Molded vacuum valve

Abstract

To provide a mold vacuum valve capable of alleviating the generation of internal stress at a triple point where an arc shield, an insulating porcelain tube, and an insulating resin layer contact each other.SOLUTION: A mold vacuum valve includes a cylindrical insulating container 1 that accommodates a pair of electrodes E1 and E2 so as to be contactable / separable and opens at both ends in the direction of contact / separation of the electrodes, an insulating resin layer Ir molded to cover the outside of the insulating container, and a cylindrical arc shield 5 provided in an insulating container and extending along the direction of contact / separation to enclose the pair of electrodes, and the insulating container includes cylindrical insulating porcelain tubes 1a and 1b connected to both ends of the arc shield in the direction of contact / separation, and stress relaxation means 13 for relieving stress generated at boundary parts R1 and R2 where the insulating resin layer, the arc shield, and the insulating porcelain tube are close to each other.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to molded vacuum valves.

Background Art

[0002] As a power receiving and distribution switchgear installed in buildings and large-scale facilities, for example, a switchgear equipped with a switch such as a circuit breaker or a disconnector is known. A vacuum valve is applied to the switchgear as a component of the switch. The interior of the vacuum valve is maintained in a constant insulating state by an insulating container, and a pair of electrodes are housed inside the insulating container so as to be separable and connectable. In this case, by separating and connecting the pair of electrodes, fault current interruption and load current switching are performed, and power is stably supplied from the switchgear.

Prior Art Literature

Patent Literature

[0003]

Patent Literature 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] By the way, as the above-mentioned vacuum valve, there is one molded with an insulating resin layer so as to cover the outside of the insulating container (for example, a molded vacuum valve). In a molded vacuum valve, the insulating container is a composite cylinder in which insulating porcelain tubes are connected to both ends of an arc shield disposed so as to surround a pair of electrodes. In this case, triple points (also referred to as triple junctions) where the arc shield, the insulating porcelain tube, and the insulating resin layer are in contact with each other are formed at both ends of the arc shield.

[0005] At the triple junction, the arc shield, insulating tube, and insulating resin layer have different coefficients of linear expansion (also called thermal expansion), and the boundaries of these three are in contact with each other without any gaps. Here, if we consider, for example, the case where the length and volume of the above three expand due to a rise in temperature, the rate at which their lengths and volumes expand will also differ from one another, according to their different coefficients of linear expansion (thermal expansion).

[0006] Therefore, depending on the degree of their differing expansion rates, internal stress can occur at the triple point. Depending on the magnitude of this internal stress, defects such as delamination between the arc shield and the insulating resin layer, or cracks in the insulating resin layer, may occur. In such cases, for example, partial discharge may occur during the operation of the vacuum valve (especially when voltage is applied), resulting in the destruction of the insulating resin layer and inevitably leading to a ground fault.

[0007] Therefore, the object of the present invention is to provide a molded vacuum valve that can alleviate the generation of internal stress at the triple point where the arc shield, insulating tube, and insulating resin layer come into contact with each other. [Means for solving the problem]

[0008] According to the embodiment, the device comprises a cylindrical insulating container that houses a pair of electrodes so as to be able to move them apart and has openings at both ends in the direction in which the electrodes move apart and apart; an insulating resin layer molded to cover the outside of the insulating container; and a cylindrical arc shield provided on the insulating container and extending along the direction in which the electrodes move apart and apart to surround the pair of electrodes. The insulating container further comprises cylindrical insulating tubes connected to both ends of the arc shield in the direction in which the electrodes move apart and apart, and stress relief means for relieving stress generated at the boundary where the insulating resin layer, the arc shield, and the insulating tubes are in close proximity to each other. The stress relief means is composed of a metallic material containing either nickel or tin, or a metallic material containing both nickel and tin. . [Brief explanation of the drawing]

[0009] [Figure 1] A cross-sectional view showing the internal structure of a molded vacuum valve according to the first embodiment. [Figure 2]A cross-sectional view showing the arrangement configuration of the stress relaxation means shown in Figure 1. [Figure 3] A cross-sectional view showing another arrangement configuration of the stress relaxation means shown in Figure 1. [Figure 4] A partial cross-sectional view showing the arrangement configuration of the silane coupling layer formed on the surface of the stress relaxation means in the second embodiment. [Figure 5] A flowchart illustrating the process of forming the silane coupling layer in Figure 4. [Figure 6] This figure shows a comparison of the adhesive strength between the stress relaxation means and the insulating resin layer, with and without the silane coupling layer. [Figure 7] A cross-sectional view showing the arrangement configuration of the stress relaxation means according to the first modified example. [Figure 8] A cross-sectional view showing the arrangement configuration of the stress relaxation means according to the second modified example. [Figure 9] A cross-sectional view showing the arrangement configuration of the stress relief means according to the third modified example. [Figure 10] A cross-sectional view showing the arrangement configuration of the stress relaxation means according to the fourth modified example. [Modes for carrying out the invention]

