A permanent magnet holding mechanism and its parameter design method

Abstract

This invention relates to a permanent magnet retaining mechanism and its parameter design method. Based on finite element simulation, a static magnetic field model of the permanent magnet retaining mechanism is constructed to obtain the relationship curves between the maximum retaining force and the radius of the moving iron core, and between the maximum retaining force and the thickness of the permanent magnet. The structural parameters of the permanent magnet retaining mechanism are determined according to the maximum retaining force requirement. These structural parameters include the height of the moving iron core, the radius of the moving iron core, the height of the permanent magnet, and the thickness of the permanent magnet. The permanent magnet retaining mechanism proposed in this invention determines its structural parameters based on finite element simulation, thereby improving the reliability of parameter design.

Description

Technical Field

[0001] This invention belongs to the field of power equipment technology, specifically relating to a permanent magnet holding mechanism and its parameter design method. Background Technology

[0002] For fast vacuum switches, when in the open position, a holding force is required to overcome the contact self-closing force, ensuring the moving contact remains stable in the open position while the gap between the moving and stationary contacts meets insulation requirements. When in the closed position, a holding force is required to overcome the electromagnetic repulsion between the contacts, ensuring tight contact between the moving and stationary contacts and thus achieving a low on-resistance, typically on the order of μΩ. Therefore, a holding unit capable of providing bidirectional holding force is indispensable in fast vacuum switches, and the holding force provided by the holding unit in both the open and closed positions must be designed based on the contact self-closing force and the maximum electromagnetic repulsion between the contacts.

[0003] Retention units can be divided into permanent magnet retention mechanisms, spiral spring retention mechanisms, and disc spring retention mechanisms. Among them, permanent magnet retention mechanisms have the advantages of simple structure, light moving parts, convenient installation, and low inertia, and are suitable for short-stroke low-voltage fast vacuum switches.

[0004] For permanent magnet holding mechanisms, the moving and stationary iron cores are often made of electrical pure iron, which has advantages such as superior electromagnetic performance, low coercivity, high permeability, and high dimensional accuracy. The permanent magnets are made of neodymium iron boron (N48SH) rare earth permanent magnet material, which has advantages such as strong coercivity, good stability, and high remanence. When the magnetic field strength of the permanent magnet is constant, its volume and mass are much smaller than those of traditional permanent magnet materials, providing conditions for equipment miniaturization. Due to the high cost of rare earth permanent magnets, the volume of the permanent magnet should be reduced while meeting the holding force requirements.

[0005] Therefore, it is necessary to invent a permanent magnet holding mechanism and its parameter design method. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a permanent magnet holding mechanism and its parameter design method.

[0007] The technical problem solved by this invention is achieved through the following technical solution:

[0008] A permanent magnet holding mechanism includes a connecting rod, a moving iron core, a permanent magnet, and a stationary iron core. The moving iron core is fitted onto the connecting rod, and the two ends of the moving iron core are respectively connected to the permanent magnet. The permanent magnet is externally connected to the stationary iron core. The stationary iron core is U-shaped and forms a gap with the moving iron core. The moving iron core moves up and down along the connecting rod between the two inner sides a and b of the stationary iron core under the drive of the connecting rod.

[0009] Moreover, the magnetic field generated by the permanent magnet forms a closed loop in the gap between the moving iron core and the stationary iron core and generates a holding force on the moving iron core. The holding force is the maximum holding force when the moving iron core moves to the inner sides a and b of the stationary iron core. The magnetic field distribution of the permanent magnet at a and b is symmetrical.

[0010] A method for designing parameters of a permanent magnet holding mechanism is proposed. Based on finite element simulation, a static magnetic field model of the permanent magnet holding mechanism is constructed to obtain the relationship curves between the maximum holding force and the radius of the moving iron core and the thickness of the permanent magnet. The structural parameters of the permanent magnet holding mechanism are determined according to the maximum holding force requirement. The structural parameters include the height of the moving iron core, the radius of the moving iron core, the height of the permanent magnet, and the thickness of the permanent magnet.

[0011] according to The principle determines the height of the moving iron core, where: R is the radius of the connecting rod, d is the thickness of the moving iron core, and σ is the height of the moving iron core. s F represents the yield strength of the moving iron core. em Maximum shear force;

[0012] The maximum holding force-moving iron core radius curve was obtained based on the static magnetic field model of the permanent magnet holding mechanism. The maximum holding force first increases and then decreases with the increase of the moving iron core radius. The moving iron core radius was determined to be the value corresponding to the highest point of the curve.

[0013] The height of the permanent magnet is the sum of the height of the moving iron core and the displacement of the moving iron core;

[0014] The maximum holding force-permanent magnet thickness curve was obtained based on the static magnetic field model of the permanent magnet holding mechanism. The maximum holding force increases rapidly at first and then gradually as the thickness of the permanent magnet increases. The thickness of the permanent magnet was determined according to the maximum holding force requirement.

[0015] The advantages and beneficial effects of this invention are as follows:

[0016] The permanent magnet holding mechanism proposed in this invention has the advantages of simple structure, light moving parts, convenient installation, and low inertia. Furthermore, its structural parameters are determined based on finite element simulation, which improves the reliability of parameter design. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the permanent magnet holding mechanism in this invention;

[0018] Figure 2 This is a flowchart illustrating the parameter design of the permanent magnet holding mechanism in this invention.

