JP2002174180A - Bellows pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain stable sealing performance of a bellows sealing part, to carry out favourable centering of a pump shaft and to prevent torsion at the time of assembly. SOLUTION: Bellows 12 are attached on both sides of a pump head 11, and pump chambers are respectively formed inside. A pair of cylinders 1 is coaxially arranged against the bellows 12 so as to store the bellows 12. Opening edge parts 1c, 1d to cover the outer peripheral side of a connecting part of the pump head 11 and the bellows 12 are formed on end parts against which the cylinders 1 face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bellows pump for transferring a liquid using a pair of bellows which are driven to expand and contract alternately.

[0002]

2. Description of the Related Art Conventionally, as a liquid injection pump used for cleaning a semiconductor wafer, for example, a pump disclosed in Japanese Utility Model Application Laid-Open No. 3-102078 by the present applicant has been proposed.
2. Description of the Related Art A bellows pump that sucks and discharges a liquid by using a bellows made of a fluororesin is known. FIG. 4 is a perspective view showing the appearance of a conventional bellows pump of this type.
The bellows pump includes a disk-shaped pump head 51,
The pump head 51 includes cylindrical cylinders 52a and 52b coaxially arranged on both sides of the pump head 51, and cylinder heads 53a and 53b arranged on both sides thereof. The pump head 51 is connected to a suction port 54 and a discharge port 55 of the liquid to be transferred. Also, the cylinder head 53
Air supply ports 56a and 56b for supplying gas, for example, air, for reciprocating the bellows mounted therein are provided on the side surfaces of the bellows 53a and 53b.

FIG. 5 is a longitudinal sectional view showing the internal structure of the bellows pump. A pair of bellows 61a, 61b are provided on both surfaces of the pump head 51 in the cylinders 52a, 52b.
1b is mounted. These bellows 61a, 61b
The mounting portion 62 has a cylindrical shape with a bottom and an annular shape on the opening side.
a and 62b are formed so as to be in close contact with the pump head 51, and the bottoms constitute disk-shaped movable plates 63a and 63b, which are integrally connected via elastic portions 64a and 64b having a bellows structure. The bellows 61a and 61b and the pump head 51 form two sealed variable capacity cylindrical pump chambers 65a and 65b. The pump head 51 is provided with suction-side valve units 66a and 66b communicating with the liquid suction port 54 and discharge-side valve units 67a and 67b communicating with the liquid discharge port 55.

The cylinder heads 53a and 53b are provided with a cylinder head body 71 for closing both sides of the cylinders 52a and 52b.
a, 71b and the cylinder head bodies 71a, 71b
And cylinder head covers 72a and 72b for closing the inside of the cylinder head. The cylinders 52a and 52b and the cylinder head bodies 71a and 71b are
Air chambers 81a and 81b which are hermetically closed are formed outside of b. The cylinder head main bodies 71a, 71b have a center hole through which pump shafts 75a, 75b extending along the center axis of the cylinders 52a, 52b are inserted through bearings 73 and seals 74. The inner ends of the pump shafts 75a, 75b are bellows 61a,
61b is connected to the movable plates 63a and 63b, respectively, and the outer ends are connected to the connection plates 76a and 76b, respectively. The upper and lower ends of the connecting plates 76a, 76b are connected to each other by connecting shafts 77a, 77b. The connection shafts 77a and 77b are connected to the cylinder head body 71.
a, cylindrical shaft cover 7 suspended between 71ab
8a and 78b are slidably accommodated in the axial direction.

Further, as shown in FIG. 4, flange portions 79 projecting right and left toward the center axis direction of the cylinders 52a and 52b are formed on the cylinder head main bodies 71a and 71b.
a, 79b are formed. This flange portion 79a,
79b are connected by, for example, four stud bolts 82, whereby the cylinder head bodies 71a,
71b, the cylinders 52a and 52b, the bellows 61
The ends of the mounting portions 62a and 62b of the a and 61b and the pump head 51 are sandwiched and fixed.

In the bellows pump having this configuration, when air is alternately supplied from the air supply port 56a to the air chambers 81a and 81b, the bellows 61a and 61b alternately expand and contract alternately.
The pump operation is such that the transfer fluid is introduced into the pump chambers 65a and 65b through the pump chambers 6a and 66b, and the fluid introduced into the pump chambers 65a and 65b is discharged from the discharge port 55 through the discharge side valve units 67a and 67b. repeat.

