Multi-phase overload protection device

Abstract

Multiphase overload protection device, with a switching contact, with a number of bending elements (1, 2, 3), wherein each phase is assigned a bending element (1, 2, 3) which bend depending on the current flowing in the respective phase, with a transmission actuator (4) which is coupled to the bending elements (1, 2, 3), and which comprises a pair of longitudinally displaceable sliding elements (5, 6) and a pivot lever (7), wherein, when a first of the sliding elements (5) is prevented from displacing by one of the bending elements (1) and the other sliding element (6) displaces, the pivot lever (7) pivots about a pivot axis (8) fixed in the other sliding element (6) to actuate the switching contact, characterized in that two spaced-apart guide pins (25, 26) are mounted on the pivot lever (7) and each of which bears against one of the sliding elements (5, 6). are formed by support on the guide pins (25,26) a gap (11) extending perpendicular to the direction of displacement between the two sliding elements (5, 6) is formed, and that a collar-shaped projection (9) with an arcuate cam surface (10) is formed on the pivot lever (7), which is supported on a support surface (12) of one of the sliding elements (5) and can roll on the support surface (12) when the two sliding elements (5, 6) are displaced in opposite directions, thereby maintaining the gap (11) when the two sliding elements (5, 6) are displaced in opposite directions.

Description

[0001] The invention relates to a multi-phase overload protection device according to the preamble of claim 1 and a transmission actuator for a multi-phase overload protection device according to the preamble of claim 4.

[0002] Such overload protection devices can be familiar multi-phase overload relays, motor protection switches, circuit breakers or other thermal overcurrent protection devices.

[0003] German patent DE 2 329 642 A discloses a multi-phase relay for controlling contactors. This prior art describes a multi-phase relay that responds more quickly to overload conditions that cause phase asymmetry than to overload conditions that do not affect phase symmetry. A sliding element arrangement is disclosed for converting the bimetallic bending into a tripping movement of the trip mechanism.

[0004] DE 7 422 977 U discloses a multi-phase thermally delayed overcurrent relay. The overcurrent relay has bimetallic strips which are operatively connected to sliders that can be displaced relative to each other when the bimetallic strips are deflected differently, and which are coupled via a differential lever with which a tripping device can be actuated.

[0005] Such a multi-phase overload protection device has a switching contact and a number of bending elements, with each phase being assigned a bending element that bends depending on the current flowing in the respective phase. It further has a transmission actuator coupled to the bending elements, comprising a pair of longitudinally displaceable sliding elements and a pivot lever, wherein, when a first of the sliding elements is prevented from displacing by one of the bending elements and the other sliding element displaces, the pivot lever pivots about a pivot axis fixed in the other sliding element to actuate the switching contact.

[0006] Such a thermal overcurrent relay has one thermal bimetal strip as a bending element for each phase. The thermal bimetal strips of the three phases are coupled to a switch lock for opening contact points via a suitable transmission actuator, a slide with a pivot lever. When an overcurrent occurs and all thermal releases, which are normally designed as thermal bimetal strips, are triggered and bend, the movement of the thermal bimetal strips is transmitted to the switch lock via the pivot lever coupled to the slide. When all thermal bimetal strips are triggered, a specific force is exerted on the switch lock via the transmission actuator, thus ensuring reliable tripping.

[0007] A so-called phase failure occurs when the voltage or current has failed in one or two phases, but is still flowing in at least one other phase. Even in such a phase failure, tripping must be possible. Therefore, the slider is composed of two sliding elements that are movable relative to each other. Additionally, a pivot lever is provided, which is articulated to the sliding elements. This ensures that if one sliding element is held in place due to the thermobimetallic switch failing to activate, the other element moves and actuates the pivot lever. This causes the actuating end of the pivot lever, which acts on the trip lever of the switch via the moving sliding element, to travel a greater distance, thus ensuring reliable tripping.US Patent 4,806,897 discloses such an overload relay with two sliding elements, where the two sliding elements touch one of their longitudinal sides in a common sliding plane and can slide against each other with friction. In the event of a phase failure, both sliding elements perform an opposing sliding movement along the sliding plane. This frictional sliding generates a frictional force that must be overcome by the bending element. The thermal release, the bending element, must therefore be designed for a higher tripping force.

[0008] The sliding elements are designed for high temperature resistance in industrial applications of the overload relay. Therefore, they are typically manufactured as stamped parts from epoxy resin fabric, as this is a cost-effective solution for producing high-temperature-resistant components. Stamped from an epoxy resin fabric, the contact surface along which the two sliding elements move in opposite directions is rough, thus increasing the frictional force that the thermal release must overcome.

