JPS63138177A - Bellows pump - Google Patents

Abstract

PURPOSE:To enable early sensing of leakage by forming an air release groove for releasing the varying pressure in bellows to the atmosphere, and by fitting in this groove an electrode sensor, which is to sense any leakage of the processing liquid from outside the casing. CONSTITUTION:A bellows pump pressurizes the fluid sucked from a suction hole 47 through a check valve 7 and discharges from a discharge hole 33 by expanding and contracting two sets of bellows 1 alternately in pump chambers 25 installed at the ends of a casing 15. Expansion/contraction of the bellows 1 is made through a shaft 2 by applying air pressure alternately to a pair of pressure chambers 22. Here an air release groove 32 to put the space in bellows 1 in communication with the atmosphere is formed at a flange 10 fixed to the casing 15 at one of the ends of bellows. From outside, an electrode sensor 35 is fitted in this air release groove 32 so as to sense any leakage of the processing liquid such as etching liquid for semiconductor.

Description

[Detailed description of the invention] [Industrial application field]

The present invention provides chemical solutions such as strong acids, strong alkalis, and organic solvents,
This article concerns a bellows pump suitable for metered pressure pumping of other fluids.

[Prior art]

Generally, a bellows pump is used as one type of metering pump that accurately discharges a desired liquid m at a specified pressure. It is mainly used for constant meter pressure delivery of chemical solutions such as strong acids, strong alkalis, or FT machine solvents. may be pumped in fixed quantities. FIG. 4 is a schematic diagram showing the basic configuration of this bellows pump, and the operation of the bellows bonnet will be explained according to this diagram. 3 in the figure shows the operating part of the pump,
A pair of bellows! ,! By alternately expanding and contracting the pump chambers 25.25° defined at both ends of the casing 15, a discharge pressure and a suction pressure are generated. Reference numerals 4, 5, and 6°7 are check valves, 47 is an inlet, and 33 is an outlet. When one bellows l° contracts and the other bellows l expands, check valve 4.6
is opened, check valves 5 and 7 are closed, and the liquid being pumped is sucked into one pump chamber 25° from the suction port 47 through the check valve 6, and the liquid that was in the other pump chamber 25 is is fed under pressure through the check valve 4 and from the discharge port 33 to the supply system. Note that the check valves 5゜7 that are closed at this time are on the discharge side and
It performs a rectifying function by preventing backflow on the suction side. Each bellows l. When B performs the reverse operation, each check valve 4゜5, G
, 7 are operated in reverse, and the liquid is similarly sucked in from the suction port 47 and pumped through the discharge port 33 to the supply system. Also, when the bellows expands and contracts by 1.1 degrees, both ends are each bellows! , 1', and a shaft portion 44' fixed to the inside of the distal end thereof.
The drive is performed by pistoning 2 in the axial direction. This piston movement of the shaft member 2 is caused by a casing-side partition 48 that airtightly and slidably holds the substantially central portion of the shaft member 2, and a shaft member located on both sides of the casing-side partition 48. A shaft-side partition wall 1 that extends outward in the radial direction from 2 in a brim shape, and whose peripheral edge portion slides in airtight contact with the inner circumferential surface of the casing 15.
In the two pressure chambers 22, 22° formed between the
It is driven by alternately applying air pressure. Also, the volumes inside the bellows t and t' are bellows 1. ! Since the pressure changes with the expansion and contraction movement of the bellows 1, 1, an air escape hole 32 opened to the atmospheric pressure side is formed to absorb the accompanying pressure fluctuation within the bellows 1,1. In the figure, 50 is a driving air pressure switching valve.

