DE102015213375A1 - Thermal overload tripping device and protective switching device - Google Patents

Abstract

The thermal overload tripping device (10) according to the invention for an electromechanical protective switching device (1) has a tripping element (11) which can be heated directly or indirectly by an electric current. The triggering element (11) has at a first end (12) an attachment point by means of which the triggering element (11) in a housing (2) of the protective switching device (1) can be fastened. Furthermore, a second end (13) of the trigger element (11) is designed as a free end, which is movable relative to the fastening point when heated due to the thermal expansion of the trigger element (11) to act upon Übersachreiten a predefined threshold on a Entklinkungsstelle the circuit breaker (1) , The triggering element (11) is formed in one piece and therefore represents a cost-effective replacement for a thermobimetal formed of a plurality of materials. It can be heated directly or indirectly, so that in this respect a simple adaptation to existing constructions is possible. The triggering element (11) can be fastened to the housing (2) of the protective switching device (1) at its first end (12) and expands when the temperature increases, wherein it is supported at a further contact point in the housing (2). In this case, mechanical stresses occur between the contact point and the attachment point, as a result of which the triggering element (11) deforms in this area. This deformation leads to a movement of the second, free end (13) of the trigger element (11), which is adapted to act on the Entklinkungsstelle the protective switching device (1) and thus to trigger the protection device (1).

Description

The present invention relates to a thermal overload tripping device for an electro-mechanical protection device, in particular for a circuit breaker or a circuit breaker. Furthermore, the present invention relates to an electro-mechanical protection device, in particular a circuit breaker or a circuit breaker, with such a thermal overload tripping device.

Thermal overload tripping devices are used in electromechanical circuit breakers - for example in a circuit breaker or in a circuit breaker - to interrupt a flow of current when the electrical current exceeds a predetermined current for a certain predefined period of time. Such protective switching devices are also referred to as overcurrent protection devices, which open the current path after a certain time in case of overload or short circuit and thus interrupt the flow of current. In this way, overcurrent protective devices protect electrical lines, electrical loads or consumers connected to the overcurrent protection devices against damage due to excessive heating, which would result from the overcurrent flowing over a prolonged period. An overcurrent can be caused by an overload or by a short circuit.

Overcurrent protection devices can react differently depending on the requirement profile: for example, the reaction time for triggering the protective switching device depends on the current that occurs. In the event of an overload, the circuit is interrupted delayed. The predefined trip time is in the seconds range, but can also be in the hourly range if the overload is low. On the other hand, in the case of a short circuit in which a current of several thousand amperes can flow, the current flow must be interrupted within a few thousandths of a second.

Typical overcurrent protection devices are circuit breakers or circuit breakers. Overcurrent protection devices are generally used in electrical installations. Since these protective switching devices are usually mounted in an electrical distribution manifold, which is also referred to as a distribution box, side by side "in series", they are also referred to as DIN rail mounted devices.

A thermal overload tripping device is used in such an overcurrent protection device, for example for unlatching a switching mechanism. A strip of bimetallic strip is fixedly clamped at one end, i. fixedly connected to the housing of the overcurrent protection device. The strip of bimetallic strip may, upon appropriate heating, deflect at the opposing other end, thereby unlatching a unlatching point of the latch, thereby causing an opening of a contact point of the overcurrent protection device.

In principle, a bimetallic strip consists of two layers of different metals or metal alloys which are firmly connected to one another and which, however, have a completely different temperature expansion behavior from one another. This causes a portion of the bimetallic strip to expand more than the other area with a temperature change, so that the bimetallic strip is generally curved toward the area with the lower temperature expansion behavior. The strip of bimetallic strip is consequently a strip-shaped element which deforms in a predefined manner at a predefined temperature change. This temperature behavior is exploited in the design of the overload tripping device. However, thermostatic bimetals are expensive to produce and thus relatively expensive, which has a correspondingly negative effect on the manufacturing costs of the bimetallic strip, and thus the overload tripping device or the electro-mechanical protection device. In order to obtain the desired tripping characteristic, it is further necessary that mechanical play between the bimetal on the one hand, and the housing and the switching mechanism of the protective switching device on the other hand, to keep as low as possible. This requires a high degree of precision in the manufacture of the individual components and in the assembly of the overload tripping device and the protective switching device, which in turn is reflected in higher production costs.

It is therefore an object of the present invention to provide a thermal overload tripping device and an electro-mechanical protection device, which are characterized by lower production costs with the same functionality and switching capacity.

This object is achieved by the thermal overload trip device and the electro-mechanical protection device according to the independent claims. Advantageous embodiments are the subject of the dependent claims.

