JP2023100148A - Main circuit conductor and switchgear - Google Patents

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 The present disclosure relates to a main circuit conductor and a switch having a structure in which a contact is crimped to an energizing conductor.

A main circuit conductor constituting a fixed side contact conductor or a movable side contact conductor of a switch such as an electromagnetic switch or a circuit breaker includes an energizing conductor and a contact fixed to the energizing conductor. Silver alloys are often used for these contacts. For example, Ag-WC-Gr based sintered contacts and Ag-In ₂ O ₃ -SnO ₂ based fused contacts are used as silver alloy contacts, and these are selectively used depending on the rated current or breaking capacity. As for the method of joining the contact and the current-carrying conductor, there are methods such as caulking a rivet-shaped contact to the current-carrying conductor, and joining the current-carrying conductor and the contact with brazing material. Since the cost is lower, it is advantageous in terms of cost.

Patent Literature 1 discloses a structure for caulking and fixing to a rivet-shaped base metal.

JP-A-10-223076

Caulking is advantageous in terms of cost, but there is a problem that depending on the type of contact, cracks may occur or deformation may increase. For example, when a rivet-shaped sintered contact is crimped to a current-carrying conductor, the sintered contact cracks or deforms significantly. Such a contact suffers from the problem of lack of long-term reliability, such as contact chipping or contact falling off easily after thousands of impacts such as no-load endurance tests. Moreover, if the deformation is large, there is also the problem that the requirement of a thickness of 0.5 mm or more for the silver contact stipulated by the Electrical Appliance and Material Safety Law cannot be complied with.

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.

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 a hole, and a rivet-shaped contact that is inserted into the hole of the current-carrying conductor and crimped. Prepare. Let t be the thickness of ^the current-carrying conductor and d be the crimping allowance after the contact is crimped. Characterized by

According to the main circuit conductor of the present disclosure, it is possible to ensure long-term reliability.

Sectional view showing the trip state of the circuit breaker according to Embodiment 1 Sectional view showing the ON state of the circuit breaker according to Embodiment 1 FIG. 2 is a cross-sectional view showing the configuration of the rivet-shaped contact according to the first embodiment; FIG. 4 is a front view showing a state before the rivet contact is crimped to the current-carrying conductor according to the first embodiment; FIG. 4 is a front view showing a state after the rivet contact is crimped to the current-carrying conductor according to the first embodiment; FIG. 4 is a front view showing a state in which the rivet contact could not be appropriately crimped to the current-carrying conductor according to the first embodiment; 1 is a graph showing the results of a test in which a rivet contact is crimped to a current-carrying conductor in Embodiment 1, where the thickness of the current-carrying conductor is plotted on the horizontal axis and the crimping margin is plotted on the vertical axis, and the presence or absence of cracks occurring in the contact is shown. graph showing Sectional view showing the trip state of the double-break circuit breaker according to Embodiment 2 Sectional view showing the configuration of an electromagnetic switch according to Embodiment 3

A main circuit conductor and a switch according to embodiments will be described in detail below with reference to the drawings.

Embodiment 1.
FIG. 1 is a cross-sectional view showing a tripped state of the circuit breaker according to Embodiment 1. FIG. FIG. 2 is a cross-sectional view showing the ON state of the circuit breaker according to Embodiment 1. FIG.

1 and 2, the circuit breaker as a switch includes a handle 10, a switching mechanism 30, a fixed-side current-carrying conductor 6, and a fixed-side contact 7 provided on the fixed-side current-carrying conductor 6. , a movable-side current-carrying conductor 8 , and a movable-side contact 9 provided on the movable-side current-carrying conductor 8 . Since the details of the configuration of the opening/closing mechanism 30 are not the main part of the present disclosure, description thereof will be omitted.

