Switching device

Abstract

Switching device (1) comprising at least one movable contact (2) and at least one fixed contact (3), a bimetallic element (4) and a stop element (5), wherein the bimetallic element (4) is configured to deform thermally by an electric current and trigger the switching device (1) so that the fixed (2) and the movable contact (3) are separated when the bimetallic element (4) reaches a predetermined deformation. In a deformed state (41) in which the bimetallic element (4) has the predetermined deformation, the bimetallic element (4) is in contact with the stop element (5). The stop element (5) is configured to dissipate heat from the bimetallic element (4).

Description

[0001] The present disclosure relates to a switching device. The switching device can be a circuit breaker.

[0002] One of the tasks to be solved is, among other things, to specify an improved switching device with, in particular, a reduced thermal load on a bimetallic element of the switching device.

[0003] This objective is achieved, inter alia, by a switching device comprising the features of independent claim 1. Advantageous embodiments and further developments are the subject of dependent claims.

[0004] In at least one embodiment, the switching device comprises at least one movable contact and at least one fixed contact, a bimetallic element, and a stop element. The bimetallic element is configured to deform thermally due to an electric current flow and trigger the switching device, such that the fixed and movable contacts are separated when the bimetallic element reaches a predetermined deformation. In a deformed state where the bimetallic element exhibits the predetermined deformation, the bimetallic element is in contact with the stop element. The stop element is configured to dissipate heat from the bimetallic element.

[0005] In particular, the switching device is designed to be integrable into an electrical system.

[0006] For example, the fixed and movable contacts are arranged in a power line of the electrical system. Thus, the power line can be closed or opened by the switching device.

[0007] A current flowing in the electrical conductor can heat the bimetallic element. It is possible for the current to flow directly through the bimetallic element. Due to the heating caused by the current, the bimetallic element deforms during operation. If the bimetallic element reaches a predetermined deformation, for example, in response to the current exceeding a predefined threshold, it can activate a tripping mechanism of the switching device, which opens the fixed and movable contacts, thus interrupting the electrical circuit. This allows an overcurrent through the bimetallic element to be detected and the electrical circuit to be interrupted in a safety-critical situation. Specifically, the switching device is a circuit breaker or part of a circuit breaker.

[0008] The bimetallic element is preferably a metal sheet. The bimetallic element further preferably comprises at least two different materials with different coefficients of thermal expansion. These materials are, for example, metal alloys such as steel alloys, which differ particularly in their material composition. The different materials can form layers of the bimetallic element, each layer preferably having the same outer contour as the entire bimetallic element.

[0009] The different materials of the bimetallic element expand thermally in response to the electric current. Because the thermal expansion of the materials in the bimetallic element differs, the bimetallic element deforms. For example, the bimetallic element bends in one direction.

[0010] In particular, when the bimetallic element reaches the deformed state, it comes into contact with the stop element. The stop element preferably comprises a material with a comparatively high thermal conductivity. For example, the stop element comprises at least one metal such as copper or steel. Preferably, the thermal conductivity of the stop element is at least 300 W / (mK), at least 350 W / (mK), or at least 400 W / (mK). This means, in particular, that heat can be efficiently dissipated from the bimetallic element by the stop element.

[0011] Due to the efficient heat dissipation from the bimetallic element by the stop element, the bimetallic element can return to its initial state relatively quickly. In this initial state, the bimetallic element is either undeformed or substantially undeformed. Therefore, the switching device can be reset in a shorter time compared to conventional switching devices where the bimetallic element is primarily cooled by air, which has a significantly lower thermal conductivity coefficient of approximately 0.026 W / (mK). This allows the switching element to meet international standards for circuit breakers even after a relatively long operating time.

[0012] Furthermore, the stop element serves primarily as a limiter for the deformation of the bimetallic element. In other words, the stop element is specifically designed to limit or stop the deformation of the bimetallic element. This means, in particular, that the bimetallic element deforms within a defined area inside the circuit breaker housing between its initial state and the stop element. This significantly reduces the risk of the bimetallic element contacting internal boundaries of the housing, which would cause irreversible or plastic deformation of the bimetallic element. Such plastic deformation can damage the bimetallic element and thus the switching device, leading to an undesirable increase in switching times.

