JPH055569A - Refrigerator - Google Patents

Abstract

PURPOSE:To obtain a refrigerator in which noise, a defect of a component due to an increase in an amplitude of a piston by a vibration, etc., from the exterior and a collision with other member, can be prevented. CONSTITUTION:As a support spring 32 for supporting a piston 5 in a compressor 1 of a refrigerator, a nonlinear spring like a conical spring in which a spring constant is varied due to a displacement, is used. Accordingly, when the piston 5 is vibrated in an excess amplitude, the spring constant of the spring is increased to brake the piston, and hence no collision with other member occurs.

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, for example, around 80K.

[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 divided into a compressor 1, a cold finger 2, and a connecting pipe 3 connecting them. The compressor 1 includes a cylinder 4 and a piston 5. The piston 5 is positioned by the support spring 7 and reciprocates inside the cylinder 4. A lightweight sleeve 8 made of a non-magnetic material is connected to the piston 5, and a conductor is wound around the sleeve 8 to form a coil 9. The coil 9 is connected to a first lead wire 11 and a second lead wire 12 which extend to the outside through the wall of the housing 10, and these lead wires 11 and 12 are provided outside the housing 10 with a first electrical contact 13 and It has a second electrical contact 14. Permanent magnet 1 in housing 10
5 and a yoke 16 are provided, and these constitute a magnetic circuit 17. The coil 9 is a gap 18 formed in a magnetic circuit 17 including a permanent magnet 15 and a yoke 16.
It has a structure capable of reciprocating in the axial direction of the piston 5 inside. A permanent magnetic field exists in the gap 18 in the radial direction across the moving direction of the moving coil. The space partitioned by the cylinder 4 and the piston 5 is called a compression chamber 17. The compression chamber 19 is filled with a high-pressure working gas such as helium. The working gas in the compression chamber 19 is the cylinder 4 and the piston 5.
The clearance between the cylinder 4 and the piston 5 is controlled to be a minute clearance of, for example, 50 μm or less to form the clearance seal 21 so as not to pass through the clearance. On the other hand, the cold finger 2 has a cylindrical low-temperature cylinder 22 and a displacer 24 slidably reciprocating in the low-temperature cylinder 22 and engaged by a resonance spring 23. The space inside the low temperature cylinder 22 is set by the displacer 24.
The space above the displacer 24 is called a low temperature chamber 25, and the space below it is called a high temperature chamber 26. A regenerator 27 and a gas passage hole 28 are provided inside the displacer 24, and the low temperature chamber 25 and the high temperature chamber 26 communicate with the regenerator 27 via the gas passage hole 28. A cold storage material 29 such as a wire net is filled. Similar to the compressor 1, high pressure working gas such as helium is filled in each chamber of the cold finger 2. The low temperature cylinder 22 and the displacer 24 are arranged so that the working gas does not pass through the gap between the low temperature cylinder 22 and the displacer 24.
A clearance seal 30 is provided in the gap.
The above is the configuration of the cold finger 2. The compression chamber 19 of the compressor 1 and the high temperature chamber 26 of the cold finger 2 are connected to the connecting pipe 3
Also, they are communicated with each other via a communication pipe 20. Further, the compression chamber 19, the space inside the connection pipe 3 and the communication pipe 20, the low temperature chamber 2
5, the high temperature chamber 26, the regenerator 27, and the gas passage hole 28 communicate with each other, and the entire space thereof is collectively referred to as a working chamber 31.