[0010] "First Embodiment" Figure 1 shows the basic structure of a molded vacuum valve P (hereinafter referred to as vacuum valve P) according to the first embodiment. The vacuum valve P comprises a fixed electrode E1, a movable electrode E2, an insulating container 1 (also called a vacuum container), a fixed-side sealing fitting 2, a movable-side sealing fitting 3, an airtightness maintenance mechanism 4, an arc shield 5, a fixed-side external shield 6, a movable-side external shield 7, and an insulating resin layer Ir. In the example in Figure 1, the fixed electrode E1, the movable electrode E2, and the airtightness maintenance mechanism 4 are housed in the insulating container 1.

[0011] As shown in Figure 1, the insulating container 1 has a hollow cylindrical shape centered on a virtual axis Px that defines the center of the vacuum valve P. The insulating container 1 has openings at both ends when viewed in the direction of the virtual axis Px (in other words, the direction of contact and separation of electrodes E1 and E2, which will be described later). Both openings (fixed-side opening K1 and movable-side opening K2) are covered by a fixed-side sealing fitting 2 and a movable-side sealing fitting 3. That is, the fixed-side opening K1 is closed by the fixed-side sealing member 2, and the movable-side opening K2 is closed by the movable-side sealing fitting 3.

[0012] The insulating container 1 is constructed by connecting insulating tubes (fixed insulating tube 1a and movable insulating tube 1b) to both ends (one end T1 and the other end T2) of the arc shield 5 in the direction of the virtual axis Px (the direction in which electrodes E1 and E2 move away from each other). Specifically, the fixed insulating tube 1a is connected to one end T1 of the arc shield 5, and the movable insulating tube 1b is connected to the other end T2 of the arc shield 5.

[0013] The insulating tubes 1a and 1b are constructed to the same thickness. The arc shield 5 is constructed to be thinner than the insulating tubes 1a and 1b. These insulating tubes 1a and 1b and the arc shield 5 form a hollow cylindrical shape centered on a virtual axis Px, and their respective diameters (radius, diameter) are set to be approximately the same. As a result, both insulating tubes 1a and 1b, and the arc shield 5 interposed between them, are arranged in a straight line along the virtual axis Px.

[0014] In this state, the arc shield 5 is positioned to surround the pair of electrodes E1 and E2, specifically to house the fixed contact 8 of the fixed electrode E1 and the movable contact 10 of the movable electrode E2, which will be described later, inside it.

[0015] Here, focusing on the inner diameters of the insulating porcelain tubes 1a, 1b and the arc shield 5, the inner diameters of the insulating porcelain tubes 1a, 1b and the arc shield 5 are set to be identical to each other. On the other hand, focusing on the outer diameters of the insulating porcelain tubes 1a, 1b and the arc shield 5, the outer diameters of the insulating porcelain tubes 1a, 1b are set to be identical to each other, and the outer diameter of the arc shield 5 is set to be smaller than that of the insulating porcelain tubes 1a, 1b.

[0016] The outer diameter configuration of the insulating porcelain tubes 1a, 1b and the arc shield 5 will be described in detail. The outer peripheral surfaces Sa, Sb of the hollow cylindrical insulating porcelain tubes 1a, 1b form a cylindrical surface centered on the imaginary axis Px. The diameters of these cylindrical surfaces (i.e., the outer peripheral surfaces Sa, Sb) (i.e., the aforementioned outer diameters of the insulating porcelain tubes 1a, 1b) are set to be identical to each other.

[0017] On the other hand, the outer peripheral surface 5s of the hollow cylindrical arc shield 5 forms a cylindrical surface centered on the imaginary axis Px. The diameter of this cylindrical surface (i.e., the outer peripheral surface 5s) (i.e., the aforementioned outer diameter of the arc shield 5) is set to be smaller than the diameters of the outer peripheral surfaces Sa, Sb of the insulating porcelain tubes 1a, 1b. Accordingly, the outer shape of the insulating container 1 has a contour in which the arc shield 5 is depressed (recessed, dented) radially inward relative to the insulating porcelain tubes 1a, 1b.

[0018] In this case, the fixed-side sealing fitting 2 and the movable-side sealing fitting 3 are made of, for example, a metal material mainly composed of stainless steel. The insulating porcelain tubes 1a, 1b are made of, for example, an insulating material such as alumina ceramic. The arc shield 5 is made of, for example, a metal material mainly composed of copper, stainless steel or the like.

[0019] Further, the fixed electrode E1 and the movable electrode E2 are configured concentrically about the imaginary axis Px, and extend aligned along the imaginary axis Px. The fixed electrode E1 includes a fixed contact 8 and a fixed energizing shaft 9. The movable electrode E2 includes a movable contact 10 and a movable energizing shaft 11. The fixed energizing shaft 9 and the movable energizing shaft 11 each have a cylindrical shape with the same diameter, and are made of a material with high electrical conductivity (for example, copper (Cu), copper alloy, silver (Ag)).

