DE102012212768A1 - Stator for construction of stator assembly for electronically commutated electrical motor, has ring segment provided with return element directed inwardly towards stator teeth, where return element includes specific range of segment angle - Google Patents

Abstract

The stator (5) has as a ring segment or cylindrical segment provided with a return element (11), where the return element is directed inwardly towards stator teeth (7). The return element includes a segment angle between 180 and 320 degrees, where the stator teeth include tooth heads spaced apart from each other in a circumferential direction. Identical sheet metal laminations are arranged to form the stator, where non-conductive isolation masks are provided at end faces of the stator. Independent claims are also included for the following: (1) a stator assembly for an electrical machine (2) a method for establishing a stator assembly for an electrical machine.

Description

Technical area

The present invention relates to electrical machines, in particular electronically commutated electrical machines. More particularly, the present invention relates to methods of constructing stator assemblies for small size electrical machines.

State of the art

Electric machines of small size were previously designed as brush-commutated electric machines with internal rotor, since they are inexpensive to manufacture. However, such electrical machines have the disadvantage that they have a relatively low torque density and a relatively high mass. Therefore, in many applications, small size, brush-commutated electrical machines are rapidly being replaced by electronically commutated electrical machines.

Already due to the elimination of brushes have electronically commutated electrical machines on a longer life and cause less noise. Furthermore, high frequency electrical interference attributable to brush commutation is eliminated in these electrical machines, so that no elaborate shielding measures are required.

In order to increase the torque density, electronically commutated electrical machines can also be formed with a higher number of poles, which is only possible to a limited extent in brush-commutated electrical machines due to mechanical manufacturing tolerances. An increased number of poles increases the torque density of the electric machine and therefore reduces their volume, their mass and the required material use, whereby the higher costs, which are mainly due to the required power electronics for driving stator coils of the electric machine, at least partially compensated.

In electronically commutated electrical machines with increased numbers of poles, stator assemblies having a relatively large number of teeth are required, carrying corresponding stator windings. In contrast to the wound rotor in brush-commutated electrical machines, the stator teeth are wound in electronically commutated electrical machines (internal rotor machines). However, since the stator teeth are oriented toward an inner recess in which a rotatable rotor is disposed, the distance between the stator teeth decreases toward the ends thereof.

Electronically commutated internal rotor machines of small size are usually wound by a winding tool passes through adjacent grooves, winding a winding wire around the lying between the grooves stator tooth. However, in order to guide the winding tool through the grooves, it is necessary that the groove openings have a sufficient width to allow the winding tool to be passed through the grooves without contacting the stator tooth. This requires relatively large slot openings of between 3 and 4 mm.

In electronically commutated electrical machines such large slot openings can lead to high cogging torques, which can result in problems with vibration, noise and increased eddy current losses. In conventional electronically commutated electric machines, the ratio of the sum of the groove openings to the total circumference of the inner recess of the stator assembly may be about 40%, with a ratio in a range of 20% or less being desirable. However, such ratios can not be achieved using the needle winding method.

Also, using the needle winding method, only groove fill factors between 30 and 35% can be achieved because the winding needle requires a region to pass through the grooves. However, groove fill factors in a range of 45% or more are desirable. A higher slot fill factor increases motor efficiency and can be achieved, in particular, by increasing the wire diameter of the windings.

To construct a stator assembly for an electrical machine, a chain of connected stator segments, each with one tooth, can be arranged in a straight line and wound in this arrangement, so that the grooves existing between the stator teeth have a sufficient width in order to be able to pass the winding needle. Subsequently, the rectilinear arrangement of the stator is placed in a circular shape, so that a stator assembly is formed with an inner recess, wherein the tooth tips of the individual stator teeth are moved against each other and the groove width decreases significantly.

Furthermore, the groove fill factor is significantly increased by the narrowing of the groove cross-section in the circular arrangement. However, the method has the disadvantage that in a circular arrangement of previously linearly interconnected stator segments whose tooth bases are bent against each other, so that a weakening of the material occurs at the tooth bases, which can increase the magnetic resistance there. Especially since the tooth bases form a magnetic return area, an increase in the magnetic resistance leads to a decrease in the torque capability of the electric machine.

