JP2001012649A - Slow exhaust valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slow exhaust valve having no limitation for regulation of an exhaust amount and provide a slow exhaust valve with high concentric precision at a low cost. SOLUTION: This slow exhaust valve 1 comprises a valve seat 13 and a valve element 21 regularly energized to the valve seat 13 side within a valve body 10 having a pump port 11 and a chamber port 12. It further comprises a main spindle 25 the lower end of which is fixed to the valve element 21, a lower main piston 35 fixed to the main spindle 25 and an upper sub-piston 36 to which the main spindle 25 is slidably fitted and prevented from being slipped out from the upper end, both the pistons being located in the upper and lower part of the main spindle 25, and a cylinder tube 30 formed of one cylindrical body having an intermediate wall 30a for vertically partitioning a vertical pair of piston chambers 33, 34 wherein the main piston 35 and the auxiliary piston 36 are slid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slow exhaust valve for slowly and quickly exhausting a vacuum chamber of a semiconductor manufacturing apparatus, and more particularly to a slow exhaust valve having a structure which can be manufactured at low cost.

[0002]

2. Description of the Related Art When vacuum evacuation is performed in a vacuum chamber in a semiconductor manufacturing apparatus, a large amount of gas flows in a short time if the gas in the vacuum chamber is rapidly exhausted and adheres to the inner wall and the flow path of the vacuum chamber. Particles (dust)
Will be rolled up. On the other hand, if the exhaust gas flow rate is excessively reduced, the exhaust time becomes longer, which adversely affects the production tact. Therefore, conventionally, slow and rapid
A slow exhaust valve that exhausts by step control has been proposed. One such conventional example is disclosed in Japanese Patent Laid-Open No. 9-137.
No. 879. FIG.
FIG. 1 is a sectional view showing a first conventional example of a slow exhaust valve described in the publication.

The slow exhaust valve 100 includes a first body member 101 and a second body member 102.
A main valve mechanism 103 and a sub-valve mechanism 104 are provided in the first body member 101, and a main valve body driving member 105 and a sub-valve driving member 106 are provided in the second body member 102. The main valve mechanism 103 fully opens and closes a flow path connecting the ports 111 and 112, and a main valve element 114 for a main valve seat 113 is connected to a main valve element driving member 105 via a main shaft 115. The main valve element 114 is a bellows 1
16 is urged in a closing direction (downward) by a return spring 117 contained therein, and is opened by supplying a pressure fluid to a main pressure action chamber 131 below the main valve body driving member 105. On the other hand, in the sub-valve mechanism 104, a sub-valve body 120 that opens and closes a sub-valve seat 119 of a flow path 118 formed in the main valve body 114 is connected to a sub-valve drive member 106 by a sub shaft 121. Then, the return spring 122 provided in the main shaft 115 is urged in the closing direction (downward) by the return spring 122, and the auxiliary pressure action chamber 132 below the auxiliary valve body driving member 106.
Is supplied, the sub-valve drive member 106 rises until it comes into contact with the adjusting screw 133, whereby the sub-valve 120 opens the sub-valve seat 119.

When the pressure fluid is first supplied into the sub-pressure action chamber 132, the slow exhaust valve 100 rises to a position where the sub-valve driving member 106 comes into contact with the adjusting screw 133, and the sub-valve seat 119 is moved. Be released. Therefore, gas is restricted from the chamber port 111 to the pump port 112.
And the chamber is slowly evacuated. Next, when the pressure in the chamber is sufficiently reduced to reach a pressure that does not cause turbulence of air enough to wind up the particles, the main valve element 114 is raised. And
The main valve seat 113 is fully opened. At this time, even if the air is sucked at a certain speed due to the low density of air, the remaining exhaust is performed without generating a turbulent flow.

Another conventional example is disclosed in Japanese Patent Laid-Open No. 6-29.
No. 4472 can be mentioned. FIG. 5 is a sectional view showing a second conventional example of the slow exhaust valve described in the publication. This slow exhaust valve 20
0 indicates that the valve seat 203 is provided between the fluid inlet passage 201 and the fluid outlet passage 202 and the metal diaphragm 20
4 which pushes the diaphragm piece 4 toward the valve seat 203 side
05 is connected to the valve stem 206 operated by the actuator. The actuator includes a cylinder 207 for fully opening the valve and a cylinder 208 for slow leak. The cylinder 207 for fully opening the valve includes a piston 211 provided in the middle of the valve rod 206 and a spring 212 for urging the piston 211 downward.
Leak piston 213 fixed to the upper end of valve stem 206
And a spring 214 for urging the same downward.