[0009] The object underlying the present invention is therefore to provide a multi-phase overload protection device and a transmission actuator for a multi-phase overload protection device in which, in the event of a phase failure, the force required to trigger the thermal release is reduced.

[0010] The problem is solved according to the invention with regard to the overload protection device by an overload protection device with the features of claim 1 and with regard to the transmission actuator by a transmission actuator with the features of claim 4.

[0011] According to the invention, two guide pins spaced apart from each other and each supported on one of the sliding elements are formed on the pivot lever, wherein a gap extending perpendicular to the direction of displacement between the two sliding elements is formed by support on the guide pins, and that a collar-shaped projection with an arcuate cam surface is formed on the pivot lever, which is supported on a support surface of one of the sliding elements and can roll on the support surface when the two sliding elements are displaced in opposite directions, and thereby a maintenance of the gap is effected when the two sliding elements are displaced in opposite directions.

[0012] In the overload protection device according to the invention, the two sliding elements support each other against the guide pins of the pivot lever. This creates a gap between the two sliding elements 5 and 6, which ensures that no sliding friction force has to be overcome between the two sliding elements when they are moved in opposite directions. The additional collar-shaped projection provided by the invention ensures that, even during a phase failure, the two sliding elements are held at a distance from each other during a phase failure and do not move towards each other, thus preventing them from potentially coming into frictional contact.The two opposing longitudinal sides of the sliding elements do not touch when they move in opposite directions, and the collar-shaped projection keeps them at a constant distance from each other even when moving in opposite directions, preventing them from touching. Therefore, the thermal release mechanism no longer has to overcome any sliding friction force between the two sliding elements.

[0013] When the two sliding elements are moved in opposite directions, the collar-shaped projection with its arcuate cam surface rolls along the support surface of the opposing sliding element. The rolling friction force that must be overcome is many times lower than the sliding friction force that must be applied in arrangements known in the prior art.

[0014] Overall, the inventive solution significantly reduces the contribution of frictional force during the counter-rotating movement of the two sliding elements. This allows the thermal release to be designed for a lower trigger force. In particular, it can be made smaller and more compact. As a further consequence of the reduced power consumption of such a compact thermal release, overlapping current ranges or even a reduced number of device variants can be created. This benefits customers, as they need to use fewer different device variants. It also benefits the device manufacturer, as they need to provide and maintain fewer device variants.

[0015] According to an advantageous embodiment of the invention, the support surface is located on the first sliding element, which is held in place by one of the bending elements in the event of a phase failure.

[0016] According to an advantageous embodiment of the invention, the center point of the arc of the arc-shaped cam surface lies in the pivot axis of the pivot lever. This further contributes to ensuring that the two sliding elements do not touch each other and, thanks to the collar-shaped projection, are held at an unchanged distance from each other even when moved in opposite directions, without touching.

[0017] Further advantages and advantageous embodiments of the invention are characterized in the dependent claims.

[0018] The invention is explained below with reference to the embodiment shown in the drawing.

[0019] The figures and description serve to improve understanding of the subject matter. Objects or parts of objects that are essentially the same or similar may be provided with the same reference numerals. The figures are merely a schematic representation of one possible embodiment of the invention.

[0020] They show: Fig. 1 a perspective view of a transmission actuator according to the invention with three bending elements, Fig. 2 a view of a transmission actuator according to the invention in the rest position, Fig. 3 a view of a transmission actuator according to the invention in the event of a phase failure in the triggered position.

[0021] First, the Fig. 1 and Fig. 2 considered together. Fig. Figure 2 shows a transmission actuator 4 as used in a three-phase overload protection device. The overload protection device itself is not shown here, as its principle is known. The transmission actuator 4 consists of two sliding elements 5, 6 and a pivot lever 7. The sliding element 5 and the sliding element 6 are identical in this example. They each have a longitudinally extended base body 13, 13', from which three fingers 14, 14'; 15, 15'; 16, 16' project perpendicular to its longitudinal direction and lie in a common plane. A first finger 14, 14' is flush with the narrow side of the longitudinally extended base body 13, 13'. A second finger 15, 15' is attached approximately in the middle of the longitudinally extended base body 13, 13'. A third finger 16, 16' is attached a short distance from the second narrow side 17 of the elongated base body 13, 13'.Each of the fingers 14, 14'; 15, 15'; 16, 16' has a protrusion 18, 18'; 19, 19'; 20, 20' formed on one side, here on the side pointing towards the second narrow side 17, which forms a stop for a projection of a bending element 1, 2, 3 of the thermal release.

