JPH0375455A - Linear-motor compressor for stirling refrigerator - Google Patents

Abstract

PURPOSE:To improve the efficiency of a compressor by a simple structural constitution forming clearances at a reduced number of spots, attaching a circular magnet to the inner circumferential surface of a hollow part with a specified clearance from the outer circumferential surface of a column and providing a coil to the outer circumferential surface of a plunger for reciprocating the plunger by application of an AC current. CONSTITUTION:A coil 19 is wound on the outer circumference of a plunger 6 as an integral part. When an AC current of a specific frequency is passed through the coil 19, the magnetic field of a magnet 18 acts to make the coil 19 and the plunger 6 move in reciprocating motion so that the reciprocation of the plunger 6 making the capacity of a compression chamber 11 change alternately causes refrigarant inside it to be compressed at a specific frequency. In this constitution clearances are formed at two spots, one clearance between the outer circumference of a column 4 of a wall part 3 and the inner circumference the plunger 6 and the other clearance between the coil 19 and the magnet 18. The reduction in number of clearances as compared with convertional model helps to secure connectricity of the column 4, plunger 6, coil 19, and the like and thus facilitates the assembly. Consequently, each of the clearances can be made narrower and an improvement of the efficiency of the compressor can be achieved by a simple structural constitution.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a Stirling refrigerator that has an expander that generates cold by reciprocating motion of a displacer. Regarding improvements.

(Prior Art) This free displacer type Stirling refrigerator has been known as a type of small refrigerator that generates cryogenic cold. For example, as shown in FIG. 3, this refrigerator combines a compressor (a) that compresses refrigerant gas and an expander (k) that expands the refrigerant gas discharged from the compressor (a). The above compressor (a
) includes, for example, a sealed housing (b), a cylinder (C) fitted and fixed in the housing (b), and a cylinder (c) fitted in the cylinder (C) so as to be able to reciprocate.
It includes a piston (e) defining a compression chamber (d) in an inner space, and a linear motor (f') serving as a drive source for reciprocating the piston (e). This linear motor (
r) has an annular permanent magnet (g) arranged around the cylinder (C), and this magnet (g) causes the cylinder (c) to
A magnetic field is generated in a cylindrical gap concentric with the center of the A circumferential portion of a substantially cup-shaped movable body (h) integrally fixed to the piston (e) at the center is arranged in the gap so as to be able to reciprocate, and the outer periphery of the movable body (h) Drive coil (1
) is wrapped around it.

Further, between the outer bottom surface of the movable body (h) (opposite side to the piston (e)) and the inner bottom surface of the housing (b), there is a coil spring for elastically supporting the piston (e) so as to be able to reciprocate. A piston spring (j) is installed, and by applying an alternating current of a predetermined frequency to the drive coil (1), the coil (1) is activated by the action of the magnetic field passing through the gap.
) and the movable body (h) to reciprocate the piston (e) within the cylinder (C), the compression chamber (d)
The gas pressure is generated at a predetermined period.

On the other hand, the expander (k) has a cylindrical cylinder (g), and inside this cylinder <n>, the space inside the cylinder (g) is divided into an expansion chamber (n+) and a working chamber (n). A free displacer (0) is fitted so as to be able to reciprocate. This displacer (0) has a metal cold storage material (o+
) (regenerative heat exchanger), and the cold storage material (0
Communication holes (o2) and (03) are opened to allow the air pump 1) to communicate with the expansion chamber (Ill) and the working chamber (n), respectively. In addition, in the working chamber (n), there is a displacer (
A displacer spring (p) made of a coil spring that elastically supports the reciprocally movable displacer spring (p) is provided. Further, the working chamber (n) is connected to the compression chamber (d) of the compressor (a) via the connecting pipe (q), and the refrigerant gas pressure from the compressor (a) causes the displacer (0 ) is reciprocated to expand the refrigerant gas in the expansion chamber (+1), thereby generating cold in the cold head at the tip of the cylinder <n> (for example, "R").
ef'rigerator f'or Cryogen
lc5ensors, NASAConfere
nce Publica 11 on 2287, etc.).

