JPH05284720A - Magnetic circuit - Google Patents

Abstract

PURPOSE:To avoid the corrosion of a permanent magnet by a method wherein the circumference of a coated permanent magnet and a yoke is further coated with a coating film (CS). CONSTITUTION:A first layer coating film (CS) 6 is applied to the circumference of a permanent magnet 3. The permanent magnet coated with the CS 6 is bonded to a yoke 2 with a bonding layer 7. A second layer CS 8 is applied to the circumference of the permanent magnet 3 coated with the CS 6 and the yoke 2. The CS and the CS 8 may be made of the same material or different materials. If different materials are employed, the CS 6 is made of material which has a high bonding strength to both the permanent magnet 3 and the yoke 2 and then the CS 8 is made of material which can be elastically deformed, i.e., resin. As the CS 8 absorbs strain produced in the bonding layer 7, crackings produced in a coating part A between the lower corner part of the permanent magnet 3 and the yoke 2 can be avoided, so that the permanent magnet 3 can be protected from corrosion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic circuit, and more particularly to a magnetic circuit used for the on-vehicle field of a carriage 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. As one of them, a permanent magnet for a field is arranged in the vehicle. However, there is known one using a linear synchronous motor in which an electric coil is arranged on the ground. 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 VO
L. 34 No. 1 ", JP-A-2-307355, and the like.

[0003]

SUMMARY OF THE INVENTION In the above prior art, Nd-Fe-B is used as a permanent magnet for a field arranged in a vehicle.
System magnets are often used. However, this Nd-F
The e-B type magnet is easily corroded. Therefore, in order to prevent the corrosion of the permanent magnet, conventionally, the periphery of the permanent magnet is coated with a coating film such as plating. The coated permanent magnet is adhered to the yoke. However, due to the difference in coefficient of thermal expansion between the yoke and the permanent magnet, a crack (crack) occurs in the coating between the lower corner of the permanent magnet and the yoke. However, there was a problem that the corrosion resistance of the product deteriorated.

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 corrosion of a permanent magnet attached to a yoke.

[0005]

In order to achieve the above object, according to the first aspect of the invention, a yoke arranged in a vehicle, having a pair of flat plate portions opposed to each other with a space in between, and long in the front-rear direction of the vehicle. And a permanent magnet fixed such that magnetic poles of different polarities face each other on the inner side of the yoke in the longitudinal direction along the front-rear direction of the vehicle, the first magnetic circuit coating the periphery of the permanent magnet. It has a coating film and a second coating film that coats the permanent magnet coated with the first coating film and the periphery of the yoke. Further, in the second invention, the first coating film and the second coating film are made of the same material. Further, in the third invention, the permanent magnet is an R—Fe—B system magnet (R: one or more rare earth elements such as Nd and Pr), and the yoke and the permanent magnet have a coefficient of thermal expansion. Further, the second coating film is formed of an elastically deformable material and absorbs the strain generated in the adhesive layer between the yoke and the permanent magnet. Further, in the fourth aspect of the present invention, the pair of flat plate portions arranged in the vehicle and facing each other through a space are provided,
And a yoke that is long in the front-rear direction of the vehicle, and a plurality of permanent magnets fixed inside the yoke in the longitudinal direction along the front-rear direction of the vehicle such that magnetic poles of opposite polarities face each other along the front-rear direction of the vehicle. In a magnetic circuit having a magnet and a plurality of screws that are inserted between a plurality of permanent magnets fixed along the front-rear direction of the vehicle and screwed into a yoke, a first circuit that coats the periphery of the permanent magnet is provided. It has a coating film and a second coating film that coats the permanent magnet coated with the first coating film, the screw and the periphery of the yoke.

[0006]

According to the first invention, the circumference of the permanent magnet and the yoke coated with the first coating film is
Furthermore, since it is coated with the second coating film,
The coating between the lower corner of the permanent magnet and the yoke is coated in two layers, and even if the yoke and the permanent magnet have different coefficients of thermal expansion, there is a gap between the lower corner of the permanent magnet and the yoke. Cracks are less likely to occur in the coating part of. This makes it possible to prevent corrosion of the permanent magnet. Furthermore, in the second invention, since the first coating film and the second coating film are formed of the same material, the manufacturing process is simplified and extra equipment is not required. Further, in the third invention, since the second coating film is made of an elastically deformable material, the adhesive layer between the yoke and the permanent magnet is different due to the difference in thermal expansion coefficient between the yoke and the permanent magnet. This second coating film absorbs the distortion caused by. As a result, cracks are less likely to occur in the coating portion between the lower corners of the permanent magnet and the yoke, and in particular, R-Fe-B based magnets (R: Nd, Pr or other rare earth element 1) that easily corrode. It is possible to effectively prevent corrosion of more than one kind). Furthermore, the fourth
According to the invention described above, by inserting the screw between the plurality of permanent magnets, it becomes possible to effectively prevent corrosion of the permanent magnets in the magnetic circuit of the type in which the yoke and the plurality of permanent magnets are fixed.

