JPS6321422B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a step motor having a stator winding of at least four phases.

Conventionally, if we take a step motor having a four-phase stator winding as an example, there have been two types of step motors in terms of structure.

That is, one of them is that one rotor having a large number of rotor teeth on the outer peripheral surface is provided on one rotor shaft, and eight stator convex poles protrude in the radial direction corresponding to the rotor. This is a step motor having a structure in which one stator is provided.

This type of step motor has been widely used in the past, but there are 8
Since it is necessary to arrange two convex stator poles, it is necessary to increase the diameter of the rotor, which has the drawback of increasing the inertia of the rotor.

The other method is to provide four rotors with a large number of rotor teeth on the outer circumferential surface on one rotor shaft, and two convex stator poles in the radial direction corresponding to each rotor. This is a step motor with a structure in which four stators are provided.

This type of step motor has an independent pair of rotor and stator for each phase, and only two stator convex poles are arranged around the outer circumference of one rotor, so the rotor diameter can be made small. Therefore, it has the advantage that the inertia of the rotor is generally smaller than that of the step motor.

However, since this type of step motor requires as many rotors as the number of phases, the sum of the inertia of each rotor cannot be said to be sufficiently small, and furthermore, the shape becomes long in the axial direction of the rotor. It had the following drawback.

SUMMARY OF THE INVENTION An object of the present invention is to provide a step motor that eliminates the above-mentioned conventional drawbacks.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIGS. 1 to 5, 1 is a rotor shaft;
Reference numerals 2 and 3 indicate first and second rotors formed by sintering a magnetic material, and a large number of rotor teeth are provided on the outer peripheral surfaces of the rotors. 4 is a cylinder made of a non-magnetic material such as aluminum and placed between the first and second rotors; 5 and 6 are made of fluororesin and have a cylinder at one end of the first and second rotors; It is a disc arranged.

First and second stators 7 and 8 are formed by sintering a magnetic material, and have four stator convex poles 9 to 12 and 13 to 16, respectively, in the radial direction. A plurality of stator teeth are formed on the tip surface of each stator convex pole. 17 to 20
are each stator convex pole 9 to 12 of the first stator 7
21 to 24 are stator windings wound around each stator convex pole 13 to 16 of the second stator 8 via a resin bobbin (however, , stator winding 2
2 and 24 are not shown in the drawings), 25 is a cylinder made of a non-magnetic material such as aluminum, and is disposed between the first and second stators 7 and 8;
and 27 are brackets made of aluminum and placed at the outer ends of the first and second stators 7 and 8, respectively; brackets 28 and 29 are made of sintered bronze and graphite as a solid lubricant; , 27, the bearing 30 is made of a non-magnetic material such as aluminum, and has four protrusions 31 on each side.
The spacers are provided with projecting portions 31 to 38 of the first and second stators 7 and 8.
The stator convex poles 9 to 12 and 13 to 16 are arranged to be located between the stator convex poles 9 to 12 and 13 to 16. The inner circumferential surface of this spacer 30 has stator convex poles 9 to 12 and 13.
These are flush with the bottoms of the stator teeth provided on the tip surfaces of the stator teeth 1 to 16. 39 is provided between each stator tooth and on the inner surface of the spacer 30, and is an epoxy resin mixed with aluminum powder; 40 is each stator winding wire 17 to 20 and 21 to 20 led out from a through hole bored in the bracket 27; 24 is a lead wire, and 41 is a packing for the through hole.

42 to 45 and 46 to 49 are protrusions provided on the brackets 26 and 27, respectively; 50 to 57 are protrusions provided on both sides of the cylindrical body 25; 58 to 65
and 66 to 73 are grooves provided on both sides of the first and second stators 7 and 8, respectively, and these protrusions 42 to 57 and grooves 58 to 73 engage with each other. 74 to 77 and 78 to 81 are screw holes provided in the brackets 26 and 27;
Screws 82 to 85 are passed through.

Next, the manufacturing process of the step motor having the above structure will be explained.

() Insert the cylinder 4, the first and second rotors 2, 3, and the discs 5, 6 into the rotor shaft 1, and the rotor teeth of the first and second rotors 2, 3 are set to one quarter of each other.
After positioning with a jig so as to shift the pitch, it is fixed to the rotor shaft 1 with adhesive. Thereafter, the outer peripheral surfaces of the rotor teeth are cut to give the outer diameters of the first and second rotors 2 and 3 a predetermined size.

() Stator windings 17 to 20 and 21 to 24 are wound around the first and second stators 7 and 8 via bobbins, a spacer 30 and a cylinder 25 are arranged between both stators 7 and 8, and After placing brackets 26 and 27 on the outside, screw 8
2 to 85, tighten the brackets 26 and 27 from both sides.

