DC HIGH-VOLTAGE RELAY, AND CONTACT MATERIAL FOR DC HIGH-VOLTAGE RELAY

Abstract

A DC high-voltage relay with at least one contact pair including a movable contact and a fixed contact, the contact pair having a contact force and/or an opening force of 100 gf or more, having a rated voltage of 48 V or more, the movable contact and/or the fixed contact includes a Ag oxide-based contact material. Metal components contain at least one metal M essentially containing Zn, and a balance being Ag and inevitable impurity metals, and the contact material has a content of the metal M of 0.2% by mass or more and 8% by mass or less based on a total mass. The contact material has a material structure in which one or more oxides of the metal M having an average particle size of 0.01 μm or more and 0.4 μm or less are dispersed in a matrix including Ag or a Ag alloy.

Claims

1. A DC high-voltage relay comprising at least one contact pair comprising a movable contact and a fixed contact, the contact pair having a contact force and/or an opening force of 100 gf or more, the DC high-voltage relay having a rated voltage of 48 V or more, wherein the movable contact and/or the fixed contact comprises a Ag oxide-based contact material, metal components in the contact material comprises at least one metal M essentially containing Zn, and a balance being Ag and inevitable impurity metals, the contact material has a content of the metal M of 0.2% by mass or more and 8% by mass or less based on a total mass of all metal components of the contact material, the contact material has a material structure in which one or more oxides of the metal M are dispersed in a matrix including Ag or a Ag alloy, and the oxides have an average particle size of 0.01 μm or more and 0.4 μm or less.

2. The DC high-voltage relay according to claim 1, wherein the contact material further contains at least one of Sn, In, Ni, Te, Bi and Cu as the metal M, and the content of the metal M is 0.2% by mass or more and 8.0% by mass or less based on the total mass of all the metal components of the contact material.

3. The DC high-voltage relay according to claim 1, comprising: a drive section which generates and transmits a drive force for moving a movable contact; and a contact section which performs switching of a DC high-voltage circuit, the drive section comprises an electromagnet or a coil which generates a drive force; a transmission unit which transmits the drive force to the contact section; and a biasing unit which biases the transmission unit for closing or opening the contact pair, the contact section comprises at least one contact pair including a fixed contact and a movable contact which is moved by the transmission unit of the drive section; and at least one movable terminal bonded to the movable contact and at least one fixed terminal bonded to the fixed contact.

4. The DC high-voltage relay according to claim 1, wherein oxides on an arbitrary cross-section of the contact material has an area ratio of 0.1% or more and 20% or less.

5. A contact material for a DC high-voltage relay, the contact material being a Ag oxide-based contact material for forming at least a surface of a movable contact and/or a fixed contact of a DC high-voltage relay, the DC high-voltage relay having a rated voltage of 48 V or more, and a contact force and/or an opening force of 100 gf or more at a contact pair, wherein metal components in the contact material comprise at least one metal M essentially containing Zn, and a balance being Ag and inevitable impurity metals, the contact material has a content of the metal M of 0.2% by mass or more and 8% by mass or less based on a total mass of all metal components of the contact material, the contact material has a material structure in which one or more oxides of the metal M are dispersed in a matrix including Ag or a Ag alloy, and the oxides have an average particle size of 0.01 μm or more and 0.4 μm or less.

6. The contact material for a DC high-voltage relay according to claim 5, wherein at least one of Sn, In, Ni, Te, Bi and Cu is further contained as the metal M, and the content of the metal M is 0.2% by mass or more and 8% by mass or less based on the total mass of all the metal components of the contact material.

7. The contact material for a DC high-voltage relay according to claim 5, wherein an area ratio of the oxides on an arbitrary cross-section is 0.1% or more and 20% or less.

8. The DC high-voltage relay according to claim 2, comprising: a drive section which generates and transmits a drive force for moving a movable contact; and a contact section which performs switching of a DC high-voltage circuit, the drive section comprises an electromagnet or a coil which generates a drive force; a transmission unit which transmits the drive force to the contact section; and a biasing unit which biases the transmission unit for closing or opening the contact pair, the contact section comprises at least one contact pair including a fixed contact and a movable contact which is moved by the transmission unit of the drive section; and at least one movable terminal bonded to the movable contact and at least one fixed terminal bonded to the fixed contact.

9. The DC high-voltage relay according to claim 2, wherein oxides on an arbitrary cross-section of the contact material has an area ratio of 0.1% or more and 20% or less.

10. The DC high-voltage relay according to claim 3, wherein oxides on an arbitrary cross-section of the contact material has an area ratio of 0.1% or more and 20% or less.

11. The contact material for a DC high-voltage relay according to claim 6, wherein an area ratio of the oxides on an arbitrary cross-section is 0.1% or more and 20% or less.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0096] FIG. 1 is a diagram showing an example of a configuration (double-break structure) of a plunger-type DC high-voltage relay.

[0097] FIG. 2 is a diagram showing an example of a configuration of a hinge-type DC high-voltage relay.

[0098] FIG. 3 is a diagram showing a circuit used in a capacitor load durability test in a third embodiment.

DESCRIPTION OF EMBODIMENTS

[0099] Hereinafter, an embodiment of the present invention will be described. In this embodiment, not only Ag—ZnO-based contact materials in which Zn alone was added as metal M but also Ag—ZnO-based contact materials in which Sn was added in addition to Zn were manufactured, and structure observation and hardness measurement were performed. The manufactured Ag oxide-based contact materials were incorporated as contacts in a DC high-voltage relay, and the properties of the contact materials were evaluated. Ag oxide-based contact materials in which Sn and the like were added without containing Zn were also manufactured and evaluated as comparative examples.

[0100] First Embodiment: In this embodiment, various Ag oxide-based contact materials were manufactured by an internal oxidation method and a powder metallurgy method, material properties were examined, DC high-voltage relays (contact force/opening force: 75 gf/125 gf) were then manufactured to check an operation (interruption durability) and measure an arc discharge property and contact resistance.

[0101] In the manufacture of the contact material by the internal oxidation method, ingots of Ag alloys having various compositions were cast by melt casting in a high-frequency melting furnace. After the melt casting, each ingot was formed into pieces of 3 mm or less, and the pieces were internally oxidized. In the internal oxidation, the oxygen partial pressure and the heating temperature were adjusted in ranges of 0.2 to 0.9 MPa and 500° C. to 900° C., respectively. Next, the internally oxidized pieces were collected and compression-molded to form a billet having a diameter of 50 mm. The billets were subjected to hot extrusion processing, and subsequently subjected to drawing processing to obtain a wire rod having a diameter of 2.3 mm, and a rivet-type contact material was manufactured with a header machine.

[0102] In manufacturing of the contact material by the powder metallurgy method, Ag powder and oxide powder (each having an average particle size of 0.5 to 100 μm) were mixed, and compression-molded to form billets having a diameter of 50 mm.

[0103] The billet was sintered, and then subjected to cold compression processing twice and sintering processing twice, and subsequently to hot compression processing to obtain a sintered body. In the sintering step performed a plurality of times, the heating temperature was set to 800° C. to 850° C. for performing heating in this temperature range for the sintering. Besides, in the cold compression processing performed after the sintering, a load employed in the second processing was set to be double of that in the first processing. Thereafter, the sintered body was subjected to hot extrusion processing, and subsequently subjected to drawing processing to obtain a wire rod having a diameter of 2.3 mm, and a rivet-type contact material was manufactured therefrom with a header machine.

[0104] In this embodiment, two rivet-type contact materials, with one for a movable contact and the other for a fixed contact, were manufactured. The size of a head portion of the movable contact was set to a diameter of 3.15 mm and a height of 0.75 mm, and the size of a head portion of the fixed contact was set to a diameter of 3.3 mm and a height of 1.0 mm.

[Hardness Measurement of Contact Material]

[0105] In a process for manufacturing the contact materials, a wire sample was cut out from the wire rod subjected to drawing processing and annealed (temperature: 700° C.), and the hardness was measured. For hardness measurement, the sample was embedded in a resin, exposure polishing was performed so as to expose a lateral cross-section (cross-section in a short side direction), and the hardness was measured with a Vickers hardness meter (HMV-G21ST manufactured by Shimadzu Corporation). For measurement conditions, the load was set to 200 gf, measurement was performed at five positions, and an average for the measurements was defined as a hardness value.

[0106] Tables 1 and 2 show the compositions and the hardness values of the contact materials of Examples (Examples 1 to 49) and Comparative Examples (Comparative Examples 1 to 23) manufactured in this embodiment. In this embodiment, a contact material containing pure Ag not containing oxide particles was also manufactured and evaluated (Comparative Example 23). This Ag contact was manufactured by hot-extruding the melted and cast billets and performing processing etc. The hardness of the Ag contact was measured with a sample cut out after the Ag wire rod was annealed (temperature: 700° C.), and then subjected to drawing processing at a processing rate of 4.2%.

