JPS60211273A - Magnetic refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetic refrigerator comprising a working material for magnetic refrigeration and a magnetic field generator for applying or removing a magnetic field to the working material, and particularly relates to a magnetic refrigerator that has high efficiency and The present invention relates to a magnetic refrigerator suitable for achieving high reliability.

[Background of the invention]

The principle of a magnetic refrigerator is to utilize the magnetocaloric effect of magnetic materials such as gadolinium, mellium, and garnet (Gda Gas 012), which generate heat when a magnetic field is applied and absorb heat when the magnetic field is removed.

As a method of applying or removing a magnetic field to a stationary working material for magnetic refrigeration, for example, as shown in JP-A-58-127064 and JP-A-58-184471, the working material is placed at the center of a simple solenoid coil. Then, by periodically changing the amount of current flowing through the solenoid coil, or by passing a constant current through the solenoid coil to generate a constant magnetic field, the solenoid coil is periodically moved in its axial direction. It is known to do this by causing the working substance to enter and leave the coil.

These methods have the following problems.

First, when operating by periodically changing the amount of current flowing through the coil, changes in the magnetic field applied to the work material can be completely electrically controlled, and there are no moving parts, making it a highly reliable magnetic refrigerator. However, because the magnetization loss and eddy current loss of the coil winding material are large, the efficiency is significantly reduced.

On the other hand, when the coil is operated by periodically moving the coil, the stroke is large and the driving force is also very large due to the large electromagnetic force, so there is a problem that the driving mechanism becomes large.

[Purpose of the invention]

An object of the present invention is to provide magnetic refrigeration in which a working material for magnetic refrigeration is operated in a stationary state by motivating a magnetic field generator that generates a constant magnetism. A rotor is formed by disposing the coils on the outer peripheral surface of a cylinder or a cylindrical body. The magnetic field distribution generated by energizing the coil is such that the magnitude of the magnetic field periodically increases and decreases in the outer circumferential direction. When a plurality of magnetic refrigeration working materials are placed in a stationary state during this magnetic field change, the rotor rotates and
A changing magnetic field is applied to each workpiece according to the rotational change of the rotor and the magnetic field distribution generated by the coil.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

A plurality of superconducting coils 2 are arranged on the outer peripheral surface of a rotor 1 having a cylindrical or cylindrical body. A constant current is first applied to these superconducting coils via two removable power leads. Due to superconductivity, a constant magnetic field distribution is formed on the outer circumferential surface. This magnetic field distribution is such that the magnitude of the magnetic field increases and decreases periodically in the direction of the outer peripheral surface. In these magnetic field distributions, a plurality of magnetic materials such as gaddonium, gallium, garnet (Gd, Ga, 012), which are working materials 3 for magnetic field refrigeration, are arranged. There is a heat separator 4 made of a material with a small diameter. The low-temperature side heat transfer surface 3a and the high-temperature side heat transfer surface 3b of the magnetic material are filled with saturated helium gas 5 (approximately 12 mm/1 g) and liquid helium 6, respectively.
(approximately 1 atm, 4.2K). Below the helium gas, saturated superfluid helium 7 (about 12
mmtIg, 1.8K). These helium gas and superfluid helium are stored in a container 8, which includes a working material 3, a thermal separator 4. The helium gas 6 and the superfluid helium 7 are hermetically sealed and separated from the liquid helium 6 in terms of pressure by the container 8 . By the insulation vacuum layer 9, 1.8
The layers are insulated. 10 is a vacuum insulation container 10A is a ball bearing, and IOB is a hole into which liquid helium 6 is placed. The vacuum insulation container 10 containing the magnetic material 3 is always in a stationary state. The rotor 1 can be rotated by a shaft 11. When the rotor 1 rotates, according to the magnetic field distribution formed by the superconducting coil 2 and the rotational change of the rotor 1,
A magnetic field can be periodically applied to and removed from the work material 3. That is, when a magnetic field is applied to the working material, the temperature of the working material 3 rises, and heat is exhausted to the liquid helium 6 from the high temperature side heat transfer surface 3b. When the magnetic field is removed from the working material 3, the temperature of the working material 3 decreases and the helium gas 5 is condensed on the low temperature side heat transfer surface 3a of the working material 3. By periodically repeating heat exchange between the working material and the outside in this way, a refrigeration cycle between 1.8 and 4.2 can be constructed.

When the temperature of the working substance 3 is lower than the temperature of liquid helium 6, natural convection heat transfer of liquid helium 6, which is a high temperature refrigerant,
Convection must be prevented to prevent heat transfer between the working material 3 and the liquid helium 6. Also, the temperature of the working substance 3 is 1.8
The device is designed to prevent heat exchange between the helium gas 5 and the working material 3 due to natural convection heat transfer of the helium gas 5 when the temperature is higher.

