Relay

Abstract

Provided is a relay having a simple structure and high sealability. A relay according to the present invention comprises: a cover including an internal space in which a component for exhibiting a function as a relay is accommodated, and an opening that fluidly communicates the internal space and the outside; and a low-melting-point member disposed so as to block a flow path from the opening or the internal space to the outside via the opening, and having a first melting point lower than the melting point of a material constituting the cover. The low-melting-point member is configured to melt so as to release air from the internal space of the cover through the opening when heated to a temperature exceeding the first melting point, and block the opening or the flow path when re-solidified.

Description

Relay

[0001] The present invention relates to a sealed relay.

[0002] In an electromagnetic relay (relay), the fitting portion between the main body having a contact portion and a base, etc., and the cover covering the main body, and the space between the terminal holes formed in the base and the terminals may be sealed with resin or the like to form a sealed structure.

[0003] Before its original use, a relay with a sealed structure may be exposed to a high-temperature environment where the ambient temperature exceeds 200°C, such as in a reflow process. In this case, a so-called leak may occur where the airtight structure is destroyed by the expansion pressure of the air inside the relay, leading to problems such as deterioration of product performance and entry of foreign substances from the outside. To solve such problems, conventionally, structural reinforcement has been carried out, such as increasing the adhesive strength between the adhesive and each component, or increasing the thickness of each component to increase the strength of the component itself.

[0004] In addition to structural reinforcement, techniques are also known to reduce the expansion of the air inside the relay, such as removing internal moisture by high-temperature drying and implementing a desiccant or aluminum packing. Also known is a technique of providing air holes in the relay to form an open structure to prevent the increase of internal air pressure.

[0005] Japanese Utility Model Publication No. 58-002840, Japanese Patent Application Laid-Open No. 08-321239, Japanese Patent Application Laid-Open No. 2020-140763

[0006] In the prior art, it is necessary to increase the size of the components or use special adhesives to increase the adhesive strength, or to make the components have a special structure to increase the strength. These can be factors leading to an increase in the cost of the relay and a decrease in productivity. Also, increasing the size is not preferable from the perspectives of environmental protection and SDGs because the amount of materials used increases. Furthermore, relays with an open structure having air holes have a problem that their life performance is likely to decrease when used in the range of several amperes compared to sealed relays.

[0007] Therefore, a relay with a simple structure and high sealing performance is desired.

[0008] One aspect of the present disclosure is a relay comprising: a cover having an internal space that houses components for performing a relay function, and an opening that fluidly communicates the internal space with the outside; and a low-melting-point member disposed to block a flow path from the opening or the internal space to the outside through the opening, and having a first melting point lower than the melting point of the material constituting the cover, wherein the low-melting-point member is configured to melt when heated to a temperature exceeding the first melting point, allowing air to escape from the internal space of the cover through the opening, and to block the opening or the flow path when re-solidified.

[0009] According to this disclosure, by placing a low-melting-point member in the opening of the cover or in a flow path communicating with the opening, when heated to a temperature higher than the melting point of the low-melting-point member, the low-melting-point member melts, suppressing the rise in internal pressure of the cover and preventing damage to components. Furthermore, after cooling, the low-melting-point member re-solidifies and seals the opening or flow path, resulting in a relay with high sealing performance.

[0010] This is an external perspective view of the electromagnetic relay according to the embodiment. This is an exploded perspective view of the electromagnetic relay in Figure 1. This is a cross-sectional view along the line A-A' in Figure 1. This is a cross-sectional view along the line B-B' in Figure 1. This is an enlarged view of section C in Figure 3. This is a schematic diagram showing the electromagnetic relay before heating. This is a schematic diagram showing the electromagnetic relay after heating. This is an enlarged view of section C in Figure 1. This is a perspective view showing the structure of the top surface of the cover. This is a perspective view showing the state in which the low-melting-point member is placed on the top surface of the cover. This is an exploded perspective view of the cap and the low-melting-point member. This is a perspective view showing the state in which the cap and the low-melting-point member are assembled. This is a perspective view showing the state in which the cap is placed on the cover. This is a cross-sectional view along the line E-E' in Figure 13. This is a perspective view showing another structural example of the cover. This is a cross-sectional view along the line F-F' in Figure 15. This is an enlarged view of section G in Figure 16. This is a partial cross-sectional view showing another structural example of the cover. This is a partial cross-sectional view showing yet another structural example of the cover.

