CN101256874B - Permanent magnetism magnetic body system for rotating magnetic refrigerating device - Google Patents

Abstract

A permanent magnet system for a rotating magnetic refrigerator. The permanent magnets in the stator are composed of two permanent magnet blocks whose spatial positions differ by 180 degrees. The two permanent magnet blocks are magnetized in the same direction and along the radial direction of the stator. The stator magnet yoke is hollow cylindrical and made of magnet metal material; two permanent magnet blocks are fixed on the inner wall of the magnet yoke; consistent, and the other arc surface is concentric with the inner cavity wall of the permeable magnet yoke. The center point of the rotor coincides with the geometric center point of the stator yoke. The rotor core is a cylinder with a central hole or a cylinder with both sides cut off, and is set on the rotor shaft. The magnetic working medium is closely attached to the two circular arc surfaces of the rotor core. The magnetic working fluid area is arc-shaped, has a certain radial thickness, and has a certain gap with the permanent magnet block of the stator. The invention can generate much higher magnetization field strength than two permanent magnets placed parallel to each other.

Description

A permanent magnet system for a rotating magnetic refrigerator

technical field

The invention relates to a permanent magnet system, in particular to a permanent magnet system for a room temperature rotary magnetic refrigerator.

Background technique

The mechanical gas compression cycle refrigeration technology that has been widely used for a long time has low refrigeration efficiency, which can only reach 5% to 10% of the Carnot cycle efficiency, and the working medium is generally chlorofluorocarbons (CFC) and other compounds. These working fluids will The destruction of the atmospheric ozone layer and the release of greenhouse effect gases have seriously affected the human ecological environment, so it is very important to develop environmentally friendly refrigeration technology.

As a new refrigeration method, magnetic refrigeration technology has the advantages of no pollution, no noise, and high reliability. It does not need to use substances that cause the destruction of the atmospheric ozone layer and gas compressors with complex structures, but only relies on the magnetocaloric effect of magnetic materials to achieve the purpose of refrigeration through repeated cycles of magnetization and demagnetization, and the efficiency is very high. Therefore, magnetic refrigeration technology is called a green and environmentally friendly refrigeration technology.

The so-called magnetic refrigeration is to use the magnetocaloric effect of magnetic materials (magnetic working fluid materials) for refrigeration. The working principle of magnetic refrigeration is based on the magnetocaloric effect of the magnetic working fluid material, that is, the magnetic working medium emits heat to the outside when it is magnetized, and absorbs heat from the outside when it is demagnetized. When the two processes are connected by a cycle, continuous refrigeration can be achieved. the goal of. Since the magnetization of magnetic refrigeration materials is achieved through magnets, magnets are a key component of magnetic refrigeration equipment. According to the physical characteristics of the magnetic working medium, the stronger the magnetization field, the more significant its magnetocaloric effect. In order for the magnetic working fluid to generate a sufficiently large temperature difference, the magnet is required to generate a sufficiently strong magnetic field.

Historically, the high-field-strength magnet systems used in magnetic refrigeration prototypes were all superconducting magnets, but before the superconducting technology failed to achieve large-scale civilian use, it was obviously unrealistic to use superconducting magnets in household magnetic refrigerators. Its high cost makes it difficult for room temperature magnetic refrigeration technology to be widely used. In order to reduce the production and operating costs of magnetic refrigerators, high-performance permanent magnets are currently used to replace the earlier superconducting magnets.

In a rotary room temperature magnetic refrigerator, Bohigas used two NdFeB (NdFeB) permanent magnets to be placed parallel to each other to generate a field strength of 0.3T between the magnet gaps, and only obtained a cooling temperature span of 1.6K, which is very large. To a certain extent, the magnetocaloric effect function of the magnetic refrigeration material cannot be brought into play, so the simple permanent magnet magnetic circuit design cannot meet the field strength required by the room temperature magnetic refrigerator. In order to obtain a higher-strength magnetization field and increase the cooling temperature span and cooling power of the magnetic refrigerator, people have produced high-field-strength NdFeB permanent magnets on the basis of a hollow cylindrical magnetic field source based on Halbach's rotation theorem. Although a magnet with this structure can generate a high-intensity magnetization field, it requires more permanent magnet materials and is more difficult to process.

