JPH06174131A - Vacuum valve - Google Patents

Abstract

PURPOSE:To prevent the occurrence of excessive deformation on a seal member, and provide a vacuum valve of long service life hardly giving leakage, wear and deterioration by converting the rotational motion of a rotary shaft into linear motion via a screw shaft and a nut body for driving a valve, and sealing the rotary shaft to be airtight. CONSTITUTION:When a rotary shaft 62 is driven with an electric motor, for example, in a counterclockwise direction, a screw shaft 63 connected to the shaft 62 also rotates in the same direction. Furthermore, a nut body 64 and a rectilinear shaft 61 connected thereto respectively travel an axial right direction, due to a screw wedge effect. In addition, a valve 30 moves right via a valve spindle coupling section 40, thereby closing the opening 25 of a vacuum vessel 20. In other words, the rotational motion of the shaft 62 is converted into linear motion via the screw shaft 63 and nut body 64 for driving the valve 30. In this case, a seal member 80 fitted to the rotational shaft penetration section of a shaft external tube 50 has the shaft 62 as an object for contact and seals the shaft 62, while being in contact with the rotational motion plane thereof or a motion plane in a seal line direction. Thus, the occurrence of excessive deformation on the member 80 can be eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to prevention of leakage of a vacuum valve opening / closing device used in a vacuum exhaust device or a vacuum container.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional vacuum valve. Reference numeral 30 is a disc-shaped valve body that opens and closes the opening 25 of the vacuum container 20.
A straight shaft 61 is connected to the valve body 30 via a valve shaft connecting portion 40. The rectilinear shaft 61 penetrates through the outer pipe 50 and is connected to the piston of the pneumatic cylinder 91. Off-axis tube 5
An O-ring 81 that hermetically seals the space with the rectilinear shaft 61 in 0
Two are provided. When air pressure is supplied to the chamber on the left side of the drawing in the pneumatic cylinder 91 to push the piston to the right, the linear shaft 61 and the valve element 30 move together with the piston to the right of the drawing. When the valve body 30 reaches the position shown by the chain line, the valve shaft coupling portion 40 presses the valve body 30 against the opening 25, and the valve body 30 hermetically seals the opening 25.

[0003]

Although the conventional vacuum valve is as described above, the O-ring 81 that hermetically seals the circumference of the straight advance shaft 61 is reciprocated in the axial direction because the straight advance shaft 61 in pressure contact moves reciprocally. Due to frictional force, a large internal stress or strain is generated in the O-ring 81, leakage is likely to occur, and wear and abrasion are large,
There were problems such as rapid deterioration and short life.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a vacuum valve having a long life which is less likely to cause leakage, wear, deterioration and the like.

[0005]

A vacuum valve according to the present invention comprises a valve body for opening and closing an opening of a vacuum container, a hollow linear shaft whose one end is connected to the valve body via a coupling portion, A nut body having a detent attached to the other end of the rectilinear shaft and a screw having a length exceeding the moving distance of the valve body are formed by screwing into the nut body and entering the hollow of the rectilinear shaft. A screw shaft, a rotary shaft having one end connected to the screw shaft and the other end connected to a rotary drive unit, and the linear shaft, the nut body, the screw shaft, and the rotary shaft, the straight shaft being inside the vacuum container. So that the one end extending to the vacuum container is airtightly fixed to the vacuum container and the other end is fitted to an outer shaft formed so that the rotation shaft penetrates, and the rotation stopper of the nut body is axially movable. A guide ridge axially provided on the inner surface of the outer shaft tube, and the rotation shaft of the outer shaft tube. Those comprising a seal member provided so as to hermetically seal between the shaft outer tube at a location that penetrates the rotary shaft.

[0006]

