DE1017253B - Temperature-dependent electrical switching device with a magnetic circuit, especially for telecommunications systems - Google Patents

Description

The invention relates to a magnetic temperature-dependent electrical switching device with a Magnetic circuit, especially for telecommunications systems, in which the effect of a pull-off force on one in one Magnetic circuit inserted and capable of mechanical and / or electrical circuits through member Changing the magnetic conductivity of the magnetic circuit is controlled. With known institutions this type is the change in magnetic conductivity by introducing a medium of another Conductivity in the path of the magnetic lines of force or through a mechanically acting interrupter device causes in the magnetic circuit. In both cases this must either be done manually or complex devices are required for this. In turn, own other known devices a medium in the magnetic circuit, the magnetic conductivity of which is temperature-dependent. Apart from that of the fact that special material usually has to be used as a medium is in such institutions laying in consideration of the course of the conductivity-temperature characteristics of this material the working point in a certain temperature range, which is often only through special measures can be achieved, required.

In contrast, the purpose of the invention is to create an automatic switching device, which stands out through safe mode of operation with low manufacturing costs. This is according to the invention achieved in that a thermally acting switch which interrupts this in the magnetic circuit is inserted. If the thermal switch responds at a certain temperature, it opens the Magnetic circuit, so changes the conductivity of the circuit. Thereby the magnetic attraction force, which acts on the movable switching element is reduced in such a way that the one which also acts on the switching element Pull-off force, which in the normal state of the magnetic circuit is smaller than the magnetic pull-in force is, takes effect and moves the switching element.

It is particularly expedient to design the thermal switch in the form of a bimetal strip which is heated from the outside by direct current flow or by heating and which bends depending on the expansion coefficients of its two materials. Although it is already known to have circuits carried out by the bimetal strips themselves, the selected dimensions of the bimetal strips of a direct circuit set relatively narrow limits with respect to the number of circuits that can be carried out during a stroke. If, however, according to the invention, the thermal switch is inserted into the magnetic circuit and under-temperature-dependent
electrical switchgear

with a magnetic circuit,
especially for telecommunications systems

Applicant:
Siemens & Halske Aktiengesellschaft,

Berlin and Munich,
Munich 2, Witteisbacherplatz 4

Herbert Mahnke, Munich,
has been named as the inventor

if this breaks due to the thermal effect, the thermal switch triggers the circuit, this one but is carried out by the movable member, which in turn provides the power for the circuits got to. This force is available to the movable switching element in the form of the pull-off force, for example a spring, available without any essential components of the force to overcome the attraction force of the magnetic circuit must be used. The dimensioning of the pull-off force is only through the required switching capacity, with the pull-off force in the idle state of the switching device must be less than the attraction force of the magnetic circuit. Only when the magnetic circuit is open and so that the tightening force is weakened, the pull-off force comes into effect.

To avoid an undesired response of the thermally acting switch due to room temperature fluctuations to prevent a second bimetallic strip can according to a development of the inventive concept with the same thermal properties can be connected in parallel to the first, so that it is arranged is that it remains unaffected by the heating triggering the circuit. When the ambient temperature changes however, it performs the same movements as the first bimetal strip and makes according to Its special arrangements in the magnetic circuit make the bending of the first strip ineffective.

If, in addition to the normal thermal release, a quick release is required, then according to a further invention the magnetic circuit

709 '700/32?

Claims (6)

Electromagnet added, the force effect of which is opposite to that of the magnetic circuit and which is dimensioned so that it allows the pulling force acting on the switching element to take effect immediately. By appropriate arrangement of the magnet generating the flux in the magnetic circuit in relation to the electromagnet, the mutual repulsion of the two opposing magnets can also be used to support the pull-off force. If a heating winding is provided for the thermally acting switch, it is particularly useful to use it at the same time as an excitation winding for the electromagnet. The drawing shows the basic representation of an exemplary embodiment of the invention. The magnetic circuit consists of the permanent magnet 1, which is also designed as a movable switching element, and parts 2 and 3, of which part 2 is a bimetallic strip that is heated via the winding 4. If, instead of the magnetic conductive part 3, a bimetal member with the same thermal data and the same bending direction as the part 2 is also inserted, the influence of a change in room temperature on the part 2 is compensated for. If an electromagnet is added for quick release, the heating winding 4 can simultaneously serve as an excitation winding. The pull-off force P acts on the switching element 1, which in the normal state of the magnetic circuit is smaller than the magnetic attraction force that attracts the switching element 1. Only when the magnetic circuit at point 5 is opened by heating the part 2 by bending it does the magnetic attraction force drop below the value of the withdrawal force P, and the switching element 1 is withdrawn. This movement is used in a manner known per se to carry out circuits. If there is an electromagnet that counteracts the magnetic force, the magnetic attraction force can also be weakened to below the value of the withdrawal force P by its excitation. If, as in the example shown, the electromagnet is arranged so that it can move relative to the magnet 1 generating the magnetic flux, the pull-off force P is further supported by the force with which the electromagnet and magnet 1 repel each other. Patent λ ν s ρ r ü c ηε: 1. Temperature-dependent electrical switching device with a magnetic circuit, in particular for telecommunication systems in which the effect of a pull-off force on one inserted in a magnetic circuit and a member capable of mechanical and / or electrical circuits through modification the magnetic conductivity of the magnetic circuit is controlled, characterized in that that a thermally acting switch which interrupts this is inserted into the magnetic circuit is. 2. Switching device according to claim 1, characterized in that the switch consists of a bimetal strip (2) exists. 3. Switching device according to claim 2, characterized in that the bimetal strip (2) a second, similar bimetal strip (3) is arranged in parallel. 4. Switching device according to claim 1, characterized in that an electromagnet is inserted into the magnetic circuit (1, 2, 3), the force of which is opposite to that of the magnetic circuit (1, 2, S). 5. Switching device according to one of claims 1 to 3 and 4, characterized in that the Heating winding (4) for the thermal switch (2) at the same time as the excitation winding for the Serves electromagnet. 6. Switching device according to claim 4, characterized in that the magnetic flux in the magnetic circuit generating magnet (1) is arranged movable to the electromagnet. Considered publications:
German Patent No. 906 829;
British Patent Nos. 517 572, 473 589. 1 sheet of drawings © 709 700/327 10.57