JP2009074681A - Vacuum opening and closing valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance durability in a vacuum opening and closing valve having a gap between the peripheral surface of a piston and the inside circumferential surface of a cylinder sealed tightly with a bellofram following operation of a piston motions and opened and closed by driving the piston with fluid. <P>SOLUTION: The vacuum opening and closing valve 10 is connected between a vacuum vessel 2 and a vacuum pump 5, and controls the vacuum pressure in the vacuum chamber 2 by changing the degree of opening of an O-ring 79 as a valve element relative to a valve seat 73. The specified gap between the peripheral surface of the piston 40 and the inside surface of the cylinder 30 is tightly sealed with the bellofram 50 following movement of the piston 40, and can be opened and closed by driving the piston 40 with fluid. The bellofram 50 is formed with a prescribed inclination angle θ2, the periphery of the piston 40 is formed with a prescribed inclination angle θ, and the inside diameter of the bellofram abutting to the piston when the valve element is positioned abutting to the valve seat is equal to the outside diameter of the piston. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vacuum on-off valve that is connected between a vacuum vessel and a vacuum pump and controls the vacuum pressure of gas in the vacuum vessel by changing the opening.

  Conventionally, for example, in a semiconductor manufacturing process, a vacuum pressure control system for alternately supplying and exhausting process gas and barge gas in a vacuum chamber in which a wafer is arranged has been proposed. In such a vacuum pressure control system, a vacuum opening / closing valve is connected between the vacuum chamber and the vacuum pump. This vacuum on-off valve controls the vacuum pressure of the process gas supplied into the vacuum chamber by changing the opening degree (see Patent Document 1).

A conventional vacuum on-off valve will be briefly described with reference to FIGS. FIG. 11 is a cross-sectional view showing a vacuum on-off valve 100 configured in the vacuum pressure control system of Patent Document 1 proposed by the present applicant. FIG. 12 is an enlarged view of a portion R in FIG. 11 and is an explanatory diagram for explaining the form of the bellophram 150 in the valve-closed state. FIG. 13 is a cross-sectional view showing a conventional belofram 150. FIG. 14 is an explanatory view for explaining the weave of the base fabric 151B in the conventional belofram 150. FIG.
In the vacuum on-off valve 100, when the driving air is supplied into the air accommodating chamber AS and the piston 140 rises (upward in FIG. 11), the poppet valve body 176 connected to the piston 140 via the piston rod 147 is moved to the piston 140. Ascending in the stroke direction, the poppet valve element 176 is opened away from the valve seat 173. The piston 140 is driven in a non-contact manner within the single acting pneumatic cylinder 130 in order to prevent the occurrence of stick slip. A gap 145 between the piston 140 and the single-acting pneumatic cylinder 130 is sealed with a bellophram 150 that follows the operation of the piston 140 to ensure airtightness in the air accommodating chamber AS.

  The bellophram 150 has a substantially trapezoidal cross section as shown in FIG. 13 when viewed from the bore direction of the piston 140. The belofram 150 is formed by embedding a base fabric 151B such as polyester in rubber by insert molding. As shown in FIG. 14, the base fabric 151B has plain weave meshes in which one yarn is crossed in a lattice shape one by one in the longitudinal direction and the lateral direction. In the bellophram 150, the center portion 152 is fixed to the pressure receiving surface 142 of the piston 140, and the flange portion 153 is fixed by the flange holding portion 132 of the single acting pneumatic cylinder 130. Of the bellophram 150, an annular single taper surface 154 that is folded back from the flange portion 153 and extends toward the center portion 152 forms a single taper angle θp with an angle formed with the virtual line N along the axis AX. It is assumed to be an inclined surface.

The following two reasons can be given as the reason for adopting a substantially trapezoidal shape for the conventional bellophram 150.
(1) In the vacuum on-off valve 100 provided with the bellophram 150, the piston outer diameter dp on the outer peripheral surface of the piston 140 is smaller than the inner diameter of the single acting pneumatic cylinder 130 by the amount of the predetermined gap 145. One tapered surface 154 extends to the position of the top dead center of the piston 150 as the piston 150 is driven.
(2) In the vacuum on-off valve 100, when the valve is closed, the central portion 152 and the flange portion 153 of the bellophram 150 are positioned at substantially the same height, and the single taper surface 154 is, as shown in FIGS. In the gap 145 between the piston 140 and the single-acting pneumatic cylinder 130, it is folded back into a mountain fold.
From these facts, the single tapered surface 154 is formed into a single inclined surface inclined at a predetermined single taper angle θp with respect to the axis AX along the stroke direction of the piston 150, that is, the imaginary line N. This is because 150 easily expands and contracts with the opening / closing operation of the vacuum opening / closing valve 100.

On the other hand, the vacuum on-off valve driven by the bellophram is disclosed in FIG. 1 of Patent Document 2 and FIGS. 2, 5, and 6 of Patent Document 3. Further, the fact that the belofram has inclined surfaces having different angles is disclosed in FIGS. 1 and 4 of Patent Document 4, FIG. 3 of Patent Document 5, and FIGS. 2 and 5 of Patent Document 6. ing.
Further, Patent Document 7 and Patent Document 8 disclose that a belofram is formed by insert molding a tricot weave base fabric.

Japanese Unexamined Patent Publication No. 9-72458 JP 2002-132354 A JP 07-150623 A JP 56-049462 Japanese Utility Model Publication No. 61-140296 Japanese Utility Model Publication No. 60-055466 Japanese Patent Laid-Open No. 10-317262 Japanese Patent Laid-Open No. 10-132077