[Problems to be solved by the invention]

By the way, as mentioned above, bellows 1. The reason why the pressure chambers 22° and 22° are interposed without directly applying driving air pressure inside I is that the configuration with the highest risk of leakage is the bellows 1.1°. For example, when an etching solution for semiconductors is pumped, it is pumped at a high temperature in order to increase the reactivity of the etching solution, but when the temperature reaches a high temperature of 100°C or higher, the fluororesin gradually softens and its rigidity decreases. is decreasing. As a result, bellows! . Cracks or pinholes may occur in the LO, causing the etching liquid to leak, or grease from the switching valve, etc. (which evaporates into grease vapor and is included in the driving air) to mix into the etching liquid. In response to this fear, even if the bellows 1, 1' are damaged, the structure is designed to prevent contact between the driving air and the fluid to be pumped. However, extremely high purity (in Pr'n units) is required for semiconductor etching solutions, and even a small amount of contamination cannot be ignored. If damage occurs, it is desirable to detect it quickly and prevent further leakage. Conventional bellows pumps do not have this early detection function as a leak countermeasure, and this remains a problem. The present invention has been devised in view of the above problems and to effectively solve them. Therefore, the purpose is to quickly detect damage to the bellows and prevent the leakage of the pressurized fluid from developing.7. ,l-,
An object of the present invention is to provide a highly reliable bellows pump that can prevent grease or the like from getting into the L-tl-)jυ pressure cylinder.

[Means to solve the problem]

The bellows pump according to the present invention has the following configuration in order to solve the problems of the prior art and achieve the objective. In other words, it is a bellows pump in which the part that comes into contact with the fluid to be pumped is made of fluororesin, and in order to release the fluctuating pressure inside the bellows that occurs due to the expansion and contraction of the bellows to atmospheric pressure, the space inside the bellows and the bellows An air relief groove is formed that communicates with the outside of the pump casing. Further, an electrode sensor is inserted into the air relief groove from outside the casing and is installed facing the inner space of the bellows to stop the driving air pressure source in a conductive state. Preferably, the core wire of the electrode sensor is made of platinum wire and covered with a fluororesin duplex.

[Effect]

According to the bellows pump according to the present invention, the electrode of the electrode sensor can be inserted into the bellows using the air relief R+7 that absorbs pressure fluctuations within the bellows. The electrode sensor stops the driving air pressure source in a conductive state, but when there is a leak of the chemical liquid from the bellows, the chemical liquid tends to flow out from the air escape 11-1 as the air inside the bellows flows. The electrode is immersed in the chemical solution in this groove and becomes conductive, stopping the driving pneumatic source. The electrodes of the electrode sensor are platinum-core wires and are coated with fluororesin, so they are not attacked by strong acid or strong alkaline chemicals.

【Effect of the invention】

As is clear from the following explanation, the present invention exhibits the following excellent effects. In other words, even if a crack or pinhole occurs in the bellows and the chemical leaks,
This can be detected immediately and the operation of the bellows pump can be stopped to take immediate action, thereby preventing further contamination of the chemical solution. Therefore, the reliability of the bellows pump can be further improved.