Now, the magnetic field generated by the plurality of superconducting coils causes the plurality of work materials 3 arranged around the outer circumference of the rotor 1 to undergo a high magnetic field → a low magnetic field → a high magnetic field → in the direction around the circumference.
The magnetic field changes as low magnetic field... In order to effect this magnetic field change effectively, a cylinder 12 made of a material with high magnetic permeability such as iron is placed around the outer periphery of the work material 3, as shown in FIGS. 3 and 4, to converge the magnetic circuit. You may let them.

As a method of applying periodic magnetic field changes to the work material 3, the fifth method is as follows.
As shown in the figure, the working material may be placed inside the cylindrical rotor 1.

In the above explanation, the refrigeration cycles of 1.8, -4, and 2 will be explained. On the low temperature side, when helium is used as a refrigerant, the following temperature range can be set at the critical point 5.2. If the refrigerant is hydrogen, argon, nitrogen, etc., it is possible to set the temperature to a higher temperature. The high-temperature side only needs to be set at a higher temperature than the set temperature on the low-temperature side, and if an appropriate heat switch mechanism is provided on the high-temperature side, the refrigerant on the high-temperature side does not need to be limited to liquid. Figure 6 shows the low temperature side 4.2.
K.

An embodiment on the high temperature side 20 will be shown. As before, when the rotor 1 rotates according to the magnetic field distribution generated by the superconducting coil 2 incorporated in the rotor 1, the applied magnetic field increases or decreases to the plurality of work materials 3 arranged on the circumference. IOC is the bottom cover. This rotor 1 is immersed in liquid helium 14 in a container 13. Now, when a magnetic field is applied to the work material 3, helium gas 15 generated by a helium gas refrigerator (not shown) enters the flow path switching valve box 16, and passes through the pipe 17 to the high temperature side of the work material 3. While absorbing the heat generated in the work material 3 at the thermal wedge surface 18, the helium gas 21 enters the return flow path switching valve box 20 through the pipe 19, and returns to the external helium gas refrigerator. When the magnetic field is removed from the working material,
Since the temperature of the working material has decreased below 4.2, the helium gas 5 is transferred to the low temperature side heat transfer surface 3c of the working material 3.

Condenses and liquefies in 3d. Heat loads such as heat loss due to the rotation of the rotor 1 and the pump 25 that replenishes the object to be cooled 22 and the liquid helium 14 through the pipe 23 and the valve 24 are absorbed by recondensation of the evaporated helium gas. In the above explanation, it goes without saying that the rotor 1 does not necessarily need to be immersed in liquid helium, and that the superconducting coil may be cooled by forced cooling of helium gas, or it may be a normal conducting coil placed at room temperature. do not have.

〔Effect of the invention〕

According to the present invention, while the work material is stationary, a magnetic field is periodically applied to the work material by rotating a cylindrical body or a rotor in which a plurality of superconducting coils are arranged on the outer peripheral surface of the cylindrical body. Since the magnetic refrigerating machine can be removed or removed, it is possible to obtain a highly efficient and reliable magnetic refrigerator.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a magnetic refrigerator of the present invention, FIG. 2 is a cross-sectional view of a magnetic refrigerator of the present invention, and FIGS. 3 to 6 are cross-sectional views showing other embodiments of the present invention. It is. 1... Rotor, 2... Superconducting coil, 3... Working material for magnetic refrigeration, Death... Helium gas, 6... Liquid helium. Fig. 2 1ρ rotation/θno

Claims (1)

[Claims] A plurality of working substances for magnetic refrigeration that generate heat when a magnetic field is applied and absorb heat when the magnetic field is removed; a magnetic field generator that periodically applies and removes a magnetic field from the working substances; and a magnetic field generator that applies a magnetic field to the working substances. The magnetic refrigeration system operates while the work material is in a stationary state, and includes a heat exhaust mechanism with a heat switch that discharges heat to the high temperature side when the work material is removed, and a heat absorption mechanism with a heat switch that absorbs heat from the low temperature side when the magnetic field is removed from the work material. In a machine, a plurality of working substances are arranged on the outer or inner circumference of a rotor having a cylindrical body or a plurality of coils arranged around the circumference of the cylinder, and a current is applied to the coils to increase the strength of the magnetic field on the circumference of the rotor. 1. A magnetic refrigerator, characterized in that a magnetic field is periodically applied to or removed from the work material by forming a magnetic field distribution that increases and decreases, and by rotating the rotor.