However, the vacuum on-off valve 100 has the following problems.
(1) FIG.11 and FIG.12 is a position of the state which the vacuum on-off valve closed. In this state, when driving air is supplied to the air accommodating chamber AS, the pressure applied by the driving air is folded back in the central portion 152 of the bellophram 150 and the gap 145 between the piston 140 and the single acting pneumatic cylinder 130. The piston 140 is raised over the single tapered surface 154.
At this time, the single taper surface 154 has a single taper surface 154 partially separated from the outer peripheral surface of the piston 140 from the mountain-folded form shown in FIG. 12 by supplying driving air into the air accommodating chamber AS. It becomes the form which swelled toward the internal peripheral surface of the dynamic-pneumatic cylinder 130 (refer FIG. 15).
Since the shape of the bellophram 150 is substantially trapezoidal, and the single single tapered surface 154 is located on the outer side in the radial direction of the axis AX with respect to the outer peripheral surface of the piston 140, at the same position in the axis AX direction of the bellophram 150, The taper surface diameter length Dp of the surface in contact with the piston 140 of the belofram 150 in the radial direction is larger than the piston outer peripheral diameter dp as shown by a two-dot chain line in FIG. Although the bellophram 150 has a tapered surface, the piston 140 has a cylindrical shape, and therefore, the shortest diameter of the bellophram 150 must be matched to the diameter of the piston 140. Therefore, the position of πDp and πdp at the position shown in FIG. The difference will increase.
That is, the circumferential length (single taper circumferential length) πDp of the single taper surface 154 is longer than the circumferential length (piston outer circumferential surface circumference) πdp of the outer circumferential surface of the piston 140. A portion of 150 that does not contact the outer peripheral surface of the piston 140 is generated as a wrinkle generating portion 159.

The wrinkle generating portion 159 becomes larger as the difference in the circumferential length between the single taper surface circumferential length πDp and the piston outer circumferential surface circumferential length πdp increases. In addition, the pressure applied to the outer peripheral surface of the piston 140 along the single tapered surface 154 of the belofram 150 is within the internal space between the single tapered surface 154 and the outer peripheral surface of the piston 140 in the wrinkle generating portion 159. Greater than the pressure.
For this reason, in the wrinkle generating part 159, when a pressing force is applied along the single taper surface 154, a part of the single taper surface 154 is pressed by the pressing force so as to overlap or approach each other. The piston 140 extends from the vicinity of the outer peripheral surface of the piston 140 toward the outer side in the radial direction of the piston 140, and is folded in a state of being deeply bent at the outermost bending portion 159B in the radial direction. When the single taper surface 154 extends long outward in the radial direction, the single taper surface 154 tends to be bent at an acute angle in the bent portion 159B of the generated wrinkle generating portion 159, and the bent portion 159B is excessively bent. Bending stress may be applied.

As shown in FIG. 16, when the piston 140 shown in FIG. 15 rises in a state where the bent portion 159 </ b> B is formed, the single-action pneumatic cylinder 130 is moved from the side where the bent portion 159 </ b> B shown in FIG. It moves to the side that contacts the inner wall surface. The bent portion 159B is turned 180 degrees by this movement. Since the inner wall surface of the bending portion 159B has a sufficiently large inner diameter on the inner wall surface side of the single-acting pneumatic cylinder 130, the bending portion 159B is free from bending. However, when the bent portion 159B is turned 180 degrees, the bent portion 159B receives concentrated stress. Each time the vacuum opening / closing valve is driven, this concentrated stress is repeatedly received, and therefore, a longitudinal crack is generated in the belofram 150.
Although the present applicant sells the vacuum on-off valve according to the present invention all over the world, there is a problem with the durability of the belofram 150, but it is difficult to investigate the cause. The cause was investigated through repeated experiments.

(2) Further, the base fabric of the belofram 150 is a plain weave mesh as shown in FIG. 14, and the flexibility in the mesh direction is low and the belofram 150 itself is not easily bent. Are locally present as relatively large wrinkles on the periphery of the single tapered surface 154 (see FIG. 16). Then, when the valve is closed, the base fabrics of the single tapered surface 154 that are folded in the wrinkle generating portion 159 rub against each other, and cracks from the top portion 158 grow to the wrinkle generating portion 159 over time, and 150 base fabrics are torn.

  Due to the problems (1) and (2), there is a problem that the driving air supplied into the air storage chamber AS leaks through the bellophram 150 and the opening degree of the vacuum on-off valve 100 cannot be controlled. For this reason, the bellophram 150 must be frequently replaced, and a durable vacuum on-off valve has been demanded.

  The present invention has been made to solve such a problem, and the gap between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder is sealed with a bellophram that follows the operation of the piston, and the piston is sealed by the fluid. An object of the present invention is to provide a durable vacuum on-off valve that is driven to open and close.

In order to solve the above problems, the vacuum on-off valve of the present invention has the following configuration.
(1) A vacuum on-off valve that is connected between a vacuum vessel and a vacuum pump and controls the vacuum pressure in the vacuum vessel by changing the opening of the valve body with respect to the valve seat, A vacuum on-off valve that opens and closes a predetermined gap with the inner peripheral surface of the cylinder by a bellophram that follows the piston operation and that is driven by fluid to open and close the inner peripheral surface that contacts the piston of the bellophram When the valve body is in a position where it comes into contact with the valve seat, the outer peripheral surface of the piston is in contact with the valve seat. The inner peripheral diameter of the piston and the outer peripheral diameter of the piston are equal.
(2) In the vacuum on-off valve described in (1), the first inclination angle and the second inclination angle are equal.

(3) In the vacuum on-off valve described in (1) or (1), the belofram includes two inclined surfaces having different angles with respect to the axis along the stroke direction of the piston in the cross-sectional shape of the central cross section. And an inclination angle of an inclined surface having a small angle among the inclined surfaces is the first inclination angle.
(4) In the vacuum on-off valve according to (3), the belofram has a fixing portion that is fixed to the cylinder at a peripheral edge in a radial direction, and the inflection portion that connects the tapered surfaces is the axis of the belofram. It is characterized in that it is located closer to the fixed part than the center of the direction.
(5) In any one of the vacuum on-off valves described in (1) to (4), the bellophram is fitted to an outer periphery of a rod that connects the valve body and the piston, thereby A fitting hole for positioning is provided.