Often, to avoid cracking in the area of the tooth bases, notches are provided in the areas where the tooth bases are bonded together to prevent cracking or other degradation of the magnetically conductive material. The provision of indentations, however, represents a reduction of the cross-section in the magnetic return region, whereby the magnetic resistance is systematically increased.

In particular, since stator assemblies for small size electrical machines are formed by stacking laminations, bending a straight line array of stator teeth to a cylindrical stator assembly for a small size electrical machine would result in significant stress on the stator base opposite sides of the stator bases the material used in particular for laminations would tear with high probability.

Furthermore, in the manufacturing process, it may be difficult to bend a rectilinear series of stator teeth, which are connected to one another at stator bases, so as to obtain an exactly circular-cylindrical stator arrangement which is required for the construction of a rotary electric machine.

It is therefore an object of the present invention to provide a stator for constructing a stator assembly for an internal rotor machine of small size available. A further object of the present invention is to provide a method for constructing an electrical machine, with which smaller slot openings and an increased slot fill factor can be achieved.

Disclosure of the invention

This object is achieved by the stator element for constructing a stator assembly for an electric machine with an internal rotor according to claim 1 and by the stator assembly, the electric machine and the method for constructing a stator assembly for an electrical machine according to the independent claims.

Further advantageous embodiments of the present invention are specified in the dependent claims.

In accordance with a first aspect, a stator element is provided for constructing a stator assembly for an electrical machine with an internal rotor, the stator element having a yoke element designed as a ring segment or cylinder segment and stator teeth pointing inward from the yoke element, wherein the segment of the yoke element has a segment angle between 180 ° and 320 °.

An idea of the above stator element is to provide it with a geometry that can be bent after winding the stator teeth into an annular stator assembly. Since a straight-line arrangement of stator teeth can not be bent into a circular stator arrangement with a lamellar structure after winding, the stator element according to the invention provides the stator element or laminations of laminations for constructing the stator arrangement with one of the stator elements Circle-shaped structure or a slightly open contour, d. H. segment-shaped to provide, wherein the outer circumferential extent of the stator corresponds to the outer periphery of the stator assembly to be produced. In other words, the stator element is provided in a form which would be obtained if a stator arrangement to be produced were cut open and bent uniformly.

Such a stator element has the advantage that the ends of the stator teeth have a higher groove width, through which a winding needle can easily apply the windings around the stator teeth. However, after winding the stator teeth, an unfilled area remains between the stator teeth, but decreases as well as the groove width when the wound stator element is bent into an annular stator assembly. In this case, the groove widths between the individual tooth heads likewise decrease, so that a substantially circular-cylindrical stator arrangement is formed.

Another advantage of the construction of a stator assembly of the stator according to the invention is that in a lamellar structure, the sheet material from which the laminations are constructed, with a lower flexibility and thus can be formed with a higher silicon content, since the mechanical deformation of the laminations to complete Close to the stator arrangement remains comparatively low. A laminar plate with a high silicon content is very advantageous because iron losses in the stator can be reduced and thereby the motor efficiency can be improved, which is advantageous in particular with a high number of motor poles.

Furthermore, the stator teeth may have tooth tips which are circumferentially spaced from each other.

The stator element may be formed with a plurality of similar laminations, which are arranged in coincidence to form the stator.

It can be provided that the stator element is provided at its end faces with one or more electrically non-conductive insulation masks, which are formed substantially similar to a cross section of the stator element transversely to an axial direction.

According to one embodiment, the one or more isolation masks may be provided with notches on its outer periphery.

• – das obige Statorelement; und
• – Statorspulen, die um die Statorzähne gewickelt sind;

wobei das Statorelement von dem Ringsegment oder Zylindersegment in eine Ringform bzw. Kreiszylinderform gebogen ist, so dass einander gegenüberliegende Enden des Rückschlusselements aneinander anliegen.In another aspect, a stator assembly for an electrical machine is provided, comprising:

• The above stator element; and
• - stator coils wound around the stator teeth;

wherein the stator element is bent from the ring segment or cylinder segment into an annular or circular cylindrical shape, so that opposite ends of the return element abut each other.

