JPS6344911Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an air switch that converts rotational motion into linear motion to turn on and off electric circuits.

Conventionally, this type of air switch was developed in the 1970s.
There was one shown in Publication No. 21663.

In this conventional air switch, a support insulator containing a rotary insulator is vertically fixed to a support base that houses an operating mechanism, and a case is provided above the support insulator, and a case is provided on both sides of the case. The insulator tube containing the fixed side electrode was fixed. Further, a movable conductor as a movable side electrode having a rack on the outer surface of the base end is slidably provided on the support frame provided in the case, and a position where the intermediate gear meshes with the rack of the movable side electrode. Further, an operating gear was fixed to the upper part of the rotary insulator and meshed with the intermediate gear. Then, when the operating mechanism is opened or closed and the rotary insulator rotates, the movable conductor slides within the case via the operating gear and the intermediate gear, and operates to close or open the fixed electrode. was.

However, since conventional air switches did not have a structure that linearly guided the sliding movement of the movable conductor, a complex gear mechanism was required as a motion conversion mechanism to accurately move the movable conductor in a straight line. It was very difficult to adjust the arrangement of each gear and the movable conductor. If this adjustment is insufficient, the movable conductor may not be able to move accurately in a straight line, and there is a possibility that the switch may not be reliably closed or opened.

The object of this invention is to provide an air switch which reliably moves the movable conductor in a straight line by guiding and restricting the movement of the movable conductor to a straight line using a guide cylinder, and which makes it possible to employ a link mechanism which is simple in structure and can impart a large momentum to the movable conductor as a motion conversion mechanism.

An embodiment embodying this invention will be described below with reference to the drawings. First, the external operation mechanism for opening and closing this air switch will be explained according to FIGS. 1 to 4. The drive shaft 3 is rotatably supported through the support base 2, and a pair of engaging portions 4a are provided at the inner end thereof.
A clutch plate 4 having a clutch plate 4b is fixed to the clutch plate 4, and an operating handle 5 for manual operation is fixed to the lower part of the clutch plate 4, which is suspended from the lower surface of the support base 2.

A passive shaft 6 having the same axis as the drive shaft 3 is rotatably supported in the support stand 2 above the drive shaft 3, and the pair of engaging portions 4 are attached to the lower end of the passive shaft 6.
An engaging piece 7 is fixedly connected to the clutch plate 4 so as to be able to rotate independently between a and 4b. The engaging piece 7 is engaged with one engaging part 4a in the closed state shown in FIG. 4, and is engaged with the other engaging part 4b in the open state shown in FIG.

A drive lever 8 whose distal end extends horizontally is fixed at its base end to the upper end of the driven shaft 6, and one end of a driven link 9 is rotatably attached to the upper end of the drive lever 8. . At the other end of the driven link 9, one end of a reversing link 11 is rotatably fixed to a support shaft 10 rotatably provided in the support base 2 in a horizontal manner at the center. There is. The other end of the reversing link 11 is rotatably engaged with the other end of a closing spring 12, which is a compression spring whose one end is rotatably engaged within the support base 2.

In the open state shown in FIG. 3, the shaft attachment point P between the drive lever 8 and the driven link 9 is a line connecting the base end of the drive lever 8 and the other end of the driven link 9 (indicated by a chain line in the figure). ), and when the shaft attachment point P exceeds the dead center, the closing spring 12 urges the reversing link 11 in a direction tangent to its rotation locus. Closing spring 1
The engagement position of one end of 2 is set.

The operating lever 13 whose base end is fixed to the support shaft 10 has a distal end extending horizontally, and an interphase connecting rod 14 extending horizontally in the longitudinal direction of the support base 2 is rotated at the distal end. It is movably pivoted. Connecting levers 15, which are arranged horizontally at predetermined intervals for each phase, are rotatably attached to the interphase connecting rod 14 at one end, and the supporting base 2 is attached to the other end of each connecting lever 15. A rotation shaft 16 is fixedly supported through the shaft so as to be rotatable therethrough.
Note that the rotation shaft 16 is provided vertically, and its upper portion protrudes from the upper surface of the support base 2.