The operation of the conventional refrigerator configured as described above will be described. The assembly including the coil 9 and the piston 5 and the support spring 7 form a spring-mass resonance system.
When an alternating current having a frequency close to the resonance frequency of this resonance system is applied to the coil 9 via the electrical contacts 13 and 14 and the lead wires 11 and 12, the coil 9 interacts with the permanent magnetic field in the gap 18 to cause the axial movement. The Lorentz force acts in the direction, and the assembly including the piston 5 and the coil 9 reciprocates in the axial direction of the piston 5. As a result, the piston 5 reciprocates inside the cylinder 4 and gives a sinusoidal wave motion to the gas pressure in the working chamber 31. Due to the change in the flow rate of the gas passing through the displacer 24 and the regenerator 27 due to the sinusoidal pressure wave, the displacer 24 including the regenerator 27 reciprocates in the cold finger 2 in the axial direction at the same frequency as the piston 5 but at a different phase. .. The phase difference between the piston 5 and the displacer 24 is determined by the spring constant of the resonance spring 23 and the mass of the displacer 24. When the piston 5 and the displacer 24 move while maintaining an appropriate phase difference, the working gas enclosed in the working chamber 31 constitutes a thermodynamic cycle known as "reverse Stirling cycle",
Cold heat is mainly generated in the low temperature chamber 25. Regarding the above-mentioned "reverse Stirling cycle" and its cold heat generation principle, reference is made to "Cryocoolers" (G. Walker, p.
lenumPress, New York, 1983, p.
p. 95-177).

The principle will be briefly described below. The heat of compression of the gas in the compression chamber 19 compressed by the piston 5 is cooled while flowing through the connecting pipe 3, so that the high temperature chamber 2
6, it flows into the regenerator 27 and the gas passage hole 28. The working gas is pre-cooled in the regenerator 27 by the cold heat stored before the half cycle and enters the low temperature chamber 25. Then, when most of the working gas enters the low temperature chamber 25, expansion starts and cold heat is generated in the low temperature chamber 25. Working gas is then regenerator 2 in reverse order
While returning the cold heat to 7, it returns to the compression chamber 19 through the flow path.
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 19, compression starts again and moves to the next cycle. By the process as described above, the "reverse Stirling cycle" is completed and cold heat is generated.

[0005]

In the conventional device as described above, the amplitudes of the piston and the coil are changed by the vibration applied from the outside. Therefore, for example, when the refrigerator is installed in an environment such as an aircraft that receives a large amount of vibration from the outside, the amplitude of the piston increases and the piston and coil collide with other members such as the cylinder and the housing. There was a problem of noise and loss of parts. Also,
The amplitude of the displacer also changes due to the vibration given from the outside. Therefore, as in the case of the piston, there is a problem in that it collides with other members, resulting in noise and loss of parts.

The present invention has been made in order to solve the above problems, and an object thereof is to provide a refrigerator in which the piston does not collide with other members, and noise and loss of parts can be prevented. ..

Another object of the present invention is to provide a refrigerator which prevents the displacer from colliding with other members and prevents noise and loss of parts.

[0008]

In order to prevent the piston and the coil from colliding with other members, the refrigerator according to the present invention uses a non-linear spring having a characteristic that the spring constant increases as the displacement increases, as a supporting spring. It was what I had.

In order to prevent the displacer from colliding with other members, a refrigerator according to another invention of the present invention uses a non-linear spring having a characteristic that the spring constant increases as the displacement increases, as a resonance spring. ..

[0010]

In the present invention, the change of the spring constant of the support spring is small within the range of the piston amplitude required for normal cooling, but when the amplitude of the piston becomes excessive, the spring constant of the support spring increases and the piston is braked. With. The larger the piston amplitude, the greater this braking force.Therefore, even when the refrigerator is installed in an environment such as an aircraft that receives a large amount of vibration from the outside, the piston and coil do not collide with other members and noise is reduced. Also, the loss of parts can be prevented.

Further, in another invention of the present invention, the change of the spring constant of the resonance spring is small within the range of the displacer amplitude required for normal cooling, but if the amplitude of the displacer becomes excessive, the spring constant of the resonance spring increases. , Has the function of braking the displacer. As the amplitude of the displacer increases, this braking force increases, so even if the refrigerator is installed in an environment such as an aircraft that receives extremely large vibrations from outside, the pistons or coils will not collide and noise and loss of parts will occur. Can be prevented.

[0012]

【Example】

Example 1. FIG. 1 shows an embodiment of the present invention. In FIG. 1, 1 to 6 and 8 to 31 are exactly the same as the conventional device. The support spring 32 is a non-linear spring such as a cone spring. FIG. 3 is a diagram showing the relationship between the spring constant and the displacement of a cone spring. As shown in FIG. 3, the spring constant is constant in the region where the displacement is small, but beyond a certain displacement, the spring constant increases as the displacement increases.

