This Application is a Section 371 National Stage Application of International Application No. PCT/EP2014/051751, filed Jan. 30, 2014 and published as WO 2014/122056 A1 on Aug. 14, 2014, the contents of which are hereby incorporated by reference in their entirety.
Overvoltage protection devices having thermal disconnection apparatus have been known for years in the prior art. The function of a disconnection apparatus is, in the event of unacceptably high heating of the overvoltage protection unit, e.g. a varistor, to safely disconnect it from the electrical network before the arrestor suffers any damage.
Disconnection apparatus comprising solid sliders are known from EP 0 987 803 B1 and EP 0 905 839 B1. The respective slider is spring-loaded and each protect a varistor from unacceptable thermal heating. The closed position of the respective connection elements is fused by a solder. The solder is subjected to the constant spring preload force conveyed by the slider, which is a substantial disadvantage. Depending on the rating; i.e. the desired current-carrying capacity, a plurality of disconnection apparatus are required, which constitutes a disadvantage in terms of costs. It has furthermore been shown with the above prior art solutions that solder particles or particulate matter become entrained and form solder filaments during the disconnection process and the displacing motion of the slider, resulting in insufficient electrical disconnection.
The DE 295 19 313 U1 utility model indicates an overvoltage protection device having a thermal disconnection apparatus, wherein the disconnection apparatus is positioned separately from the actual varistor by means of a partition wall. The surge current carrying capacity of such a disconnection apparatus is too low from today's perspective and its solder joint subject to a constant spring preload force.
The known DE 2 220 264 A relates to a thermal protection or warning device in which actuation is blocked by a temperature-sensitive retaining element and the retaining element activates a slider as a result of melting upon a predetermined temperature being reached.
DE 1 515 019 A discloses a temperature limiter in which two leaf springs are soldered together by solder which melts upon a certain temperature being reached and are used particularly in fan heaters.
The generic DE 10 2007 042 991 B4 solves the task of specifying a further developed overvoltage protection device having a mechanical disconnection apparatus activated in the event of thermal overload, wherein the solder joint of the connection elements which releases upon disconnection is not to be constantly subjected to the effect of a mechanical force load. The known solution moreover exhibits a high surge current carrying capacity, wherein the surge current itself produces the contact pressure for the discharging process. The disconnection apparatus according to DE 10 2007 042 991 B4 is realized such that the feed to the voltage-limiting overvoltage protection units, particularly varistors, is formed by two conducting sections extending parallel in the end region and merging into a common solder joint fused by solder with surge current flowing through the sections in the same direction. Upon surge current, the respective sections of the leads, respectively brackets, attract the parallel current flow and the thereby associated effects of the force and at that time effect the desired increase in contact force on the solder joint. This makes it possible to dimension the solder joint solely to fix the sections of the brackets, which enables the mechanical dimensioning of the solder joint to be limited to an absolute minimum and thereby have it be particularly thermally sensitive. The spring of this respective disconnection apparatus, the function of which consists of displacing a solder between the current paths when the solder joint melts and thus interrupt the electric circuit, can be realized with lower spring force so as to result in lower constant loading of the solder joint. Since the slider drives directly into the solder joint upon disconnection, negative effects are prevented during the disconnection process and safe, voltage-free cut-off achieved.
Disadvantageous with respect to the DE 10 2007 042 991 B4 solution is the fact that the slider is functionally coupled with the visual signaling of the slider position and thereby a display of the functional properties of the disconnection apparatus. For this reason, the slider thus needs to be structurally designed so as to exhibit the most even, color-differentiated display area possible in order to make clear the respective functional state of the respective overvoltage protection device. Furthermore, the slider's direction of movement upon overload for disconnecting the varistors preferably utilized is predefined so that the position of a display window for identifying the state of movement of the slider is also structurally determined, which represents a disadvantage for example when the size of the respective overvoltage protection device is decreased.
Embodiments of the present invention relate to an overvoltage protection device comprising at least one overvoltage protection unit having at least one contact lug as well as a mechanical disconnection apparatus activated in the event of thermal overload, wherein the mechanical disconnection apparatus comprises a connection element able to be moved from a closed position into a current interrupting or voltage cut off position by a slider preloaded by a spring force.
The following will reference an embodiment as well as the figures in describing the invention in greater detail.
The figures thereby show:
The following description of the figures will use the same reference numerals in each case, wherein details recognizably repeated in the figures will not be reiterated multiple times without thereby limiting the nature of the invention or involving a nuance of valence with respect to individual structural elements.
