relay

Abstract

To provide a relay with a simple structure and high sealing performance. [Solution] The relay 10 comprises a cover 12 having an internal space 22 in which components for performing the function of a relay are housed, and an opening 24 that fluidly communicates the internal space 22 with the outside, and a low-melting-point member 20 that is arranged to block the opening 24 or a flow path 26 from the internal space 22 to the outside through the opening 24, and has a first melting point lower than the melting point of the material constituting the cover 12, wherein the low-melting-point member 20 is configured to melt when heated to a temperature exceeding the first melting point, allowing air to escape from the internal space 22 of the cover 12 through the opening 24, and to block the opening 24 or the flow path 26 when it re-solidifies.

Description

Technical Field

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

Background Art

[0002] In an electromagnetic relay, the fitting part between the main body having a contact part and a base, etc., and the cover covering the main body, and the space between the terminal hole formed in the base and the terminal may be sealed with resin or the like to form a sealed structure. [[ID=X]] [[ID=X]]

[0003] [[ID=X]] Before the 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 external foreign matter. 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. [[ID=X]] [[ID=X]]

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

Prior Art Documents

Patent Documents

[0005] [[ID=X]] [[ID=X]]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] Conventional technologies require increasing the size of components or using special adhesives to improve adhesive strength, or creating special component structures to enhance strength. These factors can lead to increased relay costs and decreased productivity. Furthermore, increasing the size of components increases the amount of material used, which is undesirable from the perspective of environmental protection and SDGs. In addition, open-structure relays with air holes have the drawback of having a shorter lifespan compared to sealed relays when used in the several-ampere range.

[0007] Therefore, a relay with a simple structure and high airtightness is desired. [Means for solving the problem]

[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. [Effects of the Invention]

[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. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view of the external appearance of an electromagnetic relay according to an embodiment. [Figure 2]It is an exploded perspective view of the electromagnetic relay in FIG. 1. [Figure 3] It is a cross-sectional view taken along the line A-A' in FIG. 1. [Figure 4] It is a cross-sectional view taken along the line B-B' in FIG. 1. [Figure 5] It is an enlarged view of part C in FIG. 3. [Figure 6] It is a diagram schematically showing the electromagnetic relay before heating. [Figure 7] It is a diagram schematically showing the electromagnetic relay after heating. [Figure 8] It is an enlarged view of part C in FIG. 1. [Figure 9] It is a perspective view showing the structure of the upper surface of the cover. [Figure 10] It is a perspective view showing the state where a low-melting-point member is arranged on the upper surface of the cover. [Figure 11] It is an exploded perspective view of the cap and the low-melting-point member. [Figure 12] It is a perspective view showing the state where the cap and the low-melting-point member are assembled. [Figure 13] It is a perspective view showing the state where the cap is arranged on the cover. [Figure 14] It is a cross-sectional view taken along the line E-E' in FIG. 13. [Figure 15] It is a perspective view showing another structural example of the cover. [Figure 16] It is a cross-sectional view taken along the line F-F' in FIG. 15. [Figure 17] It is an enlarged view of part G in FIG. 16. [Figure 18] It is a partial cross-sectional view showing another structural example of the cover. [Figure 19] It is a partial cross-sectional view showing yet another structural example of the cover.

Embodiments for Carrying Out the Invention

[0011] FIG. 1 is an external perspective view of an electromagnetic relay (relay) 10 according to an embodiment, FIG. 2 is an exploded perspective view of the relay 10, and FIG. 3 is a view showing the A-A' cross section of FIG. 1. The relay 10 is a relay with a sealed structure that has no fluid communication part with the outside in the state of a finished product, and includes 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 the present 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 members such as the cover 12 and the cap 18. In the internal space 22 of the cover 12, various components for exerting the function as a relay, such as an electromagnet, a fixed contact, a movable contact, and a terminal, are arranged, but any components may be used as long as they are for a hermetic relay, and thus the illustration is omitted.

[0012] Before the original use defined by the specifications and the like of the relay 10, it is heated to a temperature (for example, 260°C) that is higher than the first melting point (for example, 200°C) but lower than the second melting point, such as in a reflow process, and then cooled to below the first melting point.

[0013] FIG. 4 is a view showing the B-B' cross section of FIG. 1, and FIG. 5 is an enlarged view of part C in FIG. 3. FIGS. 6 and 7 are diagrams schematically showing the relay 10 before and after heating, respectively. When the relay 10 is heated to a temperature higher than the first melting point, the internal pressure in the internal space 22 rises as indicated by the arrow 28, and the low melting point member 20 melts and liquefies. Then, the air in the internal space 22 flows out from the opening 24 formed in the upper part of the cover 12 as indicated by the arrow 30, and while pushing the melted low melting point member 20 outward of the relay 10, it flows out of the relay 10 from the gap 26 between the cover 12 and the cap 18 as indicated by the arrow 32. Therefore, damage to components due to the increase 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 state. 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 of 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 200-260°C), such as polybutylene terephthalate (PBT) with a melting point of approximately 230°C, and engineering plastics. Such materials are suitable for the reflow process in which the relay 10 is heated to approximately 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 processes such as reflow, as indicated by the arrow 32. A specific example is 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 EE' line 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 FF' line 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 to block the flow path 69 as the internal space 22' is depressurized, resulting in a highly sealed relay 10'.

[0026] In relay 10', a component equivalent to the cap 18 of relay 10 is unnecessary, and its housing can be constructed substantially with only 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, like the cover 12, is in fluid communication with the internal space 22″ of 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 positioned 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 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 component 82 and the volume of the low-melting-point component 86, it is possible to configure it so that the low-melting-point component 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''' relating 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 highly sealed relay 10''.

[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, 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. [Explanation of symbols]

[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 openings, 26,69,100 flow paths, 34, 36, 50, 52, 57, 92 recesses, 40, 54 grooves, 38, 44, 55, 98 Convex part, 46 Ridged part, 56 Projection, 60 Side part, 62 Side wall, 64 Wall, 82 Plate-shaped member, 90 Bottom

Claims

1. A cover having an internal space that houses components for performing the function of a relay, and an opening that fluidly communicates the internal space with the outside, The cover comprises a low-melting-point member having a first melting point lower than the melting point of the material constituting the cover, which is arranged to block the flow path from the opening or the internal space to the outside through the opening, The relay is configured such that when the low-melting-point member is heated to a temperature exceeding the first melting point, it melts to allow air to escape from the internal space of the cover through the opening, and when it resolidifies, it closes the opening or the flow path.

2. The present invention further comprises a cap attached to the upper surface of the cover, which cooperates with the cover to define the labyrinth-shaped flow path, The relay according to claim 1, 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 larger than the recess formed in the cover and has a protrusion that is press-fitted into the recess.

4. It further has a base that is fixed to the lower part of the cover, The aforementioned opening is formed on the side of the cover, The cover has a side wall extending downward, and the base has 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 cooperate to define a labyrinth-shaped flow path that fluidly connects the internal space of the cover and the opening. The relay according to claim 1, wherein the low-melting-point member is arranged in the flow path.

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

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

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