(6) In any one of the vacuum on-off valves according to (1) to (5), the belofram is a rubber having a base fabric having a flexible weave in a direction along the surface of the beloram. It is characterized by comprising a rubber molded member formed by insert molding.
(7) The vacuum on-off valve according to (6), wherein the weave of the base fabric is a tricot weave.
(8) In the vacuum on-off valve according to any one of (1) to (7), the belofram has a convex portion protruding in a thickness direction at a radial center portion, and the piston is It has a recess recessed in the pressure receiving surface in the bore direction, and the belofram and the piston are positioned and fixed on a concentric shaft by fitting the protrusion and the recess. And

(1) A vacuum on-off valve that is connected between a vacuum vessel and a vacuum pump and controls the vacuum pressure in the vacuum vessel by changing the degree of opening of the valve body with respect to the valve seat. A vacuum opening / closing valve that seals a predetermined gap with the inner peripheral surface of the inner peripheral surface with a bellophram that follows the operation of the piston, and opens and closes by driving the piston with a fluid, and the inner peripheral surface that contacts the piston of the bellophram is predetermined It is formed at the first inclination angle, the outer peripheral surface of the piston is formed at a predetermined second inclination angle, and when the valve body is in a position where it contacts the valve seat, Since the inner diameter of the piston is equal to the outer diameter of the piston, when the vacuum on-off valve is closed and driving air is put into the cylinder and air pressure is applied to the bellophram, Circumference and fixie For the outer peripheral diameter equal, never bent bellofram at all occurs.
Conventionally, since the piston has a cylindrical shape, the inner peripheral diameter that contacts the piston of the bellophram at a position corresponding to the piston end face has to be made larger than the outer peripheral diameter of the piston. In the present invention, by providing an inclined surface on the outer periphery of the piston, it becomes possible for the first time to make the inner diameter of the bellophram and the outer diameter of the piston the same length at the position where the vacuum on-off valve is closed.

(2) Since the first inclination angle of the bellophram and the second inclination angle of the piston are made equal, even when the piston moves a certain distance, the inner circumference diameter of the bellophram and the outer diameter of the piston are the same. Since it becomes equal, the belofram does not bend. Even if the first inclination angle is slightly larger than the second inclination angle, if the inner peripheral diameter of the bellophram in contact with the piston and the outer diameter of the piston are equal when the valve body is in a position in contact with the valve seat, The present applicant has confirmed through experiments that the durability of the battery is greatly improved. The present applicant has confirmed through experiments that the durability is further improved if the first inclination angle and the second inclination angle are made equal.

In the vacuum on-off valve according to the present invention described in (3), the belofram has at least two tapered surfaces having different angles with respect to the axis along the stroke direction of the piston in the cross-sectional shape when viewed from the bore direction of the piston. For example, when there are two tapered surfaces, the first taper angle θ1 is set to be larger than the single taper angle θp in the conventional belofram (θp <θ1). Thus, the second taper angle θ2 can be made smaller than the single taper angle θp (θ2 <θp).
In this case, the first taper surface inclined at the first taper angle θ1 with respect to the axis is on the inner peripheral surface side of the cylinder, and the second taper surface inclined at the second taper angle θ2 with respect to the axis is the outer periphery of the piston. By forming the bellophram in a form positioned on the surface side, in particular, the inclination angle of the second tapered surface of the bellophram can be made equal to the inclination angle of the tapered surface of the outer peripheral surface of the piston.
Accordingly, since the belofram has at least two tapered surfaces with different angles, the elasticity of the vacuum on-off valve can be maintained, and the belofram can be shortened due to cracks caused by wrinkles. It is possible to suppress damage.

By the way, when the vacuum opening / closing valve is opened or closed, when the taper surface of the belofram is folded back into a mountain fold, the taper surface of the portion where the taper surface is folded back is the top dead center of the piston as the piston is driven. Located near the center of the stroke direction when extended to the position of the point or bottom dead center.
In the vacuum on-off valve of the present invention described in (4), the inflection part that connects the tapered surfaces is located on the fixed part side from the center position in the axial direction of the bellophram, so that the taper surface of the bellophram is folded back into a mountain fold shape. Even if it is, it will not be folded at the inflection part.
Even if the vacuum open / close valve is repeatedly opened and closed, it is not repeatedly folded at the inflection portion where stress is more concentrated than the other portions of the tapered surface of the belofram. It is possible to prevent the occurrence of degradation of the resulting belofram (fatigue of the material constituting the belofram).
Therefore, early damage to belofram can be suppressed.

In the vacuum on-off valve described in (5), the bellophram includes a fitting hole for positioning the bellophram by fitting with an outer periphery of a rod connecting the valve body and the piston.
Thereby, positioning of a piston and a bellophram can be correctly performed via a rod.

Further, in the vacuum on-off valve of the present invention described in (6), the belofram is made of a rubber molded member obtained by insert-molding a base fabric having a texture that is flexible in a direction along the surface of the belofram.
Accordingly, the bellowram can be easily bent according to the operation of the piston and the shape of the piston while maintaining the airtightness with rubber and the strength against the pressure of the fluid with the base cloth.

Further, in the vacuum on-off valve according to the present invention described in (7), since the weave of the base fabric in the bellophram is a tricot weave, the bellophram can freely correspond to the operation of the piston and the shape of the piston when the fluid is pressurized. It becomes easy to bend.
In particular, in the vacuum on-off valve of the present invention, when the taper surface of the bellophram swells to the outer peripheral surface side of the piston when the fluid is pressurized, the bellophram is easily bent along the shape of the outer peripheral surface of the piston.
For this reason, in the bellowram of the vacuum on-off valve of the present invention, the wrinkles generated on the tapered surface are caused by the difference between the circumferential length of the tapered surface and the circumferential length of the outer circumferential surface of the piston at an arbitrary position in the piston stroke direction. Can be made smaller than that of the conventional vacuum opening / closing valve. Moreover, this wrinkle does not exist as a relatively large wrinkle locally on the periphery of the single tapered surface of the belofram, unlike the belofram of the conventional vacuum on-off valve, and is smaller than the wrinkle generated in the conventional belofram. Suppressed and scattered over the circumference of the tapered surface. For this reason, when opening or closing the vacuum on-off valve, it is easy to avoid contact between the tapered surfaces that are folded at the wrinkled portion, and the occurrence of friction between the base fabrics is suppressed. can do.
Therefore, even if a crack occurs in the mountain-folded portion of the taper surface, the growth of this crack suppresses damage to belofram caused by rubbing between the base fabrics of the mountain-folded taper surface. Can do.
The tricot weave is similar to, for example, a knot weave, which is a yarn weaving in a form in which peaks and valleys are alternately arranged in a predetermined direction like a kite, or a knit weave. This is a weaving method in which the woven fabric has flexibility, elasticity and elasticity.

