JPS6043051A - Flat type synchronous rotary electric machine - Google Patents

Abstract

PURPOSE:To reduce an irregular torque by forming a yoke of sector shape for forming a rotor field in the specific shape. CONSTITUTION:A stator 11 secured to a case 16 is wound with a winding 12 radially at an annular core. A shaft 17 mounted in the case 16 through bearings 18 has a rotor 13, a plurality of permanent magnets 14 are secured to the rotor 13, a yoke 15 is secured as a pole, thereby forming a flat type synchronous rotary electric machine. The yoke 15 is, if the number of the poles is 4, in a sector shape having 90 deg. (180 deg. of electic angle) of an angle AOB, and in a profile having an arcuate 20 of radius r1, linear lines 21, 22 and a sinusoidal curve 23. In this case, the curve 23 is formed so that the radial size (l) is a value proportional to the sine (sin 2theta in the drawings) to the electric angle. The radius r1 is equal to the outer diameter of the annular core of the stator 11, and the radius r2 is equal to the inner diameter. Thus, a magnetic flux distribution becomes a sinusoidal wave.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a flat type synchronous rotating electric machine having an axial gap as a main magnetic path, and particularly to the shape of rotor magnetic poles.

BACKGROUND OF THE INVENTION With the expansion of the field of use of synchronous motors (for example, applications as AC boobo motors, etc.), there is an increasing demand for thinner motors, that is, shorter axial dimensions. In a typical synchronous motor whose main magnetic path is a gap in the radial direction, if the axial length is shortened, the ratio of leakage magnetic flux increases, making it impossible to obtain a high efficiency motor. Therefore, a system in which the axial gap is used as the main magnetic path has come to be adopted.

A synchronous rotating electric machine with an axial gap as the main magnetic path has the same function as a general synchronous rotating electric machine with the stator and rotor field facing each other with an axial gap in between, and the radial gap as the main magnetic path. fulfill. In particular, even if the structure is made flat, there is little decrease in efficiency and it is suitable when there is a restriction on the arrangement space. The stator is provided with windings and supplied with current to produce a rotating magnetic field. A field pole is formed on the rotor by a permanent magnet and a yoke, and the field pole receives a rotational force from the rotating magnetic field of the stator, causing the rotor to rotate.

However, the above-mentioned synchronous rotating electric machine in which the axial gap is used as the main magnetic path has a problem in that torque unevenness occurs when it is used as an actuator of a control device and performs highly accurate control. It is known that in order to reduce torque unevenness, the amount of flux linkage in the stator windings must be sinusoidal. Conventionally, the optimal shape of the rotor magnetic poles to accommodate this is as follows: The reality is that nothing satisfactory has yet been achieved.

OBJECTS OF THE INVENTION In view of the above-mentioned problems in synchronous rotating electric machines, an object of the present invention is to create a chain from the rotor magnetic poles to the stator windings based on the idea of making the shape of the yoke constituting the rotor magnetic poles sinusoidal. The purpose is to make the distribution of intersecting magnetic fluxes sinusoidal, thereby reducing torque unevenness in a synchronous rotating electric machine.

Composition of the Invention In the present invention, in a flat type synchronous rotating electrical machine having a main magnetic path with a gap in the direction of the arrow, a plurality of permanent magnets are provided, and a space between the permanent magnets and the stator is such that the permanent magnets face the stator with a slight gap therebetween. It is fixed to the permanent magnet and includes a rotor field having a fan-shaped yoke. There is provided a flat type synchronous rotating electrical machine characterized in that the radial dimension of the portion facing the stator takes a value substantially proportional to the sine of each electrical angle.

Embodiment FIG. 1 is a sectional view showing the structure of a flat type synchronous rotating electric machine as an embodiment of the present invention. The stator 11 has an annular iron core and windings 12 are wound radially. Stator 11
is fixed to the case 16.

