JP2026002119A - Contact material and relay using the same - Google Patents

Abstract

[Problem] To provide a contact material for contacts that have high inrush current resistance and can be stably opened and closed for a long period of time, and a relay using said contact material. [Solution] The contact material has a material structure in which an oxide of metal M is dispersed in a matrix of Ag or the like, said metal M including Sn, and the metal components of the contact material include metal M, the remainder being Ag, and unavoidable impurity metals, and the content of metal M relative to the total weight of all metal components of the contact material is more than 8 wt% and not more than 20 wt%. [Selected Figure] Figure 1

Description

The present invention relates to contact materials and relays using the same.

The moment power is applied to an electrical circuit operating an electric load such as a motor or a lamp load such as an incandescent light bulb, an inrush current, which is a current much larger than the steady-state current, flows through the electrical circuit. When this inrush current occurs, the arc heat from the arc discharge can cause welding and wear to the relay contacts, potentially rendering the relay unusable. In particular, if an inrush current occurs when the moving contacts bounce, this welding and wear can be severe.

As a relay that prevents welding between contacts due to inrush current, for example, an electromagnetic relay with contacts as described in Patent Document 1 has been proposed. The contacts include a current-carrying contact and an inrush-resistant contact that are different in shape and/or material, and a slit that partially separates the contacts. The contacts are said to reduce defects caused by contact welding by, for example, adding flexibility to the spring material with the slit, and by designing the inrush-resistant contact to protrude further than the current-carrying contact, so that the inrush-resistant contact makes contact first, followed by the current-carrying contact.

Japanese Patent Application Laid-Open No. 2005-183097

In recent years, with the need for miniaturization of devices and higher-density relay mounting, there has been a demand for smaller relays. However, the technology described in Patent Document 1 requires the slit as an essential component, which requires a sufficient gap between the contacts. As a result, the relay described in Patent Document 1 is inevitably larger than a normal relay and has a complex mechanism. In other words, there is a problem in that it is difficult to manufacture a compact relay using the contacts described in Patent Document 1. Under these circumstances, there is a need for technology that provides inrush current resistance to the contacts of a compact relay, enabling stable contact opening and closing without welding between the contacts, even under conditions where inrush currents are repeatedly applied.

Therefore, one aspect of the present invention aims to provide a contact material that has high inrush current resistance and can provide contacts that can be stably opened and closed for a long period of time, and a relay that can be miniaturized using this contact material.

In order to solve the above problems, one aspect of the present invention provides a contact material having a material structure in which an oxide of metal M is dispersed in a matrix of Ag and/or an Ag alloy, wherein the metal M includes Sn, the metal components of the contact material include metal M, the remainder Ag, and unavoidable impurity metals, and the content of metal M relative to the total weight of all metal components of the contact material is more than 8 wt% and not more than 20 wt%.

According to the above configuration, Sn provides the contact with wear resistance, adhesion resistance, etc. as an oxide ( _SnO2 ), and the content of the metal M is more than 8 wt%, so sufficient wear resistance and adhesion resistance can be imparted to the contact. Furthermore, according to the above configuration, the content is 20 wt% or less, so the oxide of the metal M can be easily dispersed in the matrix. Therefore, the contact is excellent in mass productivity and contact resistance can be maintained low.

In one embodiment of the contact material of the present invention, the metal M contains Te and/or Bi, and the content of Te and/or Bi relative to the total weight of all metal components of the contact material is 0.2 wt % or more and 1.0 wt % or less.

With the above configuration, it is believed that the differences in melting and boiling points, as well as the differences in brittleness, between Ag and Te and/or Bi give the contacts resistance to inrush current. This makes it possible to separate the contacts with a weak separation force, and reduces contact wear.

A relay according to one aspect of the present invention comprises a fixed piece fixed to a base, a fixed contact provided on the fixed piece, a movable piece fixed at a fixed end to the base and including an elastically deformable portion, a movable contact provided on the movable piece and positioned opposite the fixed contact, a card that presses the movable piece to elastically deform it, connecting the movable contact to the fixed contact, and a drive unit that operates the card by controlling the flow of current to an electromagnet, wherein the movable piece has a contact portion that is convex in a direction facing the card, and the movable piece and the card contact at the contact portion, and the fixed contact and the movable contact contain the contact material described in claim 1 or 2.

With the above configuration, a convex contact portion is provided on the movable piece. Therefore, while the movable piece is pressed against the card and elastically deforms, the position at which the movable piece and the card come into contact is limited to the contact portion. In other words, while the movable piece is pressed against the card and elastically deforms, the pressing force is applied to approximately the same position on the movable piece, so the moment applied to the movable piece can be kept approximately constant. This makes it possible to suppress welding caused by arcing that occurs when the fixed contact and the movable contact momentarily separate when the contact pressure between them is insufficient. Furthermore, because the fixed contact and the movable contact contain the contact material of the present invention, they have excellent resistance to inrush current and wear resistance.

In a relay according to one aspect of the present invention, the contact portion is provided on the movable piece at a position opposite the fixed end with respect to the movable contact.

With the above configuration, the movable piece is pressed on the free end side of the movable contact, resulting in a greater moment of pressure compared to when the movable piece is pressed on the fixed end side of the movable contact. This allows for a higher contact pressure between the fixed contact and the movable contact.