[Structure Observation of Contact Material]

[0107] Next, the structures of the contact materials were observed. A transverse section of a sample embedded in a resin as in hardness measurement was observed with an electron microscope (SEM) (magnification of 5000 times). The formed SEM image was subjected to image processing by the use of particle analysis software. In the image processing, the total area (area ratio to the visual field area), the average particle size and the particle size distribution of oxides were measured and analyzed as a dispersion state of the oxides in the contact material. For the analysis, Particle Analysis System AZtecFeature made by Oxford Instruments was used. The particle size was determined in terms of an equivalent circular diameter (areal equivalent circular diameter). Based on the area f of each oxide particle, the particle size of the oxide particle was calculated from an equivalent circular diameter calculation formula ((4f/π).sup.1/2), and the average and the standard deviation a of the particle sizes were determined.

[0108] Tables 1 and 2 show the compositions, the hardness values and measurement results of dispersion states of the oxide particles of the contact materials of Examples (Examples 1 to 49) and Comparative Examples (Comparative Examples 1 to 23) manufactured in this embodiment. From these tables, it is confirmed that fine oxide particles are dispersed in a Ag matrix in the contact material of each example.

TABLE-US-00001 TABLE 1 Dispersion state of oxide particles Particle size Content Average standard of metal Area particle deviation Composition (mass %)*.sup.1 M ratio size δ Hardness Manufacture Ag Zn Sn In Ni Te Bi Cu Mg (mass %) (%) (μm) (μm) (Hv) method Ex. 1 Balance 0.20 — — — — — — — 0.20 0.39 0.04 0.01 74 Internal oxidation Ex. 2 1.00 — — — — — — — 1.00 2.26 0.05 0.02 94 Internal oxidation Ex. 3 2.50 — — — — — — — 2.50 6.89 0.06 0.06 89 Internal oxidation Ex. 4 5.00 — — — — — — — 5.00 11.98 0.08 0.11 77 Internal oxidation Ex. 5 6.00 — — — — — — — 6.00 15.19 0.10 0.15 86 Internal oxidation Ex. 6 6.50 — — — — — — — 6.50 14.90 0.29 0.27 86 Powder metallurgy Ex. 7 8.00 — — — — — — — 8.00 19.48 0.11 0.13 90 Internal oxidation Ex. 8 0.60 0.40 — — — — — — 1.00 2.06 0.07 0.04 119 Internal oxidation Ex. 9 2.40 1.60 — — — — — — 4.00 8.75 0.05 0.02 138 Internal oxidation Ex. 10 4.80 3.20 — — — — — — 8.00 17.64 0.18 0.17 79 Powder metallurgy Ex. 11 0.20 — — — — — — — 0.20 0.74 0.15 0.12 44 Powder metallurgy Ex. 12 3.00 — — — — — — — 3.00 7.53 0.06 0.04 101 Internal oxidation Ex. 13 0.33 0.67 — — — — — — 1.00 1.15 0.05 0.02 109 Internal oxidation Ex. 14 1.50 0.50 — — — — — — 2.00 3.10 0.07 0.05 130 Internal oxidation Ex. 15 1.00 1.00 — — — — — — 2.00 4.91 0.07 0.04 101 Internal oxidation Ex. 16 0.30 1.70 — — — — — — 2.00 2.02 0.05 0.03 117 Internal oxidation Ex. 17 3.90 0.10 — — — — — — 4.00 8.04 0.05 0.02 126 Internal oxidation Ex. 18 3.00 1.00 — — — — — — 4.00 9.19 0.05 0.02 144 Internal oxidation Ex. 19 2.00 2.00 — — — — — — 4.00 9.04 0.19 0.15 69 Powder metallurgy Ex. 20 1.40 2.60 — — — — — — 4.00 8.93 0.09 0.05 115 Internal oxidation Ex. 21 0.60 3.40 — — — — — — 4.00 8.51 0.07 0.04 110 Internal oxidation Ex. 22 6.00 2.00 — — — — — — 8.00 18.80 0.22 0.20 77 Powder metallurgy Ex. 23 4.00 4.00 — — — — — — 8.00 19.08 0.17 0.15 87 Powder metallurgy Ex. 24 2.70 5.30 — — — — — — 8.00 15.03 0.15 0.14 85 Powder metallurgy Ex. 25 1.00 7.00 — — — — — — 8.00 17.90 0.15 0.11 92 Powder metallurgy Ex. 26 0.30 7.70 — — — — — — 8.00 15.28 0.14 0.09 91 Powder metallurgy Ex. 27 0.50 — 0.10 — — — — — 0.60 1.68 0.07 0.08 106 Internal oxidation Ex. 28 1.50 — 0.50 — — — — — 2.00 4.11 0.07 0.06 134 Internal oxidation Ex. 29 1.00 — 1.00 — — — — — 2.00 3.39 0.09 0.10 144 Internal oxidation Ex. 30 3.90 — 0.10 — — — — — 4.00 11.14 0.06 0.03 120 Internal oxidation Ex. 31 3.00 — 1.00 — — — — — 4.00 11.34 0.06 0.02 118 Internal oxidation Ex. 32 2.00 — 2.00 — — — — — 4.00 8.99 0.05 0.02 144 Internal oxidation Ex. 33 6.00 — 2.00 — — — — — 8.00 19.93 0.20 0.19 79 Powder metallurgy Ex. 34 4.00 — 4.00 — — — — — 8.00 17.55 0.25 0.24 78 Powder metallurgy Ex. 35 4.00 — 4.00 — — — — — 8.00 17.74 0.18 0.18 78 Powder metallurgy Ex. 36 2.00 — 6.00 — — — — — 8.00 18.07 0.17 0.19 76 Powder metallurgy Ex. 37 0.50 — — 0.50 — — — — 1.00 3.76 0.10 0.11 51 Powder metallurgy Ex. 38 7.90 — — 0.10 — — — — 8.00 17.64 0.09 0.13 92 Internal oxidation Ex. 39 6.80 — — 1.20 — — — — 8.00 17.11 0.23 0.21 74 Powder metallurgy Ex. 40 0.50 — — — 0.50 — — — 1.00 0.99 0.04 0.03 60 Internal oxidation Ex. 41 7.90 — — — 0.10 — — — 8.00 18.63 0.08 0.09 111 Internal oxidation Ex. 42 0.50 — — — — 0.50 — — 1.00 1.73 0.07 0.05 53 Internal oxidation Ex. 43 7.90 — — — — 0.10 — — 8.00 17.61 0.33 0.47 77 Internal oxidation Ex. 44 5.70 0.10 0.10 0.10 — — — — 6.00 6.82 0.14 0.08 40 Internal oxidation Ex. 45 5.60 0.10 0.10 0.10 0.10 — — — 6.00 13.93 0.06 0.05 116 Internal oxidation Ex. 46 5.80 0.10 — — — 0.10 — — 6.00 13.70 0.07 0.06 96 Internal oxidation Ex. 47 4.50 — — — 1.50 — — — 6.00 12.66 0.07 0.08 102 Internal oxidation Ex. 48 3.40 — — — — — 3.40 — 6.80 14.17 0.09 0.14 96 Internal oxidation Ex. 49 6.00 — — — — — — — 6.00 13.61 0.25 0.25 66 Powder metallurgy *.sup.1Concentration based on all metal components.

TABLE-US-00002 TABLE 2 Dispersion state of oxide particles Particle size Content Average standard of metal Area particle deviation Composition (mass %)*.sup.1 M ratio size δ Hardness Manufacture Ag Zn Sn In Ni Te Bi Cu Mg (mass %) (%) (μm) (μm) (Hv) method Comp. Balance — 3.60 1.30 0.10 — — — — 5.00 6.49 0.04 0.04 106 Internal Ex. 1 oxidation Comp. — 3.30 1.30 0.10 0.30 — — — 5.00 8.17 0.06 0.06 95 Internal Ex. 2 oxidation Comp. — 5.90 1.90 0.20 — — — — 8.00 14.52 0.16 0.10 110 Internal Ex. 3 oxidation Comp. — 6.40 2.50 0.10 1.00 — — — 10.00 19.10 0.14 0.18 91 Internal Ex. 4 oxidation Comp. 10.80  — — — — — — — 10.80 23.78 0.16 0.21 86 Internal Ex. 5 oxidation Comp. 0.10 — — — — — — — 0.10 0.24 0.05 0.03 60 Internal Ex. 6 oxidation Comp. 0.10 — — — — — — — 0.10 0.50 0.15 0.13 43 Powder Ex. 7 metallurgy Comp. 11.00  — — — — — — — 11.00 22.41 0.32 0.27 80 Powder Ex. 8 metallurgy Comp. 0.30 9.00 — — — — — — 9.30 17.25 0.14 0.09 100 Powder Ex. 9 metallurgy Comp. 0.50 — — — 1.50 — — — 2.00 13.93 1.27 2.27 107 Internal Ex. 10 oxidation Comp. 3.50 — — — 2.50 — — — 6.00 17.56 0.56 1.40 48 Powder Ex. 11 metallurgy Comp. 0.50 — — — — 1.50 — — 2.00 8.16 0.52 0.67 46 Powder Ex. 12 metallurgy Comp. 4.50 — — — — 1.50 — — 6.00 18.48 0.53 0.86 54 Internal Ex. 13 oxidation Comp. 3.50 — — — — 2.50 — — 6.00 17.84 0.62 0.86 51 Powder Ex. 14 metallurgy Comp. — 0.20 — — — — — — 0.20 0.09 0.04 0.07 81 Internal Ex. 15 oxidation Comp. — 1.00 — — — — — — 1.00 0.41 0.05 0.05 100 Internal Ex. 16 oxidation Comp. — 3.00 — — — — — — 3.00 7.54 0.07 0.03 108 Internal Ex. 17 oxidation Comp. — 6.00 — — — — — — 6.00 12.59 0.09 0.06 117 Internal Ex. 18 oxidation Comp. — 5.00 1.00 — — — — — 6.00 14.27 0.09 0.09 114 Internal Ex. 19 oxidation Comp. — 5.90 — — — 0.10 — — 6.00 10.83 0.09 0.07 114 Internal Ex. 20 oxidation Comp. — 8.00 — — — — — — 8.00 15.54 0.17 0.14 100 Powder Ex. 21 metallurgy Comp. 6.00 — — — — — — — 6.00 19.06 0.44 0.53 64 Powder Ex. 22 metallurgy Comp. 100 — — — — — — — — 0.00 — — — 50 Melting Ex. 23 *.sup.1Concentration based on all metal components.