Next, the operation of the external operating mechanism constructed as described above will be explained with reference to the schematic diagrams of Figs. 3 and 4. First, in the case of performing a quick closing operation in the open state shown in Fig. 3, when the operating handle 5 is rotated in the direction of the arrow in the figure to rotate the drive shaft 3 in the same direction, the engaging piece 7 engaged with the other engaging portion 4b of the clutch plate 4 is rotated,
At the same time, the drive lever 8 is rotated. When the pivot point P of the drive lever 8 passes the dead point, the other end of the reversing link 11 is suddenly rotated by the spring force stored in the closing spring 12. Then, the operating lever 13 is rotated in the direction of the arrow via the support shaft 10 to which the reversing link 11 is fixed, and the connecting levers 15 of each phase are simultaneously rotated in the direction of the arrow via the inter-phase connecting rods 14, and at the same time, the rotating shaft 16 is suddenly rotated in the closing direction.

Note that when the shaft attachment point P passes the dead center, the spring force of the closing spring 12 acts in a direction perpendicular to the reversing link 11, so the spring force of the closing spring 12 acts most effectively on the reversing link 11. do.

On the other hand, due to the rapid rotation of the reversing link 11, the drive lever 8 is also rotated in the direction of the arrow in the figure via the driven link 9, and at the same time, the passive shaft 6 to which the drive lever 8 is fixed is rotated. Then, the engagement piece 7 that was engaged with the other engagement part 4b is disengaged from the engagement part 4b and can rotate independently until it is engaged with the one engagement part 4a. .

Next, a case will be described in which the above-described operation causes the external operating mechanism in the closed state as shown in FIG. 4 to be opened. First, when the operating handle 5 is rotated in the direction of the arrow in FIG. The drive lever 8 and the driven link 9 are rotated in the direction of the arrow. Then, the reversing link 11
is rotated in the direction of the arrow against the spring force of The shaft 16 is rotated in the opening direction.

When the shaft attachment point P between the drive lever 8 and the driven link 9 stops at a position slightly moved beyond the dead center, this external operating mechanism is held in the open state shown in FIG. Sufficient spring force is stored in the closing spring 12.

Next, regarding the air switches arranged for each phase on the support base 2 in correspondence with the rotation shaft 16, only one phase will be explained according to FIGS. 5 to 12. The metal case 20 of the air switch is formed into a box shape with a watertight structure, and a set of motion conversion link mechanisms for converting rotational motion into linear motion is housed therein. The upper end of the solid support insulator 21 is fixed perpendicularly to the upper surface of the support base 2, and a pair of outer surfaces facing perpendicular to the longitudinal direction of the support base 2 are each provided with a solid support insulator 21. A support cylindrical portion 20a having a female thread formed on the inner periphery is symmetrically provided to protrude outward, and a mounting cylinder 22 is provided on each outer surface thereof to concentrically surround the support cylindrical portion 20a.

Further, on the other side of the lower surface of the metal case 20, a mounting hole 23 that communicates between the inside and outside of the metal case 20 is provided at a position coaxial with the rotation shaft 16, and the mounting hole 23 is made watertight with an O-ring 24. A cylindrical bearing 25, which is maintained at a constant temperature, is fixed. The bearing 25 has an operating shaft 2 whose upper end is inserted into the metal case 20.
6 is rotatably fitted and supported by an O-ring 27 in a watertight state, and a solid rotary operation insulator whose lower end is vertically fixed to the upper end of the rotation shaft 16 is attached to the lower end of the operation shaft 26. The upper end of 28 is fixed.

The solid rotationally operated insulator 28 and the solid support insulator 21 are vertically arranged vertically in a direction perpendicular to the longitudinal direction of the support base 2, and both solid insulators 2
The upper ends of the metal case 20, the mounting cylinder 22, and the outer surface of the operating shaft 26 are coated with insulation as shown by the two-dot chain line in FIG.

A metal case 20 is located above the operating shaft 26.
The inserted part has a cylindrical part 29 in which a symmetrical plate-shaped operating lever 29 is provided in the center.
A is fitted unrotatably through the key 30 at the cylindrical portion 29a, and on the upper surface of the cylindrical portion 29a is an annular retainer loosely fitted to prevent it from coming off with respect to the retaining bolt 31 screwed onto the upper end of the operating shaft 26. A plate 32 is abutted so as to be relatively movable.

