Temperature-dependent switch
The temperature-dependent switch addresses issues of defects and contact resistance by using a spacer element to fix the spring element, improving lifespan and consistency through reduced mechanical stress and simplified assembly.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- ホフセス マルセル ペー
- Filing Date
- 2024-10-09
- Publication Date
- 2026-07-30
AI Technical Summary
Existing temperature-dependent switches suffer from increased defects and contact resistance due to permanent electrical connections between the spring element and the energized switch housing, leading to reduced service life and inconsistent switching temperatures.
A temperature-dependent switch design that fixes the spring element in place using a spacer element within the switch housing, allowing it to perform multiple functions, including supporting the bimetallic element in the high-temperature state, thereby simplifying assembly and reducing mechanical stress.
The design enhances the switch's lifespan and maintains consistent switching temperatures by minimizing mechanical wear and contact resistance, while allowing for easy assembly and adaptability to various technical specifications.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a temperature-dependent switch.
Background Art
[0002] In principle, a number of temperature-dependent switches are already known. Exemplary temperature-dependent switches are disclosed in German Patent Publication No. 10 2013 109 291 and German Patent No. 10 2011 119 637.
[0003] Such temperature-dependent switches are mainly used in known ways to monitor the temperature of a device. For this purpose, the switch is thermally contacted with the device to be protected, for example via one of its outer surfaces, such that the temperature of the device to be protected affects the temperature of the switching mechanism disposed inside the switch.
[0004] The switch is generally electrically connected in series to the supply circuit of the device to be protected via a connecting cable, such that below the response temperature of the switch, the supply current of the device to be protected flows through the switch.
[0005] In the switch disclosed in German Patent Publication No. 10 2013 109 291, the switching mechanism is disposed inside the switch housing. The switch housing is a closed housing in which the switching mechanism is sealed against the outside. The switch housing is formed in two parts. The two parts comprise a lower part that is closed by a cover part. The cover part is fixed to the lower part. For this purpose, the lower part comprises a raised, circumferential edge, and the free upper edge of the lower part is bent or flanged onto the cover part.
[0006] The temperature-dependent switching mechanism, located within the switch housing, comprises a spring element with a fixed movable contact and a bimetallic element that interacts with the movable contact. The spring element presses the movable contact against a fixed, opposing contact located inside the switch housing, which is provided in the cover. The outer edge of the spring element, configured as a snap-action spring disc, is supported at the bottom of the switch housing, and current flows from the bottom through the snap-action spring disc and the movable contact to the fixed, opposing contact, and then to the cover.
[0007] Temperature-dependent bimetallic elements, such as switches having a disk-shaped configuration and often referred to as bimetallic snap-operated disks, disclosed in German Patent Publication 10 2013 109 291 and German Patent 10 2011 119 637, are fundamentally involved in the temperature-dependent switching behavior of switching mechanisms. These bimetallic elements are typically configured as multilayer active sheet-like devices consisting of two, three, or four interconnected components having different coefficients of thermal expansion. The connections between the individual metal or metal alloy layers in this type of bimetallic element are typically material locking or positive locking connections, achieved, for example, by rolling.
[0008] Such a bimetallic element has a first geometric configuration (low-temperature configuration) that is stable at low temperatures below the response temperature of the bimetallic element, and a second geometric configuration (high-temperature configuration) that is stable at high temperatures above the response temperature of the bimetallic element. The bimetallic element snaps (changes abruptly) from its low-temperature configuration to its high-temperature configuration in a temperature-dependent manner in the form of hysteresis.
[0009] Therefore, if the temperature of the bimetallic element rises above its response temperature as a result of the temperature rise of the device being protected, the bimetallic element snaps from its low-temperature configuration to its high-temperature configuration. This causes the bimetallic element to act on the spring element to lift the movable contact from the fixed opposing contact, resulting in the switch opening and the device to be protected being switched off and unable to heat up any further.
[0010] Unless a reset lock is provided, the bimetallic element snaps back to its low-temperature configuration, and as a result, the switch closes again as soon as the temperature of the bimetallic element drops below the so-called reset temperature of the bimetallic element as a result of cooling the device to be protected.
[0011] In this low-temperature configuration, the bimetallic element is preferably mounted within the switch housing in a manner that does not apply mechanical force, and the bimetallic element is not used to conduct current. This has the advantage that the bimetallic element has a longer service life, and the switching point, i.e., the response or switching temperature of the bimetallic element, does not change even after many switching cycles.
[0012] In the switches disclosed in German Patent Publication No. 10 2013 109 291 and German Patent No. 10 2011 119 637, a spring element configured as a snap-action spring disc is permanently in contact with the lower part in the region of its outer edge. In the switch disclosed in German Patent No. 10 2011 119 637, a portion of the outer edge of the snap-action spring disc is connected to the lower part of the switch housing in a material locking manner. In the switch disclosed in German Patent Publication No. 10 2013 109 291, the snap-action spring disc is placed on a circumferential shoulder provided at the lower part and is clamped between this shoulder and a spacer element configured as a spacer ring, thereby mechanically fixed. Therefore, the snap-action spring disc is permanently electrically connected to the current-carrying switch housing in both the low-temperature and high-temperature states of the switching mechanism.