[0109] [Evaluation of Interruption Durability of DC High-Voltage Relay]

[0110] DC high-voltage relays in which the contact materials of the examples and the comparative examples were respectively incorporated were manufactured, and the interruption durability of these relays were checked. Here, relays of the same type as in FIG. 1, which had a double-break structure, were prepared, and rivet-type contacts formed of the contact materials were bonded to movable terminals and fixed terminals of the relays (two contact pairs were formed from a total of four contacts). Regarding the size of the contact (size of the head portion of the rivet), the movable contact has a diameter of 3.15 mm and a thickness of 0.75 mm (the area of a contact surface in observation of the head portion from the upper surface is 7.79 mm.sup.2), and the fixed contact has a diameter of 3.3 mm and a thickness of 1.0 mm (the area of a contact surface in observation of the head portion from the upper surface is 8.55 mm.sup.2). Arc-extinguishing magnets (two neodymium magnets having a magnetic flux density of 200 mT and containing neodymium, that is, a rare earth element) were disposed on the periphery of the movable contact and the fixed contact. The magnetic flux density at the central position in contacting of the contacts was 26 mT as measured with a gaussmeter.

[0111] In this embodiment, the operation conditions for the DC high-voltage relay were set as follows: voltage/current: DC 360 V/400 A, and contact force/opening force of movable contact: 75 gf/125 gf. The setting of the contact force was adjusted by the strength of a contact pressure spring, and the setting of the opening force was adjusted by the strength of a restoration spring. The DC high-voltage relay used for this evaluation test had a double-break structure, ½ of the force exerted on each contact pairs by the contact pressure spring and the restoration spring was defined as the contact force and the opening force.

[0112] In the evaluation of interruption durability of the DC high-voltage relay of the present embodiment, a switching operation of the contacts was performed 10 times, and it was confirmed whether or not the contacts were welded after each switching operation. A relay in which the contacts were not welded after performing the switching operation 10 times was evaluated as acceptable (o), and a relay in which the contacts were welded before performing the switching operation 10 times was evaluated as unacceptable (x).

[0113] [Evaluation of Arc Discharge Property in DC High-Voltage Relay]

[0114] Next, DC high-voltage relays in which the contact materials of the examples and comparative examples were respectively incorporated were manufactured, and an evaluation test for an arc discharge property of contacts was performed. Relays having a double-break structure similarly to those described above were prepared, and rivet-type contacts formed of the contact materials were bonded to movable terminals and fixed terminals of the relays. The size of the contacts and the magnetic flux density of arc-extinguishing magnets were the same as those described above.

[0115] In the evaluation test for an arc discharge property of the DC high-voltage relay performed in the present embodiment, a switching operation of the contacts was performed under conditions: voltage/current: DC 360 V/400 A, and the contact force/opening force of movable contact: 75 gf/125 gf, and an arc discharge property generated in contact opening was measured. In the measurement of an arc discharge property, an arc current waveform and an arc voltage waveform in contact opening was measured with an oscilloscope (WAVE SURFER 454VL, manufactured by Teledyne LeCroy, Inc.). Then, an arc power waveform was created based on a product of the arc current waveform and the arc voltage waveform, a time when arc discharge continued was defined as arc duration (msec), and an integrated value of the arc power waveform in the arc duration was calculated as arc energy (J). The arc discharge property was evaluated based on the length of the arc duration and the magnitude of the arc energy. In this evaluation of an arc discharge property, an average obtained with the number of measurements n=1 to 15 was defined as a property value.

[0116] [Measurement of Contact Resistance and Heat Generation in DC High-Voltage Relay]

[0117] Furthermore, the contacts respectively formed of the contact materials of the examples and comparative examples were measured for contact resistance. As the contact resistance, each of the contact materials was incorporated in a relay similar to that used in the evaluation test for an arc discharge property described above, and a value obtained in a state after performing a switching operation once under the same conditions was measured. The measurement of the contact resistance was performed after the switching operation with the DC high-voltage relay connected to a resistance measuring circuit (DC 5 V, 30 A) prepared separately from an interruption circuit. In the measurement of contact resistance with the resistance measuring circuit, a voltage drop between the terminals was measured at the time when a current (30 A) was continuously fed to the circuit for 30 minutes. A value obtained by dividing the measured voltage drop value (mV) by the fed current (30 A) was defined as the contact resistance (mΩ).

[0118] In addition, a temperature rise caused by heat generation at the contact was measured in contact resistance measurement. The heat generation was measured in terms of a temperature rise at a terminal portion for connecting the relay containing the contact material to the resistance measuring circuit. In this measurement, the temperatures of two terminals used as an anode-side terminal and a cathode-side terminal were measured at the time of elapse of 30 minutes after the start of continuous feeding of a current for the contact resistance measurement described above, an average of temperature differences between the measured temperature and room temperature was defined as a temperature rise (° C.). The measurement and evaluation of the contact resistance in the DC high-voltage relay were performed with the number of measurements n=1.

[0119] Tables 3 and 4 show evaluation results of the interruption durability, the arc discharge property, and the contact resistance/heat generation measurement in the DC high-voltage relays of the present embodiment.