[0020] The fixed contact 8 and the movable contact 10 have the same contour shape and are arranged opposite each other. The fixed contact 8 is connected to one end of the fixed energizing shaft 9, and the other end of the fixed energizing shaft 9 is fixed to the vacuum valve P so as not to move along the virtual axis Px via the fixed-side sealing fitting 2. The movable contact 10 is connected to one end of the movable energizing shaft 11, and the other end of the movable energizing shaft 11 is connected to an operating mechanism (not shown) via the movable-side sealing fitting 3.

[0021] In this configuration, as shown in Figure 1, the movable energizing shaft 11 is moved along the virtual axis Px by the operating mechanism. This allows the movable contact 10 to move toward and toward the fixed contact 8. As a result, the vacuum valve P can be opened and closed (i.e., the pair of electrodes E1 and E2 can be moved toward and toward each other).

[0022] Furthermore, an airtightness maintenance mechanism 4 is positioned between the movable energizing shaft 11 and the movable side sealing fitting 3. The airtightness maintenance mechanism 4 is composed of an expandable bellows, and the bellows (airtightness maintenance mechanism) 4 is made of a thin metal such as stainless steel. The bellows 4 has a bellows-like shape that can expand and contract in the direction of the virtual axis Px, and covers the outside of the movable energizing shaft 11 without any gaps.

[0023] The bellows 4 is joined to the movable side sealing fitting 3 at one end without any gaps, and to the movable energizing shaft 11 at the other end without any gaps. As a result, the inside of the insulating container 1 is always maintained in an airtight state (i.e., a vacuum state). Consequently, even when the movable energizing shaft 11 is moved along the virtual axis Px during the opening and closing operation of the vacuum valve P, no air enters the inside of the insulating container 1.

[0024] Such a vacuum valve P is molded into a cylindrical shape by an insulating resin layer Ir. The insulating resin layer Ir is molded to completely cover the outside of the insulating container 1 (i.e., the outer surface 5s of the arc shield 5, and the outer surfaces Sa and Sb of the insulating tubes 1a and 1b) without any gaps. The insulating resin layer Ir is composed of, for example, epoxy resin, unsaturated polyester resin, etc.

[0025] The vacuum valve P, which is molded into a cylindrical shape using an insulating resin layer Ir, is provided with a conductive grounding layer 12 that covers the outside of the insulating resin layer Ir. The grounding layer 12 is formed by, for example, applying a conductive paint to the outer circumference of the cylindrical insulating resin layer Ir and is grounded.

[0026] Furthermore, the vacuum valve P is provided with external shields (fixed-side external shield 6, movable-side external shield 7) to mitigate the concentration of electric fields on the sealing fittings 2 and 3 when energized or open. The external shields 6 and 7 are made of a metal (conductive) material such as aluminum or stainless steel (SUS).

[0027] The fixed-side external shield 6 extends in the direction of the virtual axis Px so as to cover the fixed-side sealing fitting 2 and partially surround the outside of the insulating container 1 (i.e., the fixed-side insulating tube 1a). The movable-side external shield 7 extends in the direction of the virtual axis Px so as to cover the movable-side sealing fitting 3 and partially surround the outside of the insulating container 1 (i.e., the movable-side insulating tube 1b).

[0028] Incidentally, with the vacuum valve P (insulating container 1) described above, a triple junction is usually formed at both ends T1 and T2 of the arc shield 5, where the arc shield 5, insulating tubes 1a and 1b, and insulating resin layer Ir are in contact with each other without any gaps.

[0029] In the example shown in Figure 1, the insulating tubes 1a and 1b and the arc shield 5 have a hollow cylindrical shape. Therefore, in the state prior to the addition of the stress relief means 13 described later, the triple point has a continuous circular contour shape (for example, a ring shape) along the circumferential direction with the virtual axis Px as the center.

[0030] With this configuration, for example, if a large internal stress is generated at the triple point due to a rise in temperature, there is a risk of defects such as delamination between the arc shield 5 and the insulating resin layer Ir, or cracks in the insulating resin layer Ir.

[0031] Therefore, in order to prevent such malfunctions from occurring, the vacuum valve P (insulating container 1) of this embodiment is equipped with a stress relief means 13, which makes it possible to relieve the internal stress generated at the triple point (i.e., the boundary portions R1 and R2 described later).

[0032] The constituent requirements for achieving such effects include the arrangement of the stress relaxation means 13, its coefficient of linear expansion (coefficient of thermal expansion), and its material. Below, the arrangement of the stress relaxation means 13 will be explained in detail with reference to Figure 1, and the coefficient of linear expansion (coefficient of thermal expansion) and its material will be explained in detail with reference to Figure 2, which will be discussed later.

