Electricity: electrothermally or thermally actuated switches – Electrothermally actuated switches – With bimetallic elements
Patent
1986-05-27
1987-09-01
Broome, Harold
Electricity: electrothermally or thermally actuated switches
Electrothermally actuated switches
With bimetallic elements
337 62, 337 82, H01H 6100, H01H 7116
Patent
active
046911847
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a bimetal releaser for excess currents as defined in the preamble of claim 1. Such a releaser is disclosed, for example, in DE-OS No. 3,149,811. In the known configuration, separate calibrating elements are provided on both sides of each bimetal strip, each disposed in unilaterally open chambers of the release bridge on the one hand and the differential bridge on the other hand. These calibrating elements are arranged opposite one another and are in contact with the bimetal strip. After adjustment, the bimetal strips are encased in a hardening plastic mass. These calibrating elements have such a configuration and are held in the chambers in such a manner that, during the calibrating or adjustment process, they lie in a form and force locking manner and under the influence of force simultaneously at both sides of each bimetal strip. The initially loosely arranged calibrating elements are to be fixed in such a manner that, if all available bimetal strips are heated uniformly, the subsequently connected switch lock of a switch is actuated only if the release bridge and the differential bridge have exceeded the set calibration position due to the joint action of all bimetal strips. If one current phase is missing, for example, the release bridge is to be held back and only the differential bridge is to be deflected to such an extent that the switch lock is released.
It is the object of the invention to provide a reliably adjusted bimetal releaser of the above-mentioned type and to reduce the costs involved in the adjustment. The object of reducing the calibration expenditures for calibrating such a bimetal releaser is realized by providing the release end of each bimetal strip with an aperture for accommodating a calibrating element which, after being inserted into this aperture, is supported at the release bridge as well as the differential bridge and is freely movable in the opening if the bridge moves during the adjusting process until it is fixed after completion of the adjustment.
FIGS. 1 to 9 are schematic illustrations of an embodiment of the subject matter of the invention.
FIG. 1 is a side view and
FIG. 2 is a top view of an adjusted bimetal releaser. FIGS. 3 and 4 are two side views of the releaser according to FIG. 1 during the adjusting process.
FIGS. 5a to 5c show various embodiments of a bimetal at its release end.
FIGS. 6 and 7 are schematic illustrations, a top view and a side view, of a device for deflecting the bimetal releaser according to FIGS. 1 to 4 during the calibration process.
FIG. 7a shows a detail of FIG. 7.
FIGS. 8 and 9 show a second embodiment.
The bimetal releaser according to FIGS. 1 to 4 includes a release bridge 10 which is mounted at 11 in the housing or frame of a switch which is not illustrated. A differential bridge 12 is mounted at release bridge 10 so as to be rotatable about 13. The transfer lever 14 of a switch mechanism is disposed at differential bridge 12. This lever leads to a lock for a motor protection switch or a contact for a bimetal relay. The numeral 15 indicates the point of release of the switching mechanism which, in a motor protection switch, corresponds to release of a lock and, in a bimetal relay, to the point at which the contact snaps over. In FIG. 1, this point is spaced a distance 16 from the end of transfer lever 14. Three bimetal strips 17 charged by the current of the three-phase excess current switch (not shown) are disposed between the two bridges 10 and 12. At release end 18, bimetal strips 17 are provided with calibration elements 19 in the form of discs which are fixed to the ends 18 of bimetal strips 17 by weld dots 20. Discs 19 are seated in apertures 21 which, according to FIG. 5a, in this case are unilaterally open slits. The view of FIG. 2 shows the different positions of the three bimetal strips 17 with respect to bridges 10 and 12 caused by manufacturing tolerances.
FIGS. 3 and 4 show two phases of the calibration process for establishing the calibrated state according to FIGS. 1 and 2. A device according to
Broome Harold
Licentia Patent-Verwaltungs-GmbH
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