JPS6154131A - Contactor structure of switching device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a contact structure of a switching device such as a relay, contactor, switch, etc.

[Background Art] In switching devices such as relays, contactors, switches, and notches used with a rated current of around 1 to 30 A, welding resistance due to rush current is a bigger problem than contact wear. The actual loads on the contacts in this rated current range are small motors, solenoids, various lamps, etc., and all of these have a voltage of 5 to 1
00 times the rush current flows. By the way, contact welding in a switchgear occurs during the closing (contact) operation, due to mechanical vibration due to collision between contacts, arc generated due to bounce caused by electromagnetic repulsion caused by the current, or Joule heat due to current concentration at the contact part. arise. That is, as the rush current increases, the risk of contact welding increases accordingly. Therefore, switching devices used for loads with large rush currents have been dealt with by increasing the contact pressure, contact release force, contact shape, etc., or by installing current limiting reactors or the like outside the switching device.

[Object of the Invention] The present invention has been made in view of the above points, and its purpose is to provide a contact structure for a switchgear that can improve the welding resistance of contacts due to rush current. .

[Disclosure of the Invention] The contact structure of the switchgear according to the present invention is such that one end is joined to the base and the middle part is joined to the movable contact, and the movable contact is attached with a spring so as to resist the driving force of the electromagnetic drive member. At the same time, a coil spring is provided whose other end faces the fixed contact, and when both the fixed and movable contacts are in contact, the coil spring forms an electric path in parallel with the fixed and movable contacts, and when the both contacts connect and separate. It is characterized in that an electric path is formed in advance during the contact operation, and the electric path is cut off after a delay during the disconnection operation.

(Example) An example of the present invention will be described below based on FIGS. 1 to 6.

FIG. 1 shows a hinge-type relay in which the contact structure of the present invention is used. This relay has a fixed contact 4 (exposed from the base 2) having a fixed contact 3 mounted on a base 2 that constitutes a housing together with a cover 1. The housing has a movable contact terminal 5 and a coil terminal 6 fixed therethrough, and has a movable contact 7 that contacts the fixed contact 3 and a contact 11, and is attached to the electromagnetic drive member. The attached movable contact 8 is accommodated therein. The main parts of the present invention include a device stand 2, a fixed contact 4, a movable contact 8, an electromagnetic drive member, and a coil spring to be described later.

The fixed contact 4 has a contact fixing piece 4a that fixes the fixed contact 3.
, is bent to have a terminal piece 4b that is fixedly fixed through the container base 2 and exposed outside the housing, and an intermediate piece 4c that connects these pieces. In addition, each of these pieces 4a, 4b, 4c
may be formed into a simple flat plate shape.

The electromagnetic drive member includes a U-shaped yoke 9, a fixed iron core 10 with one end fixed to the connecting piece of the yoke 9, a coil 11 wound around the fixed iron core 10, and a base end that can be freely angularly displaced at the end of the yoke 9. It consists of an amatia 12 which is supported by the fixed iron core 10 and whose tip faces the other end suction surface of the fixed iron core 10. In a normal electromagnetic drive member, the amatia 12 is further provided with a return spring that is biased in a direction away from the attraction surface of the fixed iron core 10, but this is not necessary in the present invention. 13 is a piece attached to the yoke 9 to prevent the amatia 12 from falling off.

The movable contact 8 is formed of an elastic material into a long plate shape, has the movable contact 7 fixed to an intermediate portion 8a, and has its base end attached to the distal end of the amatia 12 via an insulating holder 14.

Reference numeral 15 denotes a coil spring having a predetermined number of turns and free length, and is made of piano wire, stainless steel wire, or copper-based spring material (for example, Be-Cu), and one end 15a is connected to the instrument stand 2.
The intermediate portions 15b are joined to the tips 8b of the movable contact 8 to the rising pieces of the spring locking portion 2a projecting from the bottom of the spring in an L-shape, so that the movable contact 8 resists the driving force of the electromagnetic drive member. The other end 15c faces the contact fixing piece 4a of the fixed contact 4. Figure 1 shows a steady state in which the coil 11 of the electromagnetic drive member is not excited! 3(
(contact open state), the amachia 12 is stopped at the right position by the coil spring 15, and in this case, the middle part 15b of the coil spring 15 and the other end 15C are in a self-height shape, and the other end 15C A gap g1 exists between the contact fixing piece 4a of the fixed contact 4 and the contact fixing piece 4a of the fixed contact 4. This gap g1 is set to be slightly smaller than the gap g2 between both contacts 3.7. In the excitation state (contact contact state) in which the coil 11 is excited from the steady state shown in FIG. , 7 are brought into contact, but both contacts 3 and 7 come into contact during the suction operation. The movement of the amatia 12 after entering this contact state causes the movable contact 8 to flex, and the resulting spring force acts as contact pressure between the two contacts 3.7.