Further, in the vacuum on-off valve of the present invention described in (8), the belofram has a convex portion protruding in the thickness direction at the radial center portion, and the piston is recessed in the pressure receiving surface in the bore direction. The bellophram and the piston are positioned and fixed on the concentric shaft by fitting the convex portion and the concave portion.
As a result, there is no relative displacement between the center portion of the bellowram in the radial direction and the pressure receiving surface of the piston. Therefore, the taper surface of the bellophram is bent evenly in the circumferential direction of the taper surface in accordance with the operation of the piston. It can stretch. For this reason, a piston can be driven appropriately.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying a vacuum on-off valve according to the present invention will be described below in detail with reference to the drawings. FIG. 9 is a schematic diagram showing a configuration of the configuration vacuum pressure control system 1 in which the vacuum on-off valve 10 is used.
The vacuum pressure control system 1 is a vacuum pressure control system that alternately supplies and exhausts process gas and barge gas into the vacuum chamber 2 in which the wafer 8 is arranged when the wafer 8 is surface-treated in the semiconductor manufacturing process. As shown in FIG. 9, the vacuum pressure control system 1 includes a vacuum chamber 2 (vacuum container), a vacuum pump 5, an air supply source 6 for supplying driving air AR, a vacuum on-off valve 10, and a valve of the vacuum on-off valve 10. It comprises a servo valve (not shown) for controlling the opening VL, a vacuum pressure control device 7 and the like electrically connected to the vacuum on-off valve 10 and the like.
A gas supply port 2 a of the vacuum chamber 2 includes a process gas supply source used for surface treatment of the wafer 8 disposed in the vacuum chamber 2 and a nitrogen gas used for purging the process gas in the vacuum chamber 2. Are connected in parallel with the source.
On the other hand, a vacuum on-off valve 10 and a chamber pressure sensor 3 are connected in parallel to the gas exhaust port 2 b of the vacuum chamber 2 via a shut-off valve 4. The chamber pressure sensor 3 is electrically connected to the vacuum pressure control device 7 and measures the vacuum pressure of the process gas or the like in the vacuum chamber 2. The vacuum on-off valve 10 is also connected to the vacuum pump 5.

The vacuum on-off valve 10 will be described with reference to FIGS.
FIG. 1 is an explanatory diagram showing a cross-sectional view of the belofram 50 configured in the vacuum on-off valve 10 of the present embodiment when viewed from the bore direction BR of the piston 40. FIG. 2 is an explanatory diagram for explaining the configuration of the rubber molding member 51 constituting the belofram 50, and is a cross-sectional view showing the inside of the one-dot chain line in FIG. FIG. 3 is an explanatory view for explaining the texture of the base fabric 51B in the rubber molded member 51 shown in FIG. FIG. 4 is an explanatory diagram for explaining the configuration of the vacuum on-off valve 10 and shows a closed state. FIG. 5 is a view showing a valve open state of the vacuum on-off valve 10 shown in FIG. FIG. 6 is an enlarged view of a portion P in FIG.
The vacuum on-off valve 10 of the present embodiment changes the valve opening VL by the drive air AR supplied from the air supply source 6 into the air accommodating chamber AS through a servo valve (not shown), and thereby the process gas in the vacuum chamber 2 is changed. It is used as a vacuum on-off valve for controlling the vacuum pressure of the like.
The vacuum opening / closing valve 10 is open on the axis AX direction, that is, in the valve shift direction (vertical direction in FIGS. 4 and 5) in which the poppet valve body 76 opens and closes (upward in FIGS. 4 and 5). And a bellows type poppet valve portion 70 located on the valve closing side (downward in FIGS. 4 and 5).

The pilot cylinder portion 20 further includes a single-acting pneumatic cylinder 30, a cylinder support portion 32, an air accommodating chamber AS, a piston 40, a return spring 47, a bellowram 50, and the like.
In the vacuum on-off valve 10, when the driving air AR is supplied to the air accommodating chamber AS, the piston 40 is not in contact with the inner peripheral surface 31 of the single-acting pneumatic cylinder 30, and the stroke direction ST along the axis AX direction. To drive. The piston outer peripheral diameter dp of the outer peripheral surface 41 of the piston 40 is smaller than the diameter of the cylinder inner peripheral surface 31 of the single-acting pneumatic cylinder 30 by a predetermined size. An annular recess 44 is formed in the pressure receiving surface 43 of the piston 40 in the stroke direction ST. A predetermined gap 45 between the outer peripheral surface 41 of the piston 40 and the cylinder inner peripheral surface 31 of the single-acting pneumatic cylinder 30 is sealed by a bellophram 50 shown in FIG. Airtightness within the AS is ensured.
Since the piston 40 is driven in a non-contact manner with the cylinder inner peripheral surface 31 of the single-acting pneumatic cylinder 30, no stick slip of the piston 40 occurs, and the piston 40 is single-acting with high responsiveness and accurate positional accuracy. The inside of the pneumatic cylinder 30 can be driven.

The piston 40 is biased toward the valve closing side in the valve shift direction by a return spring 47. When the drive air AR is not supplied to the air accommodating chamber AS, the piston 40 is located at the bottom dead center by the urging force of the return spring 47 (see FIG. 4). On the other hand, when the drive air AR is supplied to the air accommodating chamber AS, the piston 40 moves to the valve opening side in the valve shift direction against the urging force of the return spring 47 (see FIG. 5).
Further, the vacuum on-off valve 10 includes a displacement amount of the piston 40 corresponding to the displacement of the piston 40 from the bottom dead center position toward the top dead center when the piston 40 moves in the valve shift direction, that is, the vacuum on-off valve 10. A displacement sensor 81 that measures the valve opening degree VL in a non-contact manner is provided (see FIGS. 4 and 5). The displacement sensor 81 is electrically connected to the vacuum pressure control device 7.

