JPH04206410A - Sealed contact device - Google Patents

Abstract

PURPOSE:To prevent production of cracks in heat-resistant members or deterioration of a gas sealability or insulation of a sealed container by providing heat- resistant members of ceramic having a thermal expansion ratio of less than about 1.5X10<-6>/ deg.C and a heat impact resistance of more than about 900 deg.C on the inner surface of the sealed container. CONSTITUTION:Heat-resistant members 1f, 1g, 1h of ceramic having a thermal expansion ratio of less than about 1.5X10<-6>/ deg.C, and a heat impact resistance of more than about 900 deg.C are provided on the inner surface of a sealed container 1 enclosing a fixed contact 2a and a movable contact 3a. A load condition to be switched by a contact can thus be increased to set a ratio L/R for an induced load L and a resistance load R to be as large as 40ms, and even in the case a continuous period of an arc A in dissociation of the contacts becomes very long, production of cracks at the heat-resistant members due to a heat impact added by motion of the arc A toward a trunk part 1a of the sealed container 1 b a Lorentz's force based on a magnetic field B of a pair of permanent magnets 1i can be eliminated, and troubles such as deterioration of a gas sealability or insulation of the sealed container 1 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sealed contact device suitable for power load relays, value switches, etc.

(Prior Art) There are conventional sealed contact devices with the following structure, which will be explained based on FIG. 4 and Part 5.

Reference numeral 11 denotes a sealed container, which has a body 11a formed of alumina, which is a type of ceramic, into a substantially rectangular cylindrical shape, and a flat upper end formed of a metal material and fixed by closing both ends of the body 11a. It has a box-like structure consisting of a plate 11b and a U-shaped lower end plate 11c, and an electrically insulating gas such as hydrogen gas is hermetically sealed at high pressure inside. In this sealed container 11, in order to increase the insulation distance between the fixed electrode 12 and the movable electrode 13, which will be described later, an insulating plate 11d made of alumina and an insulating plate are provided to cover the upper end plate 11b and the lower end plate 11c. A member lie is arranged respectively. Further, a pair of permanent magnets 11f are sandwiched between the outer wall of the body portion 11a and the opposing piece of the U-shaped lower end plate 11c to generate a magnetic field B.

Reference numeral 12 denotes a fixed electrode, and a fixed contact 12a is fixed to the tip.

Reference numeral 13 denotes a movable electrode, which has a movable contact 13a fixed to one end thereof, which is driven in the axial direction to move toward and away from the fixed contact 12a in the axial direction within the sealed container 11, and a return spring 13b. is installed.

Reference numeral 14 denotes a cylindrical portion made of a metal material in a cylindrical shape, and one end of which is hermetically connected to the upper end plate 11b of the sealed container 11 so that the movable electrode 13 can be inserted therethrough.

Reference numeral 15 denotes a bellows, which is made of a thin metal material and has a bellows shape, and is hermetically fixed to the movable electrode 13 at one end and to the cylindrical portion 14 at the other end.

The operation of this sealed contact device is such that when the movable electrode 13 is driven in the axial direction by the pressing force of a driving means (not shown), the movable contact 13a provided at one end of the movable contact 13a opens to the fixed contact 12a and becomes conductive. , when the pressing force is removed, the movable electrode 13 returns to its original position due to the return force based on the return spring 13b and the pressure difference between the inside and outside of the sealed container 11, and the movable contact 13a returns to the fixed contact 12a.
Separate from. The bellows 15 expands and contracts in response to the movement of the movable electrode 13. Then, as shown in FIG. 4, two arcs A are generated when the magnets are separated, and the arc A is caused by the Lorentz force based on the magnetic field B of the pair of permanent magnets IH to move the sealed container 11.
The arc is extinguished by the blowing action of the contact point moving toward the body 11a side and the cooling ability of the electrically insulating gas sealed in the sealed container 11, thereby extending the life of the contact and improving reliability.

[Problems to be Solved by the Invention] In the conventional sealed contact device described above, the conditions for the load to be opened and closed by the contact are made stricter, for example, the ratio L/R of the inductive load to the resistive load R is set to 40m5. When opening and closing a DC load increased to Due to thermal shock, a crank occurs in the alumina body 11a, the insulating plate lid, etc. that surround the fixed contact 12a and the movable contact 13a and form the inner surface of the sealed container 11, and the airtightness of the sealed container 11 deteriorates. Problems such as damage to the insulation or deterioration of insulation may occur.

The present invention was made in view of the above reasons, and its purpose is to prevent the airtightness of a sealed container by the arc generated when the contacts are opened when switching a DC load with an L/R of 40 m5 or less. An object of the present invention is to provide a sealed contact device in which insulation properties are not impaired.