In one aspect of the present invention, the relay contacts the movable piece and the card only at the contact portion throughout the entire movable range in which the card presses against the movable piece.

With the above configuration, the card and the movable piece do not come into contact with each other at any point other than the contact area, preventing wear in areas other than the contact area.

In a relay according to one aspect of the present invention, the convex shape of the contact portion is a curved surface.

With the above configuration, the curved surface of the contact portion comes into contact with the card, reducing wear caused by contact.

In one aspect of the relay of the present invention, when the card presses the movable piece to its fullest extent within the movable range in which the card presses the movable piece, a plane that passes through the contact point where the contact portion and the card are in contact and is parallel to the surface of the movable piece at the portion of the movable piece that extends from the movable contact toward the base of the contact portion does not pass through the area occupied by the member that makes up the movable contact.

Let's assume that the relay is installed so that the normal direction to the surface of the movable piece is horizontal, in other words, so that the contact part is located above the movable contact. In this case, with the above configuration, when the card is pressed all the way into the movable piece, the contact point where the contact part and the card are in contact will not be above the area occupied by the material that makes up the movable contact. Therefore, even when the relay is installed as described above, it is possible to prevent wear powder generated at the contact point from falling onto the movable contact, thereby preventing contact failures caused by wear powder.

In one aspect of the present invention, the contact portion of a relay has a convex cross section along a plane including the main axis direction from the fixed end to the contact portion and the direction in which the contact portion moves when pressed, a linear cross section along a plane normal to the main axis direction, and the width of the opposing surface of the card that faces the contact portion in a direction perpendicular to the main axis direction is shorter than the width of the contact portion in a direction perpendicular to the main axis direction.

The above configuration ensures that the end of the contact portion in a direction perpendicular to the main axis direction does not come into contact with the opposing surface of the card, preventing wear and damage to the opposing surface of the contact portion.

In a relay according to one aspect of the present invention, a cross section of the contact portion taken along a plane including a main axis direction from the fixed end to the contact portion and a direction in which the contact portion moves when pressed is convex, and a cross section taken along a plane having a normal direction in the main axis direction is linear;
The surface of the card facing the contact portion is chamfered at both ends in a direction perpendicular to the main axis direction.

The above configuration ensures that the end of the contact portion in a direction perpendicular to the main axis direction does not come into contact with the opposing surface of the card, preventing wear and damage to the opposing surface of the contact portion.

In one aspect of the relay of the present invention, when the movable contact and the fixed contact are in contact within the movable range in which the card presses against the movable piece, the direction of the force applied by the card to the contact portion is directed toward the fixed end rather than the direction in which the contact portion moves due to the pressure.

The above configuration more effectively prevents the fixed contact from momentarily separating from the movable contact when the movable piece is pressed all the way in by the card. This prevents welding caused by arcing that occurs when the fixed contact and the movable contact are momentarily separated.

One aspect of the present invention provides a contact material that has high inrush current resistance and can provide contacts that can be stably opened and closed for a long period of time, as well as a miniaturizable relay that uses the contact material.

FIG. 2 is a side cross-sectional view of the relay according to the embodiment. FIG. 2 is a perspective view showing the appearance of a movable piece 3. 10A and 10B are side views showing the operation of a movable piece according to a comparative example. 5A and 5B are side views illustrating the operation of the movable piece of the relay according to the embodiment. 1 , showing a state in which the opposing surface 41 of the card 4 and the contact portion 32 of the movable piece 3 are in contact with each other. 10 is a side view showing a state in which the opposing surface 41 and the contact portion 32 of the movable piece 3 are in contact with each other when the movable contact 31 and the fixed contact 21 are in contact with each other. FIG.

An embodiment of one aspect of the present invention (hereinafter also referred to as "the present embodiment") will be described below with reference to the drawings. The present invention is not limited to the configurations described below, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of the present invention.

[1. Contact material]
(1-1. Composition of contact materials, etc.)
The contact material according to this embodiment (hereinafter also referred to as "the contact material of the present invention") has a material structure in which an oxide of a metal M is dispersed in a matrix made of Ag and/or an Ag alloy, wherein the metal M includes Sn, the metal components of the contact material include the metal M with the remainder being Ag and unavoidable impurity metals, and the content of the metal M relative to the total weight of all the metal components of the contact material is more than 8 wt % and not more than 20 wt %.

In small relays, the contact force and opening force between the contacts are set low due to their small size. As a result, if the contacts weld due to an inrush current, it is difficult to open the contacts by increasing these forces. Therefore, the inventors investigated ways to give the contact material inrush current resistance by tweaking the contact material's composition.

Low-resistance Ag or Ag alloys are typically used as the matrix contact material to provide relays with electrical conductivity. However, Ag has a relatively low melting point of 961°C and boiling point of 2155°C, so it melts when an arc is generated by an inrush current, causing the contacts to fuse together. Furthermore, once the contacts are fused together by Ag, it is not easy to separate them. One way to separate the fused Ag would be to apply a strong opening force, such as by using a large electromagnet, but this method is incompatible with the need to miniaturize relays and cannot be adopted.

The inventors therefore dispersed an oxide of metal M in a matrix made of Ag or an Ag alloy, and set the content of metal M to more than 8 wt% and 20 wt% or less of the total weight of all metal components in the contact material. Metal M includes Sn.