The thermal overload tripping device according to the invention for an electromechanical protective switching device, in particular for a circuit breaker or a circuit breaker, has a tripping element, which by a Electric power can be heated directly or indirectly. The triggering element has at a first end an attachment point, by means of which the triggering element can be fastened in a housing of the protective switching device. Furthermore, a second end of the triggering element is designed as a free end, which is movable relative to the fastening point when heated due to the thermal expansion of the triggering element to act upon Übersachreiten a predefined threshold value to a Entklinkungsstelle the circuit breaker. The triggering element is formed integrally.

The trigger element is integrally formed, i. It consists of a single material, and therefore represents a cost-effective replacement for the bimetallic strip, which is constructed of two different materials. It can be heated directly or indirectly, so that in this respect a simple adaptation to existing constructions is possible. Under a direct heating is to be understood as the direct current flow through the trigger element, while an indirect heating, for example, by a heating element or by the waste heat adjacent components arranged feasible.

The trigger element can be fastened at its first end to the housing of the protective switching device. When the temperature rises, the trigger element expands, being supported at a further point of contact in the housing. Since no free elongation is now possible between the point of contact and the attachment point, stresses occur in the release element with further elongation, whereby this deforms in the region between the point of contact and the attachment point. This deformation leads to a movement of the second, free end of the trigger element, which is adapted to act on the Entklinkungsstelle the circuit breaker and thus trigger the protection device.

In an advantageous further connection of the overload tripping device, the tripping element is formed from a material having a high thermal expansion coefficient. By using such a material with a high coefficient of thermal expansion, a more accurate adjustment of the tripping characteristic of the protective switching device is made possible.

In a further advantageous connection of the overload tripping device, the tripping element is formed from a metallic material.

Since a large number of metallic materials with material properties known in detail already exists, the selection of a material suitable for this application is made easier. Among the materials suitable for this purpose, there is again a large number of metallic materials which have a high thermal expansion coefficient and, moreover, are inexpensive to procure and process. Furthermore, metallic materials are good electrical conductors and therefore also suitable as directly heated trigger element.

In a further advantageous continuation of the overload tripping device, the free end is designed to act directly on the unlatching point of the protective switching device. The action of a bimetallic strip usually takes place on the unlatching point of the protective switching device with the aid of a bracket, for example a drawbar. By the triggering device acts directly on the Entklinkungsstelle, can be dispensed with the bracket as an additional coupling element, whereby the manufacturing costs can be further reduced.

In a further advantageous connection of the overload tripping device, the tripping element is U-shaped, with a first leg, a second leg and a connecting region connecting the two legs, wherein the first end at the end of the first leg, and the second end at the end of second leg is formed. Due to the u-shaped design, the trigger element can be installed to save space in the housing of the protective switching device, without having to make compromises in terms of the required absolute elongation. The tripping characteristic of the overload tripping device and of the protective switching device is thereby positively influenced.

In a further advantageous further connection, the overload tripping device has an adjustment element, by means of which a relative position of the tripping element relative to the housing of the protective switching device can be adjusted without play.

Due to the play-free adjustment of the triggering element during its installation in the housing of the protective switching device ensures that the triggering element is already supported at the beginning of the temperature increase at the further point of contact in the housing. Thus, the zero point of the force on the housing - and thus the change in shape of the trigger element at a temperature increase - exactly defined. In this way, the movement of the free end of the trigger element in response to the temperature change is exact, i. without offest, fixable. The tripping characteristic of the overload tripping device, and thus the protective switching device, is thus precisely adjustable.

In a further advantageous further connection of the overload tripping device has the Triggering one or more crushing points, which serve to adjust the relative position of the triggering element relative to the housing of the protective switching device.

By Quetschstellen, which are mounted as part of the assembly of the overload trip device or the trigger element in the housing of the protection device between the attachment point and the other point of contact, a longitudinal expansion of this section is achieved until the trigger element despite possible manufacturing tolerances backlash mounted in the housing of the protection device is. This type of backlash-free installation represents a simple and extremely cost-effective implementation possibility for adjusting the relative position of the tripping element relative to the housing, and thus in particular with respect to the Entklinkungsstelle of the protective switching device, is.

In a further advantageous further connection of the overload tripping device, the play-free adjustment of the relative position of the tripping element relative to the housing by means of an adhesive agent can be realized.

