Arc constraint mechanism

Abstract

In a contact switch, an arc generated between two contacts is handled. An arc restraint mechanism (100) includes: a first contact (111) and a second contact (121), both of which can be brought into contact and separated; and an arc restraint portion (130), which is electrically insulated from a circuit including the first contact and the second contact, is substantially annular and includes a magnetic body, has an axis parallel to the direction of a gap between the first contact and the second contact when the first contact and the second contact are in a non-contact state, and is provided so as to surround the gap.

Description

Technical Field

[0001] The present invention relates to an arc containment mechanism. Background Art

[0002] Patent document 1 describes a latch-type relay comprising: a yoke wound with an energized coil and having a built-in magnet; a working piece that moves between an open position and a closed position when attracted and released by one end of the yoke by switching the energization to the energized coil; and a control contact that makes a movable contact that receives the movement of the working piece contact and separate from a fixed contact to connect and disconnect the current. When the working piece is moved to the open position to disconnect the control contact to block the current, a part of the magnetic flux generated by the energized coil on the yoke is superimposed on the magnetic flux of the magnet and guided to the control contact side as leakage magnetic flux, thereby stretching the arc generated between the movable contact and the fixed contact to the side end of the leaf spring and extinguishing the arc. The fixed contact is provided on a first fixed terminal having a screen-like main body. The movable contact is provided on a leaf spring that is pressed by the movement of the operating piece to contact the fixed contact, and the upper end of the leaf spring is connected to the second fixed terminal. The second fixed terminal has a first circuit-forming portion that extends upward and forms a circuit parallel to the longitudinal direction of the leaf spring. The gap between the first circuit-forming portion and the screen-like main body of the first fixed terminal is smaller than the gap between the leaf spring and the screen-like main body of the first fixed terminal.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-196362 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] In a switch with contacts, an arc generated between two contacts may damage components around the contacts. An object of the present invention is to address this arcing.

[0008] Solutions for solving problems

[0009] In order to achieve the above-mentioned purpose, the arc restraint mechanism involved in the present invention comprises: a first contact and a second contact, both of which can contact and separate; and an arc restraint portion, which is electrically insulated from the circuit including the first contact and the second contact, is roughly annular including a magnetic body, and has an axis parallel to the direction of the gap between the first contact and the second contact when the first contact and the second contact are in a non-contact state, and is arranged in a manner to surround the gap.

[0010] Effects of the Invention

[0011] According to the present invention, in a contact switch, it is possible to cope with an arc generated between two contacts. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is an explanatory diagram showing a closed circuit state of the arc confinement mechanism according to the first embodiment.

[0013] Figure 2 This is an explanatory diagram showing the arc confinement mechanism according to the first embodiment, omitting the movable plate and the movable contact.

[0014] Figure 3 It is an explanatory diagram showing the open state of the arc restraining mechanism according to the first embodiment.

[0015] Figure 4 It is an explanatory diagram showing a magnetic field generated by a linear current.

[0016] Figure 5 It is an explanatory diagram showing an arc confinement mechanism according to the second embodiment.

[0017] Figure 6 It is an explanatory diagram showing a closed circuit state of the arc confinement mechanism according to the third embodiment.

[0018] Figure 7 It is an explanatory diagram showing an open state of the arc restraining mechanism according to the third embodiment.

[0019] Figure 8 It is an explanatory diagram showing a closed circuit state of the arc confinement mechanism according to the fourth embodiment.

[0020] Figure 9 This is an explanatory diagram showing the arc confinement mechanism according to the fourth embodiment, omitting the movable plate and the movable contact.

[0021] Figure 10 It is an explanatory diagram showing an open state of the arc restraining mechanism according to the fourth embodiment.

[0022] Figure 111 is an explanatory diagram showing a closed circuit state of an arc restraining mechanism according to a fifth embodiment.

[0023] Figure 12 It is an explanatory diagram showing an open state of the arc restraining mechanism according to the fifth embodiment.

[0024] Figure 13 It is an explanatory diagram of the arc confinement mechanism according to the sixth embodiment.

[0025] Figure 14 1 is a plan view showing the interior of the thermal protector in a closed circuit state.

[0026] Figure 15 yes Figure 14 JJ line cross-section diagram.

[0027] Figure 16 It is a cross-sectional view of the thermal protector in the open circuit state. DETAILED DESCRIPTION

[0028] Hereinafter, the present invention will be described based on the illustrated embodiments. However, the present invention is not limited to the embodiments described below.