[0033] As shown in Figure 1, the stress relief means 13 is interposed between the insulating resin layer Ir, the arc shield 5, and the insulating tubes 1a and 1b. However, with this arrangement, a triple junction point is not formed where the arc shield 5, the insulating tubes 1a and 1b, and the insulating resin layer Ir are in contact with each other without any gaps.

[0034] Therefore, instead of the triple junction, in the vacuum valve P (insulating container 1) of this embodiment, boundary portions R1 and R2 are defined at both ends T1 and T2 of the arc shield 5 where the insulating resin layer Ir, the arc shield 5, and the insulating insulators 1a and 1b are in close proximity to each other.

[0035] These two boundary sections (fixed boundary section R1 and movable boundary section R2) are located at both ends T1 and T2 of the arc shield 5, and each has a continuous circular contour shape (for example, a ring shape) along the circumferential direction with the virtual axis Px as the center. The boundary sections R1 and R2 have contour shapes and positional relationships that coincide with the triple point described above, which was formed in the state prior to the installation of the stress relaxation means 13.

[0036] Figure 2 is a diagram showing the arrangement of the stress relief means 13 at the boundary sections R1 and R2. The stress relief means 13 is configured so that the insulating resin layer Ir, the arc shield 5, and the insulating insulators 1a and 1b do not come into contact with each other at the boundary sections R1 and R2. In other words, the stress relief means 13 is configured so that at least one of the three components consisting of the insulating resin layer Ir, the arc shield 5, and the insulating insulators 1a and 1b does not come into contact with the other components at the boundary sections R1 and R2.

[0037] In Figure 2, as an example, the stress relaxation means 13 is configured such that the insulating resin layer Ir does not come into contact with the arc shield 5 and the insulating tubes 1a and 1b at the boundaries R1 and R2. In other words, the stress relaxation means 13 is configured to separate the insulating resin layer Ir from the arc shield 5 and the insulating tubes 1a and 1b at the boundaries R1 and R2.

[0038] As shown in Figure 2, the stress relief means 13 is continuously provided between the two ends T1 and T2 of the arc shield 5. The outer circumferential surface 5s of the arc shield 5 is formed between these two ends T1 and T2. The stress relief means 13 has a cylindrical shape that matches the contour of the outer circumferential surface 5s so as to completely cover the outer circumferential surface 5s without any gaps. As a result, the stress relief means 13 is positioned adjacent to the boundary portions R1 and R2 defined at the two ends T1 and T2 of the arc shield 5.

[0039] Here, focusing on the materials of the three components adjacent to the boundary R1 and R2 (i.e., insulating tubes 1a and 1b, arc shield 5, and insulating resin layer Ir), we find that they have different coefficients of linear expansion (also called thermal expansion). The coefficient of linear expansion (thermal expansion) is defined as the rate at which the length or volume of an object expands due to a rise in temperature, and its unit is 10⁻¹⁰ -6 It is set to / ℃ (hereinafter referred to as ppm).

[0040] For example, assuming insulating tubes 1a and 1b made of alumina ceramic, their coefficient of linear expansion (coefficient of thermal expansion) is set to 7 ppm. For example, if we consider Arc Shield 5, which is made of a metal material mainly composed of stainless steel, its coefficient of linear expansion (coefficient of thermal expansion) is set to 17 ppm. For example, if we consider an insulating resin layer Ir made of epoxy resin, its coefficient of linear expansion (coefficient of thermal expansion) is set to 18-23 ppm.

[0041] In this case, for example, when the length and volume of these components (insulating tubes 1a, 1b, arc shield 5, insulating resin layer Ir) expand due to a rise in temperature, the expansion rate (also called the linear expansion coefficient) of each component will differ significantly from one another, according to the linear expansion coefficients mentioned above. At this time, the difference in linear expansion between the components will also increase, resulting in large internal stresses being generated at the boundaries R1 and R2.

[0042] Therefore, in order to prevent such malfunctions from occurring, the stress relaxation means 13 is configured to reduce the internal stress generated at the boundary portions R1 and R2 by reducing the difference in linear expansion between the above-mentioned constituent members.

[0043] In addition to the arrangement of the stress relaxation means 13 described above, the linear expansion coefficient (thermal expansion coefficient) of the stress relaxation means 13, as well as its material, are expected to be necessary configuration requirements for achieving such effects.

[0044] First, it is preferable to set the coefficient of linear expansion (thermal expansion coefficient) of the stress relaxation means 13 to be lower than the coefficient of linear expansion (thermal expansion coefficient) of the arc shield 5, and higher than the coefficient of linear expansion (thermal expansion coefficient) of the insulating tubes 1a and 1b.

[0045] Here, if we define the coefficient of linear expansion (coefficient of thermal expansion) as the rate at which the length or volume of an object expands due to a rise in temperature, then the coefficient of linear expansion (coefficient of thermal expansion) of the stress relaxation means 13 should be set so as to satisfy the following relationship.