The use of an adhesive provides a further cost-effective alternative to the play-free mounting of the overload tripping device or the trigger element in the housing of the protective switching device. Here, a different area of the trigger element, preferably the further point of contact with the aid of an adhesive - for example an adhesive or a potting compound, such as a synthetic resin - firmly connected to the housing. A temperature increase thus results directly due to the elongation, i. without offset, to a force of the trigger element on the housing and vice versa, and in the further course of the temperature-related elongation to the desired deformation of the trigger element. In this way, a play-free mounting of the trigger element can be realized, so that the tripping characteristic of the overload tripping device, and thus of the protective switching device, can be set in a predefined manner.

In a further advantageous connection of the overload tripping device, the play-free adjustment of the relative position of the tripping element relative to the housing by means of an adjusting screw can be realized.

The use of an adjusting screw represents a further alternative to the play-free mounting of the overload tripping device or of the tripping element in the housing of the protective switching device. In this case, the further point of contact is formed by the adjusting screw, which is screwed into the housing until the tripping element mounted without play in the housing is. Thus, also in this case, an increase in temperature (due to the elongation associated therewith) results directly, i. without offset, to a force of the trigger element on the housing and vice versa, and thus to the desired deformation of the trigger element. In this way, the tripping characteristic in the context of assembly in a predefined manner is adjustable. If the adjusting screw is also accessible from the outside, a readjustment is also possible with the housing already assembled or already closed.

In a further advantageous connection of the overload tripping device, the adjustment element is arranged on the connection region of the tripping element. The arrangement of the adjusting element in the connecting region of the triggering element represents a space-saving realization possibility.

The electromechanical protective switching device according to the invention, in particular a circuit breaker or circuit breaker, has a thermal overload tripping device of the type described above.

With regard to the advantages of the electro-mechanical protection switching device according to the invention, reference is made to the above-described advantages of the overload tripping device according to the invention.

Several exemplary embodiments of the thermal overload tripping device or of the electromechanical protective switching device will be explained in more detail below with reference to the attached figures. In the figures are:

1 a first embodiment of the overload tripping device or the protective switching device;

2A and 2 B a second embodiment of the overload trip device or the protective switching device in different states;

3 A third embodiment of the overload tripping device or the protective switching device;

In the various figures of the drawing, like parts are always provided with the same reference numerals. The description applies to all drawing figures in which the corresponding part can also be recognized.

In 1 is a first embodiment of the thermal overload tripping device 11 or the electromechanical Protection switching device 1 in the triggered state shown schematically in a side view. The protective switching device 1 has a housing 2 on, wherein the front housing shell has been omitted in the drawing to give a detailed insight into the structure of the protective device 1 to enable. In the left and right edge of the case 2 is in each case an electrical connection terminal 8th arranged over which the protective device 1 with external electrical leads (not shown) can be contacted. In the upper area, in the installed state of the protective device 1 the front corresponds, is an actuator 3 for manual operation - ie for switching on and off - the protective switching device 1 arranged. The actuator 3 is with a switching mechanism 4 of the protective switching device 1 mechanically coupled. Below the switching mechanism 4 is a switching contact 5 arranged, which with the help of the switching mechanism 4 operated, ie can be opened and closed. In the presentation of the 1 is the switching contact 5 opened, the actuator 3 of the protective switching device 1 is accordingly in its OFF position. Furthermore, the protective switching device 1 fastener 9 on, which on a front side opposite the rear side of the housing 2 are arranged. With the help of these fasteners 9 the protective switching device on a support member, such as a DIN rail (not shown), fastened.

In the event of a short circuit, the protective switching device 1 a so-called short-circuit tripping device 6 on. The high short-circuit current generates a mechanical trip signal and the switching mechanism 4 transferred, causing the switching mechanism 4 is triggered. As a result of this triggering finally the switching contact 5 open. Accordingly, the actuator takes 3 its OFF position. Below the short-circuit tripping device 6 is an arc extinguishing device 7 arranged. When opening the current-carrying switching contact 5 First, an arc is created, which is to be extinguished in the direction of the arc extinguishing device 7 where it is finally deleted.