[0013] The permanent electrical connection between the snap-action spring disc and the current-carrying lower part of the switch housing ensures very low contact resistance between the snap-action spring disc and the lower part of the switch housing. This eliminates a possible source of error that could occur during the final continuity test of a fully assembled temperature-dependent switch. Due to manufacturing tolerances, the contact resistance between the lower part of the housing and the snap-action spring disc can be very high, potentially resulting in the finished temperature-dependent switch being discarded as unacceptable.
[0014] Conversely, most switches known from the prior art have a spring element mounted on an inner base at the bottom of the switch housing, or on a circumferentially extending shoulder at the bottom, so that its edge is loose, i.e., can move freely. Such a switch is disclosed, for example, in German Patent Publication No. 43 45 350. It is understood that such a loosely supported spring element has a greater degree of mechanical freedom, and therefore the spring element can move more freely within the switch housing when the switching mechanism snaps from low and high temperatures (and vice versa). This has a fundamentally positive effect on the service life of the switching mechanism and the long-term consistency of its switching temperature. However, a permanent electrical connection between the spring element and the energized switch housing, which is not provided here, results in the aforementioned disadvantages, namely, increased defects and increased contact resistance. [Overview of the project] [Problems that the invention aims to solve]
[0015] Therefore, an object of the present invention is to provide a temperature-dependent switch in which the above-mentioned drawbacks are prevented or at least reduced as much as possible in a structurally simple manner. In this regard, an object is to provide a switch that is composed of as few components as possible, is easy to install, and whose service life and / or switching capacity can be increased compared to temperature-dependent switches currently known. [Means for solving the problem]
[0016] According to the present invention, this objective is solved by the temperature-dependent switch described in claim 1, which comprises the following devices. A switch housing having a lower part and a cover part that closes the lower part, A temperature-dependent switching mechanism comprising a movable contact portion, a bimetallic element and a spring element interacting with the movable contact portion, configured to switch between a low-temperature state and a high-temperature state, wherein in the low-temperature state, the movable contact portion is pressed against a contact surface located inside the switch housing to establish an electrical connection between a first electrical terminal and a second electrical terminal of the switch, and in the high-temperature state, the movable contact portion is separated from the contact surface to interrupt the electrical connection between the first electrical terminal and the second electrical terminal. The switch housing includes a spacer element positioned between the lower part and the cover part inside the switch housing. At least a portion of the spring element is positioned between the spacer element and the switch housing and is fixed in place by the interaction between the spacer element and the switch housing. At least a portion of the bimetallic element is positioned between the spring element and the spacer element and is supported on the spacer element when the switching mechanism is at a high temperature.
[0017] Similar to the switch disclosed in German Patent Publication No. 10 2013 109 291, the spring element of the temperature-dependent switching mechanism in the switch according to the present invention is also fixed in place by a spacer element located inside the switch housing. More precisely, the spring element is fixed in place by the interaction between the spacer element and the switch housing. This means that both the spacer element and the switch housing contribute to fixing the position of the spring element. Both the spacer element and the switch housing apply force to the spring element, fixing it in place. Although not necessarily required, the spacer element and the spring element can be in direct contact, and the switch housing and the spring element can be in direct contact. The switch housing and the spacer element can also be indirectly connected to the spring element.
[0018] However, unlike the switch disclosed in German Patent Publication No. 10 2013 109 291, the spacer element in the switch according to the present invention performs several functions simultaneously. It performs two already known functions, namely, being configured to hold the lower part and the cover part apart from each other, and being configured to fix the spring element in its position. According to the present invention, the spring element also functions as a third function, namely, a contact part that can support the bimetallic element in the high-temperature state of the switching mechanism.
[0019] Therefore, a single component in the form of a spacer element can perform several functions simultaneously. This not only simplifies the structural configuration of the switch but also simplifies its assembly. The latter additional function of the switch as a contact point of the bimetallic element also has a positive effect on the lifespan of the switch.
[0020] In the above switch, the bimetal element in its high-temperature state is usually supported either on the spring element itself or on the cover part of the switch housing. Supporting the bimetal element on the spring element has the drawback that it is subject to high mechanical stress and may be damaged especially after a large number of switching cycles. In contrast, support on the cover part of the switch housing is less of a problem. On the one hand, the switching mechanism has to fit very precisely to the manufacturing tolerances of the housing components, and on the other hand, the bimetal element with its high-temperature configuration usually has to bend very strongly until its outer edge reaches the cover part and its central part presses down the movable contact part.
[0021] However, by using the abutting part provided on the spacer element, the manufacturing tolerances of the switching mechanism will be almost independent of the manufacturing tolerances of the switch housing. Furthermore, since the spacer element can be arranged very close to the bimetal element and the spring element, the bimetal element only has to bend slightly. The spacer element can be configured, for example, to be much more stable than the spring element, so mechanical wear of the spacer element is also harmless.
