Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-02-04
2001-05-08
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S180000, C310S190000
Reexamination Certificate
active
06229244
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a synchronous machine, in particular a generator for a motor vehicle, provided with an excitation system composed of a plurality of electrically excited individual poles in a stator or a rotor, preferably in form of claw poles excited by at least one joint excitation coil, and with a stray flux compensation device arranged in free spaces between the claw poles.
A synchronous machine of this type is disclosed for example in the German patent documents DE-PS 1209651 and DE 8905353 U1. Permanent magnets are utilized as the stray flux compensation device, which are arranged in the stray flux region between the claw poles. The mounting of the permanent magnets between the claw poles requires especially constructed claw poles or additional holding parts. Therefore, not only the construction of the synchronous machine becomes expensive, but also the compensation of the stray flux is dependent on temperature, aging and tolerances of the construction of the claw poles.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a synchronous machine of the above mentioned type, which eliminates the disadvantages of the prior art.
More particularly, it is an object of the present invention to provide a synchronous machine of this type, in which a compensation of the stray flux is provided so that a simplification is obtained in the construction of the synchronous machine, and also the influence of temperature, aging and tolerances is reduced to an insignificant value.
In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a synchronous machine in which the stray flux compensation device is formed as an additional winding through which current flows and which surrounds the claw poles so that the current direction changes from one free space to another free space and a current to the neighboring claw poles produces an additional flux which supports the main flux and counteracts the stray flux.
The additional winding is easily arranged and requires no expensive mounting. The additional winding contributes in this way for support of the main flux or for reduction of the stray flux, and at the same time it does not change the properties of the compensation, such as for example the coercitive force with the permanent magnets.
The aging of the additional winding is insignificant and the additional winding is not susceptible to the counter field, so that a booster excitation is possible. The tolerances of the claw poles can not exert any action on the efficiency of the stray field compensation. Moreover the magnetization can be dispensed with.
In accordance with a preferable embodiment of the present invention, the additional winding is guided meanderingly around the claw poles. The electrical properties of the additional winding can be provided in a simple manner so that the additional winding is connected in series with the excitation winding.
The design can be also selected so that the additional winding is composed of thin wires with many windings, which are connected parallel to the excitation winding.
The additional winding can be surrounded by synthetic plastic, glass fiber or anti-magnetic material, and joined by adhesion or impregnation to form a compact unit. This facilitates the mounting of the additional winding in the stray field regions also when the rotor and stator is prefabricated.
In order to sufficiently fix the additional winding on a rotor with high rotary speeds, to compensate the centrifugal forces, in accordance with a further embodiment of the present invention the claw poles are formed as parts of plates, and the winding parts of the additional winding which face the plates are connected with the plates by anti-magnetic mounting means. The mounting means can be formed in a shell-like manner.
In order to provide a sufficient strength, additionally the free ends of the claw poles can be fixedly connected with the facing opposite-pole plates by the anti magnetic connectors.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
REFERENCES:
patent: 4900968 (1990-02-01), Feigel et al.
patent: 5444321 (1995-08-01), Honda et al.
patent: 5483116 (1996-01-01), Kusase et al.
patent: 5783888 (1998-07-01), Yamano
patent: 89 05 353 (1990-04-01), None
Nguyen Tran
Robert & Bosch GmbH
Striker Michael J.
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