At symmetrical positions on both ends of the operating lever 29, connecting links 33 whose lengths can be adjusted are rotatably attached at one end. The metal case 20
A fixed shaft 35 is inserted into and supported by a pair of support protrusions 34 protruding from one side of the inner bottom surface, and a movement amount expanding link 36 is rotatably attached at the base end to both ends of each of the protrusions 34. The connecting links 33 are individually rotatably attached to the central portion of the movement amount expanding link 36 . Note that the pair of movement amount expanding links 36 are attached symmetrically to each other with respect to the fixed shaft 35.

An intermediate link 37 is rotatably supported at one end at the distal end of each operation amount expansion link 36, and the other end of each intermediate link 37 is electrically conductive, and a fitting cylinder portion 38a is provided at the distal end. Drive member 38 formed
is rotatably attached at the proximal end. A metal case 20 is provided on the upper surface of each drive member 38.
A pair of flexible conductor pieces 3 electrically connected to each other at their upper ends fixed on the inner upper surface of the
9 are screwed onto the lower ends of each drive member 38, and a slit 40 with an open end is formed along the axial direction in the side surface of the fitting cylindrical portion 38a of each drive member 38.

Next, to explain the operation of the motion conversion link mechanism housed in the metal case 20 as described above, first, in the closed state shown in FIGS. 6 and 7, the rotation shaft 16 rotates in the opening direction. Then, the operating lever 29 is integrally rotated in the direction of the arrow in FIG. 7 via the solid rotary operating insulator 28 fixed to the rotating shaft 16 and the operating shaft 26. Then,
A connecting link 3 pivoted to both ends of the operating lever 29
3, each operation amount expansion link 36 connects to the fixed shaft 35.
are rotated in opposite directions about
It is enlarged by the ratio of the length to the pivot point and is transmitted to the intermediate link 37, and the intermediate link 37 is rotated by the enlarged movement amount. The rotation of the intermediate link 37 is transmitted to the drive member 38 as a linear motion.

In this way, the drive member 38 whose rotational movement of the rotational shaft 16 is converted into a linear movement is linearly moved in the direction of the arrow in FIG. 7 and stopped at the open position shown in FIG. Ru.

Further, when the rotation shaft 16 is rotated in the closing direction in the open state shown in FIG.
Since the rotation is performed rapidly, each member is rapidly driven in the opposite direction to that in the opening operation, and the driving member 38 is rapidly moved linearly to the closing position shown in FIG.

Next, a cylindrical hollow is horizontally adhesively fixed to each mounting cylinder 22 of the metal case 20 at its base end, and forms a T-shaped air switch together with the solid insulators 21 and 28. The opening/closing contact section housed in the inner cavity of the insulator 41 will be explained with particular reference to FIGS. 9 to 12.

An external wire connection terminal 42 is fixed to the outer end of the hollow insulator 41 in a watertight manner, and an annular protrusion 43 having an annular groove 43a recessed in the inner end surface is formed at the center of the inner end of the connection terminal 42. At the center of the annular protrusion 43, a fixed conductive rod 44 having a swollen portion 44a formed near the base end is screwed and bonded at the base end. In the portion of the fixed conductive rod 44 inserted into the annular projection 43, a small diameter portion 44b serving as an adhesive reservoir is provided on the circumferential side near the inner end surface of the annular projection 43.
is formed on the circumferential side of the annular protrusion 43 to ensure electrical conduction between the conductive rod 44 and the terminal fitting 42, and the conductive rod 44 is formed on the annular protrusion 4.
Conductive screw 4 to reliably prevent separation from 3
5 is screwed into contact with the conductive rod 44 at its tip.

A cylindrical fixed electrode 46 that is always pressed against the circumferential side of the conductive rod 44 at the inner periphery of the base end is fitted into the fixed conductive rod 44 so as to be movable in the axial direction. An arc extinguishing rod 47 is screwed and bonded to the base end of the arc extinguishing rod 47 via a resin screw 48. A cylindrical internal shield electrode 49 screwed into the resin screw 48 is buried inside the base end of the arc extinguishing rod 47, and a small diameter portion formed at the center of the resin screw 48 is embedded inside the electrode 49. An enlarged diameter space 47a forming an adhesive reservoir is provided corresponding to 48a. On the other hand, a plurality of slits are formed at the base end of the fixed side electrode 46, and
An annular spring 50 is wound around the circumferential side of the proximal end portion to ensure that the fixed electrode 46 is energized with respect to the fixed conductive rod 44 .

