Main circuit conductor and switch

Abstract

To obtain a main circuit conductor capable of securing long-term reliability.SOLUTION: A main circuit conductor comprises: a power conduction conductor 5 provided with a penetration hole 5a; and a rivet contact point 20 that is inserted into the penetration hole 5a of the power conduction conductor 5, and is caulked. When a thickness of the power conduction conductor 5 is t, and a caulking margin obtained after the rivet contact point 20 is caulked is d, t×(d1.4)>2.3 and d+t<4.7 mm are satisfied.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a main circuit conductor and a switch having a structure in which a contact is caulked to a current-carrying conductor.

Background Art

[0002] The main circuit conductor constituting the fixed-side contact conductor or the movable-side contact conductor of a switch such as an electromagnetic switch or a circuit breaker includes a current-carrying conductor and a contact fixed to the current-carrying conductor. Silver alloys are often used for these contacts. For example, Ag-WC-Gr-based sintered contacts, Ag-In2O3-SnO2-based fused contacts, etc. are used as silver alloy contacts, and these are properly selected according to the rated current or breaking capacity. Also, regarding the joining method between the contact and the current-carrying conductor, there are those that caulking-join a rivet-shaped contact to the current-carrying conductor, those that join the current-carrying conductor and the contact with a brazing material, etc. However, caulking-joining is more cost-effective, so it is advantageous in terms of cost.

[0003] Patent Document 1 shows a caulking and fixing structure for a rivet-shaped base metal.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Caulking joints are cost-effective, but depending on the type of contact, there are problems such as cracking or excessive deformation. For example, when caulking a rivet-shaped sintered contact onto a current-carrying conductor, the sintered contact may crack or deform significantly. With such contacts, when subjected to impacts in the thousands, such as in a no-load endurance test, chipping may occur at the contact or the contact may become prone to falling off, resulting in problems with long-term reliability. Also, if the deformation is large, there is a problem that the requirement of a silver contact thickness of 0.5 mm or more defined by the Electrical Appliance and Material Safety Act cannot be met.

[0006] The present disclosure has been made in view of the above, and an object thereof is to obtain a main circuit conductor capable of ensuring long-term reliability.

Means for Solving the Problems

[0007] In order to solve the above-described problems and achieve the object, the main circuit conductor of the present disclosure includes a current-carrying conductor provided with holes and a rivet-shaped contact inserted into the holes of the current-carrying conductor and caulked. When the thickness of the current-carrying conductor is t and the caulking allowance after the contact is caulked is d, t×(d 1.4 )>2.3 and d + t < 4.7 mm are satisfied And, when the thickness t of the energizing conductor becomes thin, determine the caulking allowance d so that the caulking allowance d becomes large This is a feature.

Advantages of the Invention

[0008] According to the main circuit conductor of the present disclosure, there is an effect that long-term reliability can be ensured.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0010] Hereinafter, the main circuit conductor and the switch according to the embodiment will be described in detail with reference to the drawings.

[0011] Embodiment 1. FIG. 1 is a cross-sectional view showing the trip state of a circuit breaker according to Embodiment 1. FIG. 2 is a cross-sectional view showing the on state of the circuit breaker according to Embodiment 1.

[0012] In FIGS. 1 and 2, the circuit breaker as the switch includes a handle 10, an opening / closing mechanism unit 30, a fixed-side energizing conductor 6, a fixed-side contact 7 provided on the fixed-side energizing conductor 6, a movable-side energizing conductor 8, and a movable-side contact 9 provided on the movable-side energizing conductor 8. Details of the configuration of the opening / closing mechanism unit 30 will not be described as they are not a main part of the present disclosure.

[0013] As shown in FIGS. 1 and 2, when the handle 10 is turned on, the opening / closing mechanism unit 30 operates, the energizing conductor 8 on the movable side is rotationally driven, the movable contact 9 comes into contact with the fixed contact 7, and the energizing conductor 8 on the movable side and the energizing conductor 6 on the fixed side are in a conductive state. At the moment when the movable contact 9 contacts the fixed contact 7, an impact due to the engagement of the movable contact 9 and the fixed contact 7 is applied to the movable contact 9 and the fixed contact 7. Due to this impact, if a crack occurs in the movable contact 9 or the fixed contact 7, the crack progresses due to thousands of impacts such as a no-load endurance test, and a defect may occur in the movable contact 9 or the fixed contact 7, or the movable contact 9 or the fixed contact 7 may fall off.

