Snap-action switch

Abstract

The invention relates to a snap-action switch (100) comprising a housing (1), an actuation plunger (2) with two switch positions and with at least one contact bridge (31, 32) for electrically connecting at least one first contact pair (23, 24) in a switch position and with snap-action springs (8, 9) which are supported substantially symmetrically and in a pretensioned manner on an actuation element (3) and the actuation plunger (2) and which have pitch lines that can be shifted by the actuation element (3) in such a way that the actuation plunger (2) can be snapped from a first switch position, in which the actuation plunger (2) is substantially in a resting position, into a second switch position, in which the actuation plunger (2) is substantially in the actuation position, wherein the snap-action switch (100) also has a forced-opening assembly with which a switching at least from the first into the second switch position is imposed on the actuation element (3) when a forced-opening force is exceeded, wherein the at least one contact bridge (31, 32) has two respective contact points (17, 18, 19, 20) at one end and the other end for the electrically parallel contacting of the first contact pair (23, 24), wherein each of the contact points (17, 18, 19, 20) is designed in such a way as to entirely switch an electrical rated power of the snap-action switch (100).

Description

[0001] Snap switch

[0002] The present invention relates to a snap switch according to the preamble of claim 1.

[0003] Snap-action switches are generally known from the prior art and typically comprise a housing and a contact bridge having two switching positions that can be switched via an actuating plunger for electrically connecting fixed contacts, in particular at least one first contact pair in the first switching position and at least one second contact pair in the second switching position. Two snap-action springs are supported essentially symmetrically and under pretension on an actuating element and the actuating plunger, the lines of action of which are displaceable by the actuating element such that the actuating plunger can be snapped from the first switching position, in which the actuating plunger is essentially in the rest position, to the second switching position, in which the actuating plunger is essentially in the actuated position.

[0004] Snap-action switches have in common that they operate with a bistable snap-action spring arrangement, which results in a rapid switching movement when a certain switching point is exceeded. This rapid switching movement is intended to minimize arcing and thus damage to the contact elements. To provide this function, it is irrelevant whether the spring arms are formed integrally with the contact bridge or designed as separate components.

[0005] A snap switch known from the prior art is shown in Figure 9.

[0006] The snap-action switch shown has a housing 1 with a rectangular cross-section, which serves to accommodate the individual components of the snap-action switch. An actuating plunger 2 is arranged centrally in the housing 1. Inside the housing 1, the actuating plunger 2 has a stop step which, when the actuating plunger 2 is in its rest position, rests against the inside of a wall of the housing 1. The actuating plunger 2 is pressed upwards into its rest position by a compression spring 4, so that the stop step 3 comes into secure contact. The actuating plunger 2 is guided in a sleeve-like receptacle in the area of ​​the compression spring 4 and, at an end opposite the compression spring 4, in a recess in the housing 1.

[0007] Approximately at the level of half of a longitudinal extension of the actuating plunger 2 located within the housing 1, the plunger has two diametrically opposed, i.e., in the present embodiment, mirror-image, receiving notches 7, each of which is designed to support a V-shaped snap spring 8, 9 on one side. A contact carrier 10 is held under prestress on the actuating plunger 2 by means of the snap springs 8, 9.

[0008] The other end of the snap springs 8, 9 is each received in a receiving notch 11, 12 of an insulating spacer 13, 14. The spacers 13, 14 hold an upper contact arm 15 and a lower contact arm 16 parallel to each other and spaced apart from each other. The contact arms 15, 16 are approximately O-shaped when viewed from above. They are held in place by the snap springs 8, 9 being arranged under pretension between the actuating plunger 2 and the spacers 13, 14, so that the spacers 13, 14 are pressed against the contact arms 15, 16, thus securing them in their position.

[0009] The contact arms 15, 16 have contact areas 17, 18, 19, 20 arranged at the ends, wherein the contact areas 17, 18, 19, 20 arranged on the contact arms 15, 16 are each assigned opposite fixed contacts 21, 22, 23, 24, so that in each case one contact arm 15, 16 in the actuating position and the other contact arm 16, 15 in the rest position of the snap switch contacts the fixed contacts 21, 22, 23, 24 assigned to it and connects them to one another in an electrically conductive manner.

[0010] A first fixed contact 21 is assigned to a first contact area 17, and a second fixed contact 22 is assigned to a second contact area 18. The first fixed contact 21 and the second fixed contact 22 are thus electrically connected to one another by the upper contact bridge 15 and form a first contact pair. Similarly, a third fixed contact 23 is assigned to a third contact area 19, and a fourth fixed contact 24 is assigned to a fourth contact area 20, so that the third fixed contact 23 and the fourth fixed contact 24 are electrically connected to one another by the lower contact bridge 16 and form a second contact pair.