Further, the coil spring 15 forms an electric path in parallel with both contacts 3 and 7 when they are in contact with each other, and also forms an electric path in parallel with the above-mentioned gap et, [2]. form an electric path and open it! 9
11I cut off the electric circuit late during the first crop. The predetermined number of turns and free length of the coil spring 15 are determined by taking these points into consideration.

A lead wire 16 connects the movable contact θ and the movable contact terminal 15.

(Operation) FIG. 2 is a side view of the main parts showing the operating state, and (a) is in a steady state (contact open state) where the coil 11 is not excited, as in FIG. 1.

When the coil 11 is excited in this state, the coil spring 15
The amachia 12 is attracted against the spring force applied between the one end 15a and the intermediate portion 15b, and the movable contact 8 is (
Start moving in the direction of arrow A in a). As a result of this movement, first, the other end 15c of the coil spring 15 and the contact fixing piece 4a of the fixed contact 4 come into contact with each other in advance of both contacts 3.7 to form an electric path 11, as shown in (b). Further, as the movable contactor 8 moves in the direction of arrow A, both contacts 3 and 7 come into contact with each other as shown in (c), and an electric path 12 is also formed. In this state, the electric line i1.
+2 are formed in parallel, but since the resistance of the electric line 12 is smaller, the current ■ mainly flows through the electric line 12. Sufficient contact pressure is applied to both contacts 3 and 7 by the spring force of the movable contact 8.

Next, when the excitation of the coil 11 is extinguished in this state, the amatia 12 is connected to the one end 15a of the coil spring 15 and the intermediate part 15b.
The movable contact 8 returns due to the spring force between (d)
When moving in the direction of arrow B, first both contacts 3.7 are opened and only the electric circuit 11 is formed, and then the other end 1 of the coil spring 15 is opened.
5G and the contact fixing piece 4a of the fixed contact 4 are separated e)
, that is, the state returns to the state shown in FIG.

Here, a comparison will be made between a device in which a coil spring 15 is provided as in the present invention and a conventional device in which the coil spring 15 is not provided.

■ The current 1a of the main current in the contact/separation operation of the contact part forms a curve as shown in Fig. 3, and the second
Each point in time in FIGS. (a) to (e) is shown with the time axis at the top. On the other hand, the current Ib of the conventional one is when the contacts are in contact (Co
A rush current flows from point ), then a steady current flows, and at point (d') when the contacts open, no current flows. This shows that the rush current of Ia is significantly suppressed compared to rb. That is, from time (b) to time (c), the resistance of the coil spring 15 acts,
Moreover, it also acts as a reactor for several hundred μs.
An effective current limiting effect is obtained for capacitor loads reaching several kA during cc. This also suppresses electromagnetic repulsion due to rush current. To is a period in which contact bounce occurs during contact operation.

■ Behavior during contact/separation motion of the contact portion The load Pra of the movable contact 8 of the proposed model forms a curve as shown in Fig. 4, and each point in Fig. 2 (a) to (e) is shown on the stroke axis X. It is. On the other hand, the conventional load Prb is smaller than Pra in the section (b) to (C) due to the absence of the coil spring 15. Prc is a load that drives the movable contact 8, such as the attractive force of the coil 11, and Prc-Pra or Prc-Prb is applied to the movable contact 8. From this, the proposed coil 11
When the coil 11 is energized and performs a contact operation, the coil spring 15 acts as a buffer against the collision of the movable contact 7, and conversely, when the excitation of the coil 11 disappears and the opening operation is performed, Prc is zero, so the coil It can be seen that the spring 15 acts to increase the tripping force of the movable contact 7.

Furthermore, looking at the influence of the above-mentioned action on the contact pressure during contact operation and the contact/separation state of contacts 3 and 7, the contact pressure Pa of the present invention forms a curve as shown in Fig. 5, indicating that the contact/separation state is Curve A has fewer peaks.

On the other hand, the contact pressure pb of the conventional one has a larger amplitude than Pa, and the curve B showing the contact 1i1+1 state has many peaks. Therefore, the bounce of the contact point in the present invention is reduced.