TABLE-US-00003 TABLE 3 Evaluation in DC high-voltage relay Content Interrup- of metal Con- Open- tion dura- Contact Heat M tact ing bility Arc Arc resis- genera- Composition (mass %)*.sup.1 (mass force force evalua- duration energy tance tion Ag Zn Sn In Ni Te Bi Cu Mg %) (gf) (gf) tion (msec.) (J) (mΩ) (° C.) Ex. 1 Balance 0.20 — — — — — — — 0.20 75 125 ∘ 4.24 75.63 1.10 19.13 Ex. 2 1.00 — — — — — — — 1.00 ∘ 4.48 75.16 1.37 20.80 Ex. 3 2.50 — — — — — — — 2.50 ∘ 5.12 77.47 2.22 20.72 Ex. 4 5.00 — — — — — — — 5.00 ∘ 5.59 84.47 2.40 28.15 Ex. 5 6.00 — — — — — — — 6.00 ∘ 5.81 88.28 2.35 27.89 Ex. 6 6.50 — — — — — — — 6.50 ∘ 5.59 89.59 2.28 27.30 Ex. 7 8.00 — — — — — — — 8.00 ∘ 5.97 93.00 2.41 27.29 Ex. 8 0.60 0.40 — — — — — — 1.00 ∘ 5.19 78.61 1.99 25.83 Ex. 9 2.40 1.60 — — — — — — 4.00 ∘ 5.51 78.22 2.49 28.65 Ex. 10 4.80 3.20 — — — — — — 8.00 ∘ 5.79 86.78 2.41 27.82 Ex. 11 0.20 — — — — — — — 0.20 ∘ 4.65 75.05 0.97 19.51 Ex. 12 3.00 — — — — — — — 3.00 ∘ 5.49 82.03 1.23 21.62 Ex. 13 0.33 0.67 — — — — — — 1.00 ∘ 5.24 85.26 2.38 28.45 Ex. 14 1.50 0.50 — — — — — — 2.00 ∘ 5.14 82.97 1.51 22.36 Ex. 15 1.00 1.00 — — — — — — 2.00 ∘ 5.15 86.57 2.53 29.48 Ex. 16 0.30 1.70 — — — — — — 2.00 ∘ 5.68 86.10 1.77 24.67 Ex. 17 3.90 0.10 — — — — — — 4.00 ∘ 5.25 85.74 2.07 27.24 Ex. 18 3.00 1.00 — — — — — — 4.00 ∘ 5.50 87.87 1.92 25.31 Ex. 19 2.00 2.00 — — — — — — 4.00 ∘ 5.43 85.05 2.05 27.54 Ex. 20 1.40 2.60 — — — — — — 4.00 ∘ 5.57 94.14 2.42 28.59 Ex. 21 0.60 3.40 — — — — — — 4.00 ∘ 5.64 93.37 2.12 27.18 Ex. 22 6.00 2.00 — — — — — — 8.00 ∘ 5.65 89.03 2.66 29.76 Ex. 23 4.00 4.00 — — — — — — 8.00 ∘ 5.67 94.47 1.79 24.44 Ex. 24 2.70 5.30 — — — — — — 8.00 ∘ 5.92 93.09 2.36 28.85 Ex. 25 1.00 7.00 — — — — — — 8.00 ∘ 5.81 99.54 2.44 29.46 Ex. 26 0.30 7.70 — — — — — — 8.00 ∘ 5.62 96.74 2.18 27.37 Ex. 27 0.50 — 0.10 — — — — — 0.60 ∘ 4.49 75.68 1.48 23.85 Ex. 28 1.50 — 0.50 — — — — — 2.00 ∘ 5.38 86.56 2.13 27.39 Ex. 29 1.00 — 1.00 — — — — — 2.00 ∘ 5.34 86.90 1.71 23.73 Ex. 30 3.90 — 0.10 — — — — — 4.00 ∘ 5.15 86.33 1.34 21.84 Ex. 31 3.00 — 1.00 — — — — — 4.00 ∘ 5.47 89.35 1.35 21.35 Ex. 32 2.00 — 2.00 — — — — — 4.00 ∘ 4.92 84.75 1.98 27.48 Ex. 33 6.00 — 2.00 — — — — — 8.00 ∘ 5.56 90.55 1.33 21.49 Ex. 34 4.00 — 4.00 — — — — — 8.00 ∘ 5.36 94.46 2.39 28.76 Ex. 35 4.00 — 4.00 — — — — — 8.00 ∘ 5.57 84.07 1.54 22.36 Ex. 36 2.00 — 6.00 — — — — — 8.00 ∘ 5.52 88.62 0.94 19.06 Ex. 37 0.50 — — 0.50 — — — — 1.00 ∘ 5.36 85.48 2.30 28.24 Ex. 38 7.90 — — 0.10 — — — — 8.00 ∘ 5.40 83.33 1.47 22.26 Ex. 39 6.80 — — 1.20 — — — — 8.00 ∘ 5.52 81.71 1.55 23.94 Ex. 40 0.50 — — — 0.50 — — — 1.00 ∘ 5.32 88.45 2.48 29.67 Ex. 41 4.50 — — — 1.50 — — — 6.00 ∘ 5.73 91.55 2.46 29.68 Ex. 42 7.90 — — — 0.10 — — — 8.00 ∘ 5.95 97.62 1.91 26.23 Ex. 43 0.50 — — — — 0.50 — — 1.00 ∘ 5.26 89.76 2.23 27.95 Ex. 44 7.90 — — — — 0.10 — — 8.00 ∘ 5.26 93.26 1.78 25.48 Ex. 45 5.70 0.10 0.10 0.10 — — — — 6.00 ∘ 5.37 83.26 1.65 25.29 Ex. 46 5.60 0.10 0.10 0.10 0.10 — — — 6.00 ∘ 5.48 97.27 1.61 24.32 Ex. 47 5.80 0.10 — — — 0.10 — — 6.00 ∘ 5.59 91.61 2.14 27.62 Ex. 48 3.40 — — — — — 3.40 — 6.80 ∘ 5.26 83.21 1.87 25.79 Ex. 49 6.00 — — — — — — — 6.00 ∘ 5.32 83.28 1.99 27.96 *.sup.1Concentration based on all metal components.

TABLE-US-00004 TABLE 4 Evaluation in DC high-voltage relay Content Interrup- of metal Con- Open- tion dura- Contact Heat M tact ing bility Arc Arc resis- genera- Composition (mass %)*.sup.1 (mass force force evalua- duration energy tance tion Ag Zn Sn In Ni Te Bi Cl Mg %) (gf) (gf) tion (msec.) (J) (mΩ) (° C.) Comp. Balance — 3.60 1.30 0.10 — — — — 5.00 75 125 ∘ 6.18 100.17 3.03 31.27 Ex. 1 Comp. — 3.30 1.30 0.10 0.30 — — — 5.00 ∘ 6.05 100.08 3.20 32.86 Ex. 2 Comp. — 5.90 1.90 0.20 — — — — 8.00 ∘ 6.94 102.68 5.97 49.52 Ex. 3 Comp. — 6.40 2.50 0.10 1.00 — — — 10.00 ∘ 7.04 107.78 7.56 59.92 Ex. 4 Comp. 10.80  — — — — — — — 10.80 ∘ 6.60 103.12 4.45 43.44 Ex. 5 Comp. 0.10 — — — — — — — 0.10 x 4.18 78.36 1.11 19.61 Ex. 6 Comp. 0.10 — — — — — — — 0.10 x 4.24 79.93 1.34 21.57 Ex. 7 Comp. 11.00  — — — — — — — 11.00 ∘ 6.25 105.23 7.91 64.68 Ex. 8 Comp. 0.30 9.00 — — — — — — 9.30 ∘ 6.76 103.59 3.13 34.98 Ex. 9 Comp. 0.50 — — — 1.50 — — — 2.00 x 5.53 91.14 1.68 25.26 Ex. 10 Comp. 3.50 — — — 2.50 — — — 6.00 x 5.23 96.73 5.04 45.45 Ex. 11 Comp. 0.50 — — — — 1.50 — — 2.00 x 5.35 90.35 1.89 26.75 Ex. 12 Comp. 4.50 — — — — 1.50 — — 6.00 x 5.82 94.45 2.29 28.93 Ex. 13 Comp. 3.50 — — — — 2.50 — — 6.00 x 5.83 97.84 2.34 29.60 Ex. 14 Comp. — 0.20 — — — — — — 0.20 ∘ 6.25 101.43 1.54 24.23 Ex. 15 Comp. — 1.00 — — — — — — 1.00 ∘ 6.34 100.85 2.47 29.43 Ex. 16 Comp. — 3.00 — — — — — — 3.00 ∘ 6.37 104.18 3.16 34.44 Ex. 17 Comp. — 6.00 — — — — — — 6.00 ∘ 6.39 102.06 3.21 35.99 Ex. 18 Comp. — 5.00 1.00 — — — — — 6.00 ∘ 6.75 110.68 3.13 33.80 Ex. 19 Comp. — 5.90 — — — 0.10 — — 6.00 ∘ 6.87 109.23 3.73 37.08 Ex. 20 Comp. — 8.00 — — — — — — 8.00 ∘ 6.45 105.84 4.56 43.03 Ex. 21 Comp. 6.00 — — — — — — — 6.00 x 5.56 82.09 3.01 34.89 Ex. 22 Comp. 100 — — — — — — — — 0.00 x 4.09 77.94 0.96 17.57 Ex. 23 *.sup.1Concentration based on all metal components.

[0120] From the evaluation results shown in Table 4, it was first confirmed that pure Ag is inadequate as a contact material for a DC high-voltage relay. In the DC high-voltage relay in which pure Ag was applied to the contacts (Comparative Example 23), welding occurred when the number of interruptions was less than 10. The relay interruption test was performed in the present embodiment under comparatively severe conditions, but it is not preferable that welding occurs when a switching operation is performed less than 10 times.

[0121] On the other hand, it is deemed that the DC high-voltage relays respectively using the contact materials essentially containing Zn as metal M (Examples 1 to 49) have interruption durability. In these examples, it is understood that the arc duration is shortened, the arc energy is reduced, and hence the arc discharge property is excellent.

[0122] In this embodiment, DC high-voltage relays respectively using, as a general contact material for a relay, the contact material in which Zn was not contained and the content of metal M including Sn, In and the like was about 10% by mass (Comparative Example 4), and the contact materials in which Zn was not contained and the content of Sn, In and the like was comparatively small (Comparative Examples 1 to 3, and 15 to 21) were also evaluated, and it was confirmed that all of these were inferior in the arc discharge property to the examples. This result is deemed to indicate that an arc discharge property is improved by using Zn as an essential constituent element of the contact material. When the content of Zn is more than 8% by mass, however, an arc discharge property is equivalent to that of the conventional contact material (Comparative Examples 5 and 8). Therefore, the upper limit of the content of metal M including Zn needs to be about 8% by mass. Regarding the average particle size of oxide particles in the contact material, since Comparative Examples 10 to 14 were poor in the interruption durability, it is understood that the average particle size of oxide particles needs to be 0.4 μm or less.