In another aspect, an electric machine is provided with the above stator assembly.

• – Bereitstellen des obigen Statorelements;
• – Bewickeln mindestens eines Statorzahns des Statorelements mit einem Wicklungsdraht, um eine den mindestens einen Statorzahn umgebende Statorspule zu erhalten; und
• – Biegen des bewickelten Statorelements zu einer Ringform bzw. einer Kreiszylinderform, so dass Segmentenden des Ringsegments bzw. des Kreiszylindersegments aneinander anliegen.

According to a further aspect, a method for constructing a stator assembly for an electrical machine is provided, comprising the following steps:

• Providing the above stator element;
• - winding at least one stator tooth of the stator element with a winding wire to obtain a stator coil surrounding the at least one stator tooth; and
• Bending the wound stator element into a ring shape or a circular cylindrical shape so that segment ends of the ring segment or the circular cylinder segment abut one another.

Brief description of the drawings

Preferred embodiments of the present invention will be explained in more detail with reference to the accompanying drawings. Show it:

1 a representation of a sheet metal section of a lamination for the construction of a stator for a stator assembly;

2 a schematic representation of a process for winding the individual stator teeth of the stator of the 1 ;

3 a representation of the connection of the individual stator coils in a neutral circuit;

4 a schematic representation of a stator assembly consisting of the wound stator elements of 3 is formed;

5 a schematic representation of an insulation mask for a front end of a stator made of a plurality of laminations stator, which is applied to a winding of the teeth of the stator on the front sides of the stack assembly;

6 the shape of the isolation mask after forming the stator assembly, as in 4 is shown; and

7 a representation of the arrangement of the laminations for the laminations for the construction of the stator with the best possible area utilization in a punching process.

Description of embodiments

In 1 is a sheet metal cut for a sheet metal lamella 1 to construct a stator assembly shown in a plan view. The sheet metal lamella 1 has the shape of a non-closed ring, wherein the recess in the illustrated embodiment has an angle of α = 105 °. In particular, the laminations 1 have a recess to a full circle in angular ranges between 40 ° and 180 °. That is, the corresponding segment angle of the lamination 1 is between 180 ° and 320 °.

The sheet metal lamella 1 has a conclusion area 2 and tooth areas 3 on top of that from the inference area 2 into the inside of the sheet metal lamella surrounded by the return area 1 protrude. The sheet metal lamella 1 has twelve tooth areas 3 on, which are provided for later construction of a stator assembly with twelve stator teeth. At the inward-facing ends of the tooth areas 3 are tooth-head areas 4 arranged, whose width is opposite to the width of the tooth area 3 is enlarged in the circumferential direction.

In the not completely closed, part-circular structure of the lamination 1 have the tooth head areas 4 a sufficient distance from each other to perform a winding by means of a Nadelwicklungsverfahrens after stacking the laminations. These are first similar laminations 1 stacked on top of each other to cover a stator element 5 train. Such a stator element 5 is in 2 shown and has a ring or cylindrical return element 11 and inwardly outgoing stator teeth 7 on. The stator element 5 is done using a needle winding device 6 wound by a winding needle alternately by adjacent grooves 8th is guided, wherein a winding wire between the adjacent grooves 8th located stator tooth 7 wrapped.

In this way, first all stator teeth 7 of the stator element 5 wound, with no complete filling of the cross section of the groove 8th can be done with winding wire, since the winding needle has a corresponding space requirement. After the last passage through the grooves 8th So remains a not filled with winding wire groove space.

During and after winding the stator teeth 7 be like in 3 shown, the individual wound stator coils 9 electrically connected to each other, in the present case in the form of a star connection with the neutral point S and the phase terminals A, B, C.

It follows, as in 4 illustrated, a deformation step in which the two ends of the partially circular shaped stator 5 be bent against each other until this at the position 10 meet each other, where they are connected to each other or pressed by other holding measures against each other, to a bending apart of the ends of the stator 5 to prevent.