In the vacuum valve according to the present invention, when the rotary drive unit rotates the rotary shaft, the screw shaft connected to the rotary shaft also rotates. Since the detent of the nut body screwed to the screw shaft is fitted to the guide ridge so as to be movable in the axial direction, the nut body moves in the axial direction by the screw action when the screw shaft rotates. When the nut body moves in the axial direction, the rectilinear shaft connected to the nut body also moves in the axial direction, the rectilinear shaft moves the valve body through the coupling portion, and the valve body opens and closes the opening of the vacuum container. At this time, the seal member provided in the rotary shaft penetrating portion of the outer shaft tube contacts the rotary shaft, and seals by contacting with the motion surface in the seal line direction of the rotary motion, so that the seal member is deformed unreasonably. A large amount of internal stress does not occur, wear and wear of the seal member is small, leakage is small, and airtight sealing is performed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 20 is a vacuum container, and 30 is a valve body that opens and closes an opening 25 of the vacuum container 20. Valve body 30
Has a disc shape, and the valve shaft coupling portion 40 is provided at the center of the valve body 30.
Is provided, and the right end of the rectilinear shaft 61 in the figure is connected to the valve shaft coupling portion 40. The rectilinear shaft 61 has a hollow cylindrical shape, and a nut body 64 is fixed to the left end portion of the rectilinear shaft 61 in the drawing. Further, a screw shaft 63 that is screw-fitted into the nut body 64 is provided, the screw shaft 63 is connected to the left side of the drawing with the same axis center line, and a rotating shaft 62 is provided. The rotating shaft 62 is driven to rotate by an electric motor 92. It is configured to be. Further, the outer shaft 50 is provided so as to accommodate the straight shaft 61, the screw shaft 63, the nut body 64, and the rotating shaft 62, and the right end portion of the outer shaft 50 in the figure is hermetically fixed to the vacuum container 20 with a flange 52. Has been done. The rotary shaft 62 is rotatably supported by the outer shaft 50 by a radial bearing 55, and is supported by a thrust bearing (not shown) inside the electric motor 92 and near the radial bearing 55 so as not to move in the axial direction. A magnetic fluid seal 82 is provided as a seal member that hermetically seals between the rotary shaft 62 and the outer shaft 50 at a position where the rotary shaft 62 penetrates the end of the outer shaft 50. Of course, as a seal member,
Conventional sealing means such as an O-ring and a gland packing can also be used.

FIG. 2 shows details of the drive shaft portion. As shown in FIG. 1 and FIG. 2, the hollow cylindrical straight-moving shaft 6 is provided in the outer shaft tube 50.
1 is provided so as to be movable in the axial direction, the movable range in the axial direction of the rectilinear shaft 61 is greater than or equal to the required moving range of the valve body 30, and the nut body 64 fixed to the rectilinear shaft 61 is Since the moving range is also the opening / closing required moving range of the valve body 30 or more, the length of the screw shaft 63 is also a required length that is not less than the opening / closing required moving range of the valve body 30. In this example,
As shown in FIG. 2, the screw shaft 63 is a ball screw shaft,
Inside the nut body 64, a ball female screw that is screwed into the ball screw of the screw shaft 63 is formed, and a large number of balls (steel balls) into which the screw shaft 63 and the nut body 64 are fitted in the ball screw recesses. ), So that the nut body 64
A large number of balls are circulated therein.

As shown in FIG. 2, one or more guide ridges 57 extending in the axial direction are provided on the inner surface of the outer tube 50, and the guide ridge 57 is provided on the outer peripheral surface of the nut body 64. A rotation stopper 67 that is slidably fitted to the nut body 6 is provided.
Numeral 4 is non-rotatably supported by the outer shaft tube 50 so as to be slidable in the axial direction. The range of attachment of the guide ridge 57 is the nut body 6
4 is the movable range, that is, the required opening / closing movement range of the valve body 30 or more.

Next, the operation of the embodiment shown in FIGS. 1 and 2 will be described. The figure shows the open state of this vacuum valve. By rotating the rotary shaft 62 counterclockwise when viewed from the left side of the drawing by the electric motor 92, which is the rotary drive unit of the vacuum valve, the screw shaft 63 connected to the rotary shaft 62 also rotates counterclockwise. . The rotary shaft 62 is axially immovably supported by thrust bearings before and after the radial bearing 55 and inside the electric motor 92, and the screw shaft 63 connected to the rotary shaft 62 is also immovable in the axial direction. . Since the detent 67 of the nut body 64 screwed onto the screw shaft 63 is fitted in the guide projection 57 of the outer tube 50 so as not to rotate and slidably in the axial direction, the screw shaft 63 is counterclockwise. If the screw shaft 63 rotates, the screw shaft 63 cannot move in the axial direction, and the nut body 64 is moved to the right in the axial direction by the wedge action of the screw. When the nut body 64 moves in the axial direction, the linear shaft 61 connected to the nut body 64 also moves to the right in the axial direction, and the linear shaft 61 moves the valve body 30 to the right side in the drawing via the valve shaft coupling portion 40. Move towards. When the valve body 30 moves to the position shown by the chain line in FIG. 1, the valve shaft coupling portion 40 operates to move the valve body 30 to the vacuum container 20.
The opening 25 is closed by pressing it.