[0123] Besides, regarding the problems of contact resistance and heat generation, the results of measurement performed with the contact materials actually incorporated in the relays show superiority of the contact materials of Examples 1 to 49. The contact materials of examples have a lower temperature rise value as compared to those of comparative examples. The amount of heat generation at contacts is proportional to a square of current and a contact resistance value. In the measurement test in this embodiment, a relatively low current of 30 A is fed, but when the fed current increases with the contact material applied to an actual DC high-voltage relay, the temperature rise further increases.

[0124] Metal M of the contact material applied in the present invention essentially contains Zn, and may also contain metals other than Zn (Sn). Through comparison with the comparative examples, an arc discharge property and contact resistance are excellent even when another metal is added in addition to Zn (Examples 8 to 10, and 13 to 48). In a Ag oxide-based contact material, a Sn oxide (SnO.sub.2) and the like has an action of improving welding resistance. Therefore, when a Ag oxide-based contact material containing Sn in addition to Zn is used, both an arc discharge property and welding resistance can be adjusted. Another metal to be added in addition to Zn does not have an advantageous action on an arc discharge property, and hence the addition is not essential.

[0125] Second Embodiment: In this embodiment, DC high-voltage relays similar to those of the first embodiment in which a magnetic force of an arc-extinguishing magnet was set to be low were manufactured, and arc discharge properties obtained when contact materials of examples and comparative examples were respectively incorporated therein were evaluated.

[0126] In this embodiment, DC high-voltage relays having a double-break structure similarly to those of the first embodiment were prepared, and rivet-type contacts formed of the contact materials were bonded to movable terminals and fixed terminals of the relays. The size of the contacts was the same as that of the first embodiment. One neodymium magnet having a magnetic flux density of 200 mT was disposed as an arc-extinguishing magnet on the periphery of the movable contact and the fixed contact, and thus, the usage of neodymium, that is, a rare earth element, was reduced as compared with that in the first embodiment. A magnetic flux density at the central position in contacting of the contacts was 13 mT as measured with a gaussmeter.

[0127] An evaluation test for an arc discharge property of the DC high-voltage relays performed in the present embodiment is the same as that performed in the first embodiment, and a switching operation of the contacts was performed under conditions: voltage/current: DC 360 V/400 A, and the contact force/opening force of movable contact: 75 gf/125 gf, and an arc discharge property obtained in each operation was evaluated. Then, the arc discharge property was measured as an index in the same manner as in the first embodiment. In this evaluation of an arc discharge property, an average obtained with the number of measurements n=1 to 15 was adopted. Tables 5 and 6 show measurement results.

TABLE-US-00005 TABLE 5 Content High-voltage evaluation (13 mT) of metal Contact Opening Interruption Arc Arc Composition (mass %)*.sup.1 M force force durability duration energy Ag Zn Sn In Ni Te Bi Cu Mg (mass %) (gf) (gf) evaluation (msec.) (J) Ex. 1 Balance 0.20 — — — — — — — 0.20 75 125 ∘ 6.00 100.67 Ex. 2 1.00 — — — — — — — 1.00 ∘ 6.41 101.43 Ex. 3 2.50 — — — — — — — 2.50 ∘ 6.84 103.01 Ex. 4 5.00 — — — — — — — 5.00 ∘ 6.71 101.13 Ex. 5 6.00 — — — — — — — 6.00 ∘ 7.06 105.79 Ex. 6 6.50 — — — — — — — 6.50 ∘ 7.03 107.09 Ex. 7 8.00 — — — — — — — 8.00 ∘ 7.46 109.56 Ex. 8 0.60 0.40 — — — — — — 1.00 ∘ 6.45 105.42 Ex. 9 2.40 1.60 — — — — — — 4.00 ∘ 7.57 103.92 Ex. 10 4.80 3.20 — — — — — — 8.00 ∘ 7.81 108.10 Ex. 11 0.20 — — — — — — — 0.20 ∘ 5.98 102.88 Ex. 12 3.00 — — — — — — — 3.00 ∘ 6.28 104.07 Ex. 13 0.33 0.67 — — — — — — 1.00 ∘ 6.66 108.88 Ex. 14 1.50 0.50 — — — — — — 2.00 ∘ 6.46 101.78 Ex. 15 1.00 1.00 — — — — — — 2.00 ∘ 6.46 104.07 Ex. 16 0.30 1.70 — — — — — — 2.00 ∘ 6.85 104.83 Ex. 17 3.90 0.10 — — — — — — 4.00 ∘ 6.83 102.45 Ex. 18 3.00 1.00 — — — — — — 4.00 ∘ 6.84 102.26 Ex. 19 2.00 2.00 — — — — — — 4.00 ∘ 6.98 104.17 Ex. 20 1.40 2.60 — — — — — — 4.00 ∘ 6.78 104.32 Ex. 21 0.60 3.40 — — — — — — 4.00 ∘ 7.16 108.27 Ex. 22 6.00 2.00 — — — — — — 8.00 ∘ 7.44 107.89 Ex. 23 4.00 4.00 — — — — — — 8.00 ∘ 6.68 108.01 Ex. 24 2.70 5.30 — — — — — — 8.00 ∘ 7.80 109.03 Ex. 25 1.00 7.00 — — — — — — 8.00 ∘ 7.57 111.16 Ex. 26 0.30 7.70 — — — — — — 8.00 ∘ 7.19 107.24 Ex. 27 0.50 — 0.10 — — — — — 0.60 ∘ 6.33 102.47 Ex. 28 1.50 — 0.50 — — — — — 2.00 ∘ 6.58 103.38 Ex. 29 1.00 — 1.00 — — — — — 2.00 ∘ 6.76 104.74 Ex. 30 3.90 — 0.10 — — — — — 4.00 ∘ 6.57 102.67 Ex. 31 3.00 — 1.00 — — — — — 4.00 ∘ 6.76 103.34 Ex. 32 2.00 — 2.00 — — — — — 4.00 ∘ 6.73 104.45 Ex. 33 6.00 — 2.00 — — — — — 8.00 ∘ 7.46 106.85 Ex. 34 4.00 — 4.00 — — — — — 8.00 ∘ 7.48 107.60 Ex. 35 4.00 — 4.00 — — — — — 8.00 ∘ 7.08 103.84 Ex. 36 2.00 — 6.00 — — — — — 8.00 ∘ 6.73 106.74 Ex. 37 0.50 — — 0.50 — — — — 1.00 ∘ 6.50 108.33 Ex. 38 7.90 — — 0.10 — — — — 8.00 ∘ 7.08 109.68 Ex. 39 6.80 — — 1.20 — — — — 8.00 ∘ 7.02 103.86 Ex. 40 0.50 — — — 0.50 — — — 1.00 ∘ 6.76 109.92 Ex. 41 4.50 — — — 1.50 — — — 6.00 ∘ 7.08 104.81 Ex. 42 7.90 — — — 0.10 — — — 8.00 ∘ 7.05 104.94 Ex. 43 0.50 — — — — 0.50 — — 1.00 ∘ 6.72 110.67 Ex. 44 7.90 — — — — 0.10 — — 8.00 ∘ 7.17 108.10 Ex. 45 5.70 0.10 0.10 0.10 — — — — 6.00 ∘ 6.28 103.15 Ex. 46 5.60 0.10 0.10 0.10 0.10 — — — 6.00 ∘ 6.52 108.14 Ex. 47 5.80 0.10 — — — 0.10 — — 6.00 ∘ 6.46 107.14 Ex. 48 3.40 — — — — — 3.40 — 6.80 ∘ 6.79 107.58 Ex. 49 6.00 — — — — — — — 6.00 ∘ 7.31 103.03 *.sup.1Concentration based on all metal components.

TABLE-US-00006 TABLE 6 Content High-voltage evaluation (13 mT) of metal Contact Opening Interruption Arc Arc Composition (mass %)*.sup.1 M force force durability duration energy Ag Zn Sn In Ni Te Bi Cu Mg (mass %) (gf) (gf) evaluation (msec.) (J) Comp. Balance — 3.60 1.30 0.10 — — — — 5.00 75 125 ∘ 8.30 117.14 Ex. 1 Comp. — 3.30 1.30 0.10 0.30 — — — 5.00 ∘ 8.07 115.34 Ex. 2 Comp. — 5.90 1.90 0.20 — — — — 8.00 ∘ 8.86 125.05 Ex. 3 Comp. — 6.40 2.50 0.10 1.00 — — — 10.00 ∘ 9.10 134.10 Ex. 4 Comp. 10.80  — — — — — — — 10.80 ∘ 8.08 115.72 Ex. 5 Comp. 0.10 — — — — — — — 0.10 x 5.88 99.84 Ex. 6 Comp. 0.10 — — — — — — — 0.10 x 5.80 99.15 Ex. 7 Comp. 11.00  — — — — — — — 11.00 ∘ 8.35 132.78 Ex. 8 Comp. 0.30 9.00 — — — — — — 9.30 ∘ 8.25 135.46 Ex. 9 Comp. — 0.20 — — — — — — 0.20 ∘ 8.63 118.92 Ex. 15 Comp. — 1.00 — — — — — — 1.00 ∘ 8.05 118.03 Ex. 16 Comp. — 3.00 — — — — — — 3.00 ∘ 8.24 116.34 Ex. 17 Comp. — 6.00 — — — — — — 6.00 ∘ 8.58 116.71 Ex. 18 Comp. — 5.00 1.00 — — — — — 6.00 ∘ 8.67 114.61 Ex. 19 Comp. — 5.90 — — — 0.10 — — 6.00 ∘ 8.18 117.61 Ex. 20 Comp. — 8.00 — — — — — — 8.00 ∘ 8.07 125.38 Ex. 21 Comp. 100 — — — — — — — — 0.00 x 5.32 79.80 Ex. 23 *.sup.1Concentration based on all metal components.