Based on the above, it is thus the task of the invention to specify a further developed overvoltage protection device comprising at least one overvoltage protection unit having a mechanical disconnection apparatus which is or can be activated in the event of a thermal overload, which on the one hand exhibits positive effects in terms of current flow and the thereby associated forces upon a surge voltage and moreover enables functional separation of a visual indicator for the slider and its movement as necessary for the functional state of the overvoltage protection units employed. Furthermore, the possibility is provided to integrate a signaling device for monitoring the overvoltage protection unit status into the overvoltage protection device designed in particular as a plug-in component so that only minimum installation space is required and there is no appreciable mechanical loading of the thermal joint fused with solder or a thermally soluble adhesive.
One therefore proceeds from an overvoltage protection device comprising at least one overvoltage protection unit, particularly a varistor, wherein the overvoltage protection unit has at least one contact lug. The overvoltage protection device moreover comprises a disconnection apparatus which is activated upon thermal overload, wherein the disconnection apparatus in turn comprises a connection element able to be moved from a closed into a current-interrupting or voltage cut-off position by a slider preloaded by spring force, wherein the connection element consists of a pair of current-dividing metallic brackets, the ends of which directed toward the contact lug of the overvoltage protection unit extend in parallel and which receive the respective contact lug of the overvoltage protection unit between them. The closed position between the connection element and contact lug in the area of the parallel-extending ends of the brackets is fused by a solder joint or a thermally soluble adhesive or other similar means.
The far ends of the brackets from the contact lug of the overvoltage protection unit are connected together, enclosing a free space, and have a section in their further progression for external connector components, whereby the cited slider with preload spring is inserted into the free space so that the spring pretensioning is oriented in the direction of the contact lug of the overvoltage protection unit. The slider is preferentially of wedge shape and/or sections of the brackets form an inclined surface in order to generate a force component on the parallel ends of the brackets when the slider moves such that they move away from the contact lug laterally.
Reference is made to DE 10 2007 042 991 B4 with respect to the design details of the slider and bracket, the disclosure of which is declared as being subject matter of the present teaching.
In accordance with the invention, the ends of at least one of the brackets oriented toward the contact lug form a limit stop for a visual indicator which is pivotable about an axis, wherein the pivoting motion is then enabled when the ends of the parallel-extending brackets are moved away from the contact lug laterally with the help of the slider.
In this embodiment of the invention, the position of the above-cited axis can be perpendicular to the path of movement taken by the slider, whereby expanded design options result for the arrangement of the visual indicator and, ultimately, the path traveled by the slider is uncoupled and separate from the movement or pivoting path of the visual indicator.
In one embodiment of the invention, the pivotable visual indicator comprises a pawl projection as well as a signaling projection, wherein the signaling projection gives way to a display area with color coding. The display area can hereby have a curved surface in order to maintain approximately the same distance relative to a display window depending on the pivot position.
During unhindered operation of the respective overvoltage protection unit in the respective overvoltage protection device, the pawl projection butts against the limit stop of the at least one bracket; i.e. the bracket blocks the movement of the pawl along with the pivotable visual indicator.
In one preferential embodiment of the invention, the above-cited limit stop can be formed as an integral or integrally molded projection relative to the corresponding end of the bracket. Since the brackets used for the disconnection apparatus are preferentially a punched/bent sheet metal part, the desired design to the projection can be readily realized in the punching process without technical complexity.
The pivotable visual indicator is pretensioned by a spring element, particularly one designed as a spring rod, such that when the pawl projection releases, the spring element moves the pivotable visual indicator into a predetermined pivoted position such that the e.g. “red” signal code of the visual indicator is brought into the area of the cited display window, signaling the interruption/disconnection process.
The preload spring element for the pivotable visual indicator also holds the latter in the respective position after disconnection has been effected; i.e. the red color code also remains in the display window upon mechanical manipulations such as rotation, vibration, etc.
The invention furthermore provides a supporting body for the overvoltage protection device which can be realized as a plug-in component, said supporting body accommodating a remote signaling contact slider in a bottom section.
The displacement path of the remote signaling contact slider is blocked or enabled by a lateral projection of the disconnection slider depending on its position. The remote signaling contact slider is hereby spring loaded, whereby the spring force vector exhibits no component of force toward the parallel ends of the disconnection apparatus brackets for lateral motion away from the contact lug.
Structurally, the supporting body has lateral guide surfaces comprising latching projections or engagement recesses for fixing the housing with the display window. In conjunction hereto, the housing has complementary engagement recesses or latching projections on its corresponding side surfaces.
In the invention as configured, a cavity for receiving an end of the preload spring is positioned in the longitudinal direction of the movable slider for the disconnection apparatus such that the spring is securely held. The complementary end of the spring can be guided by a rivet concurrently serving to connect a section of the metallic bracket to an external connecting part. A spot welding is equally possible.
As mentioned above, the ends of the bracket extending in parallel can be positionally fixed by a solder or a thermal adhesive, although are designed to separate in the disconnection process supported by a mechanical pretensioning.
