EP2382647B1

EP2382647B1 - Electric switch with melting member

Info

Publication number: EP2382647B1
Application number: EP09807514.6A
Authority: EP
Inventors: Anton Semrov; Peter Benko
Original assignee: ETI Elektroelement dd
Current assignee: ETI Elektroelement dd
Priority date: 2008-12-29
Filing date: 2009-12-16
Publication date: 2014-05-14
Anticipated expiration: 2029-12-16
Also published as: WO2010077209A1; SI22944A; EP2382647A1; SI22944B

Description

Invention belongs to the field of electricity, namely to basic electric elements, in particular to details of switching devices comprising built-in fuses and means for preventing arc.
The purpose of the invention is to conceive a protective electric switch with a melting member, which will be without amending its overall shape and dimensions adapted for mounting on commonly used bearing ledges of distribution panels in relevant electric circuits, and which should be able to receive a standardized essentially cylindrically shaped and with two silver-plated electrically conductive contact sections on both opposite ends furnished melting member, wherein a reliable contact between each of within the casing disposable contact members and each corresponding surface of the electrically conductive contact section of the melting member should be assured, and wherein each excessive scrubbing of said contact sections during insertion or removal of the melting member should be eliminated together with a preventing arc at least during a regular use of such switch.
Electric switch as described in SI 20131A consists of a casing, in which a bearing member of a melting member is mounted pivotally around its pivot axis. The melting member, which is placed on said bearing member, may then be pivoted around said pivot axis either towards the interior of said casing, where it is put in contact with corresponding electric contact members, or towards the exterior of the casing in such position that replacing of the melting member with a supplemental one is allowed. The shape and dimensions of such casing correspond to usual ones, which enables mounting thereof onto standardized ledges, which are available in distribution panels of electric circuits. Moreover, two locations are foreseen on the casing, in which electric supplying wires are attached to the switch in order to connect the connecting members within the casing into each appropriate electric circuit, into which in such a manner also the melting member is included. Each of these contact members cooperating with the melting member as long as available within the casing, consists of electric conductive metal plate, which is bent into essentially semi-circular hook, so that the overall shape thereof essentially corresponds to the Greek letter Ω (omega), so that a cylindrical electric conductive contact section, which is available on each end portion of the melting member, is then inserted between each pair of arms of each contact member. Each of said contact members usually consists of copper and is preferably plated with silver, wherein said copper is relatively plastic and is therefore difficult to assure a desired elasticity for the purposes of retaining the melting member in place by simultaneously maintaining a perfect electric contact between the surface of the contact member and the surface of the melting member. Of that reason, a steel spring may be foreseen on the outer surface of each contact member, which is sufficiently resilient to support maintaining the shape and resiliency of each contact member. However, manufacturing such contact members including also assembling thereof together with corresponding springs is quite difficult and involves essential expenses. Moreover, by pivoting the bearing member together with the melting member placed thereon towards the contact members located within the casing, the melting member with its surfaces quite slowly approaches to the arms of contact members, by which an electric discharging arc may easily occur, and by which also the wearing of surfaces of the contact members is essential.
A further electric switch with melting member is disclosed in FR 1 426 885 , which comprises a casing consisting of an electric insulating material and being furnished with two connectors, which are each per se adapted for integration of such switch into each disposable electric circuit. Said casing is moreover furnished with a bearing member, which consists of an electrically conductive material and is adapted to receive an essentially cylindrically shaped melting member, which is furnished with two cylindrical surface contact sections at its ends. Moreover, two electric contact members are available within said casing, which are adapted to interact with electrically conductive contact sections i.e. cylindrical surfaces of the melting member, and each of them is electrically connected with each corresponding connector on the casing. Each of said contact members, which are adapted to interact with cylindrically shaped electrically conductive contact sections of said melting member, comprises a rigid contact member and a resilient contact member. Each of said rigid contact members is electrically interconnected with each corresponding connector on the casing, and is moreover located just below a deflecting inclination, which consists of an electric insulation material and protrudes over said rigid contact member in a direction towards each corresponding resilient contact member. Just in order to assure each desired electric conductivity and also a sufficient resiliency for the purposes of functioning of each resilient contact members as such, according to available knowledge in this particular technical field, both rigid and resilient contact members arc supposed to consist of copper or aluminium or appropriate alloys on the basis of copper or alluminium. On