[0128] In the DC high-voltage relays of the present embodiment, the magnetic force of an arc-extinguishing magnet was set to be a half of that of the first embodiment. The magnetic force reduction due to the reduction of the rare earth element increases arc duration and arc energy. Also under such circumstances, the arc duration and the arc energy of the contact material of each example containing Zn are suppressed. The result of this embodiment is deemed to support that the usage of a rare earth element is reduced by reducing the magnetic force of an arc-extinguishing magnet of a DC high-voltage relay.

[0129] Third Embodiment: In the first and second embodiments, DC high-voltage relays of double-break structure containing various contact materials (FIG. 1) were manufactured, and interruption durability tests were conducted in which interruption operations at the time of abnormality were simulated. In this embodiment, the DC high-voltage relay was mounted as a system main relay for a hybrid vehicle or the like, and switching operations in normal use were simulated to evaluate durability and contact resistance. The normal use refers to use conditions under loads from power source on/off operations in normal circuits.

[0130] Normal use conditions of the DC high-voltage relay which are intended by the present invention will be described in detail. In DC circuits for hybrid vehicles and the like, a precharge relay appropriate to an inrush current is installed for preventing damage of contacts of a system main relay by a high inrush current at the time when a power source is turned on. After the precharge relay absorbs the high inrush current, the power source of the system main relay is turned on.

[0131] In this embodiment, a capacitor load durability test was conducted in which a DC high-voltage relay having the same structure as that of the first embodiment in which the contact material of each example was incorporated was incorporated in a test circuit as shown in FIG. 3, and switching operations of contacts with an inrush current reduced in the manner described above were simulated for evaluating durability. The test conditions for the capacitor load durability test in this embodiment were set as follows: voltage: DC 20 V, load current: 80 A (at the time of inrush)/1 A (at the time of interruption) and switching cycle: 1 second (on)/9 seconds (off). The contact force/opening force of the movable contact was set to 75 gf/125 gf. In this capacitor load durability test, the number of operations of 10,000 times was set as an acceptance criterion for durability life, and a relay in which the contacts were not welded within the number of operations of 10,000 times was evaluated as acceptable (o), and a relay in which defective operation such as welding at the contacts occurred within the number of operations of 10,000 times was evaluated as unacceptable (x).

[0132] In addition, in this embodiment, the contact resistance and the temperature rise (heat generation amount) were measured as in the first embodiment. After the capacitor load durability test, the contact resistance was measured with a change made to connection of the relay to a resistance measuring circuit (DC5V30A) which is different from a capacitor load durability test circuit. The measurement method was the same as in the first embodiment. In addition, a temperature rise caused by heat generation at the contact was measured in the contact resistance measurement.

[0133] In the measurement and evaluation in the capacitor load durability test performed in this embodiment, an average obtained with the number of measurements n=1 to 3 was adopted. Table 7 shows durability evaluation results and measurement results of contact resistance and temperature rise obtained in the present embodiment.

TABLE-US-00007 TABLE 7 Content Capacitor load durability test of metal Contact Opening Interruption Contact Heat Composition (mass %)*.sup.1 M force force durability resistance generation Ag Zn Sn In Ni Te Bi Cu Mg (mass %) (gf) (gf) evaluation (mΩ) (° C.) Ex. 1 Balance 0.20 — — — — — — — 0.20 75 125 ∘ 0.90 17.58 Ex. 2 1.00 — — — — — — — 1.00 ∘ 0.86 17.24 Ex. 3 2.50 — — — — — — — 2.50 ∘ 1.19 20.40 Ex. 4 5.00 — — — — — — — 5.00 ∘ 1.45 21.37 Ex. 5 6.00 — — — — — — — 6.00 ∘ 1.05 18.93 Ex. 6 6.50 — — — — — — — 6.50 ∘ 1.22 19.65 Ex. 7 8.00 — — — — — — — 8.00 ∘ 1.39 19.81 Ex. 8 0.60 0.40 — — — — — — 1.00 ∘ 1.09 19.49 Ex. 9 2.40 1.60 — — — — — — 4.00 ∘ 1.67 23.93 Ex. 10 4.80 3.20 — — — — — — 8.00 ∘ 1.87 24.09 Ex. 11 0.20 — — — — — — — 0.20 ∘ 1.15 20.69 Ex. 12 3.00 — — — — — — — 3.00 ∘ 1.50 24.01 Ex. 13 0.33 0.67 — — — — — — 1.00 ∘ 1.08 19.25 Ex. 14 1.50 0.50 — — — — — — 2.00 ∘ 1.23 20.43 Ex. 15 1.00 1.00 — — — — — — 2.00 ∘ 1.17 20.28 Ex. 16 0.30 1.70 — — — — — — 2.00 ∘ 1.31 21.93 Ex. 17 3.90 0.10 — — — — — — 4.00 ∘ 1.58 23.52 Ex. 18 3.00 1.00 — — — — — — 4.00 ∘ 1.40 21.26 Ex. 19 2.00 2.00 — — — — — — 4.00 ∘ 1.67 23.64 Ex. 20 1.40 2.60 — — — — — — 4.00 ∘ 1.48 22.00 Ex. 21 0.60 3.40 — — — — — — 4.00 ∘ 1.49 22.48 Ex. 22 6.00 2.00 — — — — — — 8.00 ∘ 1.31 21.70 Ex. 23 4.00 4.00 — — — — — — 8.00 ∘ 1.41 21.47 Ex. 24 2.70 5.30 — — — — — — 8.00 ∘ 1.25 22.05 Ex. 25 1.00 7.00 — — — — — — 8.00 ∘ 1.99 26.98 Ex. 26 0.30 7.70 — — — — — — 8.00 ∘ 1.74 24.89 Ex. 27 0.50 — 0.10 — — — — — 0.60 ∘ 1.24 22.48 Ex. 28 1.50 — 0.50 — — — — — 2.00 ∘ 1.55 22.92 Ex. 29 1.00 — 1.00 — — — — — 2.00 ∘ 1.34 21.06 Ex. 30 3.90 — 0.10 — — — — — 4.00 ∘ 1.45 23.48 Ex. 31 3.00 — 1.00 — — — — — 4.00 ∘ 1.24 21.46 Ex. 32 2.00 — 2.00 — — — — — 4.00 ∘ 1.77 23.70 Ex. 33 6.00 — 2.00 — — — — — 8.00 ∘ 1.85 26.05 Ex. 34 4.00 — 4.00 — — — — — 8.00 ∘ 1.64 21.36 Ex. 35 4.00 — 4.00 — — — — — 8.00 ∘ 1.69 23.54 Ex. 36 2.00 — 6.00 — — — — — 8.00 ∘ 1.65 23.54 Ex. 37 0.50 — — 0.50 — — — — 1.00 ∘ 1.02 18.78 Ex. 38 7.90 — — 0.10 — — — — 8.00 ∘ 1.59 23.74 Ex. 39 6.80 — — 1.20 — — — — 8.00 ∘ 1.27 22.45 Ex. 40 0.50 — — — 0.50 — — — 1.00 ∘ 1.47 22.22 Ex. 41 4.50 — — — 1.50 — — — 6.00 ∘ 1.63 23.94 Ex. 42 7.90 — — — 0.10 — — — 8.00 ∘ 1.92 26.53 Ex. 43 0.50 — — — — 0.50 — — 1.00 ∘ 1.69 23.29 Ex. 44 7.90 — — — — 0.10 — — 8.00 ∘ 1.20 21.60 Ex. 45 5.70 0.10 0.10 0.10 — — — — 6.00 ∘ 1.55 24.48 Ex. 46 5.60 0.10 0.10 0.10 0.10 — — — 6.00 ∘ 1.39 22.99 Ex. 47 5.80 0.10 — — — 0.10 — — 6.00 ∘ 1.32 22.58 Ex. 48 3.40 — — — — — 3.40 — 6.80 ∘ 1.42 22.93 Ex. 49 6.00 — — — — — — — 6.00 ∘ 1.10 21.67 *.sup.1Concentration based on all metal components.

[0134] Table 7 reveals that the DC high-voltage relays of the examples were acceptable for the durability test in the load during normal use (number of operations: 10,000 times). In addition, both contact resistance and heat generation had low values in the same manner as in the examples of the other embodiments. From the evaluation results of the present embodiment, it was confirmed that the DC high-voltage relays of the examples in which the contact materials containing Zn as an essential metal and reduced in the amount of oxides are applied can usefully function even in consideration of actual use conditions in a hybrid vehicle and the like.