Also, looking at the My effect on the arc current and arc voltage during the opening operation, we find that the arc current i
a forms a curve as shown in FIG. 6(a), on the other hand, the arc current tb of the conventional one flows for a longer time than ia, and the arc voltage va of the proposed one forms a curve as shown in FIG. 6(b); on the other hand, The conventional arc voltage vb is raised slower than va. Therefore, the coil spring 13 of the present invention serves as a kind of arc tip, and damage to the contacts due to arc can be reduced.

As described above, the proposed method suppresses the rush current, lowers the Joule heat at the contact part, reduces bounce during contact operation, and furthermore reduces the occurrence of arcs during the opening operation. be.

Note that when the coil spring 15 is formed of a shape memory alloy,
Even better effects can be achieved. In other words, the shape memory alloy coil spring has a spring load similar to that of the previous embodiment until it exceeds a predetermined transformation point temperature, and once the transformation point temperature is exceeded, the spring load is reduced such that, for example, the free length is shortened. Set it so that it is small. However, the load Prd on the movable contact in this case forms a curve as shown in Fig. 7, but if we look at it in relation to Pra, Prb + Prc in the previous example, we can see that the coil spring has a lash during contact operation. If the frequency of the current is high, the transformation point temperature will not be exceeded due to its heat capacity, and therefore it will work similarly to that of the previous embodiment, but if the frequency of the rush current is low, the transformation point temperature will be exceeded and the spring load will be reduced. Also, while the electrical circuit is formed in parallel while both contacts are in contact, the current mainly flows through the electrical circuit formed by both contacts, so even if the coil spring exceeds the transformation point temperature, it will return to its original state. Accordingly, the spring load also returns to its original state, so that the opening operation operates in the same manner as in the previous embodiment.

[Effects of the Invention] The contact structure of the switchgear according to the present invention has one end joined to the base and the middle part joined to the movable contact, and the movable contact is attached with a spring so as to resist the driving force of the electromagnetic drive member. In addition, a coil spring is provided whose other end faces the fixed contact, and the coil spring can be fixed or fixed.When the fixed contacts are in contact, an electric circuit is formed in parallel with this, and the coil spring is connected to the fixed contact. f&
At the time of contact operation during separation operation, an electric path is formed in advance,
Since it is designed to disconnect the electric circuit with a delay during the disconnection operation, it suppresses the rush current during the connection and disconnection operation and lowers the Joule heat at the contact part compared to conventional ones.
In addition, bounce can be reduced, arc generation is reduced, damage to contacts is reduced, and the resistance to welding of contacts against rush currents is improved.In addition, the coil spring also serves as a return spring for the electromagnetic drive member, making it possible to reduce damage to contacts. This eliminates the need for a dedicated return spring.

[Brief explanation of drawings]

Figures 1 to 6 show one embodiment of the present invention, with Figure 1 being a sectional view of one used in a hinge type relay, and Figure 2 (
a) to (e) are side views of main parts explaining the operation, Figure 3 is a current one hour curve diagram, Figure 4 is a load-stroke curve diagram,
Fig. 5 is a contact pressure one-hour curve diagram, Fig. 6 (a) is an arc current one-hour curve diagram, (b) is an arc voltage one-hour curve diagram, and Fig. 7 is a load diagram of another embodiment of the present invention. It is a stroke curve diagram. 2--device stand, 3--fixed contact, 4--fixed contact, 7-
-・Movable contact, 8-movable contact, 15-coil spring, D
-・-Drive member. Patent applicant Matsushita Electric Works Co., Ltd. Patent attorney Toshikuro Takemitsu (and 2 others) Figure 1 Figure 3 Figure 5 Figure 6

Claims (1)

[Claims] (1) Contact part of a switchgear consisting of a fixed contact that has a fixed contact and is fixed on the device stand, and a movable contact that has a movable contact that makes contact with and separates from the fixed contact and is driven by an electromagnetic drive member. In the structure, one end is joined to the device stand and an intermediate part is joined to the movable contact, the movable contact is biased by a spring so as to resist the driving force of the electromagnetic drive member, and the other end is connected to the fixed contact. A coil spring facing each other is provided, and the coil spring forms an electric path in parallel with the two contacts when they are in contact with each other, and forms an electric path in advance of the contact operation when the two contacts are connected and separated. A contact structure of a switchgear that disconnects the electrical circuit with a delay during operation.