Contents of the invention

The purpose of the invention is to propose a high field strength permanent magnet system for rotating magnetic refrigerators, the invention can produce much higher magnetization field strength than two permanent magnets placed parallel to each other, and can overcome the existing Halbach-based The permanent magnet system based on the hollow cylindrical magnetic field source based on the rotation theorem has disadvantages such as many consumables and difficult processing.

The permanent magnet system of the present invention is composed of a stator and a rotor.

The stator is composed of two parts: a permanent magnet and a permeable yoke. The permanent magnet part is composed of two permanent magnet blocks whose spatial positions differ by 180 degrees. The two permanent magnet blocks have the same magnetization direction and are along the radial direction of the stator. The magnetic yoke is composed of a hollow cylindrical metal material with good magnetic permeability. Its radial thickness is determined according to the needs of magnetic conduction. In principle, the magnetic flux density in the magnetic yoke is within a reasonable range. Not too high, not too low. Because if the magnetic flux density in the magnetic yoke is too high, the reluctance in the magnetic circuit will be greatly increased, and if the magnetic flux density is too low, the material of the magnetic yoke will be wasted. The two permanent magnet blocks are fixed on the inner cavity wall of the permeable magnet yoke.

The rotor mainly includes three parts: the rotating shaft, the magnetic core and the magnetic working medium. The shaft is cylindrical and made of metal material. The magnetic core is made of high-performance metal magnetic material. The shape is a cylinder with a central hole or a cylinder with both sides cut off. It is set on the shaft, and the shaft is located at the center of the rotor. . The magnetic working fluid is divided into two pieces, which are respectively installed on the two outer arc surfaces of the magnetic core, symmetrical to the rotating shaft, and their spatial positions differ by 180 degrees.

The main function of each component in the permanent magnet system is: the permanent magnet in the stator part generates a two-pole permanent magnetization field in its inner space, and the permeable yoke in the stator and the permeable core in the rotor provide the permanent magnetization The field provides a good magnetic path, and the shaft is used to support and drive the rotor. When the rotary magnetic refrigerator is working, the rotor of the permanent magnet system rotates under the drive of external force. When the area occupied by the magnetic working fluid rotates under the permanent magnet block of the stator, most of the magnetic flux generated by the permanent magnet flows through the magnetic working medium. At this time, the magnetic working medium receives the largest magnetization field and its temperature is the highest. With the rotation of the rotor, the magnetization field in the magnetic working medium area becomes smaller and smaller, and the magnetic working medium begins to demagnetize. When the rotor rotates through a 90-degree space angle, most of the magnetic flux generated by the permanent magnet flows through the magnetic core instead of the magnetic working medium, and the magnetic field suffered by the magnetic working medium is the smallest. At this time, its The temperature becomes the lowest. With the further rotation of the rotor, the magnetization field suffered by the magnetic working fluid becomes stronger and stronger, and its temperature also increases continuously. The magnetic working medium is periodically magnetized and demagnetized during the rotation of the rotor to generate the necessary magnetothermal power for magnetic refrigeration.

In order to make the magnetization field of the magnetic working medium area as close to zero as possible when the difference between the magnetic working medium area and the permanent magnet block is 90 degrees, install two Magnetic block, the gap between the two magnetic blocks and the stator permanent magnetic block is very small, so that when the rotor is in this position, the magnetic flux generated by the stator permanent magnetic block can directly pass through the rotor magnetic core without spreading to the magnetic field. quality area.

Compared with the existing system, the permanent magnet system of the present invention has the advantages of less permanent magnet material usage, simple processing, high magnetization field strength, small volume, light weight, simple and compact structure, high operating reliability, vibration and Low noise and other advantages.

In addition to being used for rotating magnetic refrigerators, the invention can also be used as other rotating high-field-intensity permanent magnet mechanisms.

Description of drawings

Fig. 1 structure diagram of permanent magnet system;

Fig. 2 working schematic diagram of permanent magnet system;

Fig. 3 structure diagram of permanent magnet system;

Fig. 4 working schematic diagram of permanent magnet system;

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

The permanent magnet system of the present invention is composed of a stator and a rotor. The stator is composed of two parts: a permanent magnet and a magnetically permeable yoke, and the rotor mainly includes three parts: a rotating shaft, a magnetically permeable core and a magnetic working medium.

