JP2556939B2 - refrigerator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Stirling refrigerator for cooling an infrared detecting element to an extremely low temperature of about 80 Kelvin.

[0002]

2. Description of the Related Art FIG. 5 shows a structural example of a conventional Stirling refrigerator. In FIG. 5, the Stirling refrigerator is roughly composed of a compressor 1, a cold finger 2, a power source 35, and a first electric input amount controller 36. In the compressor 1, the piston 16 positioned by the support spring 18 is the first
The structure is such that it reciprocates inside the cylinder 17.
A lightweight sleeve 19 made of a non-magnetic material is connected to the piston 16, and a conductive material is wound around the sleeve 19 to form a movable coil 20. The moving coil 20
Is connected to a first lead wire 22 and a second lead wire 23 extending outward through the wall of the housing 21. These lead wires 22 and 23 have a first electric contact 24 and a second electric contact 25 on the outside of the housing 21, and are connected to the power source 35. An annular permanent magnet 26 and a yoke 27 are provided in the housing 21, and these form a closed magnetic circuit.

The movable coil 20 is the annular permanent magnet 2
6 and the yoke 27, the structure is such that it can reciprocate in the axial direction of the piston 16 within a gap 28 provided in a closed magnetic circuit. A permanent magnetic field exists in the gap 28 in the radial direction across the moving direction of the movable coil 20. The sleeve 19, the movable coil 20, the lead wires 22 and 23, the annular permanent magnet 26, and the yoke 27 described above constitute a linear motor 29 as a whole. The internal space above the piston 16 inside the first cylinder 17 is called a compression chamber 30. The compression chamber 30 is filled with a high-pressure working gas such as helium. Seals 18 and 19 are provided in the gap between the first cylinder 17 and the piston 16 so that the working gas in the compression chamber 30 does not pass through the gap between the first cylinder 17 and the piston 16. The above is the configuration of the compressor 1. On the other hand, the cold finger 2 has a cylindrical second
The displacer 5 is engaged with the cylinder 3 and the resonance spring 4 and reciprocates in the second cylinder 3 slidably. The space inside the second cylinder 3 is divided into two by the displacer 5, and the space above the displacer 5 is called a low temperature chamber 6 and the space below is called a high temperature chamber 7. A regenerator 8 and gas passage holes 9 and 10 are provided inside the displacer 5, and the low temperature chamber 6 and the high temperature chamber 7 communicate with each other through the regenerator 8 and the gas passage holes 9 and 10. The regenerator 8 is filled with a regenerator material 11 such as a copper wire mesh. The displacer 5 and the second cylinder 3 are arranged so that the working gas does not pass through the gap between the second cylinder 3 and the displacer 5.
Seals 12 and 13 are provided in the gap. Like the compressor 1, each chamber of the cold finger 1 is filled with a high-pressure working gas such as helium. The configuration of the cold finger 2 has been described above.

The compression chamber 30 of the compressor 1 and the high temperature chamber 7 of the cold finger 2 communicate with each other via a cooler 14. In addition, the compression chamber 30, the high temperature chamber 7,
The regenerator 8 and the low temperature chamber 6 communicate with each other, and these chambers as a whole are referred to as a working chamber 15. A temperature detector 37 is provided above the cold room 6 of the cold finger 2 to detect the temperature of the cold room 6. The first electric input amount controller 36 determines the electric input amount to be supplied to the linear motor 29 by using the detection signal of the temperature detector 37 as an input, and the power source 35 supplies the linear motor 29 with the electric signal based on the determination. Output.

The operation of the conventional refrigerator configured as described above will be described. Electric contacts 24, 25 from the power supply 35
When an alternating current is supplied to the movable coil 20 via the lead wires 22 and 23, a Lorentz force acts on the movable coil 20 in the axial direction due to the interaction with the permanent magnetic field in the gap 28. As a result, the assembly including the piston 16, the sleeve 19, and the movable coil 20 moves up and down in the axial direction of the piston 16. When a sinusoidal current is applied to the movable coil 20, the piston 16 reciprocates inside the cylinder 17,
A sinusoidal wave is applied to the gas pressure in the working chamber 15 from the compression chamber 30 to the low temperature chamber 6. Due to this sinusoidal pressure wave, the flow rate of the gas passing through the regenerator 8 in the displacer 5 changes periodically, and a pressure loss due to the regenerator 8 causes a periodic pressure difference between both ends of the displacer 5. Due to this pressure difference and resonance of the resonance spring 4, the displacer 5 including the regenerator 8 reciprocates in the axial direction in the cold finger 1 at the same frequency as the piston 16 but at a different phase.

When the piston 16 and the displacer 5 move while maintaining an appropriate phase difference, the working gas enclosed in the working chamber 15 constitutes a thermodynamic cycle known as the "reverse Stirling cycle", mainly in the low temperature chamber 6. Generate cold heat. Regarding the above-mentioned "reverse Stirling cycle" and its cold heat generation principle, see "Cryocoolers" in the literature.
(G. Walker, Plenum Press, Ne
w York, 1983, PP. 117-123).