[0022] The above-described advantages resulting from the permanent electrical connection between the spring element and the switch housing through which current flows can also be achieved by the spacer element in the switch according to the invention.
[0023] In this way, the above object is completely solved.
[0024] In the high-temperature state of the switching mechanism, the spring element is supported on the spacer element, but in the low-temperature state of the switching mechanism, it is preferably arranged spaced apart from the spacer element. Thus, the spring element does not contact the spacer element in the low-temperature state of the switch.
[0025] In a refinement, at least a part of the spring element that is arranged between the spacer element and the switch housing and is fixed in a predetermined position by the interaction between the spacer element and the switch housing includes the outer edge of the spring element.
[0026] In other words, the spring element is preferably fixed in its edge position by the interaction between the spacer element and the switch housing. Particularly preferably, at least a part of the spring element includes the radially outer edge of the spring element. This has the advantage of mounting the spring element in a space-saving manner at the edge, while on the other hand, the switching mechanism can freely access the central region of the spring element.
[0027] In a further improvement example, at least a part of the bimetal element disposed between the spring element and the spacer element and supported on the spacer element in the high-temperature state of the switching mechanism includes the outer edge of the bimetal element.
[0028] In other words, in the high-temperature state of the switching mechanism, the outer edge of the bimetal element abuts against the spacer element. In the low-temperature state of the switching mechanism, it is preferable that this outer edge is separated from the spacer element. Thereby, the switching mechanism can be arranged in a space-saving manner as much as possible. Furthermore, the spacer element can be arranged at the radially outer edge of the switching mechanism in order to save space without interfering with other components of the switching mechanism.
[0029] In a further improvement example, at least a part of the spring element disposed between the spacer element and the switch housing is (i) directly or indirectly clamped between the spacer element and the lower part, or (ii) directly or indirectly clamped between the spacer element and the cover part.
[0030] Such a clamping configuration between the spacer element and the lower part, or between the spacer element and the cover, is particularly easy for achieving the positioning and fixing of the spring element. In this way, the spring element can be simply inserted into the switch housing at the desired position during switch assembly, the spacer element can be positioned on the upper or lower side, and then the switch housing can be closed by fixing the cover to the lower part, or vice versa. Then, as soon as the cover is fixed to the lower part, the position of the spring element is automatically fixed. This requires no additional effort in the assembly process.
[0031] "Indirectly clamped" means that the spring element is clamped by the spacer element and the lower part, or by the spacer element and the cover, but does not necessarily have to be in direct contact with these two components. Furthermore, housing components or elements can be placed between the two components. In particular, for example, insulating foil or other intermediate layers can be placed between the aforementioned components.
[0032] In a further improvement, the spacer element includes a spacer ring.
[0033] The spacer element is preferably configured as a spacer ring. Therefore, the spacer element can be configured as a standard device. No additional cost is incurred by providing the spacer element, or if there is any, it is minimal. The spacer element itself can be made of a conductive material (e.g., metal) or a non-conductive material (e.g., plastic).
[0034] In a further improvement, the spacer element has a substantially L-shaped cross-section.
[0035] Regarding "substantially L-shaped cross-section," this term means that the cross-sectional area of the spacer element includes a shape at least similar to an L. Preferably, the shape of the cross-sectional area corresponds to an L shape.
[0036] In a further improvement, the first side of the spring element facing the bimetallic element faces the contact surface.
[0037] Thus, the bimetallic element is positioned on the same side of the spring element where the contact surfaces of the fixed opposing contacts are located. If the contact surfaces of the fixed opposing contacts are located above the spring element, the bimetallic element is also positioned above the spring element. On the other hand, if the contact surfaces of the fixed opposing contacts are located below the spring element, the bimetallic element is also positioned below the spring element. This has the advantage that the bimetallic element and the spring element can be curved in the same direction, both in the low-temperature and high-temperature states of the switching mechanism. In the high-temperature state of the switching mechanism, the center of the bimetallic element is pressed directly against, for example, the central region of the spring element, and the movable contact is lifted away from the contact surfaces of the fixed opposing contacts.
[0038] In a further improved example, the spacer element has a support surface that protrudes from the first side of the spring element in a first direction and supports at least a portion of the bimetallic element in the high-temperature state of the switching mechanism, the support surface being oriented laterally, preferably orthogonal to the first direction.
[0039] In this case, the term "lateral" does not necessarily mean orthogonal or perpendicular. Instead, it is understood to mean any type of orientation that is not parallel. Therefore, oblique orientation at an angle not equal to 0° also falls under the term "lateral."
[0040] In the low-temperature state of the switching mechanism, it is preferable that at least a portion of the bimetallic elements are spaced apart from the support surface.
[0041] As described, the cross-sectional shape of the spacer element is essentially L-shaped, so it very easily functions as a kind of retaining claw that can support the bimetallic element at its edge when the switching mechanism is at high temperature. At the same time, the spacer element is preferably housed flat on the spring element and functions as a retainer for the spring element, thereby fixing the spring element in place within the switch housing.