(Problem 8 to be solved by the invention) By the way, in the above linear motor compressor (a), there is a gap between the cylinder (e) and the piston (e), between the outer peripheral surface of the drive coil (1) and the yoke, and Micro gaps are required at three locations between the inner circumferential surface of the coil (i) and the yoke, but in principle, the smaller the gaps between these micro gaps, the higher the compressor efficiency can be.

For example, if the gap between the cylinder (C) and the piston (e) is made minute, gas leakage from the compression chamber (d) can be prevented and compressor efficiency can be increased.

Further, by reducing the gap between the inner and outer circumferential surfaces of the drive coil (1) and the yoke, the driving efficiency of the piston (e) can be increased, which can contribute to improving compressor efficiency.

However, the piston <e), cylinder (C),
It is necessary to arrange the coil (1), yoke, etc. all concentrically, and in reality, there is a limit to manufacturing and assembling how to reduce the gaps at the three points above while ensuring this concentricity, and compression It was difficult to increase machine efficiency.

An object of the present invention is to increase compressor efficiency with a simple configuration by reducing the number of minute gaps.

(Means for Solving the Problem) In order to achieve the above object, the solving means of the invention according to claim (1) is such that a compression chamber is formed in the plunger, and a coil is integrally arranged on the outer peripheral wall of the plunger. do.

Specifically, in this invention, as shown in FIG. A cylindrical part (4) protruding inward, and an annular recess (4) around the cylindrical part (4).
5), from the end of the columnar part (4) to the wall part (3>
A communication hole (4a) is provided which communicates with the outside through the hole. Cylindrical portion (4) in the wall portion (3) of the housing (2)
A bottomed cylindrical plunger (6) defining a compression chamber (11) between the cylinder part (4) and the cylinder part (4) is slidably fitted to the outside. Further, an annular magnet (1) is provided on at least the inner circumferential surface of the recess (5) and generates a magnetic field between it and the outer circumference of the cylindrical portion (4).
8) is attached to the outer peripheral surface of the cylindrical portion (4) with a predetermined distance therebetween. Furthermore, a coil (19) for reciprocating the plunger (6>) by applying alternating current is wound around at least the outer peripheral surface of the plunger (6), facing the magnet (18).

In the invention according to claim '2J, in order to further increase the compressor efficiency, the plunger <6> has its open end connected to the bottom of the recess (5) of the housing (2>), and its bottom to the bottom of the recess (5) of the housing (2>). Spring (15) on each wall.

(16) to elastically support it so that it can reciprocate.

In addition, in the invention according to claim (3), in order to prevent the conductive wire for energizing the coil (19> from being damaged due to the reciprocating movement of the plunger (6>), the coil (19>) is connected to the spring (15). , (1B).

(Function) With the above configuration, in the invention according to claim (1), the coil (19) is wound around the outer periphery of the plunger (6> and is integrally attached), so that the coil (19) has a predetermined When a frequency alternating current is applied, the coil (19> and plunger (6) reciprocate due to the action of the magnetic field from the magnet (18), and the volume of the compression chamber (11) increases or decreases due to the reciprocating movement of the plunger (6>). The refrigerant inside the refrigerant is compressed at a predetermined period.In this structure, the coil (19) and plunger (6) are integrated, so the minute gap is formed by the cylindrical part of the wall (3). (4) There are two locations: between the outer periphery and the outer periphery of the plunger (8) and between the coil (19) and the magnet (18>), and the number of locations is reduced compared to the conventional one. (6) The concentricity of the coil (19) etc. is ensured to facilitate assembly, while the gaps in each of the minute gaps described above can be made smaller, thus improving compressor efficiency with a simple configuration. .

In addition, in the invention according to claim ('2J), the plunger (6
) is the spring (15) against the housing (2),
(1B), the work when the plunger (6) returns after performing compression work is stored as elastic energy in the springs (15) and (18), and used for the next compression work. This can increase the driving efficiency of the plunger (6) and further improve the compressor efficiency.

