JPH05211760A - Magnetic circuit - Google Patents

Abstract

PURPOSE:To prevent the breakage of a magnetic circuit due to the collision, etc., of attracted foreign matters by covering permanent magnets or a yoke with a covering material. CONSTITUTION:A yoke 2 which has a pair of plate sections facing each other with a space in between and is long in the longitudinal direction of a vehicle is positioned below the bottom surface 1 of the vehicle. Permanent magnets 3 are firmly fixed to the internal surface of the yoke 2 in its length direction along the longitudinal direction of the vehicle. The magnets 3 are made of, for example, a rare-earth material, arranged so that their magnetic poles of different polarities can be faced to each other, and used as a driving-source field. A magnetic gap 4 of a prescribed width is formed between both magnetic poles. An armature coil 5 is fixed to the ground in the magnetic gap 4. A linear motor is constituted of the magnets 4 and coil 5. The vehicle is run along the coil 5 by the driving force of the linear motor. The magnets 3 are covered with a covering material 6. Therefore, the magnetic circuit thus constituted is not broken and no sound is produced even when foreign matters, etc., collide with the magnets 3 due to the attracting forces of the magnets 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic circuit using a permanent magnet, and more particularly to a magnetic circuit used for an on-vehicle field of a truck type linear motor car.

[0002]

2. Description of the Related Art Conventionally, various types of linear motor cars have been studied as a linear motor car that travels by using a linear motor to obtain propulsive force. One of them is to install a permanent magnet for a field on the vehicle. A linear synchronous motor using an armature coil arranged on the ground is known. Since this system places the main power supply side on the ground, it reduces the weight of equipment on the vehicle and is suitable for speeding up. As this kind of technology, for example, “JREA 1991 VOL.34 N
o. 1 ", JP-A-2-307355, and the like.

[0003]

In the above-mentioned prior art, since a large-sized rare earth permanent magnet is used as the permanent magnet for the field arranged in the vehicle, the amount of generated magnetism is extremely large. For this reason, there is a concern that the magnetic circuit may be damaged due to collision of foreign matter due to adsorption and cause noise.

Therefore, the present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to prevent damage to a magnetic circuit and generation of noise due to collision of foreign matter due to adsorption. is there.

[0005]

In order to achieve the above object, the invention of claim 1 has a pair of flat plate portions arranged in a vehicle and facing each other with a space therebetween, and is long in the front-rear direction of the vehicle. In a magnetic circuit having a yoke and a permanent magnet fixed so that magnetic poles of different polarities face each other on the inner side in the longitudinal direction of the yoke in the longitudinal direction of the vehicle, the periphery of the permanent magnet is covered with a covering material. It was Further, in the invention of claim 2, the coating material is formed of metallic copper or copper alloy.
According to the invention of claim 3, a yoke arranged in the vehicle, having a pair of flat plate portions facing each other with a space therebetween, and long in the front-rear direction of the vehicle, and a length of the yoke along the front-rear direction of the vehicle. In a magnetic circuit having a permanent magnet fixed such that magnetic poles of opposite polarities face each other inward in the direction, the yoke is covered with a covering material. Further, in the invention of claim 4, the coating material is formed of metallic copper or copper alloy.
Further, in the invention of claim 5, as the copper alloy, Cd-
A Cu alloy was used.

[0006]

According to the invention of claim 1 or 3, since the periphery of the permanent magnet or the yoke is covered with the coating material, it is possible to prevent the damage of the magnetic circuit and the generation of noise due to the collision of foreign matter due to the attraction. It will be possible. Here, as a property of the covering material, not only the mechanical strength is high, but also the flow of magnetic force lines in the magnetic circuit portion is not disturbed. As a material having such a property, for example, non-magnetic material such as austenitic stainless steel or aluminum can be considered. However, with these materials, eddy currents are generated by the lines of magnetic force, and heat is generated due to the electric resistance value of the materials. As a material for preventing the generation of the eddy current, a resin such as Delrin, polyimide, or polyamide, which is an insulator, can be considered, but its mechanical strength is inferior to that of metal. Therefore, in the invention of claim 2 or claim 4, as a material having a small amount of heat generation by eddy current and a large mechanical strength, attention is paid to metal copper or alloy copper, and the coating material is formed of metal copper or copper alloy. did. In the invention of claim 5, since the Cd-Cu alloy is used as the copper alloy,
It is possible to improve the mechanical strength without significantly lowering the electrical conductivity.

[0007]

Embodiments of the present invention will be described with reference to the drawings. Figure 2
FIG. 3 is a diagram showing a cross section of a magnetic circuit to which the present invention is applied. Under a floor surface 1 of a vehicle such as a linear motor car or an electric vehicle, a yoke 2 having a pair of flat plate portions facing each other across a space and long in the front-rear direction of the vehicle is arranged. The yoke 2 is made of iron, steel or the like. A permanent magnet 3 is fixed to the inside of the yoke 2 in the longitudinal direction along the vehicle front-rear direction. The permanent magnet 3 is made of, for example, a rare earth material, and is arranged so that magnetic poles of different polarities face each other.
Used as the field of the driving source.

A magnetic gap 4 having a predetermined gap is formed between both magnetic poles. An armature coil 5 fixed to the ground is arranged in this magnetic gap 4. A linear motor is constituted by the permanent magnet 3 and the armature coil 5, and the vehicle is driven by the propulsive force obtained by the linear motor.
It runs along the armature coil 5. The shape of the yoke 2 is
The shape is not limited to the above, and may be another shape such as a horseshoe shape or a flat plate facing shape.