[0011] Since thermal overload of the contact points can lead to unwanted welding of the contact areas of the contact arms to the contacts of the contact pairs, i.e., the fixed contacts, in such snap-action switches, lever elements for positive opening are provided in some applications. Annex K of the DIN EN 60947-5-1 standard specifies such a rigid, positive opening mechanism in addition to the snap-action spring mechanism for standard snap-action switches. This ensures that, for safety reasons, the normally closed contact position is reliably opened when the actuating element of the snap-action switch is actuated. This positive opening mechanism is capable of opening contact points welded together by excess current by applying appropriate force.These lever elements are usually pivotable over the switching plunger and can be placed at one end against the contact carrier or the contact arms. When sufficient force is applied to the switching plunger, they force the contact areas away from the contact pairs, thus forcing the switching position open. To configure one of the switching positions as the rest position, an additional spring element can be integrated into the snap-action switch, as shown in the example in Figure 9, so that the position of the contact carrier in the rest position is stabilized by the force of the spring element.

[0012] The familiar snap-action switches are already very reliable and can be used for safety-critical applications. However, it is considered a disadvantage that they can fail electrically due to various effects, i.e., the contact arms fail to establish a conductive connection between the fixed contacts or only do so inadequately. Reasons for such failure can include excessive contact resistance due to deposits of dirt or burn-off on the contacts, breakage of the snap springs or the contact bridge due to mechanical and / or thermal stress.

[0013] It is therefore the object of the present invention to improve a known snap-action switch. This object is achieved by a snap-action switch having the features of patent claim 1. Advantageous further developments are the subject of dependent claims and the following description.

[0014] A snap-action switch according to the invention comprises a housing, an actuating plunger having two switching positions with at least one contact bridge for electrically connecting at least a first contact pair in a switching position, and snap-action springs supported substantially symmetrically under prestress on an actuating element and the actuating plunger, the lines of action of which are displaceable by the actuating element such that the actuating plunger can be snapped from a first switching position, in which the actuating plunger is substantially in the rest position, to a second switching position, in which the actuating plunger is substantially in the actuated position, wherein the snap-action switch further comprises a positive opening arrangement, by means of which a switching at least from the first to the second switching position is forced upon exceeding a positive opening force on the actuating element,wherein the at least one contact bridge has at least two contact points at one end and at the other end for electrically contacting the first contact pair in parallel, wherein each of the contact points is designed to completely switch an electrical rated power of the snap switch.

[0015] The inventive design creates electrical and mechanical redundancy, so that even in the event of a failure of up to two contact points, the snap-action switch remains available. The contact bridge can be implemented using electrically and mechanically parallel electrical conductors. In this way, with two parallel electrical conductors, for example, the electrical or mechanical failure of one of the conductors—in this case, the two contact points associated with that conductor—can be compensated for.

[0016] The snap-action switch can be designed as a normally closed or normally open contact, with the rest position of the actuating plunger defining whether it is a normally closed contact, i.e., an open contact, or a normally open contact, i.e., a make contact. In an advantageous embodiment, the snap-action switch has two contact bridges for electrically connecting at least the first contact pair and at least one second contact pair. The contact points of the second contact bridge are also designed to fully switch the electrical rating of the snap-action switch.

[0017] Two contact bridges can be used to create a double opener or a double closer.

[0018] If the snap switch is designed in such a way that the first contact pair is connected in the first switching position and the second contact pair is connected in the second switching position, the snap switch is implemented as an opener or a closer, depending on which fixed contacts are contacted from the outside.

[0019] In an advantageous embodiment, the snap-action switch comprises a housing, an actuating plunger having two switching positions with at least two contact bridges for electrically connecting at least a first contact pair in the first switching position and at least a second contact pair in the second switching position, and with snap-action springs supported substantially symmetrically under pretension on an actuating element and the actuating plunger, the lines of action of which are displaceable by the actuating element in such a way that the actuating plunger can be snapped from the first switching position, in which the actuating plunger is substantially in the rest position, into the second switching position, in which the actuating plunger is substantially in the actuated position, wherein the snap-action switch further comprises a positive opening arrangement,by means of which switching from the first to the second switching position is forced upon exceeding a positive opening force on the actuating element, is characterized in that the at least two contact bridges each have at least two contact points at one end and the other end for electrically parallel contacting of the first contact pair in the first switching position and the second contact pair in the second switching position, wherein each of the contact points is designed to completely switch an electrical rated power of the snap-action switch. A design of the contact bridges with at least two contact points each has the advantage that electrically parallel contacting of the contact pairs can be achieved in this way. This means that the failure of one switching point per contact point can be compensated for per switching bridge, which meansThis means that a contact point at either end of the contact bridge can fail, for example, due to contamination, burnout, or a mechanical defect, while the functionality of the snap-action switch is still maintained. This creates additional redundancy and increases switching reliability. The availability of the snap-action switch increases.

[0020] In a design with two contact points per bridge end, the following contacting options are possible with cross-contacting of the contact bridge parts, i.e., if the contact bridge is designed so that all contact points are electrically connected to one another: Ideally, both contact points on both sides make contact. In the event of any failure of one of the contact points, either on the input side and / or the output side, a situation exists in which at least one contact point is functional.

