JPS5970172A - Magnet type dc machine - Google Patents

Abstract

PURPOSE:To improve the irreversible demagnetization resistance by enabling to effectively and safely magnetize the thickness of the upper circumferential end of a permanent magnet. CONSTITUTION:The outer diameter circumferential side end of a permanent magnet 9 contacted with a yoke 10 is disposed at least at the outside from the extension of a radial line OC for coupling the center of a stator 7 to the inner circumferential side end C of the magnet 9. The stator 7 is formed by securing an auxiliary pole 8 and the magnet 9 to the yoke 10. A rotor 11 is formed of a toothed part 12 and a grooved part 13, and an armature coil 14 is arranged on the part 13.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the shape of a permanent magnet fixed to the stator of a magnetic DC machine, and particularly relates to a magnetic DC machine in which the shape of the permanent magnet is improved to improve irreversible demagnetization resistance. Regarding the shape of the machine's permanent magnet.

A conventional permanent magnet for a magnetic DC machine generally has a shape as shown in FIG.

In Fig. 1, the shape of the permanent magnet 1 formed by press-molding magnetic powder is such that the magnetic powder surrounded by an outer frame 2 is press-molded by an upper bench 3 and a lower bench 4, so that the end face 5 in the circumferential direction is aligned with the center line of the magnet. The batting surface was f for OA. For this reason, when a strong demagnetizing field and a magnetizing field are applied to the circumferential ends of the circumference with the center of the magnet as a boundary due to the magnetic reaction during operation, the thick permanent magnet is advantageous in terms of reversible demagnetizing strength. , the thickness t of the line 08 connecting the outer peripheral end of the yoke side magnet and the center,
However, the thickness tl of the line 00 connecting the inner diameter side end of the magnet and the center line is thin, and the end has a structural defect that the demagnetization resistance is weak. Furthermore, even in magnetizing the permanent magnet 1, the corner portion 6 of the inner diameter 11111 had the disadvantage that effective magnetization was not performed.

The present invention has been made in view of the above-mentioned facts, and it is an object of the present invention to provide a magnetic DC machine having a stator with improved permanent magnet shape and improved irreversible demagnetization resistance.

The present invention is an extension of the radiation connecting the outer circumferential end of the permanent magnet that is in contact with the yoke to the stator center and the inner circumferential end of the permanent magnet in a magnetic DC machine that supports permanent magnets. The thickness of the magnet at the upper end of the cylinder of the permanent magnet, where the demagnetizing field due to armature reaction acts most strongly, is effectively thickened and completely magnetized by placing the magnet at least on the outside. It is.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnet type DC machine according to the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view showing essential parts of the rotor and stator. The stator 7 is formed by fixing auxiliary magnetic poles 8 and permanent magnets 9 to a yoke 10. The rotor 11 has teeth 12 and grooves 13.
An armature coil 14 is disposed in the sieve portion 13. Further, the permanent magnet 9
is the center O, whose end on the demagnetizing field side is an extension of the line OC connecting the center O of the stator 7 and the inner diameter end C of the permanent magnet.
The line OB connecting the yoke side permanent magnet end B and the yoke side permanent magnet end B is formed so that it is at least as far outside as or more than that.

The operation of the present invention configured as described above will be explained with reference to the analytical diagram of FIG.

It is well known that the irreversible demagnetization resistance of a permanent 4m stone is better when permanent magnets with the same magnetic properties are thicker. This is also clear from the following equation.

Here, ΔAT: Reverse T: Force, Mt: Permanent magnet thickness, Gt:
Gap length, a: electric machine, number of child parallel circuits, Z: armature current,
P: number of poles, ψ: pole enclosure.

When a high current flows through the armature coil 14, the state in which the magnetic flux passes due to the armature reaction is determined by the auxiliary magnetic pole 8 being the main magnet, and the permanent magnet on the demagnetizing field side having the teeth. Since the counter-electromotive force P from the part 12 and the counter-electromotive force P from the direction of the permanent magnet 1Ill are added,
In reality, a larger counter-electromotive force acts than the value obtained by equation (1). In particular, S @ using an anisotropic magnet, it is possible to obtain a high coercive force in the direction of the inner and outer cylinders of the magnet, but the direction perpendicular to the anisotropy, in this case P, force direction t1m force is in the anisotropic direction. Because it is as small as 172 to 1/3 of
The width of the permanent magnet is made wider than above the OC line, the thickness is increased in the direction in which the counter-electromotive force is applied, and the part that is difficult to completely magnetize as in the past is eliminated, so that the entire permanent magnet is completely magnetized.
A high coercive force can be obtained against a demagnetizing field in the Pt direction.

Further, regarding the shape of the permanent magnet 9, linear grinding is performed so that the inner and outer diameters are machined and the side faces are machined at the same time, so that the cost does not increase.

As described above, in the shape of a permanent magnet for a DC machine field, the outer circumferential end of the permanent magnet that is in contact with the yoke is
so that it is at a position at least outside the extension of one line connecting the stator center and the inner circumferential end of the permanent magnet,
Since the thickness of the upper end of the circumference of the permanent magnet is effectively thickened and can be completely magnetized, it has a high resistance to the linear magnetomotive force, which is the sum of the counter-electromotive force from the side surface and the counter-electromotive force from the toothed area. This has the effect of greatly improving irreversible demagnetization resistance.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional ηi diagram showing the shape and manufacturing method of a conventional permanent magnet.
FIG. 2 is a sectional view showing a main part of a magnetic circuit according to an embodiment of the magnetic DC machine according to the present invention, and FIG. 3 is an analysis diagram of the flow of magnetic flux shown in FIG. 2 obtained by the finite element method. 1.9... Permanent magnet, 7... Stator, 8... Auxiliary magnetic pole, 10... Yoke, 11... Rotor, 12...
Tooth portion, 13... Groove portion, 14... Armature coil.

Claims (1)

[Claims] 1. In a magnetic direct current machine with permanent magnets, the demagnetizing field side of the armature reaction of the circumferential end of the permanent magnet in contact with the yoke is the center of the stator and the inner circumferential end of the permanent magnet. A magnet-type DC machine that has a stator with a fixed permanent magnet formed at least on the outside to extend the radiation that connects the .