JPH10284347A - Vacuum variable capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase current carrying capability, by arranging a cylindrical bellows which is concentrically arranged around a first bellows, in such a manner that one end is fixed to a movable side current collecting member, the other end is fixed to a movable side fixing conductor or a movable lead, and the diameter is larger than that of the first bellows. SOLUTION: In a vacuum variable capacitor, a cylindrical second bellows 17 is concentrically arranged around a first bellows 16. The one end of the bellows 17 is hermetically fixed to a movable side current collecting member 4, and the other end is hermetically fixed to a movable side fixing conductor 6. In the above structure, the diameter of the second bellows 17 is made larger than that of the first bellows 16. Vacuum in a vacuum vessel 1 is doubly performed with the first and the second bellowses 16, 17. The second bellows 17 is formed by coating copper or silver or stainless steel with copper or by coating stainless steel with silver.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum variable capacitor used for an oscillation circuit of a high-power transmitter, a high-frequency power supply circuit for a semiconductor manufacturing device, a tank circuit of an induction heating device, and the like.

[0002]

2. Description of the Related Art There has been proposed in Japanese Patent Application No. 6-233912 by the present applicant for stabilizing the withstand voltage and capacitance characteristics of a vacuum variable capacitor and reducing the overall length. This will be described with reference to FIGS. In FIG. 1, reference numeral 1 denotes a cylindrical vacuum vessel having an evacuated interior, and is formed by tightly attaching a fixed-side mounting conductor 3 and a movable-side current collector 4 to both ends of a cylindrical portion 2. Also, cylindrical part 2
Are formed by joining copper cylinders 2b and 2c to both ends of an insulating cylinder 2a made of ceramic or the like. On the inner surface side of the fixed-side mounting conductor 3, a plurality of cylindrical electrode plates F ₁ ,
F _2, ... and forms a fixed electrode 5 mounted with a predetermined interval concentrically, and a plurality of cylindrical electrode plates diameter to be inserted and out are different in a non-contact to each electrode plates of the fixed electrode 5 M
_1, M _2, to form a movable electrode 7 ... to the movable side mounting conductor 6 is attached concentrically.

[0003] Reference numeral 8 denotes a guide pin erected at the center of the inside of the fixed-side mounting conductor 3, that is, at the axis of the fixed electrode 5. The guide 9 is provided with a fitting hole 9a that slidably fits with the guide pin 8. An insertion hole 4a is provided at the center of the movable-side current collector 4, and one end of a cylindrical screw receiving portion 10 is attached to the inner surface of the movable-side current collector 4 at a peripheral portion of the insertion hole 4a. The other end of the screw receiving portion 10 is provided with a flange portion 10a. 11 is a screw receiving part 1
1a, one end of which is fitted into a fitting hole 1 of a movable lead 12 formed integrally with the guide portion 9.
The screw portion 11a is inserted and fixed to the flange portion 10a of the screw receiving portion 10. The fitting holes 9a and 12a are continuously formed to have the same diameter. Reference numeral 13 denotes an adjustment nut having a screw hole 13a.
Is screwed into the screw hole 13a in the screw receiving portion 10.
One end of the adjusting nut 13 is connected to the flange 10 via a bearing 14.
a is rotatably supported on the outer surface side.

A screw hole 11b is provided at the tip of the movable lead bolt 11, and an adjusting screw 15 is screwed into the screw hole 11b. The adjusting nut 13 is provided with a large-diameter hole 13b having a larger diameter than the screw hole 13a. A cylindrical member 16 is located on the outer peripheral side of the movable lead 12, the movable lead bolt 11, and the screw receiving portion 10, and has one end hermetically attached to the movable current collector 4 and the other end hermetically attached to the movable lead 12. A first bellows having a shape, which is extendable and contractable and keeps the outer peripheral side of the bellows in a vacuum.

The vacuum vessel 1 may be formed entirely of an insulating cylinder made of ceramic or the like. Either the guide pin 8 or the guide portion 9 must be made of an insulating material. For example, the guide pin 8 is formed of a ceramic such as alumina to maintain the slidability, and the guide portion 9 is formed of phosphor bronze. The guide pins 8 may be made of metal, and the surface thereof may be coated with a highly slippery nylon resin. The movable lead 12 is formed of a conductor. Therefore, when the guide part 9 is made of an insulating material, the guide part 9 and the movable lead 12 are naturally separate bodies.