[0022] The formation of the transmission actuator 4 can be visualized as follows: initially, both sliding elements 5 and 6 lie congruently on top of each other, with sliding element 5 at the bottom and sliding element 6 on top of it. Sliding element 6 is then rotated 180° and subsequently moved upwards in the direction of the extension of fingers 14, 15, and 16 on the first sliding element 5, parallel to the longitudinal axis of the elongated base 13, until the free narrow side 21 of the first finger 14 comes to rest over the free longitudinal edge 22 at the free end 23 of the elongated base body 13. A gap 11 is formed between the free narrow side 21 of the first finger 14 and the free longitudinal edge 22 at the free end 23 of the elongated base body 13. This gap 11 prevents the two sliding elements 5 and 6 from sliding against each other.The protrusions 18, 20'; 19, 19'; 20, 18' of the now adjacent fingers 14, 16'; 15, 15'; 16, 14' each point towards each other and form a gap between them. The free end of each of the thermobimetals 1, 2, 3 is coupled into this gap. The two sliding elements 5, 6 are thus movably assembled relative to each other.

[0023] How Fig. Figure 1 shows that the bending elements, the thermobimetals, 1, 2, 3, are arranged one behind the other or next to each other, such that their central longitudinal axes lie in a plane and their flat sides are perpendicular to it; the bending of all thermobimetals occurs in the direction of the plane extension, in the view according to the Fig. 1 to 3 in the direction of arrow P, from right to left.

[0024] Additionally, a pivot lever 7 is provided, which is articulated to the sliding elements 5, 6. The pivot lever 7 is approximately in the shape of a rectangular disc with a recess 24 near one of the corners. The free edge 28 of the recess 24 forms the actuating end 28 of the pivot lever 7. Upon release, the transmission actuator 4 acts on the release lever of the switch lock via the actuating end 28 of the pivot lever 7, as described below.

[0025] In the view of Fig. In sections 1 to 3, the pivot lever is located behind the two sliding elements 5 and 6 in the viewing direction; it is partially obscured by them, as indicated by the dashed lines. Two cylindrical guide pins 25 and 26 are attached to the pivot lever 7, projecting perpendicular to the plane of the disk. The two pins 25 and 26 are spaced apart.

[0026] A first pin 25 is guided in a recess in the base body 13 of the first sliding element 5 and is supported against the base body 13 of the first sliding element 5.

[0027] The second pin 26 is guided in an elongated slot 27' in the second finger 15' of the second sliding element 6 and is thus supported against the base body 13' of the second sliding element 6. The elongated slot 27' is open on its longitudinal side facing the first sliding element 5. The elongated slot 27 in the first sliding element 5 is therefore not occupied.

[0028] The distance between the two pins 25, 26 is chosen such that, due to the support of the two pins 25, 26 on the sliding elements 5, 6, a gap 11 is formed between them as described above.

[0029] Furthermore, a collar-shaped projection 9 is located on the pivot lever 7, projecting from it in the same direction perpendicular to the plane of the pivot lever 7 as the two pins 25, 26. The collar-shaped projection 9 has an arcuate contour with an arcuate cam surface 10, which is aligned with the first slide element 5. The center of the arc of the arcuate cam surface 10 coincides with the pin 26.

[0030] In an undisturbed triggering scenario, all three bending elements 1, 2, 3 bend outwards in the direction of arrow P, as shown in the view of the Fig. 2 to the left. This moves the transmission actuator 4 parallel to the left with the pivot lever 7. Both the first sliding element 5 and the second sliding element 6 are moved in the direction of arrow P. The actuating end 28 is moved to the left until it engages the release lever of the switch lock and moves it into its release position.

[0031] The Fig. Figure 3 shows the situation when the phase associated with bending element 1 fails. Therefore, if an overcurrent occurs, bending element 1 does not bend, while the other two bending elements, 2 and 3, do bend. Bending element 1 holds the first sliding element 5 against the curvature 20 and prevents it from shifting to the left.

[0032] The other two bending elements 2, 3 move the second slide element 6 via the protrusions 19', 20' to the second finger 15' and the third finger 16' of the second slide element 6, respectively, in the opposite direction to the first slide element 5 to the left. During this counter-clockwise movement of the two slide elements 5, 6, the pivot lever 7 is pivoted counterclockwise. The pin 26 forms the pivot axis 8 of the pivot lever 7 and is pivotably fixed in the elongated hole 27 on the second slide element 6. When the pivot lever 7 pivots counterclockwise, the pin 25 lifts off in the recess in the base body 13 of the first slide element 5 to compensate for any height difference.