[0013] Another advantage of limiting the deformation of the bimetallic element is that it prevents plastic deformation under high thermal stress. This also significantly reduces the risk of damage to the bimetallic element.

[0014] According to at least one embodiment of the switching device, at least 50%, or preferably 75%, or more preferably 90%, or more preferably substantially 100% of the surface of the stop element facing the bimetallic element is in contact with, or in direct contact with, the bimetallic element in its deformed state. Advantageously, the surface of the stop element facing the bimetallic element can form a particularly large cooling surface. This enables efficient heat dissipation from the bimetallic element.

[0015] Additionally or alternatively, at least 30%, preferably at least 50%, or more preferably at least 70%, or more preferably at least 90% of a surface of the bimetallic element facing the stop element is in contact with, or in direct contact with, the stop element in the deformed state. The bimetallic element can, for example, have a rectangular shape. It is also possible for the bimetallic element to have any geometric shape, for example, adapted to the application of the switching device.

[0016] According to at least one embodiment of the switching device, the bimetallic element in its deformed state comprises a first radius of curvature. For example, the bimetallic element bends in its deformed state. In particular, the surface of the bimetallic element facing the stop element comprises the first radius of curvature. Preferably, the stop element comprises a second radius of curvature corresponding to the first radius of curvature. In particular, a surface of the stop element facing the bimetallic element comprises the second radius of curvature. By matching the radii of curvature of the bimetallic element and the stop element, a particularly large contact area between the bimetallic element in its deformed state and the stop element is possible. This allows for efficient heat dissipation from the bimetallic element.

[0017] According to at least one embodiment of the switching element, the contact area between the bimetallic element in the deformed state and the stop element is at least 100 mm². 2 or preferably at least 150 mm 2 or preferably at least 200 mm 2 In particular, the size of the contact area depends on the application of the switching device. The contact area values ​​mentioned above, for example, refer to an application where the switching device is used as a miniature circuit breaker. With such a comparatively large contact area, efficient heat dissipation from the bimetallic element can be achieved.

[0018] According to at least one embodiment, the switching device comprises a release unit configured to trigger the switching device. Furthermore, the switching device comprises a release slide connected to the release unit and movable relative to it. In particular, the release slide is configured to be moved relative to the release unit by the bimetallic element in its deformed state. The release slide is specifically configured to activate the release unit in its deformed state.

[0019] For example, the release slide is mechanically connected to the bimetallic element, so that when the bimetallic element is deformed, the release slide is moved relative to the release unit. For example, the release slide is pulled out of the release unit. In the deformed state, the release slide may have moved relative to the release unit beyond a threshold value, causing the release unit to trigger the switching device. Preferably, the movable and fixed contacts of the switching device are separated by activating the release unit and triggering the switching device.

[0020] According to at least one embodiment of the switching device, which includes a release unit, the switching device comprises two switching states, wherein in a first switching state the movable contact is in electrical contact with the fixed contact and in the second switching state the movable contact is separated from the fixed contact. This means, in particular, that in the first switching state the switching device is "closed" and in the second switching state the switching device is "open".

[0021] In particular, the trigger unit is designed to change the switching state of the switching device.

[0022] For example, the release unit is designed to switch the switching device from the first switching state to the second switching state when the bimetallic element is in a deformed state or is moved into this state. This means, in particular, that if the bimetallic element is deformed, for example, due to an overcurrent that heats the bimetallic element, to the point where it reaches the predetermined deformation, the release unit opens the switching device and interrupts the current path in which the switching device may be located.

[0023] The release unit can further be configured to allow the switching device to be switched from the second switching state to the first switching state when the bimetallic element is in its initial state. For example, the release unit can include a hand lever with which the switching device can be closed or reset by a user. Preferably, the hand lever can only be actuated when the bimetallic element is in its initial state or substantially in its initial state.

[0024] Preferably, the stop element is separate from the release unit, the movable contact, and / or the fixed contact. For example, the stop element remains unchanged when the switching device switches from the first switching state to the second switching state or vice versa. This means, in particular, that the stop element does not change its position or the like when the switching device is released.