such a basis, each cylindrical end contact sestion of each melting member may actually be inserted between each pair of rigid contact member and resilient contact member, and is upon that firmly held in its position, so that electric conductivity between each contact member and the cylindrical electric conductive contact section of the melting member is assured. Moreover, the melting member may also be removed, when desired. In order to assure said firmly positioning of the melting member, the tension between each resilient member and the melding member and the opposite rigid contact member must be sufficiently high. Whenever such melting member is inserted between each two disposable pairs of rigid and resilient contact members, the pressure between the surface area of the melting member and the contact member is still higher than the pressure of maintaining said contact member in position in its inserted state.
As also known to those skilled in the art, melting members are commonly used and each manufacturer must permanently bear in mind the cost aspects. Both electric conductive cylindrical contact sections on the opposite ends of said melting member consist of an electrically conductive metallic material, and are moreover furnished with a thin surface coating consisting of silver. Such coating should assure excellent electric conductivity and among other also prevents the surface against corrosion, in particular where local electric arcs might appear. The price of silver is essentially higher than the price of other commonly used electric conductive metallic materials, and the tendency of each manufacturer is to provide the silver coating as thin as possible. Despite to the fact that the thickness of said surface coating is sufficient for the purposes of assuring electric conductivity and corrosion resistance, by inserting such melting member between said pairs of rigid and resilient contact members according to FR 1 426 885 , said surface is unavoidable scrubbed in such extend that upon inserting problems with both electric conductivity and corrosion resistance may appear in the most of cases.
A still further fuse arrangement is disclosed in WO 2004/036610 A1 . The majority of features thereof correspond to those as mentioned in connection with FR 1 426 885 . According to WO 2004/036610 A1 , each rigid contact member may consist of copper and may also be coated with silver, when desired. Each resilient contact member should consist of spring steel. When using such combination of surfaces of said contact member together with a sliver-plated surface of the melting member, the friction between the surfaces is such that during insertion of the melting member, said melting member is still moved translatory with regard to both neighboring contact members. Consequently, the undesired scrubbing of the surface coating from the melting member cannot be avoided without enabling rotation of the melting member by means of rolling along one and smoothly sliding along the other contact member, when observing just a pair of each rigid and resilient contact members.
The present invention refers to an electric switch with melting member, which comprises a casing consisting of an electric insulating material and being furnished with two connectors adapted for integration of such switch into each disposable electric circuit, and which is moreover adapted to receive of electrically conductive material consisting bearing member for an essentially cylindrically shaped melting member comprising cylindrical surface contact sections at its ends. Two electric contact members are available within said casing, which are adapted to interact with electrically conductive contact sections of the melting member and each of them is electrically connected with each corresponding connector on the casing.
Each contact member, which is adapted to interact with electrically conductive sections of the melting member, comprises a rigid contact member and a resilient contact member, wherein each of said rigid contact members is electrically interconnected with each corresponding connector on the casing and is moreover located just below a deflecting inclination, which is preferably an integral part of the casing and consists of an electric insulation material and protrudes over said rigid contact member in a direction towards each corresponding resilient contact member.
Each available rigid contact member consists merely of copper or of an alloy on the basis of copper, and is moreover at least on the surface, which is faced towards each corresponding resilient contact member, furnished with an electric conductive surface coating, which preferably consists of silver.
According to the invention, each resilient contact member preferably consists of steel, especially of spring steel, and is at least on the surface, which is faced towards each corresponding rigid contact member, furnished with an anticorrosion coating, which preferably consists of nickel or of alloy on the basis of nickel.
The bearing member of the melting member is guided within the casing by means of guides, which are either linear or slightly curved and extend towards the contact members.
A further possible bearing member of the melting member comprises at least two chambers, which are adapted to receive a melting member, namely an active chamber, which is faced towards the interior of the casing of the switch into which each the melting member is inserted, which is intended for establishing appropriate electric circuit, and moreover at least one passive chamber, which is arranged adjacent to said active chamber in a direction outwardly from the casing and is adapted to receive at least one supplemental melting member.
Now the invention will be described in more detail on the basis of an embodiment, which is presented in the attached drawing, wherein