As shown in FIGS. 1 and 2, when the handle 10 is turned on, the opening/closing mechanism 30 operates, the movable-side conductive conductor 8 is rotationally driven, the movable-side contact 9 abuts the fixed-side contact 7, The current-carrying conductor 8 on the fixed side and the current-carrying conductor 6 on the fixed side become conductive. At the moment when the movable side contact 9 contacts the fixed side contact 7 , the movable side contact 9 and the fixed side contact 7 are subjected to an impact due to the closing of the movable side contact 9 and the fixed side contact 7 . If the movable side contact 9 or the fixed side contact 7 is cracked by this impact, the crack progresses due to several thousand impacts such as a no-load endurance test, and the movable side contact 9 or the fixed side contact 7 is damaged. may occur, or the movable side contact 9 or the fixed side contact 7 may fall off.

FIG. 3 is a cross-sectional view showing the configuration of the rivet-shaped contact 20 according to the first embodiment. The rivet-shaped contact 20 is a general term for the movable side contact 9 or the fixed side contact 7 . The rivet-shaped contact 20 is hereinafter referred to as the rivet contact 20 . As shown in FIG. 3 , the rivet contact 20 has a base metal portion 1 having a rivet shape and a contact 2 joined to the base metal portion 1 . The base metal part 1 has a body part 1a without screws and a head part 1b having a larger diameter than the body part 1a. The boundary surface between the base metal part 1 and the contact 2 represents a joint 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.

The material of the base metal part 1 is, for example, copper, preferably pure copper such as oxygen-free copper or tough pitch copper. The material of the contact 2 is a silver-based alloy such as Ag--WC--Gr, Ag--WC, Ag--In ₂ O ₃ --SnO ₂ and Ag--SnO ₂ series. As described above, there are various types of materials for the base metal portion 1 and the contact points 2, and there are various types of methods for joining the base metal portion 1 and the contact points 2 together.

FIG. 4 is a front view showing a state before the rivet contact 20 is crimped to the conducting conductor 5 according to the first embodiment. FIG. 5 is a front view showing a state after the rivet contact 20 is crimped to the conducting conductor 5 according to the first embodiment. 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 conducting conductor 5 and the rivet contact 20 constitute the main circuit conductor. The material of the conducting conductor 5 is, for example, copper, aluminum, iron, or the like.

As shown in FIG. 4 , after inserting the trunk portion 1 a of the base metal portion 1 of the rivet contact 20 into the through hole 5 a provided in the conducting conductor 5 , the base metal of the rivet contact 20 projected from the conducting conductor 5 . A tool such as a punch 11 is used to apply force to the front end surface 1c of the body portion 1a of the portion 1, thereby performing caulking.

As a result, as shown in FIG. 5, the front end portion 1d of the trunk portion 1a of the base metal portion 1 projecting from the conducting conductor 5 is deformed, and caulking is performed. Let t be the thickness of the current-carrying conductor 5, and d be the distance from the tip surface 1e of the rivet contact 20 to the current-carrying conductor 5 after crimping. Hereinafter, d is referred to as caulking allowance. If the tip surface 1e of the rivet contact 20 after crimping is not flat, the caulking allowance d is determined based on the average position of each tip point forming the tip surface 1e.

FIG. 6 is a front view showing a state in which the rivet contact 20 could not be appropriately crimped onto the conducting conductor 5 according to the first embodiment. As shown in FIG. 6, if the caulking allowance d is too long, only the vicinity of the front end surface 1c of the trunk portion 1a of the base metal portion 1 swells, so that the portion of the through hole 5a of the conducting conductor 5 does not swell, and the base metal portion does not swell. 1 moves relative to the current-carrying conductor 5, and the rivet contact 20 cannot be crimped with an appropriate crimping strength.

FIG. 7 is a graph showing the results of a test of crimping the rivet contact 20 to the current-carrying conductor 5 in Embodiment 1. , and the presence or absence of cracks occurring in the contact 2. FIG. The unit of the caulking allowance d is mm, and the unit of the thickness t of the conducting conductor 5 is mm. The conducting conductor 5 was made of copper, and the contact 2 was made of Ag (85 wt %)-WC (12 wt %)-Gr (3 wt %). wt% is percent by weight. During caulking, the contact 2 expands slightly and the diameter of the contact 2 increases. A circle mark indicates that there is no contact crack that can be visually confirmed, and a cross mark indicates that there is a contact crack that can be visually confirmed. A threshold value a1 indicated by a white triangle is a threshold value for identifying whether or not there is a contact crack. If the crimping amount d is larger than the threshold value a1, there is a possibility that contact cracks will occur. If the crimping amount d is smaller than the threshold value a1, there is no possibility that contact cracks will occur. A threshold value a2 indicated by a black triangle is a threshold value for determining whether or not the crimping force becomes loose. When the caulking allowance d is smaller than the threshold value a2, the required caulking force is obtained.