[0042] In a further improved version, the spacer element is clamped within the switch housing by the interaction between the lower part and the cover.
[0043] This has the advantage that the spacer element is automatically locked in place after the switch housing is closed. This also automatically locks at least a portion of the spring element in place after the switch housing is closed. The spacer element can be clamped directly or indirectly between the lower part and the cover. If both the lower part and the cover, as well as the spacer element, are made of conductive material, an insulating element, preferably in the form of an insulating foil, is placed at least between the spacer element and the lower part, or between the spacer element and the cover.
[0044] In a further improved example, the spring element includes at least one compensating portion between the outer edge and the inner region, the compensating portion being configured to be radially elastic, thereby allowing for mechanical deformation of the spring element.
[0045] At least one compensating component has the advantage of compensating for, or at least reducing, internal deformation that may occur due to clamping of the edges of the spring element when the switching mechanism shifts. Such internal deformation and the resulting internal forces would, without the compensating component, lead to mechanical stress and aging of the spring element, limiting the service life of the equipped switch.
[0046] Such a "compensating portion" is understood to be a region of the spring element that, in this case, cannot move radially, or can only move very slightly, because the outer edge of the spring element is firmly fixed, but is configured to bend or bend radially, allowing for radial avoidance or expansion motion within the spring element. Therefore, the compensating portion can also be called an expansion structure.
[0047] In further improvements, the movable contact part is fixed to the spring element using a material locking mechanism.
[0048] For example, the movable contact portion is soldered or welded to the spring element. This prevents the contact portion from slipping during assembly, enabling simple and inexpensive assembly of the switching mechanism. Preferably, the movable contact portion is positioned in the center or intermediate region of the spring element.
[0049] In a further improvement, the bimetallic element is held in a constrained state with some play on the movable contact (and spring element).
[0050] This means that since the spring element, bimetallic element, and movable contact part form a unit, the switching mechanism can be assembled and temporarily stored as separate semi-finished parts. Furthermore, although the bimetallic element is fixed to the movable contact part, it has play, meaning it loosens according to this play, allowing it to deform unimpeded between low-temperature and high-temperature configurations, thus enabling individual checks of the switching mechanism.
[0051] In further improvements, the bimetallic element and the spring element are each essentially disc-shaped, and the movable contact portion is fixed to the center of the spring element. In a particularly preferred embodiment, both the spring element and the bimetallic element are each disc-shaped.
[0052] In a further improvement, the first electrical terminal of the switch is positioned on the outside of the cover, and the second electrical terminal of the switch is positioned on the outside of the bottom.
[0053] This ensures that temperature-dependent switches can be easily connected electrically.
[0054] In further improvements, the lower part includes a flanged or bent free upper edge on the cover.
[0055] This results in the simplest and most stable type of fastening between the lower part and the cover, as can be seen, for example, from German Patent Publication No. 10 2013 109 291.
[0056] It should be understood that the features described above and those described below can be used not only in the combinations shown in each case, but also in other combinations, or individually, without departing from the scope of the present invention. [Brief explanation of the drawing]
[0057] Embodiments of the present invention are shown in the drawings and will be described in more detail in the following description. [Figure 1] A schematic cross-sectional view of a temperature-dependent switch according to the first embodiment, wherein the switch is in its low-temperature state. [Figure 2] Figure 1 is a schematic cross-sectional view of a temperature-dependent switch, where the switch is in its high-temperature state. [Figure 3] A schematic cross-sectional view of a temperature-dependent switch according to a second embodiment, wherein the switch is in its low-temperature state. [Figure 4] A schematic cross-sectional view of a temperature-dependent switch according to a third embodiment, the switch in its low-temperature state. [Figure 5] A schematic cross-sectional view of a temperature-dependent switch according to a fourth embodiment, wherein the switch is in its low-temperature state. [Figure 6] This is a schematic cross-sectional view of a temperature-dependent switch according to the fifth embodiment, where the switch is in its low-temperature state. [Modes for carrying out the invention]
[0058] Figures 1 to 6 show five different embodiments of the switch according to the present invention, each shown in a schematic cross-sectional view. In each case, the entire switch is indicated by reference numeral 10.
[0059] The switch 10 is configured to be rotationally symmetric and has a circular shape when viewed from above. The switch 10 comprises a switch housing 12 in which a temperature-dependent switching mechanism 14 is located. The switch housing 12 has a pot-shaped lower portion 16, which is closed by a cover portion 18. The lower portion 16 has a raised edge portion 20, which is bent inward or flanged in the region of its free upper end, thereby clamping or fixing the cover portion 18 to the lower portion 16 with an insulating foil 22 interposed therebetween.