[0014] FIG. 3 is a cross-sectional view showing the configuration of the rivet-shaped contact 20 according to Embodiment 1. The rivet-shaped contact 20 is a general term for the movable contact 9 or the fixed contact 7. Hereinafter, the rivet-shaped contact 20 is referred to as the rivet contact 20. As shown in FIG. 3, the rivet contact 20 has a base metal part 1 having the shape of a rivet and a contact 2 joined to the base metal part 1. The base metal part 1 has a body part 1a without a screw and a head part 1b having a diameter larger than that of the body part 1a. The boundary surface between the base metal part 1 and the contact 2 indicates a joining surface 3 where the base metal part 1 and the contact 2 are joined by brazing, cold pressure welding, hot pressure welding, or the like.

[0015] The material of the base metal part 1 is, for example, copper, and pure copper such as oxygen-free copper or tough pitch copper is desirable. The material of the contact 2 is a silver-based alloy, for example, Ag-WC-Gr, Ag-WC, Ag-In2O3-SnO2, or Ag-SnO2-based. Thus, there are various types of materials for the base metal part 1 and the contact 2, and there are also various types of joining methods for the base metal part 1 and the contact 2.

[0016] FIG. 4 is a front view showing a state before caulking the rivet contact 20 to the current-carrying conductor 5 according to Embodiment 1. FIG. 5 is a front view showing a state after caulking the rivet contact 20 to the current-carrying conductor 5 according to Embodiment 1. The current-carrying conductor 5 is a general term for the fixed-side current-carrying conductor 6 and the movable-side current-carrying conductor 8. The main circuit conductor is constituted by the current-carrying conductor 5 and the rivet contact 20. The material of the current-carrying conductor 5 is, for example, copper, aluminum, iron, or the like.

[0017] As shown in FIG. 4, after inserting the body portion 1a of the base metal portion 1 of the rivet contact 20 into the through hole 5a provided in the current-carrying conductor 5, a force is applied to the tip surface 1c of the body portion 1a of the base metal portion 1 of the rivet contact 20 protruding from the current-carrying conductor 5 by a tool such as a punch 11 to perform caulking.

[0018] Thereby, as shown in FIG. 5, the tip portion 1d of the body portion 1a of the base metal portion 1 protruding from the current-carrying conductor 5 is deformed, and caulking joining is performed. Let the thickness of the current-carrying conductor 5 be t, and the distance from the tip surface 1e of the rivet contact 20 after caulking to the current-carrying conductor 5 be d. Hereinafter, d is referred to as the caulking allowance. When the tip surface 1e of the rivet contact 20 after caulking is not flat, the caulking allowance d is determined based on the average position of each tip point constituting the tip surface 1e.

[0019] FIG. 6 is a front view showing a state in which the rivet contact 20 cannot be properly caulked to the current-carrying conductor 5 according to Embodiment 1. As shown in FIG. 6, when the caulking allowance d is too long, only the vicinity of the tip surface 1c of the body portion 1a of the base metal portion 1 bulges, so the portion of the through hole 5a of the current-carrying conductor 5 does not bulge, and the base metal portion 1 moves with respect to the current-carrying conductor 5, and the rivet contact 20 cannot be caulked with appropriate caulking strength.

[0020] FIG. 7 is a graph showing the results of a test of caulking the rivet contact 20 to the current-carrying conductor 5 in Embodiment 1. The horizontal axis represents the thickness t of the current-carrying conductor 5, the vertical axis represents the caulking allowance d, and it is a graph showing the presence or absence of cracks generated at the contact point 2. The unit of the caulking allowance d is mm, and the unit of the thickness t of the current-carrying conductor 5 is mm. The current-carrying conductor 5 is made of copper, and the contact point 2 is made of Ag(85wt%)-WC(12wt%)-Gr(3wt%). wt% is weight percent. During caulking, the contact point 2 expands slightly and the diameter of the contact point 2 increases, but in this test, caulking was performed without restraining the outer periphery of the contact point 2. The ○ mark indicates a state without contact point cracks that can be visually confirmed, and the × mark indicates the presence of contact point cracks that can be visually confirmed. Also, the threshold value a1 indicated by the white-filled triangle is a threshold value for discriminating whether there are contact point cracks or not. When the caulking allowance d is Small greater than the threshold value a1, there is a possibility of the occurrence of contact point cracks, and when the caulking allowance d is Large less than the threshold value a1, there is no possibility of the occurrence of contact point cracks. The threshold value a2 indicated by the black-filled triangle is a threshold value for determining whether the caulking force becomes loose or not. When the caulking allowance d becomes larger than the threshold value a2, the caulking force becomes loose and an appropriate caulking force cannot be obtained. When the caulking allowance d is smaller than the threshold value a2, the required caulking force can be obtained.

