Electricity: electrothermally or thermally actuated switches – Electrothermally actuated switches – With longitudinally expansible solid element
Patent
1989-05-02
1990-11-27
Broome, H.
Electricity: electrothermally or thermally actuated switches
Electrothermally actuated switches
With longitudinally expansible solid element
337140, H01H 6106, H01H 7118
Patent
active
049739310
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a tripping device for circuit breakers according to the precharacterizing clause of Claim 1. Such a tripping device is known, for example, from CH-A-616270. In this document, a thermoelectric switch comprising a tripping element of a memory alloy with two-way effect is known. The switch possesses at least one clamping device which acts in conjunction with the tripping element and the force of which, which acts on the tripping element, is used for defining the temperature of the switching process. In this arrangement, the tripping element has the dual function of slow- and of fast-acting tripping elements. In a special embodiment, the tripping element is a wire of memory alloy. The actual contact of the switch is operated via a complicated switching mechanism comprising several tension and compression springs.
The invention is then based on the object of creating a tripping device for circuit breakers of the type mentioned above, in which arrangement the switching mechanism is particularly simple and the tripping element can be both a wire of a memory alloy and a wire of a thermally expanding metal. It should also be unimportant whether a memory alloy according to the one-way or two-way effect is used.
In a tripping device of the abovementioned type, this object is achieved by the features of Claim 1. The tripping device according to the invention has the great advantage that the tripping mechanism is designed to be particularly simple and enables both tripping with contraction and with expansion of the wire-shaped tripping element. In a particular embodiment according to Claim 2, a compression spring is arranged between the tripping lever and a housing rib. As a result, the wire-shaped tripping element is always stretched. If a thermally expanding wire is used according to Claim 3, a precisely determined thermally dependent length is given due to the reversible and reproducible thermal effect of the wire. The temperature-dependent length is also always known if a memory alloy--particularly with two-way effect--according to Claim 4 is used. If, in the above cases, the wire breaks due to careless handling, the circuit breaker is also tripped. If wires of memory alloy according to the one-way effect are used as tripping element and if it is required that the circuit breaker should switch on again after a fault, a stop is required in the housing. Nevertheless, in order to ensure tripping in the case of a wire break, the intermediate lever with additional compression spring according to Claim 5 or the transmission element according to one of Claims 6, 7 or 8 are provided.
Further advantages of the invention are obtained from the description following. In this description, the invention is explained in greater detail with reference to an illustrative embodiment shown in the drawing, in which:
FIG. 1 shows a particularly simple embodiment of a tripping device for circuit breakers,
FIG. 2 shows a tripping device with intermediate lever and additional compression spring,
FIG. 3 shows a tripping device comprising a first variant of a transmission element, and
FIG. 4 shows a tripping device comprising a second variant of a transmission element.
The same reference numbers are used for the same elements in the figures.
In FIG. 1, the tripping device 1 of a circuit breaker is shown in section. The structure of such a circuit breaker is known per se and can be seen, for example, in Swiss Patent Application No. 03 147/87-0. The tripping device 1 consists of a contact lever 2, a spring-loaded tripping lever 3 and a wire-shaped tripping element 4. The tripping element 4 is fixed in location with its end (not shown) and attached to the tripping lever 3 with its other end. The tripping lever 3 is rotatably supported on a linking piece (only partly visible). A leaf spring 6 is permanently joined to the linking piece 5 and forms the actual contact of the circuit breaker with its other end. In the housing wall 7 of the circuit breaker, a housing rib 8 in the form of an open rectangle (U shape) is provide
REFERENCES:
patent: 4205293 (1980-05-01), Melton
patent: 4263573 (1981-04-01), Melton
patent: 4713643 (1987-12-01), Baum et al.
Broome H.
Weber AG
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