[0029] [First embodiment]

[0030] exist Figures 1 to 3 Schematic diagram of an arc confinement mechanism 100 according to this embodiment. Figure 1 (a) is a top view of the arc restraint mechanism 100 in the switch closed state (state where two contacts are in contact), Figure 1 (b) is Figure 1 (a) AA line cross-sectional view. Figure 2 (a) is a top view of the arc restraint mechanism 100, omitting the illustration of the movable plate 120 and the movable contact 121 described later. Figure 2 (b) is Figure 2 BB line cross-sectional view of (a). Figure 3 1 is a cross-sectional view of the arc restraint mechanism 100 in the switch-off state (state where two contacts are not in contact).

[0031] The arc restraint mechanism 100 includes: a fixed contact 111, which is mounted on the surface of a substrate 110; and a movable contact 121, which is mounted on a movable plate 120 arranged opposite to the substrate 110 and can contact and separate from the fixed contact 111. A driving mechanism (not shown) for moving the movable plate 120 is provided on the movable plate 120. Examples of the driving mechanism include bimetallic elements and electromagnets. The fixed contact 111 and the movable contact 121 are components of a contact switch and are electrically connected to an electrical machine such as a motor (not shown).

[0032] The arc confinement mechanism 100 further includes a generally annular arc confinement portion 130 formed of a magnetic material. Arc confinement portion 130 is supported on the surface of substrate 110 by a support portion 112 spaced apart from fixed contact 111. Fixed contact 111 is positioned outside hollow portion 131 of arc confinement portion 130, regardless of whether the switch is open or closed. Movable contact 121 is at least partially positioned within hollow portion 131 when the switch is closed, and outside hollow portion 131 when the switch is open.

[0033] The arc restricting portion 130 is provided at a position corresponding to the gap g1 between the fixed contact 111 and the movable contact 121 in the switch OFF state. Specifically, the arc restricting portion 130 is arranged so that its axis AX is parallel to the direction of the gap g1 and surrounds the gap g1.

[0034] Arc confinement portion 130 is electrically insulated from the electrical circuit including fixed contact 111 and movable contact 121. Furthermore, arc confinement portion 130 is positioned so as not to come into contact with movable plate 120 or movable contact 121. The positional relationship is set such that, in the OFF state (open stable state), the sum of distance d1 between arc confinement portion 130 and fixed contact 111 and distance d2 between arc confinement portion 130 and movable contact 121 is greater than gap g1. Specifically, this is expressed as follows:

[0035] d1+d2>g1 (1)

[0036] The distances d1 and d2 are both spatial distances serving as insulation distances.

[0037] According to this embodiment, the arc generated between the two contacts when the switch is switched from one of the closed state and the open state to the other state is confined inside the arc confinement portion 130 which is magnetized by the magnetic field generated by the arc. Figure 4 , while explaining this point.

[0038] like Figure 4 As shown, a magnetic field Ba is generally generated around the linear current Ia in a direction that follows the right-hand screw rule. This embodiment treats the linear current Ia as an arc generated between the two contacts and utilizes the fact that a magnetic field similar to the magnetic field Ba is generated around the arc. In this embodiment, the arc confinement portion 130 is magnetized by the magnetic field generated around the arc. The Lorentz force acts on the charged particles in the arc, confining the arc within the roughly annular arc confinement portion 130. This reduces the possibility of the arc flying in an unexpected direction and damaging components surrounding the switch.

[0039] Furthermore, the temperature of the arc confinement portion 130 is much lower than the temperature of the arc, which is said to be as high as 1000 degrees Celsius. Therefore, an arc confinement effect can be expected by making it difficult for the arc to approach the arc confinement portion 130 due to the heat shrinkage effect.

[0040] In conventional switches with contacts, the Lorentz force on the arc caused by the strong external magnetic field surrounding the switch can cause the arc to fly towards conductive components or insulators around the contacts, potentially damaging them. However, in this embodiment, the arc is confined by the arc confinement section through the magnetic shielding effect, thus achieving stable current interruption even in the presence of an external magnetic field. The arc generated during current interruption is stabilized within the arc confinement section, suppressing carbonization of the material around the contacts and abnormal arc growth associated with gas generation. As a result, the durability of the contacts is improved, ensuring switch reliability.

[0041] When an inductive load is connected to both contacts, the arc tends to grow due to back electromotive force. Furthermore, when current flows through the coil constituting the inductive load, the external magnetic field surrounding the switch becomes stronger. Even in this situation, according to this embodiment, as described above, the arc is confined by the arc confinement portion due to the magnetic shielding effect, thus achieving stable current interruption even in the presence of an external magnetic field.