[0046] That is, letting E1 be the expansion rate of the insulating porcelain tubes 1a, 1b due to temperature rise, E2 be the expansion rate of the stress relaxation means 13 due to temperature rise, and E3 be the expansion rate of the arc shield 5 due to temperature rise, the relationship E1 < E2 < E3 is satisfied.

[0047] As an example satisfying this relationship, assuming that the insulating porcelain tubes 1a, 1b are formed of alumina ceramic, the coefficient of linear expansion (coefficient of thermal expansion) E1 thereof is 7 ppm. Assuming that the arc shield 5 is formed of a metal material containing stainless steel as a main component, the coefficient of linear expansion (coefficient of thermal expansion) E3 thereof is 17 ppm. Therefore, the coefficient of linear expansion (coefficient of thermal expansion) E2 of the stress relaxation means 13 may be set within a range of 7 ppm (=E1) < E2 < 17 ppm (=E3).

[0048] Further, when the coefficient of linear expansion (coefficient of thermal expansion) of the insulating resin layer Ir is considered in this relationship, for example, assuming that the insulating resin layer Ir is formed of epoxy resin, the coefficient of linear expansion (coefficient of thermal expansion) thereof is 18 to 23 ppm. Therefore, letting E4 be the expansion rate of the insulating resin layer Ir due to temperature rise, the relationship E1 < E2 < E3 < E4 only needs to be satisfied.

[0049] Next, as a material for the stress relaxation means 13 having the aforementioned coefficient of linear expansion (coefficient of thermal expansion) E2, the material is preferably an alloy containing at least one metal material selected from among metal materials such as nickel (Ni), copper (Cu), zinc (Zn), silver (Ag), platinum (Pt), and tin (Sn), for example. For example, the alloy is a metal material containing either one of nickel and tin, or a metal material containing both nickel and tin.

[0050] As a method for forming such a metallic stress relaxation means 13 without any gap overall between both ends T1 and T2 of the arc shield 5 (i.e., on the outer peripheral surface 5s), for example, the above-mentioned alloy is adhered to the outer peripheral surface 5s of the arc shield 5 by plating treatment. Then, a metal plating layer formed of a metal film is laminated on the outer peripheral surface 5s of the arc shield 5. Thereby, the metal plating layer containing the above-mentioned alloy (e.g., a nickel plating layer, a tin plating layer) is formed into a film on the outer peripheral surface 5s of the arc shield 5.

[0051] At this time, the film thickness (i.e., thickness) of the metal plating layer formed on the outer peripheral surface 5s of the arc shield 5 may be set such that the thickness of the metal plating layer is 0.1 to 2%, preferably 0.3 to 1%, relative to the thickness of the arc shield 5.

[0052] In this case, if the thickness of the stress relaxation means 13 is W1, the thickness of the arc shield 5 is W2, and the thickness W2 is set to 100%, it is only necessary to satisfy the relationship W2×0.1% ≦ W1 ≦ W2×2%. More preferably, it is only necessary to satisfy the relationship W2×0.3% ≦ W1 ≦ W2×1%.

[0053] Here, as an example of the stress relaxation means 13 formed into a film on the outer peripheral surface 5s of the arc shield 5, a nickel plating layer or a tin plating layer is assumed. The coefficient of linear expansion (coefficient of thermal expansion) of the nickel plating layer is 12 to 17 ppm (=E2), and the coefficient of linear expansion (coefficient of thermal expansion) of the tin plating layer is 11.6 ppm (=E2), both of which satisfy the relationship 7 ppm (=E1) < E2 < 17 ppm (=E3).

[0054] It should be noted that, although the manufacturing method of the insulating container 1 was not mentioned in the above embodiment, as an example of the manufacturing method, after forming the above-mentioned stress relaxation means 13 into a film on the outer peripheral surface 5s of the arc shield 5, insulating porcelain tubes 1a and 1b may be connected to both ends T1 and T2 of the arc shield 5 (e.g., by silver brazing).

[0055] Figure 3 is a diagram showing the arrangement of the stress relief means 13 at the boundary portions R1 and R2. In the above-described embodiment, an insulating container 1 was assumed in which the cylindrical surface 13s of the stress relief means 13 laminated on the outer surface 5s of the arc shield 5 is recessed radially inward (indented, recessed) compared to the outer surfaces Sa and Sb of the insulating tubes 1a and 1b. However, instead, as shown in Figure 3, the cylindrical surface 13s of the stress relief means 13 and the outer surfaces Sa and Sb of the insulating tubes 1a and 1b may be configured to have the same diameter (i.e., be flush) with each other. An insulating container 1 having such a configuration is also included in the technical scope of the present invention and can obtain the same effects as the above-described embodiment.