In the event of an electrical overload, the protective switching device 1 a thermal overload tripping device 10 on, which at the in 1 illustrated protective device 1 between the arc extinguishing device 7 and the right terminal 8th is arranged. The thermal overload tripping device 10 has a trigger element 11 which, in turn, at its first end 12 has an attachment point, with the help of the triggering element 11 in the case 2 of the protective switching device 1 is fastened. A second end 13 of the trigger element 11 is designed as a free end, which when heated due to the thermal expansion of the trigger element 11 is movable relative to the attachment point to Übersachreiten a predefined threshold value to a Entklinkungsstelle the switching mechanism 4 of the protective switching device 1 act. To the trigger element 11 free of play in the housing 2 of the protective switching device 1 To mount, it has several pinch points 17 on, which in a region between the attachment point and another point of contact of the trigger element 11 with the housing 2 are arranged. In the presentation of the 1 is this further point of contact at a central portion of the trigger element 11 , which is arranged in the mounted state near the rear side of the housing formed. Through the pinch points 17 , which is part of the assembly of the overload tripping device 10 or the trigger element 11 in the case 2 of the protective switching device 1 be placed between the attachment point and the further point of contact, a longitudinal expansion of this section is achieved until the trigger element 11 despite possible manufacturing tolerances clearance in the housing 2 of the protective switching device 1 is mounted. The number of pinch points 17 can vary and depends on the manufacturing tolerances of the components to be mounted, ie the housing 2 and the trigger element 11 , from.

With the help of the pinch points 17 is the relative position of the trigger element 11 opposite the housing 2 - And thus in particular with respect to the Entklinkungsstelle the circuit breaker 1 - adjustable without backlash. This ensures that the trigger element 11 already at the beginning of its temperature-related elongation at the further point of contact in the housing 2 supported. This results in a temperature increase due to the elongation of the trigger element 11 directly, ie without offset, to a mechanical stress in the area between the attachment point and the other point of contact. This will cause the relevant section of the trigger element 11 reversibly deformed, ie it is bent to reduce this tension at least partially. However, this deformation requires a movement of the free second end 13 of the trigger element 11 , which points to the unlatching point of the protective switching device 1 acts. Due to this structural design of the trigger element 11 is ensured that the movement of the free end 13 of the trigger element 11 depending on the temperature change exactly, ie without offset, determinable. The tripping characteristic of the overload tripping device 10 - And thus the protective switching device 1 - Can thus be set exactly.

The term "offset" is to be understood that the temperature-related elongation of the release element 11 First, the resulting from the assembly game between the triggering element 11 and the housing 2 compensates before the trigger element 11 the housing 2 touched at the other touch point at all. Only from this time of contact, the trigger element can 11 supported on the further point of contact, so that builds up at a further elongation strain, a mechanical stress, resulting in the desired deformation of the trigger element 11 leads. This relationship can also be graphically illustrated: is the mechanical stress of the trigger element 11 plotted as a function of its elongation, the resulting curve passes through the origin of the coordinate system in a play-free mounting, while in the presence of a mechanical play between the housing 2 and the trigger element 11 does not go through the origin, and thus has an "offset".

In the in 1 the case shown is the trigger element 11 U-shaped. It has a first leg 14 , a second leg 15 , and a connecting region connecting the two legs 16 on. The first end 12 of the trigger element 11 is at the end of the first thigh 14 , the second end 13 at the end of the second leg 15 educated. The connection area 16 forms the further point of contact of the triggering element 11 with the housing 2 of the protective switching device 1 , Due to the u-shaped design, the trigger element 11 saves space in the housing 2 of the protective switching device 1 be mounted without compromising on the required absolute elongation - and thus the tripping accuracy - have to do.

In the 2A and 2 B is a second embodiment of the thermal overload tripping device 10 or of the electro-mechanical protective device 1 shown schematically, the two figures, the overload tripping device 10 or the electro-mechanical protective device 1 are shown schematically in different switching and operating states respectively in a side view. Both figures show the electromechanical protective device 1 a tripped state in which the actuator 3 is in its OFF position and the switching contact 5 is open. While in 2A the thermal overload tripping device 10 in a first switching or operating state, which corresponds to an operational state, is shown, shows 2 B the overload trip device 10 in a second tripped switching or operating state, in which the triggering element 11 is deformed due to the thermal expansion accordingly. The temperature-induced deformation of the trigger element 11 has the consequence that the second, free end 13 towards the fixed in the case 2 fixed first end 12 is bent. By the second end 13 coupled strap 20 will this movement of the second end 13 to the switching mechanism 4 transferred, whereupon the protective device 1 triggered and the switching contact 5 is opened.

That in the 2A and 2 B illustrated second embodiment differs from the in 1 illustrated first embodiment essentially in that the backlash-free mounting of the triggering element 11 in the case 2 of the protective switching device 1 with the help of an adjusting screw 19 is realized. The adjusting screw 19 is in the range of the fastener shown on the right 9 in the back of the case 2 screwed in so far that they are the connection area 15 of the trigger element 11 touched. In this way is also a backlash-free mounting of the trigger element 11 in the case 2 of the protective switching device 1 realizable.