Furthermore, in the invention according to claim (3), the spring (1
5), (1B) also serves as a conducting wire for energizing the coil (19), so when passing the conducting wire to the coil <19> in the housing (2), it is necessary to connect it to the plunger (6).
The conductive wire is not damaged due to the reciprocating movement of the conductive wire, and the durability of the conductive wire can be improved.

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

FIG. 2 shows the overall configuration of a free displacer type Stirling refrigerator (A) according to an embodiment of the present invention, and this refrigerator (A) is composed of a compressor (1) and an expander (2). There is. As shown in enlarged detail in FIG.
) has a closed cylindrical housing (2). This housing (2) has a lower end opening of a non-conductive bottomed cylinder,
It is sealed by a bottom wall (3) constituting the yoke, and in the center of the inner surface of the bottom wall (3), there is a cylindrical part (4) extending vertically along the center line of the housing (2). Four annular portions (5) are formed around the cylindrical portion (4) and have the cylindrical portion (4) as an inner side surface.

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

The plunger (6) has a thin cylindrical portion (7), ring-shaped upper and lower spring bearing portions (8) which are externally fitted to the upper and lower ends of the cylindrical portion (7) in an airtight manner, respectively. 9), and a closing part (10) that is airtightly fitted into the upper end opening of the cylindrical part (7), and the upper and lower spring receivers have parts (8) and (9) on their outer peripheries. Spring fittings i'+1 (8a) and (9a) are formed respectively.A spring receiver <13> made of a conductive material is attached to the inner surface of the upper wall of the housing (2). An electrode (i4) penetrating the earthen wall of the housing (2) and facing the outside is integrally formed at the upper end.The upper spring holder of the plunger <6> is connected to the part (8>) and the housing (2>). Earthen wall spring receiver (1
There is an upper spring (1) made of a coil spring between the
5), but similar lower springs (16) are hooked between the lower spring receiver (9) and the bottom of the recess (5), and these two springs (15), (
16), the plunger <6> has an open end with a recess (5
) The bottom surface and the upper bottom portion are elastically supported by the earthen wall of the housing <2> so as to be able to reciprocate.

Furthermore, a linear motor (17>) is provided for reciprocating the plunger (6). An annular permanent magnet 08) attached to the surface at a predetermined distance from the outer peripheral surface of the cylindrical part (4)
, and this magnet 08) connects the magnet (18〉) and the ■ pillar part (
4) A magnetic field of a predetermined strength is generated in the gap between the outer periphery and the outer periphery.

Further, a coil (19) is wound around the outer periphery of the cylindrical portion (7) of the plunger (6) at a position facing the magnet (18). Although this coil (i9) is not shown, one end of the coil (i9) is The upper spring (15) is electrically connected to the lower spring (I6) at the other end, and the coil (19) is connected to the coil (19) by both springs (15) and (1B).
Gas pressure of a predetermined period is generated in the compression chamber (11) by applying an alternating current of a predetermined frequency to the housing (2) and reciprocating the plunger (6>). The bottom wall (3) is the ground as the other electrode attached to the bottom surface.

On the other hand, the expander (2)> has a housing (22) in which a cylindrical cavity (23) is opened.The opening of the cavity (23) of this housing (22>
24) is fitted and fixed concentrically with the cavity (23) at its proximal end in an airtight manner, and the distal end of the cylinder (24) is closed to form a cold head (25). This cylinder (
A free displacer (26) is fitted in the interior of the cylinder (24) so as to be able to freely reciprocate, and the displacer (2B) causes the cylinder (24) and the cavity (23) in the housing (22) to become an expansion chamber on the distal end side of the cylinder (24). (29) and the working chamber on the housing (22) side (base end side of the cylinder (24)) <30
〉 This displacer (26
) is a cylindrical body (27) filled with a metal cold storage material (28) (regenerative heat exchanger).
The internal space is divided into an expansion chamber (29) and an operation chamber (30).
) communicating holes (27a) and (27
b) is opened, and when the low-temperature refrigerant gas expanded in the expansion chamber (29> heads toward the working chamber (30>), the refrigerant gas cools the cold storage material (28) and transfers cold heat to the cold storage material (28). conversely, when the refrigerant gas at room temperature goes from the working chamber (30) to the expansion chamber (29), the gas is cooled by the cold storage material (28). is provided with a displacer spring (31) made of a coil spring that elastically supports the displacer (26) in a reciprocating manner.Furthermore, the working chamber (30> is connected to the connecting pipe (12>) through the connecting pipe (12>). The refrigerant gas pressure from the compressor (1) causes the displacer (26) to be connected to the compression chamber (11) of the compressor (1).
By reciprocating the refrigerant gas in the expansion chamber (29), cold is generated in the cold head (25) at the tip of the cylinder (24).