[0056] As described above, according to this embodiment, at the boundary portions R1 and R2 where the insulating resin layer Ir, the arc shield 5, and the insulating insulator tubes 1a and 1b are in close proximity, a stress relaxation means 13 is interposed between these components (insulating insulator tubes 1a and 1b, the arc shield 5, and the insulating resin layer Ir) with a coefficient of linear expansion (coefficient of thermal expansion) set to be lower than that of the arc shield 5 and higher than that of the insulating insulator tubes 1a and 1b. This makes it possible to reduce the difference in linear expansion between the components, and as a result, the internal stress generated at the boundary portions R1 and R2 can be relaxed. Thus, the occurrence of defects such as peeling and cracking of the insulating resin layer Ir is prevented, and for example, ground fault accidents due to partial discharge during the operation of the vacuum valve P (especially when voltage is applied) can be avoided.

[0057] According to this embodiment, as an example of the stress relaxation means 13, a vacuum valve P (product of the present invention) in which a nickel plating layer is deposited on the outer surface 5s of the arc shield 5 (for example, 5 μm or more (preferably 10 μm or more)) and a vacuum valve (conventional product) in which the stress relaxation means 13 (nickel plating layer) is not deposited were prepared, and a comparative test of partial discharge was performed when a voltage of 60 kV was applied. As a result, in the conventional product, the occurrence of partial discharge at the triple point described above was confirmed, and it is considered that a large internal stress was generated at the triple point, which led to the occurrence of defects such as peeling and cracking of the insulating resin layer. In contrast, in the product of the present invention, the occurrence of partial discharge at the boundary portions R1 and R2 described above was not confirmed, and it is considered that a large internal stress was not generated at the boundary portions R1 and R2, thereby preventing the occurrence of defects such as peeling and cracking of the insulating resin layer Ir.

[0058] "Second Embodiment" Figure 4 shows the main structure of the vacuum valve P according to the second embodiment. In the first embodiment described above, a structure was described in which the insulating resin layer Ir is in direct contact with the surface 13s of the stress relaxation means 13, but in this embodiment, a structure is assumed in which a chemical coupling layer 13p is interposed between the surface 13s of the stress relaxation means 13 and the insulating resin layer Ir.

[0059] Since the other structures are the same as those of the first embodiment described above, the chemical coupling layer 13p, which is the main structure of this embodiment, will be described in detail below, and the explanation of the other structures will be omitted.

[0060] As shown in Figure 4, the stress relaxation means 13 of this embodiment includes a chemical coupling layer 13p. The chemical coupling layer 13p is formed on the surface 13s of the stress relaxation means 13 by a chemical coupling treatment. The chemical coupling layer 13p has functional groups that are highly reactive with the insulating resin layer Ir. As a result, the chemical coupling layer 13p improves the adhesion between the surface 13s of the stress relaxation means 13 and the insulating resin layer Ir.

[0061] In the example shown in Figure 4, a nickel plating layer is assumed as the stress relaxation means 13 to be deposited on the outer surface 5s of the arc shield 5. A silane coupling layer is assumed as the chemical coupling layer 13p. And the insulating resin layer Ir is assumed to be made of epoxy resin.

[0062] In this case, the surface 13s of the nickel plating layer 13 is subjected to an existing silane coupling treatment to form a silane coupling layer 13p. This causes the silane compound to bond to the OH layer of the nickel plating. As a result, functional groups that are highly reactive with the epoxy resin Ir are applied to the surface 13s of the nickel plating layer 13. Consequently, the adhesion between the surface 13s of the stress relaxation means 13 and the insulating resin layer Ir can be strengthened via the silane coupling layer 13p.

[0063] Figure 5 is a chart showing the formation process of the silane coupling layer 13p. As shown in Figure 5, first, a silane coupling treatment is performed on the surface 13s of the stress relaxation means 13 that has been deposited on the outer peripheral surface 5s of the arc shield 5 (F1). At this time, a silane compound is applied to the surface 13s of the stress relaxation means 13. Next, a heat treatment is performed on this silane compound (F2). As a result, the silane coupling layer 13p is formed on the surface 13s of the stress relaxation means 13 (F3). Then, an insulating resin layer Ir is molded to cover the outside of the insulating container 1 without any gaps, including this silane coupling layer 13p (F4). As a result, the vacuum valve P described above is manufactured.

[0064] Figure 6 shows the results of comparing the adhesive strength between the stress relaxation means 13 and the insulating resin layer Ir with and without the silane coupling treatment described above. Here, in the adhesive strength comparison test, a test piece having the laminated structure shown in Figure 4 is prepared. Then, for example, with the arc shield 5 side fixed, a tensile force is applied to the insulating resin layer Ir side.

[0065] The tensile force is applied in a direction that separates the insulating resin layer Ir from the arc shield 5. At this time, a tensile force of 5 mm per second (5 mm / sec) is applied until the test specimen breaks. As shown in Figure 6, it was found that the specimen with silane coupling treatment has approximately five times the adhesive strength compared to the specimen without silane coupling treatment.