Therefore, the slow exhaust valve 200 is first operated by the slow leak cylinder 208 using the leak piston 21.
When the metal diaphragm 204 is pushed up against the spring 214 by air, the metal diaphragm 204 having a slightly released pressing force slightly rises due to its own elastic force to open the valve, and a slow leak is performed. Next, when the pressure in the vacuum chamber has risen to a predetermined pressure, the piston 211 is moved by air to the spring 21 by the cylinder 207 for fully opening the valve.
It is pushed up against 2 and is fully opened.

[0007]

However, the slow exhaust valve 100 of the first conventional example has a configuration in which the sub-valve body 120 is provided in the main valve body 114, so that dimensional restrictions arise. There was a problem. That is, since the valve hole of the sub-valve seat 119 is limited by the size of the main valve body 114, for example, if the size of the silicon wafer increases from 8 inches to 12 inches, the volume in the vacuum chamber also increases accordingly. . In such a case, the slow exhaust valve 1
The structure of No. 00 has a drawback that it is difficult to increase the exhaust amount in conformity with the volume in the vacuum chamber, and the slow exhaust time to reach a predetermined vacuum pressure is unnecessarily long. On the other hand, the slow exhaust valve 200 of the second prior art example
Sets the metal diaphragm 204 to the cylinder 20 for fully opening the valve.
7 and the opening by the slow leak cylinder 208, the structure on the drive side makes it easier to adjust the amount of exhaust at the time of slow leak in accordance with the volume in the vacuum chamber than the first conventional example. . However, since the metal diaphragm 204 itself constituting the valve is sandwiched and fixed to the valve box 220, there is a restriction on the amount of bending of the metal diaphragm 204 and the like.

Further, conventional slow exhaust valves 100 and 2
In the case of 00, there was a problem in the structure of the cylinder portion, in addition to the problem of adjusting the displacement in accordance with the volume in the vacuum chamber. That is, the slow exhaust valve is generally provided with two cylinders in order to drive slow exhaust and rapid exhaust in two stages. Specifically, the slow exhaust valve 1
00, the second body member 102 and the main valve body driving member 1
05, and the slow exhaust valve 200 is also composed of two members, a valve fully open cylinder 207 and a slow leak cylinder 208. Conventionally, these two cylinders are formed and assembled as separate members, respectively, so that dimensional accuracy of each part is required at a high level in order to achieve concentricity during assembly, which causes an increase in product price. Was.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a slow exhaust valve which is not restricted by adjusting the displacement, and to provide a slow exhaust valve having high concentric accuracy at a low cost.

[0010]

A slow exhaust valve according to the present invention is provided with a valve seat formed in a valve body having a pump port and a chamber port, and is constantly urged toward the valve seat side. A valve body provided in the valve body for contacting / separating, a main shaft having a lower end fixed to the valve body, and a lower main piston positioned above and below the main shaft and fixed to the main shaft And an upper sub-piston in which the main shaft is slidably fitted to prevent the upper piston from coming off from the upper end, and an intermediate wall partitioning a pair of upper and lower piston chambers in which the main piston and the sub-piston slide. A cylinder tube formed from one cylindrical body, and pressurizes and operates the main piston and the sub-piston upward by a working fluid supplied to each of the piston chambers, to the valve seat via a main shaft. Height of the valve body And performing adjustment.