The oxide of metal M is used to impart wear resistance and adhesion resistance to the contacts. In the contact material of the present invention, Sn in the form of an oxide (SnO ₂ ) provides wear resistance, adhesion resistance, etc. to the contacts, and the content of metal M is more than 8 wt %, so that sufficient wear resistance and adhesion resistance can be imparted to the contacts.

On the other hand, if the content exceeds 20% by weight, it becomes difficult to disperse the oxide of metal M in the matrix made of Ag and/or Ag alloy, which is undesirable as it causes inconvenience in mass-producing contacts and also leads to increased contact resistance. Since the contact material of the present invention has a content of 20% by weight or less, it is easy to disperse the oxide of metal M in the matrix. Therefore, the contact is highly suitable for mass production and maintains low contact resistance.

From the perspective of imparting wear resistance and welding resistance to the contacts and ensuring mass production of the contacts, the content of the metal M is preferably 10% by weight or more and 18% by weight or less, and more preferably 12% by weight or more and 15% by weight or less.

The matrix is a non-oxide material capable of dispersing an oxide of metal M, and is made of Ag and/or an Ag alloy. The Ag refers to pure Ag. An Ag alloy is an alloy of Ag and metal M, or an alloy of Ag and unavoidable impurity metals. The Ag alloy does not have to be an alloy with a single composition. For example, it may be made of multiple Ag alloys with different amounts of metal M or unavoidable impurity metals dissolved therein. The concentration of metal M or unavoidable impurity metals in the matrix is preferably 4 wt% or less, more preferably 2 wt% or less, and even more preferably 0 wt%.

The metal M is dispersed in the matrix as an oxide, and in the contact material of the present invention, the oxide content is defined based on the content of metal M, which is a metal other than Ag. The content of metal M is defined based on the total weight of all metal components in the contact material. Note that, because Te and/or Bi, which will be described later, are also contained in the contact material as oxides, in this specification the content of Te and/or Bi oxides is defined as the content of Te and/or Bi relative to the total weight of all metal components in the contact material.

Sn is dispersed in the matrix as _SnO2 . From the viewpoint of improving the welding resistance of the contacts, the Sn content relative to the total weight of all metal components of the contact material is preferably 7% by weight or more and 18% by weight or less, more preferably 7% by weight or more and 15% by weight or less, even more preferably 10% by weight or more and 15% by weight or less, and particularly preferably 12% by weight or more and 15% by weight or less.

In addition to Sn, the metal M can further contain other metals such as In, Ni, Te and/or _{Bi, which will be described later. In is dispersed in the matrix as In2O3 ,} and Ni is dispersed in the matrix as NiO. The inclusion of In and/or Ni as the other metal has the advantage of improving the welding resistance of the contact. The other metal may be one type or two or more types.

From the viewpoint of improving the welding resistance of the contacts, the In content relative to the total weight of all metal components of the contact material is preferably 2% by weight or more and 10% by weight or less, and more preferably 4% by weight or more and 8% by weight or less. Furthermore, from the viewpoint of improving the welding resistance of the contacts, the Ni content relative to the total weight of all metal components of the contact material is preferably 0.1% by weight or more and 4% by weight or less, and more preferably 0.05% by weight or more and 2% by weight or less.

The remaining Ag refers to the Ag that constitutes the matrix of Ag and/or Ag alloy. Examples of the unavoidable impurity metals include Li, Na, Mg, Al, Si, K, Ca, Ti, Cr, Mn, Fe, Co, Cu, Zn, Ge, Y, Zr, Nb, Mo, Pd, Cd, Ta, W, Pb, and La. The content of the unavoidable impurity metals is preferably 0% by weight or more and 1% by weight or less, and more preferably 0.05% by weight or more and 1% by weight or less, based on the total weight of all metal components of the contact material.

In addition to the matrix and the oxide of metal M, the contact material of the present invention may contain oxygen and non-metals as unavoidable impurity elements. Examples of non-metals include C, S, and P. The oxygen content of the contact material of the present invention is preferably 0.025% by weight or more and 2% by weight or less, when the weight of the entire contact material is taken as 100% by weight. The content of the non-metals in the contact material of the present invention is preferably 0% by weight or more and 0.1% by weight or less, when the weight of the entire contact material is taken as 100% by weight.

In the contact material of the present invention, it is preferable that the metal M contains Te and/or Bi, and that the content of Te and/or Bi relative to the total weight of all metal components of the contact material is 0.2 wt % or more and 1.0 wt % or less.

Te and Bi have lower melting and boiling points than Ag, and are brittle materials. A brittle material is one that breaks when cracks propagate within the material with almost no plastic deformation when a force is applied. The inventors discovered that higher inrush current resistance can be achieved when the content of Te and/or Bi relative to the total weight of all metal components of the contact material is 0.2 wt % or more and 1.0 wt % or less.

With the above configuration, it is believed that the differences in melting and boiling points, as well as the differences in brittleness, between Ag and Te and/or Bi weaken the weldability between the contacts, making it possible to open the contacts with a weak opening force. Therefore, with the above configuration, it is possible to provide the contacts with high inrush current resistance. Furthermore, this eliminates the need for a large electromagnet that generates a strong opening force, allowing relays equipped with the above contacts to be made smaller.