[0021] The term "contact point" is used here only to distinguish between the different positions of the contacts. Contact points are therefore not necessarily point-shaped, but can also be linear or flat.

[0022] The term "contact pair" is also used merely for differentiation. Contact pairs are always the contact points of the associated fixed contacts located at opposite ends of a switching bridge. These comprise at least two contact points, i.e., a pair, but can also comprise several contact points. Preferably, however, the fixed contacts at both ends of the contact bridge comprise an identical number of contact points.

[0023] In an advantageous development of the snap-action switch, the contact bridges are each formed as a single piece. "Single piece" in this context means that the contact bridges are made entirely of the same material, which provides both the energy transfer and the static load-bearing properties. In contrast to the prior art, the contact bridges are thus characterized by a simple structure. The material of the contact bridges is therefore preferably both conductive and load-bearing.

[0024] A metal or metal alloy with springy properties is particularly suitable for the design of the contact bridge. Spring steel, for example, can be used, although bronze, brass, nickel silver or copper alloys are preferred due to their higher conductivity. A copper-beryllium alloy is particularly preferred because it combines particularly good electrical and thermal conductivity with mechanical properties. Copper-nickel-silicon alloys can also be used due to the good electrical and thermal conductivity combined with good mechanical properties that can be achieved with these alloys. This type of design ensures that the contact bridge is mechanically stable despite its small material cross-section and is sufficiently dimensioned for the currents to be switched.

[0025] In a preferred embodiment, the contact bridges are designed in the form of a double H-bridge, each with an H-bridge with two bridge legs on either side of the actuating plunger and at least one transverse web.

[0026] The term H-bridge refers to the design of the contact bridge in the shape of an "H". This design provides two parallel contact paths for contacting the contact pairs of the fixed contacts, whereby at the same time a cross contact can be made from one leg of the H-bridge to the other leg of the H-bridge via the crossbar.

[0027] The H-bridge design also offers the advantage that the individual legs of the H-bridge can be flexibly configured in the actuation direction, allowing height compensation of the individual contact points at one end of the bridge. For example, the H-bridge can be used to compensate for a height difference between the contact points at one end of the H-bridge caused by a particle. The contact bridge can also be configured such that on either side of the actuation plunger, one bridge leg is leading and the other bridge leg is lagging. With such a design, a contact bridge can be realized in which the contact point located on the leading bridge leg is primarily exposed to switching arcs and the associated burn-off.

[0028] In this context, "leading" means that the leading leg of the contact bridge, or the contact point located on the leading leg, comes into contact with the fixed contacts first in the closing direction of the contact bridge, establishing an electrically conductive connection. The lagging contact point only contacts the fixed contact once a conductive connection has already been established via the leading leg.

[0029] Conversely, when opening, this means that the lagging leg of the contact bridge first breaks the electrical connection, followed by the leading leg. This ensures that a switching arc is created exclusively at the leading contact point, and only the leading contact point is prone to welding to the fixed contact, as this switches higher currents than the lagging contact.

[0030] In a preferred embodiment, the material of the respective contact point can be adapted accordingly. In particular, the contact points on the leading legs can be designed to be more resistant to erosion. Suitable materials for the contact points of the leading leg include silver, gold, or silver or gold alloys.

[0031] Conversely, the trailing leg can have contact points made of a highly conductive but less resistant material, e.g. gold.

[0032] With mixed loads, the leading contact point switches the high currents and is loaded accordingly. The lagging contact point switches when the contact resistance of the leading contact point becomes too high at lower currents. The lagging contact can have a contact material more suitable for lower loads, as it does not switch high loads. In another embodiment, the contact bridges are designed to be spring-elastic. This allows manufacturing tolerances to be compensated and reliable contact to be achieved, for example, by height compensation for particles. Furthermore, a spring-elastic design of the contact bridges can assist in opening the snap-action switch. The metals and metal alloys already mentioned above for the design of the contact bridge are particularly suitable materials.

[0033] Reliable contacting can also be achieved if the contact bridges are designed and the contact points are arranged in such a way, and relative to the contact pairs, that the contacts are self-cleaning.

[0034] Self-cleaning of the contacts can be achieved, for example, by designing the contact points and the contact pairs and arranging them relative to each other in such a way that a lateral movement is caused between the contact point and the contact pair, at least when the contacts are closed.

[0035] Such a lateral movement removes and removes deposits caused by burn-off, for example, during the lateral movement, thus always ensuring reliable contact.

[0036] If, for example, the contact bridge is made of a spring-elastic material, then when an electrical connection already exists, ie when the contact points are already in contact with the contact pairs, a further movement of the contact bridge in the closing direction can cause a lateral movement of the contact points and the contact pairs relative to each other, whereby deposits are rubbed off and simultaneously pushed away from the contacts.