Figure 1 shows one of the specific embodiments of the present invention. The permanent magnet in the stator is composed of two permanent magnet blocks whose spatial positions differ by 180 degrees. The two sides of the permanent magnet block on the cross section of the permanent magnet system shown in Figure 1 are straight lines, while the other two sides are circular arcs. , the axial end face of the permanent magnet block is a plane. The magnetization direction of the two permanent magnet blocks is the same, and the magnetization direction is consistent with the radial direction of the stator, as shown by the arrow in FIG. 2 . The magnetically permeable yoke is hollow cylindrical and made of magnetically permeable metal material. The two permanent magnet blocks are fixed on the inner cavity wall of the permeable magnet yoke. The shape of one arc surface of the permanent magnet block is consistent with the inner cavity wall of the magnet yoke, and the other arc surface is concentric with the inner cavity wall of the magnet yoke.

The shaft of the rotor is located at the center of the rotor, and the center point of the rotor shaft coincides with the geometric center point of the permeable magnet yoke. The rotor core is a cylinder with both sides cut off, with a central hole, and is set on the rotor shaft. The cross section of the rotor core is a long area with two arc sides, and the two longer sides It is a straight line, and the two shorter sides are circular arcs, and the magnetic working medium is close to the two circular arc surfaces of the rotor core. The magnetic working fluid area is arc-shaped, has a certain radial thickness, and has a certain gap between it and the permanent magnet block of the stator. The size of the gap can be determined according to the mechanical coordination requirements of the rotor rotation.

When the magnetic refrigerator is working, the rotor of the permanent magnet system rotates in a certain direction (clockwise or counterclockwise). When the area occupied by the magnetic working medium is located under the permanent magnet block of the stator, the magnetic working medium is subjected to a large magnetization field. The magnetic working fluid material is magnetized and its temperature rises. With the rotation of the rotor, the magnetization field in the magnetic working medium area becomes smaller and smaller, and the magnetic working medium begins to demagnetize. As shown in Figure 2, when the rotor rotates through a 90-degree space angle, the magnetic field suffered by the magnetic working medium is the smallest, and its temperature becomes the lowest at this time. With the further rotation of the rotor, the magnetization field suffered by the magnetic working fluid becomes stronger and stronger, and its temperature also increases continuously. When the rotor rotates through a 180-degree space angle, the magnetization and demagnetization process of the magnetic working medium completes a cycle, and its temperature change also completes a cycle, which can be used to achieve refrigeration.

This embodiment adopts NdFeB48 permanent magnet material, the radial height of the two permanent magnet blocks of the stator is 30 mm, the inner radius of the stator permeable yoke is 100 mm, and the radial gap between the stator permanent magnet block and the rotor permeable core is 10 mm , when the magnetic working fluid is located under the permanent magnet block of the stator, the magnetization field strength received by it reaches 1.2T, and when the magnetic working fluid is located between the two permanent magnet blocks of the stator, the magnetic field intensity received by it is less than 0.1T. If the relative geometric dimensions of the permanent magnet blocks are increased, the magnetizing field intensity received by the magnetic working fluid under the permanent magnet blocks of the stator will be further increased. For this structure, the radial magnetic pull generated by the permanent magnetization field on the rotor is zero.

Fig. 3 shows the second embodiment of the present invention. Its stator part is completely consistent with one of the embodiments. On the basis of one of the embodiments, install two magnetic blocks on the two straight sides of the rotor magnetic core, and the side of the two magnetic blocks close to the permanent magnet block of the stator is a circle concentric with the inner cavity wall of the magnetic yoke On the arc surface, the gap between the two magnetic blocks and the permanent magnet block of the stator should be as small as possible on the basis of ensuring the mechanical cooperation requirements of the rotor rotation, so as to ensure that the magnetic flux generated by the permanent magnet block of the stator is at When in the position, it can directly pass through the rotor magnetic block and the magnetic core without entering the magnetic working medium area.