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 is visually confirmed that the contact 2 does not crack. bottom.
t×(d ^1.4 )>2.3 (1)

As a result, when the thickness t of the current-carrying conductor 5 is thin, the force at the time of crimping is easily transmitted to the contact 2, so it is necessary to crimp shallowly (that is, the crimping margin d is large), but the current-carrying conductor 5 When the thickness t of is large, it becomes difficult for the force of crimping to be transmitted to the contact 2, so that it is possible to crimp deeply (that is, the crimping margin d is small).

Further, when d+t≧4.7 as indicated by the threshold value a2, as shown in FIG. 6, the crimping force becomes loose and the contact stability is impaired, so that it cannot be used as a main circuit conductor. showing. Therefore, in order to obtain an appropriate crimping strength, the sum of the thickness t and the crimping allowance d of the conducting conductor 5 must be less than 4.7 mm, as shown in the following formula (2).
d+t<4.7 (2)

When a main circuit conductor that satisfies formula (1) is installed in a circuit breaker or a switch such as an electromagnetic switch, it can withstand thousands of impacts such as a no-load endurance test, resulting in long-term reliability. can be ensured.

In the case of a contact having a Vickers hardness of 160 HV or less, if the formula (1) is not satisfied, the contact 2 is likely to be deformed when the rivet contact 20 is crimped. It does not satisfy the 0.5 mm or larger contact requirement for silver alloy contacts set forth in the law.

In addition, when the sintered contact contains tungsten carbide, it is weaker against the impact of caulking and cracks more easily than the silver-based alloy contact described above, and the effect of formula (1) is more pronounced. appear in In particular, when the content of tungsten carbide is 40 wt% or less, if the expression (1) is not satisfied, the contact 2 tends to deform when the rivet contact 20 is crimped. It does not satisfy the 0.5 mm or larger contact requirement for silver alloy contacts set forth in the law. In addition, although the sintered contact is normally joined to the current-carrying conductor by brazing, in the first embodiment, the rivet shape, which is less expensive than brazing, is used to suppress the temperature rise during the current flow, It is possible to take advantage of the characteristics of sintered contacts with excellent welding performance.

In addition, when the sintered contact contains graphite, it is weaker against the impact force of caulking than the silver-based alloy contact described above, and cracks are more likely to occur, and the effect of formula (1) appears more remarkably. . In particular, when the graphite content is 2% or more, the effect of formula (1) is more pronounced, and it can withstand thousands of impacts such as a no-load endurance test, ensuring long-term reliability. be able to. Furthermore, it is possible to take advantage of the characteristics of the sintered contact, which is inexpensive, has a rivet shape, suppresses a temperature rise when energized, and has excellent welding performance of the contact.

In addition, tungsten carbide and graphite may be contained in the contact 2. Even in this case, the characteristics of the sintered contact, which is an inexpensive rivet shape, suppresses the temperature rise when energized, and has excellent welding performance of the contact, are utilized. be able to.

As described above, according to Embodiment 1, where t is the thickness of the conducting conductor 5 and d is the crimping allowance after the rivet contact 20 is crimped, t×(d ^1.4 )>2. 3 and satisfies d+t<4.7 mm, so that cracks do not occur in the contacts, and the contacts do not tend to fall off, so long-term reliability of the main circuit conductor can be ensured. .

Embodiment 2.
Embodiment 1 described an example of a single-break circuit breaker. It is applied to the circuit breaker of FIG. 8 is a cross-sectional view showing a trip state of the double-break circuit breaker according to the second embodiment.