[0019] Figure 3 The maximum holding force-moving core radius curve provided for this invention;

[0020] Figure 4 The maximum holding force-permanent magnet thickness curve provided for this invention;

[0021] Figure 5 The holding force-displacement curve is a specific embodiment of the parameter design method for the permanent magnet holding mechanism provided by the present invention. Detailed Implementation

[0022] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0023] like Figure 1 As shown, a permanent magnet holding mechanism is innovative in that it includes a connecting rod 1, a moving iron core 2, a permanent magnet 3, and a stationary iron core 4. The moving iron core 2 is mounted on the connecting rod 1, and the two ends of the moving iron core 2 are respectively connected to the permanent magnet 3. The permanent magnet 3 is externally connected to the stationary iron core 4. The stationary iron core 4 is U-shaped and forms a gap with the moving iron core 2. The moving iron core 2 moves up and down along the connecting rod 1 between the two inner sides a and b of the stationary iron core 4.

[0024] The magnetic field generated by the permanent magnet 3 forms a closed loop in the gap between the moving iron core 2 and the stationary iron core 4 and generates a holding force on the moving iron core 2. The holding force is the maximum holding force when the moving iron core 2 moves to the inner sides a and b of the stationary iron core 4. The magnetic field distribution of the permanent magnet 3 at a and b is symmetrical.

[0025] like Figure 2 As shown, a method for designing parameters of a permanent magnet holding mechanism is innovative in that: based on the permanent magnet holding mechanism, a static magnetic field model of the permanent magnet holding mechanism is constructed based on finite element simulation to obtain the relationship curves between the maximum holding force and the radius of the moving iron core, and between the maximum holding force and the thickness of the permanent magnet; and the structural parameters of the permanent magnet holding mechanism are determined according to the maximum holding force requirement, wherein the structural parameters include the height of the moving iron core, the radius of the moving iron core, the height of the permanent magnet, and the thickness of the permanent magnet.

[0026] according to The principle determines the height of the moving iron core, where: R is the radius of the connecting rod, d is the thickness of the moving iron core, and σ is the height of the moving iron core. s F represents the yield strength of the moving iron core. em Maximum shear force;

[0027] The maximum holding force-moving iron core radius curve is obtained based on the static magnetic field model of the permanent magnet holding mechanism, as shown in the figure. Figure 3 As shown, the maximum holding force first increases and then decreases with the increase of the moving iron core radius. The moving iron core radius is determined to be the value corresponding to the highest point of the curve.

[0028] The height of the permanent magnet is the sum of the height of the moving iron core and the displacement of the moving iron core;

[0029] The maximum holding force-permanent magnet thickness curve was obtained based on the static magnetic field model of the permanent magnet holding mechanism, as shown in the figure. Figure 4 As shown, the maximum holding force increases rapidly at first and then gradually with the increase of the permanent magnet thickness. The thickness of the permanent magnet is determined based on the maximum holding force requirement.

[0030] The static magnetic field model established based on finite element simulation has the following simulation parameters: connecting rod radius R = 5mm, moving iron core displacement 5mm, maximum holding force requirement ~1kN, moving iron core height 10mm, moving iron core radius 14mm, permanent magnet height 15mm, and permanent magnet thickness 8mm. The holding force-displacement curve of the permanent magnet holding mechanism is shown below. Figure 5 As shown.

[0031] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A method for designing parameters of a permanent magnet holding mechanism, characterized in that: The permanent magnet holding mechanism includes a connecting rod (1), a moving iron core (2), a permanent magnet (3), and a stationary iron core (4). The moving iron core (2) is fitted on the connecting rod (1). The two ends of the moving iron core (2) are respectively connected to the permanent magnet (3). The permanent magnet (3) is externally connected to the stationary iron core (4). The stationary iron core (4) is U-shaped and forms a gap with the moving iron core (2). The moving iron core (2) moves up and down along the connecting rod (1) between the two inner sides a and b of the stationary iron core (4) under the drive of the connecting rod (1). The method is based on finite element simulation to construct a static magnetic field model of the permanent magnet holding mechanism, obtains the relationship curves between the maximum holding force and the radius of the moving iron core, and between the maximum holding force and the thickness of the permanent magnet, and determines the structural parameters of the permanent magnet holding mechanism according to the maximum holding force requirement. The structural parameters include the height of the moving iron core, the radius of the moving iron core, the height of the permanent magnet, and the thickness of the permanent magnet. according to The principle determines the height of the moving iron core, where: R is the radius of the connecting rod, d is the thickness of the moving iron core, and σ is the height of the moving iron core. s F represents the yield strength of the moving iron core. em Maximum shear force; The maximum holding force-moving iron core radius curve was obtained based on the static magnetic field model of the permanent magnet holding mechanism. The maximum holding force first increases and then decreases with the increase of the moving iron core radius. The moving iron core radius was determined to be the value corresponding to the highest point of the curve. The height of the permanent magnet is the sum of the height of the moving iron core and the displacement of the moving iron core; The maximum holding force-permanent magnet thickness curve was obtained based on the static magnetic field model of the permanent magnet holding mechanism. The maximum holding force increases rapidly at first and then gradually as the thickness of the permanent magnet increases. The thickness of the permanent magnet was determined according to the maximum holding force requirement.

2. The parameter design method for the permanent magnet retaining mechanism according to claim 1, characterized in that: The magnetic field generated by the permanent magnet (3) forms a closed loop in the gap between the moving iron core (2) and the stationary iron core (4) and generates a holding force on the moving iron core (2). The holding force when the moving iron core (2) moves to the positions of the inner sides a and b of the stationary iron core (4) is the maximum holding force. The magnetic field distribution of the permanent magnet (3) at a and b is symmetrical.

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