[0037] In one embodiment, a reinforcement arrangement can be assigned to each of the at least two contact bridges in the opening direction. This reinforcement arrangement allows the contact bridges themselves to be dimensioned more weakly while still maintaining sufficient stability. Such a reinforcement arrangement can be particularly useful in the opening direction, since welds caused by thermal stress may have to be removed in this direction. At the same time, if a reinforcement arrangement is used exclusively in the opening direction, flexibility in the closing direction can be achieved on the one hand, while ensuring sufficient stability in the opening direction on the other.

[0038] Such a reinforcement arrangement can, for example, be arranged on the actuating plunger, in particular be formed integrally with the actuating plunger.

[0039] Alternatively, a multi-part design is also conceivable, in which the reinforcement arrangement is designed as a separate component.

[0040] By arranging the reinforcement arrangement, and in particular by forming the reinforcement arrangement in one piece with the actuating plunger, a particularly space-saving and, in particular, easily implemented realization can be achieved in terms of production technology.

[0041] The reinforcement arrangement can, for example, be designed as a molded portion extending from the actuating plunger in the direction of the contact bridge's extension, particularly in the form of reinforcement arms. Such molded portions can be implemented particularly easily during the manufacture of the actuating plunger, for example, by plastic injection molding, and can be produced to the required dimensions.

[0042] It is preferred if the projections support the bridge legs, at least in the uncontacted state, by at least 1 / 5, preferably at least 1 / 4, more preferably at least half, particularly preferably at least 3 / 4 in the area projecting beyond the actuating plunger. The larger the contact area of ​​the legs of the contact bridge on the projections, the greater the supporting effect in the opening direction, so that support of more than 3 / 4 can also be useful. The increased supporting effect is achieved by a larger contact surface reducing the overhang, i.e. the length by which the contact bridge projects beyond the projection. An opening force acting on the actuating plunger is thus transmitted to the contact bridge over a larger area, and at the same time the freely projecting length of the contact bridge is reduced. A force acting counter to the opening, e.g.By welding the contact point to the fixed contact, the lever arm is reduced, reducing the risk of the contact bridge bending. In a preferred embodiment, the projections are shaped to prestress the contact bridge. A preferred embodiment is therefore one in which the projections on the actuating plunger bend a contour of the contact bridge, so that it advantageously has a defined prestress.

[0043] Preloading the contact bridge offers various advantages. Manufacturing tolerances of the contact bridge can be compensated for without the need for rework, as the contact bridge is positioned in a defined position by the moldings. Furthermore, it is possible to apply a defined preload to the contact bridge, thus providing an immediate increase in force in the opening direction to open the contacts.

[0044] In this context, the contour of the bridge legs refers in particular to the course of the bridge legs in a side view.

[0045] The contact bridge can be designed, in particular, as a stamped and bent part. Stamped and bent parts can be manufactured cost-effectively and with high quality.

[0046] Alternatively, other manufacturing methods can also be used, especially for smaller quantities. For example, various cutting processes, such as waterjet or laser cutting, can be used, followed by a bending step.

[0047] In order to reliably transmit a prescribed opening force for positive opening of the rest position, the projections are dimensioned such that an opening force of at least 10 N, preferably 20 N, more preferably 30 N can be transmitted to the contact points of the bridge legs. In this way, it can be ensured that the snap-action switches according to the present application also comply with the standard DIN EN 60947-5-1. However, the projections also make it possible to transmit higher positive opening forces than the 20 N required by the standard, so that in particular a transmission of 30 N and more can be achieved. The actuating plunger can, for example, be designed in at least two parts such that the contact bridge can be inserted between two parts of the actuating plunger and thus fixed.

[0048] In an alternative design, the contact bridge is overmolded with the actuating plunger. This design has the advantage of being particularly cost-effective, reducing the number of components of the snap-action switch, and providing particularly good fastening of the contact bridge, as the contact bridge is fixed in the area of ​​the actuating plunger with a positive and non-positive fit.

[0049] All contacts, both on the contact bridge and the fixed contacts, can be cylindrical, flat, or spherical / oval (contact rivet). The contact surface of spherical contacts is point-shaped, cylindrical contacts are linear, and double-surface contacts are flat.

[0050] The self-cleaning of the switching points can be designed as a pushing or pulling action. Depending on the angle at which the contact points and the contact pairs meet, a pushing or pulling relative movement is performed between the contacts. Further details can be found in the exemplary embodiments described below.

[0051] Advantageous embodiments and variants of the invention emerge from the dependent claims and the following description. The features listed individually in the dependent claims can be combined with each other in any technically reasonable manner, as well as with the features explained in more detail in the following description, and represent other advantageous embodiments of the invention.