[0060] The lower portion 16 and the cover portion 18 are made of a conductive material, preferably metal. In the embodiment shown herein, the lower portion 16 is a housing made of deep-drawn steel, which provides relatively high voltage resistance. Insulating foil 22 is placed between the lower portion 16 and the cover portion 18, and these serve to electrically insulate the two switch housing components 16 and 18.
[0061] The cover portion 18 completely closes the lower portion 16. In addition to electrical insulation, the insulating foil 22 also ensures a sufficient mechanical seal between the lower portion 16 and the cover portion 18, thereby sealing the inside of the switch housing 12 from the outside. This prevents liquids and impurities from entering the inside of the housing from the outside.
[0062] The switching mechanism 14, located inside the switch housing, includes a temperature-independent spring element 24 and a temperature-dependent bimetallic element 26. The spring element 24 is preferably configured as a circular, disc-shaped snap-action spring disc.
[0063] The temperature-dependent bimetallic element 26 is preferably configured as a bimetallic disk, which has two temperature-dependent configurations: a geometrically low-temperature configuration (see Figure 1) and a geometrically high-temperature configuration (see Figure 2). In the central region 28 of the spring element 24, a contact portion 30 is fixed to the spring element 24. This contact portion 30 is connected to the spring element 24 in a material locking manner. For example, the contact portion 30 is welded or soldered to the spring element 24. Since the contact portion 30 moves with the spring element 24 relative to the switch housing 12 during switching operation, the contact portion 30 is also called a “movable contact portion”.
[0064] The bimetallic element 26 is constrained and held on the movable contact portion 30 with some play. The through hole 32 in the center of the bimetallic element 26 has an inner diameter slightly larger than the outer diameter of the movable contact portion 30 located in its lower region. However, in the upper region, the outer diameter of the movable contact portion 30 is larger than the inner diameter of the through hole 32, and since the spring element 24 is positioned below the bimetallic element 26 and firmly connected to the movable contact portion 30, the bimetallic element 26 cannot unintentionally detach from the switching mechanism 14 despite its degree of freedom of movement. Thus, the spring element 24, the bimetallic element 26, and the movable contact portion 30 can be manufactured in advance as semi-finished products and inserted as a whole into the switch housing 12 during the assembly of the switch 10, illustrating a constrained unit of the switching mechanism 14.
[0065] In the low-temperature state of the switching mechanism 14 shown in Figure 1, the spring element 24 presses the movable contact portion 30 against the contact surface 34 located below the fixed contact portion 36. In the embodiment shown in Figure 1, the fixed contact portion 36 is located on the bottom side 38 of the cover portion 18 facing the lower part 16.
[0066] In the region of the radial outer edge 40 of the spring element 24, the spring element 24 is fixed within the switch housing 12. More precisely, the radial outer portion 42 forming the outer edge 40 of the spring element 24 is clamped between the spacer element 44 and the lower part 16 of the switch housing 12 in the embodiment shown in Figure 1. The spacer element 44 itself is also clamped between the lower part 16 and the cover part 18 within the switch housing 12. The spacer element 44 is indirectly clamped between the lower part 16 and the cover part 18 and is directly positioned between the spring element 24 and the insulating foil 22.
[0067] When assembling the switch 10 shown in Figure 1, the switching mechanism 14 is first inserted into the lower part 16. Next, the spacer element 44 is placed on the outer edge portion 42 of the spring element 24, and then the cover portion is placed on the spacer element 44 with the insulating foil 22 in between. Finally, the upper raised edge portion 20 of the lower part is bent inward or flanged, so that the cover portion 18 is pressed from above against the spacer element 44, and the spacer element 44 is similarly pressed against the spring element 24, thereby fixing the spring element 24 in place within the switch housing 12. It will be understood that while the fixing of the position only affects the outer edge portion 42 of the spring element 24, the central region 28 of the spring element 24, along with the movable contact portion 30, remains movable within the switch housing 12.
[0068] The spacer element 44 is configured as a spacer ring having an L-shaped cross-section. This spacer ring 44 protrudes from a first side surface 48 of the spring element 24 in a first direction, where the first direction corresponds here to the vertical direction, schematically shown in Figure 1 by arrow 46. This first side surface 48 of the spring element 24 is the (upper) side of the spring element 24 that faces the bimetal element 26 and the contact surface 34.
[0069] The spacer element 44 is oriented laterally with respect to the first direction 46 and further comprises a support surface 50 facing the bimetal element 26.
[0070] The outer portion 52 of the bimetallic element 26, including its outer edge 54, is positioned between the spring element 24 and the spacer element 44. More specifically, this outer portion 52 of the bimetallic element 26 is positioned between the support surface 50 and the spring element 24. This outer portion 52 keeps the bimetallic element 26 in a high-temperature state on the spacer element 44 or on the support surface 50 positioned thereon (see Figure 2).