Therefore, in the slow exhaust valve of the present invention,
When the sub-piston is pressurized and rises, the main shaft is lifted by the sub-piston, the valve body is slightly separated from the valve seat and slow exhaust is performed, and then if the main piston is pressurized and rises, The main shaft is further moved up together with the main piston, and the valve body is largely separated from the valve seat to perform rapid exhaust. Therefore, the slow exhaust valve of the present invention performs slow exhaust and rapid exhaust with a single valve element that freely moves independently of the valve body to adjust the separation distance from the valve seat, so that the valve opening can be freely adjusted. It can be adjusted and adapted to vacuum chambers of different volumes. In addition, the slow exhaust valve of the present invention includes a cylinder tube formed of one cylindrical body having an intermediate wall that partitions a pair of upper and lower piston chambers into upper and lower parts, for example, a solid member formed by cutting both upper and lower parts. By forming a cylinder tube with an intermediate wall provided at a predetermined intermediate position between
The manufacturing cost of the cylinder has been reduced, and high concentricity has been achieved.

Further, in the slow exhaust valve according to the present invention, the valve body includes a seal portion which directly contacts and separates from the valve seat surface;
And a needle portion having a tapered surface formed in a circumferential shape and entering a valve hole in the valve seat. Therefore, by using a needle part having a different external dimension or taper angle, it has become possible to correspond to various kinds of vacuum chambers having different internal volumes.

[0013]

Next, an embodiment of a slow exhaust valve according to the present invention will be described with reference to the drawings.
1 to 3 are sectional views showing an embodiment of a slow exhaust valve. FIG. 1 is a view showing a closed state, FIG. 2 is a slow exhaust state, and FIG. 3 is a view showing a rapid exhaust state. . The slow exhaust valve 1 includes a lower valve portion and an upper cylinder portion. The valve portion is constituted by a cylindrical valve body 10 having a pump port 11 protruding laterally and a chamber port 12 protruding downward.
The valve body 10 has a valve hole 1 on the chamber port 12 side.
The valve seat 13 having a flat surface is formed at the inlet 4 and the valve seat 13
Is provided with a valve body 20 that comes into contact with and separates from the valve body 20. Valve body 20
A sealing valve body rubber 22 that directly contacts the valve seat 13 with respect to the valve body block 21 is held, and a needle valve body 23 that projects further downward and enters the valve hole 14 as shown in FIG. It is integrally screwed to the main shaft 25.

A valve block 21 constituting the valve 20
Is connected to a lower end of a metal bellows 26, and an annular fixing plate 27 is connected to an upper end of the metal bellows 26 to form a bellows assembly. On the other hand, in the upper cylinder portion, a cylindrical cylinder tube 30 is provided with a bottom cover 31 and an upper cover 3.
2 is closed. This cylinder tube 30 forms an internal space by shaving a solid cylindrical material from both the upper and lower sides, and forms an intermediate wall 30a at a predetermined intermediate position.
It has. Therefore, the cylinder tube 30
The main piston chamber 33 and the sub-piston chamber 34 are formed at the top and bottom by one.

The bottom cover 31 closing the lower end opening of the cylinder tube 30 is also configured to close the upper end opening of the valve body 10. That is, the cylinder tube 3
The bottom cover 31 screwed and integrated with the valve body 1
The fixing plate 27 of the bellows assembly is inserted between the valve body 10 and the fixing plate 27 and is held by a tightening nut 29 screwed into the valve body 10 from above. Thus, the slow exhaust valve 1 is configured by integrating the valve body 10 and the cylinder tube 30. The main shaft 25 fixed to the valve body 20 penetrates the bottom cover 31, is slidably supported at the penetrating portion, and extends into the cylinder tube 30. Therefore, the metal bellows 26 is arranged so as to surround the main shaft 25, so that the fluid in the valve body 10 does not leak from the through hole of the bottom cover 31 on which the main shaft 25 slides to the cylinder portion. A spring 28 is disposed between the valve body 20 and the bottom cover 31 in the metal bellows 26,
The valve body 20 is constantly biased toward the valve seat 13 side.

The cylinder tube 30 extends through the bottom lid 31.
The main shaft 25 extending inward penetrates an intermediate wall 30a that separates a lower main piston chamber 33 from an upper sub piston chamber 34. A main piston 35 that slides up and down in a main piston chamber 33 is fixed to the main shaft 25, and a sub piston 36 that slides up and down in a sub piston chamber 34 is penetrated by the main shaft 25. The sub-piston 36 has an outer peripheral portion sliding with respect to the cylinder tube 30 and an inner peripheral portion
And a locking ring 37 is provided at the upper end of the main shaft 25.