[0052] The present invention will be explained in detail below using exemplary embodiments with reference to the accompanying figures. They show:

[0053] Figure 1 shows a first embodiment of a snap-action switch according to the present application in a simplified representation, Figure 2 shows a schematic diagram of the actuating plunger with the first

[0054] Contact bridge and associated fixed contacts,

[0055] Figures 3a) to c) show a closing process of a contact bridge of the snap switch according to Figure 2,

[0056] Figures 4a) to c) show an opening process of the contact bridge from Figure 3,

[0057] Figures 5a) and 4b) show an alternative design of a contact bridge during closing (Figure 5a)) and opening (Figure 5b)),

[0058] Figure 6 shows a third embodiment of a contact bridge,

[0059] Figure 7 shows a fourth embodiment of a contact bridge,

[0060] Figures 8a) and 8b) show a contact bridge with a leading and a trailing bridge leg and

[0061] Figure 9 shows a snap switch according to the prior art

[0062] (already treated).

[0063] In the figures, unless otherwise stated, the same reference symbols designate the same or corresponding components with the same function.

[0064] Figure 1 shows a first embodiment of a snap switch 100 according to the present application.

[0065] The snap-action switch 100 is simplified in the illustration shown and shown with an open housing, so that the functionality of the components located in the snap-action switch 100 is more clearly visible. The essential function of the snap-action switch 100 is accomplished by an actuating plunger 2 having at least two switching positions, wherein the actuating plunger 2 can be switched by means of an actuating element 3 between a first switching position, as shown in Figure 1, and a second switching position, in which the actuating plunger 2 is in a position displaced relative to the first switching position in the direction of the actuating element 3.The switching element 3 is connected to the actuating plunger 2 via two snap springs 8, 9 supported in parallel on the switching element 3 and the actuating plunger 2, so that actuation of the actuating element 3 shifts the characteristics of the snap springs 8, 9 such that the actuating plunger 2 is snapped from the first switching position to the second switching position. In the present embodiment, the actuating element 3 is further actuated by a compression spring 4, so that the first switching position shown in Figure 1 is stabilized by the compression spring 4.

[0066] The snap-action switch 100 shown in Figure 1 further comprises a positive opening arrangement consisting of a first positive opening lever 5 and a second positive opening lever 6. The positive opening levers 5, 6 are supported at one end on a circumferential collar of the actuating plunger 2 and at the other end are slidably mounted in the housing of the snap-action switch 100. If a predetermined actuating force is applied via the actuating element 3, this comes into contact with the positive opening levers 5, 6 and, by tilting the positive opening levers 5, 6, effects an indirect mechanical coupling of the actuating element 3 via the positive opening levers 5, 6 to the actuating plunger 2, so that, in the event that a snap-action switchover of the actuating plunger 2 from the first switching position to the second switching position could not be effected, a mechanically forced switchover occurs.

[0067] As already explained with reference to the prior art, such a positive opening may be necessary if, for example, due to thermal stress, contacts of the snap-action switch 100 are welded together in a switching position (in this case the first switching position) and as a result the snap-action springs 8, 9 are not able to release the contacts and switch the switching position.

[0068] In the snap-action switch 100 shown in Figure 1, a first contact bridge 31 and a second contact bridge 32 are arranged on the actuating plunger 2. In the first switching position of the actuating plunger 2 shown in Figure 1, the first contact bridge 31 is not in contact with its associated fixed contacts 21, 22, and the second contact bridge 32 electrically connects a third fixed contact 23 and a fourth fixed contact 24. To contact the respective fixed contacts 21, 22, 23, 24, the contact bridges 31, 32 have contact points arranged on their ends, which reinforce the contact bridges and thus make them wear-resistant.

[0069] Figure 2 shows a schematic diagram of the actuating plunger 2 with the first contact bridge 31 and the fixed contacts 21, 22 assigned to it in the second switching position.

[0070] The following statements regarding the first contact bridge 31 also apply mutatis mutandis to the second contact bridge 32.

[0071] The illustration in Figure 2 is highly simplified and is essentially intended to explain the operating principle of the illustrated embodiments in more detail. The first contact bridge 31, now shown in detail, is held in a recess of the actuating plunger 2. In the illustrated embodiment, the first contact bridge 31 is designed as a so-called H-bridge, wherein the contact bridge 31 resembles the letter "H" in a top view and has two parallel bridge legs 311, 312, which are connected to one another by means of a crosspiece 313 (not visible in Figure 2). Reinforced contact points 314, 315, 316, 317 are arranged at the ends of the bridge legs 311, 312, which reinforce the contact bridge 31 and thus make it wear-resistant.In the present embodiment, the contact points 314-317 are designed as cylindrical shell-shaped reinforcing surfaces welded to the ends of the bridge legs 311, 312. The cylindrical shape extending transversely to the direction of extension of the bridge legs 311, 312 creates a linear contact surface between the fixed contacts 21, 22, which are flat in the present embodiment, and the contact points 314-317, over which electrical current flows.