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

When the refrigerator (A) starts operating, an AC power source of a predetermined frequency is applied between the electrode (14) at the upper end of the housing (2) of the compressor (1) and the ground (20) of the bottom wall (3). Then, the coil (19) of the linear motor (17) is energized with alternating current. With this energization, the coil (19) and the plunger (
6) are both upper and lower springs (15), (16)
) is reciprocated while alternately expanding and contracting, and this plunger (
6), the volume of the expansion chamber (29) increases or decreases, and when the plunger (6) moves downward, the compression chamber <11)
The internal refrigerant is compressed at a predetermined period, and pressure waves at a predetermined period are generated within the compression chamber (11). This compression chamber (U) communicates with the working chamber (30> of the expander (2)) via the connecting pipe (12>), so the plunger (6) descends and the pressure in the compression chamber (11) decreases. When the pressure rises, pressurized refrigerant gas is supplied to the working chamber (30>) and the pressure in the working chamber (30) increases.This increase in pressure causes the working chamber (30>
> and the expansion chamber (29), and this pressure difference causes the displacer (26) to move toward the tip of the cylinder (24) while expanding the displacer spring (31). This working chamber (30) is a displacer (26
), so in the next step the gas in the working chamber (30) passes through the displacer (2B) and is cooled by the regenerator material (28) until it enters the expansion chamber. Flows into (29), both chambers (29).

(30) disappears, and the displacer (26) moves toward the cylinder (24) due to the contraction force of the spring (31).
Move to the W end and return to the original position. Immediately thereafter, the plunger (6) of the compressor (1>) rises and the compression chamber (11)
) pressure decreases. Therefore, the refrigerant gas in the working chamber (30) returns to the compression chamber l[) via the connecting pipe (12), and the pressure in the working chamber (30) becomes lower than that in the expansion chamber (29).

This pressure difference between the working chamber (30) and the expansion chamber (29) causes the displacer (2B) to move toward the proximal end of the cylinder (24) while contracting the displacer spring (31). ) The refrigerant gas within ) expands adiabatically and generates cold. In the next step, the expanded gas flows from the expansion chamber (29) through the displacer (2B) to the working chamber (30) while imparting cold heat to the cold storage material (28), and both chambers (29), (30) ) disappears, and the displacer (26) moves toward the tip of the cylinder (24) due to the stretching force of the spring (31>) and returns to its original position.This completes one cycle, and the same cycle is repeated thereafter. By repeating this process, the cold head (25) at the tip of the cylinder (24) is gradually cooled down to an extremely low temperature level.

In this case, the linear motor (1) in the compressor (1)
The coil (19) of 7) is attached to the cylindrical part (7) of the plunger <6>.
) Since it is wrapped around the outer circumference and attached integrally,
The minute gap is formed by the cylindrical part (3) of the bottom wall (3) of the housing (2).
4) There are 2TL spaces between the outer circumference and the inner circumference of the cylindrical part (7) of the plunger (6), and between the outer circumference of the coil (19) and the permanent magnet (18), reducing the number of minute gaps compared to the conventional one. That will happen. This reduction in the micro-gap portion ensures concentricity of the columnar portion (4), plunger (6〉, coil (19), etc.) and facilitates assembly, while keeping the gap between each micro-gap portion small. Compressor efficiency can be improved with a simple configuration.

