases or decreases due to the reciprocating movement of the plunger (6), and the plunger (6)
When is moved downward, the refrigerant inside the compression chamber (11) is compressed in a predetermined cycle to generate a pressure wave of a predetermined cycle in the compression chamber (11). Since the compression chamber (11) communicates with the working chamber (30) of the expander (21) through the communication pipe (12), the plunger (6) descends and the pressure in the compression chamber (11) increases. Then, the pressurized refrigerant gas is supplied to the working chamber (30) to increase the pressure in the working chamber (30). This increase in pressure causes a difference between the working chamber (30) and the expansion chamber (29), and the pressure difference causes the displacer (26) to move toward the tip of the cylinder (24) while extending the displacer spring (31). To do. Since the working chamber (30) communicates with the expansion chamber (29) through the space in the displacer (26), the gas in the working chamber (30) passes through the displacer (26) and cools down in the next stage. It flows into the expansion chamber (29) while being cooled by the material (28), the pressure difference between the two chambers (29) and (30) disappears, and the displacer (26) is compressed by the contracting force of the spring (31) to the base end of the cylinder (24). Move to the side and return to the original position. Immediately after this, the plunger (6) of the compressor (1)
Rises and the pressure in the compression chamber (11) drops. For this reason,
Refrigerant gas in the working chamber (30) returns to the compression chamber (11) through the communication pipe (12), and the pressure in the working chamber (30) increases.
It is lower than 9). This working chamber (30) and expansion chamber (29)
The displacer (26) moves to the base end side of the cylinder (24) while contracting the displacer spring (31) due to the pressure difference between and, and the refrigerant gas in the expansion chamber (29) adiabatically expands to generate cold. . In the next stage, the expanded gas flows from the expansion chamber (29) through the displacer (26) to the working chamber (30) while applying cold heat to the regenerator material (28), and both chambers (29), (30 ), The displacer (26) moves to the tip side of the cylinder (24) by the extension force of the spring (31) and returns to the original position. 1
After the cycle ends, the same cycle is repeated thereafter, whereby the cold head (25) at the tip of the cylinder (24) is gradually cooled to the cryogenic temperature level.

In this case, the linear motor (1
The coil (19) of 7) is the cylindrical part (7) of the plunger (6).
Since it is wound around the outer circumference and integrally attached, the minute gap portion is formed between the outer circumference of the cylindrical portion (4) of the bottom wall (3) of the housing (2) and the inner circumference of the cylindrical portion (7) of the plunger (6). 2 between the outer circumference of the coil (19) and the permanent magnet (18)
As a result, the number of minute gaps becomes smaller than in the conventional case. Due to the reduction of the minute gap portions, the concentricity of the columnar portion (4), the plunger (6), the coil (19) and the like can be secured and the assembling thereof can be facilitated, while the gaps of the respective minute gap portions can be kept small. Therefore, the compressor efficiency can be improved with a simple configuration.

In addition, since the plunger (6) is elastically supported by the upper and lower springs (15) and (16) with respect to the housing (2), the plunger (6) moves downward and then performs compression work and then rises. The work of returning to the original state can be stored as elastic energy of both springs (15) and (16), and can be used for the next compression work, thereby increasing the driving efficiency of the plunger (6), The compressor efficiency can be further improved.

Further, since both the springs (15) and (16) also serve as conductors for energizing the coil, the conductors of the plunger (6) can be arranged as if the conductors were hung over the coil (19) in the housing (2). The conductor wire is not damaged by the reciprocating motion, and the durability of the conductor wire can be improved.

(Effect of the Invention) As described above, according to the invention of claim (1), the compression chamber in the linear motor compressor for the Stirling refrigerator is formed in the plunger, and the coil is wound around the outer periphery of the plunger. By integrally mounting, the number of the minute gaps can be reduced to two, the concentricity of each part can be secured, and the assembling can be facilitated, and the gaps of the minute gaps can be made small. Efficiency can be improved with a simple configuration.

According to the invention of claim (2), since the plunger is elastically supported by the spring in the compressor housing along the reciprocating direction, work other than the compression of the plunger is stored as elastic energy of the spring, and the next compression is performed. It can be used for work, the driving efficiency of the plunger can be increased, and the compressor efficiency can be further improved.

Further, according to the invention of claim (3), since the coil is energized by the spring, it is possible to improve the durability of the conductor and thus the compressor.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIG. 1 is an enlarged cross-sectional view of a compressor, and FIG. 2 is a cross-sectional view showing the overall structure of a Stirling refrigerator. FIG. 3 is a view corresponding to FIG. 2 showing a conventional example. (A) ... Refrigerator (1) ... Compressor (2) ... Housing (3) ... Bottom wall (wall part) (4) ... Cylindrical part (4a) ... Communication hole (5) ... Recessed part (6) ... Plunger ( 11)… Compression chamber (15), (16)… Spring (17)… Linear motor (18)… Magnet (19)… Coil (21)… Expander (26)… Displacer (29)… Expansion chamber

Claims (3)

[Claims] 1. A wall portion (3) constituting a yoke, and a columnar portion (4) and the columnar portion (4) at the center of the inner surface of the wall portion (3).
An annular recess (5) is formed around the
A housing (2) having a communication hole (4a) communicated with the outside from the end portion through a wall portion (3), and a cylindrical portion (4) of the housing (2) are slidably fitted to the outside. A bottomed cylindrical plunger (6) that defines a compression chamber (11) between the columnar portion (4) and at least the inner peripheral surface of the recess (5) and the outer peripheral surface of the columnar portion (4). And an annular magnet (18) which is attached with a space between them and generates a magnetic field between the outer circumference of the columnar part (4) and at least the outer peripheral surface of the plunger (6) wound so as to face the magnet (18). The coil (1
9) A linear motor compressor for a Stirling refrigerator, which is provided with and. 2. A plunger (6) is elastically supported by a spring (15) and (16) so that it can be reciprocated, with its open end on the bottom surface of the recess (5) and on the wall of the housing (2). The linear motor compressor for a Stirling refrigerator according to claim 1, wherein 3. The coil (19) is a spring (15), (16).
The linear motor compressor for a Stirling refrigerator according to claim 2, wherein the linear motor compressor is configured to be energized by.