Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-07-10
2002-04-02
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S256000, C310S256000
Reexamination Certificate
active
06365999
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a stator structural unit for an electrical machine, particularly an alternating-current machine [a. c. generator] in the form of a transverse-flux machine.
2. Description of the Prior Art
Electrical machines in the form of a. c. generators, particularly transverse-flux machines, are known in various embodiments from a multiple number of publications. In this connection, refer to the publications:
1. DE 3,536,538 A1
2. DE 3,705,089 C1
3. DE 3,904,516 C1
4. DE 4,125,779 C1
These essentially describe the basic principle and the construction of a. c. generators operating according to the transverse-flux principle. The machines comprise at least one stator structural unit with one stator, particularly comprising a multiple number of strip-wound cut cores, with at least one armature winding and a rotor with magnetic excitation arranged lying opposite the winding. The known stator structural units thus have a stator housing with cross-pieces and with so-called digits for fixation and heat discharge at the strip-wound cut cores of the outer and inner stators, as well as a support for the centering of the armature winding. The outer strip-wound cut cores, i.e., those strip-wound cut cores of the outer stator, are fixed in the radial direction between the cross-pieces by means of adjusting screws and retaining clips, or, in other known designs, are fixed roughly radially by means of a retaining ring of nonconducting material. The strip-wound cut cores of the inner stator are roughly radially fixed between the digits of the stator housing in the peripheral direction and through the coil. For final fixation, the stator which has been premounted with a suitable casting compound and with the use of a so-called core ring, is cast. The casting of the stator unit is a very time-consuming process, due to the very complicated housing structure. So-called winding and impregnating devices are necessary for production of exciting coils. Due to the multiple number of individual parts and their complex configuration, assembly is very time-consuming, particularly of the strip-wound cut cores at the outer stator with fastening clips. By analogy, this holds true also for the strip-wound cut cores contained in the inner stator. Another essential disadvantage in the production of the stator structural unit comprises the fact that the exciting coil and the strip-wound cut cores must be cast in the stator housing, and a post-processing of the casting compound is usually always necessary. The casting compound in turn limits the admissible maximum temperature of the entire structural unit to a specific value during operation. This in turn acts negatively on the obtainable permissible continuous output. Production itself requires expensive configured tools as well as highly qualified employees for assembling.
Therefore the object of the invention is to further develop a stator structural unit of the type named initially for an a. c. generator, particularly a transverse-flux machine, such that the named disadvantages are avoided. Taken individually, the stator structural unit will have a simple structural design, which assures a cost-favorable production and easy assembly. An adverse effect on the properties with respect to heat discharge is to be avoided.
BRIEF SUMMARY OF THE INVENTION
It is provided according to the invention to design stator structural units for electrical machines, particularly transverse-flux machines, with at least one stator unit bearing an armature winding, which forms an air gap with a rotor in the installed position, considered in the radial direction in axial section, of at least one electrical ground element configured preferably in annular form extending annularly in the peripheral direction considered in the installed position and tooth elements which can form a structural unit with the ground element. The annular electrical ground element is produced by powder metallurgy or manufactured from a component that has been produced by powder metallurgy. The tooth elements are comprised of a soft magnetic material or substance. The tooth elements can thus be coupled with the annular ground element such that the tooth elements, considered in an axial section of the electrical machine, and together with the annular ground element, describe an essentially U-shaped cross-sectional surface, whereby the two legs of the U-shaped section are each formed of tooth elements. Tooth elements in the installed position are to be understood as projections extending to the rotor, which form edges or edge surfaces in the peripheral direction, whereby the two edges pointing together in the peripheral direction describe two stator tooth gaps in the peripheral direction of adjacent tooth elements.
A plurality of tooth elements, which lie on a common diameter with respect to the axis of symmetry of the electrical machine, in the axial direction and considered in axial section, or which can be described by projecting onto the axis of symmetry through a common point on the latter, form a so-called soft-iron unit. In order to produce a U-shaped cross section, the ground element is coupled with two soft-iron units.
Preferably star-shaped soft-iron elements are designed in the peripheral direction such that they have a multiple number of individual projections extending away from the annular ground element in the direction of the rotor and describing the tooth elements. The soft-iron units describing the tooth elements in the peripheral direction are arranged at specific distances from one another, depending on the configuration of the rotor. Preferably, the projections forming the tooth elements are combined with the annular ground element, particularly joined in a radial manner, by means of a common base unit extending in the peripheral direction, with which the latter preferably form a structural unit.
The tooth elements or the soft-iron units formed from these elements, particularly two tooth elements each time, form the U legs of the stator unit extending away from the annular ground element each time, viewed in an axial section. The tooth elements of a soft-iron unit can thus be coupled each time individually in a frictional connection and/or form-fitting manner with the electrical ground element. Preferably, however, the soft-iron units are designed each time as annular elements or the individual tooth elements are carried by a common base unit. In order to avoid circular currents, the annular elements are designed so that they are interrupted in the peripheral direction, at least at one place. The subdividing into a multiple number of segments, whereby each segment contains a multiple number of tooth elements, is also conceivable. The coupling or combining of the soft-iron units with the annular electrical ground element can be designed in different ways. Connections are thus conceivable by means of:
a) frictional connection
b) form-fitting connection
c) frictional and form-fitting connection.
In designs with frictional connection, preferably the soft-iron units are assembled with the annular ground element by means of a press connection. This offers the advantage that there is no dependence of service life on the composite materials used, since there is no pure material connection. The concrete configuration of the press connection can be produced in different ways. Selection can be made according to the opinion of the competent person skilled in the art.
The basic possibility for the configuration of elements of electrical machines from or as powder-metallurgically produced parts is already known from the publication “Composites pave the way to the electrical machine designs of the future” (Höganäs Iron Powder Information PM 95-4). These involve, however, the complete design of elements from such materials. The inventors have recognized the fact that the gross transfer of this possibility to transverse-flux machines does not offer the desired advantages and thus searched for more suitable designs producing improved r
Angerer Wolfram
Koll Stefan
Lange Andreas
Mühlberger Uwe
Nguyen Tran
Ohlandt Greeley Ruggiero & Perle LLP
Voith Turbo GmbH & Co. KG
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