[0025] For example, the bimetallic element can be configured to reach the deformed state from its initial state within 3 minutes or less. Specifically, the bimetallic element is used in a switching device configured for use in an electrical system with a maximum operating current of 20 A. In this case, the switching device can be a miniature circuit breaker. For electrical systems with a higher maximum operating current, the bimetallic element can be configured to reach the deformed state from its initial state over a longer period. Thus, the bimetallic element is configured to activate the trip unit and switch the device relatively quickly in an overcurrent situation.

[0026] Furthermore, the bimetallic element is designed, for example, to return to its initial state from a deformed state within 3 minutes or less. In particular, the bimetallic element is used in a switching device designed for use in an electrical system with a maximum operating current of 20 A. For electrical systems with a higher maximum operating current, the bimetallic element can be configured to return to its initial state from a deformed state over a longer period. Therefore, once the overcurrent situation is resolved, the switching device can be reset or closed after a relatively short time.

[0027] According to at least one embodiment, the switching device includes a shunt. The shunt is in contact with the bimetallic element. The shunt is configured to heat the bimetallic element when a current threshold of the electrical system into which the switching device is integrated is exceeded. This means, in particular, that in an overcurrent situation, the bimetallic element is heated by the shunt. Advantageously, it is not necessary to allow current to flow through the bimetallic element by using a shunt.

[0028] According to at least one embodiment of the switching device, the stop element comprises a solid metal block. "Solid metal block" here means, in particular, that the stop element is formed entirely from a single piece of metal. A solid metal block can advantageously absorb a particularly large amount of heat from the bimetallic element. Thus, efficient heat dissipation can be achieved.

[0029] According to at least one embodiment, the switching device comprises a housing in which at least the bimetallic element and the stop element are arranged. It is also possible that the release unit, the release slide, and preferably the fixed and movable contacts are arranged in the housing.

[0030] In particular, the bimetallic element is spaced apart from the housing in its deformed state. Preferably, the bimetallic element is also spaced apart from the housing in its initial state and in all intermediate states between the initial state and the deformed state. In other words, the bimetallic element does not touch the housing during normal operation of the switching device. This reduces the risk of plastic deformation of the bimetallic element due to contact with the inner walls of the housing when the bimetallic element is deformed.

[0031] According to at least one embodiment, the switching device is a circuit breaker or part of a circuit breaker. For example, the switching device is used as a circuit breaker.

[0032] The circuit breaker is preferably a miniature circuit breaker. It can be used in domestic applications, such as in a household, or in industrial applications, such as motor control.

[0033] Further advantages and advantageous embodiments, as well as further developments of the switching device described here, will become clear with reference to the following exemplary embodiments in conjunction with schematic drawings. Identical elements, elements of the same type, or elements with the same effect are designated with the same reference numerals in the figures. The figures and the dimensions of the elements shown in the figures are not to scale. Rather, individual elements may be exaggerated to improve clarity and / or comprehensibility.

[0034] In the characters: Fig. Figure 1 shows a schematic representation of a switching device described here according to an embodiment in a first state; Fig. Figure 2 shows a schematic representation of a switching device described here according to the exemplary embodiment in a second state; Fig. Figure 3 shows a detailed view of the switching device described here according to the exemplary embodiment.

[0035] Fig. Figure 1 illustrates a switching device 1 described here according to a first embodiment in a first state 11. Fig. Figure 2 illustrates the switching device 1 according to the first embodiment in a second state 12.

[0036] The switching device 1 comprises a bimetallic element 4. The bimetallic element 4 is a bimetallic strip comprising at least two layers of different materials. The different materials have different coefficients of thermal expansion, so that the bimetallic element 4 deforms when heated.

[0037] The switching device 1 further comprises a stop element 5. The stop element 5 comprises a solid metal block, for example made of steel and / or copper. The stop element 5 has a thermal conductivity coefficient of at least 350 W / (mK).