In the vacuum variable capacitor having the above structure,
When adjusting the maximum capacitance value, the adjusting nut 13 is slightly rotated before the adjusting screw 15 is screwed into the screw hole 11 b of the movable lead bolt 11 (in the case of a right-handed screw, the clockwise rotation). The movable lead 12 is moved slightly below the maximum capacitance position where the tip 8a and the upper end surface 11d of the movable lead bolt 11 abut, and adjusted to the defined maximum capacitance value. This slight adjustment amount is determined by the degree of variation in the capacitance of the vacuum variable capacitor. Next, in this state, the adjusting screw 15 is inserted into the stepped portion 13c in which the contact surface of the head is formed between the screw hole 13a of the adjusting nut 13 and the large-diameter hole 13b.
The adjusting screw 15 is fixed to the movable lead bolt 11 with an adhesive or the like at this contact position to regulate the ascending position of the movable lead bolt 11. The adjusting screw 15 and the adjusting nut 13 are free.

As described above, by setting the rising position of the movable lead bolt 11, even if the maximum capacitance value of the manufactured vacuum variable capacitor varies, the maximum capacitance value can be set for each vacuum variable capacitor. A variable vacuum capacitor is obtained which can be adjusted and which meets the defined maximum capacitance value. Further, when the adjustment nut 13 is turned rightward from the maximum capacitance position, even if the adjustment nut 15 is turned to the left, the adjustment screw 15 comes into contact with the step 13c and the adjustment nut 13 cannot be turned to the left. In addition to serving as a stopper for preventing the adjustment nut 13 from coming off the movable lead bolt 11, it also prevents the capacitance value from exceeding the defined maximum capacitance value.

[0008] Also, in the adjustment of the capacitance of the vacuum variable capacitor, when is the adjustment nut 13 for example clockwise movable lead bolt 11 is lowered, the electrode plate F _1, F _2, ... and the electrode plate M _1, M _The capacitance decreases due to a decrease in the intersecting length of ₂ ,... Conversely, when the adjustment nut 13 is rotated counterclockwise, the capacitance increases.

Further, in the vacuum variable condenser, a force for pushing the movable lead bolt 11 upward always acts due to a differential pressure with respect to vacuum, so a similar force acts on the adjusting nut 13, and a surface pressure is applied to the outer surface of the screw receiving portion 10. Although the rotation of the adjustment nut 13 requires a large rotation torque, the bearing 14 is provided between the adjustment nut 13 and the outer surface of the screw receiving portion 10, so that the rotation becomes easy and a small rotation torque is required. . Further, since the screw receiving portion 10 is provided so as to protrude inward from the movable-side current collector 4, the movable lead bolt 11 is moved by the screw receiving portion 1.
Until the contact surface 11c of the movable lead bolt 11 comes into contact with the inner surface of the zero flange 10a, the size can be reduced. Further, the provision of the guide pins 8 and the guide portions 9 allows the movable electrode 7 to move in parallel with the fixed electrode 5 and stabilize the withstand voltage and the capacitance. The current of the vacuum variable capacitor is transferred from the fixed-side mounting conductor 3 to the fixed electrode 5.
Then, the current flows through the movable-side mounting conductor 6 and the movable lead 12 via the movable electrode 7, and flows to the movable-side current collector 4 via the bellows 16.

[0010]

As described above, in a vacuum variable capacitor, a current flows structurally through the first bellows 16, but the first bellows 16 is made of a thin metal (for example, a copper-based or stainless-based metal). Therefore, the current carrying capacity of the vacuum variable capacitor is determined by the first bellows 16.

On the other hand, in recent years, the capacity of a high-frequency power supply for semiconductor manufacturing equipment has been increased, and accordingly, the current of a vacuum variable capacitor has been required to be increased. For this reason, it is necessary to increase the power supply capability of the bellows 16, and the bellows 1
It was necessary to increase the diameter of No. 6 and increase the energized area.
However, when the diameter of the bellows 16 is increased, the self-closing force of the bellows 16 generated from the differential pressure between the vacuum side and the atmosphere side increases, the rotational torque of the adjusting nut 13 for adjusting the capacitance also increases, and the adjusting nut 13 When the motor is rotated by a motor, the size of the motor is also increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and a vacuum variable capacitor capable of increasing the current-carrying capacity without increasing the rotational torque of an adjusting nut for adjusting the capacitance. The purpose is to obtain.