In this embodiment, metal M contains Sn and Te and/or Bi. As mentioned above, Te and/or Bi impart adhesion resistance to the contact due to differences in melting point and boiling point as well as brittleness compared to Ag. This adhesion resistance is even stronger than that of Sn, and as shown in the examples described below, it is possible to impart stronger adhesion resistance to the contact than when only oxides not containing Te and/or Bi are dispersed in the matrix.

When the content of Te and/or Bi relative to the total weight of all metal components of the contact material is 0.2 wt % or more, it is possible to provide the contact with long-term welding resistance. On the other hand, when the content exceeds 1.0 wt %, the contact tends to wear out quickly. Because the contact material of the present invention has a content of less than 1.0 wt %, it has little effect on contact wear. As a result, contact wear can be reduced.

From this perspective, the content is more preferably 0.4% by weight or more and 0.8% by weight or more, and even more preferably 0.6% by weight or more and 0.8% by weight or more. When Te and Bi are used, the ratio of their contents is not particularly limited, as long as the total content of Te and Bi is 0.2% by weight or more and 1.0% by weight or less. The "total weight of all metal components in the contact material" refers to the sum of the weights of Ag and/or Ag alloys that make up the matrix, metal M contained in the oxide of metal M, and unavoidable impurity metals.

(1-2. Manufacturing method of contact material)
The contact material of the present invention can be manufactured by, for example, the internal oxidation method or the powder metallurgy method. In the internal oxidation method, for example, Ag and/or Ag alloy and metal M are first melted in a high-frequency melting furnace to cast an ingot. Next, the ingot is cut into individual pieces with sides of 3 mm or less and then internally oxidized to manufacture the contact material. The internal oxidation conditions are preferably an oxygen partial pressure of 0.9 MPa or less (above atmospheric pressure), a temperature of 300°C to 900°C, and a treatment time of 24 hours or more.

In powder metallurgy, for example, contact materials are manufactured by mixing powders of Ag and/or Ag alloys with powders of oxides of metal M (both of which have an average particle size of 0.5 to 100 μm) and compressing them to form a powder.

(1-3. Manufacturing method of contacts)
The fixed contacts and movable contacts used in the relays described below can be manufactured, for example, by the following method. First, a contact material obtained by internal oxidation or powder metallurgy is compression molded into a billet with a diameter of 50 mm. Next, this billet is hot extruded and then drawn into a wire with a diameter of 2.3 mm. This is then processed in a header machine to produce a rivet-type contact material.

2. Relay
The relay according to this embodiment comprises a fixed piece fixed to a base, a fixed contact provided on the fixed piece, a movable piece fixed at a fixed end to the base and including an elastically deformable portion, a movable contact provided on the movable piece and arranged opposite the fixed contact, a card that presses the movable piece so as to elastically deform it, thereby connecting the movable contact to the fixed contact, and a drive unit that operates the card by controlling the flow of electricity to an electromagnet, wherein the movable piece has a contact portion that is convex in a direction facing the card, and the movable piece and the card are in contact at the contact portion, and the fixed contact and the movable contact contain the contact material of the present invention.

One embodiment of the present invention will be described in detail below. Figure 1 is a side cross-sectional view of a relay 1 according to this embodiment. As shown in the figure, the relay 1 comprises a fixed piece 2, a movable piece 3, a card 4, a base 5, an armature 6, and a drive unit 7. In practice, each of the above components of the relay 1 is located inside a case (not shown).

The fixed piece 2 is fixed to the base 5, with one end protruding into the case and the other end protruding externally as an external connection terminal. The fixed piece 2 is made of a conductive material, such as Cu. A fixed contact 21 is provided near the end of the part of the fixed piece 2 that protrudes inward. The fixed contact 21 is also made of a conductive material, such as Cu, and is electrically connected to the fixed piece 2.

The movable piece 3 is fixed to the base 5 at its fixed end 33, with one end protruding into the case and the other end protruding externally as an external connection terminal. The movable piece 3 is made of a conductive material, such as Cu. A movable contact 31 is provided on the portion of the movable piece 3 that protrudes into the interior. The movable contact 31 is made of a conductive material, such as Cu, and is electrically connected to the movable piece 3. In this embodiment, the entire movable piece 3 is made of an elastic metal, but this is not limited to this; it is sufficient that at least a portion between the fixed end 33 and the movable contact 31 is provided that is elastically deformable. The movable contact 31 is positioned opposite the fixed contact 21, and elastic deformation of the movable piece 3 allows it to be switched between a state of contact with the fixed contact 21 and a state of no contact.

A contact portion 32 is provided on the free end of the portion of the movable piece 3 that protrudes into the case. When the contact portion 32 abuts against the opposing surface 41 of the card 4, a pressing force from the card 4 is applied to the movable piece 3.

In the example shown in Figure 1, the direction in which the movable piece 3 extends from the base 4 into the case is vertically upward, but the arrangement direction of the relay 1 is not limited to this; for example, the direction in which the movable piece 3 extends from the base 4 into the case may be horizontal.

The card 4 is positioned between the drive unit 7 and the movable piece 3, and transmits the pressing force from the armature 6, which is rotated by the drive unit 7, to the movable piece 3. The card 4 is made of, for example, resin, but is not limited to this.

The card 4 has a base formed of a plate-like member extending in the vertical direction, and one end of the card 4 (the lower end in Figure 1), the card fixed end 42, is rotatably held relative to the base 5. The card 4 has a protrusion facing the armature 6, and when the armature 6 abuts against this protrusion, a pressing force from the armature 6 is applied to the card 4.