A main piston operation port 38 and a sub piston operation port 39 are provided on the side of the cylinder tube 30.
Are formed, and the main piston 35 or the sub piston 3
6 to the main piston chamber 33 or the sub-piston chamber 34 so that the compressed air as the working fluid can be supplied below
8a and 39a. By the way, an adjusting screw 41 for restricting the amount of movement of the sub piston 36 is provided on the upper lid 32 of the cylinder tube 30. Top lid 3
2, a hole 32a is formed at the center so that the main shaft 25 protrudes, and a cylindrical adjustment screw 41 having a flange portion is screwed into the hole 32a. The adjusting screw 41 adjusts the height by rotating in accordance with a scale plate 42 attached to the upper lid 32, and is provided with a fixing screw 43 for positioning at a predetermined height. I have.

Therefore, in the slow exhaust valve 1 having such a configuration, vacuum exhaust is performed by the following operation. When the valve is closed, the slow exhaust valve 1 is in a state where the valve body rubber 22 of the valve body 21 is in contact with the valve seat 13 and the valve hole 14 is closed as shown in FIG. This is because the valve body 20 is urged downward only by the elastic force of the spring 28. When evacuating a vacuum chamber (not shown) connected to the chamber port 12, the following two-step operation for slow exhaust and rapid exhaust is performed.

First, compressed air is supplied from the sub-piston operation port 39 to the sub-piston chamber 34 below the sub-piston 36 in order to perform slow exhaust. Therefore, the secondary piston 3
6 is pressurized from below and rises in the sub piston chamber 34. The auxiliary piston 36 first rises independently of the main shaft 25, but hits the locking ring 37 when it rises by a certain amount, and rises so as to push up the locking ring 37. Therefore, the main shaft 25 is lifted by the sub-piston 36 against the downward biasing force of the spring 28, the valve body rubber 22 of the valve body 20 is separated from the valve seat 13, and the blocking is released. On the other hand, the secondary piston 36 hits the lower end of the adjusting screw 41 when the main shaft 25 is further raised by a certain amount after the main shaft 25 is lifted, and the movement thereof is restricted. Therefore, spindle 2
The lifting of the valve 5 and the valve body 20 is also stopped, and the position shown in FIG. 2, that is, the state of the valve opening suitable for performing the slow exhaust, is maintained.

The slow exhaust valve 1 has a small valve opening in the slow exhaust state shown in FIG. 2, and the fluid flowing between the pump port 11 and the chamber port 12 causes the fluid between the valve seat 13 and the needle valve body 23 to pass through. It flows through the gap and its flow rate is limited. Therefore, the gas in the vacuum chamber does not flow rapidly, and the slow exhaust is performed without rolling up the particles. Then, when the pressure in the vacuum chamber becomes sufficiently low, the subsequent rapid exhaust is performed. When performing rapid exhaust, compressed air is supplied to the slow exhaust valve 1 from the main piston operation port 38 to the main piston chamber 33 below the main piston 35. Therefore, the main piston 35 is pressurized from below and the main piston chamber 3
Go up in 3. At this time, the main shaft 25 is connected to the main piston 33
, It rises as the main piston 33 rises. Accordingly, the valve body 20 fixed to the main shaft 25 rises against the urging force of the spring 28, and the valve is opened with the valve opening increased as shown in FIG.

When the slow exhaust valve 1 is in the rapid exhaust state shown in FIG. 3, the valve opening is large, the flow rate between the pump port 11 and the chamber port 12 increases, and the gas remaining in the vacuum chamber is rapidly reduced. Exhausted. When the exhaust of the gas in the vacuum chamber is completed, the compressed air is extracted from the main piston operation port 38 and the sub piston operation port 39, and the main piston 35 and the sub piston 36 are compressed by the compressed air that has been pushed up from below. Release from pressure. Therefore, the valve body 20, the main shaft 25, the main piston 35, and the sub-piston 36 are urged downward by the spring 28 to return to the state shown in FIG. That is, the valve body rubber 22 of the lowered valve body 20 comes into contact with the valve seat 13, and the pump port 11 and the chamber port 12 are shut off.