【Example】

A preferred embodiment of the present invention will be described below with reference to FIGS. 1 to 4.
Please refer to the diagram for explanation. FIG. 1 is a half-sectional front view of a bellows pump according to the present invention. An actuating part 3 including a bellows 1 and a shaft member 2, etc. is located approximately in the center of the pump body, and check valves 4, 5, 6, and 7 are arranged at the four corners around it. is almost the same as that shown in FIG. 4 explained in the section of the prior art. Therefore, similar configurations will be given the same numbers as '3. A repeated explanation will be omitted, and the detailed configuration will mainly be described here. It should be noted that the actuating section 3 is constructed almost symmetrically in the same way as in the prior art, and the parts that are shown in the interrupted plane and the parts that are not shown have the same structure. The shaft member 2 has bellows l (
The shaft member 2 is connected to the center of the inner surface of the head 8 (one not shown) via a connecting pusher 14, and as the shaft member 2 moves as a piston within the casing 15, the bellows 1 alternately expand and contract. A disk-shaped pressure receiving portion 16 is formed on the shaft member 2 as a shaft-side partition wall portion that receives driving air pressure to participate in driving the shaft member 2 . In addition, in order to increase the discharge pressure by the bellows 1, the diameter of the disk is set so that the pressure receiving area is larger than the area of the head 8 of the bellows 1. The shaft member 2 including this disk-shaped pressure receiving part 16
The casing 15, which holds the bellows 1 while allowing the piston interlocking and the expansion and contraction movement of the bellows 1, has four main parts: a central drum part 17, a first cylinder part 18, a second cylinder part 19, and a holding part 20, which will be explained below. It consists of: First, in the center of the casing 15, there is a shaft member 2.
Center part (left and right! Connecting part between the pair of disc-shaped pressure receiving parts)
A central drum portion 17 is provided which slidably and airtightly holds the drum and which is provided with an inlet 21 for driving air pressure. Although not shown in FIG. 1, this central drum portion 1
Various mechanisms for switching the supply of driving air pressure to the left and right actuating parts are housed in the unit 7. A first cylinder part 18 is provided adjacent to both sides of the central drum part 17, and the end face of the central drum part 17 serves as a casing-side partition part, and the inner peripheral surface of the first cylinder part 18 and the disc-shaped pressure receiving A pressure chamber 22 is formed by portion IG. That is, the disk-shaped pressure receiving part 16 of the shaft member 2 has its circumferential surface slidingly in contact with the inner circumferential surface of the first cylinder part 18 while being sealed therebetween, and the piston moves to expand and contract the pressure chamber 22. do. As shown in FIG. 1, the first cylinder section 18 roughly consists of a cylindrical section 23 and a disk section 24, and the end of the shaft member 2 is slidable in the center of the disk section 24. It is held in Further, a second cylinder portion 19 is provided adjacent to the first cylinder portion 18 . A bellows is housed in the second cylinder portion 19, and a pump chamber 25 is formed in which the medicinal liquid is sucked and discharged. A ring-shaped holding part 20 is provided which fits into the peripheral edge of the second cylinder part 19 and tightens and fixes it to the first cylinder part 18. For tightening, a bolt 2G is used as a fixing means. Each component of the casing 15 must maintain airtightness at each assembly point, and must have enough strength to withstand the force of strong tightening of the bolts 26 and the like. Therefore, the bellows l and the second cylinder part 1
Components other than the parts that come into contact with the chemical solution, such as 9, are made of stainless steel, which is resistant to temperature changes.
In particular, the surface of the first cylinder portion 18 is coated with a fluororesin in order to protect against any possible leakage of the chemical solution. By the way, in fixing the bellows I to the casing 15, the flange portion lO extending outward in one violet direction at the end of the bellows 1 is the first cylinder portion! 8 and the second cylinder portion 19 and are tightened. Further, an annular convex portion 28 that protrudes from the disk-shaped portion 24 of the first cylinder portion 18 is in contact with the inner circumferential surface of the flange portion 10 along this side. This is the conventional flange part 1
0, the width was narrow and the first
When tightening the flange portion IO and the second flange portion 10, the force acts on the flange portion IO obliquely from the outside in the radial direction, so that the bellows l is elongated by 1? i While repeating the M movement, the flange section! 0 gradually shifts inward in the radial direction, which may impair the airtightness of this part, and this structure is designed to prevent this. That is, the configuration in which the flange portion 10 is widened is as follows.
This not only increases the sealing surface, but also contributes to preventing the above-mentioned inward tilting of the flange portion 10 and shifting. Next, the structure of the plate-shaped portion 24 of the first cylinder portion I8 will be explained. Figure 2 shows the first cylinder part of this embodiment! 8 is a side view of FIG. 8 viewed from the disk-shaped portion 24 side. As not shown in the figure, a boss portion 29 is formed in the center to allow the shaft member 2 to be inserted therethrough and supported. The holes formed at three locations around the boss portion 29 absorb most of the air pressure fluctuations within the bellows 1 as the bellows 1 expands and contracts. This is a communication hole 31 for preventing leakage to the chamber 30 formed between the pressure receiving part 16 and the pressure receiving part 16 . These communication holes 31 are, for example, bellows! may be damaged or the flange portion lO of the bellows l
Even if the airtightness of the bellows 1 is broken and a chemical solution such as an etching solution flows into the bellows 1, the chemical solution will leak into the communication hole 3! Three locations are formed at high positions above the center to prevent the fluid from flowing into the chamber 30 side. In the figure, 28 is an annular convex portion that protrudes annularly along the inner circumferential surface side of the flange portion IO of the bellows l, and extends inward from the annular convex portion 28 from the lowest end of the disc-shaped portion 24 toward the center. All the way to
Above communication hole 3! An air relief groove 32 is formed as an air relief hole for releasing air pressure fluctuations in the bellows l, which cannot be completely released, to atmospheric pressure. Also, this air release 1
An electrode sensor 35 having two platinum core wires 33 and 34 is inserted into M32. This electrode sensor 35 is
As shown in FIG. 3, each core wire 33, 34 is surrounded by a tube 36 of polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), and has a bellows! They are exposed from the covering tube 36 to such an extent that their tips do not come into contact with each other due to the flow of internal air. Therefore, if a crack or pinhole occurs in the bellows l and the chemical liquid leaks, the chemical liquid that has leaked into the bellows l will flow in the bellows l and pass through the air relief groove 32 in the direction of gravity. Trying to flow out of 15. Platinum and fluororesin are stable against strong acid and strong alkaline chemicals and will not be attacked. Core line 3 due to leak at medicine station
3.34 is immersed in the chemical solution and 7.d is electrically conductive, and a relay unit (not shown) is cut off to turn off the power to the compressor (not shown) that is the driving air pressure source. Therefore, the operation of the bellows pump is automatically stopped when the chemical solution leaks, and further progress of the leak can be prevented. In addition, each of the wires, which are wrapped by a PFA tube 36, is bundled into one and further covered with a heat-shrinkable PF tube 37.
32 must extend radially inward from the outer circumferential end to a position that slightly touches the annular convex portion 28 (indicated by a virtual line in the figure) in order to function as a shear to absorb pressure fluctuations within the bellows l. ), but in this case, the core wire is 33°3
4 is located very close to the wall of the annular protrusion, so there is a risk of it coming into contact with this wall and causing malfunction. and extends further inward. According to the various structures described above, even if a crack or pinhole occurs in the bellows and a chemical leak occurs, this can be detected immediately, and the operation of the bellows pump can be stopped to take immediate action. Progress of contamination of the chemical solution can be prevented. Therefore, the reliability of the bellows pump can be further improved.

