Single-stage, two-phase of four-phase synchronous electric motor

Details Single-stage, two-phase of four-phase synchronous electric motor Single-stage, two-phase of four-phase synchronous electric motor

1987-08-11

1989-04-18

Skudy, R.

Electrical generator or motor structure

Dynamoelectric

Rotary

310156, 310162, 310184, 310185, H02K 122

Patent

active

048230405

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to a single-stage, two-phase or four-phase synchronous electric motor of the type comprising a permanently magnetized disc-shaped rotor part as described, for example, in Swiss Pat. No. 637 508.
In the known single-stage, two-phase motors, the number of active poles of the stator assembly, i.e. the number of locations where the variable air-gap has a minimal height, is limited, phase-wise, to 40 % of the number of poles of like type appearing on each of the planar surfaces of the magnetised rotor part. This also limits the torque of the motor for a given number of ampere-turns of the corresponding control coils.
The purpose of the present invention is in particular to increase the torque of such a motor and to provide a motor, having a particularly simple and economic construction, which is of small dimensions, in which the number of active poles can be increased beyond the aforementioned limit.
The invention, its particular features and advantages will be better understood in the light of the following description which is given, by way of example, of two embodements which are illustrated by the accompanying drawing, in which:
FIG. 1 is an axial section, along the line I--I' of FIG. 2, of a two-phase motor according to the invention and comprising two pairs of coils,
FIG. 2 is a view from above of the lower stator part of the motor according to FIG. 1, and
FIG. 3 is a view from above, similar to that of FIG. 2, illustrating a modified form of the motor shown in FIGS. 1 and 2, comprising two coils surrounding the shaft of the motor.
The motor shown in axial section in FIG. 1 comprises a shaft 1 on which is fixed, by means of a support member 2, an annular disc-shaped member, for example, of samarium cobalt, forming a permanently magnetized rotor part. This rotor part is magnetised axially, so as to present, on each of its planar surfaces, 50 poles of like type disposed regularly along its annular surfaces and preferably alternating with 50 poles of opposite polarity. The rotor part 3 defines a first side and a second side (not identified) in the form of a flat annular disc having a first flat surface and a second flat surface (not identified).
The shaft 1 is rotatably mounted, by means of bearings 4, 5 shown diagrammatically in FIG. 1, in a stator assembly 6 which comprises two parts, namely, a lower stator part 7 and an upper stator part 8. These stator parts are made of a magnetically permeable material which, in the present example, is sintered iron. In the vicinity of the rotor part of the motor, these stator parts have pole parts such as 9, 10. In the present example, the polar parts of each stator part form four groups corresponding to four pole pieces designated by 11, 12, 13 and 14 for the lower stator part 7. The upper stator part 8 is of the same form as the part 7, with which it is united by screws such as 15. The assembled two stator parts thus present, along an annular zone in which is disposed the magnetised rotor part 3, an air-gap of which the height, i.e. the dimension in the axial direction, varies in passing from one pole part to the following. The different pole parts may have the form of teeth of rectangular or rounded section, the crests of the different teeth forming active poles of the stator part. In FIG. 2, these crests are represented disgrammatically by radially disposed chain-dotted lines.
In the case as represented in FIG. 2, each stator part comprises four projecting pole-pieces disposed in the four quadrants around the axis of the motor shaft and thus presents two perpendicular axial planes of symmetry. Two diametrically opposite groups are associated with a like phase of the two-phase motor of this example.
The stator assembly additionally comprises electric control coils--four coils in the present case--of which three (16, 17 and 18) are visible in FIGS. 1 and 2. As is shown more particularly in FIG. 2, on each side of the rotor part 3, i.e. in each stator part, two diametrically opposite pole-pieces are surrounded by coils, such as the coils

REFERENCES:
patent: 3539847 (1970-11-01), Gifford
patent: 4006375 (1977-02-01), Lyman
patent: 4031419 (1977-06-01), Spiesberger
patent: 4424463 (1984-01-01), Musil
patent: 4517478 (1985-05-01), Oudet
patent: 4518883 (1985-05-01), Oudet
patent: 4680494 (1987-07-01), Grosjean

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