[0042] The magnetic material used as the material for arc confinement portion 130 is preferably a soft magnetic material, that is, a magnetic material with high magnetic permeability. In the case of iron, it is particularly preferable to use a material such as soft magnetic electromagnetic soft iron, and to use a material that has been appropriately heat-treated. In the case of soft magnetic ferrite, a manganese-zinc or nickel-zinc-based material is preferred, and a material with a wide temperature range, particularly one that can be used at high temperatures, is preferred. Permalloy can also be used.

[0043] The arc confinement portion 130 can be fixed simultaneously with the support portion 112 by integrally molding the support portion 112 with resin. Alternatively, the arc confinement portion 130 can be fixed to the support portion 112 using an adhesive, preferably a thermosetting adhesive, after it has been molded. Although not shown, the arc confinement portion can also be fixed to the support portion 112 by riveting, embedding, or welding. Furthermore, rather than integrally molding the arc confinement portion 130 with the support portion 112, the arc confinement portion 130 can be made of a magnetic material and the support portion 112 made of a non-magnetic material.

[0044] [Second embodiment]

[0045] Figure 5 (a) is a top view showing the arc confinement mechanism 200 according to this embodiment. Figure 5 (b) is Figure 5(a) is a cross-sectional view taken along line CC. Elements identical to those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted. Unlike the first embodiment, this embodiment illustrates an example in which the arc restraint 130 is secured to the support portion 112 using an adhesive 213. In view of the thermal effects of the arc, a thermosetting adhesive such as epoxy resin is preferably used.

[0046] [Third embodiment]

[0047] exist Figure 6 and Figure 7 Schematic diagram of the arc confinement mechanism 300 according to the present embodiment. Figure 6 (a) is a top view of the arc restraint mechanism 300 in the switch closed state, Figure 6 (b) is Figure 6 (a) DD line cross-sectional view. Figure 7 3 is a cross-sectional view of the arc restraint mechanism 300 in the switch-off state.

[0048] The arc confinement portion 330 is formed into a generally annular tubular shape with an axial dimension larger than that of the arc confinement portion 130 of the first embodiment. The axial end of the arc confinement portion 330 on the fixed contact side is fixed to the substrate 110. The axial dimension h of the arc confinement portion 330 is greater than the sum of the gap g3 between the fixed contact 111 and the movable contact 121 in the OFF state (open stable state) of the switch and the axial dimension t3 of the fixed contact 111 of the arc confinement portion 330. Specifically, this dimension h is expressed as follows.

[0049] h>g3+t3 (2)

[0050] In this way, the gap g3 is entirely surrounded by the arc restricting portion 330 .

[0051] Furthermore, a base portion 322 is provided between the movable plate 120 and the movable contact 121 , thereby ensuring a larger gap between the movable plate 120 and the movable contact 121 than in the first embodiment.

[0052] The following describes the spatial distance d3 between the arc confinement portion 330 and the movable contact 121 in the switch's off state (open stable state). Increasing the diameter of the arc confinement portion 330 can increase the spatial distance d3. On the other hand, when the diameter of the arc confinement portion 330 is relatively large, the distance between the center of the arc generated between the two contacts and the arc confinement portion 330 increases. As a result, the magnetic field at the arc confinement portion 330 weakens, reducing the arc confinement effect. Therefore, the spatial distance d3 is preferably set to be greater than or equal to the gap g3, as shown in the following formula.

[0053] d3≥g3 (3)

[0054] In this manner, although it is difficult to ensure the spatial distance d3 due to the limited dimension h, the spatial distance d3 in the open state can be made larger than or equal to the gap g3.

[0055] According to this embodiment, the axial dimension h of the arc confinement portion 330 is larger than the gap g3, so the arc confinement effect can be expected to be further improved. In addition, instead of providing the base portion 322, the movable plate may be bent to prevent the movable plate from interfering with the arc confinement portion.

[0056] When forming the tubular arc restricting portion 330 , for example, when a metal such as iron is used, it can be formed by press working, and when ferrite is used, powder can be compression molded or injection molded.

[0057] [Fourth embodiment]

[0058] exist Figures 8 to 10 2 shows an arc confinement mechanism 400 according to this embodiment. Figure 8 (a) is a top view of the arc restraint mechanism 400 in the switch closed state, Figure 8 (b) is Figure 8 (a) EE line cross-sectional view. Figure 9 (a) is a top view of the arc restraint mechanism 400, omitting the illustration of the movable plate 120 and the movable contact 121. Figure 9 (b) is Figure 9 (a) FF line cross-sectional view. Figure 10 4 is a cross-sectional view of the arc restraint mechanism 400 in the switch-off state.