The other end of the card 4 (the upper end in Figure 1) has an opposing surface 41. When a pressing force from the armature 6 is applied to the protrusion, the card 4 rotates around the fixed end 42, causing the opposing surface 41 to come into contact with the contact portion 32 of the movable piece 3, and a pressing force is applied to the movable piece 3.

The drive unit 7 generates an electromagnetic force to operate the card 4. The drive unit 7 is composed of a coil, bobbin, iron core, yoke, etc., and the electromagnetic force is switched on and off by external current control. The armature 6 is rotatably supported at the upper end of the yoke of the drive unit 7. The armature 6 rotates due to the electromagnetic force generated by the coil of the drive unit 7, pressing against the card 4.

Figure 2 is a perspective view showing the appearance of the movable piece 3. As shown in the figure, the movable piece 3 is formed by bending a molded plate-shaped metal member. As mentioned above, a contact portion 32 is provided on the free end side of the movable piece 3.

More specifically, the contact portion 32 is located on the movable piece 3, opposite the fixed end 33 relative to the movable contact 31. With this configuration, the movable piece 3 is pressed on the free end side of the movable contact 31, resulting in a greater moment of pressure compared to when the movable contact 31 is pressed on the fixed end 33 side. This allows for a higher contact pressure between the fixed contact 21 and the movable contact 31.

The contact portion 32 is made of a member that is convex in the direction facing the facing surface 41 of the card 4. The convex shape of the contact portion 32 is also curved. This allows the curved surface of the contact portion 32 to come into contact with the facing surface 41 of the card 4, reducing wear on the card 4 due to contact.

Furthermore, the cross section of the contact portion 32 taken along a plane P1 including the main axis direction AX from the fixed end 33 to the contact portion 32 and the direction D1 in which the contact portion 32 moves when pressed is convex toward the opposing surface 41, while the cross section taken along a plane P2 normal to the main axis direction AX is linear. In other words, the contact portion 32 is a curved surface that extends linearly in a direction perpendicular to the main axis direction AX.

In the example shown in Figure 2, the convex shape of the contact portion 32 is formed by bending the plate-like metal that makes up the movable piece 3, but this is not limited to this. For example, the convex shape may be formed by increasing the thickness of the contact portion 32. Furthermore, the contact portion 32 may be formed from a material separate from the material that makes up the movable piece 3. In this case, the contact portion 32 may be made of resin.

In addition, in the example shown in Figure 2, a slit is provided in the area between the fixed end 33 and the movable contact 31, but this is not limited to this and the slit need not be provided. Alternatively, a structure in which a movable contact 31 is provided on each side of the slit, i.e., a structure in which two movable contacts 31 are provided, may also be used.

Next, we will explain the operation when the card 4 pushes the movable piece 3. Figure 3 shows, as a comparative example, the operation of a configuration in which a protrusion 410 is provided on the card 40 side and no protrusion is provided on the movable piece 30 side. 301 shows the state at the time when the protrusion 410 of the card 40 comes into contact with the movable piece 30. In this state, the distance between the center of the movable contact 310 and the contact point P10 between the protrusion 410 and the movable piece 30 is defined as L10. 302 also shows the state in which the movable piece 30 is elastically deformed by the pressure of the card 40, and the movable contact 310 comes into contact with the fixed contact 210 on the fixed piece 20. In this state, the distance between the center of the movable contact 310 and the contact point P10 between the protrusion 410 and the movable piece 30 is defined as L20.

While the free end of the movable piece 30 is being pressed by the card 40, it moves in a generally arcuate shape around the fixed end of the movable piece 30. The protrusion 410 of the card 40 also moves in a generally arcuate shape around the fixed end of the card 40. Therefore, when the arrangement shown in FIG. 3 changes from the state shown in 301 to the state shown in 302, the distance L20 becomes shorter than the distance L10. In other words, the contact point P10 between the protrusion 410 and the movable piece 30 moves closer to the movable contact 310. In this case, the position at which the pressing force is applied to the movable piece 30 changes, and the moment applied to the movable piece 30 decreases. Therefore, if the contact pressure between the fixed contact and the movable contact is insufficient, the fixed contact and the movable contact momentarily separate, increasing the likelihood of welding due to an arc.

On the other hand, Figure 4 shows the operation of the relay 1 according to this embodiment. 401 shows the state when the facing surface 41 of the card 4 comes into contact with the contact portion 32 of the movable piece 3. In this state, the distance between the center of the movable contact 31 and the contact point P1 between the facing surface 41 and the contact portion 32 is defined as L1. 402 also shows the state when the movable piece 3 is elastically deformed by the pressure of the card 4, and the movable contact 31 comes into contact with the fixed contact 21 on the fixed piece 2. In this state, the distance between the center of the movable contact 31 and the contact point P1 between the facing surface 41 and the contact portion 32 is defined as L2.

In the configuration of the relay 1 according to this embodiment, a convex contact portion 32 is provided on the movable piece 3 side. Therefore, while the movable piece 3 is pressed against the card 4 and elastically deforms, the position at which the movable piece 3 and the card 4 come into contact is limited to the contact portion 32. In other words, distance L1 and distance L2 are approximately equal.