[0072] In contrast to the prior art, the contact bridge 31 is not in the form of a contact carrier, i.e., in particular, it is solidified, but rather a concavely curved leaf spring which is supported in the opening direction, i.e., when an electrical contact closed between the contact points 314-317 and the fixed contacts 21, 22 is opened again, by a reinforcing arrangement in the form of reinforcing arms 25, 26 arranged on the actuating plunger 2. In the present exemplary embodiment, the reinforcing arms 25, 26 are formed as integral parts with the actuating plunger 2 and support the contact bridge 31 in the opening direction, as will be explained in more detail below in connection with Figure 3.

[0073] Figure 3 shows in the sub-figures 3a) to 3c) the arrangement from Figure 2 in a plan view from the front when closing the contact between the contact bridge 31 and the fixed contacts 21, 22.

[0074] Figure 3a) shows how the actuating plunger 2 moves from the first switching position, in which - as shown in Figure 1 - the second contact bridge 32 contacts the fixed contacts 23, 24, to the second switching position, in which contact is established between the first contact bridge 31 and the fixed contacts 21, 22. The direction of movement of the actuating plunger 2 is indicated by the arrow shown in Figure 3a). In the first partial figure, it can be clearly seen that the bridge legs 311, 312 extending on both sides of the actuating plunger 2 - in the present illustration, this is the forward-facing bridge leg 312 - rest against the reinforcement arrangement in the form of the reinforcement arms 25, 26.The first contact bridge 31 is shaped such that the bridge legs 311, 312 initially follow the contour of the reinforcing arms 25, 26 with a positive curvature and then bend with a negative curvature in the direction of the horizontally extending fixed contacts 21, 22.

[0075] Figure 3b) shows the point in time at which the contact points 315-317 of the contact bridge 31 come into contact with the fixed contacts 21, 22. In principle, a movement of the actuating plunger 2 could stop at this point in time, since at this point in time there is contact between the fixed contacts 21, 22 and the contact points 314-317, thus establishing an electrically conductive path between the first fixed contact 21 and the second fixed contact 22. However, to further increase the reliability of the snap-action switch according to the present application, the contact points formed by the contact points 314-317 and the fixed contacts 21, 22 are designed to be self-cleaning. This means that particles, deposits, or deposits caused by the burning of the materials on the fixed contacts 21, 22 or the contact points 314-317 are mechanically loosened and pushed away.In the present exemplary embodiment, this is achieved by moving the actuating plunger 2 further in the direction shown, starting from the situation shown in Figure 3b), in which contact already exists between the contact points 314-317 and the fixed contacts 21, 22, whereby the spring-elastic contact bridge 31 is slightly bent open, resulting in a lateral movement between the fixed contacts 21, 22 and the contact points 314-317. This lateral movement guides the contact points 314-317 along the fixed contacts 21, 22, so that the friction generated at the contact points loosens deposits and particles and pushes them outwards. In this way, a permanently low contact resistance between the contact points 314-317 and the fixed contacts 21, 22 is ensured, thus increasing the reliability of the snap-action switch 100.

[0076] In addition, the contact bridges 31, 32 formed with individual bridge legs 311, 312 ensure that in the event of deposits and particles on one of the contact partners, height compensation can take place due to the spring-elastic design of the contact bridge - also between the individual legs 311, 312 for contacting a fixed contact 21, 22 - whereby an electrical contact is closed even more reliably.

[0077] Figures 4a) to c) show an opening process of the contact bridge 31 from Figure 3.

[0078] Figure 4a) shows the situation reached in Figure 3c) after the complete closing of the contact bridge 31 from Figure 3. As indicated by the arrows drawn in Figures 4a) to c), the actuating plunger 2 now moves downwards, i.e. away from the fixed contacts 21, 22, so that an electrical connection between the fixed contacts 21, 22 and the contact points 314-317 of the contact bridge 31 is released again. It is assumed here that the contact points 314-317 are welded to the fixed contacts 21, 22 due to thermal stress from the flowing currents and thus adhere to them and do not detach immediately when the contact bridge 31 rests against the reinforcing arms 25, 26.

[0079] Figure 4b) shows the position of the actuating plunger 2 in which the bridge legs 311, 312 of the contact bridge 31 rest against the reinforcing arms 25, 26 of the actuating plunger 2 and then, by further movement of the actuating plunger 2 in the direction away from the fixed contacts 21, 22, the contact points 314-317 are released from the fixed contacts 21, 22. By further movement of the actuating plunger 2, the force is introduced into the contact bridge 31 via the reinforcing arms 25, 26 in the direction of movement. The reinforcing arms 25, 26 additionally reinforce and stiffen the contact bridge 31 in this direction. In this way, it is possible to apply an increased opening force to the welded contact point, contrary to the spring-elastic design of the contact bridge 31, so that it is reliably opened.

[0080] In this embodiment, the contact points 314-317 are deducted from the fixed contacts 21, 22, ie a tensile force acts in the contact bridge 31.