The principle will be described below. The gas in the compression chamber 30 compressed by the piston 16 is the cooler 1.
The compression heat is cooled while flowing through 4 and flows into the high temperature chamber 17, the gas passage hole 9 and the regenerator 8. The working gas is pre-cooled in the regenerator 8 by the cold heat stored before the half cycle,
Enter the low greenhouse 6. Then, when most of the working gas enters the low temperature chamber 6, expansion starts and cold heat is generated in the low temperature chamber 6. The working gas then returns through the flow path and enters the compression chamber 30 while releasing cold heat to the regenerator 8 in the reverse order. At this time, heat is taken from the tip of the cold finger 2 to cool the outside.
In this way, when most of the working gas returns to the compression chamber 30, compression starts again and moves to the next cycle. By repeating the above process, the temperature of the low temperature chamber 6 gradually decreases, and reaches an extremely low temperature of, for example, about 80 Kelvin. In such a cooling process, the first electric input amount controller 36 controls the electric input amount so that the amplitude of the piston 16 is always maximized in the movable range so that the cooling rate does not decrease. In the steady cooling, the temperature of the cold room 6 of the cold finger 2 is detected by the temperature detector 37, and the detected signal is used as an input to the first electric input amount controller 36 to determine that the temperature fluctuation of the cold room 6 is 0. The amount of electric input supplied from the power supply 35 to the linear motor 29 is controlled so as to be 1 Kelvin or less.

[Means for Solving the Problems]

The conventional device as described above has the following problems. When the power supply is activated, an inrush current is generated and exceeds the electric input amount determined by the first electric input amount controller and is supplied to the movable coil. In addition, when the amount of electric input supplied to the movable coil rapidly increases, the vibration system constituted by the piston, the movable coil, and the support spring excessively responds, resulting in a very large amplitude. Due to the above-mentioned phenomenon, when the power source is started, the amplitude of the piston moves beyond the movable range, and there is a problem that the parts collide and are damaged.

The present invention has been made to solve the above problems, and it is an object of the present invention to obtain a refrigerator in which the piston does not exceed the movable range when the power source is started and the collision and damage of parts can be prevented. Has an aim.

[0010]

In the refrigerator according to the present invention, the first electric input amount controller, which determines the amount of electric input supplied from the power source to the moving coil of the linear motor, is moved to the moving coil when the power source is started. First, gradually increase the electric input amount so that the electric input amount supplied to the
The second electric input amount controller for instructing the electric input amount controller is provided.

[0011]

The second electric input amount controller according to the present invention is
By gradually increasing the amount of electrical input supplied to the moving coil when the power is turned on so that the amount of electrical input does not increase suddenly, it is possible to prevent the piston amplitude from moving beyond the movable range and colliding and damaging parts. To do.

[0012]

【Example】

Example 1. FIG. 1 is a diagram showing an embodiment of the present invention.
1 to 37 are the same as the above-mentioned conventional device, and the description thereof is omitted here. 38 is a first for preventing the amount of electric input supplied to the movable coil when the power source 35 is activated from increasing sharply.
2 is a second electric input amount controller for instructing the electric input amount controller 36 of FIG.

In such a device, the second electric input amount controller 38 commands the first electric input amount controller 36 to increase the current in the curved shape shown in FIG. Based on this command, the first electric input amount controller 36 determines the current, and based on this determination, the power supply 35 changes the current supplied to the linear motor 29. As a result, it is possible to prevent the components from colliding when the power is started. Although FIG. 2 shows an example in which the current supplied to the linear motor 29 is controlled, the present invention can be implemented by controlling the voltage in exactly the same manner.

Example 2. In the first embodiment, the current at the time of starting the power supply 35 was changed in a curved shape, but the same effect can be expected if the current is changed in a linear shape or a step shape as shown in FIG.

Example 3. In the first embodiment, the cold finger 1 and the compressor 2 are integrated into the Stirling refrigerator, but the cold finger 1 and the compressor 2 as shown in FIG. 4 are separated from each other via the connecting pipe 40. A similar effect can be expected in any shape of the Stirling refrigerator having the linear motor 29, such as the Stirling refrigerator of the type.

[0016]

As described above, according to the present invention, since the second electric input amount controller can be instructed to gradually increase the electric input amount when the power source is started, the second electric input amount controller can be instructed to gradually increase. There is an effect that the operation exceeding the movable range of the component due to the inrush current or the excessive response of the vibration system is suppressed, and thereby the damage due to the collision of the component can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a diagram showing how to control a current when the power source is activated in the first embodiment of the present invention.

FIG. 3 is a diagram showing how to control a current at power-on in a second embodiment of the present invention.

FIG. 4 is a sectional view showing Embodiment 3 of the present invention.

FIG. 5 is a sectional view showing a conventional Stirling refrigerator.

[Explanation of symbols]

 1 Compressor 2 Cold Finger 3 2nd Cylinder 5 Displacer 6 Low Greenhouse 7 High Greenhouse 16 Piston 17 1st Cylinder 29 Linear Motor 35 Power Supply 36 1st Electric Input Quantity Determiner 37 Temperature Detector 38 2nd Electric Input Quantity Determiner 40 Connecting pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Miyazawa 730 Kamimachiya, Kamakura City Mitsubishi Electric Engineering Co., Ltd. Kamakura Plant (56) References Japanese Patent Laid-Open No. 2-230060 (JP, A)

Claims (1)

(57) [Claims] 1. A compressor including a first cylinder, a piston that reciprocates in the first cylinder, a linear motor that reciprocates the piston by applying an alternating current, and a second cylinder. A displacer reciprocating in the second cylinder, a cold finger having a low temperature chamber and a high temperature chamber partitioned by the displacer, and a first electric input amount control for controlling an electric input amount applied to the linear motor. A power source for supplying an electric input amount to the linear motor according to the first electric input amount controller, and the first electric power so as to gradually increase the electric input amount to the linear motor when the power source is started. And a second electric input amount controller for instructing the input amount controller.