[Brief explanation of the drawing]

FIG. 1 is a half-sectional front view of a bellows pump according to the present invention;
Fig. 2 is a side view of the first cylinder part in this embodiment, Fig. 3 is a perspective view showing the schematic configuration of the tip portion of the electrode sensor in this embodiment, and Fig. 4 shows the basic configuration of the bellows pump. Schematic diagram of check valve, 7... suction side check valve,
Death: Bellows head, 9 bellows bellows,
lO...Bellows flange portion, 14...Connecting push, 15...Casing, 16...Disc-shaped pressure receiving part, 17...Central drum part, 18...
First cylinder part! 9...Second cylinder part, 20...
- Holding part, 21... Drive air pressure inlet, 22...
Pressure chamber, 23... Cylindrical part of the first cylinder part, 24...
- Plate-shaped part of the first cylinder member, 25... pump chamber, 2
6... Bolt, 27... Additional tightening allowance, 28... Annular convex portion, 29... Boss portion, 30... Chamber, 31...
Communication hole, 32...Air escape force L iM, 33.3-1
...Core wire, 35... Electrode sensor, 36.37...
Fluororesin tube patent applicant Kurashiki Boseki Co., Ltd. agent Patent attorney Aohaku Ao (and 2 others) s2 figure height 3■ Figure 4

Claims (2)

[Claims] (1) A bellows pump in which the part that comes into contact with the fluid to be pumped is made of fluororesin, and the bellows (1) that is generated as the bellows (1) expands and contracts.
1) An air relief groove (32) is formed that communicates the internal space of the bellows with the outside of the casing (15) of the bellows pump in order to release the fluctuating pressure inside to the atmospheric pressure side. The air relief groove (3
2) A bellows pump characterized in that an electrode sensor (35) that is inserted into the bellows and stops the driving air pressure source in a conductive state is installed facing the inner space of the bellows. (2) The electrode sensor (35) has electrodes made of platinum core wires (33, 34) and a fluororesin tube (3
6, 38) The bellows pump according to claim 1, wherein the bellows pump is coated with