Electricity: circuit makers and breakers – Switch activation inhibitor
Reexamination Certificate
2000-05-05
2001-06-26
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Switch activation inhibitor
C200S050210, C200S050260, C200S400000, C200S308000, C200S318000
Reexamination Certificate
active
06252186
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a switching device having an operating shaft for moving a switching contact arrangement into its ON and OFF switch positions. The switching device further includes an indicator element for the switch positions and a linearly displaceably guided blocking bar which is provided as protection against wrong operation and has working faces for cooperating with the indicator element. The switching device also includes a closing device for locking the switching device in the OFF position, having an OFF operator and a protective device for securing access to a traversing mechanism of the switching device.
BACKGROUND INFORMATION
A switching device of the type described above is described in German Patent No. 44 20 580. Access of a tool to the traversing mechanism here can be blocked by a protective device which can be operated as a function of the position of the blocking bar, where one of the working faces of the blocking bar can be covered by an opposing face of the indicator element which depends on the position of the operating shaft. This arrangement requires two-handed operation on the part of the user. First, the OFF key must be depressed before the protective device assigned to the traversing mechanism is opened or the closing device can be operated.
SUMMARY
An the object of the present invention is to implement the safety device which establishes the relationship between the OFF operator and the devices for insertion and retraction and for closing the switching device by means of a simple forced-action device. This device should have a forced action and should be operated without any auxiliary power. It should be easy to install in a space-saving manner with easy operation.
This object is achieved according to the present invention by the fact that the blocking bar has a cam element, and the OFF operator which is designed as a key has a carrier which cooperates with the cam element in such a way that the OFF operator can be moved into its effective position by a displacement of the blocking bar.
This achieves the result that any displacement of the blocking bar corresponding to the OFF switch position of the switching device at the same time necessarily moves the OFF operator into its active position, i.e., the OFF position. This not only frees the user from having to operate the OFF operator separately, as was necessary in the past, but also permanently displays the special operating state of the switching device. Any other person working with the switching device will thus immediately recognize the operating state of the switching device on the basis of the position of the OFF operator and need not operate the OFF operator on a trial basis as was necessary in the past.
For the purpose of the present invention, OFF operators having a key that has eccentrically arranged swivel pins and is designed like a rocker are particularly suitable. This design thus facilitates twist-free insertion by using the cam element. However, the present invention can also be used in combination with traditional parallel guided pushbuttons if twist-free guidance is ensured. In both cases, it may be desirable for the cam element to be designed like a fork for symmetrical entrainment of the OFF operator in order to avoid increased friction due to twisting or jamming of the key of the OFF button.
The basic system of an ON and OFF limit switch is described in detail in German Patent No. 43 33 828 and German Patent No. 44 20 580, and therefore need not be explained again further here.
With proper functioning of the switching device, a reliable correlation between the position of the OFF operator and the switching contact arrangement can be assumed. In the case of a serious disturbance, e.g., contact welding, however, the switching contact arrangement can be closed when the OFF operator is depressed. However, because of the rigid mechanical coupling of the switching contact arrangement having the operating shaft, the indicator element also remains in the ON position and thus blocks any displacement of the blocking bar. Again in this case, access to the traversing mechanism is impossible with the device according to the present invention and the closing operation cannot be activated either. Thus, the isolator condition, as it is called, is ensured. Access to the traversing mechanism may be designed as a “portal” in a conventional way (see, e.g., German Patent No. 44 20 581). Then the OFF key returns to the normal position automatically or only after the “portal” has been closed depending on whether or not the “portal” has a bias tension in the closed position.
REFERENCES:
patent: 5337210 (1994-08-01), Ishikawa et al.
patent: 5945648 (1999-08-01), M'Sadoques
patent: 6080947 (2000-06-01), Ulerich et al.
patent: 6144002 (2000-11-01), Coudert et al.
patent: 43 33 828 (1995-03-01), None
patent: 44 20 580 (1995-11-01), None
patent: 44 20 581 (1995-11-01), None
patent: 42 11 421 (1997-02-01), None
patent: 0 226 532 (1987-06-01), None
Ahlert Torsten
Dahl Jörg-Uwe
Godesa Ludvik
Liebetruth Marc
Friedhofer Michael
Kenyon & Kenyon
Siemens Aktiengesellschaft
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