[0011] Figure 1 is an external perspective view of an electromagnetic relay 10 according to an embodiment, Figure 2 is an exploded perspective view of the relay 10, and Figure 3 is a cross-sectional view of Figure 1 along line A-A'. The relay 10 is a sealed relay that, in its finished state, does not have any fluid communication parts with the outside, and comprises a cover 12, a base 14 fixed to the lower part of the cover 12, a cap 18 attached to the upper part 16 of the cover 12, and a low-melting-point member 20 disposed between the cover 12 and the cap 18. In this disclosure, the direction in which gravity acts is referred to as "down," and the opposite direction is referred to as "up." The first melting point, which is the melting point of the low-melting-point member 20, is lower than the second melting point of other components such as the cover 12 and the cap 18. Various components for performing the function of a relay, such as electromagnets, fixed contacts, movable contacts, and terminals, are arranged in the internal space 22 of the cover 12, but any components suitable for a sealed relay are acceptable, so their illustration is omitted.

[0012] Before its intended use as specified in its specifications, the relay 10 undergoes a process such as a reflow process, in which it is heated to a temperature higher than its first melting point (e.g., 200°C) but lower than its second melting point (e.g., 260°C), and then cooled to below its first melting point.

[0013] Figure 4 shows a cross-section of B-B' in Figure 1, and Figure 5 is an enlarged view of section C in Figure 3. Figures 6 and 7 schematically show the relay 10 before and after heating, respectively. When the relay 10 is heated to a temperature higher than its first melting point, the internal pressure in the internal space 22 rises as indicated by arrow 28, causing the low-melting-point member 20 to melt and liquefy. The air in the internal space 22 then flows out through the opening 24 formed at the top of the cover 12, as indicated by arrow 30, pushing the molten low-melting-point member 20 outwards from the relay 10, and then flows out to the outside of the relay 10 through the gap 26 between the cover 12 and the cap 18, as indicated by arrow 32. Thus, damage to components due to the rise in internal pressure is prevented.

[0014] Subsequently, when the relay 10 is cooled to a temperature below its first melting point, the internal pressure of the internal space 22 decreases, causing the liquefied low-melting-point member 20 to be pulled back into the internal space 22 and solidify. As a result, the gap 26 between the cover 12 and the cap 18 is sealed by the solidified low-melting-point member 20, resulting in a relay 10 with a robust sealing structure.

[0015] In this embodiment, a low-melting-point member 20 is inserted between the cover 12 and the cap 18, so that the relay 10 is in a generally sealed state in its initial condition. Subsequently, when the low-melting-point member 20 is heated to a temperature exceeding the first melting point by a high-temperature process such as reflow, the low-melting-point member 20 melts, allowing air inside the relay 10 to escape, suppressing the rise in internal pressure and preventing the destruction of the sealed structure. Furthermore, during cooling after the reflow process, the low-melting-point member 20 re-solidifies, sealing the gap between the cover 12 and the cap 18, and returning the relay to a sealed state. Therefore, by simply providing a low-melting-point member 20 between the cover 12 and the cap 18, the relay 10 can be made into a high-temperature resistant sealed relay while basically maintaining the existing structure. In addition, since the relay 10 does not require parts to increase strength, it can be made smaller and less expensive than conventional relays.

[0016] As shown in Figures 6 and 7, it is preferable that the cover 12 and cap 18 work together to create a labyrinth shape in the flow path 26 through which the molten low-melting-point member 20 and the internal space 22 flow, with localized accumulation areas 27. In this way, the molten low-melting-point member 20 re-solidifies while remaining in the accumulation areas 27 due to gravity, thereby ensuring a more reliable seal for the relay 10.

