JP3012831B2 - Vacuum valve heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device for a vacuum valve, and more particularly, to a device for heating a PTC thermistor having a positive temperature coefficient outside or inside a vacuum valve.
The present invention relates to a novel improvement having both heating and temperature control functions and achieving gentle heating temperature change and line saving.

[0002]

2. Description of the Related Art Conventionally, a heating device for a vacuum valve of this type has been used as disclosed in Japanese Patent Application Laid-Open Nos. 8-13149 and 7-198063. A heater such as a sheath heater, a tape heater, and a jacket heater is installed, and the inside of the valve box is provided with a heating method by heat conduction from those external heaters and a heater for actively heating the valve plate and the bellows portion, A method of performing temperature control by a temperature control device has been adopted. Further, a combined heating method of heating the inside and the outside of the valve box, respectively, has also been adopted.

[0003]

Since the conventional vacuum valve heating device is configured as described above, there are the following problems. (1). In the method using only heating from the outside of the valve, a large difference occurs between the outside temperature and the inside temperature. It is necessary to keep it, which is extremely uneconomical. (2). The conventional method of heating the inside of a valve requires wiring of a temperature sensor such as a thermocouple and a heater, and it is complicated to introduce the inside of the valve. In addition, there are problems such as the life of the heater itself, early disconnection due to local overheating, and reliability of the temperature sensor (including appropriate detection position). (3). Generally, in heating and keeping these valves, the heater capacity required for obtaining the heating rate and the heater capacity required from the heat balance are larger in the former, so it is difficult to maintain the constant temperature without some kind of temperature control. is there. The temperature control method is selected according to the allowable value of the temperature, but in any case, a temperature detection circuit and a circuit for controlling the power of the heater are required.

[0004] The present invention has been made to solve the above problems, and in particular, a PT having a positive temperature coefficient.
By using the C thermistor for heating either inside or outside the vacuum valve, it has functions of both heating and temperature control, and heats the vacuum valve so as to achieve gentle heating temperature change and line saving. It is intended to provide a device.

[0005]

According to the present invention, there is provided a vacuum valve heating apparatus comprising: a valve box having an air inlet and an air outlet arranged in an L shape; a first heater formed on the outer periphery of the valve box; In a vacuum valve heating device for heating the valve box and the valve body using a valve body for opening and closing an outlet and a second heater for heating the valve body, any one of the first and second heaters The first heater is a PTC thermistor having a positive temperature coefficient, and the first heater is a pair of first and second series-connected heaters.
A second heater section, wherein the second heater is formed of the PTC thermistor and connected in parallel with the first heater section, wherein the first and second heaters form a parallel series circuit; The first heater and the second heater are configured by a series circuit connected in series.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIGS. 1 and 2 show a vacuum valve heating device according to the present invention. A device denoted by reference numeral 1 is an L-shaped valve box in which an air inlet 2 and an air outlet 3 are arranged. The outer periphery of the first unit 1 is composed of a conventional general-purpose heater such as a rubber heater and a sheath heater.
A heater 4 is provided.

An air cylinder 5 is provided on a top plate 1A above the valve box 1. A disc-shaped valve plate 8 is provided below a piston rod 7 provided on a piston 6 of the air cylinder 5. The sealing surface 8 a having the O-ring 9 of the valve plate 8 is provided so that the air outlet 3 can be sealed. Between the top plate 1A and the valve plate 8, an expandable and contractible ring-shaped bellows 10 is provided.
The bellows 10 separates the air cylinder 5 side on the atmosphere side and the vacuum side of the valve box 1 from each other at the outer peripheral position of the bellows.

A second heater 12 is provided on the outer periphery of a holding body 11 provided in a ring shape from the valve plate 8 along the outer periphery of the piston rod 7, and a lead wire for supplying power to the second heater 12 is provided. Reference numeral 13 is led out of the valve box 1 via the outer periphery of the shaft portion 1B of the top plate 1A. Therefore, as the lead wires connected between the power supply 20 side and the vacuum valve 21 shown in FIG. 3, there are only two lead wires 14 connected to the first heater 4 in addition to the lead wire 13. Further, by selectively supplying and discharging air from the first valve 5A and the second valve 5B of the air cylinder 5, the valve plate 9 is axially moved via the piston 6 and the piston rod 7, and the air outlet 3 is provided. The opening / closing valve operation can be performed.