[0013]

A vacuum variable capacitor according to a first aspect of the present invention is provided concentrically on the outer peripheral side of a first bellows, one end of which is attached to a movable-side current collector and the other end of which is attached. A cylindrical second bellows, which is attached to the movable-side mounting conductor or the movable lead and has a diameter larger than that of the first bellows, for supplying a current is provided.

According to a second aspect of the present invention, the second variable bellows is formed of one of copper, silver, stainless steel coated with copper, and stainless steel coated with silver.

A vacuum variable capacitor according to a third aspect is provided concentrically on the outer peripheral side of the first bellows, and has one end attached to the movable-side current collector and the other end attached to the movable-side attachment conductor or the movable lead. Provided with a helical conductive wire for conducting current.

In a vacuum variable capacitor according to a fourth aspect, the conductive wire is formed of copper or silver.

According to a fifth aspect of the present invention, there is provided a vacuum variable capacitor in which a conductive wire is formed in a belt shape.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view of a vacuum variable capacitor according to the first embodiment. Reference numeral 17 denotes a cylindrical second bellows provided concentrically on the outer peripheral side of a first bellows 16, one end of which is a movable side collector. The other end is airtightly attached to the conductor 4, and the other end is airtightly attached to the movable attachment conductor 6. Other configurations are the same as the conventional one.

In the above configuration, since the second bellows 17 has a larger diameter than the first bellows 16, it has a large current-carrying area, and almost all of the current flows through the second bellows 17 due to the skin effect of the high-frequency current. . As described above, since the second bellows 17 has a large energizing area, the energizing ability is improved, and a vacuum variable capacitor having a high energizing ability can be obtained. In addition, the first bellows 16 need only have a function of almost only separating the vacuum side and the atmosphere side, so that the diameter may be small, and the self-closing force due to the differential pressure between the vacuum side and the atmosphere side is small. The torque may be small. The second bellows 17 does not generate a self-closing force. In addition, since the vacuum in the vacuum vessel 1 is maintained double by the first and second bellows 16, 17, the reliability of the vacuum can be increased.

If the second bellows 17 is formed of any one of copper, silver, stainless steel coated with copper, and stainless steel coated with silver, since these have high conductivity, the current carrying capacity is high. This is because it is possible to further improve.

Embodiment 2 FIG. 2 is a longitudinal sectional view of a vacuum variable capacitor according to Embodiment 2 of the present invention. Reference numeral 18 denotes a spiral conductive wire provided concentrically on the outer peripheral side of a first bellows 16, one end of which is provided. The other end is attached to the movable-side mounting conductor 6 while being attached to the movable-side current collector 4. Other configurations are the same as the conventional one.

In the above configuration, the capacitor current is the first
Since the current flows through both the bellows 16 and the conductive wire 18, the current-carrying area increases, and the current-carrying ability improves. In addition, the first bellows 16 does not need to be large in diameter in order to increase the energization area, and may be kept small in diameter. Therefore, the self-closing force is small, and the rotation torque of the adjustment nut 13 may be small. In addition, since the conductive wire 18 has a spiral shape, it has elasticity and can follow the movement of the movable electrode 7.

If the conductive wire 18 is made of copper or silver having high conductivity, the current carrying capacity can be further increased.
Further, if the conductive wire 18 is formed in a belt shape, the energizing area increases, and the energizing capability can be improved.

In each of the above embodiments, the guide pin 8 is attached to the fixed-side mounting conductor 3 and the guide portion 9 is attached to the movable-side mounting conductor 6. However, the order may be reversed. Further, although the movable lead 12 is integrated with the guide section 9, it may be formed separately. Further, the upper end of the first bellows 16 is attached to the movable lead 12, but may be attached to the movable-side attachment conductor 6. Further, the upper end of the second bellows 17 and the upper end of the conductive wire 18 are attached to the movable-side mounting conductor 6, but may be attached to the movable lead 12. Further, the movable lead 12 and the movable lead bolt 11 may be integrated.

[0025]

As described above, according to the first aspect of the present invention, the second bellows is provided concentrically on the outer peripheral side of the first bellows. Can be. Further, since the first bellows which generates the self-closing force by the differential pressure may have a small diameter, the rotation torque of the adjusting nut can be reduced. Further, since the bellows are provided in double, the reliability of the vacuum can be improved.

According to the second aspect, since the second bellows is formed of a material having a high conductivity, it is possible to further enhance the current-carrying capacity.