[0021] According to the test results in FIG. 7, when the value of t×(d 1.4 ) is greater than 2.3, that is, when the following formula (1) holds, it was visually confirmed that no cracks occurred at the contact point 2. t×(d 1.4 )>2.3 ·····(1)

[0022] This result indicates that when the thickness t of the current-carrying conductor 5 is thin, the force during caulking is likely to be transmitted to the contact point 2, so it is necessary to caulk shallowly (that is, increase the caulking allowance d). When the thickness t of the current-carrying conductor 5 is thick, the caulking force is less likely to be transmitted to the contact point 2, so it can be caulked deeply (that is, decrease the caulking allowance d).

[0023] Also, as indicated by the threshold value a2, when d + t ≥ 4.7, as shown in FIG. 6, the caulking force becomes loose and the contact stability is impaired, indicating that it cannot be used as the main circuit conductor. Therefore, in order to obtain an appropriate caulking strength, as shown in the following formula (2), it is necessary to make the sum of the thickness t of the energizing conductor 5 and the caulking allowance d smaller than 4.7 mm. d + t < 4.7 ·····(2)

[0024] When the main circuit conductor satisfying formula (1) is mounted on a switch such as a circuit breaker or an electromagnetic switch, it can withstand thousands of impacts such as a no-load endurance test, and long-term reliability can be ensured.

[0025] Also, in the case of a contact with a Vickers hardness of 160 HV or less, if formula (1) is not satisfied, the contact 2 is likely to be deformed when the rivet contact 20 is caulked, and depending on the shape of the contact 2, for example, in the case of a silver alloy contact defined by the Electrical Appliance and Material Safety Act, it does not satisfy the contact requirement of 0.5 mm or more.

[0026] Also, when tungsten carbide is contained in the sintered contact, compared with the above-mentioned silver-based alloy contact, it is weaker against the caulking impact force and more likely to crack, and the effect of formula (1) appears more significantly. In particular, when the content of tungsten carbide is 40 wt% or less, if formula (1) is not satisfied, the contact 2 is likely to be deformed when the rivet contact 20 is caulked, and depending on the shape of the contact 2, for example, in the case of a silver alloy contact defined by the Electrical Appliance and Material Safety Act, it does not satisfy the contact requirement of 0.5 mm or more. Also, usually, in the sintered contact, the contact is joined to the energizing conductor by brazing, but in Embodiment 1, in a rivet shape that is less expensive than brazing, the temperature rise during energization can be suppressed, and the characteristics of the sintered contact with excellent welding performance of the contact can be utilized.

[0027] Furthermore, when sintered contacts contain graphite, they are weaker against the impact force of crimping compared to the aforementioned silver-based alloy contacts, and cracks occur more easily, so the effect of formula (1) becomes more pronounced. In particular, when the graphite content is 2% or more, the effect of formula (1) becomes more pronounced, and the contacts can withstand thousands of impacts such as those in no-load durability tests, ensuring long-term reliability. Furthermore, the sintered contacts can be made in an inexpensive rivet shape, suppressing temperature rise during current flow, and taking advantage of the characteristics of the sintered contacts, which have excellent welding performance.

[0028] Furthermore, the contact 2 may contain tungsten carbide and graphite. In this case, the characteristics of sintered contacts, such as an inexpensive rivet shape, suppressing temperature rise during current application, and excellent contact welding performance, can be utilized.

[0029] In this way, according to the first embodiment, when the thickness of the current-carrying conductor 5 is t and the crimping allowance after the rivet contact 20 is crimped is d, t×(d 1.4 ) > 2.3 and d + t < 4.7 mm, cracks do not occur in the contacts and the contacts do not become easily detached, ensuring the long-term reliability of the main circuit conductor.

[0030] Embodiment 2 In the first embodiment, an example of a single-break circuit breaker has been described, but in the second embodiment, the main circuit conductor having the rivet contact 20 and the current-carrying conductor 5 described in the first embodiment is applied to a double-break circuit breaker. Fig. 8 is a cross-sectional view showing the tripped state of the double-break circuit breaker according to the second embodiment.

[0031] As shown in FIG. 8, the circuit breaker includes, as fixed contacts, a first fixed contact 40 as a current-carrying conductor, a first fixed contact point 41 provided on the first fixed contact 40, a second fixed contact 42 as a current-carrying conductor, and a second fixed contact point 43 provided on the second fixed contact 42. Further, the circuit breaker shown in FIG. 8 includes, as movable contacts, a first movable contact 50 as a current-carrying conductor, a first movable contact point 51 provided on the first movable contact 50, a second movable contact 52 as a current-carrying conductor, and a second movable contact point 53 provided on the second movable contact 52. The first movable contact 50 and the second movable contact 52 are an integral structure supported by the rotating shaft 54 of the rotor 55 and extend in opposite directions to each other. When the rotor 55 rotates clockwise from the state shown in FIG. 8, the first movable contact 50 and the second movable contact 52 rotate clockwise, the first movable contact point 51 abuts against the first fixed contact point 41, the second movable contact point 53 abuts against the second fixed contact point 43, and the circuit breaker becomes conductive.