[0071] In the closed switching position of the switch 10 shown in Figure 1, when the switching mechanism 14 is in a low-temperature state, the spring element 24 thus presses the movable contact portion 30 against the contact surface 34 located on the fixed contact portion 36. The spring element 24, having its outer edge portion 42, is in permanent electrical contact with the lower portion 16, so that the switching mechanism 14 establishes a conductive connection between the first terminal 56 and the second terminal 58 in the low-temperature state shown in Figure 1. The first terminal 56 is, for example, the outside of the cover portion 18. If the cover portion 18 is not entirely made of metal, only a portion of it may be made of metal or a conductive material, and this portion is connected to the fixed contact portion 36 and led to the outside. For example, a shoot-through contact can be located on the cover portion 18 above the fixed contact portion 36, as known from, for example, German Patent No. 103 01 803. In the switch 10 shown in Figure 1, it is preferable that the outside of the lower portion 16 functions as the second terminal 58.
[0072] In the low-temperature state of the switch 10, the current flows from the first terminal 56 through the cover portion 18 to the fixed contact portion 36, from there through the movable contact portion 30 and the spring element 24 to the lower portion 16, and ultimately to the second terminal 58 (or vice versa). In this low-temperature state of the switch 10, the bimetallic element 26 is housed in a state where it is less or less subjected to force.
[0073] Starting from the situation shown in Figure 1, if the temperature of the device to be monitored by the switch 10, and consequently the temperature of the switch 10 and switching mechanism 14 used therein, rises above the response temperature of the bimetal element 26, the bimetal element 26 snaps (changes abruptly) from its low-temperature configuration shown in Figure 1 to its high-temperature configuration shown in Figure 2. The upper side of the bimetal element 26 snaps from a convex curvature to a concave curvature as a result. The bimetal element 26 is then supported from below with its outer edge portion 52 resting on the support surface 50 of the spacer element 44. Simultaneously, the bimetal element 26 presses the movable contact portion 30 downward at its center, lifting the contact portion 30 from the contact surface 34. During this switching movement, the bimetal element 26 acts against the force applied to the contact portion 30 by the spring element 24 in the low-temperature state. As a result, the spring element 24 also snaps from its upper first convex shape shown in Figure 1 to its upper concave shape shown in Figure 2.
[0074] This interrupts the current flowing through switch 10. Therefore, the switch is open.
[0075] It is preferable that the spring element 24 has several compensating portions 60 to give the possibility that the spring element 24 can mechanically expand when snapping over from the situation shown in Figure 1 to the situation shown in Figure 2, even though its edges are clamped. These compensating portions 60 allow the spring element 24 to expand and compress radially, and in particular prevent tension or deformation inside the spring element 24. The compensating portions 60 may have a configuration similar to that disclosed in German Patent Publication No. 10 2013 109 291.
[0076] A further advantage of the fixed clamping of the outer edge 40 of the spring element 24 is that the permanent mechanical and electrical connection between the spring element 24 and the switch housing 12 means that sparks and arc discharges do not occur during switching operation, as is often the case with switching mechanisms where the edge of the spring element lifts away from the switch housing during switching operation. This effectively prevents burnout of the contacts.
[0077] Figure 3 shows a schematic cross-sectional view of a second embodiment of the switch 10. Here, the switch 10 is again shown in a low-temperature state, in which case the switching mechanism 14 establishes a conductive connection between the first terminal 56 and the second terminal 58. The switching mechanism 14 has the same basic configuration as in the first embodiment. However, the switching mechanism is rotated 180° in a so-called "upside-down" manner and inserted into the switch housing 12.
[0078] The spring element 24 is positioned with its edge 42 clamped between the cover portion 18 and the spacer element 44. The spacer element 44 is again clamped between the lower portion 16 and the cover portion 18 within the switch housing 12, where, according to this second embodiment, the spacer element 44 is clamped between the spring element 24 and the lower portion 16 with the insulating foil 22 interposed between them.
[0079] The spacer element 44 again has a substantially L-shaped cross-section and is provided with a support surface 50, to which the high-temperature configuration bimetal element 26 can be supported by its outer edge portion 52. The first side surface 48 of the spring element 24 also faces both the bimetal element 26 and the contact surface 34. However, the first side surface 48 of the spring element 24 here faces downward. However, according to this embodiment, the fixed contact portion 36 on which the contact surface 34 is located is no longer on the cover portion 18, but here on the lower portion 16.
[0080] However, the general switching behavior of the switching mechanism 14 remains unchanged. This is why, for the sake of brevity, the high-temperature state of the switch 10 is not shown again in the second embodiment shown in Figure 3.
[0081] Figure 4 shows a third embodiment of the switch 10 according to the present invention, where the switch 10 is basically configured similarly to the first embodiment shown in Figures 1 and 2. The spring element 24 is again clamped with its outer edge portion 42 between the spacer element 44 and the lower part 16 of the switch housing 12. However, the switching mechanism 14 is configured somewhat differently. Here, the first side surface 48 of the spring element 24 faces the bimetallic element 26 as well as the contact surface 34. However, here the bimetallic element 26 rests on a circumferential collar 62 provided on the movable contact portion 30. The spring element 24 abuts against this collar 62 from the opposite lower side. The movable contact portion 30 is not necessarily connected to the spring element 24 in a material locking manner. Instead, the spring element 24 here has a through-opening 64 in the center into which a portion of the movable contact portion 30 located below the collar 62 is inserted so as to be securely locked.