The overvoltage protection unit, particularly a varistor, incorporated into the overvoltage protection device can be connected to the supporting body by a screw connection in order to prevent external forces from acting on the electrically relevant contact points. This screw connection also reduces external forces on the electrical connecting points including the thermal disconnection point, e.g. occurring in transport or other forces such as vibrations or the like.
The cited functional separation of the visual indicator and the actual disconnection apparatus with slider further provides the advantage of the disconnection process not being hindered by any possible blockage of the visual indicator movement.
The structural separation of the disconnection apparatus, the remote signaling contact control and the visual indicator can moreover effect a completely individual dimensioning of the spring preload force required in each case.
In the perspective side view according to
The connection element forming the disconnection apparatus consists of a pair of parallel-extending, current-dividing metallic brackets 1, 1′, their ends directed toward a contact lug 14 and receiving the respective contact lug 14 between them. A solder 3 or a thermally soluble adhesive or other such means secures the closed position between the connection elements and the contact lug 14 in the area of the parallel extending ends of the bracket 1.
As is evident from
The slider 4 has a wedge shape. Additionally or alternatively, corresponding sections of the brackets 1, 1′ forming an inclined surface are realized in order to create a force component on the parallel extending ends of the brackets 1, 1′ upon movement of the slider so that they will move away from the contact lug 14 laterally.
Reference numeral 9 in
The
Guide surfaces 25, which are a lateral component of the supporting body 11, comprise a latching projection in the example shown which forms a connection with a complementary engagement recess of the housing 6 and thus fixes the housing 6 to the supporting body 11 (see
The depiction of
The “separation-malfunction” operating condition can be comprehended on the basis of the
Similarly, the movement of the slider 4 upward in the figurative representation also moves the projection 24 of the slider 4 away from the remote signaling contact slider 16 so that the slider 16 can move to the right, left side of the
As a detail depiction of the position of the slider 4 upon disconnection,
The tooth height to the cog-like ends of the slider 4 is hereby also configured commensurate to the relevant height dimension of the contact lug 14.
The
Should the slider 4 move upward in the figurative representation, the remote signaling contact slider 16 can move to the right in the left part of the
The above comments on
In summary, the ends of at least one of the brackets 1, 1′ facing the contact lug 14 form a limit stop for the visual indicator 17 able to pivot about axis 10. The pivoting motion is then enabled when the parallel extending ends of the brackets 1, 1′ move laterally to the contact lug 14 by means of the slider 4.
The pivotable visual indicator 17 comprises the depicted pawl projection 18 as well as a signaling projection 19 which gives way to the display area 20 having the appropriate color coding.
The pawl projection 18 butts against the limit stop of the at least one bracket 1, 1′ in normal operation. The limit stop can be configured as for example in
The pivotable visual indicator 17 is held at a pretensioning by a spring rod 8.
The supporting body 11 depicted in the figures comprises the remote signaling contact slider 16 in its bottom section 23, whereby the displacement path is blocked or enabled by the lateral projection 24 of the slider 4 depending on the position of the slider 4.
The remote signaling contact slider 16 is likewise pretensioned, whereby the spring 26 is inserted into the slider hereto and braced against a corresponding bottom section 23 area of the supporting body 11. However, the spring preload exerts no force toward the parallel ends of the brackets 1, 1′ for lateral motion away from the contact lug 14. The disconnection point is thus not thereby subjected to unnecessary constant mechanical load or forces.
The cavity in slider 4 for receiving the preload spring 2 of the slider is recognizable in the left part of the
Number | Date | Country | Kind |
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10 2013 002 302 | Feb 2013 | DE | national |
10 2013 006 052 | Apr 2013 | DE | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/EP2014/051751 | 1/30/2014 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2014/122056 | 8/14/2014 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
3761856 | Mantelet | Sep 1973 | A |
6922131 | Walsh | Jul 2005 | B2 |
7477503 | Aszmus | Jan 2009 | B2 |
7684166 | Donati | Mar 2010 | B2 |
7839257 | Cernicka | Nov 2010 | B2 |
8526159 | Ludewig | Sep 2013 | B2 |
8836464 | Wang | Sep 2014 | B2 |
20110222199 | Ludewig | Sep 2011 | A1 |
Number | Date | Country |
---|---|---|
1 515 019 | Jun 1969 | DE |
2 220 264 | Nov 1972 | DE |
295 19 313 | Jan 1996 | DE |
102007006617 | Sep 2008 | DE |
10 2007 042 991 | Dec 2008 | DE |
0 905 839 | Mar 1999 | EP |
0 987 803 | Mar 2000 | EP |
Entry |
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International Search Report and Written Opinion for International Application No. PCT/EP2014/051751, dated Apr. 23, 2014, 10 pages. [no English translation available]. |
Number | Date | Country | |
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20160035523 A1 | Feb 2016 | US |