The second heater 12 is made of a well-known PTC thermistor (positive temperature co-efficient thermistor) having a positive temperature coefficient, and is made of an oxide semiconductor ceramic containing barium titanate as a main component. . As shown in FIG. 5, the PTC thermistor has a property that the electric resistance increases sharply from a certain temperature (Curie temperature), and has a heating action by Joule heat until the Curie temperature is reached. It has an action as a heater. When the temperature exceeds the Curie temperature, the resistance value sharply increases, and the current starts to decrease. Therefore, a self-temperature control operation is provided without using a control circuit or the like.

The first heater 4 and the second heater 12 are
As shown in FIG. 4, the first heater 4 includes a pair of first and second heater sections 4a and 4b connected in series, and the second heater 12 is connected in parallel to the first heater section. As shown in FIG. 6, the total resistance R is R = (R2R3 / R2 + R3) + R1, so that when R2６R3, R ≒ R3 + R1, and the Curie temperature is reached. Thereafter, the outside and inside of the vacuum valve 21 undergo a gentle temperature change.

[0011] The configuration shown in FIG.
The heaters 4 and 12 are composed of a series circuit in which the heaters 4 and 12 are connected in series. The total resistance R is R = R1 + R2, and R 時 に R2 when R2≫R1. In the above-described embodiment, the case where the second heater 12 is a PTC thermistor has been described. However, similar effects can be obtained when the first heater 4 is a PTC thermistor and the second heater is a conventional sheathed heater or the like. . In addition to the above-described embodiment, both the first and second heaters 4 and 12 may be the PTC thermistors.

[0012]

The heating device for a vacuum valve according to the present invention
With the above configuration, the following effects can be obtained. That is, since either the outside or inside (valve plate side) heater of the vacuum valve is constituted by the PTC thermistor, the positive temperature characteristic of the PTC thermistor automatically makes it possible without using a conventional heater control device. Temperature control can be performed, the number of wires connected from the outside to the inside can be reduced, and wire saving can be achieved.
Also, the power supply is turned on / off only by the temperature characteristics of the PTC thermistor.
Performs the same function as off, so
A switching contact or the like for turning off is not required, and the above-described line saving and reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a vacuum valve heating device according to the present invention.

FIG. 2 is an external view of FIG.

FIG. 3 is a configuration diagram showing a state in which a power supply is connected to the vacuum valve of FIG. 1;

FIG. 4 is a parallel series circuit diagram of each heater of FIG. 1;

FIG. 5 is a temperature-resistance characteristic diagram of the PTC thermistor of FIG. 1;

FIG. 6 shows a temperature of a parallel series circuit of the PTC thermistor of FIG. 1;
FIG. 4 is a resistance characteristic diagram.

FIG. 7 is a series circuit diagram showing another embodiment of FIG. 4;

FIG. 8 is a temperature-resistance characteristic diagram of the series circuit of FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Valve box 2 Air inlet 3 Air outlet 4 First heater 8 Valve body 12 Second heater 4a, 4b First and second heater parts

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16K 49/00-51/02

Claims (2)

(57) [Claims] 1. A valve box (1) having an air inlet (2) and an air outlet (3) arranged in an L-shape, a first heater (4) formed on the outer periphery of the valve box (1), Valve (8) for opening and closing the air outlet (3)
And a vacuum valve heating device for heating the valve box (1) and the valve element (8) using a second heater (12) for heating the valve element (8), Either of the two heaters (4, 12) has a positive temperature coefficient and the first heater (4)
Is composed of a pair of first and second heater sections (4a, 4b) connected in series, and the second heater (12) is composed of the PTC thermistor and connected in parallel with the first heater section (4a). The first and second heaters (4, 12) constitute a parallel series circuit, wherein the heating device is a vacuum valve. 2. A valve box (1) having an air inlet (2) and an air outlet (3) arranged in an L-shape, a first heater (4) formed on the outer periphery of the valve box (1), Valve (8) for opening and closing the air outlet (3)
And a vacuum valve heating device for heating the valve box (1) and the valve element (8) using a second heater (12) for heating the valve element (8), Either of the two heaters (4, 12) has a positive temperature coefficient and the first heater (4)
And a second heater (12) comprising a series circuit connected in series.