Further, since the plunger (6) is elastically supported by the upper and lower springs (15) and (113) with respect to the housing (2), the plunger (8) moves upward after performing compression work by moving downward. The work of returning to the original position can be stored as elastic energy in both springs (15) and (1B), and it can be used for the next compression work, thereby increasing the driving efficiency of the plunger (6). Compressor efficiency can be further improved.

Furthermore, since the above springs (15) and (1B) also serve as conductors for energizing the coil, the conductors can be connected to the housing (
2) The conductor wire is not damaged due to the reciprocating movement of the plunger (6) unlike in the case where it is passed over the coil (19) in the coil (19), and the durability of the conductor wire can be improved.

(Effect of the invention) As explained above, according to the invention according to claim (1), the compression chamber in the linear motor compressor for a Stirling refrigerator is formed inside the plunger, and the coil is wound around the outer circumference of the plunger to form an integral part. By attaching them to the same position, the number of minute gaps can be reduced to two, ensuring concentricity of each part and making assembly easier, and the gap between each minute gap can be made smaller. Efficiency can be improved with a simple configuration.

Further, according to the invention according to claim (2), the plunger is elastically supported by a spring in the compressor housing along the reciprocating direction, so that work other than compression of the plunger is stored as elastic energy of the spring, and the work for the next compression is stored as elastic energy of the spring. It can be used for work, increasing the driving efficiency of the plunger and further improving the compressor efficiency.

Furthermore, according to the invention according to claim (3), since the coil is energized by a spring, the durability of the conductor and the compressor can be improved.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is an enlarged sectional view of a compressor, and FIG. 2 is a sectional view showing the overall configuration of a Stirling refrigerator. FIG. 3 is a diagram corresponding to FIG. 2 showing a conventional example. (A)... Refrigerator (1)... Compressor (2)... Housing (3)... Bottom wall (wall) (4)... Cylindrical part (4a)... Communication Hole (5)...Recess (6)...Plunger (11)...Compression chamber (15), (18)...Spring (17>...
Linear motor (18>... Magnet (19)... Coil <2))... Expander (2B>... Displacer (29>... Expansion chamber (A) (1) (2) ( 3) (4) (5) (6) (11) (15) (17) (18) <19> (2)) (26) (29) Refrigerator compressor housing bottom wall (wall) Cylindrical recess Plunger compression chamber (16)... Spring... Linear motor... Magnet... Coil... Expander... Displacer... Expansion chamber

Claims (3)

[Claims] (1) It has a wall portion (3) that constitutes a yoke, and the wall portion (3)
A cylindrical part (4) is formed at the center of the inner surface of the cylinder, and an annular recess (5) is formed around the cylindrical part (4), which communicates with the outside through the wall part (3) from the end of the cylindrical part (4). Communication hole (4a)
a bottomed cylinder that is slidably fitted externally to the cylindrical part (4) of the housing (2) and defines a compression chamber (11) between the cylindrical part (4) and the cylindrical part (4); A shaped plunger (6) is attached to at least the inner peripheral surface of the recess (5) at a predetermined distance from the outer peripheral surface of the cylindrical portion (4), and generates a magnetic field between the outer periphery of the cylindrical portion (4) and the outer periphery of the cylindrical portion (4). a ring-shaped magnet (18), and a coil (19) that is wound around at least the outer peripheral surface of the plunger (6) facing the magnet (18), and that causes the plunger (6) to reciprocate when energized with alternating current.
A linear motor compressor for a Stirling refrigerator, characterized by comprising: (2) The plunger (6) is elastically supported at its open end on the bottom of the recess (5) and on the wall of the housing (2) by springs (15) and (16), respectively, so as to be able to reciprocate. The linear motor compressor for a Stirling refrigerator according to claim (1), characterized in that: (3) The coil (19) has springs (15) and (16)
3. The linear motor compressor for a Stirling refrigerator according to claim 2, wherein the linear motor compressor is configured to be energized by.