JPS6350950B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a closed ring frame and a star-shaped magnetic pole inserted into this frame and fitted with a winding, the star-shaped magnetic pole having a hollow cylinder and a surrounding area around the cylinder. The present invention relates to a stator for a polyphase motor comprising magnetic pole pieces made of a single material in the axial direction and arranged radially in the direction of the axis.

In a known electric motor stator of this type (West German Patent Application No. 1814977), one end of the magnetic pole piece of the star-shaped magnetic pole is fitted radially into a hollow cylinder made of synthetic resin to a certain depth. .
Therefore, a ring-shaped synthetic resin intermediate layer is present between the radially inner surface of the pole piece and the original air gap, in order to specifically reduce the air gap between the pole piece and the rotor. The hollow cylinder must be cut from the inside. The hollow cylinder and the magnetic pole pieces are joined together when the hollow cylinder is manufactured by molding.
The pole pieces are made of a single piece of material and are ladder-shaped with sloped sides. The pole pieces are additionally provided with a synthetic resin layer on their sides. The star-shaped magnetic pole manufactured in this manner is inserted into the ring frame, and is fixed within the ring frame and itself by molding with molding resin.

Furthermore, in the stator of an electric motor known from US Pat. No. 2,607,816, the star poles are constructed by stacking a number of star pole pieces axially one on top of the other and holding them together, for example by screws. There is. Each individual pole piece is stamped out of a steel plate as a single piece, with radially extending pole teeth formed on the inner side. The pole pieces then connect the pole teeth radially inwardly, forming a magnetic bridge therebetween. A star-shaped pole consisting of a stack of individual pole pieces and fixed by an axially extending screw is inserted into a closed ring frame, or a ring frame component segment is inserted between the radially outer ends and a fixed Therefore, it is welded to the radially outer end of the magnetic pole tooth.

An object of the present invention is to provide a stator for a polyphase motor of the type mentioned at the beginning, which has a small leakage electric field and low magnetic resistance, and which also has a star-shaped magnetic pole and its coupling with the ring frame surrounding it. The goal is to make it stronger. This purpose, according to the invention, comprises a closed ring frame and a star-shaped pole inserted into this frame and fitted with a winding, which star-shaped pole has a hollow cylinder and a surrounding area of this cylinder. A stator for a multi-phase motor consisting of magnetic pole pieces made of a single material arranged radially in the axial direction, the inner ends of the magnetic pole pieces in the radial direction extending beyond the hollow cylinder to connect the rotor and stator. is inserted into the hollow cylinder until it reaches the air gap between, and its radially outer end is welded to the inside of said ring frame surrounding this outer end by electron beam welding performed on the outside of this ring frame. This is achieved by The hollow cylinder may be a molded product, and the pole pieces may be molded together at the same time as the hollow cylinder is manufactured. If it is desired to dispense with special equipment or molds for this type of mold, the hollow cylinder can be prefabricated as a part with an axial slot into which the pole piece is later inserted. Whether the pole piece and the hollow cylinder are molded together or the pole piece is later inserted into the hollow cylinder, there is no magnetic flux between the radially inner ends of the individual pole pieces of the star pole. To prevent bridges from forming,
The hollow cylinder is preferably made of a non-ferromagnetic material, particularly preferably aluminum or synthetic resin.

If the stator of a polyphase motor, especially a step motor, is manufactured according to the present invention, sufficient strength of the entire stator can be obtained even though the magnetic pole pieces are inserted into the hollow cylinder up to the air gap. Even when severe stress occurs or when a synthetic resin hollow cylinder contracts, mechanical strength is maintained between the star-shaped magnetic pole and the part of the surrounding yoke ring frame through which the magnetic flux flows. This makes it possible to form a transition portion with low electrical resistance.

Note that the coupling strength of the magnetic poles can be further increased by providing an axial protrusion on the radially inner side of both sides of the magnetic pole piece and molding the protrusion to a hollow cylinder extending in the axial direction.
In order to further strengthen the mutual fixation of the hollow cylinder and the magnetic pole pieces that are molded together, the holes are provided with jagged grooves in the portions of the magnetic pole pieces that come into contact with the hollow cylinder, and the molding material of the hollow cylinders is embedded in this portion. It's good to do that.

Insulation on both end faces of the pole piece can be provided by a synthetic resin layer, which can also be applied, if necessary, to cover the periphery of both sides and, if necessary, simultaneously with the hollow cylinder as an integral part. molded. If special insulation is required between the pole piece and the winding to which it is attached, the entire surface of the pole piece facing the winding is preferably provided with a synthetic resin layer, which covers the pole piece. It can be molded at the same time as mold joining to the hollow cylinder. A stator that avoids additional insulation between the wound star pole and the surrounding ring frame or that is attached when the wound star pole is inserted into the surrounding ring frame. In order to avoid damaging the winding, a synthetic resin cap with a comb-shaped axial extension is fitted to the coil end of the winding attached to the star-shaped magnetic pole, and the axial extension of this cap is used to connect the winding. The winding is inserted into the space so as to cover the ring frame. If the stator winding is attached to the star pole by the needle method, it makes sense to insulate the star pole from the stator winding. On the other hand, when installing the stator winding by the so-called insert method, in which a coil is manufactured in advance, insulated, and inserted into the star-shaped magnetic pole, the insulation of the slot space or the side part of the star-shaped magnetic pole is There is no need to additionally provide this.