The bellophram 50 is a bellophram composed of a rubber molded member 51 in which a base fabric 51B having a tricot weave shown in FIG. 3 is inserted into a rubber 51A (see FIGS. 1 and 2). In addition, as shown in FIG. 3, tricot weave refers to, for example, cocoon weaving, which is a weave of yarn in a form in which mountain portions and valley portions are alternately arranged in a predetermined direction like a cocoon. It is a weave of the same form as the knit of the knitted fabric, etc., and is a weave that gives the fabric flexibility, elasticity and stretchability.
When the driving air AR is supplied into the air accommodating chamber AS, the bellophram 50 can be expanded and contracted so as to keep the effective pressure receiving area on the pressure receiving surface 43 of the piston 40 constant. The bellophram 50 is configured by the rubber molding member 51 so that the base fabric 51B has strength against the pressure applied by the driving air AR supplied to the air accommodating chamber AS, and the rubber 51A has airtightness. Yes. Examples of the rubber 51A used for the rubber molded member 51 include natural rubber, acrylonitrile-butadiene rubber, styrene-butadiene rubber, butadiene rubber, isoprene rubber, propylene-butadiene rubber, acrylonitrile-isoprene rubber, chloroprene rubber, and butyl rubber. And synthetic rubbers such as ethylene-propylene rubber, acrylic rubber, fluorine rubber, ether-thioether rubber, polysulfide rubber, urethane rubber, and silicon rubber. Further, as the base fabric 51B, for example, polyamide (6 nylon, 66 nylon, etc.), aramid, polyester, cotton, or the like is used as a tricot weave, and the surface 51a of the belofram 50 (rubber molded member 51), What weaved with the weave which has flexibility in the direction along 51b is mentioned.

In the present embodiment, as shown in FIG. 1, the bellophram 50 has a cross-sectional shape when viewed from the bore direction BR of the piston 40 (left and right direction in FIGS. 4 and 5), and the stroke direction ST direction of the piston 40 ( In FIG. 4 and FIG. 5, two first tapered surfaces 55 </ b> A and second tapered surfaces 55 </ b> B having different angles with the axis AX along the vertical direction) are provided. Further, the bellophram 50 includes an annular flange portion 54 (fixed portion) located on the outer peripheral edge in the radial direction (bore direction BR of the piston 40), and the first and second tapered surfaces between the flange portion 54 and the flange portion 54. It has a central portion 52 (radial central portion) located at the radial center with 55A and 55B in between.
The first taper surface 55A is an inclined surface that is turned back from the inclination starting point portion 54S on the radially inner side of the flange portion 54, and an angle formed by the virtual line M parallel to the axis AX is a first inclination angle θ1 (0 <θ1 < 90 degrees). The second taper surface 55B is an annular inclined surface having a second inclination angle θ2 (0 <θ2 <θ1) as an angle formed with the virtual line M. The first taper surface 55A and the second taper surface 55B are continuously connected by an inflection portion 56. The inflection portion 56 is a central position in the axis AX direction of the bellophram 50 in the state shown in FIG. It is located on the flange 54 side. The reason why the inflection 56 is in such a position is that when the vacuum on-off valve 100 is closed, the second taper surface 55B of the bellophram 50 moves to the position of the top dead center. This is because the second taper surface 55B is folded back into a mountain fold at a position near the center of the stroke direction ST when the second tapered surface 55B extends to the position of the top dead center of the piston.
Further, the central portion 52 is continuously connected from the second tapered surface 55B in a direction along the bore direction BR of the piston 40 (the left-right direction in FIGS. 4 and 5). A through hole 57 through which a piston rod 48 (described later) is inserted is drilled in the central portion 52, and a convex portion 53 protruding in the thickness direction (vertical direction in FIG. 1) of the central portion 52 is formed in the through hole 57. A ring is provided around the periphery. The size of the through hole 57 is formed with high accuracy so as to fit the outer periphery of the rod 47.

As shown in FIG. 6, the bellophram 50 is positioned with the piston 40 by fitting the convex portion 53 into the concave portion 44 of the piston 40. The bellophram 50 is sandwiched between the piston 40 and the plate-shaped fixture 46 with the central portion 52 in contact with the pressure receiving surface 42 of the piston 40, and the piston 40 and the fixture 46 are sandwiched between the piston 40 and the fixture 46. It is fixed by screw connection.
Further, the flange portion 54 of the bellophram 50 is fixed by being sandwiched between the single-acting pneumatic cylinder 30 and the cylinder support portion 32 by the flange holding portion 32.

In the vacuum on-off valve 10, when the piston 40 is at the bottom dead center position, that is, when the driving air AR is not supplied to the air accommodating chamber AS, the flange portion 54 and the central portion 52 of the bellowram 50 are in the stroke direction ST. The positions are almost the same (see FIG. 4). Then, as shown in FIGS. 4, 6, and 7, the second tapered surface 55 </ b> B is folded back into a mountain fold shape at the top 58 in the gap 45 between the piston 40 and the cylinder 30.
On the other hand, when the driving air AR is supplied to the air storage chamber AS, the second tapered surface 55B is folded in the top 58 as shown in FIG. 6 and FIG. As shown, the top dead center side in the stroke direction ST direction of the piston 40 (in FIG. 6 and FIG. 7, upward) while expanding along the cylinder inner peripheral surface 31 of the single-acting pneumatic cylinder 30 and the outer peripheral surface 41 of the piston 40. ) Toward the state shown in FIG.
In this manner, the bellophram 50 has the first and second tapered surfaces 55A and 55B connected to the piston 40 in a state where the flange portion 54 is fixed to the flange holding portion 32 and the center portion 52 is fixed to the pressure receiving surface 42 of the piston 40, respectively. The gap 45 is sealed while being folded or extended following the driving of the piston 40 by being positioned in the gap 45 with the cylinder 30.

FIG. 6 is a partially enlarged view of FIG. 4, and FIG. 4 shows a valve closed state in which the O-ring 79 completely contacts the valve seat 73. Therefore, FIG. 7 shows the shape of the bellophram 50 in the valve closed state.
When the driving air AR is supplied in the valve closed state in which the O-ring 79 is completely in contact with the valve seat 73, the belofram 50 is positioned as shown by a two-dot chain line in FIG. The point of contact changes slightly. In the present invention, the inner peripheral diameter of the bellophram 50 at the position where the bellophram 50 contacts the piston 40 (the position indicated by the height L1, that is, the top position where the bellophram 50 indicated by the two-dot chain line in FIG. 7 contacts the piston 40). Is W2.
On the other hand, a sectional view of the piston 40 is shown in FIG. The outer shape of the piston 40 forms a tapered piston taper surface 40a having a tip portion having an angle θ. This angle θ is equal to the second taper angle θ2 of the bellophram 50. The piston taper surface 40a is formed about the lower half of the whole. The upper half does not need to be tapered because it does not come into contact with the belofram 50.