FIG. 1 is a diagram showing an embodiment of the present invention, showing only one side of the yoke 2 in FIG. In this embodiment, a covering material 6 is provided around the permanent magnet 3. As a result, even if a foreign matter or the like directly collides with the permanent magnet 3 due to the attraction force of the permanent magnet 3, the permanent magnet 3 will not be damaged or generate noise.

Next, another embodiment of the present invention is shown in FIG.
This figure also shows only one side of the yoke 2 in FIG. In this embodiment, the covering material 6 is provided around the yoke 2. As a result, even if foreign matter or the like collides with the yoke 2 formed of iron, steel, or the like due to the attractive force of the permanent magnet 3, the magnetic circuit is not damaged or noise is not generated.

Next, the materials used for the covering material 6 shown in FIGS. 1 and 3 will be described in detail. As described above, the coating material 6 is required to have not only high mechanical strength but also to not disturb the flow of magnetic force lines in the magnetic circuit section. As a material having such properties, for example, austenitic stainless steel which is a non-magnetic material,
Or there is aluminum. However, with these materials, eddy currents are generated by the lines of magnetic force, and heat is generated due to the electric resistance value of the materials. As a material for preventing the generation of the eddy current, a resin such as Delrin, polyimide, or polyamide, which is an insulator, can be considered, but its mechanical strength is inferior to that of metal.

Therefore, in the present invention, as a material having little loss and heat generation due to eddy current and large mechanical strength,
Attention was paid to metallic copper (Cu). This is because metallic copper has a small specific magnetic susceptibility of −9.7 × 10 ^−6, is a diamagnetic material (non-magnetic material), and its electrical resistivity is standard annealed copper. This is because it is remarkably small at 1.7241 μΩ.cm.

Further, in the present invention, a copper alloy based on copper (Cu) is used as the coating material 6. FIG. 4 shows a change in electrical resistivity when a specific element is added based on copper. This is a graph showing the effect of the additive element on pure copper (OFE) on the electrical resistance. The horizontal axis of this graph is the amount of addition of the element (wt%), and the vertical axis is the electrical resistance (uΩ.cm 2). The electrical resistivity increases with the amount of copper added, but the value is, for example, 70% for stainless steel.
Compared with ~ 80μΩ.cm, it can be seen that it is smaller than an order of magnitude.

The properties of various copper alloys having excellent properties as the coating material 6 will be described below. First, the Cd-Cu alloy containing about 1% of Cd does not significantly lower the electric conductivity by the low temperature annealing and the mechanical strength is improved.
Zr (0.1 wt%)-Cu alloy has pure C electrical conductivity.
It is about 90 to 95% of u, but the heat resistance is 300 ° C.
Improves to about 1.3 times that of Cu.

Cu-Be (0.5Be, 2.5Co) alloy is a typical one showing a precipitation effect, and by hardening treatment, it is excellent in fatigue resistance and corrosion resistance, and has improved mechanical strength and electrical conductivity. The degree is also improved. Considering economy
The dispersion-strengthened alloy in which Fe fine particles of 2.3% or less are dispersed has high strength and appropriate electric conductivity. To improve heat resistance, Sn and Co may be added. Among the Cu-Zn alloys, 94-96Cu and 5Zn alloys have a low electric conductivity of 2.96 μΩ.cm and a high steel ratio.

Cu—Sn phosphorous bronze contains 0.05 to 0.25% of P as a deoxidizing agent. 5-8% Sn-Cu is economical. Others, Cu-Ni system, C
The u-Ni-Zn system also has excellent properties. in this way,
An alloy obtained by appropriately adding the elements shown in FIG. 4 to copper (Cu) is
It has excellent properties as a coating material. In the present invention, such an alloy is used as the covering material 6 shown in FIG. 1 or FIG. This reduces heat generation due to eddy currents, and
The mechanical strength can be increased.

[0017]

According to the present invention, since the periphery of the permanent magnet or the yoke is covered with the covering material, it is possible to prevent the magnetic circuit from being damaged and the noise from being generated due to the collision of foreign matters and the adsorption of iron pieces. Furthermore, since metallic copper or alloy copper is used as the coating material, heat generation due to eddy current can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a cross section of a magnetic circuit to which the present invention is applied.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a graph showing changes in electrical resistivity when various elements are added based on copper.

[Explanation of symbols]

 1 Floor surface 2 Yoke 3 Permanent magnet 4 Magnetic air gap 5 Armature coil 6 Coating material

Claims (5)

[Claims] 1. A yoke which is arranged in a vehicle and has a pair of flat plate portions facing each other across a space and which is long in the front-rear direction of the vehicle, and on the inside of this yoke in the longitudinal direction along the front-rear direction of the vehicle. A magnetic circuit having a permanent magnet fixed such that magnetic poles of opposite polarities are opposed to each other, wherein the periphery of the permanent magnet is covered with a covering material. 2. The magnetic circuit according to claim 1, wherein the coating material is metallic copper or a copper alloy. 3. A yoke which is arranged in a vehicle and has a pair of flat plate portions opposed to each other across a space and which is long in the front-rear direction of the vehicle, and on the inside of the yoke in the longitudinal direction along the front-rear direction of the vehicle. A magnetic circuit having a permanent magnet having magnetic poles of opposite polarities fixed to face each other, wherein the yoke is covered with a covering material. 4. The magnetic circuit according to claim 3, wherein the coating material is metallic copper or a copper alloy. 5. The magnetic circuit according to claim 4, wherein the copper alloy is a Cd—Cu alloy.