[0033] The collar-shaped projection 9 prevents the second sliding element 6 from lowering towards the first sliding element 5. The collar-shaped projection 9 rests with its arcuate cam surface 10 on the support surface 12 of the first sliding element 5, rolling on the support surface 12 during the opposing sliding movement of the two sliding elements 5, 6 relative to each other. Advantageously, the center of the arc of the arcuate cam surface 10 coincides with the pivot axis 8, formed by the pin 26. This facilitates low-friction rolling. As a result, the distance between the two sliding elements 5, 6 is maintained, the gap 11 remains, and during the opposing sliding movement of the two sliding elements 5, 6 relative to each other, only the slight rolling friction force connecting the arcuate cam surface 10 to the support surface 12 needs to be overcome.

[0034] By pivoting the swivel lever 7, even in the event of overcurrent tripping during phase failure, the actuating end 28 of the swivel lever 7 is moved to the left until it meets the release lever of the switch lock and can move it into its tripping position. Reference symbol list 1 bending element 2 Bending element 3 Bending element 4 transmission actuator 5 first sliding element 6 second sliding element 7 swivel levers 8. Swivel axis of the swivel lever 9 collar-shaped protrusion 10 arc-shaped cam surfaces 11 column 12 support surface 13 basic bodies 13' Base body 14 first finger 14' first finger 15 second finger 15' second finger 16 third finger 16' third finger 17 second narrow side 18 Curvature 18' Curvature 19 Curvature 19' Curvature 20 bulge 20' Curvature 21 free narrow side 21' free narrow side 22 free longitudinal edge 22' free longitudinal edge 23 free end of the base body 23' free end of the base body 24 indentations 25 first lead pin 26 second lead pin 27 elongated holes 27' slotted hole 28 End of operation P arrow P' Arrow

Claims

[1] Multi-phase overload protection device, with a switching contact, with a number of bending elements (1, 2, 3), each phase being assigned a bending element (1, 2, 3) which bends depending on the current flowing in the respective phase, with a transmission actuator (4) which is coupled to the bending elements (1, 2, 3) and which comprises a pair of longitudinally displaceably mounted slide elements (5, 6) and a pivoting lever (7), wherein, when a first of the slide elements (5) is prevented from moving by one of the bending elements (1) and the other slide element (6) moves, the pivoting lever (7) pivots about a pivot axis (8) fixed in the other slide element (6) to actuate the switching contact, characterized byin that two guide pins (25, 26) are formed on the pivot lever (7), which are spaced apart from one another and are each supported on one of the slide elements (5, 6), wherein a gap (11) extending perpendicular to the direction of displacement between the two slide elements (5, 6) is formed by support on the guide pins (25, 26), and in that a collar-shaped projection (9) with an arcuate cam surface (10) is formed on the pivot lever (7), which projection is supported on a support surface (12) of one of the slide elements (5) and can roll on the support surface (12) when the two slide elements (5, 6) are displaced in opposite directions, thereby maintaining the gap (11) when the two slide elements 5, 6 are displaced in opposite directions. [2] Multi-phase overload protection device according to claim 1, characterized bythat the support surface (12) is located on the first slide element (5), which is held by one of the bending elements (1, 2, 3) in the event of a phase failure. [3] Multi-phase overload protection device according to claim 1, characterized by that the center of the arc of the arc-shaped cam surface (10) lies in the pivot axis (8) of the pivot lever (7). [4] Transfer actuator (4) for a multi-phase overload protection device with a number of bending elements (1, 2, 3), each phase being assigned a bending element (1, 2, 3) which bends depending on the current flowing in the respective phase, the transfer actuator (4) being coupled to the bending elements (1, 2, 3) and comprising a pair of longitudinally displaceably mounted slide elements (5, 6) and a pivoting lever (7), wherein, when a first of the slide elements (5) is prevented from moving by one of the bending elements (1) and the other slide element (6) moves, the pivoting lever (7) pivots about a pivot axis (8) fixed in the other slide element (6) to actuate the switching contact, characterized byin that two guide pins (25, 26) are formed on the pivot lever (7), which are spaced apart from one another and are each supported on one of the slide elements (5, 6), wherein a gap (11) extending perpendicular to the direction of displacement between the two slide elements (5, 6) is formed by support on the guide pins (25, 26), and in that a collar-shaped projection (9) with an arcuate cam surface (10) is formed on the pivot lever (7), which projection is supported on a support surface (12) of one of the slide elements (5) and can roll on the support surface (12) when the two slide elements (5, 6) are displaced in opposite directions, thereby maintaining the gap (11) when the two slide elements 5, 6 are displaced in opposite directions. [5] Transfer actuator (4) according to claim 4, characterized bythat the support surface (12) is located on the first slide element (5), which is held by one of the bending elements (1, 2, 3) in the event of a phase failure. [6] Transfer actuator (4) according to claim 4, characterized by that the center of the arc of the arc-shaped cam surface (10) lies in the pivot axis (8) of the pivot lever (7)

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