[0017] Examples of materials that make up the low-melting-point member 20 include resins with relatively low melting points (e.g., melting points of 200 to 260°C), such as polybutylene terephthalate (PBT) with a melting point of about 230°C, and engineering plastics. Such materials are suitable for the reflow process in which the relay 10 is heated to about 260°C. However, the material of the low-melting-point member 20 is not limited to these, and any material having a melting point below the temperature at which the relay 10 is heated in a predetermined process may be used. Furthermore, examples of materials that make up the cover 12 and cap 18 include liquid crystal polymers with a melting point exceeding 300°C, but are not limited to these, and any material having a melting point above the temperature at which the relay 10 is heated in a predetermined process may be used. The cover 12 and cap 18 may be made of the same material, or they may be made of different materials.

[0018] Figure 8 is an enlarged view of section D of the relay 10 in Figure 1. By forming a groove 54 in the cap 18 and a groove 40 in the cover 12, it is possible to promote the outflow of air from the internal space 22 of the cover 12 during the reflow process, as indicated by the arrow 32. A specific example will be described below.

[0019] Figure 9 is a perspective view showing the structure of the upper surface 16 of the cover 12. The upper part 16 of the cover 12 has a first recess 34 against which the cap 18 abuts, and a second recess 36 which is deeper than the first recess 34 and against which the low-melting-point member 20 abuts. The first recess 34 has a groove 40 of the same depth as the second recess 36. A protrusion 38 is formed approximately in the center of the second recess 36, defining an opening 24 that communicates with the internal space 22 of the cover 12.

[0020] Figure 10 is a perspective view showing the low-melting-point member 20 placed in the second recess 36. The low-melting-point member 20 has a substantially flat base portion 42, a frame-shaped protrusion 44 formed on the base portion 42 that fits into the protrusion 38 of the cover 12, and a ridge-shaped portion 46 formed on the base portion 42, spaced apart from the protrusion 44 in the direction of the groove 40.

[0021] Figure 11 is an exploded perspective view of the cap 18 and the low-melting-point member 20. Below the cap 18, into which the low-melting-point member 20 engages, there is a substantially rectangular recess 50 into which the frame-shaped protrusion 44 of the low-melting-point member 20 fits, a recess 52 into which the ridge-shaped portion 46 of the low-melting-point member 20 fits, and a groove 54 communicating with the recess 52. Therefore, as shown in Figure 12, when the cap 18 and the low-melting-point member 20 are engaged and then placed on the cover 12, a relay 10 is obtained in which the labyrinth-shaped flow path 26 is blocked by the low-melting-point member 20, as shown in Figure 4 or Figure 5.

[0022] Figure 13 is a perspective view showing the cap 18 positioned on the cover 12, and Figure 14 is a cross-sectional view along the line E-E' in Figure 13. In heating processes such as the reflow process described above, the internal pressure of the relay 10 increases, and an upward force F1 acts on the cap 18, which may cause the cap 18 to detach from the cover 12. Therefore, it is preferable to provide a protrusion 55 on the cap 18, while providing a recess 57 in the cover 12 into which the protrusion 55 is press-fitted. Furthermore, it is preferable to provide projections 56 on both ends of the protrusion 55 in its width direction (left-right direction in Figure 14), so that the width dimension of the protrusion 55 is slightly larger than the width dimension of the recess 57. This allows a force F2 greater than F1 and in the opposite direction to F1 to be applied to the cap 18 by press-fitting the protrusion 55 into the recess 57, thereby reliably preventing the cap 18 from coming off during the reflow process.

[0023] Figure 15 is a perspective view showing an example of the structure of a relay 10' having a cover 12' which is a modified version of cover 12. In cover 12, the opening 24 communicating with the inside of cover 12 is formed on the upper surface of cover 12, but in cover 12', an opening 68 that fluidly communicates with the internal space 22' is formed on the side 60 instead of the top.