[0066] As described above, according to this embodiment, even in the case of vacuum valves P in power distribution equipment for railways or furnaces, which are opened and closed frequently, the adhesive force between the surface 13s of the stress-relieving means 13 and the insulating resin layer Ir can be strengthened by interposing the silane coupling layer 13p between the surface 13s of the stress-relieving means 13 and the insulating resin layer Ir.

[0067] This ensures that defects such as peeling and cracking of the insulating resin layer Ir are reliably prevented, even in operating environments where mechanical fatigue due to frequent opening and closing operations continues over a long period of time. Note that the other configurations and effects are the same as those of the first embodiment described above, and therefore their explanation is omitted.

[0068] "First Variation" Figure 7 is a diagram showing the arrangement of the stress relief means 13 according to the first modified example. In the embodiments described above, the stress relief means 13 was assumed to be continuously provided between the two ends T1 and T2 of the arc shield 5. However, in this modified example, the stress relief means 13 is provided intermittently at both ends T1 and T2 of the arc shield 5. In the example in Figure 7, the stress relief means 13 is arranged adjacent to the boundary portions R1 and R2 so as to partially cover the outer circumferential surface 5s of the arc shield 5.

[0069] As shown in Figure 7, the stress relief means 13 is positioned in contact with (abuts against) the outer surface 5s of the arc shield 5 at the boundary portions R1 and R2. This configuration ensures that the stress relief means 13 does not come into contact with the insulating resin layer Ir, the arc shield 5, and the insulating tubes 1a and 1b simultaneously at the boundary portions R1 and R2.

[0070] In Figure 7, as an example, the stress relaxation means 13 is configured such that the insulating resin layer Ir does not come into contact with the arc shield 5 and insulating tubes 1a and 1b at the boundaries R1 and R2. Note that the other configurations and effects are the same as those described in the embodiments above, and therefore their explanation is omitted.

[0071] "Second variation" Figure 8 is a diagram showing the arrangement of the stress relief means 13 according to the second modified example. In the embodiments described above, the stress relief means 13 was assumed to be continuously provided between the two ends T1 and T2 of the arc shield 5. However, in this modified example, the stress relief means 13 is provided intermittently at both ends T1 and T2 of the arc shield 5. In the example in Figure 8, the stress relief means 13 is arranged adjacent to the boundary portions R1 and R2 so as to partially cover the outer circumferential surface 5s of the arc shield 5.

[0072] As shown in Figure 8, the stress relief means 13 is embedded (recessed) into the outer surface 5s of the arc shield 5 at the boundary portions R1 and R2. This configuration ensures that the stress relief means 13 does not come into contact with the insulating resin layer Ir, the arc shield 5, and the insulating tubes 1a and 1b simultaneously at the boundary portions R1 and R2.

[0073] In Figure 8, as an example, the stress relaxation means 13 is configured so that the arc shield 5 does not come into contact with the insulating resin layer Ir and the insulating tubes 1a and 1b at the boundaries R1 and R2. Note that the other configurations and effects are the same as those described in the embodiments above, and therefore their explanation is omitted.

[0074] "Third Variation" Figure 9 is a diagram showing the arrangement of the stress relief means 13 according to the third modified example. In the embodiments described above, the stress relief means 13 was assumed to be continuously provided between the two ends T1 and T2 of the arc shield 5. However, in this modified example, the stress relief means 13 is provided intermittently at both ends T1 and T2 of the arc shield 5. In the example in Figure 9, the stress relief means 13 is arranged adjacent to the boundary portions R1 and R2 without covering the outer circumferential surface 5s of the arc shield 5.

[0075] As shown in Figure 9, the stress relief means 13 is embedded (recessed) into the insulating tubes 1a and 1b at the boundary portions R1 and R2. This configuration ensures that the stress relief means 13 does not come into contact with the insulating resin layer Ir, the arc shield 5, and the insulating tubes 1a and 1b simultaneously at the boundary portions R1 and R2.

[0076] In Figure 9, as an example, the stress relaxation means 13 is configured such that the insulating tubes 1a and 1b do not come into contact with the arc shield 5 and the insulating resin layer Ir at the boundary sections R1 and R2. Note that the other configurations and effects are the same as those described in the embodiments above, and therefore their explanation is omitted.

[0077] "Fourth variation" Figure 10 is a diagram showing the arrangement of the stress relief means 13 according to the fourth modified example. In the embodiments described above, the stress relief means 13 was assumed to be continuously provided between the two ends T1 and T2 of the arc shield 5. However, in this modified example, the stress relief means 13 is provided intermittently at the two ends T1 and T2 of the arc shield 5. In the example shown in Figure 10, the insulating resin layer Ir, the arc shield 5, and the insulating insulators 1a and 1b are arranged to overlap the boundary portions R1 and R2 so as to simultaneously separate them from the boundary portions R1 and R2. As shown in Figure 10, the stress relief means 13 has a contour shape that is expanded, for example, in a rectangular cross-section around the boundary portions R1 and R2, and a part of its outer region is positioned to penetrate (protrude) into the insulating resin layer Ir, the arc shield 5, and the insulating insulators 1a and 1b. In this way, the stress relief means 13 is configured so that the insulating resin layer Ir, the arc shield 5, and the insulating insulators 1a and 1b do not come into contact simultaneously at the boundary portions R1 and R2. The other configurations and effects are the same as those of the embodiments described above, so their explanation will be omitted.