[0032] The main circuit conductor having the rivet contact 20 and the current-carrying conductor 5 detailed in Embodiment 1 can be used as the fixed contacts and the movable contacts of the two-point cut-off circuit breaker shown in FIG. 8.

[0033] Embodiment 3. Embodiment 3 applies the main circuit conductor having the rivet contact 20 and the current-carrying conductor 5 described in Embodiment 1 to an electromagnetic switch. FIG. 9 is a cross-sectional view showing the configuration of the electromagnetic switch according to Embodiment 3.

[0034] As an electromagnetic switch, as fixed contacts, it includes a first fixed contact 60 as a current-carrying conductor, a first fixed contact point 61 provided on the first fixed contact 60, a second fixed contact 62 as a current-carrying conductor, and a second fixed contact point 63 provided on the second fixed contact 62. The electromagnetic switch includes, as movable contact points, a first movable contact 70 as a current-carrying conductor, a first movable contact point 71 provided on the first movable contact 70, a second movable contact 72 as a current-carrying conductor, and a second movable contact point 73 provided on the second movable contact 72. The first movable contact 70 and the second movable contact 72 are an integral structure supported by the plunger 74 of the electromagnetic actuator 75 and extend in opposite directions to each other. From the state shown in FIG. 9, the electromagnetic actuator 75 has a fixed iron core 76 and a movable iron core 77, and when a current is passed through the coil 78, the fixed iron core 76 attracts the movable iron core 77. The plunger 74 is attached to the movable iron core 77. When the electromagnetic actuator 75 operates, the fixed iron core 76 attracts the movable iron core 77, whereby the first movable contact point 71 abuts against the first fixed contact point 61, the second movable contact point 73 abuts against the second fixed contact point 63, and the electromagnetic switch becomes conductive.

[0035] The main circuit conductor having the rivet contact 20 and the current-carrying conductor 5 detailed in the first embodiment can be used as the fixed contacts and movable contacts of the electromagnetic switch shown in FIG. 9.

[0036] The configurations shown in the above embodiments are examples of the content of the present disclosure, and it is possible to combine them with other known technologies, and it is also possible to omit or change a part of the configuration without departing from the gist of the present disclosure.

Explanation of reference numerals

[0037] 1 metal part, 1a body part, 1b head part, 1c, 1e tip surface, 1d tip part, 2 contact point, 3 joint surface, 5, 6, 8 conductors for energization, 5a through hole, 7 fixed-side contact point, 9 movable-side contact point, 10 handle, 11 punch, 20 rivet-shaped contact point (rivet contact), 30 opening / closing mechanism part, 40, 60 first fixed contact, 41, 61 first fixed contact point, 42, 62 second fixed contact, 43, 63 second fixed contact point, 50, 70 first movable contact, 51, 71 first movable contact point, 52, 72 second movable contact, 53, 73 second movable contact point, 54 rotation axis, 55 rotor, 74 plunger, 75 electromagnetic actuator, 76 fixed core, 77 movable core, 78 coil, d caulking allowance, t thickness of conductor for energization.

Claims

1. A current-carrying conductor provided with a hole, A rivet-shaped contact inserted into the hole of the current-carrying conductor and caulked, Comprising, When the thickness of the current-carrying conductor is t and the caulking allowance after the contact is caulked is d, t × (d １．４ ) > 2.3 and d + t < 4.7 mm Satisfying, The caulking allowance d is determined such that as the thickness t of the current-carrying conductor becomes thinner, the caulking allowance d becomes larger. The main circuit conductor is characterized by this.

2. The main circuit conductor according to claim 1, wherein the contact has a Vickers hardness of 160 HV or less.

3. The main circuit conductor according to claim 1 or 2, wherein the contact is a sintered contact and contains tungsten carbide.

4. The main circuit conductor according to claim 3, wherein the content rate of the tungsten carbide in the contact is 40% by weight or less.

5. The main circuit conductor according to any one of claims 1 to 4, wherein the contact is a sintered contact and contains graphite.

6. The main circuit conductor according to claim 5, wherein the contact contains 2% by weight or more of the graphite.

7. A switch characterized by using the main circuit conductor according to any one of claims 1 to 6.

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