[0059] The arc confinement portion 430 is generally annular in shape. The end of the arc confinement portion 430 on the axial fixed contact side is fixed to the substrate 110. The end of the arc confinement portion 430 on the axial movable contact side is provided with four corner portions 431 and four edge portions 432 sandwiched between two adjacent corner portions 431. The edge portions 432 protrude further toward the movable contact than the corner portions 431. The gap between the fixed contact 111 and the movable contact 121 in the switch-off state is surrounded by the four edge portions 432.

[0060] The arc confinement portion 430 is magnetized in the axial direction, so the magnetic force is concentrated on the four edge portions 432 that protrude further toward the axial movable contact than the corner portions 431. Since the gap is surrounded by these four edge portions 432, an arc confinement effect can be achieved.

[0061] According to this embodiment, in addition to achieving the same magnetic effect as the first embodiment, the following additional effects are achieved. Specifically, since the end of the arc confinement portion 430 on the axially fixed contact side is fixed to the substrate 110, while there is no opening on the axially fixed contact side of the arc confinement portion 430, a relatively large gap exists between the corner portion 431 and the movable plate 120 when the switch is closed. Therefore, even when the movable plate 120 moves to open the switch, air flows through this gap, reducing the possibility of a momentary negative pressure around the contacts, which could destabilize the arc.

[0062] like Figure 8 As shown, a radially inwardly extending extension 433 may be provided at the end of the arc restricting portion 430 on the axial fixed contact side. The extension 433 is provided so as not to interfere with the fixed contact 111. The provision of the extension 433 can improve the fixing strength of the arc restricting portion 430.

[0063] All four corner portions 431 do not need to be located axially closer to the fixed contact 111 than the edge portion 432. It is sufficient that at least one corner portion 431 is located axially closer to the fixed contact 111 than the edge portion 432. Alternatively, the axial position of the corner portion 431 may be the same as the axial position of the edge portion 432.

[0064] [Fifth embodiment]

[0065] exist Figure 11 and Figure 12 Schematic diagram of an arc confinement mechanism 500 according to this embodiment. Figure 11 (a) is a top view of the arc restraint mechanism 500 in the switch closed state, Figure 11 (b) is Figure 11 (a) GG line cross-sectional view, Figure 11 (c) is Figure 11 (b) HH line cross-sectional view. Figure 12 4 is a cross-sectional view of the arc restraint mechanism 500 in the switch-off state.

[0066] A second substrate 512 is provided so as to face the substrate 110. The second substrate 512 is supported by a support portion 513 provided on the substrate 110. Furthermore, the arc restraining portion 530 is substantially square-shaped, with its end on the axially movable contact side fixed to the second substrate 512 and its axially fixed contact side being an open surface.

[0067] The arc restricting portion 530 has four corner portions 531 and four edge portions 532a to 532d sandwiched between two adjacent corner portions 531 at its end on the axially fixed contact side. The edge portions 532a to 532d protrude further toward the axially fixed contact 111 than the corner portions 531 do.

[0068] One end of the first edge portion 532a is connected to one end of the second edge portion 532b via a corner portion 531. The other end of the second edge portion 532b is connected to one end of the third edge portion 532c via a corner portion 531. The other end of the third edge portion 532c is connected to one end of the fourth edge portion 532d via a corner portion 531. The other end of the fourth edge portion 532d is connected to the other end of the first edge portion 532a via a corner portion 531.

[0069] Furthermore, the direction in which the first edge portion 532a and the third edge portion 532c face each other is parallel to the longitudinal direction of the movable plate 120, which connects the top end portion 120a and the base end portion 120b of the movable plate 120. The first edge portion 532a is located on the base end portion 120b side, and the third edge portion 532c is located on the top end portion 120a side.

[0070] A relief hole 120c is provided at the base end 120b of the movable plate 120. The first edge portion 532a extends through the relief hole 120c. This relief hole 120c and the two corners 531 at either end of the first edge portion 532a prevent the movable plate 120 from interfering with the arc confinement portion 530.

[0071] As described above, even when the mounting portion of the arc confinement portion 530 is positioned at the end of the axially movable contact rather than the end of the axially fixed contact, an arc confinement effect can be achieved. Alternatively, a sheet-like insulating film 533 may be formed on the end of the arc confinement portion 530 on the axially movable contact side so as to face the movable plate 120 for insulation.

[0072] [Sixth embodiment]

[0073] exist Figure 13 Schematic diagram of an arc confinement mechanism 600 according to this embodiment. Figure 13 (a) is a top view of the arc restraining mechanism 600 , in which the movable plate and the movable contact are omitted. Figure 13 (b) is Figure 13 (a) is a cross-sectional view of line II.