Fig. 1: is a schematically shown longitudinal cross-section of the switch according to the invention;
Fig. 2: is a switch according to Fig. 1 upon removal of covering member of the casing;
Fig. 3: is a cross-section along the plane A - A extending throughout the casing according to Fig. 2;
Fig. 4: is a cross-section along the plane B - B extending throughout the casing according to Fig. 2, observed in the state during insertion or removal of the melting member;
Fig. 5: is a cross-section along the plane B - B extending throughout the casing according to Fig. 2, observed in the state just before introducing the melting member into an electric circuit;
Fig. 6: is a cross-section along the plane B - B extending throughout the casing according to Fig. 2, observed in the state after introducing the melting member into an electric circuit; and
Fig. 7: is a detail C according to Fig. 5.

Electric switch according to the invention comprising a casing 1 consisting of an electric insulating material, which is adapted to receive a bearing member 2 of a melting member 3, wherein said bearing member 2 also consists of an electric insulating material.
Said melting member 3 is a typical cylindrically shaped fuse, which is known to those skilled in the art and generally consists of an electric insulating material, and which is on its both opposite ends furnished with cylindrically shaped electrical conductive surface contact sections 31, 32, which are electrically interconnected via a not-shown protective melting member, which is preferably placed within said member 3.
The bearing member 2 of the casing 1 is preferably an uniform part, which is allowed to be removed from the casing 1 and is guided within said casing 1 by means of guides 20, which are arranged on lateral surfaces of the casing 1 as well as on the bearing member 2, which may either extend in a straight or slightly curved direction, which is e.g. shown in Figs. 1 and 2. In this particular embodiment, two chambers 21, 22 are foreseen on said bearing member 2 adjacent to each other, namely a passive chamber 21 as well as an active chamber 22. Each time actively used melting member 3 is placed within said active chamber 22, while the passive chamber 21 is e.g. foreseen for storage of a substitute melting member 3. When the melting member 3 is appropriately inserted within said active chamber 22 of the bearing member 2, it is appropriately positioned on the bearing member 2 and ready for insertion into the casing 1. Besides, when placed within said active chamber 22 of the bearing member 2, said melting member 3 may be freely rotated around its longitudinal axis.
When observed from outside, said casing 1 essentially corresponds to casings of known switches, at least when taking into account the shape and dimensions thereof, and is firmly attachable to each (not shown) bearing ledge of a distributing panel of each electric circuit. Moreover, two connectors 103, 104 are available on said casing 1, which are adapted for interconnection of such switch with each disposable electric conduits of appropriate electric circuit, into which such switch is to be integrated. Said connectors 103, 104 are each per se electrically connected to each appropriate electric contact member 11, 12, which are arranged within the casing 1 in such area and in such position that interaction thereof with each corresponding electrically conductive contact section 31, 32 of the melting member 3 (Figs 4 to 7) is enabled. Each of said contact members 11, 12 consists of an appropriately rigid contact member 112, 122, which is fixed within said casing 1, as well as of a resilient contact member 111, 121. Each rigid contact member 112, 122 is electrically interconnected with each corresponding connector 103, 104 on the casing 1.
A deflecting inclination 13 consisting thereby of an electrically insulating material like the casing 1 as such is foreseen within the casing 1 above each rigid contact member 112, 122 and protrudes beyond each corresponding rigid member 112, 122 (Fig. 7) in a direction towards each belonging resilient contact member 111, 121.
Each rigid contact member 112, 122 preferably consists of a copper plate and is preferably furnished with a surface, which is coated with silver. On the other hand, each resilient contact member 111, 121 preferably consisting of a steel plate, which is protected against corrosion preferably by means of a coating on the basis of nickel. As known to those skilled in the art, also the electrically conductive surface contact sections 31, 32 of the melting member 3 are usually furnished with a coating on the basis of silver.
As soon as the bearing member 2 is moved outwardly from the casing 1, appropriate melting member 3 is allowed to be iliserted into the active chamber 22 of the bearing member 2, upon which the bearing member 2 is inserted back to the casing 1 in the area of guides 20 (Fig. 4). As soon as the bearing member 2 together with the melting member 3 is moved sufficiently deep into said casing 1, so that the electrically conductive contact sections 31, 32 thereof are located adjacent to said contact members 11, 12, each of said contact sections 31, 32 initially abuts the deflecting inclination 13 (Fig. 5), but the electric contact between the surface of said contact section 31, 32 and the rigid contact member 112, 122, which is electrically interconnected with connectors 103, 104, is not yet established in such a state. During a further movement of the bearing member 2 together with the melting member 3 in a direction of inserting the melting member 3, the last is initially by means of electrically conductive surface contact sections 31, 32 rested to the resilient contact member 111, 121, which are then deflected in such extent that said contact sections 31, 32 of the melting member 3 are moved closely to the deflecting inclination 13 between each corresponding pair of resilient contact member 111, 121 and rigid contact member 112, 122 in order to be maintained in such a state, and are upon that via rigid contact members 112, 122 integrated within the electric circuit. Due to the fact that said contact sections 31, 32 of the melting member 3 are held at a sufficient distance apart from the previously mentioned voltage-exposed rigid contact members 112, 122 up to the moment in which these are actually pressed towards said rigid contact members 112, 122 by means of resilient contact members 111, 121, at least in conditions of regular use of such switch, formation of the electric discharging arc is a priori excluded.
Moreover, since the coefficient of friction between each silver-plated surface of each electrically conductive contact section 31, 32 of the melting member 3 and each corresponding silver-plated surface of the rigid contact member 112, 122 is greater than the friction coefficient between each nickel-plated surface of each resilient contact member 111, 121 and the silver-plated surface of each corresponding contact section 31, 32 of the melting member 3, during insertion of the melting member 3 among each pair of contact members 111, 121; 112, 122 is not sliding along both rigid contact members 112, 122 but is rolled by turning thereof around its longitudinal axis in one direction by inserting and in opposite direction by removing thereof. Consequently, such effect at the one hand results in reduction of forces, which are required by insertion or removal of the melting member 3, and on the other hand simultaneously also to elimination of scrubbing and wear of each disposable electrically conductive surface coatings on said rigid contact members 112, 122 and also on the contact sections 31, 32 of the melting member 3 as such.

