JPS6178016A - Sealed type contact unit - 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 sealed contact device applicable to power load switching devices such as electromagnetic switches and relays.

(Background technology) Generally speaking, switching equipment has an IA
Switching equipment for the following weak currents (commonly known as dry circuits),
Switching equipment for resistive load control of about 1 to 5 A, 5 to 30
It is classified into switching equipment for power loads of A level (small capacity inductive loads, etc.) and switching equipment for medium to large capacity loads or specific loads of 3OA or more. Among these, power load switching equipment, which is most in demand, has electrical lifespans of 100,000 to 100,000 cycles due to arcing during switching, which accelerates contact welding and contact wear.
The current situation is that it can only be obtained about 0,000 times. However, customers are demanding a maintenance-free electrical life of more than 1 million cycles.

In order to meet this demand, various studies have been conducted on contact materials, high-speed contact opening drive mechanisms, etc., but no proposal has yet been made that satisfies consumers.

In addition, there is a Mercury relay that uses a sealed contact device, which has improved arc resistance (arc extinguishing ability) from a different perspective than the contact material and high-speed contact opening drive mechanism. In other words, the contact stability is improved by wetting the contacts with mercury supplied by capillary action, and the arc extinguishing ability is enhanced by utilizing the cooling power of high-purity hydrogen gas sealed at 17 to 20 atmospheres. . When the switching current exceeds 58, the amount of evaporation of mercury increases when the contacts open and close, making it impossible to supply sufficient mercury to the contacts, resulting in contact wear and contact welding, which shortens the electrical lifespan. As a result, it has been difficult to put this into practical use in power load switching equipment with a current cutoff range of approximately 5 to 30 A.

[Object of the Invention] The present invention has been made in view of the above points, and its purpose is to improve the arc extinguishing ability and extremely reduce the current/arc time product that determines the amount of contact wear. An object of the present invention is to provide a sealed contact device that can significantly improve electrical life.

[Disclosure of the Invention] The sealed contact device according to the present invention improves the arc extinguishing ability by sealing hydrogen gas mixed with nitrogen at at least 1 atmosphere in a sealed container, thereby increasing the current flow rate and determining the amount of contact wear. The arc time product can be made extremely small, thereby significantly improving the electrical life.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

Reference numeral 1 denotes a sealed container, which is composed of a case 2 formed of glass or ceramic in the shape of a cylinder with a bottom, and a diaphragm 3 that closes the opening of the case 2.

A fixed electrode 4 is provided with a fixed contact 5 and is fixedly fixed through the bottom part 2a of the case 2 in a sealed manner, and a fixed electrode 6 is provided with a movable contact 7 that connects and separates from the fixed contact 5 and is fixedly fixed through the center of the diaphragm 3 in a sealed manner. Both electrodes 4.6 are made of acid-free copper or deoxidized copper and are formed into a rod shape and arranged coaxially.

8 is an arc horn provided on both electrodes 4 and 6 so as to be close to each contact 5 and 7 and to face each other, and has approximately the same width as both contacts 5 and 7, and is bent so that both sides are slightly open. facing each other. Reference numeral 9 denotes a magnetic driving means for transferring and enlarging the arc generated between the two contacts 5 and 7 between the arc horns 8, and is composed of a U-shaped yoke 10 and a permanent magnet 1). That is, in the yoke 10, the opposing piece 10a has an opposing interval that is sufficiently larger than the diameter of both contacts 5.7, and both contacts 5.7
The connecting piece 4b is fixed to the bottom 2a of the case 2 so as to sandwich the arc horn 8 therebetween.

Furthermore, permanent magnets 1) are joined to the inner surfaces of the tips of both opposing pieces a, which are close to and face each other from both contacts 5.7. This permanent magnet 1) has north poles and south poles magnetized in opposite directions.

12 is an arc-circuit prevention insulating plate made of ceramic/reinforced material;
It is disposed between both contacts 5.7, the arc horn 8, and the magnetic drive means 9, and prevents tM scratches on the permanent magnet 1) due to the arc and arc shorting via the magnetic drive means 9.

Reference numeral 13 denotes an electromagnet device which is a driving means for the movable electrode, and includes a coil 14, a fixed core 15 having an attraction surface 15a and fixed to one side of the inner circumference of the coil 14, and Attracted surfaces 16a facing each other with a predetermined gap therebetween
and a direction in which the movable core 16 is supported on the inner periphery of the coil 14 so as to be movable in the axial direction and has a driving portion 16b extending to the opposite side of the attracted surface 16a, and a direction in which the movable core 16 is separated from the fixed core 15. The return spring 17 is compressed and elastically loaded between the attracted surface 16a of the movable core 16 and the attracted surface 15a of the fixed core 15 to bias the spring.

Reference numeral 18 denotes a drive lever, the middle part of which is pivotally supported by a shaft 19, and the other end 18b of which is connected to the drive part 16b of the electromagnet device 13 at one end 18a.
are connected to the movable electrodes 6, respectively.

Next, to explain the main part of the present invention in detail, N2 (nitrogen) is preferably mixed with O to 40% in the sealed container l.
2 (hydrogen gas) is sealed at a pressure of 1 to 100 atmospheres.

Generally, in order to increase the arc extinguishing ability, the contact opening operation is made high speed, the arc is transferred to the arc horn by a magnetic drive means, and the arc is stretched by the arc horn to obtain a high arc voltage.

In other words, if the arc moves at high speed, the amount of arc elongation will inevitably increase and a high arc voltage will be obtained. Therefore, we focused on the atmosphere in which the arc exists, and conducted experiments to find an atmosphere in which the arc can move at high speed, that is, a gas.