[0081] Figures 5a) and 5b) show an alternative embodiment of a contact bridge 31 during closing (Figure 5a)) and opening (Figure 5b)).

[0082] In the embodiment shown in Figure 5, the contact bridge 31 has an overall convex design, with the reinforcing arms 25, 26 arranged on the actuating plunger 2 being correspondingly inclined downwards. The fixed contacts 21, 22 are also inclined relative to the horizontal in the region of the contact points 314-317 in accordance with an inclination of the contact bridge 31, so that, as shown in Figure 5a), upon contact between the contact points 314-317 and the fixed contacts 21, 22, self-cleaning does not lead to the displacement of particles as in the embodiment according to Figure 3, but rather, due to the changed contact situation, this lateral movement between the contact points 314-317 and the fixed contacts 21, 22 is a pulling movement directed towards the actuating plunger 2.

[0083] According to the changed contact situation, the contact points 314-317 are pushed off the fixed contacts 21, 22 as shown in Figure 5b) when opening, ie a compressive force acts in the contact bridge which releases the contact points 314-317 from the fixed contacts 21, 22.

[0084] In contrast to the configuration of contact points 314-317 shown in Figures 2-4, in the configuration shown in Figure 5, contact points 314-317 are designed as flat contacts and fixed contacts 21, 22 are designed as cylindrical contacts. Figure 6 shows a more detailed illustration of another configuration of contact bridge 31, which can also be used in an arrangement according to Figure 1.

[0085] The contact bridge 31 shown in Figure 6 is designed as an H-bridge with a first bridge leg 311 and a second bridge leg 312. The bridge legs 311, 312 are centrally connected to one another by the crosspiece 313 and are each divided into two bridge leg sections 311a, 311b, 312a, 312b extending from the crosspiece 313.

[0086] In the present embodiment, the crosspiece 313 is arranged centrally, so that the bridge leg sections 311a, 311b, 312a, 312b each extend symmetrically from the crosspiece 313 and at right angles to it. As already explained with reference to the embodiment of Figure 2, the bridge legs 311, 312 are initially designed with a positive curvature and then extend with a negative curvature, so that the contact bridge 31 is concave in a central region and convex in the end regions of the bridge legs 311, 312. The contact points 314-317 are arranged at the ends of the bridge legs 311, 312; in the present embodiment, these are designed as contact rivets. Compared to soldered contacts, contact rivets have the advantage that they can be produced using different manufacturing processes. This means that other material combinations are possible.As the name "contact rivets" suggests, the contact points 314-317 are attached to the respective bridge leg end with a rivet.

[0087] In the present exemplary embodiment, the crossbar 313 is designed such that it extends linearly between the bridge legs 311, 312 with a semicircular formation on both sides of the bridge legs 311, 312. This formation can be used to align and center the contact bridge 31 within the actuating plunger 2 and thus represents an assembly aid. Figure 7 shows a further exemplary embodiment of a contact bridge 31, wherein the contact bridge 31 shown in Figure 7 has a completely convex profile. The convex profile of the contact bridge 31 requires a modified contact geometry and self-cleaning, as shown, for example, in Figure 5. In the exemplary embodiment of Figure 7, the contact points 314-317 are also designed as contact rivets.

[0088] Figures 8a) and 8b) show a modified embodiment of the contact bridge 31 from Figure 6.

[0089] In contrast to the design of the contact bridge 31 shown in Figure 6, in which both bridge legs 311, 312 are designed to run parallel, the contact bridge 31 according to Figure 8a) is designed such that one bridge leg is designed to be leading and the other bridge leg to be lagging.

[0090] In this context, "leading" means that the contact point located on the leading bridge leg contacts the associated fixed contact before the lagging contact point during a movement in the closing direction, thus establishing an electrically conductive connection before the lagging contact point. Conversely, the lagging bridge leg or its associated contact points are the first to detach from the associated fixed contact when the switch position is opened, and the leading bridge leg in the closing direction is the second to break the connection.

[0091] In the embodiment shown in Figure 8, the first bridge leg 311 and thus also the contact points 314, 316 assigned to it are designed to be leading, and the second bridge leg 312 with the assigned contact points 315, 317 are designed to be lagging. This configuration results in increased current densities and the associated arcing and the resulting erosion when the contacts open, essentially affecting the contact points of the leading, first bridge leg 311. By selecting a suitable material, the leading bridge leg can thus, for example, be equipped with contact points made of a material that is more resistant to erosion, whereas the lagging bridge leg can be provided with contact points made of a very well-conducting material, but with significantly more erosion and thus a more sensitive material to arcing.

[0092] Figure 8b) shows an enlarged detail from Figure 8a), which clearly shows how a leading and a trailing bridge leg can be realized. In the present exemplary embodiment, the bridge legs are bent in such a way that the first bridge leg section 311b, shown here as an example, projects beyond the second bridge leg section 312b in the closing direction by a height Ah and is thus leading in the closing direction.