As shown in FIG. 8, the circuit breaker includes, as fixed contacts, a first fixed contact 40 as an energizing conductor, a first fixed contact 41 provided on the first fixed contact 40, and a and a second fixed contact 43 provided on the second fixed contact 42 . In addition, the circuit breaker shown in FIG. A second movable contact 52 and a second movable contact 53 provided on the second movable contact 52 are provided. The first movable contact 50 and the second movable contact 52 are integral structures supported by the rotary shaft 54 of the rotor 55 and extend in opposite directions. When the rotor 55 rotates clockwise from the state shown in FIG. , the second movable contact 53 contacts the second fixed contact 43, and the circuit breaker becomes conductive.

The main circuit conductor having the rivet contact 20 and current-carrying conductor 5 described in detail in the first embodiment can be used as the fixed contact and the movable contact of the double-break circuit breaker shown in FIG.

Embodiment 3.
In the third embodiment, the main circuit conductor having the rivet contact 20 and the conducting conductor 5 described in the first embodiment is applied to an electromagnetic switch. 9 is a cross-sectional view showing the configuration of an electromagnetic switch according to Embodiment 3. FIG.

An electromagnetic switch as a switch includes, as fixed contacts, a first fixed contact 60 as an energizing conductor, a first fixed contact 61 provided on the first fixed contact 60, and a second energizing conductor. A fixed contact 62 and a second fixed contact 63 provided on the second fixed contact 62 are provided. As movable contacts, the electromagnetic switch has a first movable contact 70 as an energizing conductor, a first movable contact 71 provided on the first movable contact 70, and a second movable contact 72 as an energizing conductor. and a second movable contact 73 provided on the second movable contact 72 . The first movable contact 70 and the second movable contact 72 are integral structures supported by a plunger 74 of an electromagnetic actuator 75 and extend in opposite directions. From the state shown in FIG. 9 , the electromagnetic actuator 75 has a fixed core 76 and a movable core 77 , and the fixed core 76 attracts the movable core 77 when the coil 78 is energized. A 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, thereby bringing the first movable contact 71 into contact with the first fixed contact 61 and the second movable contact 73 into contact with the second fixed contact 63. , the electromagnetic switch becomes conductive.

The main circuit conductor having the rivet contact 20 and conducting conductor 5 detailed in the first embodiment can be used as the fixed contact and movable contact of the electromagnetic switch shown in FIG.

The configuration shown in the above embodiment shows an example of the content of the present disclosure, and can be combined with another known technology. It is also possible to omit or change the part.

Reference Signs List 1 base metal part 1a trunk part 1b head part 1c, 1e tip surface 1d tip part 2 contacts 3 joining surfaces 5, 6, 8 energizing conductors 5a through holes 7 stationary contacts 9 movable side contact, 10 handle, 11 punch, 20 rivet-shaped contact (rivet contact), 30 switching mechanism, 40, 60 first fixed contact, 41, 61 first fixed contact, 42, 62 second fixed contact, 43, 63 second fixed contact, 50, 70 first movable contact, 51, 71 first movable contact, 52, 72 second movable contact, 53, 73 second movable contact, 54 rotating shaft, 55 rotor, 74 Plunger, 75 Electromagnetic actuator, 76 Fixed core, 77 Movable core, 78 Coil, d Crimping allowance, t Thickness of conducting conductor.

Claims (7)

a current-carrying conductor provided with a hole;
a rivet-shaped contact that is inserted into the hole of the conducting conductor and crimped;
with
When the thickness of the conducting conductor is t and the crimping allowance after crimping the contact is d,
t×(d ^1.4 )>2.3 and d+t<4.7 mm
A main circuit conductor characterized by satisfying 2. The main circuit conductor according to claim 1, wherein said contact has a Vickers hardness of 160 HV or less. 3. A main circuit conductor as claimed in claim 1 or 2, characterized in that the contacts are sintered contacts and contain tungsten carbide. 4. The main circuit conductor according to claim 3, wherein the contact has a tungsten carbide content of 40% by weight or less. 5. A main circuit conductor as claimed in any one of claims 1 to 4, characterized in that the contacts are sintered contacts and contain graphite. 6. The main circuit conductor of claim 5, wherein said contact contains at least 2% by weight of said graphite. A switch using the main circuit conductor according to any one of claims 1 to 6.

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