Furthermore, in the present invention, the position of the inner surface of the hollow cylinder is slightly set back from the position of the inner end of the magnetic pole piece, so that the inner end of the magnetic pole piece slightly protrudes inward from the inner surface of the hollow cylinder. Because of this structure, it is possible to secure a narrow air gap without any further processing after installing the magnetic pole piece in the hollow cylinder, especially when molding the magnetic pole piece inside the hollow cylinder. In this case, even if burrs occur on the inner surface of the hollow cylinder, the necessary space for the void and the inner hole for accommodating the rotor can be secured without removing the burrs through separate processing.

Next, the present invention will be explained in detail with reference to the drawings.

The stator of a polyphase motor, in particular a step motor in this example, consists of a ring frame 2 and a star-shaped magnetic pole inserted into the ring frame 2 and constituted by individual pole pieces 3 and a hollow cylinder 1, the magnetic poles of this star-shaped magnetic pole being A stator winding 4 is attached to the piece (FIG. 1). Note that the stator winding 4 is shown only in FIG. 1 for clarity. For the same reason, FIG. 1 does not mention the bearing bracket mounting, retaining and securing devices.

The ring frame 1 has a portion S formed by electron beam welding on its outer periphery at approximately the center in the axial direction.
It is welded to the magnetic pole piece 3. These welding joints are indicated by symbols S1, S2, and S3 in FIG. Therefore, even if the synthetic resin hollow cylinder 1 were to contract, the magnetic pole piece 3 and the ring frame 2, which serves as a yoke, are mechanically firmly held and the connection between them will not be broken.

As shown in FIG. 2, the side of the pole piece 3 facing the winding is provided with an insulating layer 33 which, like the lateral insulating layer, can be applied to the hollow cylinder 1 if required. It can be molded during manufacture, or it can be incorporated as a component, such as a separate insulating plate. Note that a cover plate 34 may be provided to protect the stator winding.

FIG. 3 shows the outer shape of a pole piece in which the winding portion is rectangular. This magnetic pole piece is made using the so-called insert method, in which a pre-wound coil is fitted into a star-shaped magnetic pole.

FIG. 4 shows the outer shape of the pole piece, which additionally has an axially extending projection 35 at its radially outer end.
This is applied to the so-called needle method, in which the winding wire is wound using a needle.

Another different embodiment of the pole piece profile according to FIG. 4 is shown in FIG. 5, in which the side end faces of the pole piece have a step of widening towards the ring frame. As shown in these figures, the magnetic pole piece 3 has axial protrusions 31 and 32 inside the radial direction on both sides, which are fixed to the hollow cylinder 1 for reliable retention. It is. The holes 36 also serve to ensure a strong connection between the hollow cylinder and the pole piece.

6 and 7 show a synthetic resin cap 5, which is pushed over the coil end of the winding 4 attached to the star-shaped magnetic pole, and fixed with a spigot to the cylindrical portion of the star-shaped magnetic pole. The axial comb-like extension 51 then projects into the slot space of the winding to cover the slot space at least for the ring frame. The coil ends disposed in the pot-shaped space 52 are all covered in all directions, and the winding portion accommodated in the slot is protected against the slot opening, so that the insulating cap 5 protects the coil end. The winding is protected from mechanical damage during insertion of the wound star pole into the ring frame.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the stator of the present invention;
Figure 2 is a partial view of a cross section passing through the weld S of the same stator as above, Figures 3, 4 and 5 are external views of different embodiments of the magnetic pole pieces, and Figure 6 is a diagram of the coil end insulating cap. An axial sectional view, and FIG. 7 is a radial sectional view of the same as above. 1: Hollow cylinder, 2: Ring frame, 3:
Magnetic pole piece, 4: Stator winding, S: Welded part.

Claims (1)

[Claims] 1 comprising a closed ring frame and a star-shaped magnetic pole inserted into the frame and fitted with a winding, the star-shaped magnetic pole having a hollow cylinder and axially arranged radially around the cylinder; A stator for a polyphase motor consisting of magnetic pole pieces made of a single material, the magnetic pole pieces being inserted into the hollow cylinder until their radially inner ends cross the hollow cylinder and reach the air gap between the rotor and the stator. A polyphase electric motor is inserted into the ring frame and its radially outer end is welded to the inside of the ring frame surrounding the outer end by electron beam welding applied to the outside of the ring frame. Stator of.