Metal working – Method of mechanical manufacture – Electrical device making
Patent
1998-06-17
2000-01-18
Young, Lee
Metal working
Method of mechanical manufacture
Electrical device making
29622, 337 62, 337 49, 337 36, H01H 6902
Patent
active
060148039
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for producing a thermal triggering system for an electric switchgear. The electric switchgear includes bimetal elements.
The invention relates to a thermal triggering system for an electric switchgear, the bimetal strips, with a slide having receptacles, in which the bimetal elements are received, a switching element for triggering a switching operation, and a differential lever which is fastened to the slide and which shortens its distance from the switching element as a result of the movement of said slide in the pushing direction, the differential lever being fastened to the slide via a first and a second bearing point.
BACKGROUND INFORMATION
Conventional thermal triggering systems are produced for power switches. Here, a deflection of three bimetal strips as a result of overload currents is utilized for a switching operation. The switch is not actuated directly, but via the slide which is adapted to the position of the bimetal strips. The differential lever is pressed against the switching element by the slide and thus triggers the switching operation. The components of the switchgear have unavoidable tolerances and, in terms of their arrangement and interaction, form a tolerance chain. The effect of this has to be compensated on the ready-assembled switch. It has therefore been customary until now to make the position of the switching element adjustable. Adjustment was carried out via a fine thread screw, using which it was possible to set forward or backward a pivotably mounted carrier for the switching lever. It was thereby possible for the distance between the switching element and the differential lever to be set at a predetermined value a.
A conventional thermal triggering system for an electric switchgear is described in U.S. Pat. No. 4,691,184. The conventional thermal triggering system includes calibrating or adjusting elements.
SUMMARY OF THE INVENTION
An object according to the present invention is to improve a method for producing a thermal triggering system by dispensing with adjusting elements used until now, thus reducing costs. The object of the present invention is achieved in that the slide is produced together with the first bearing point designed as a center of rotation, in that the position of the switching element in the electric switchgear is measured, and in that the second bearing point is calculated as a function of the measured position of the switching element and is executed on the slide which is thereupon mounted in the associated switchgear.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 shows a thermal triggering system without an adapted switching travel according to the present invention.
FIG. 2 shows the thermal triggering system with the adapted switching travel.
DETAILED DESCRIPTION OF THE INVENTION
Power switches are equipped with a thermal triggering system 1 for protection against overcurrents. The thermal triggering system according to FIG. 1 comprises three bimetal strips 2, which are each provided with a heating winding (not shown), a slide 3, a differential lever 4 and a switching element 5. Receiving slots 6, in which the bimetal strips 2 are inserted, are worked in the slide 3. The slide 3 can be displaced in the pushing direction, indicated by double arrow 7, as a result of the deflection of one or more bimetal strips 2 when overload currents occur. The differential lever 4 oriented essentially transversely to the pushing direction is fastened to the slide 3, said differential lever having a nose 8 at its end facing the switching element 5. This nose 8 is at a distance x from the switching element 5 in the pushing direction, said distance being dependent on the temperature of the bimetal strips 2, i.e., the heating caused by the load current. In the currentless state, this distance x is to have a definite value a. The differential lever 4 is fastened to the slide 3 via two bearing points 9, 10. The first bearing point 9 is a point which is fixed relative to the slide 3 and which, in the cu
REFERENCES:
patent: 4691184 (1987-09-01), Wulff
patent: 4806897 (1989-02-01), Fahner et al.
Siemens AG
Smith Sean
Young Lee
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