A cylindrical locking member 51 is screwed on the inner periphery of the distal end of the stationary electrode 46 on the circumferential side near the proximal end, and the locking member 51 has a locking member 51 fitted in the annular groove 43a of the annular projection 43 at the proximal end thereof. A cylindrical stopper part 51a is formed which comes into contact with the filled cushioning material 52 at its base end surface, and an engagement groove 5 is formed on the circumferential side of the distal end thereof.
1b is formed in a circular shape. The other end of a quick-cutting spring 53, which is a tension spring whose one end is attached to the circumferential side of the annular projection 43, is attached to the circumferential side of the central part of the locking member 51, and the other end of the quick-cutting spring 53 is fixed to the circumferential side of the central part of the locking member 51. Even in this state, the stopper portion 51a is brought into contact with the buffer material 52, and the base end portion of the fixed side electrode 46 is brought into pressure contact with the enlarged diameter portion 44a of the fixed conductive rod 44.

The engagement groove 51b of the locking member 51 is formed with a plurality of locking pieces 54 which are divided along the axial direction so as to have a cylindrical shape as a whole, and the tips thereof are expandable. A locking member 55 is rotatably press-fitted on the inner periphery of the proximal end, and each of the locking pieces 54
A tapered surface 54a whose diameter increases toward the tip is formed at the tip, and a locking claw portion 54b that projects inward is formed on the inner periphery of the tip. An annular spring 56 is wound around the outer periphery of the proximal end of the locking member 55 to prevent each of the locking pieces 54 from separating from the locking member 51, and an annular spring 57 is wound around the outer periphery of the distal end thereof. is wrapped.

Note that the fixed conductive rod 44 and the fixed electrode 46 constitute a rod-shaped male contact forming a fixed contact,
Also, the outer end of the hollow insulator 41 and the external wire connection terminal 4
2 is covered with an insulating cap.

A movable conductive rod 61 disposed opposite to the arc extinguishing rod 47 is fixed at the base end of the driving member 38, and a diameter-reduced attachment portion 61a is formed at the distal end of the conductive rod 61. An annular support member 62 is fitted to the base end side of the mounting portion 61a, and a cylindrical external shield electrode 63 is fixed to the outer periphery of the support member 62 at the base end. A pair of engagement holes 63a and 63b are formed through the base end and the distal end of the shield electrode 63, respectively.

Engagement hole 6 on the base end side of the external shield electrode 63
3a, as shown in FIG.
4 is slidably inscribed on the inner surface of a resin guide cylinder 65 screwed onto the inner circumference of the support cylinder portion 20a of the metal case 20 at the outer circumference of the base end. The length of the guide cylinder 65 is set so that its tip does not come into contact with the live part in the open state, and its tip engages with the tapered surface 54a of the locking piece 54, thereby forming a locking member. A cam surface 65a that expands the distal end of the cam 54 is formed obliquely so that the diameter decreases toward the distal end.

An arc-extinguishing tube 66 is fitted at the distal end of the external shield electrode 63, and the arc-extinguishing cylinder 66 is provided with a pair of engagement claws 66a that engage with the distal engagement hole 63b of the shield electrode 63 at the proximal end. A locking recess 66b that can be engaged with and detached from the locking claw portion 54b of the locking piece 54 is formed in a circumferential manner on the outer periphery of the distal end thereof. An annular spring 67 for preventing detachment is wound around the base end of the arc extinguishing tube 66, and when the arc extinguishing tube 66 is in the closed state, the fixed side electrode 46,
and is externally fitted onto the arc extinguishing rod 47 with a narrow gap.

A plurality of slits are formed at both ends of the distal end side of the mounting portion 61a of the movable conductive rod 61, and a movable side electrode 68 forming a cylindrical female contact forming a movable conductor together with the movable conductive rod 61 is based. The movable side electrode 68 is fitted at its end portion, and the distal end portion of the movable side electrode 68 is formed to fit into the fixed side electrode 46 so as to be able to come into contact with and separate from it. Annular springs 69 and 70 are wound around the proximal end and the distal end of the movable electrode 68, respectively, to ensure energization.