In 3 is a third embodiment of the thermal overload tripping device 10 or of the electro-mechanical protective device 1 shown schematically in a side view. This representation resembles strongly the representations in the 1 and 2 , but with the difference that the backlash-free mounting of the trigger element 11 in the case 2 of the protective switching device 1 in this third embodiment with the aid of an adhesive agent 18 is realized. This may be an adhesive or - to compensate for larger differences in length - a potting compound, such as a synthetic resin, act. Regardless of which adhesive is used, thereby a second fixation of the trigger element 11 in the case 2 realized, at which the triggering element 11 in the case of a temperature-related elongation directly, ie without offset, can support. The case between the trigger element 11 and the housing 2 occurring mechanical stresses lead in the course to the predefined deformation of the first leg 14 trigger element 11 , and thus the predefined movement of the second leg 15 trained free second end 13 , The use of the adhesive 18 thus represents another cost-effective alternative to the play-free mounting of the overload tripping device 10 or the trigger element 11 in the case 2 of the protective switching device 1 represents.

In the representations of the 1 to 3 is the free second end 13 of the trigger element 11 always over a hanger 20 with the switching mechanism 4 of the protective switching device 1 coupled. However, it is also possible, the trigger element 11 in the area of its free second end 13 to be designed so that it directly and directly to the unlatching point of the switching mechanism 4 of the protective switching device 1 acts. In this case, on the hanger 20 be waived.

LIST OF REFERENCE NUMBERS

1

Protection device

2

casing

3

actuator

4

switching mechanism

5

switching contact

6

Short trip device

7

Arc-extinguishing device

8th

terminal

9

fastener

10

Overload tripping device

11

triggering element

12

first end

13

second end / free end

14

first leg

15

second leg

16

connecting area

17

crushing

18

adhesives

19

adjustment

20

hanger

Claims (11)

Thermal overload tripping device ( 10 ) for an electromechanical protective device ( 1 ), in particular for a circuit breaker or a circuit breaker, - with a tripping element ( 11 ), which is directly or indirectly heated by an electric current, - in which the trigger element ( 11 ) at a first end ( 12 ) has an attachment point by means of which the trigger element ( 10 ) in a housing ( 2 ) of the protective switching device ( 1 ), - at which a second end ( 13 ) of the trigger element ( 11 ) is designed as a free end, which when heated due to the thermal expansion of the trigger element ( 11 ) is movable relative to the fastening point in order, when passing a predefined threshold value on a Entklinkungsstelle the protective switching device ( 1 ), characterized in that the triggering element ( 11 ) is integrally formed. Overload trip device ( 10 ) according to claim 1, characterized in that the triggering element ( 11 ) is formed of a material having a high thermal expansion coefficient. Overload trip device ( 10 ) according to one of the preceding claims, characterized in that the triggering element ( 11 ) is formed of a metallic material. Overload trip device ( 10 ) according to one of the preceding claims, characterized in that the free end ( 13 ) for direct action on the unlatching point of the protective switching device ( 1 ) is trained. Overload trip device ( 10 ) according to one of the preceding claims, characterized in that the triggering element ( 11 ) is U-shaped with a first leg ( 14 ), a second leg ( 15 ) and one the two legs ( 14 . 15 ) connecting area ( 16 ), the first end ( 12 ) at the end of the first leg ( 14 ), and the second end ( 13 ) at the end of the second leg ( 15 ) is trained. Overload trip device ( 10 ) according to one of the preceding claims, characterized in that the overload release device ( 11 ) has an adjustment element, by which a relative position of the trigger element ( 11 ) opposite the housing ( 2 ) of the protective switching device ( 1 ) is adjustable without play. Overload trip device ( 10 ) according to claim 6, characterized in that the triggering element ( 11 ) one or more pinch points ( 17 ), which for play-free adjustment of the relative position of the trigger element ( 11 ) opposite the housing ( 2 ) of the protective switching device ( 1 ) serve. Overload trip device ( 10 ) according to claim 6, characterized in that the play-free adjustment of the relative position of the trigger element ( 11 ) opposite the housing ( 2 ) with the aid of an adhesive ( 18 ) is feasible. Overload trip device ( 10 ) according to claim 6, characterized in that the play-free adjustment of the relative position of the trigger element ( 11 ) opposite the housing ( 2 ) with the aid of an adjusting screw ( 19 ) is feasible. Overload trip device ( 10 ) according to one of claims 6 to 9, characterized in that the adjustment element at the connection region of the trigger element ( 11 ) is arranged. Electromechanical protective device ( 1 ), in particular circuit breaker or circuit breaker, which a thermal overload tripping device ( 10 ) according to one of claims 1 to 10.

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