[0007]

Embodiments of the present invention will be described with reference to the drawings. Figure 3
FIG. 3 is a diagram showing a cross section of a linear motor to which the present invention is applied. A yoke 2 is arranged below a floor surface 1 of a vehicle such as a linear motor car or an electric vehicle. This york 2
Has a substantially U-shaped cross-section with a lower opening and is formed of a high-permeability iron plate or the like that is long in the front-rear direction of the vehicle. A permanent magnet 3 is fixed to the inside of the yoke 2 in the longitudinal direction along the vehicle front-rear direction. A plurality of permanent magnets 3 are fixed along the longitudinal direction of the vehicle. And this permanent magnet 3
Are arranged so that the magnetic poles of opposite polarities face each other and are used as the field of the drive source. The shape of the yoke 2 is not limited to the U-shape, but may be another shape such as a horseshoe shape.

A magnetic gap 4 having a predetermined gap is formed between both magnetic poles. The grounded armature coil 5 is arranged in the magnetic gap 4. The permanent magnet 3 and the armature coil 5 constitute a linear motor, and the vehicle travels along the armature coil 5 by the propulsive force obtained by the linear motor.

As the permanent magnet 3, an R-Fe-B system magnet (R: one or more rare earth elements such as Nd and Pr) having high magnetic properties is used. This R-Fe-B magnet is particularly prone to corrosion. Therefore, in the present invention, as shown in FIG. 1, the permanent magnet 3 and the yoke 2 are coated with a coating film. First, in order to prevent corrosion of the permanent magnet 3, a coating film 6 of the first layer is coated around the permanent magnet 3. The permanent magnet 3 coated with the first layer coating film 6 is
It is bonded to the yoke 2 via the adhesive layer 7. A second layer coating film 8 is coated around the permanent magnet 3 and the yoke 2 coated with the first layer coating film 6.

The first layer coating film 6 and the second layer coating film 8 may be made of the same material or different materials. If they are made of the same material, the manufacturing process is simple and no extra equipment is required.
When the first layer coating film 6 and the second layer coating film 8 are formed of different materials, first, the first layer coating film 6 is adhered to both the permanent magnet 3 and the yoke 2. It is made of a strong material. As the material having high adhesion strength, for example, plating (Ni, Cr, S
n, Au, Ag, etc.). The thickness of the plating may be 1 μm or more, but if it is too thin, pinholes are likely to occur.

Next, the second layer coating film 8 is formed of an elastically deformable material such as resin. As such resin, for example, epoxy resin (thickness 12 to 24 μ
m), acrylic resin, etc. Further, the second layer coating film 8 may be formed by a vacuum deposition film. The thickness of this resin may be 1 μm or more, but if it is too thin, pinholes are likely to occur.
Is preferable (especially, 10 to 30 μm is most preferable).

In particular, an elastically deformable material is used as the second coating film 8 because the yoke 2 and the permanent magnet 3 have different thermal expansion coefficients.
This is to absorb the strain generated in the adhesive layer 7 between and.
For example, in the case of a steel yoke, its coefficient of thermal expansion is 1.
1 × 10 ⁻⁵ (cm / cm / ° C.), for example, Nd−
In the case of an Fe-B based permanent magnet, its coefficient of thermal expansion is 1.
It is 4 × 10 ⁻⁵ (cm / cm / ° C.). In this way, the second layer coating film 8 formed of an elastically deformable material absorbs the strain generated in the adhesive layer 7, so that the coating between the lower corner portion of the permanent magnet 3 and the yoke 2 is performed. It is possible to prevent cracks from occurring in the portion (dotted line portion A in FIG. 1), and as a result, to prevent the permanent magnet 3 from corroding.

In this method of forming a magnetic circuit, first, a coating film 6 for the first layer is coated around the permanent magnet 3, and then the permanent magnet 3 after the coating film 6 for the first layer is coated. To the yoke 2. Then, finally, the periphery of the permanent magnet 3 and the yoke 2 after being coated with the first layer coating film 6 is coated with the second coating film 8.