Therefore, the slow exhaust valve 1 of the present embodiment can perform two-stage exhaust of slow exhaust and rapid exhaust by operating the main piston 35 and the sub piston 36. Is adjusted by one valve body 20 which freely moves independently of the valve body, so that the exhaust amount is adjusted to the volume in the vacuum chamber by adjusting the valve opening during slow exhaust. You can now make it bigger. The adjustment can be performed accurately and easily by the adjustment screw 41. Therefore, for example, the slow exhaust valve 1 can be connected to two vacuum chambers having different capacities, and one vacuum exhaust valve can be used for both. The slow exhaust valve 1 is provided with a valve body 20.
Is provided with the needle valve element 23, so that it is possible to cope with various kinds of vacuum chambers having different internal volumes by using the needle valve element 23 having different outer dimensions and taper angles.

Further, the slow exhaust valve 1 of the present embodiment
In the above, the cylinder tube 30 constituting the main piston chamber 33 and the sub piston chamber 34 is integrally formed by cutting from both upper and lower sides. In addition, in today's advanced cutting technology, it is easy to make the two chambers concentric. As a result, since the dimensional accuracy of each component constituting the cylinder tube is not required in order to obtain concentricity as in the related art, the manufacturing cost of the cylinder part can be reduced, and high concentricity can be realized. . In addition, since the cylinder tube 30 formed integrally by cutting has a long axial dimension,
The communication passage 38a formed in the cylinder tube 30 can be lengthened in the axial direction. Therefore, the degree of freedom in selecting the height position of the main piston operation port 38 is increased, and an appropriate port position can be set according to the installation environment of the slow exhaust valve 1.

It should be noted that the present invention is not limited to the slow exhaust valve of the above embodiment, and various changes can be made without departing from the gist of the present invention.

[0025]

According to the present invention, a valve body is provided in a valve body so as to come into contact with and separate from a valve seat, and a main piston and a sub-piston provided on a main shaft integral with the valve body are slid vertically. Since the piston chamber has a configuration having a cylinder tube formed from a single cylindrical body having an intermediate wall that separates the upper and lower parts, it is possible to provide a slow exhaust valve that is not restricted by the adjustment of the displacement. It has also become possible to provide a low-cost slow exhaust valve with high concentric accuracy.

[Brief description of the drawings]

FIG. 1 is a sectional view of a slow exhaust valve according to an embodiment of the present invention in a closed state.

FIG. 2 is a sectional view of a slow exhaust valve according to an embodiment of the present invention in a slow exhaust state.

FIG. 3 is a cross-sectional view illustrating a slow exhaust valve according to an embodiment of the present invention in a rapid exhaust state.

FIG. 4 is a sectional view showing a first conventional example of a slow exhaust valve.

FIG. 5 is a sectional view showing a second conventional example of the slow exhaust valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Slow exhaust valve 10 Valve body 11 Pump port 12 Chamber port 13 Valve seat 21 Valve 23 Needle valve 25 Main shaft 30 Cylinder tube 33 Main piston chamber 34 Secondary piston chamber 35 Main piston 36 Secondary piston 41 Adjustment screw

Claims (3)

[Claims] 1. A valve seat formed in a valve body having a pump port and a chamber port, and is provided in the valve body so as to be constantly urged toward the valve seat and to abut and separate from the valve seat. A valve body, a main shaft having a lower end fixed to the valve body, a lower main piston positioned above and below the main shaft, and a lower main piston fixed to the main shaft, and a main shaft slidably fitted with the upper end. And a pair of upper and lower piston chambers in which the main piston and the sub-piston slide are formed from a single cylindrical body having an intermediate wall separating the upper and lower parts. And operating the main piston and the sub-piston by pressurizing the main piston and the sub-piston upward by operating fluid supplied to each of the piston chambers, and adjusting the height of the valve body with respect to the valve seat via a main shaft. And slow exhaust bar Breakfast. 2. The slow exhaust valve according to claim 1, wherein the cylinder tube has an internal space formed by cutting a solid member from both upper and lower sides, and an intermediate wall is provided at a predetermined position intermediate the solid member. A slow exhaust valve, characterized in that: 3. The slow exhaust valve according to claim 1, wherein the valve body has a seal portion directly in contact with and separated from the valve seat surface, and a tapered surface formed in a circumferential shape, and the inside of the valve seat is formed. And a needle portion that enters the valve hole.