[0078] Although various embodiments and some modifications of the present invention have been described above, these embodiments and modifications are presented as examples only and are not intended to limit the scope of the invention. These embodiments and modifications can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and modifications are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0079] P...Molded vacuum valve, E1...Fixed electrode, E2...Movable electrode, 1...Insulating container, 1a...Fixed side insulating tube, 1b...Movable side insulating tube, Sa,Sb...Outer surface, 2...Fixed side sealing fitting, 3...Movable side sealing fitting, 4...Airtightness maintenance mechanism, 5...Arc shield, 5s...Outer surface, 6...Fixed side external shield, 7...Movable side external shield, 8...Fixed contact, 9...Fixed current carrying shaft, 10...Movable contact, 11...Movable current carrying shaft, 12...Grounding layer, 13...Stress relief means, 13s...Surface, Ir...Insulating resin layer, R1...Fixed side boundary, R2...Movable side boundary.

Claims

1. A cylindrical insulating container that houses a pair of electrodes so as to be able to move them apart, and has openings at both ends in the direction in which the electrodes move apart and apart, An insulating resin layer molded to cover the outside of the insulating container, The insulating container is provided with a cylindrical arc shield that extends along the direction of separation so as to surround the pair of electrodes, The aforementioned insulating container is In the aforementioned separation direction, cylindrical insulating tubes are connected to both ends of the arc shield, The device comprises a stress-relieving means for relieving stress generated at the boundary where the insulating resin layer, the arc shield, and the insulating insulator tube are in close proximity to each other, The stress relief means is a molded vacuum valve made of a metallic material containing either nickel or tin, or a metallic material containing both nickel and tin.

2. The molded vacuum valve according to claim 1, wherein the stress-relieving means is interposed between the insulating resin layer, the arc shield, and the insulating insulator tube at the boundary portion so that the insulating resin layer, the arc shield, and the insulating insulator tube do not come into contact with each other at the same time.

3. The molded vacuum valve according to claim 2, wherein the stress relief means is configured such that at least one of the three components, consisting of the insulating resin layer, the arc shield, and the insulating insulator tube, does not come into contact with the other components.

4. The molded vacuum valve according to claim 3, wherein the stress relief means is provided between the two ends of the arc shield and is arranged adjacent to the boundary so as to cover the entire outer surface of the arc shield.

5. The molded vacuum valve according to claim 3, wherein the stress relief means are provided at both ends of the arc shield and are arranged adjacent to the boundary so as to partially cover the outer surface of the arc shield.

6. The molded vacuum valve according to claim 3, wherein the stress relief means are provided at both ends of the arc shield and are arranged adjacent to the boundary without covering the outer surface of the arc shield.

7. The molded vacuum valve according to claim 3, wherein the stress relief means are provided at both ends of the arc shield and are arranged to overlap the boundary portion such that the insulating resin layer, the arc shield, and the insulating insulator tube are simultaneously separated from the boundary portion.

8. Let E1 be the rate at which the insulating tube expands due to the rise in temperature. Let E2 be the rate at which the stress-relieving means expands due to the rise in temperature. If E3 is the rate at which the arc shield expands due to the temperature rise, E1 < E2 < E3 A molded vacuum valve according to claim 1 that satisfies the relationship.

9. If E4 is the rate at which the insulating resin layer expands due to temperature rise, E1<E2<E3<E4 A molded vacuum valve according to claim 8 that satisfies the relationship.

10. Let W1 be the thickness of the stress-relieving means. If the thickness of the arc shield is set to W2, and the thickness W2 is set to 100%, W2 × 0.1% ≤ W1 ≤ W2 × 2% A molded vacuum valve according to claim 1 that satisfies the relationship.

11. Let W1 be the thickness of the stress-relieving means. If the thickness of the arc shield is set to W2, and the thickness W2 is set to 100%, W2 × 0.3% ≤ W1 ≤ W2 × 1% A molded vacuum valve according to claim 1 that satisfies the relationship.

12. In a configuration in which the insulating resin layer is brought into contact with the surface of the stress relaxation means, The stress relaxation means includes a chemical coupling layer formed on the surface by a chemical coupling treatment and having reactivity with the insulating resin layer. The molded vacuum valve according to claim 1, wherein the chemical coupling layer improves the adhesion between the surface of the stress-relieving means and the insulating resin layer.

Images