[0024] Figure 16 is a cross-sectional view along the line F-F' in Figure 15, and Figure 17 is an enlarged view of section G in Figure 16. The cover 12' has a side wall 62 extending downward, while the base 14' fixed to the lower part of the cover 12' has two walls 64 formed to face each other at a predetermined distance from each of the sides of the side wall 62. The cover 12' and the base 14' work together to define a labyrinth-shaped flow path 69 that fluidly connects the internal space 22' and the opening 68. A low-melting-point member 66 having the same physical properties as the low-melting-point member 20 is placed at the lower part of the flow path 69.

[0025] When the relay 10' is subjected to a heating process such as a reflow process that raises the temperature above the melting point of the low-melting-point member 66, the low-melting-point member 66 melts, and the air in the internal space 22', whose internal pressure has risen, moves into the flow path 69 as indicated by arrow 70, pushing the molten low-melting-point member 66 through as indicated by arrow 72, and then flows out to the outside through the opening 68 as indicated by arrow 74, preventing an excessive rise in internal pressure in the internal space 22'. Subsequently, when the relay 10' is cooled, the molten low-melting-point member 66 solidifies in a way that blocks the flow path 69 as the internal space 22' is depressurized, resulting in a relay 10' with high sealing performance.

[0026] In relay 10', a component equivalent to the cap 18 of relay 10 is unnecessary, and its housing can be substantially composed only of the cover 12' and base 14'. Furthermore, in relay 10', the opening 68 can be provided by simply increasing the size of the side, which is particularly advantageous when there are dimensional constraints in the upper direction of the cover 12'.

[0027] Figure 18 is a partial cross-sectional view showing a structural example of a relay 10" having a cover 12'' relating to another structural example. The cover 12'' has an opening 24'' on its upper surface 16'' that fluidly communicates with the internal space 22'' of the cover 12'', similar to the cover 12''. However, the cover 12'' does not have a member corresponding to the cap 18, but instead has a flat plate-shaped member 82 that is inserted into a notch 80 formed in the cover 12'' and covers the opening 24''. Furthermore, the flat plate-shaped member 82 has an opening 84, and a low-melting-point member 86 is arranged to close the opening 84.

[0028] When the relay 10" is heated to a temperature above the melting point of the low-melting-point member 86, the low-melting-point member 86 melts, and the internal pressure of the internal space 22" of the cover 12" increases. The air inside the internal space 22" pushes away the melted low-melting-point member 86 and flows out through the opening 84, preventing an excessive increase in the internal pressure of the internal space 22". Subsequently, when the cover 12" is cooled, the melted low-melting-point member 86 solidifies to seal the opening 84 as the internal space 22" is depressurized, resulting in a highly sealed relay 10".

[0029] The material constituting the flat plate-shaped member 82 can be any material having a melting point above the heating temperature in the reflow process, etc., but from the viewpoint of efficient heat conduction to the low-melting-point member 86, metallic materials such as iron, copper, and nickel are preferred. The material constituting the low-melting-point member 86 may be a resin such as PBT, as in the embodiments described above, but it may also be a low-melting-point metal such as solder.

[0030] In the relay 10″, a component equivalent to the cap 18 of the relay 10 is unnecessary, and its housing can be substantially composed only of the cover 12″ and a base (not shown). Furthermore, in the relay 10″, by adjusting the position of the flat plate-shaped member 82 and the volume of the low-melting-point member 86, it is possible to configure it so that the low-melting-point member 86 does not protrude from the upper surface 16″ of the cover 12″ during solidification, which is advantageous when there are dimensional constraints in the direction of the upper surface of the cover 12″.