[0135] From the results of the above first to third embodiments, it was confirmed that the DC high-voltage relay of the present invention operates suitably as a DC high-voltage relay due to optimization of the configurations of the contact materials of the movable contact and the fixed contact. The DC high-voltage relay of the present invention can effectively operate with respect to interruption upon abnormal operations of the circuit, and stably operate in normal use.

[0136] Fourth Embodiment: In this embodiment, DC high-voltage relays in which a magnetic force of an arc-extinguishing magnet was set to be intermediate between that of the first embodiment (26 mT) and that of the second embodiment (13 mT) were manufactured, and arc discharge properties obtained when contact materials of examples and comparative examples were respectively incorporated therein were evaluated. DC high-voltage relays having a double-break structure similarly to those of the first embodiment were prepared, and one neodymium magnet having a magnetic flux density of 200 mT and one ferrite magnet having a magnetic flux density of 54 mT were disposed as arc-extinguishing magnets on the periphery of the movable contact and the fixed contact. Thus, the usage of a rare earth element was reduced by using a ferrite magnet not containing neodymium, that is, a rare earth element, with the same number of magnets used as in the first embodiment. A magnetic flux density at the central position in contacting of the contacts was 18 mT as measured with a gaussmeter.

[0137] Then, in the same manner as in the first and second embodiments, a switching operation of the contacts was performed under conditions: voltage/current: DC 360 V/400 A, and the contact force/opening force of movable contact: 75 gf/125 gf, and an arc discharge property obtained in each operation was evaluated. An average obtained with the number of measurements n=1 to 15 was adopted. Table 8 shows measurement results. In this embodiment, the contact materials of Examples 1, 2, 5, 7, 12, 25, 35, 38, 42, 44 to 46, and 48 and Comparative Examples 2, 3, 5, 9, 15 to 18, 20, 21 and 23 were used.

TABLE-US-00008 TABLE 8 Content Evaluation in DC high-voltage relay(18 mT) of metal Contact Opening Interruption Arc Arc Composition (mass %)*.sup.1 M force force durability duration energy Ag Zn Sn In Ni Te Bi Cu Mg (mass %) (gf) (gf) evaluation (msec.) (J) Ex. 1 Balance 0.20 — — — — — — — 0.20 75 125 ∘ 4.79 90.98 Ex. 2 1.00 — — — — — — — 1.00 ∘ 5.08 92.20 Ex. 5 6.00 — — — — — — — 6.00 ∘ 5.93 100.70 Ex. 7 8.00 — — — — — — — 8.00 ∘ 6.13 101.48 Ex. 12 3.00 — — — — — — — 3.00 ∘ 5.78 94.13 Ex. 25 1.00 7.00 — — — — — — 8.00 ∘ 5.71 97.95 Ex. 35 4.00 — 4.00 — — — — — 8.00 ∘ 5.51 93.09 Ex. 38 7.90 — — 0.10 — — — — 8.00 ∘ 5.96 95.20 Ex. 42 7.90 — — — 0.10 — — — 8.00 ∘ 5.52 89.73 Ex. 44 7.90 — — — — 0.10 — — 8.00 ∘ 5.81 92.55 Ex. 45 5.70 0.10 0.10 0.10 — — — — 6.00 ∘ 5.48 92.14 Ex. 46 5.60 0.10 0.10 0.10 0.10 — — — 6.00 ∘ 5.92 97.12 Ex. 48 3.40 — — — — — 3.40 — 6.80 ∘ 5.67 90.80 Comp. — 3.30 1.30 0.10 0.30 — — — 5.00 ∘ 6.31 104.25 Ex. 2 Comp. — 5.90 1.90 0.20 — — — — 8.00 ∘ 6.97 108.14 Ex. 3 Comp. 10.80  — — — — — — — 10.80 ∘ 6.60 104.96 Ex. 5 Comp. 0.30 9.00 — — — — — — 9.30 ∘ 6.38 106.04 Ex. 9 Comp. — 0.20 — — — — — — 0.20 ∘ 6.25 104.43 Ex. 15 Comp. — 1.00 — — — — — — 1.00 ∘ 6.34 106.54 Ex. 16 Comp. — 3.00 — — — — — — 3.00 ∘ 6.32 104.89 Ex. 17 Comp. — 6.00 — — — — — — 6.00 ∘ 6.28 104.48 Ex. 18 Comp. — 5.90 — — — 0.10 — — 6.00 ∘ 6.27 104.48 Ex. 20 Comp. — 8.00 — — — — — — 8.00 ∘ 6.68 106.82 Ex. 21 Comp. 100 — — — — — — — — 0.00 x 4.14 79.77 Ex. 23 *.sup.1Concentration based on all metal components.

[0138] Table 8 reveals that arc duration and arc energy are suppressed in the DC high-voltage relays using the contact materials of the examples containing Zn. In this respect, this embodiment is the same as the second embodiment. According to the present embodiment, applicability of a magnet different from a rare earth magnet (neodymium magnet) to an arc-extinguishing magnet mounted on a DC high-voltage relay can be confirmed. Also the contents of this embodiment are deemed to support the reduction of the usage of a rare earth element.

[0139] Fifth Embodiment: In this embodiment, DC high-voltage relays in which the contact force was increased with the opening force reduced as compared with those of the DC high-voltage relays of the first to fourth embodiments were manufactured. In this embodiment, arc discharge properties of DC high-voltage relays having a double-break structure and having the contact force/opening force of 100 gf/90 gf were evaluated. The other evaluation conditions were the same as those of the first embodiment. In this embodiment, the contact materials of Examples 1, 2, 5, 7, 12, 25, 35, 38, 42, 44 to 46 and 48 and Comparative examples 2, 3, 5, 9, 15 to 18, 20 and 21 were used.

[0140] Besides, in this embodiment, a DC high-voltage relay in which both the contact force and the opening force were less than 100 gf was also evaluated as a reference example. The contact materials of Examples 1 and 2 were used to manufacture DC high-voltage relays having a double-break structure in which the strength of a contact pressure spring and a restoration spring was lower than that of the first to fourth embodiment (Reference Examples 1 and 2). Then, a switching operation of the contacts was similarly performed to evaluate an arc discharge property in each operation. Table 9 shows results.

TABLE-US-00009 TABLE 9 Content Evaluation in DC high-voltage relay of metal Contact Opening Interruption Arc Arc Composition (mass %)*.sup.1 M force force durability duration energy Ag Zn Sn In Ni Te Bi Cu Mg (mass %) (gf) (gf) evaluation (msec.) (J) Ex. 1 Balance 0.20 — — — — — — — 0.20 100 90 ∘ 4.35 77.32 Ex. 2 1.00 — — — — — — — 1.00 ∘ 4.35 79.24 Ex. 5 6.00 — — — — — — — 6.00 ∘ 5.91 89.92 Ex. 7 8.00 — — — — — — — 8.00 ∘ 6.10 96.18 Ex. 12 3.00 — — — — — — — 3.00 ∘ 5.39 89.22 Ex. 25 1.00 7.00 — — — — — — 8.00 ∘ 5.53 92.68 Ex. 35 4.00 — 4.00 — — — — — 8.00 ∘ 5.71 86.76 Ex. 38 7.90 — — 0.10 — — — — 8.00 ∘ 5.78 87.13 Ex. 42 7.90 — — — 0.10 — — — 8.00 ∘ 5.74 88.16 Ex. 44 7.90 — — — — 0.10 — — 8.00 ∘ 5.92 90.12 Ex. 45 5.70 0.10 0.10 0.10 — — — — 6.00 ∘ 5.31 88.86 Ex. 46 5.60 0.10 0.10 0.10 0.10 — — — 6.00 ∘ 5.52 89.32 Ex. 48 3.40 — — — — — 3.40 — 6.80 ∘ 5.86 89.12 Comp. — 3.30 1.30 0.10 0.30 — — — 5.00 ∘ 6.85 106.13 Ex. 2 Comp. — 5.90 1.90 0.20 — — — — 8.00 ∘ 6.70 106.19 Ex. 3 Comp. 10.80  — — — — — — — 10.80 ∘ 6.43 101.71 Ex. 5 Comp. 0.30 9.00 — — — — — — 9.30 ∘ 6.65 101.92 Ex. 9 Comp. — 0.20 — — — — — — 0.20 ∘ 6.40 100.97 Ex. 15 Comp. — 1.00 — — — — — — 1.00 ∘ 6.58 101.87 Ex. 16 Comp. — 3.00 — — — — — — 3.00 ∘ 6.72 101.70 Ex. 17 Comp. — 6.00 — — — — — — 6.00 ∘ 6.80 105.54 Ex. 18 Comp. — 5.90 — — — 0.10 — — 6.00 ∘ 6.34 100.32 Ex. 20 Comp. — 8.00 — — — — — — 8.00 ∘ 6.38 101.02 Ex. 21 Reference Balance 0.20 — — — — — — — 0.20 75 50 x 4.57 75.44 Example 1 Reference 1.00 — — — — — — — 1.00 x 4.78 74.06 Example 2 *.sup.1Concentration based on all metal components.