That is, W1 is the outer diameter of the piston at the upper end where the outer periphery of the piston is in contact with the bellowram 50 when the driving air AR is supplied in the valve closed state where the O-ring 97 is in contact with the valve seat 73. is there.
W2 is in contact with the piston 40 of the bellowram 50 at the upper end where the bellowram 50 is in contact with the piston 40 when the driving air AR is supplied in the valve closed state where the O-ring 97 is in contact with the valve seat 73. It is the inner circumference.
As shown in FIG. 7, the outer peripheral diameter of the piston 40 at the position of the distance L1 from the piston tip is W1. The distance L1 from the tip of the piston is the upper end position where the bellophram 50 is in contact with the piston 40 in the bellophram 50 shown by a two-dot chain line in FIG.
Here, in the valve closed state shown in FIG. 4, W2 of the bellophram 50 and W1 of the piston 40 are set to be equal in length.

Next, the bellows type poppet valve unit 70 will be described.
The bellows poppet valve section 70 includes a valve body 71, a bellows 75, a poppet valve body 76, an O-ring holding member 77, an O-ring 79, and the like.
A piston rod 48 is connected to the central portion in the radial direction of the piston 40, and the piston rod 48 and the piston 40 are sealed with an O-ring 49. The piston rod 48 extends toward the bellows type poppet valve portion 70 and is connected to the poppet valve body 76 at the valve opening side end of the piston rod 48. The poppet valve body 76 is connected to the stroke direction ST of the piston 40. As the valve is driven, it moves together with the piston 40 in the valve shift direction. The bellows 75 is configured to fix an end portion on one end side in the axis AX direction (upward in FIGS. 4 and 5) and attach the other end side to the poppet valve body 76 to cover the radially outer side of the piston rod 48. Thus, the poppet valve body 76 is attached so as to expand and contract with the drive in the valve shift direction.

The poppet valve body 76 and the O-ring holding member 77 are fixed on the valve closing side (downward in FIGS. 4 and 5) of the poppet valve body 76 and are formed by the poppet valve body 76 and the O-ring holding member 77. The O-ring mounting portion 78 is provided. The O-ring 79 is disposed in the O-ring attachment portion 78 and can contact the valve seat 73 of the valve main body 71. The valve body 71 has a first port 72 connected to the vacuum pump 5 and a second port 74 connected to the gas exhaust port 2 b of the vacuum chamber 2.
In the vacuum on-off valve 10, when the driving air AR is not supplied to the air accommodating chamber AS, the piston 40 is positioned at the bottom dead center due to the urging force of the return spring 47, so that the poppet valve body 76 connected to the piston 40 is O The valve seat 73 is pressed through the ring 79. Accordingly, the first port 72 is closed by the poppet valve body 76, and the vacuum on-off valve 10 is closed (valve opening VL = 0).
On the other hand, when the driving air AR is supplied to the air accommodating chamber AS, the piston 40 moves to the valve opening side in the valve shift direction against the urging force of the return spring 47. 76 also moves to the valve opening side and leaves the valve seat 73. As a result, the vacuum on-off valve 10 is opened (valve opening VL> 0), and the first port 72 and the second port communicate with each other. When the vacuum opening / closing valve 10 is opened, the vacuum pump 5 can suck the process gas or nitrogen gas in the vacuum chamber 2.

In the vacuum on-off valve 10 of the present embodiment, the bellophram 50 includes a first taper surface 55A whose angle with the axis AX is a first inclination angle θ1 in a cross-sectional shape when viewed from the bore direction BR of the piston 40, and The second tapered surface 55B having the second inclination angle θ2 is provided.
Here, for the first and second taper angles θ1 and θ2 between the imaginary line M along the axis AX and the first and second taper surfaces 55A and 55B in the bellophram 50, the bellophram of the vacuum on-off valve 10 of the present embodiment is used. 50 and the Bellofram 150 of the conventional vacuum on-off valve 100 will be compared.
In the vacuum on-off valve 10, as described above, the angle formed between the first tapered surface 55A and the axis AX (virtual line M) is the first taper angle θ1 (0 <θ1 <90 °). Further, since the angle formed between the second taper surface 55B and the axis AX (imaginary line M) is the second taper angle θ2 (0 <θ2 <θ1), the second taper surface 55B has an arbitrary direction along the axis AX. The radial length at the position is the second tapered surface diameter D2, and the circumferential length at this position is the second tapered surface circumferential length πD2.
On the other hand, in the conventional vacuum on-off valve 100, since the single tapered surface 154 of the bellophram 150 is single, the angle formed by the single taper surface 154 and the virtual line N along the axis AX of the bellophram 150 is a single taper. The angle θp (0 <θp <90 °) (see FIG. 14). Thereby, in the single taper surface 154, the length in the radial direction at an arbitrary position in the stroke direction of the piston is the single taper surface diameter length Dp, and the length in the circumferential direction at this position is the single taper surface circumferential length πDp. (See FIG. 16).

In the vacuum on-off valve 10 of the present embodiment, the second taper angle θ2 is smaller than the single taper angle θp (θ2) by making the first taper angle θ1 larger than the single taper angle θp (θp <θ1). <Θp). That is, for the magnitudes of the first taper angle θ1, the second taper angle θ2, and the single taper angle θp, the relationship of θ2 <θp <θ1 (1) holds. Based on this equation (1), the bellophram 50 of the vacuum on-off valve 10 has a first taper surface 55A inclined at a first taper angle θ1 with respect to the axis AX on the cylinder inner peripheral surface 31 side of the single acting pneumatic cylinder 30. In addition, the second taper surface 55B inclined at the second taper angle θ2 with respect to the axis AX is formed on the outer peripheral surface 41 side of the piston 40, respectively.
On the other hand, the piston taper surface 40a of the piston 40 is formed at the same inclination angle as the second taper surface 55B of the bellophram 50. As shown in FIG. 7, when the driving air AR is supplied in the valve closed state in which the O-ring 79 is completely in contact with the valve seat 73, the position of the bellowram 50 is indicated by a two-dot chain line in FIG. Become. At that time, at the upper end where the bellophram 50 and the piston 40 contact, the inner peripheral diameter W2 of the bellophram 50 that contacts the piston 40 and the outer peripheral diameter W1 of the piston 40 that contacts the bellophram 50 are equal. As shown in FIG. 9, the belofram 50 and the piston 40 are in close contact with each other, and no bending occurs.
Thereafter, the point at which the bellophram 50 comes into contact with the piston 40 changes. However, since the piston taper surface 40a of the piston 40 is formed at the same inclination angle as the second taper surface 55B of the bellophram 50, The state where the piston 40 is in close contact is maintained.