When the magnetic refrigerator is working, the rotor of the permanent magnet system rotates in a certain direction (clockwise or counterclockwise). When the area occupied by the magnetic working medium is located under the permanent magnet block of the stator, the magnetic working medium is subjected to a large magnetization field. The magnetic working fluid material is magnetized and its temperature rises. With the rotation of the rotor, the magnetization field in the magnetic working medium area becomes smaller and smaller, and the magnetic working medium begins to demagnetize. As shown in Figure 4, when the rotor rotates through a 90-degree space angle, the magnetic flux generated by the permanent magnet block directly passes through the rotor core without diffusing into the magnetic working medium area. At this time, the magnetization field suffered by the magnetic working medium is basically zero, and its temperature becomes the lowest at this time. With the further rotation of the rotor, the magnetization field suffered by the magnetic working fluid becomes stronger and stronger, and its temperature also increases continuously. When the rotor rotates through a 180-degree space angle, the magnetization and demagnetization process of the magnetic working medium completes a cycle, and its temperature change also completes a cycle, which can be used to achieve refrigeration.

This embodiment uses NdFeB48 permanent magnet material, the radial height of the two permanent magnet blocks of the stator is 30 mm, the inner radius of the stator permeable yoke is 100 mm, and the radial gap between the stator permanent magnet block and the rotor permeable core is 10 mm , the radial gap between the stator permanent magnet block and the rotor magnetic block is 1 mm, and the magnetic field strength received by the magnetic working medium is 1.2T when it is located under the stator permanent magnetic block, and the magnetic working medium is located between the two permanent magnetic blocks of the stator The magnetizing field strength is basically zero. If the relative geometric dimensions of the permanent magnet blocks are increased, the magnetizing field intensity received by the magnetic working fluid under the permanent magnet blocks of the stator will be further increased. For this structure, the radial magnetic pull generated by the permanent magnetization field on the rotor is zero.

Claims (3)

1. A permanent magnet system for a rotary magnetic refrigerator, comprising a stator and a rotor, the rotor comprising a rotating shaft, a magnetically permeable core and a magnetic working fluid, it is characterized in that the stator is composed of a permanent magnet and a permeable yoke, and in the stator The permanent magnet is composed of two permanent magnets whose spatial positions differ by 180 degrees. The magnetization direction of the two permanent magnets is the same, and the magnetization direction is consistent with the radial direction of the stator; the two permanent magnets are fixed on the yoke On the wall of the inner cavity; the stator permeable yoke and the rotor permeable core together form the path of the magnetic flux generated by the permanent magnet block. 2. The permanent magnet system for a rotating magnetic refrigerator according to claim 1, wherein two sides of the permanent magnet block of the stator permanent magnet on the cross section of the permanent magnet system are straight lines, and the other two sides are straight lines. The axial end face of the permanent magnet block is a plane; the stator magnet yoke is hollow cylindrical and made of magnetic metal material; the shape of the arc surface of the permanent magnet block is consistent with the inner cavity wall of the magnet yoke, and the other An arc surface is concentric with the inner wall of the magnet yoke; the center point of the rotor coincides with the geometric center point of the stator magnet yoke; the rotor shaft is cylindrical and made of metal material; the rotor magnet core is a A cylinder or a cylinder with both sides cut off is set on the rotor shaft in the center of the rotor. The cross section of the rotor core is a circle or an elongated area with two arc sides. The elongated area has two longer dimensions The sides are straight lines, and the two shorter sides are circular arcs; the two magnetic working fluids are closely attached to the two outer arc surfaces of the rotor magnetic core, which are symmetrical to the axis, and their spatial positions differ by 180 degrees; the magnetic working fluids The area is arc-shaped, and there is a gap between it and the permanent magnet block of the stator. 3. The permanent magnet system for a rotating magnetic refrigerator according to claim 1, characterized in that, two straight lines are installed at positions 90 degrees apart from the magnetic working medium area on the two straight sides of the rotor magnet core. One magnetic block, the side of the two magnetic blocks close to the stator is an arc surface concentric with the inner cavity wall of the stator magnetic yoke; the gap between the two magnetic blocks and the stator permanent magnetic block should be small enough to ensure that the rotor On the basis of the mechanical coordination requirements of the rotation, ensure that when the magnetic block rotates close to the stator permanent magnetic block, the magnetic flux generated by the stator permanent magnetic block directly passes through the rotor magnetic block and the magnetic core without entering the magnetic working fluid area.

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