[0074] The arc restricting portion 630 is formed by cutting a sheet of magnetic material into a predetermined width and rolling it into a tubular shape. The overlapped circumferential ends 631 and 632 can be joined by welding or caulking.

[0075] [Application Examples]

[0076] exist Figures 14 to 16 2 shows a case where the arc confinement mechanism 100 according to the first embodiment is mounted on a thermal protector (temperature switch) including a bimetallic element. Figure 14is a top view showing the interior of the thermal protector in a closed circuit state, Figure 15 yes Figure 14 JJ line cross-section diagram. Figure 16 It is a cross-sectional view of the thermal protector in the open circuit state.

[0077] The thermal protector 9 includes an arc confinement mechanism 100 within a housing 90. The first lead 91 of the thermal protector 9 is electrically connected to a fixed contact 111, and the second lead 92 is electrically connected to a movable contact 121. The movable plate 120 is configured to move using a bimetallic element 93 as a driving unit.

[0078] In this manner, the arc confinement mechanism 100 can be applied to the thermal protector 9 as a type of contact switch in order to obtain the arc confinement effect.

[0079] [other]

[0080] For a transfer contact composed of a normally open contact and a normally closed contact, an arc restraint mechanism can also be provided. For example, the arc restraint mechanism 400 of the fourth embodiment can be provided for each of the normally open contact and the normally closed contact. Alternatively, in the fifth embodiment ( Figure 11 and Figure 12 ), a movable contact different from the movable contact 121 may be provided on the upper surface of the movable plate 120, and a fixed contact capable of contacting and separating with the movable contact may be provided on the second substrate 512. In a toggle switch, for example, the arc restraint 130 according to the first embodiment may be provided for each of the normally open contact and the normally closed contact.

[0081] The embodiments described so far are applicable to all contact switches. These include various switches used to interrupt relatively large currents, as well as relays such as electromagnetic relays. In other words, the embodiments described so far are applicable regardless of the type of contact switch's drive mechanism.

[0082] While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made based on the technical concept of the present invention.

[0083] Description of Reference Numerals

[0084] 100, 200, 300, 400, 500, 600 arc restraint mechanism

[0085] 110 substrate

[0086] 111 fixed contacts

[0087] 112 Support

[0088] 120 movable plate

[0089] 121 movable contact

[0090] 130, 330, 430, 530, 630 arc restraint

[0091] g1, g3 gap.

Claims

1. An arc restraint mechanism, characterized in that: have: a first contact and a second contact, both of which can be brought into contact and separated; and an arc confinement portion electrically insulated from a circuit including the first contact and the second contact, an annular portion including a magnetic body, having an axis parallel to a direction of a gap between the first contact and the second contact when the first contact and the second contact are in a non-contact state, and provided so as to surround the gap; The arc restraining portion is made of soft magnetic iron or soft magnetic ferrite.

2. The arc restraint mechanism according to claim 1, wherein: When the first contact and the second contact are in a non-contact state, a sum of a spatial distance between the arc restricting portion and the first contact and a spatial distance between the arc restricting portion and the second contact is greater than the gap.

3. The arc restraint mechanism according to claim 1, wherein: The arc restraining portion is tubular, One axial end portion of the arc restricting portion is mounted on a substrate to which the first contact is fixed. The arc confinement portion on the substrate is electrically insulated from the second contact by a spatial distance.

4. The arc restraint mechanism according to claim 3, wherein: An extension portion extending radially inward is provided at one axial end portion of the arc restraining portion. The extending portion is mounted on a substrate to which the first contact is fixed.

5. The arc restraint mechanism according to claim 3 or 4, wherein: The arc restraining portion is in the shape of a quadrilateral ring. The arc restricting portion has one axial end portion on the second contact side, and is provided with four corner portions and four edge portions sandwiched between two adjacent corner portions. At least one corner portion is located axially closer to the first contact than the edge portion.

6. The arc restraint mechanism according to claim 1, wherein: The first contact is a fixed contact fixed to the first substrate. A second substrate is provided in a manner opposite to the first substrate, One axial end portion of the arc restraining portion is mounted on the second substrate. The second contact is a movable contact fixed to the movable plate. An escape hole is formed in the arc restricting portion, and the escape hole is used to prevent the movable plate from interfering with the arc restricting portion.

7. The arc confinement mechanism according to any one of claims 1 to 4 and 6, wherein: The first contact and the second contact are components of a temperature switch using a bimetallic element.

8. The arc confinement mechanism according to any one of claims 1 to 4 and 6, wherein: The first contact and the second contact are components of an electromagnetic relay.

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