The tip of the external shield electrode 63 is formed to protrude from the tip of the movable electrode 68 toward the fixed electrode 46, and the support member 62 and the movable electrode 68 are formed at the tip of the mounting portion 61a of the movable conductive rod 61. Set screw 71 for preventing detachment from the mounting portion 61a
are screwed together.

Next, the operation of the opening/closing contact portions constructed as described above and housed in the respective inner cavities of the pair of hollow insulators 41 will be explained.

First, FIGS. 6 and 9 show a closed state, and in this state, the external wire connection terminal 42
→ Expanded diameter part 44a of fixed conductive rod 44 → Fixed side electrode 4
One electric path is formed from 6→movable side electrode 68→movable conductive rod 61→drive member 38→conductor piece 39, and the opening/closing contact section provided symmetrically on the other hollow insulator 41 has, symmetrically to the above, Conductor piece 39 → drive member 38
→...→An electric path for the external wire connection terminal 42 is formed, and furthermore, both conductor pieces 39 are electrically connected as described above. In this state, each latching claw portion 54b of the latching member 55 is connected to the arc extinguishing cylinder 6.
Since the hooking member 55 is hooked to the hooking recess 66b of No. 6, the hooking member 55 is movable integrally with the arc extinguishing cylinder 66.

Now, in the closed state shown in FIG. 9, when the driving member 38 is driven in the opening direction shown by the arrow in FIG. The arc extinguishing cylinder 66, which is fixed to the conductive rod 61 via the shield electrode 63, is moved approximately linearly in the same direction by being slidingly guided by the inner surface of the arc extinguisher 65 (as shown by the arrow in FIG. 9). will be moved to. Then, the locking member 51 is moved in the same direction through the locking member 55 hooked to the arc extinguisher cylinder 66 against the spring force of the quick-cut spring 53, and the fixed side electrode 46 and the extinguisher are moved in the same direction. The arc rod 47 is moved in the same direction, and the base end of the fixed electrode 46 comes off the enlarged diameter portion 44a of the fixed conductive rod 44, and smoothly slides into contact with the circumferential side of the tip portion.

Then, when the driving member 38 is moved by a predetermined amount, each tapered surface 54 of the hooking member 55 that has been moved integrally with the arc extinguishing tube 66, as shown in FIG.
a is the cam surface 65 at the tip of the insulating cylinder 65 in the fixed position
a and the distal end of the latching member 55 is expanded, so that the latching claw portion 54b is removed from the latching recess 66b of the arc extinguishing tube 66. Then, the fixed side electrode 46, the arc extinguishing rod 47, the locking member 51, and the locking member 55 are rapidly moved in the direction of the arrow in the figure by the spring force of the extended quick-cut spring 53, and as a result of this movement, the fixed side The electrode 46 is rapidly separated from the movable electrode 68, and rapid cutting is performed.

Incidentally, when the fixed side electrode 46 is separated from the movable side electrode 68, the arc generated between the two electrodes 46 and 68 is extinguished by the cooperation of the arc extinguishing rod 47 and the arc extinguishing tube 66, and 46 and 68 are provided with shield electrodes 49 and 63 that protrude from their respective tips so that they cannot move relative to each other, so that both electrodes 46 and 68
The potential concentration on the tips of the electrodes 4 is weakened, which further suppresses restriking, so that both electrodes 4
The separation between 6 and 68 allows the current to be cut off quickly. Furthermore, during the slit arc extinguishing process, arc extinguishing gas containing carbon and having a low dielectric strength is generated in the guide cylinder 65, and the hollow insulator 41, where insulation performance is important, is generated in the guide cylinder 65.
Since it is not released into the lumen side, deterioration in insulation due to internal contamination of the hollow insulator 41 is prevented. Furthermore, in this embodiment, since the movable side electrode 68 has a female structure, if at least one of the movable conductive rod 61 and the support member 62 is provided with a gas venting structure, the arc-extinguishing gas can be directed to the metal case 20 side. It becomes possible to release it.

Then, the arc extinguishing cylinder 66 and the movable side electrode 68
Each of the members 46, 47, 51, 55 separated from
returns to the original position shown in FIGS. 9 and 12. Note that when returning, the stopper portion 51a of the locking member 51 is quickly moved toward the connection terminal 42, but since a cushioning material 52 is provided at the portion where the stopper portion 51a hits, there is no possibility of a collision. This prevents the connection terminal 42 and the locking member 51 from being damaged due to the impact.