As a result, while the movable piece 3 is being pressed against the card 4 and elastically deforming, the pressing force is applied to approximately the same position on the movable piece 3, and the moment applied to the movable piece 3 can be kept approximately constant. This prevents welding caused by arcing that occurs when the fixed contact 21 and the movable contact 31 momentarily separate when the contact pressure between them is insufficient.

Furthermore, the fixed contact 21 and the movable contact 31 are made of the contact material of the present invention, which provides excellent welding resistance from a material perspective as well. Therefore, the relay 1 can be said to have a configuration that provides sufficient resistance to inrush currents from both a structural and material perspective, while also allowing for miniaturization.

In other words, the above configuration makes it possible to provide a miniaturized relay with excellent inrush current resistance, something that did not previously exist. Therefore, the above relay 1 can be widely used in applications where miniaturization is strongly required, such as smart meters and LED lighting applications, but is not limited to these.

Furthermore, as shown in Figure 4, throughout the entire movable range in which the card 4 presses against the movable piece 3, the movable piece 3 and the card 4 come into contact only at the contact portion 32. In other words, the card 4 and the movable piece 3 do not come into contact at any point other than the contact portion 32, preventing wear in areas other than the contact portion 32.

In addition, 402 in Figure 4 shows the state in which the card 4 presses the movable piece 3 to the furthest extent within the movable range in which the card 4 presses the movable piece 3. In this state, a surface S2 that passes through contact point P1 where the contact portion 32 and the card 4 are in contact, and is parallel to the movable piece surface 34 of the portion of the movable piece 3 that extends from the movable contact 31 toward the base of the contact portion 32, does not pass through the area occupied by the material that makes up the movable contact 31.

The state shown in Figure 4 shows the relay 1 installed so that the normal direction of the movable piece surface 34 is horizontal, in other words, so that the contact portion 32 is positioned above the movable contact 31. In this case, when the card 4 presses the movable piece 3 all the way in, the contact point P1 where the contact portion 32 and the card 4 are in contact will not be above the area occupied by the material that makes up the movable contact 31. This prevents wear debris generated at contact point P1 from falling onto the movable contact 31, thereby preventing contact failures caused by wear debris.

Figure 5 is a plan view of Figure 1, viewed from above, showing the state in which the facing surface 41 of the card 4 and the contact portion 32 of the movable piece 3 are in contact. As shown in the figure, the width of the facing surface 41 of the card 4 in a direction perpendicular to the main axis direction AX, i.e., in the horizontal direction (up and down in Figure 5), is shorter than the width of the contact portion 32 in a direction perpendicular to the main axis direction AX, i.e., in the horizontal direction (up and down in Figure 5). This configuration prevents the end of the contact portion 32 in the direction perpendicular to the main axis direction AX from coming into contact with the facing surface 41 of the card 4, thereby preventing wear and damage to the facing surface 41.

In addition, chamfering 411 is applied to both ends of the facing surface 41 of the card 4 in a direction perpendicular to the main axis direction AX, i.e., in the horizontal direction (up and down in Figure 5). This configuration prevents the ends of the contact portion 32 in a direction perpendicular to the main axis direction AX from coming into contact with the facing surface 41 of the card 4, preventing wear and damage to the facing surface 41.

In the example shown in Figure 5, the chamfering 411 is an arc-shaped R-chamfer, but this is not limited to this and may be, for example, a C-chamfer, which is a linear chamfer at a 45-degree angle.

Furthermore, when the opposing surface 41 is chamfered 411 as described above, the width of the portion of the opposing surface 41 that is inside the chamfered portion 411 should be shorter than the width of the contact portion 32 in a direction perpendicular to the main axis direction AX.

Furthermore, the contact portion 32 may be chamfered in a direction perpendicular to the main axis direction AX, i.e., at both ends in the horizontal direction (the up and down direction in Figure 5). If this chamfering is an R-chamfer, the width of the opposing surface 41 in the direction perpendicular to the main axis direction AX may be longer than the width of the contact portion 32 in the direction perpendicular to the main axis direction AX.

In the example shown in Figure 5, the opposing surface 41 is a gently curved surface when viewed from above, but it may also be a completely flat surface. In addition, the contact portion 32 is a completely flat surface when viewed from above, but it may also be a gently curved surface.

Figure 6 is a side view showing the state in which the opposing surface 41 and the contact portion 32 of the movable piece 3 are in contact when the movable contact 31 and the fixed contact 21 are in contact. As shown in the figure, within the movable range in which the card 4 presses the movable piece 3, when the movable contact 31 and the fixed contact 21 are in contact, the direction D2 of the force applied by the card 4 to the contact portion 32 is directed toward the fixed end 33 rather than the direction D1 in which the contact portion 32 moves due to the pressing. This configuration more effectively prevents the fixed contact 21 and the movable contact 31 from momentarily separating when the movable piece 3 is pressed all the way in by the card 4. This prevents welding caused by arcing that occurs when the fixed contact 21 and the movable contact 31 momentarily separate.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