[0082] A further difference from the first embodiment shown in Figures 1 and 2 is that the fixed contact portion 36 is not located on the bottom side 38 of the cover portion 18. Instead, in the third embodiment shown in Figure 4, a contact carrier element 66 is located inside the switch housing 12, to which the fixed contact portion 36 is fixed. The contact carrier element 66 functions as a kind of sub-cover, which is clamped between the lower part 16 and the cover portion 18. More precisely, the edge 68 of the contact carrier element 66 is clamped between the cover portion 18 and the spacer element 44 with the insulating foil 22 interposed therebetween.
[0083] The contact carrier element 66 is preferably made of a conductive material, such as metal. Particularly preferably, the contact carrier element 66 has a thickness thinner than the cover portion 18 of the switch housing 12 located above it.
[0084] The main advantage of the additional contact carrier elements 66 provided herein is that they can be used in a simple design manner to compensate for manufacturing tolerances on the switch housing 12 and the switching mechanism 14. Depending on customer requirements, the contact carrier elements 66 configured as sub-covers can be pre-formed to achieve the desired contact pressure at low temperatures in the switching mechanism 14. For example, if a high level of performance is required for the switch 10 and a high contact pressure is desired between the fixed contact portion 36 and the movable contact portion 30, contact carrier elements 66 of a different shape can be inserted into the switch housing 12 than when a low level of performance is required for the switch. In other words, the switch housing 12 itself does not need to be modified for this purpose, and the contact pressure between the switching mechanism 14 and the fixed contact portion 36 can be adjusted very easily by the contact carrier elements 66. It is understood that the corresponding setting of the contact resistance between the switching mechanism 14 and the fixed contact portion 36 is also automatically achieved by setting each contact pressure. The fact that this configuration can be determined more or less solely by the shape of the contact carrier element 66 offers a significant cost advantage, because the switch can be adapted to a wide range of technical specifications without requiring any changes to the switching mechanism 14 or the switch housing 12.
[0085] A fourth embodiment of the switch 10 according to the present invention, shown in Figure 5, also follows this principle. Unlike the embodiment shown in Figure 4, here only the contact surface 34 is located directly on the bottom side of the contact carrier element 66. The extra fixed contact portion 36 is omitted.
[0086] The fifth embodiment shown in Figure 6 also follows the principle described above. However, here the contact carrier element 66 is configured as a second spring element 70, and the contact portion 36 is fixed together with its contact surface 34 positioned on it. This second spring element 70 can further increase the contact pressure between the movable contact portion 30 and the contact surface 34, thereby further decreasing the contact resistance between these two devices. The second spring element 70 applies a force to the contact portion 36 that is opposite to the force applied to the movable contact portion 30 by the first spring element 24.
[0087] Finally, with respect to the embodiments shown in Figures 4 to 6, it should be noted that the second terminal 58 of the switch is designed in a slightly different manner from that of the embodiments shown in Figures 1 to 3. This is because the terminal 58 is designed here as a recess provided in the lower part 16, into which a circumferential connecting ring 72, preferably welded to the lower part 16, can be inserted. This connecting ring 58 not only functions as an electrical connection but can also be connected to the conveyor belt during the manufacture of the switch 10.
Claims
1. A temperature-dependent switch (10), A switch housing (12) having a lower part (16) and a cover part (18) that closes the lower part (16), A temperature-dependent switching mechanism (14) is provided within a switch housing (12) and comprises a movable contact portion (30), a bimetallic element (26), and a spring element (24) that interact with the movable contact portion (30), configured to switch between a low-temperature state and a high-temperature state. In the low-temperature state, the movable contact portion (30) is pressed against a contact surface (34) located inside the switch housing (12) to establish an electrical connection between the first electrical terminal (56) and the second electrical terminal (58) of the switch (10). In the high-temperature state, the movable contact portion (30) is separated from the contact surface (34) to disconnect the electrical connection between the first electrical terminal (56) and the second electrical terminal (58). The switch housing (12) includes a spacer element (44) positioned between the lower part (16) and the cover part (18) inside the switch housing (12). At least a portion (42) of the spring element (24) is positioned between the spacer element (44) and the switch housing (12), and is fixed in a predetermined position by the interaction between the spacer element (44) and the switch housing (12). At least a portion (52) of the bimetal element (26) is positioned between the spring element (24) and the spacer element (44), and is supported on the spacer element (44) when the switching mechanism (14) is at a high temperature. A temperature-dependent switch (10) characterized in that the first side surface (48) of the spring element (24) facing the bimetallic element (26) faces the contact surface (34).