On the other hand, the movable conductive rod 61, the external shield electrode 63, and the arc extinguishing tube 6 have been detached from the hooking member 55, etc.
6, and the movable side electrode 68 in the same direction as above (the 11th
(indicated by an arrow in the figure), and the drive member 37 stops at the open position shown by the two-dot chain line in FIG. 6 (the position shown in FIG. 12).

In this open state, the guide cylinder 65 of this embodiment does not come into contact with the live part, so no potential difference is generated in the axial direction of the guide cylinder 65, and the risk of surface tracking is prevented.

Next, in the open state shown in FIG. 12, when the driving member 38 is rapidly driven in the input direction (the direction opposite to the direction of the arrow shown in FIG. 6), the extinguisher fixed to the movable conductive rod 61 The arc cylinder 66 and the movable electrode 68 are guided to the insulating cylinder 65 via the guide member 64 attached to the external shield electrode 63, and are fitted into the fixed electrode 46 and the arc extinguishing rod 47. As shown in the figure, the arc extinguishing cylinder 66 has a latching recess 66b.
The movable electrode 6 is quickly latched to each latching claw portion 54b of the latching member 55.
8 is quickly fitted into the stationary side electrode 46 at its tip and is quickly inserted.

As detailed above, the air switch of this invention has hollow insulators installed horizontally on both sides of the metal case.
An external wire connection terminal is fixed at the outer end of each hollow insulator, a rod-shaped male contact with an arc-extinguishing rod at the tip is provided at the inner end of the connection terminal, and a movable conductor is fitted into the male contact. A mating female contact is provided, an arc extinguisher is provided at the tip thereof, and a resin guide cylinder for guiding the movable conductor is fixedly supported on the metal case as a means for regulating linear movement in the movable conductor. This makes it possible to use a link mechanism that has a simple structure and can give a large amount of momentum to the movable conductor as a motion conversion mechanism that converts rotational motion into linear motion.
This is a practically preferable idea for an air switch because it has the effect of making the movable conductor perform an effective linear motion.

[Brief explanation of the drawing]

Figure 1 is a side view showing a state in which an air switch according to an embodiment of this invention is mounted on a column;
The figure is a diagram of the operating mechanism, Figures 3 and 4 are schematic diagrams showing the operating mechanism, Figure 5 is a front view, and Figure 6 is a partially broken front view showing the interior of the metal case and hollow insulator. 7 and 8 are plan sectional views of the main parts showing the movement conversion link mechanism, FIGS. 9, 11, and 12 are front sectional views showing the opening/closing contact part, and FIG. 10. FIG. 2 is an exploded perspective view showing how the piston and the arc extinguisher are attached to the external shield electrode. Support stand 2, metal case 20, solid support insulator 2
1. Solid rotating insulator 28, drive member 38, conductor piece 39, hollow insulator 41, external wire connection terminal 42,
Fixed conductive rod 44, fixed side electrode 46, arc extinguishing rod 47,
A locking member 51, a quick cut spring 53, a locking member 55,
A movable conductive rod 61, a piston 64, a guide cylinder 65, an arc extinguisher 66, and a movable electrode 68.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. When the movable conductor moves linearly toward the open side, the force is accumulated in the quick-cutting spring, and when the movable conductor moves a predetermined distance, the engagement of the quick-cutting spring is disengaged. In a switch equipped with a quick-cut mechanism on the fixed contact side that opens and cuts off the current, hollow insulators are installed horizontally on both sides of the metal case, and external wire connection terminals are attached to the outer ends of each hollow insulator. A rod-shaped male contact with an arc-extinguishing rod at the tip is provided at the inner end of the connecting terminal, and a female contact that fits into the male contact is provided on the movable conductor. What is claimed is: 1. An air switch comprising: an arc-extinguishing tube; and a guide cylinder made of resin for guiding the movable conductor as means for regulating linear movement of the movable conductor, fixedly supported on the metal case. 2. Registration of a utility model characterized in that the movable conductor has a piston fixed to its tip, and the piston is inscribed in a resin guide cylinder so as to obtain approximate linear motion of the movable conductor. An air switch according to claim 1. 3. The guide cylinder is fixedly supported by a metal case at its base end, and its distal end is arranged so as not to come into contact with a live part in an open state. The air switch described.