By the deformation of the stator 5 to the pitch circle structure leads such a subsequent bending of the stator 5 in a ring shape or circular cylindrical shape to a uniform reduction of the groove width of the groove openings 11 and the groove cross-section 8th so that the groove width is reduced and the groove fill factor is increased. This leads to improved efficiency of an electric machine having such a stator assembly without the problems of the prior art occur, such as obtaining the circular cylindrical structure of a stator assembly formed from a stator and a deterioration of the magnetic properties of the flux material due to excessive bending of the stator element.

To ensure sufficient insulation of the winding wire on the stator teeth 7 to ensure, after stacking the laminations 1 to the stator element 5 at the front ends of an insulation mask 15 be applied as in a plan view example in 5 is shown. The isolation mask 15 has essentially the same sectional shape as the lamination 1 , but is made of an electrically non-conductive material, such as plastic.

To break the isolation mask 15 during the bending process to the circular cylindrical shape of the stator 5 To avoid, in the on the laminations 1 adjacent tooth base portions of the outer circumference outgoing notches 16 be provided, which represent predetermined bending points in the subsequent bending process to the stator assembly. For example, in 6 the isolation mask 15 represented as it is present after the bending process on the lamella stack. One recognizes the spreading of the notches 16 on the circumference of the insulation mask 15 ,

To the laminations 1 To save space and material from a sheet metal blank, they may be formed according to a tooth-like, interlocking structure on the punching die, wherein in each case one end of a sheet metal blade to be produced 1 in a defined by the pitch inner region of another similar sheet metal plate 1 is arranged. It creates a punching cut, as in 7 is shown, wherein in the punching cut area for punching a lamination 1 in each case two punched cut areas of two further laminations 1 protrude so that the yield of stamped laminations 1 from a given area of sheet metal is as large as possible.

Claims (10)

Stator element ( 5 ) for constructing a stator assembly for an electric machine with an internal rotor, wherein the stator element ( 5 ) designed as a ring segment or cylinder segment return element ( 11 ) and of the inference element ( 11 ) inwardly facing stator teeth ( 7 ), wherein the return element ( 11 ) has a segment angle between 180 ° and 320 °. Stator element ( 5 ) according to claim 1, wherein the stator teeth ( 7 ) Have tooth tips which are circumferentially spaced from each other. Stator element ( 5 ) according to claim 1 or 2 with a plurality of similar laminations ( 1 ) used to form the stator element ( 5 ) are arranged in coincidence with each other. Stator element ( 5 ) according to one of claims 1 to 3, wherein the stator element ( 5 ) at its ends with one or more electrically non-conductive isolation masks ( 15 ) which is substantially similar to a cross-section of the stator element (FIG. 5 ) are formed transversely to an axial direction. Stator element ( 5 ) according to claim 4, wherein the one or more isolation masks ( 15 ) with notches ( 16 ) are provided on its outer periphery. Stator arrangement for an electrical machine, comprising: - a stator element ( 5 ) according to any one of claims 1 to 5; and - stator coils ( 9 ) around the stator teeth ( 7 ) are wound; the stator element ( 5 ) is bent from the ring segment or cylinder segment into a ring shape or circular cylinder shape, so that opposite ends of the return element ( 11 ) abut each other. Electric machine with a stator arrangement according to claim 6. Method for constructing a stator assembly for an electrical machine, comprising the following steps: - providing a stator element ( 5 ) according to any one of claims 1 to 5; - winding at least one stator tooth ( 7 ) of the stator element ( 5 ) with a winding wire around one of the at least one stator tooth ( 7 ) surrounding stator coil ( 9 ) to obtain; and bending the wound stator element ( 5 ) to a ring shape or a circular cylindrical shape, so that the segment ends of the ring segment and the circular cylinder segment abut each other. A method according to claim 8, characterized in that the winding of the stator tooth ( 7 ) is performed by means of a needle winding machine, wherein a winding needle alternately by adjacent grooves ( 8th ) to be led. Method according to claim 8, characterized in that the laminations ( 1 ) for the stator element ( 5 ) are punched out of a sheet metal blank to save material, wherein the structure of the punching die is designed such that one end of a sheet metal blade to be produced ( 1 ) in a defined by the pitch inner region of another similar sheet metal plate ( 1 ) intervenes.

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