Next, coating of another magnetic circuit will be described with reference to FIG. As shown in FIG. 2, the screw 9 is inserted into the gap between the permanent magnet 3 a and the permanent magnet 3 b and screwed into the yoke 2. As a result, the yoke 2 and the permanent magnets 3a and 3b are mechanically fixed. A first coating film 6 is coated around the permanent magnets 3a and 3b. As the material of the first coating film 6, it is preferable to use a material having high mechanical strength so as to withstand mechanical fixation. The second layer coating film 8 is coated around the permanent magnets 3a and 3b, the screw 9 and the yoke 2 which are coated with the first layer coating film 6. As a material for the coating film 8, an epoxy resin, a vacuum deposition film, or the like is suitable.

In this magnetic circuit forming method, first, a coating film 6 of a first layer is coated around the respective permanent magnets 3a and 3b, and then, between the coated permanent magnets 3a and 3b. A screw 9 is inserted into the gap, and the screw 9 is screwed into the yoke 2. As a result, the permanent magnets 3a and 3b are mechanically fixed to the yoke 2. On this occasion,
Further, the yoke 2 and the permanent magnets 3a and 3b may be bonded with an adhesive. And finally, the permanent magnets 3a, 3 after being coated with the coating film 6 of the first layer
The second coating film 8 is coated around b, the screw 9, and the yoke 2.

[0016]

According to the first aspect of the present invention, the periphery of the permanent magnet and the yoke coated with the first coating film is further coated with the second coating film. The coating part is coated in two layers, and even if the yoke and the permanent magnet have different coefficients of thermal expansion, cracks are less likely to occur in the coating part between the corner of the permanent magnet and the yoke, preventing corrosion of the permanent magnet. can do. Furthermore, in the second invention, since the first coating film and the second coating film are formed of the same material, the manufacturing process is simplified and extra equipment is not required. Further, in the third invention, since the second coating film is made of an elastically deformable material, the adhesive layer between the yoke and the permanent magnet is different due to the difference in thermal expansion coefficient between the yoke and the permanent magnet. This second coating film absorbs the distortion caused by.
As a result, cracks are less likely to occur in the coating portion between the corners of the permanent magnet and the yoke, and in particular, corrosion of the Nd-Fe-B magnets, which easily corrode, can be effectively prevented. Further, in the fourth invention, by inserting the screw between the plurality of permanent magnets, it is possible to effectively prevent the corrosion of the permanent magnets in the magnetic circuit of the type that fixes the yoke and the plurality of permanent magnets. it can.

[Brief description of drawings]

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

FIG. 2 is a diagram showing another embodiment of the present invention.

FIG. 3 is a diagram showing a cross section of a linear motor to which the present invention is applied.

[Explanation of symbols]

 2 yoke 3 permanent magnet 6 first coating film 7 adhesive layer 8 second coating film 9 screw

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. In a magnetic circuit having a permanent magnet fixed so that magnetic poles of opposite polarities face each other, a first coating film coating the periphery of the permanent magnet, a permanent magnet coated with the first coating film, and the above A second coating film coating the periphery of the yoke, the magnetic circuit. 2. The magnetic circuit according to claim 1, wherein the first coating film and the second coating film are made of the same material. 3. The permanent magnet is an R—Fe—B based magnet (R: one or more rare earth elements such as Nd and Pr),
The yoke and the permanent magnet have different thermal expansion coefficients, and further, the second coating film is formed of an elastically deformable material, and strain generated in the adhesive layer between the yoke and the permanent magnet. The magnetic circuit according to claim 1, wherein the magnetic circuit absorbs. 4. 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 the yoke in the longitudinal direction along the front-rear direction of the vehicle. A yoke which is inserted between a plurality of permanent magnets fixed so that magnetic poles of different polarities face each other along the front-rear direction of the vehicle and a plurality of permanent magnets fixed along the front-rear direction of the vehicle. A magnetic circuit having a plurality of screws screwed into a first coating film for coating the periphery of the permanent magnet, the permanent magnet coated with the first coating film, coating the periphery of the screw and the yoke And a second coating film for forming a magnetic circuit. 5. The permanent magnet is an R—Fe—B based magnet (R: one or more rare earth elements such as Nd and Pr),
The yoke and the permanent magnet have different thermal expansion coefficients, and further, the second coating film is formed of an elastically deformable material, and strain generated in the adhesive layer between the yoke and the permanent magnet. The magnetic circuit according to claim 4, wherein the magnetic circuit absorbs.