A rotor 13 has a shaft 17 and is attached to a case 16 via a bearing 18. A plurality of permanent magnets 14 are fixed to the rotor 13, and a yoke 15 as a magnetic pole is fixed to the permanent magnet 14°, and the yoke 15 and the stator 11 face each other with a small gap between them. (7) This gap becomes the main magnetic path of this rotating electrical machine. When a power source is connected to the winding 12 of the stator 11 and a rotating magnetic field is generated in the stator 11, the rotor 13 rotates accordingly.

FIG. 82 shows a plan view of the rotor 13. This example shows a case where the number of poles is 4, and the yoke 15 is alternately N and S.
Become the pole. The permanent magnet 14 is not shown in FIG. 2 because it is covered by a yoke 15.

FIG. 3 shows the shape of at least the portion of the yoke 15 that is close to and opposes the stator 11. Arc 20 with radius rl
, the straight line 21.22, and the sinusoidal curve 23.
The shape of JJ' becomes the outer shape of the yoke. The arc 200 radius rl is equal to the outer shape of the annular core of the stator 11, and the curve 2
The radius r2 of the circular arc 24 that 3 is in contact with is equal to the inner diameter of the annular core. In this example, since the number of poles is four, the angle AOB is 90 degrees, and this 90 degrees corresponds to an electrical angle of 180 degrees. If the number of poles is N, the angle AOB is 360/N degrees, and this angle corresponds to an electrical angle of 180 degrees. One point C of arc 20
Let D be the point where the straight line connecting center 0 of the circle of arc 20 intersects curve 23, and let the length of straight line CD be 4, then l = (rl-r2) 8111 (-T-°θ)
becomes. Here, np is the number of poles, and θ is the angle BOC.

In addition, ¥·θ indicates an electrical angle, and both ends of the approximately fan-shaped shape drawn as shown above are cut off by straight lines 21 and 22 to form the outer shape of the yoke. Straight lines 21 and 22
have an angle of approximately 10 degrees with respect to straight lines OA and OB, respectively. By removing both ends, the rotor 13
Mainly when arranging yokes, contact between adjacent yokes can be avoided.

FIG. 4 shows a plan view of the yoke 15 formed as described above, and FIG. 5 shows a side view thereof. The shape of the yoke 15 as described above is such that only the part of the yoke 15 facing the stator via the main magnetic path needs to follow this shape, and the part that contacts the permanent magnet 14 should cover the entire surface of the permanent magnet 14 as much as possible. It is formed.

In this embodiment, by making the shape of the yoke 15 constituting the magnetic poles of the rotor 13 sinusoidal, the permanent magnet
4 can be distributed in a sinusoidal manner, thereby making it possible to distribute the magnetic flux interlinking with the stator winding 12 of the magnetic poles in a sinusoidal manner.

Effects of the Invention According to the present invention, the distribution of magnetic flux interlinking with the stator windings from the rotor magnetic poles can be made sinusoidal, thereby reducing torque unevenness in a synchronous rotating electric machine.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a flat type synchronous rotating electric machine as an embodiment of the present invention, FIG. 2 is a plan view of a rotor in the flat type synchronous rotating electric machine of FIG. 1, and FIG. FIG. 4 is a plan view of the yoke, and FIG. 5 is a side view of the yoke shown in FIG. 4. DESCRIPTION OF SYMBOLS 11... Stator, 12... Winding, 13... Rotor, 14... Permanent magnet, 15... Yoke, 16...
Case, 17... shaft, 18... bearing.

Claims (1)

[Claims] In a flat type synchronous rotating electrical machine whose main magnetic path is an axial gap, there are a plurality of permanent magnets, and a magnet fixed to the permanent magnets so as to face the stator with a slight gap between the permanent magnets and the stator. A rotor field having a fan-shaped yoke is provided, and the fan-shaped yoke has a radial direction of at least a portion of the sector facing the stator when the central angle of the sector is expressed as an electrical angle. A flat type synchronous rotating electric machine characterized in that the dimensions of are approximately proportional to the sine of each electrical angle.