[0038] The switching device 1 comprises a release unit 7, which is configured to switch the switching device 1 by moving a movable contact 2. In the first switching state 11, the movable contact 2 is in electrical contact with a fixed contact 3. In the second switching state 12, the movable contact 2 and the fixed contact 3 are separated from each other.

[0039] The switching device 1 is integrated into an electrical system 100 and is configured to open or close a power line of the electrical system. For example, the switching device 1 is a miniature circuit breaker or part of a miniature circuit breaker.

[0040] During operation of the switching device 1, the switching device 1 may be in its initial switching state 11, and the bimetallic element 4 may be in an initial state 42. If a current in the electrical system 100 exceeds a predetermined threshold, for example, 105% of a specified operating current, a shunt 9 connected to the bimetallic element 4 heats the bimetallic element 4. In such an overcurrent situation, the bimetallic element 4 deforms and bends. The bimetallic element 4 deforms to a predetermined degree of deformation. In other words, the bimetallic element 4 reaches a deformed state 41.

[0041] In the deformed state 41, the bimetallic element 4 moves a release slide 8 relative to the release unit 7. In the initial state 42, the release slide 8 is in a first state 81 ( Fig. 1) The release slide 8 is pulled out of the release unit 7 and reaches a second state 82 ( Fig. 2) Moving the release slide 8 from the first state 81 to the second state 82 causes the release unit 7 to switch the switching device 1 by opening the movable and fixed contacts 2, 3. Thus, an overcurrent situation and a potentially safety-relevant situation in the electrical system 100 can be detected by means of the bimetallic element 4, and the switching device 1 can interrupt the current flow of the electrical system 100.

[0042] In the deformed state 41, the bimetallic element 4 is in direct contact with the stop element 5. The stop element 5 is designed to both terminate the deformation of the bimetallic element 4 and dissipate heat from it. This significantly reduces the risk of damage to the bimetallic element 4, for example, due to plastic deformation or overheating. Since the stop element 5 is a solid metal block with high thermal conductivity, efficient heat dissipation is achieved.

[0043] In particular, due to heat dissipation from the bimetallic element 4, the bimetallic element 4 is spaced away from a housing 10 of the switching device 1 in the deformed state 41. The bimetallic element 4 is also spaced away from the housing 10 in the initial state 42 and all intermediate states between the initial state 42 and the deformed state 41.

[0044] In the deformed state 41, the bimetallic element 4 has a first radius of curvature 40. In particular, a surface of the bimetallic element 4 facing the stop element 5 has the first radius of curvature 40. A surface of the stop element 5 facing the bimetallic element 4 has a second radius of curvature 50. The first and second radii of curvature 40 and 50 correspond to each other.

[0045] The coordinated first and second radii of curvature 40, 50 allow for a particularly large contact area of ​​more than 100 mm between the bimetallic element 4 in the deformed state 41 and the stop element 5. 2 This can be achieved. For example, the first and second radii of curvature are approximately 40 and 50 mm respectively, which is about 170 mm, and the contact area is approximately 100 mm². 2 .

[0046] Due to the efficient heat dissipation from the bimetallic element 4, the relaxation time of the bimetallic element 4 can be less than 3 minutes. The relaxation time indicates the period of time that the bimetallic element 4 requires to return from the deformed state 41 to the initial state 42.

[0047] In particular, once the overcurrent situation in the electrical system 100 has been resolved, the switching device 1 can be reset to the first state 11. For example, the release unit 7 includes a hand lever for manually resetting the switching device 1 (not shown).

[0048] The switching device 1 is resettable, in particular, when the bimetallic element 4 is relaxed in the initial state 41. The switching device 1 can be reset after a particularly short time, since the relaxation time is advantageously small.

[0049] Fig. Figure 3 shows a detailed view of the switching device 1 of the Fig. 1 and Fig. 2. In Fig. Figure 3 shows that in the present embodiment, the bimetallic element 4 has a U-shape, with the stop element 5 arranged such that it is in contact with one leg of the U-shaped bimetallic element 4. The shape of the bimetallic element 4 is not limited to a U-shape. In other embodiments, the bimetallic element 4 can have essentially any shape, for example, a rectangular shape, without restricting other features of the switching device 1.