When opening this vacuum valve, in FIG. 1 and FIG. 2, first, the valve shaft coupling portion 40 is operated to open the valve body 30 which covers and closes the opening 25 of the vacuum container 20. Keep away from. Next, the electric motor 92 is rotated in the opposite direction to rotate the rotating shaft 62 and the screw shaft 63 clockwise. Then, the nut body 64 screwed to the screw shaft 63 moves to the left in the axial direction in the drawing by the wedge action of the screw, and the straight shaft 61 moves.
And the valve body 30 is moved to the left through the valve shaft coupling portion 40, and the valve body 30 is opened.

In the above-described operation, the seal member 80 provided in the rotary shaft penetrating portion of the off-axis pipe 50 is the rotary shaft 62 that comes into contact with the seal member 80, and seals while contacting a rotary motion surface in the seal line direction. Therefore, the sealing member 8
When an O-ring, a gland packing or the like is used as 0, the seal member 80 is not unduly deformed, and a large internal stress or internal strain is not generated. The gap between the shaft 62 and the shaft 62 is small, has a long life, and is airtightly sealed. In the vacuum valve shown in FIG. 1, the magnetic fluid seal 82 is used as the seal member 80.
However, since the vacuum valve is configured to hermetically seal the rotary shaft, there is no risk of the magnetic fluid moving in the axial direction, and the magnetic fluid seal 82 can be easily adopted. it can.

In the above embodiment, the ball screw shaft 63 and the ball nut body 64 are used as means for converting the rotary motion of the rotary shaft 62 into a linear motion in the axial direction, but a slide screw transmission means may be used. . However, in an apparatus related to vacuum, the presence of lubricating oil or the like may deteriorate the vacuum performance, so it is desirable to employ ball screw transmission means that does not require lubricating oil or the like.

Further, although a magnetic fluid seal 82 is adopted in FIG. 1 as the seal member 80 for hermetically sealing the outer shaft tube 50 and the rotary shaft 62, of course, together with the magnetic fluid seal 82 or with the magnetic fluid seal 82. Instead of the seal 82, a conventional sealing means such as an O-ring and a gland packing can be used.

Further, in the above embodiment, the guide protrusion 5 provided on the outer shaft tube 50 serves as a rotation stop guide means for the nut body 64.
7 is combined with the detent 67 that is fitted onto the guide ridge 57 provided on the nut body 64. However, a guide groove is provided instead of the guide ridge 57 and the detent 67 is fitted into the guide groove. It may be a convex shape. Further, a motor that operates by air pressure may be used instead of the electric motor 92.

[0016]

As described above, according to the present invention, the rotary motion of the rotary shaft is converted into the linear motion by the screw shaft and the nut body to drive the valve body and hermetically seal the rotary shaft. With this configuration, there is no leakage and wear and wear of the seal member can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a vacuum valve according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view showing a drive shaft portion of a vacuum valve according to an embodiment of the present invention.

FIG. 3 is a vertical sectional view of a conventional vacuum valve.

[Explanation of symbols]

20: Vacuum container, 25: Opening, 30: Valve body, 40: Valve shaft coupling part, 50: Outer shaft tube, 57: Guide ridge, 61: Linear shaft, 62: Rotating shaft, 63: Screw shaft, 64: Nut body, 67: rotation stop, 80: seal member, 82: magnetic fluid seal, 92: electric motor.

Claims (1)

[Claims] 1. A valve body which opens and closes an opening of a vacuum container, a hollow straight advance shaft whose one end is connected to the valve body via a coupling portion, and a detent attached to the other end of the straight advance shaft. A nut body having the same, a screw shaft screw-fitted into the nut body and entering the hollow of the linear shaft to form a screw having a length exceeding the moving distance of the valve body, and one end thereof is connected to the screw shaft. The other end accommodates the rotary shaft connected to the rotary drive unit, the linear shaft, the nut body, the screw shaft and the rotary shaft, and one end of the linear shaft extending into the vacuum container is airtightly fixed to the vacuum container. The other end is provided in the axial direction on the inner surface of the outer shaft tube so that the rotation stopper of the nut body is fitted movably in the axial direction with the outer shaft tube formed so as to penetrate the rotary shaft. The guide ridge and the outer shaft of the outer pipe at a position where the rotary shaft penetrates. A vacuum valve comprising a sealing member provided so as to hermetically seal.