Means for Solving Problem C] In order to solve the above-mentioned problems, the sealed contact device of the present invention includes a sealed container in which an electrically insulating gas is sealed to form an airtight space, and a tip of the sealed contact device. A fixed electrode with a fixed contact,
A movable electrode that is driven in the axial direction and has a movable contact at one end that contacts and separates from the fixed contact in the axial direction within the sealed container, a cylindrical portion through which the movable electrode is inserted, one end of which is the movable electrode, and the other end of which is provided. A sealed contact device having bellows each fixed to a cylindrical part, wherein an inner surface of the sealed container surrounding the fixed contact and the movable contact has a coefficient of thermal expansion of approximately 1.5 xl.
The structure is such that a ceramic heat-resistant member having a thermal shock resistance of approximately 900° C. or higher at a temperature of O-'/''c or less is provided.

[Effect]

In the sealed contact device according to the present invention, the inner surface of the sealed container surrounding the fixed contact and the movable contact has a coefficient of thermal expansion of approximately 1.5×1.
Since we have installed a ceramic heat-resistant member with a thermal shock resistance of approximately 900'C or more at temperatures below 0-6/'C, the load condition for switching at the contact point is the ratio of inductive load to resistive load R. Even if the radius R is increased to 40 m5 and the duration of the arc at the time of contact opening becomes very long, cracks will not occur in the heat-resistant member due to thermal shock at that time.

〔Example〕

An embodiment of the present invention will be described below based on FIGS. 1 to 3.

Reference numeral 1 denotes a sealed container, which includes a body 1a made of alumina, which is a type of ceramic, and formed into a substantially rectangular cylindrical shape, and a flat plate made of a metal material and fixed by closing both ends of the body 1a by brazing. It has a box-like structure with a U-shaped upper end plate 1b and a U-shaped lower end plate 1c, and is electrically insulating for hydrogen gas etc. After gas is sealed in at high pressure, the trachea 1e is crimped to form an airtight space.

Inside this sealed container l, in order to increase the insulation distance between a fixed electrode 2 and a movable electrode 3, which will be described later, a structure is provided to cover the inner surfaces of an upper end plate 1b and a lower end plate 1c formed of a metal material. An insulating plate 1r and an insulating member 1g are respectively disposed, and are formed into a square cylindrical shape with a thickness of about IIIM so as to cover the inner surface of the body 1a located between the insulating plate 1f and the insulating member 1g. A covering body member 1h is provided. That is, the inner surface of the sealed container 1 that surrounds the fixed contact 2a and the movable contact 3a, which will be described later, consists of an insulating plate 1f and an insulating member 1.
It is covered in a box shape by g and the covering member 1h. Incidentally, although the insulating plate 1f and the insulating member 1g were included in the conventional example, the covering member 1h is newly provided. However, although the details of these members will be described later, they are made of aluminum titanate, which is also a type of ceramic that has better heat resistance than alumina.

A pair of permanent magnets 11 are sandwiched between the outer wall of the body portion 1a and the opposing piece of the U-shaped lower end plate IC to generate a magnetic field B.

Reference numeral 2 denotes a fixed electrode, which is formed into a cylindrical shape from a metal material such as acid-free copper, has a fixed contact 2a made of di-tungsten-based material fixed at the tip, and has its base end fixed to the lower end plate IC of the sealed container l. and the insulating member 1g is provided around it.

Reference numeral 3 denotes a movable electrode, which is formed into a rod shape from a metal material such as acid-free copper, and has a movable contact 3 made of a tungsten-based material at one end.
a is fixed. It is guided by a bearing 3b so as to be driven in the axial direction, and a coiled return spring 3c is disposed above the bearing 3b.

Reference numeral 4 denotes a cylindrical portion, which is formed into a cylindrical shape from a metal material, and one end of which is connected to the upper end plate 1b of the sealed container 1 so that the movable electrode 3 can be inserted therethrough.
are hermetically coupled.

A bellows 5 is formed into a bellows shape by adding corrugated pleats to a thin metal cylinder. One end is hermetically fixed to the movable electrode 3 near the upper end plate 1b, and the other end is secured to the cylindrical portion 4 by a bellows retainer 5a. It is hermetically fixed at the top end. Therefore, the airtight space of the sealed container 1 described above is constructed together with the above-mentioned members to maintain airtightness.

The operation of this sealed contact device is such that when the movable electrode 3 is driven in the axial direction by the pressing force of a driving means (not shown), the movable contact 3a provided at one end of the movable contact 3a closes to the fixed contact 2a and becomes conductive. ,
Further, when the pressing force is removed, the movable electrode 3 returns to its original position due to the return force based on the return spring 3c and the pressure difference between the inside and outside of the sealed container 1, and the movable contact 3a separates from the fixed contact 2a. The bellows 5 expands and contracts in response to the movement of the movable electrode 3. As shown in FIG. 1, the arc A generated at the time of opening is caused by the blowing effect of moving toward the body 1a of the sealed container 1 due to the Lorentz force based on the magnetic field B of the pair of permanent magnets 11, and The arc is extinguished by the cooling ability of the electrically insulating gas sealed inside, thereby increasing the longevity and reliability of the contacts.

Here, the materials of the insulating plate 1f, the insulating member 1g, and the covering member 1h that cover the inner surface of the sealed container 1 in a box shape will be explained in detail.