  Since such a wrinkle generating portion 59 does not occur at all as compared with the wrinkle generating portion 159 generated in the conventional bellophram 150, stress concentration does not occur when the piston 40 moves, and it is repeated many times. However, no crack can occur in the direction of movement of the piston 40 as in the prior art. Although the present applicant confirmed by the repeated test, it confirmed that the crack like the past did not generate | occur | produce at all even if it experimented the repetition frequency of the several dozen times of the past.

As described above in detail, according to the vacuum on-off valve of the present embodiment, the opening degree of the O-ring 79 which is connected between the vacuum vessel 2 and the vacuum pump 5 and is a valve body with respect to the valve seat 73. Is a vacuum on-off valve 10 that controls the vacuum pressure in the vacuum vessel 2 and follows a predetermined gap between the outer peripheral surface of the piston 40 and the inner peripheral surface 31 of the cylinder 30 along with the operation of the piston 40. 50 is a vacuum opening / closing valve 10 that is opened and closed by driving the piston 40 with fluid, and that the belofram 50 is formed at a predetermined inclination angle θ2, and the outer periphery of the piston 40 is at a predetermined inclination angle θ. The inner diameter of the bellophram that contacts the piston and the outer diameter of the piston are equal when the valve body is in a position in contact with the valve seat. In the closed state When driving air is put into the cylinder and the air pressure is applied to the bellophram, the inner diameter of the bellophram is equal to the outer diameter of the piston, so that no bending occurs in the bellophram.
Conventionally, since the piston has a cylindrical shape, the inner peripheral diameter that contacts the piston of the bellophram at a position corresponding to the piston end face has to be made larger than the outer peripheral diameter of the piston. In the present invention, by providing an inclined surface on the outer periphery of the piston, it becomes possible for the first time to make the inner diameter of the bellophram and the outer diameter of the piston the same length at the position where the vacuum on-off valve is closed.

In addition, since the first inclination angle θ2 of the inner peripheral surface that contacts the piston 40 of the bellophram 40 and the second inclination angle θ of the piston 40 are equal, even when the piston 40 moves a certain distance, Since the inner peripheral diameter of the bellophram 40 that contacts the piston 40 is equal to the outer diameter of the piston 40, the bellophram 50 is not bent.
Even if the first inclination angle θ2 is slightly larger than the second inclination angle θ, the inner peripheral diameter of the bellophram 50 that contacts the piston 40 when the O-ring 97 that is the valve body is in a position that contacts the valve seat 73; The present applicant has confirmed through experiments that the durability of the belofram 50 is significantly improved if the outer diameters of the pistons 40 are equal. The present applicant has confirmed through experiments that the durability is further improved by making the first inclination angle θ2 and the second inclination angle θ equal.

In addition, since the bellophram 50 has two of the first tapered surface 55A and the second tapered surface 55B, it can maintain the stretchability associated with the opening / closing operation of the vacuum on-off valve 10 and is caused by wrinkles. It is possible to suppress the belofram 50 from being damaged in a short time due to the generated crack.
In the vacuum on-off valve 10, the inflection portion 56 that connects the first taper surface 55 </ b> A and the second taper surface 55 </ b> B is located closer to the flange portion 54 than the center position of the axis AX in the bellowram 50. Even when the second tapered surface 55 </ b> B is folded back in a mountain fold shape, it is not folded back at the inflection portion 56.
Even when the vacuum opening / closing valve 10 is repeatedly opened and closed, the second tapered surface 55B of the first and second tapered surfaces 55A and 55B of the belofram 50 has an inflection portion 56 where stress is more concentrated than the other portions. Since the folding is not repeatedly performed, it is possible to prevent the deterioration of the belofram 50 (the material fatigue of the rubber molding member 51) due to the repeated folding at the inflection portion 56.
Therefore, it is possible to prevent the belofram 50 from being damaged early.

Further, in the vacuum on-off valve 10 of the present embodiment, the bellophram 50 is fitted to the outer periphery of the rod 48 that connects the poppet valve body 76 that holds the O-ring 79 that is the valve body and the piston 40, so that Since the fitting hole 57 for positioning the valve 50 with respect to the piston 40 is provided, the belofram 50 can be positioned on the piston 40 easily and accurately.
Further, in the vacuum on-off valve 10, the bellophram 50 is a rubber molded member in which a base fabric 51B having a flexible tricot weave in the direction along the surface 51a of the bellophram 50 is embedded in the rubber 51A by insert molding. 51.
Accordingly, the rubber 51A has airtightness and the strength against the pressing force of the driving air AR is held by the base fabric 51B, and the belofram is easily bent according to the operation of the piston 40 and the shape of the outer peripheral surface 41 of the piston 40. 50.
In particular, in the vacuum on-off valve 10 of the present embodiment, the weave of the base fabric 51B in the bellophram 50 is a tricot weave. Therefore, the second tapered surface 55B of the bellophram 50 is formed on the outer peripheral surface 41 of the piston 40 when the driving air AR is supplied. When swelled along, the belofram 50 is easily bent along the shape of the outer peripheral surface 41 of the piston 40.
Further, in the vacuum on-off valve 10, the belofram 50 and the piston 40 are positioned and fixed on the concentric shaft by fitting the convex portion 53 and the concave portion 44.
Thereby, since the relative position shift of the center part 52 of the bellophram 50 and the pressure receiving surface 43 of the piston 40 does not occur, the first and second taper surfaces 55A and 55B of the bellophram 50 match the operation of the piston 40. The first and second tapered surfaces 55A and 55B can be bent and extended evenly in the circumferential direction. Therefore, the piston 40 can be driven appropriately, and the gap 45 between the outer peripheral surface 41 of the piston 40 and the cylinder inner peripheral surface 31 of the single-acting pneumatic cylinder 30 can be sealed in an appropriate state by the bellofram 50. .