Claims

Electric switch with melting member (3), comprising a casing (1), which consists of an electric insulating material and is furnished with two connectors (103, 104), which are adapted for integration of such switch into each disposable electric circuit, and which is moreover adapted to receive of electrically conductive material consisting bearing member (2) for an essentially cylindrically shaped melting member (3) comprising cylindrical surface contact sections (31, 32) at its ends, wherein two electric contact members (11, 12) are available within said casing (1), which are adapted to interact with electrically conductive contact sections (31, 32) of the melting member (3) and each of them is electrically connected with each corresponding connector (103, 104) on the casing (1), wherein each contact member (11, 12), which is adapted to interact with electrically conductive contact sections (31, 32) of the melting member (3), comprises a rigid contact member (112, 122) and a resilient contact member (111, 121), and wherein each of said rigid contact members (112, 122) is electrically interconnected with each corresponding connector (103, 104) on the casing (1) and located just below a deflecting inclination (13), which consists of an electric insulation material and protrudes over said rigid contact member (112, 122) in a direction towards each corresponding resilient contact member (111, 121), each available rigid contact member (112, 122) consists merely of copper or of an alloy on the basis of copper and is furnished with a silver surface coating at least on the surface, which is faced towards each corresponding resilient contact member (111, 121), characterized in that each resilient contact member (111, 121) consists of steel, especially of spring steel, which is furnished with an anti-corrosion coating at least on the surface, which is faced towards each corresponding rigid contact member (112, 122), and said surface coating on each disposable resilient contact member (111, 121) consists of nickel or of alloy on the basis of nickel.
Electric switch according to Claim 1, characterized in that the bearing member (2) of the melting member (3) is guided within the casing (1) by means of guides, which are either linear or slightly curved and extend towards the contact members (11, 12).