〔summary〕
The present invention includes the following aspects.
<1> A contact material having a material structure in which an oxide of a metal M is dispersed in a matrix made of Ag and/or an Ag alloy, wherein the metal M includes Sn, the metal components of the contact material include the metal M with the remainder being Ag and unavoidable impurity metals, and the content of the metal M relative to the total weight of all the metal components of the contact material is more than 8 wt % and not more than 20 wt %.
<2> The contact material according to <1>, wherein the metal M contains Te and/or Bi, and the content of the Te and/or Bi relative to the total weight of all metal components of the contact material is 0.2 wt % or more and 1.0 wt % or less.
<3> a fixing piece fixed to the base;
a fixed contact provided on the fixed piece;
a movable piece fixed to the base at a fixed end and including an elastically deformable portion;
a movable contact provided on the movable piece and arranged opposite the fixed contact;
a card that presses the movable piece so as to elastically deform it, thereby connecting the movable contact to the fixed contact;
a driving unit that controls the energization of an electromagnet to operate the card;
Equipped with
the movable piece has a contact portion that is convex in a direction facing the card, the movable piece and the card come into contact with each other at the contact portion;
The fixed contact and the movable contact contain the contact material according to <1> or <2>.
relay.
<4> The relay according to <3>, wherein the contact portion is provided on the movable piece at a position opposite the fixed end with respect to the movable contact.
<5> The relay according to <3> or <4>, wherein the movable piece and the card are in contact only at the contact portion throughout the entire movable range in which the card presses against the movable piece.
<6> The relay according to any one of <3> to <5>, wherein the convex shape of the contact portion is a curved surface.
<7> A relay described in any one of <3> to <6>, wherein, within the movable range in which the card presses the movable piece, when the card presses the movable piece to the farthest extent, a plane that passes through the contact point where the contact portion and the card are in contact and is parallel to the surface of the movable piece at the portion of the movable piece that extends from the movable contact toward the base of the contact portion does not pass through the area occupied by the material that constitutes the movable contact.
<8> In the contact portion, a cross section taken along a plane including a main axis direction from the fixed end to the contact portion and a direction in which the contact portion moves when pressed is convex, and a cross section taken along a plane having the main axis direction as a normal direction is linear,
The relay according to any one of <3> to <7>, wherein the width of the opposing surface of the card that faces the contact portion in a direction perpendicular to the main axis direction is shorter than the width of the contact portion in the direction perpendicular to the main axis direction.
<9> In the contact portion, a cross section taken along a plane including a main axis direction from the fixed end to the contact portion and a direction in which the contact portion moves when pressed is convex, and a cross section taken along a plane having the main axis direction as a normal direction is linear,
The relay according to any one of <3> to <8>, wherein both ends of a facing surface of the card that faces the contact portion are chamfered in a direction perpendicular to the main axis direction.
<10> A relay described in any one of <3> to <9>, wherein, within the movable range in which the card presses against the movable piece, when the movable contact and the fixed contact are in contact, the direction of the force applied by the card to the contact portion is directed toward the fixed end rather than the direction in which the contact portion moves due to the pressing.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples.

Example 1
(Preparation of contact material and manufacturing of contacts using same)
Contact materials were prepared containing Sn, In and Bi, or Sn, In and Te as metal M in a matrix of Ag, in the contents shown in Table 1. The contact materials were prepared by the internal oxidation method. That is, Ag and the metal M shown in Table 1 were first melted in a high-frequency melting furnace to produce an ingot. Next, the ingot was cut into individual pieces with sides of 3 mm or less, and then internally oxidized to produce the contact materials.

The internally oxidized pieces were collected and compression molded to form a 50 mm diameter billet. This billet was then hot extruded and subsequently drawn into a 1.8 mm diameter wire, which was then processed using a header machine to produce rivet-type contact materials. In this example, both the movable and fixed contacts were rivet contacts with head dimensions of 2.3 mm diameter x 0.4 mm height.

The resulting contacts were incorporated into the relay 1 shown in Figure 1 as the fixed contact 21 and the movable contact 31, respectively, and their resistance to inrush current was evaluated.

(Evaluation of resistance to inrush current)
TV8 (inrush current 117 A), TV5 (inrush current 78 A), and E-ballast 3 (inrush current 258 A) were selected as ratings for evaluating resistance to inrush current. A tungsten lamp was used as the load. Relays 1 (11 units in total) each incorporating fixed contacts 21 and movable contacts 31 made of the contact materials shown in Table 1 were assembled into the tungsten lamp and subjected to an electrical endurance life test. The external size of relay 1 was 5000 ^mm3 or less. Therefore, relay 1 corresponds to a so-called small relay.

The electrical endurance life test was conducted as follows: The relay was mounted on a test circuit capable of loading inrush current, and the test conditions were AC 250V with an opening/closing cycle of 1 second (ON)/9 seconds (OFF). Various inrush current loads (TV3, TV8, E-ballast 3) were applied, and the number of openings and closings until failure was measured.

The contact pressure between the fixed contact 21 and the movable contact 31 is set to 0.4 N or less, and the suction force of the coil of the drive unit 7 is set to 1.5 N or less.

The results are shown in Table 1. For TV5 and TV8, a product is deemed to have passed if it achieved 25,000 or more opening and closing cycles. For E-Ballast 3, a product is deemed to have passed if it achieved 6,000 or more opening and closing cycles.

The values listed in the composition column in the table represent the percentage content of all metal components in the contact material relative to the total weight, and "%" means weight percent.

The contact materials used in Examples 21 to 24 contained a total of more than 8.0 wt. % and 20 wt. % or less of Sn and In as the metal M, and correspond to the contact materials of the present invention. They did not contain Te or Bi. These contact materials exhibited inrush current resistance that passed all of the TV5, TV8, and E ballast tests.