Figure 3 is a diagram showing the relationship between the coefficient of thermal expansion and thermal shock resistance (temperature difference in thermal shock) of various ceramics, which are heat-resistant materials. This point shows that cracks will not occur if the thermal expansion coefficient is less than or equal to the thermal shock resistance shown by the joint shaft. Among these points, for example, point a is alumina, point b is aluminum titanate, point C is carbon, point d is poron nitride,
are shown respectively.

On the other hand, according to the inventor's experiments, one side made of each of the above-mentioned ceramics has a thickness of about 10 to 151 mm, and a thickness of III
A box-shaped case of about l size is used as an insulating plate if! ! When load switching was actually performed using a test product that was arranged to cover the inner surface of the sealed container 1 instead of the edge member 1g and the covering member 1h,
When the ratio L/R of the inductive load to the resistive load R is 4011s, cracks due to the thermal shock of the arc A that occur when the contacts open are caused by aluminum titanate at point b and aluminum titanate at point C shown in Figure 3. Although it did not occur in the box-shaped cases made of carbon and boron nitride at point d, it was confirmed to occur in other cases. Therefore, the diagonal line area including the three points b, c, and d, that is, the coefficient of thermal expansion is approximately 1.5 × 10-”/
If the insulating plate 1f, the insulating member 1g, and the covering member 1h are made of ceramic having a thermal shock resistance of approximately 900'C or more at temperatures below As a result, cranking will not occur. Since the alumina at point a used in the conventional example does not belong to the above range, in this embodiment, each of the heat-resistant members described above is formed using aluminum titanate at point b instead.

In such a sealed contact device, the coefficient of thermal expansion is approximately 1.5.
Thermal shock resistance is approximately 900'C below ×10-6/'C
By using aluminum titanate, which is a ceramic having the above values, the heat-resistant member consisting of the insulating plate 1f, the insulating member 1g, and the covering member 1h covers the inner surface of the sealed container l surrounding the fixed contact 2a and the movable contact 3a. Since it is arranged in a box-shaped manner, the load conditions for opening and closing the contacts are such that the ratio L/R of the inductive load and the resistive load R is increased to 40m5, and the duration of the arc when the contacts open is very short. Even if the arc A becomes long, the arc A moves to the body part 1a (!]!I of the sealed container 1 due to the heat shock caused by the magnetic field B of the pair of permanent magnets 11, and the heat-resistant member There will be no cracks, and problems such as loss of airtightness of the f:1 container 1 and deterioration of insulation properties will not occur.

In this embodiment, the cover body member 1h made of aluminum titanate is used as the heat-resistant member, but if it is possible to airtightly fix it to the upper end plate 1b and lower end plate 1c formed of metal material by brazing. Alternatively, instead of the covering body member 1h, the body portion 1a of the sealed container 1 itself may be formed of aluminum titanate to constitute a heat-resistant member.

〔Effect of the invention〕

In the sealed contact device of the present invention, the inner surface of the sealed container surrounding the fixed contact and the movable contact has a coefficient of thermal expansion of approximately 1.

Thermal shock resistance is approximately 900℃ below 5 ×10-6/'C
Since we installed a ceramic heat-resistant member with the above value, the load condition for opening and closing at the contact is to increase the ratio L/R of inductive load and resistive load R to 40tgs, and the duration of the arc when the contact opens. Even if the heat-resistant member becomes extremely long, the thermal shock at that time will not cause the heat-resistant member to crack, and problems such as loss of airtightness of the sealed container and deterioration of insulation properties will not occur.

[Brief explanation of the drawing]

Fig. 1 is a front sectional view showing one embodiment of the present invention, Fig. 2 is a side sectional view of the same, and Fig. 3 is a diagram showing the relationship between the coefficient of thermal expansion and thermal shock resistance of various ceramics. , FIG. 4 is a front sectional view showing a conventional example, and FIG. 5 is a side sectional view of the same. 1-Sealed container, 1f--insulating plate, Ig--insulating member, 1h--covering member, (the above 1f, 1g, and 1h are heat-resistant members) 2-
・-Fixed electrode, 2a...-Fixed contact, 3--Movable electrode, 3a--Movable contact, 4-Cylinder part, 5-Heroze.

Claims (1)

[Claims] (1) A sealed container in which an electrically insulating gas is sealed to form an airtight space, a fixed electrode with a fixed contact at the tip, and a fixed electrode that is driven in the axial direction and inside the sealed container in the axial direction. A sealed contact device comprising: a movable electrode provided at one end with a movable contact that contacts and separates from a fixed contact; a cylindrical portion through which the movable electrode is inserted; and a bellows having one end fixed to the movable electrode and the other end fixed to the cylindrical portion. In, the inner surface of the sealed container surrounding the fixed contact and the movable contact has a coefficient of thermal expansion of approximately 1.5×10^-^6/℃ or less and a thermal shock resistance of approximately 900℃ or higher. A sealed contact device characterized by disposing a ceramic heat-resistant member.