[0093] In an alternative design, the contact rivets used could also have different heights, so that while the bridge legs are bent equally, the contact rivets used for the leading contact point have a greater height than the contact rivets for the trailing contact point. Such a design can provide a greater material thickness for the leading contact point, so that in addition to a material that is more resistant to erosion, it also has an additional material thickness that can be worn away.

[0094] List of reference symbols

[0095] Housing

[0096] Actuating plunger

[0097] Actuating element

[0098] Compression spring First positive opening lever Second positive opening lever First snap spring Second snap spring , 12 Receiving notch , 14 Spacer Upper contact arm Lower contact arm First contact point Second contact point Third contact point Fourth contact point First fixed contact Second fixed contact Third fixed contact Fourth fixed contact , 26 Reinforcing arm First contact bridge Second contact bridge 0 Snap switch 1 First bridge leg 2 Second bridge leg 3 Crossbar

Claims

Snap-action switch (100) with a housing (1), an actuating plunger (2) having two switching positions with at least one contact bridge (31, 32) for electrically connecting at least a first contact pair (23, 24) in a switching position, and with snap-action springs (8, 9) which are supported on an actuating element (3) and the actuating plunger (2) essentially symmetrically under pretension, the lines of action of which are displaceable by the actuating element (3) in such a way that the actuating plunger (2) can be snapped over from a first switching position, in which the actuating plunger (2) is essentially in the rest position, into a second switching position, in which the actuating plunger (2) is essentially in the actuated position, wherein the snap-action switch (100) further comprises a positive opening arrangement,by means of which a switching at least from the first to the second switching position is forced upon exceeding a positive opening force on the actuating element (3), characterized in that the at least one contact bridge (31, 32) has at one end and at the other end at least two contact points (17, 18, 19, 20) for electrically contacting the first contact pair (23, 24) in parallel, wherein each of the contact points (17, 18, 19, 20) is designed to completely switch a rated electrical power of the snap-action switch (100). Snap-action switch (100) according to claim 1, characterized in that the snap-action switch has two contact bridges (31, 32) for electrically connecting at least the first contact pair (23, 24) and at least one second contact pair (21, 22), wherein the contact points of the second contact bridge are also designedto completely switch an electrical rated power of the snap switch (100). Snap switch (100) according to claim 2, characterized in that in the first switching position, the first contact pair and in the second, Switching position, the second contact pair (21, 22) is connected. Snap-action switch (100) according to one of the preceding claims, characterized in that the contact bridges (31, 32) are each formed in one piece. Snap-action switch (100) according to one of the preceding claims, characterized in that the contact bridges (31, 32) are designed in the form of a double H-bridge, each with two bridge legs (311, 312) on either side of the actuating plunger (2) and at least one transverse web (313). Snap-action switch (100) according to one of the preceding claims, characterized in that the contact bridges (31, 32) are designed such that on either side of the actuating plunger (2) one bridge leg (311) is designed to be leading and the other bridge leg (312) is designed to be lagging. Snap-action switch (100) according to one of the preceding claims, characterized in that the contact bridges (31, 32) are spring-elastic.Snap-action switch (100) according to one of the preceding claims, characterized in that the contact bridges (31, 32) are designed in such a way and the contact points (17, 18, 19, 20) are arranged in such a way, and relative to the contact pairs (21, 22, 23, 24), that the contacts are self-cleaning. Snap-action switch (100) according to claim 8, characterized in that the contact points (17, 18, 19, 20) and the contact pairs are designed in such a way. and are arranged relative to one another such that, at least when the contacts are closed, a lateral movement is effected between the contact point (17, 18, 19, 20) and the contact pair. Snap-action switch (100) according to one of the preceding claims, characterized in that a reinforcement arrangement is assigned to each of the at least two contact bridges (31, 32) in the opening direction. Snap-action switch (100) according to claim 10, characterized in that the reinforcement arrangement (25, 26) is arranged on the actuating plunger (2). Snap-action switch (100) according to one of claims 8, 10 or 11, characterized in that the reinforcement arrangement is formed integrally with the actuating plunger (2).Snap-action switch (100) according to one of claims 8 to 10, characterized in that the reinforcement arrangement is designed as a molded-on portion extending from the actuating plunger (2) in the direction of an extension direction of the contact bridge (31, 32), in particular in the form of reinforcement arms (25, 26). Snap-action switch (100) according to claim 13, characterized in that the molded-on portions support the bridge legs, at least in the contacted state, by at least 1 / 5, preferably at least 1 / 4, more preferably at least half, particularly preferably 3 / 4. Snap-action switch (100) according to one of claims 13 or 14, characterized in that. the projections are designed such that the contact bridges are prestressed. Snap-action switch (100) according to one of claims 13 to 15, characterized in that the projections are dimensioned such that an opening force of at least 10 N, preferably at least 20 N, more preferably at least 30 N can be transferred to the bridge legs (311, 312).

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