() The hole provided in the center of the bracket 26 and the stator convex poles 9 of the first and second stators 7 and 8
A rod having a shape that is in contact with the tip surfaces of 12 to 13 to 16 but not in contact with the hole provided in the center of the bracket 27 is inserted, and the aluminum powder and hardening agent are injected from between the rod and the hole in the bracket 27. Inject the mixed epoxy resin. Thereafter, the resin is cured by heating, and the rod is removed.

() Inner peripheral surface of the hole provided at the center of the brackets 26, 27, stator convex poles 9 to 12 and 13
The tip surfaces of 1 to 16 and the inner circumferential surface of the resin are broached at the same time, and each inner diameter is set to a predetermined size.

() After inserting the rotor assembly manufactured by the process in () above into the stator assembly, the bearing 2
Press in 8 and 29.

Next, the operation of the step motor manufactured by the above process will be explained with reference to FIG.

A pair of diametrically opposed stator convex poles 9 and 11 provided on the first stator 7 are convex poles for the A phase, and the same convex poles 10 and 12 are convex poles for the C phase. The stator teeth provided at 9 and 11 and the stator teeth provided at the C-phase convex pole are shifted by a half pitch. The stator convex poles 13 and 15 provided on the second stator 8 are for B phase, and the same convex poles 14 and 16 are for D phase, and the stator teeth provided on the B phase convex poles are The stator teeth provided on the D-phase convex pole are shifted by a half pitch. Further, the stator teeth of the A-phase convex pole and the B-phase convex pole are in phase, and the stator teeth of the C-phase convex pole and D-phase convex pole are in phase.

Therefore, when the pulse signals shown in FIGS. 6A to 6D are supplied from the lead wire 40 to the stator windings 17 to 24 wound around the convex poles for the A to D phases,
This step motor operates as a two-phase excitation motor and rotates in quarter pitch increments for each pulse signal (the excited windings are AB phase → BC phase → CD phase → DA phase, etc.).

As detailed above, the step motor of this embodiment includes two stators each having convex stator poles for different phases to form the stator side.
Since the structure has two rotors corresponding to each stator, the inertia of the rotor is lower than that of the conventional structure in which only one rotor is provided and eight stator convex poles for four phases are arranged around the outer circumference. Not only can this be made smaller, but also because the number of rotors is reduced by two compared to the conventional system in which four rotors are formed on the rotor shaft and four stators are provided corresponding to each rotor. The inertia of the rotor is reduced, and the overall shape of the motor can be further downsized.

In addition, in the case of two-phase excitation, the magnetic flux that comes out from the pair of stator convex poles in the first stator 7 and the second stator 8 and crosses the rotor in the diametrical direction passes through the outer periphery of the stator and enters the closed magnetic path. This closed magnetic path is magnetically independent for each stator 7, 8, so that interference and leakage of magnetic flux does not occur. Therefore, there is no need to install windings or control the direction of current application in consideration of the direction of the generated magnetic flux, making it easier to manufacture and control the step motor.

Although a four-phase step motor has been described in this embodiment, for example, a six-phase step motor may be provided with three rotors and each rotor has three convex stator poles for two phases on its outer periphery.
The effects of the present invention can also be obtained even if multiple stators are provided.

As described above, the present invention can provide a small-sized step motor with a small rotor inertia, and its industrial effects are great.

[Brief explanation of the drawing]

1 to 5 are diagrams showing one embodiment of the present invention, in which FIG. 1 is a sectional view of a step motor, and FIG.
3 is a stator assembly diagram, FIG. 3 is a rotor assembly diagram, FIG. 4 is a sectional view taken along the line -- in FIG. 2, FIG. 5 is an exploded perspective view of the step motor, and FIG. 6 is a pulse signal waveform diagram. In the figure, 2 and 3 are the first and second rotors, 7 and 8
are the first and second stators, 9 and 11 are A-phase stator convex poles, 10 and 12 are C-phase stator convex poles,
13 and 15 are B phase stator convex poles 14 and 16 are D
This is a phase stator convex pole.

Claims (1)

[Claims] 1 In a step motor having at least four phases of stator windings, two or more rotors having a large number of rotor teeth on the outer peripheral surface are arranged on one rotor shaft with a non-magnetic material interposed between each rotor. established,
The same number of stators as the rotors are provided, each having a plurality of pairs of stator convex poles extending radially inward from the outer periphery in the rotating direction, corresponding to each rotor, and a non-magnetic material is interposed between each stator. The stator windings of each phase are wound around each pair of stator convex poles so that at least two phases of stator windings are attached to each pair of stator convex poles. A step motor characterized in that a closed magnetic path passing through the outer periphery is formed magnetically independently.