According to the third aspect, since the spiral conductive wire is provided concentrically on the outer peripheral side of the first bellows, the energizing area can be increased and the energizing capability can be improved. Further, since the first bellows may be kept small in diameter, the self-closing force can be reduced, and the rotational torque of the adjusting nut can be reduced.

According to the fourth aspect, since the conductive wire is formed of a material having a good electrical conductivity, the current carrying capacity can be further enhanced.

According to the fifth aspect, since the conducting wire is formed in a belt shape, the energizing area can be increased, and the energizing ability can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a vacuum variable capacitor according to Embodiment 1 of the present invention.

FIG. 2 is a longitudinal sectional view of a vacuum variable capacitor according to a second embodiment.

FIG. 3 is a longitudinal sectional view of a conventional vacuum variable capacitor.

FIG. 4 is a partially enlarged view of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Vacuum container 2 ... Cylindrical part 3 ... Fixed side mounting conductor 4 ... Movable side current collector 5 ... Fixed electrode 6 ... Movable side mounting conductor 7 ... Movable electrode 8 ... Guide pin 9 ... Guide part 10 ... Screw receiving part 11 ... Movable lead bolt 12 ... Movable lead 13 ... Adjustment nut 16 ... First bellows 17 ... Second bellows 18 ... Conducting wire

Claims (5)

[Claims] 1. A fixed-side mounting conductor is provided at one end of a cylindrical portion having an insulating portion, and a movable-side current collector is provided at the other end of the cylindrical portion. A fixed electrode formed by attaching a plurality of concentric cylindrical electrode plates having different diameters, and a plurality of cylindrical electrode plates having different diameters so that the fixed electrode can be inserted into and removed from each cylindrical electrode plate in a non-contact manner. A movable electrode formed concentrically with the movable-side mounting conductor, a fixed-side mounting conductor and a guide pin provided at the center of the movable-side mounting conductor, and electrically insulated and slidably fitted with the guide pin. The guide portion, the screw receiving portion provided in the insertion hole provided in the center of the movable-side current collector, and the movable-side mounting conductor are integrally attached to the screw-receiving portion via a movable lead. With the movable lead bolt inserted, An adjusting nut that is screwed into the movable lead bolt and locked by the screw receiving portion, and that moves the movable electrode with respect to the fixed electrode by rotation; and an outer circumferential side of the movable lead bolt, one end of which is a movable-side current collector. And the other end is provided concentrically on the outer peripheral side of the first bellows, and the other end is attached to the movable-side mounting conductor or the movable lead. A vacuum variable capacitor which is mounted and has a second cylindrical bellows whose other end is mounted on a movable-side mounting conductor or a movable lead. 2. The vacuum variable capacitor according to claim 1, wherein the second bellows is formed of one of copper, silver, stainless steel coated with copper, and stainless steel coated with silver. 3. A vacuum container whose inside is evacuated by providing a fixed-side mounting conductor at one end of a cylindrical portion having an insulating portion, a movable-side current collector at the other end of the cylindrical portion, and a fixed-side mounting conductor. A fixed electrode formed by attaching a plurality of concentric cylindrical electrode plates having different diameters, and a plurality of cylindrical electrode plates having different diameters so that the fixed electrode can be inserted into and removed from each cylindrical electrode plate in a non-contact manner. A movable electrode formed concentrically with the movable-side mounting conductor, a fixed-side mounting conductor, a guide pin provided at the center of the movable-side mounting conductor, and an electrically insulated and slidable fit with the guide pin. The guide portion, the screw receiving portion provided in the insertion hole provided in the center of the movable-side current collector, and the movable-side mounting conductor are integrally attached to the screw-receiving portion via a movable lead. With the movable lead bolt inserted, An adjusting nut that is screwed into the movable lead bolt and locked by the screw receiving portion, and that moves the movable electrode with respect to the fixed electrode by rotation; and an outer circumferential side of the movable lead bolt, one end of which is a movable-side current collector. And the other end is provided concentrically on the outer peripheral side of the first bellows, and the other end is attached to the movable-side mounting conductor or the movable lead. A vacuum variable capacitor which is attached and has a helical lead wire whose other end is attached to a movable attachment conductor or a movable lead. 4. The vacuum variable capacitor according to claim 3, wherein the conductor is formed of copper or silver. 5. The vacuum variable capacitor according to claim 3, wherein the conductive wire has a band shape.