FIG. 2 is a curve showing the relationship between gas thermal conductivity and arc transition time. This thermal conductivity (horizontal axis) is A (argon)
This was achieved by changing the mixing ratio of He (helium) and
If A is 50.25.0% at 0°C, its thermal conductivity is 20.6, 32.8, 58.4x to
-'[L'cm"・see ].The arc transition time (vertical axis) is as follows: The contact current is 3 kApeak, the contact opening time is 0.94 m5ec, and the 2 mm displacement time is 0.43.
The time in the case of m5ec is shown as [m5ec]. According to the results of this experiment, it can be seen that as the thermal conductivity of the gas increases, the arc transition time decreases, that is, the arc transition can be performed at high speed.

It is also known that hydrogen gas has the highest thermal conductivity among existing gases (especially at high temperatures where an arc exists), and therefore it is possible to generate an arc in hydrogen gas. If so, the cooling force for the arc will be extremely strong.Furthermore, the electric field of the arc positive column of various gases at 1 atm X [V/cm] and the current 1 [A]
It is also known that the relationship is as shown in FIG. That is, hydrogen gas has an electric field of X [V/c
+n], ie the arc voltage is the largest, and in addition it is proportional to the gas pressure. In the figure, R is the radius of the tube in which the arc positive column exists, and R=2 cm.

From this, it was found that hydrogen gas is optimal for arc transfer, but on the other hand, hydrogen gas has a low dielectric strength voltage, so if an arc is generated in hydrogen gas, the generated arc will be The voltage causes a so-called arc short phenomenon.

Therefore, by mixing nitrogen, preferably 0 to 40%, with hydrogen gas as described above, the dielectric strength voltage can be increased to a value close to that of nitrogen without impairing the original arc cooling power of hydrogen gas. A high arc voltage can be stably generated.

To explain the operation of this contact device, FIG. 1 shows that the coil 14 of the electromagnet device 13 is excited, and the movable iron core 16 is attracted in the direction of arrow A against the spring force of the diaphragm 3 and return spring 17. The movable electrode 6 is in a contact open state that has moved in the direction of arrow B. When the coil 14 of the electromagnet device 13 is demagnetized in this state, the movable iron core 16 and the movable electrode 6 are moved back in the opposite direction to the above-mentioned direction by the spring force of the diaphragm 3 and the return spring 17, and are brought into contact state.

During this contact/separation operation, an arc is generated between the contacts 5 and 7, but the arc moves onto the arc horn 8 due to the magnetic force of the permanent magnet 1) facing each other with the contacts 5 and 7 in between and the arc current. It is stretched and powerfully cooled by the mixed hydrogen gas G, and the high voltage required for current limiting is instantaneously generated, making the current/arc time product, which determines the amount of contact wear, extremely small.

FIG. 4 is a curve showing the relationship between the applied current and the arc transition time, which was obtained through experiments using various materials for the contact, focusing on contact materials in order to enable faster arc transition. We beam (tungsten), Cu (copper), N
i Soquel), Ag (silver).

For each Pb (lead) material, the current (horizontal axis) is 1°2.
5, 1.5.1.75.2.25 [kApeak]
Each arc transition time (vertical axis) [m5
ec] was measured. According to this, the melting point of W is much higher.
It can be seen that the arc transition time at (3410° C.) is extremely short, that is, the arc transition can be performed at high speed. Therefore, if hydrogen gas G mixed with nitrogen is sealed in the sealed container 1 and the contact material is made of a high melting point material such as -,
This allows the arc to move even faster.

In the embodiment, an electromagnet device is used as a means for driving the movable electrode, but it is needless to say that the present invention is not limited to this.

Similarly, the sealed container is not limited to one using a diaphragm.

[Effects of the Invention] In the sealed contact device according to the present invention, hydrogen gas mixed with nitrogen is sealed in a sealed container at a pressure of at least 1 atmosphere.
This has the effect of increasing the arc extinguishing ability and extremely reducing the current/arc time product that determines the amount of contact wear, thereby significantly improving the electrical life.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing an embodiment of the present invention, Figure 2 is a characteristic diagram showing the relationship between thermal conductivity and arc travel time, and Figure 3 is a diagram showing the relationship between electric field and current in the arc positive column of various gases. Characteristic diagram,
FIG. 4 is a characteristic diagram showing the relationship between current flowing through various contacts and arc transition time. DESCRIPTION OF SYMBOLS 1- Sealed container, 2... Case, 3... Diaphragm, 4... Fixed electrode, 5... Fixed contact, 6- Movable electrode, 7... Movable contact, 8-... Arc horn, 9 --Magnetic drive means, 13...-Electromagnetic device, 18-Drive lever, G-Mixed hydrogen gas. Patent applicant: Matsushita Electric Works Co., Ltd. Patent attorney Toshimaru Takemitsu (2 fools) Figure 1 Figure 3 Figure 1 (A) Figure 4 Current flow (to KAptA).

Claims (1)

[Claims] (1) A fixed electrode provided with a fixed contact, a movable electrode provided with a movable contact that contacts and separates from the fixed contact and driven by a driving means, and a movable electrode provided on both electrodes so as to be close to each contact and face each other. In a sealed contact device, which has an arc horn and a magnetic drive means for transferring and stretching the arc generated between the two contacts, and these are arranged in a sealed container, nitrogen is mixed. A sealed contact device characterized in that hydrogen gas is brought to a pressure of at least 1 atmosphere and is sealed in the sealed container.