The contact materials used in Examples 25 to 31 contained a total of more than 8.0 wt. % and 20 wt. % or less of Sn and In, and Te or Bi, as the metal M, and correspond to the contact materials of the present invention. The Te or Bi content was 0.1 wt. % or 1.1 wt. These contact materials did not meet the pass criteria for TV8 and E ballast, but exhibited inrush current resistance that was acceptable for TV5.

The contact materials used in Examples 1 to 20 contain Sn and In, and Te or Bi, as metal M, in a total amount of more than 8.0 wt.% and up to 20 wt.%, and fall under the category of contact materials of the present invention. The Te or Bi content is 0.2 wt.%, 0.5 wt.%, or 1 wt.%. These contact materials exhibited inrush current resistance that passed all of the TV5, TV8, and E-ballast tests, and the results for TV8 and E-ballast 3 were significantly better than those for Examples 21 to 24, which have the same total metal M content.

Comparing the results of Examples 1 to 20 with those of Examples 25 to 31, it can be seen that when the condition of a Te or Bi content of 0.2 wt% or more and 1.0 wt% or less is met, the inrush current resistance is significantly improved for all of TV5, TV8 and E-ballast 3 compared to when this condition is not met.

The contact materials used in Comparative Examples 1 to 3 had a metal M content of 21% by weight, and therefore do not qualify as contact materials of the present invention. Furthermore, the contact materials used in Comparative Examples 4 to 6 had a metal M content of 8% by weight or less, and therefore do not qualify as contact materials of the present invention. The results of Comparative Examples 1 to 3, 5, and 6 show that when the requirement that the metal M content be greater than 8% by weight and less than or equal to 20% by weight is not met, resistance to inrush current is insufficient, even if the Te or Bi content is 0.2% by weight or more and 1.0% by weight or less.

The present invention can be used to manufacture miniaturizable relays with excellent inrush current resistance.

DESCRIPTION OF SYMBOLS 1 Relay 2 Fixed piece 3 Movable piece 4 Card 5 Base 6 Armature 7 Drive unit 21 Fixed contact 31 Movable contact 32 Contact part of movable piece 33 Fixed end of movable piece 34 Movable piece surface at part where movable piece extends from movable contact towards base of contact part 41 Opposing surface of card with respect to contact part 42 Fixed end of card S2 Surface parallel to movable piece surface at part where movable piece extends from movable contact towards base of contact part

Claims (10)

A contact material having a material structure in which an oxide of metal M is dispersed in a matrix of Ag and/or Ag alloy, wherein the metal M includes Sn, the metal components of the contact material include metal M, the remainder Ag, and unavoidable impurity metals, and the content of metal M relative to the total weight of all metal components of the contact material is more than 8 wt% and not more than 20 wt%. The contact material according to claim 1, wherein the metal M includes Te and/or Bi, and the content of Te and/or Bi relative to the total weight of all metal components of the contact material is 0.2 wt % or more and 1.0 wt % or less. a fixed piece fixed to the base;
a fixed contact provided on the fixed piece;
a movable piece fixed to the base at a fixed end and including an elastically deformable portion;
a movable contact provided on the movable piece and arranged opposite the fixed contact;
a card that presses the movable piece so as to elastically deform it, thereby connecting the movable contact to the fixed contact;
a driving unit that controls the energization of an electromagnet to operate the card;
Equipped with
the movable piece has a contact portion that is convex in a direction facing the card, the movable piece and the card come into contact with each other at the contact portion;
The fixed contact and the movable contact contain the contact material according to claim 1 or 2.
relay. The relay described in claim 3, wherein the contact portion is provided on the movable piece at a position opposite the fixed end relative to the movable contact. The relay described in claim 3, wherein the movable piece and the card contact only at the contact portion throughout the entire movable range in which the card presses against the movable piece. The relay described in claim 3, wherein the convex shape of the contact portion is a curved surface. A relay as described in claim 3, wherein, when the card presses the movable piece to its fullest extent within the movable range in which the card presses the movable piece, a plane that passes through the contact point where the contact portion and the card are in contact and is parallel to the movable piece surface at the portion of the movable piece that extends from the movable contact toward the base of the contact portion does not pass through the area occupied by the member that constitutes the movable contact. the contact portion has a convex cross section along a plane including a main axis direction from the fixed end to the contact portion and a direction in which the contact portion moves when pressed, and a linear cross section along a plane having a normal to the main axis direction,
4. The relay according to claim 3, wherein a width of an opposing surface of the card that faces the contact portion in a direction perpendicular to the main axis direction is shorter than a width of the contact portion in the direction perpendicular to the main axis direction. the contact portion has a convex cross section along a plane including a main axis direction from the fixed end to the contact portion and a direction in which the contact portion moves when pressed, and a linear cross section along a plane having a normal to the main axis direction,
4. The relay according to claim 3, wherein both ends of a surface of said card facing said contact portion are chamfered in a direction perpendicular to said main axis direction. A relay as described in claim 3, wherein, within the movable range in which the card presses against the movable piece, when the movable contact and the fixed contact are in contact, the direction of the force applied by the card to the contact portion is directed toward the fixed end rather than the direction in which the contact portion moves due to the pressing force.