[0031] Figure 19 is a partial cross-sectional view showing a structural example of a relay 10''' having a cover 12''' according to yet another structural example. The cover 12''' has a recess 92 at its bottom 90 that is recessed downwards, and the recess 92 has an opening 94 that is fluidly in communication with the internal space 22'' of the cover 12'''. In this embodiment, downwards refers to the direction in which the substrate 88 on which the relay 10''' is mounted is located, as viewed from the relay 10'''. A low-melting-point member 96 is placed between the substrate 88 and the opening 94 so as to close the opening 94. The material constituting the low-melting-point member 96 may be a resin such as PBT, as in the above embodiment, but it may also be a low-melting-point metal such as solder.

[0032] When the relay 10'' is heated to a temperature above the melting point of the low-melting-point member 96, the low-melting-point member 96 melts, and the internal pressure of the internal space 22'' of the cover 12'' increases. The air inside the internal space 22'' pushes away the melted low-melting-point member 96 and flows out through the opening 94, preventing an excessive increase in the internal pressure of the internal space 22''. Subsequently, when the cover 12'' is cooled, the melted low-melting-point member 96 solidifies in a way that seals the opening 94 as the internal space 22'' is depressurized, resulting in a relay 10'' with high airtightness.

[0033] Preferably, a protrusion 98 is provided at a position close to the outer periphery of the recess 92 on the substrate 88, projecting toward the bottom surface 90 of the cover 12''', and cooperating with the bottom surface 90 and the substrate 88 to form a labyrinth-shaped flow path 100. In this way, excessive movement of the molten low-melting-point member 96 on the substrate 88 is prevented, and the opening 94 can be reliably closed when the low-melting-point member 96 solidifies.

[0034] In relay 10'', a component equivalent to the cap 18 of relay 10 is not required. Furthermore, in relay 10'', gas is released from the bottom surface of cover 12'' when the internal pressure rises due to heating in the internal space 22'', so there is no need to increase the size of the top or sides of cover 12'', which is particularly advantageous when dimensional constraints are severe.

[0035] 10, 10′, 10″, 10″′ Relay, 12, 12′, 12″, 12″′ Cover, 14, 14′ Base, 18 Cap, 20, 66, 86, 96 Low melting point member, 22, 22′, 22″, 22″′ Internal space, 24, 24″, 68, 84, 94 Opening, 26, 69, 100 Flow path, 34, 36, 50, 52, 57, 92 Recess, 40, 54 Groove, 38, 44, 55, 98 Protrusion, 46 Ridged part, 56 Projection, 60 Side part, 62 Side wall, 64 Wall, 82 Plate-shaped member, 90 Bottom

Claims

1. A relay comprising: an internal space containing components for performing a relay function, and a cover having an opening that fluidly communicates the internal space with the outside; and a low-melting-point member disposed to block a flow path from the opening or the internal space to the outside through the opening, and having a first melting point lower than the melting point of the material constituting the cover, wherein the low-melting-point member is configured to melt when heated to a temperature exceeding the first melting point, allowing air to escape from the internal space of the cover through the opening, and to block the opening or the flow path when re-solidified.

2. The relay according to claim 1, further comprising a cap attached to the upper surface of the cover and cooperating with the cover to define the labyrinth-shaped flow path, wherein the opening is formed on the upper surface of the cover and the low-melting-point member is disposed between the cover and the cap.

3. The relay according to claim 2, wherein the cap has a width dimension greater than the recess formed in the cover and has a protrusion that is press-fitted into the recess.

4. The relay according to claim 1, further comprising a base fixed to the lower part of the cover, the opening being formed on the side of the cover, the cover having a side wall extending downward, the base having two walls formed to face each other at a predetermined distance from each of the sides of the side wall, the cover and the base working together to define a labyrinth-shaped flow path that fluidly communicates the internal space of the cover and the opening, and the low-melting-point member being disposed within the flow path.

5. The relay according to claim 1, wherein a flat plate-shaped member having the opening is provided on the upper part of the cover, and the low-melting-point member is arranged to close the opening.

6. The relay according to claim 1, wherein the lower part of the cover has a recess with the opening, and the low-melting-point member is arranged between the substrate to which the relay is mounted and the recess so as to close the opening.

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