In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof. .
For example, in the present embodiment, the concave portion 44 of the piston 40 is provided on the pressure-receiving surface 43, and the convex portion 53 of the bellophram 50 is provided on the central portion 52 in an annular form. However, the concave portion of the piston and the convex portion of the bellophram may be in a form in which both are positioned by fitting the concave portion of the piston and the convex portion of the bellophram. The form of the recess and the protrusion can be changed as appropriate.
In the present embodiment, in the bellophram 50, the first tapered surface 55A having an annular shape with the first inclined angle θ1 as the angle formed by the imaginary line M is defined between the inclined starting point portion 54S and the inflection portion 56. However, the surface shape between the fixed portion and the tapered surface of the bellophram may be an arc shape with a cross-sectional shape when viewed from the bore direction of the piston.

It is sectional drawing which shows the bellophram with which the vacuum on-off valve of this embodiment was comprised. It is explanatory drawing for demonstrating the rubber molding member which makes the bellofram of this embodiment. It is explanatory drawing explaining the weave of a base fabric among the beloframs of this embodiment. It is explanatory drawing explaining the structure of the vacuum on-off valve of this embodiment, and is a figure which shows a valve closing state. It is explanatory drawing explaining the structure of the vacuum on-off valve of this embodiment, and is a figure which shows a valve opening state. FIG. 5 is an enlarged view of a P portion in FIG. 4. FIG. 7 is a diagram illustrating a Q portion in FIG. 6, and is an explanatory diagram illustrating an enlarged state of a gap between an outer peripheral surface of a piston and an inner peripheral surface of a cylinder. 4 is a cross-sectional view showing the shape of a piston 40. FIG. It is AA arrow sectional drawing of FIG. 6, and is explanatory drawing for demonstrating the form of the belofram at the time of pressurization. It is explanatory drawing explaining the structure of the vacuum pressure control system which has a vacuum on-off valve of this embodiment. It is explanatory drawing explaining the structure of the conventional vacuum on-off valve. In FIG. 11, it is an enlarged view of the R section. It is sectional drawing which shows the conventional bellophram. It is explanatory drawing explaining the weave of a base fabric among the conventional beloframs. It is sectional drawing which shows the conventional bellophram, and is explanatory drawing for demonstrating the form of the bellophram at the time of pressurization. It is BB arrow sectional drawing of FIG.

Explanation of symbols

2 Vacuum chamber (vacuum container)
DESCRIPTION OF SYMBOLS 5 Vacuum pump 10 Vacuum on-off valve 31 Cylinder inner peripheral surface ST Stroke direction 41 Outer peripheral surface 43 Pressure receiving surface 44 Recess 45 Clearance 46 Fixing tool 50 Bello diaphragm (diaphragm)
51 Rubber molding member 51a, 51b Surface 51A Rubber 51
51B Base fabric 51
52 Center (radial center)
53 Convex part 54 Flange part 54S Inclination starting point part 56 Inflection part AR Drive air (fluid)
AX Axis line BR Bore direction W1 The outer diameter of the piston at the upper end where the outer periphery of the piston is in contact with the bellophram 50 when the driving air AR is supplied in the valve closed state where the O-ring 97 contacts the valve seat 73 When the driving air AR is supplied with the W2 O-ring 97 in contact with the valve seat 73, the bellophram 50 is in contact with the piston 40 of the bellophram 50 at the upper end where it is in contact with the piston 40. Inner diameter θ1 First taper angle θ2 Second taper angle

Japanese Unexamined Patent Publication No. 9-72458 JP 2002-132354 A JP 07-150623 A JP 56-049462 Japanese Utility Model Publication No. 61-140296 Japanese Utility Model Publication No. 61-172230 Japanese Patent Laid-Open No. 10-317262 Japanese Patent Laid-Open No. 10-132077

Claims (8)

A vacuum on-off valve connected between a vacuum vessel and a vacuum pump and controlling the vacuum pressure in the vacuum vessel by changing the opening of the valve body with respect to the valve seat, In a vacuum on-off valve that seals a predetermined gap with the peripheral surface with a bellophram that follows the operation of the piston, and opens and closes by driving the piston with fluid,
The inner peripheral surface of the bellophram that contacts the piston is formed at a predetermined first inclination angle;
The outer peripheral surface of the piston is formed at a predetermined second inclination angle;
When the valve body is in a position where it comes into contact with the valve seat, the inner peripheral diameter of the bellophram that contacts the piston is equal to the outer peripheral diameter of the piston;
A vacuum on-off valve characterized by In the vacuum on-off valve according to claim 1,
The vacuum on-off valve, wherein the first inclination angle and the second inclination angle are equal. In the vacuum on-off valve according to claim 1 or 2,
The belofram has two inclined surfaces having different angles with respect to an axis along the stroke direction of the piston in the cross-sectional shape of the central cross section;
Among the inclined surfaces, the inclination angle of the inclined surface with a small angle is the first inclination angle,
A vacuum on-off valve characterized by The vacuum on-off valve according to claim 3,
The belofram has a fixing portion to be fixed to the cylinder at a peripheral edge in a radial direction;
The inflection part connecting the inclined surfaces is located on the fixed part side from the position in the axial direction center in the belofram,
A vacuum on-off valve characterized by In any one of the vacuum on-off valves according to claim 1 to claim 4,
A vacuum on-off valve comprising a fitting hole for positioning the bellophram by fitting the bellophram to an outer periphery of a rod connecting the valve body and the piston. The vacuum on-off valve according to any one of claims 1 to 5,
2. The vacuum on-off valve according to claim 1, wherein the bellophram is made of a rubber molded member in which a base cloth having a flexible weave in the direction along the surface of the bellophram is insert-molded. The vacuum on-off valve according to claim 6,
A vacuum on-off valve, wherein the weave of the base fabric is a tricot weave. The vacuum on-off valve according to any one of claims 1 to 7,
The belofram has a convex portion projecting in the thickness direction in the radial center portion,
The piston has a recess recessed in the pressure receiving surface in the bore direction,
The vacuum on-off valve characterized in that the bellophram and the piston are positioned and fixed on a concentric shaft by fitting the convex portion and the concave portion.

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