2. A temperature-dependent switch (10), A switch housing (12) having a lower part (16) and a cover part (18) that closes the lower part (16), A temperature-dependent switching mechanism (14) is provided within a switch housing (12) and comprises a movable contact portion (30), a bimetallic element (26), and a spring element (24) that interact with the movable contact portion (30), configured to switch between a low-temperature state and a high-temperature state. In the low-temperature state, the movable contact portion (30) is pressed against a contact surface (34) located inside the switch housing (12) to establish an electrical connection between the first electrical terminal (56) and the second electrical terminal (58) of the switch (10). In the high-temperature state, the movable contact portion (30) is separated from the contact surface (34) to disconnect the electrical connection between the first electrical terminal (56) and the second electrical terminal (58). The switch housing (12) includes a spacer element (44) positioned between the lower part (16) and the cover part (18) inside the switch housing (12). At least a portion (42) of the spring element (24) is positioned between the spacer element (44) and the switch housing (12), and is fixed in a predetermined position by the interaction between the spacer element (44) and the switch housing (12). At least a portion (52) of the bimetal element (26) is positioned between the spring element (24) and the spacer element (44), and is supported on the spacer element (44) when the switching mechanism (14) is at a high temperature. The temperature-dependent switch (10) is characterized in that the bimetallic element (26) has some play on the movable contact portion (30) but is constrained and held in place.
3. A temperature-dependent switch (10), A switch housing (12) having a lower part (16) and a cover part (18) that closes the lower part (16), A temperature-dependent switching mechanism (14) is provided within a switch housing (12) and comprises a movable contact portion (30), a bimetallic element (26), and a spring element (24) that interact with the movable contact portion (30), configured to switch between a low-temperature state and a high-temperature state. In the low-temperature state, the movable contact portion (30) is pressed against a contact surface (34) located inside the switch housing (12) to establish an electrical connection between the first electrical terminal (56) and the second electrical terminal (58) of the switch (10). In the high-temperature state, the movable contact portion (30) is separated from the contact surface (34) to disconnect the electrical connection between the first electrical terminal (56) and the second electrical terminal (58). The switch housing (12) includes a spacer element (44) positioned between the lower part (16) and the cover part (18) inside the switch housing (12). At least a portion (42) of the spring element (24) is positioned between the spacer element (44) and the switch housing (12), and is fixed in a predetermined position by the interaction between the spacer element (44) and the switch housing (12). At least a portion (52) of the bimetal element (26) is positioned between the spring element (24) and the spacer element (44), and is supported on the spacer element (44) when the switching mechanism (14) is at a high temperature. A temperature-dependent switch (10) characterized in that the bimetallic element (26) and the spring element (24) are each substantially disc-shaped, and the movable contact portion (30) is mounted in the center of the spring element (24).
4. A temperature-dependent switch according to any one of claims 1 to 3, wherein at least a portion (42) of the spring element (24) disposed between the spacer element (44) and the switch housing (12) includes the outer edge (40) of the spring element (24).
5. A temperature-dependent switch according to any one of claims 1 to 3, wherein at least a portion (52) of the bimetallic element (26) positioned between the spring element (24) and the spacer element (44) includes the outer edge (54) of the bimetallic element (26).
6. A temperature-dependent switch according to any one of claims 1 to 3, wherein at least a portion (42) of the spring element (24) positioned between the spacer element (44) and the switch housing (12) is (i) indirectly or directly clamped between the spacer element (44) and the lower part (16), or (ii) indirectly or directly clamped between the spacer element (44) and the cover portion (18).
7. The temperature-dependent switch according to any one of claims 1 to 3, wherein the spacer element (44) includes a spacer ring.
8. The temperature-dependent switch according to any one of claims 1 to 3, wherein the spacer element (44) has an L-shaped cross-section.
9. The temperature-dependent switch according to claim 2 or 3, wherein the first side surface (48) of the spring element (24) facing the bimetallic element (26) faces the contact surface (34).
10. The temperature-dependent switch according to claim 1, wherein the spacer element (44) protrudes from a first side surface (48) of the spring element (24) in a first direction (46), and has a support surface (50) on which at least a portion (52) of the bimetal element (26) is supported in the high-temperature state of the switching mechanism (14), and the support surface (50) is oriented laterally with respect to the first direction (46).
11. The temperature-dependent switch according to any one of claims 1 to 3, wherein the spacer element (44) is clamped within the switch housing (12) by the interaction of the lower part (16) and the cover part (18).
12. The temperature-dependent switch according to any one of claims 1 to 3, wherein the spring element (24) comprises at least one compensating portion (60) between its outer edge (54) and inner region (28), the compensating portion being configured to be radially elastic and allowing mechanical deformation of the spring element (24).
13. The temperature-dependent switch according to any one of claims 1 to 3, wherein the movable contact portion (30) is fixed to the spring element (24) by welding or soldering.
14. The temperature-dependent switch according to any one of claims 1 to 3, wherein the first electrical terminal (56) is located outside the cover portion (18), and the second electrical terminal (58) is located outside the lower portion (16).
15. The temperature-dependent switch according to any one of claims 1 to 3, wherein the lower part (16) includes a free upper edge (20) that is flanged or bent on the cover part (18).