In such a device, when the piston 5 vibrates with an excessive amplitude over a predetermined displacement, the spring constant of the support spring increases, and the piston 5 is braked. Since the larger the amplitude of the piston 5 is, the larger the braking force is, the piston or the piston or the coil may collide with other members even when the refrigerator is installed in an environment such as an aircraft that receives a very large vibration from the outside. It is possible to prevent noise and loss of parts. In this embodiment, a conical spring is used as an example of the non-linear spring, but other springs that can realize the characteristics of FIG. 3 or a spring whose spring constant and displacement are not constant as shown in FIG. The same effect can be obtained.

Example 2. FIG. 2 shows an embodiment of another invention of the present invention. In the figure, 1 to 22 and 24 to 31 are exactly the same as the conventional device. The resonance spring 33 is a non-linear spring having a characteristic that the spring constant increases as the displacement increases as shown in FIG. 3 or 4.

In such a device, when the displacer 24 vibrates beyond a predetermined displacement and has an excessive amplitude, the spring constant of the resonance spring increases and the displacer 24
Brake. Since the larger the amplitude of the displacer 24 is, the larger the braking force is, the displacer will not collide with other members even if the refrigerator is installed in an environment such as an aircraft that receives a great vibration from the outside, and noise and noise can be reduced. The loss of parts can be prevented. Figure 2
In the embodiment, the compressor in which the piston is driven by electromagnetic force is used, but the same effect can be obtained even in the compressor by other piston driving method.

[0016]

As described above, according to the present invention,
A simple method of using a non-linear spring having a characteristic that the spring constant increases as the displacement increases as the supporting spring increases the spring constant of the supporting spring to apply a braking force to the piston even if the amplitude of the piston increases. As a result, the piston can be prevented from colliding with other members, and noise at the time of collision and loss of parts can be prevented.

According to another aspect of the present invention, a simple method of using a non-linear spring having a characteristic that a spring constant increases as the displacement increases as a resonance spring is obtained.
Even if the amplitude of the displacer increases, the spring constant of the resonance spring increases and a braking force is applied to the displacer to prevent the displacer from colliding with other members, thus preventing noise at the time of collision and loss of parts. it can.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing Embodiment 2 of the present invention.

FIG. 3 is a diagram showing an example of a spring constant and displacement of a non-linear spring.

FIG. 4 is a diagram showing an example of a spring constant and displacement of a non-linear spring.

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

[Explanation of symbols]

 1 Compressor 2 Cold finger 3 Connection pipe 4 Cylinder 5 Piston 9 Coil 19 Compression chamber 22 Low temperature cylinder 24 Displacer 25 Low greenhouse 26 High greenhouse 27 Regenerator 32 Support spring 33 Resonant spring

Claims (1)

Claim: What is claimed is: 1. A cylinder, a coil which is provided in a magnetic flux created by a permanent magnet and can reciprocate by passing an alternating current, and a coil which is connected to the coil and reciprocates in the cylinder. A piston, a spring that supports the coil and the piston, a compression chamber partitioned by the cylinder and the piston, a tubular low temperature cylinder, and the inside of the low temperature cylinder is divided into a low temperature chamber and a high temperature chamber, and A displacer slidably reciprocating inside the low temperature cylinder;
In a refrigerator composed of a regenerator provided inside the displacer and a connecting pipe that communicates the high temperature chamber and the compression chamber, a non-linear spring whose spring constant increases as displacement increases is used as the spring. A refrigerator characterized in that. 2. A cylinder, a piston that reciprocates in the cylinder, a compression chamber partitioned by the cylinder and the piston, a cylindrical low temperature cylinder, and a low temperature chamber and a high temperature chamber inside the low temperature cylinder. And a displacer that slidably reciprocates inside the low temperature cylinder, a resonance spring that is provided inside the low temperature cylinder and that engages with one end of the displacer, and a regenerator provided inside the displacer, A refrigerator comprising a connecting pipe that connects the high temperature chamber and the compression chamber to each other, wherein a non-linear spring whose spring constant increases with an increase in displacement is used as the resonance spring.