Electricity: circuit makers and breakers – Electric switch details – Contact
Reexamination Certificate
1999-12-10
2001-02-13
Gellner, Michael L. (Department: 2832)
Electricity: circuit makers and breakers
Electric switch details
Contact
C335S016000, C218S022000
Reexamination Certificate
active
06188031
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a movable contact arrangement for a low-voltage circuit breaker having contact levers and a contact lever bracket holding the contact levers as well as a stationary conductor segment connected to the contact levers by flexible conductors, with the contact lever bracket movable around a pivot bearing, located in the region of the stationary conductor segment, which includes a journal molded onto the contact lever bracket and a stationary bearing opening positioned in a housing section of the low-voltage circuit breaker.
BACKGROUND INFORMATION
A contact arrangement of this type is described in German Patent No. 44 16 105.
FIG. 5
of the specification shows a supplementary view of a contact lever bracket
2
, equipped with a contact lever
1
, of a circuit breaker described in German Patent No. 44 16 105. According to this description, both lateral bearers
3
of contact lever bracket
2
are provided with a journal
4
, projecting to the outside, which engages bearing opening
5
of a housing section
6
(truncated in the illustration) of the circuit breaker. With a multipole circuit breaker design, this arrangement takes up a certain amount of space along a width. Partitions
7
(truncated in the illustration) between adjacent poles must therefore have a width corresponding to an axial depth of both bearing openings, plus a sufficient amount of clearance. The described pivot bearing design therefore affects the width of the circuit breaker.
Other conventional arrangements exist for the pivotable bearing assembly of the movable contact arrangement of a low-voltage circuit breaker. For example, German Patent No. 38 02 183 describes an arrangement in which the contact lever bracket is pivotably attached to the stationary conductor segment by a bearing pin. In this arrangement, lateral bearers of the contact lever bracket project over the stationary conductor segment, which, just like the conventional arrangement described in German Patent No. 44 16 105, also increases the width of the movable contact arrangement beyond the size required for electrical rating. Pivot bearings for movable contact arrangements that require no or only a very slight lateral projection over the stationary conductor segment are also known. One pivot bearing of this type, which is designed as an articulated current transfer arrangement, is described, for example, in U.S. Pat. No. 4,490,593. In contrast to a contact arrangement according to the present invention, each individual contact lever in this arrangement is provided with a bearing pin. Together with helical springs as the sliding element, this bearing pin also forms a means for transferring current. The production of the bearing opening requires a relatively expensive method for machining the stationary conductor segment. Due to their fluctuating electrical contact resistance, articulated current-transfer arrangements are also not suitable for all low-voltage circuit breaker applications.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a sturdy pivot bearing for the contact lever bracket, which does not require the width of the contact arrangement to be increased beyond the size needed for electrical rating purposes.
According to the present invention, this object is achieved in that the contact lever bracket has only one more or less centrally positioned journal with a length not exceeding the width of the movable contact arrangement, and at least one bearing opening is also located within the width of the movable contact arrangement, with the bearing being formed by interacting recesses and surfaces of two separable units of the low-voltage circuit breaker.
According to the present invention, no lateral projection of the pivot bearing over the stationary conductor segment needs to be taken into account, with the result that partitions between adjacent poles need to be only as thick as necessary for electrical insulation purposes. This advantageously reduces the circuit breaker dimensions. However, this advantage is not achieved at the expense of the mechanical reliability of the pivot bearing. Instead, a much larger supporting width is available for the journal, which has a positive effect on the service life and reliability of the circuit breaker.
The bearing opening is formed by interacting recesses and surfaces of two separable units of the low voltage circuit breaker. The complete bearing openings are produced in this manner only after the house section is assembled, which makes mounting the contact lever bracket much easier. One unit may be formed by the housing section of the circuit breaker, and the other unit by the stationary conduction segment which at least partially covers the recess.
A pivoting angle of the contact lever bracket when opening and closing the circuit breaker is relatively small. It is therefore possible to design an entire end area of the contact lever bracket as a journal. According to the present invention, however, a main arm of the contact lever bracket holding the journal may be designed so that it tapers in the direction of the pivot bearing, thus dividing the journal into two lateral journal areas, with each journal area assigned a bearing opening. This arrangement achieves the largest possible supporting width, thus providing a low-tolerance bearing assembly at a relatively low cost.
Unlike the usual pairing of a cylindrical journal with a cylindrical bearing opening, it may be more useful for the purposes of the present invention to give the one or more bearing openings a polygonal cross section. Possible shapes include, for example, rectangular, hexagonal, and octagonal cross sections. With the common methods used for producing plastic housings, these shapes may be easier to produce than cylindrical bearing openings, while they also make it possible to store a supply of lubricant that is sufficient for the entire planned service life of the circuit breaker.
The one or more bearing openings can be formed in the conventional manner by the interacting recesses and surfaces of two separable units of the low-voltage circuit breaker. The complete bearing openings are produced in this manner only after the housing section is assembled, which makes mounting the contact lever bracket much easier. One unit may be formed by the above-mentioned housing section of the circuit breaker, and the other unit by the stationary conductor segment which at least partially covers the recess.
REFERENCES:
patent: Re. 35507 (1997-05-01), Uchida et al.
patent: 3523261 (1970-08-01), Bianchi et al.
patent: 4490593 (1984-12-01), Cook
patent: 5313180 (1994-05-01), Vial et al.
patent: 6100490 (2000-08-01), Turkmen
patent: 38 02 183 (1989-08-01), None
patent: 295 03 327 U (1995-04-01), None
patent: 44 16 105 (1995-05-01), None
patent: 0 358 286 (1990-03-01), None
Gellner Michael L.
Kenyon & Kenyon
Nguyen Nhung
Siemens Aktiengesellschaft
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