[0050] It is also possible that the stop element 5 is arranged on both legs of the U-shaped bimetallic element 4 without restricting other features of the switching device 1.

[0051] The invention is not limited to the embodiments described with reference to the embodiments. Rather, the invention encompasses any new feature and also any combination of features, which in particular includes any combination of features of the claims and any combination of features of the embodiments, even if this feature or this combination itself is not expressly specified in the claims or embodiments. References 1 switching device 2 movable contacts 3 fixed contact 4 Bimetallic element 5 Stop element 7 Trigger unit 8 release slides 81 first position of the trigger slide 82 second state of the trigger slide 9 Shunt 10 cases 11 first switching state 12 second switching state 40 first radius of curvature 41 deformed condition 42 Initial state 50 second radius of curvature 100 electrical system

Claims

[1] Switching device (1) comprising at least one movable contact (2), at least one fixed contact (3), a bimetallic element (4) and a stop element (5), wherein the bimetallic element (2) is configured to thermally deform itself by a current and to trigger the switching device (1) so that the fixed and movable contacts (2, 3) are separated when the bimetallic element (4) reaches a predetermined deformation, in a deformed state (41) in which the bimetallic element (4) has the predetermined deformation, the bimetallic element (4) is in contact with the stop element (5) and the stop element (5) is configured to dissipate heat from the bimetallic element (4). [2] Switching device (1) according to claim 1, wherein at least 50% of a surface of the stop element (5) facing the bimetallic element (4) is in contact with the bimetallic element (4) in the deformed state (41). [3] Switching device (1) according to claim 1 or 2, wherein the bimetallic element (4) in the deformed state (41) has a first radius of curvature (40) and the stop element (5) has a second radius of curvature (50) corresponding to the first radius of curvature (40). [4] Switching device (1) according to one of the preceding claims, wherein a contact area between the bimetallic element (4) in the deformed state (41) and the stop element (5) is at least 100 mm² 2 amounts. [5] Switching device (1) according to one of the preceding claims, further comprising a release unit (7) configured to release the switching device (1) and a release slide (8) connected to the release unit (7) and movable relative to the release unit (1), wherein the release slide (8) is designed to be movable by the bimetallic element (4) in the deformed state (41), and wherein the release slide (8) is configured to activate the release unit (1) in the deformed state (41). [6] Switching device (1) according to claim 5, wherein the switching device (1) comprises two switching states (11, 12), wherein in a first switching state (11) the movable contact (2) is in electrical contact with the fixed contact (3) and in the second switching state (12) the movable contact (2) is separated from the fixed contact (3), wherein the release unit (7) is configured to change the switching state (11, 12) of the switching device (1). [7] Switching device (1) according to claim 6, wherein the release unit (7) is configured to switch the switching device (1) from the first switching state (11) to the second switching state (12) when the bimetallic element (4) is in the deformed state (41), and wherein the release unit (7) is configured to enable switching the switching device (1) from the second switching state (12) to the first switching state (11) when the bimetallic element (4) is in an initial state (42). [8] Switching device (1) according to claim 7, wherein the bimetallic element (4) is configured to reach the deformed state (41) from the initial state (42) within 3 minutes or less. [9] Switching device (1) according to claim 7 or 8, wherein the bimetallic element (4) is configured to reach the initial state (42) from the deformed state (41) in 3 minutes or less. [10] Switching device (1) according to one of the preceding claims, further comprising a shunt (9) which is in contact with the bimetallic element (4), wherein the shunt (9) is configured to heat the bimetallic element (4) when a current threshold of an electrical system (100) in which the switching device (1) is included is exceeded. [11] Switching device (1) according to one of the preceding claims, wherein the stop element (5) comprises a solid metal block. [12] Switching device (1) according to one of the preceding claims, further comprising a housing (10) in which at least the bimetallic element (4) and the stop element (5) are arranged, wherein the bimetallic element (4) is spaced apart from the housing (10) in the deformed state (41). [13] Switching device (1) according to one of the preceding claims, wherein the switching device (1) is a miniature circuit breaker.

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