[0141] Table 9 reveals that also regarding a DC high-voltage relay in which the contact force is increased with the opening force reduced as compared with those of the first embodiment and the like, DC high-voltage relays using the contact materials of the examples are good in interruption durability, and arc duration and arc energy are suppressed. Referring to the results of Reference Examples 1 and 2, when the contact force and the opening force of a DC high-voltage relay are less than 100 gf, the interruption durability is inferior even when the contact materials of Examples 1 and 2 are applied. Although the content of metal M may be a cause, this is probably because the contact force or the opening force was too low (less than 100 gf).

[0142] Sixth Embodiment: In this embodiment, DC high-voltage relays having the same structure as that of the first embodiment in which the voltage/current were set to DC 200 V/200 A were manufactured. Besides, DC high-voltage relays in which the contact force and the opening force were set to be higher than in the first to fifth embodiments were manufactured, and arc discharge properties obtained when the contact materials of the examples and the comparative examples were incorporated therein were evaluated. For adjusting the contact force and the opening force, DC high-voltage relays having a double-break structure similar to that of the first embodiment were prepared, and those having larger strength of contact pressure springs and restoration springs were used. In this embodiment, two DC high-voltage relays, one of which having the contact force/opening force of 250 gf/600 gf and the other having the contact force/opening force of 500 gf/1250 gf, were manufactured, and a switching operation of contacts was performed in each of the relays to evaluate an arc discharge property in each operation. The other evaluation conditions were the same as those of the first embodiment. In this embodiment, the contact materials of Examples 1, 2, 5, 7, 12, 25, 35, 38, 42, 44 to 46 and 48 and Comparative Examples 2, 3, 5, 9, 15 to 18, 20 and 21 were used. Tables 10 and 11 show evaluation results of these.

TABLE-US-00010 TABLE 10 Content Evaluation in DC high-voltage relay of metal Contact Opening Interruption Arc Arc Composition (mass %)*.sup.1 M force force durability duration energy Ag Zn Sn In Ni Te Bi Cu Mg (mass %) (gf) (gf) evaluation (msec.) (J) Ex. 1 Balance 0.20 — — — — — — — 0.20 250 600 ∘ 2.04 19.69 Ex. 2 1.00 — — — — — — — 1.00 ∘ 2.03 19.41 Ex. 5 6.00 — — — — — — — 6.00 ∘ 2.09 19.79 Ex. 7 8.00 — — — — — — — 8.00 ∘ 2.07 19.86 Ex. 12 3.00 — — — — — — — 3.00 ∘ 2.00 19.67 Ex. 25 1.00 7.00 — — — — — — 8.00 ∘ 2.14 19.62 Ex. 35 4.00 — 4.00 — — — — — 8.00 ∘ 2.15 19.75 Ex. 38 7.90 — — 0.10 — — — — 8.00 ∘ 2.12 19.16 Ex. 42 7.90 — — — 0.10 — — — 8.00 ∘ 2.18 19.67 Ex. 44 7.90 — — — — 0.10 — — 8.00 ∘ 2.16 18.53 Ex. 45 5.70 0.10 0.10 0.10 — — — — 6.00 ∘ 2.06 19.54 Ex. 46 5.60 0.10 0.10 0.10 0.10 — — — 6.00 ∘ 2.01 19.85 Ex. 48 3.40 — — — — — 3.40 — 6.80 ∘ 2.12 19.11 Comp. — 3.30 1.30 0.10 0.30 — — — 5.00 ∘ 2.54 20.53 Ex. 2 Comp. — 5.90 1.90 0.20 — — — — 8.00 ∘ 2.38 20.22 Ex. 3 Comp. 10.80 — — — — — — — 10.80 ∘ 2.48 20.81 Ex. 5 Comp. 0.30 9.00 — — — — — — 9.30 ∘ 2.39 21.00 Ex. 9 Comp. — 0.20 — — — — — — 0.20 ∘ 2.31 20.20 Ex. 15 Comp. — 1.00 — — — — — — 1.00 ∘ 2.35 20.23 Ex. 16 Comp. — 3.00 — — — — — — 3.00 ∘ 2.30 20.40 Ex. 17 Comp. — 6.00 — — — — — — 6.00 ∘ 2.45 21.39 Ex. 18 Comp. — 5.90 — — — 0.10 — — 6.00 ∘ 2.33 20.16 Ex. 20 Comp. — 8.00 — — — — — — 8.00 ∘ 2.50 20.31 Ex. 21 *.sup.1Concentration based on all metal components.

TABLE-US-00011 TABLE 11 Content Evaluation in DC high-voltage relay of metal Contact Opening Interruption Arc Arc Composition (mass %)*.sup.1 M force force durability duration energy Ag Zn Sn In Ni Te Bi Cu Mg (mass %) (gf) (gf) evaluation (msec.) (J) Ex. 1 Balance 0.20 — — — — — — — 0.20 500 1250 ∘ 1.94 18.53 Ex. 2 1.00 — — — — — — — 1.00 ∘ 2.01 19.76 Ex. 5 6.00 — — — — — — — 6.00 ∘ 2.08 19.69 Ex. 7 8.00 — — — — — — — 8.00 ∘ 2.09 19.40 Ex. 12 3.00 — — — — — — — 3.00 ∘ 2.08 18.19 Ex. 25 1.00 7.00 — — — — — — 8.00 ∘ 2.11 19.71 Ex. 35 4.00 — 4.00 — — — — — 8.00 ∘ 2.10 20.08 Ex. 38 7.90 — — 0.10 — — — — 8.00 ∘ 2.06 18.89 Ex. 42 7.90 — — — 0.10 — — — 8.00 ∘ 2.18 19.28 Ex. 44 7.90 — — — — 0.10 — — 8.00 ∘ 2.11 18.66 Ex. 45 5.70 0.10 0.10 0.10 — — — — 6.00 ∘ 2.04 19.36 Ex. 46 5.60 0.10 0.10 0.10 0.10 — — — 6.00 ∘ 2.03 18.54 Ex. 48 3.40 — — — — — 3.40 — 6.80 ∘ 2.14 18.22 Comp. — 3.30 1.30 0.10 0.30 — — — 5.00 ∘ 2.40 20.51 Ex. 2 Comp. — 5.90 1.90 0.20 — — — — 8.00 ∘ 2.56 21.08 Ex. 3 Comp. 10.80  — — — — — — — 10.80 ∘ 2.45 20.45 Ex. 5 Comp. 0.30 9.00 — — — — — — 9.30 ∘ 2.36 23.12 Ex. 9 Comp. — 0.20 — — — — — — 0.20 ∘ 2.33 20.55 Ex. 15 Comp. — 1.00 — — — — — — 1.00 ∘ 2.34 20.47 Ex. 16 Comp. — 3.00 — — — — — — 3.00 ∘ 2.33 20.51 Ex. 17 Comp. — 6.00 — — — — — — 6.00 ∘ 2.43 20.53 Ex. 18 Comp. — 5.90 — — — 0.10 — — 6.00 ∘ 2.39 20.79 Ex. 20 Comp. — 8.00 — — — — — — 8.00 ∘ 2.46 20.81 Ex. 21 *.sup.1Concentration based on all metal components.

[0143] Referring to Tables 10 and 11, when the contact force and the opening force are increased, a DC high-voltage relay having a good arc property is obtained, and arc duration and arc energy tend to be reduced. This tendency was found not only in using the contact materials of the examples but also in using the contact materials not containing Zn (Comparative Examples 2, 3, 15 to 18, 20 and 21) and the contact materials having a high concentration of metal M (Comparative Examples 5 and 9). In comparison between an example and a comparative example having an equivalent content of metal M (amount of oxides) (for example, Example 5 and Comparative Example 18), however, it is understood that an effect of suppressing arc duration of 10% or more and arc energy of 5% or more is obtained in a DC high-voltage relay to which a contact material containing Zn is applied.

[0144] Besides, regarding a DC high-voltage relay to which the contact material having a high content of metal M is applied, arc duration and arc energy were larger than those of the examples. Although an arc property may be improved by increasing the contact force and the opening force in a DC high-voltage relay to which the contact material having a high content of metal M is applied, the problem of heat generation caused by contact resistance of the contact material is not solved.

INDUSTRIAL APPLICABILITY

[0145] The Ag oxide-based contact material that is applied in the DC high-voltage relay of the present invention exhibits an excellent arc discharge property, has low contact resistance, and generates a small amount of heat. The DC high-voltage relay of the present invention is free from the problems of arc discharge and heat generation at contact pair, and can perform reliable on/off control. The present invention is suitably applied to system main relays in power source circuits of high-voltage batteries in hybrid vehicles and the like, power conditioners in power supply systems such as solar power generation equipment, and the like.