[0007]

In the bellows pump configured as described above, the PTFE is attached to the bellows 61a and 61b and the pump head 51 in consideration of the transfer of the chemical solution and the like.
In many cases, a corrosion-resistant resin such as (polytetrafluoroethylene) is used. However, since PTFE has high lubricity, the joint between the bellows 61a, 61b and the pump head 51 may creep under the influence of the vibration or heat of the pump, and the sealing performance may be impaired. Therefore, conventionally, in order to secure sufficient sealing performance, it is necessary to retighten the stud bolts 82 connecting the cylinder heads, which may cause deformation of the members.

In the conventional bellows pump described above, the cylinder heads 71a, 71b, the cylinder 52a,
Since the pump is composed of a total of seven parts 52b, bellows 61a, 61b, and pump head 51, which are superposed in the axial direction, the centering of the pump shaft is insufficient due to the respective dimensional errors and the degree of fitting. Or twisting between the members. For this reason, the center axes of the shaft covers 78a and 78b and the connecting shafts 77a and 77b do not coincide with each other, and the two rub against each other, increasing the sliding resistance and causing the generation of abrasion powder (particles). .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and can maintain a stable sealing performance of a bellows seal portion for a long period of time without requiring additional tightening of stud bolts. It is a first object to provide a bellows pump. It is a second object of the present invention to provide a bellows pump capable of favorably setting the center of a pump shaft and preventing torsion during assembly.

[0010]

SUMMARY OF THE INVENTION A bellows pump according to the present invention is provided with a disk-shaped pump head and two pump chambers formed on both sides of the pump head so that their opening sides face each other. A pair of bellows having a bottomed cylindrical shape, each of which is extendable and contractable in the axial direction, and the pump head is disposed coaxially with respect to the bellows so as to respectively accommodate the pair of bellows therein, and opposed to each other. And a pair of cylindrical cylinders sandwiching the connecting portion of the bellows from both sides, and closing the openings of the pair of cylinders opposite to the pump head so that the gas chambers together with the cylinders are located outside the bellows. A pair of cylinder heads respectively forming cylinder heads, cylinder head coupling means for coupling these cylinder heads to each other, and the pair of cylinder heads. And a pair of pump shafts each penetrating airtightly and slidably along the central axis of the cylinder and having one end connected to each bottom of the pair of bellows, and the other end of the pair of pump shafts being fixed. A shaft connecting means for connecting at a distance between the pump chamber and the pump head in the pump chamber to guide the transfer fluid from the suction port of the transfer fluid to the pump chamber and discharge the transfer fluid from the pump chamber. A bellows pump having a valve unit for guiding the transfer fluid to the pump, wherein the cylinder has an opening edge portion covering an outer peripheral side of a coupling portion between the pump head and the bellows.

According to the present invention, the pump head and the bellows are provided with an opening edge which covers the connecting portion from the outer peripheral side at the end of the cylinder which sandwiches the connecting portion between the pump head and the bellows from both sides. Is constrained from moving in the radial direction by the opening edge of the cylinder. For this reason, the member constituting the connecting portion between the pump head and the bellows does not move even by the influence of the vibration or heat of the pump, and a stable sealing performance is always provided without retightening stud bolts or the like. Can be maintained. Further, since the positions of the pump head and the bellows in the radial direction are regulated, the centering accuracy between these members and the cylinder is increased. As a result, the margin for the stress amplitude on the seal portion generated by the reciprocating motion of the bellows increases, so that the number of strokes of the pump can be increased and the pump can be further speeded up.

In a preferred embodiment of the present invention,
One end of the pair of cylinders facing each other is formed with a convex shape and the other with a concave shape to form concave and convex portions to be fitted to each other. With such a configuration, the relative position of the cylinder in the circumferential direction is uniquely determined by the concave and convex portions, so that circumferential twisting does not occur when the pump is assembled. By centering and preventing torsion in this way, the sliding resistance of the pump can be reduced, and the pump can be made faster and more compact.

In a further preferred aspect of the present invention, the housing is formed by integrally forming the cylinder and the cylinder head. Thus, when the cylinder and the cylinder head are formed integrally, there is no center displacement between the cylinder and the cylinder head, so that centering with higher accuracy can be performed.

The pair of cylinder head connecting means is, for example, a plurality of stud bolts arranged around the cylinder in parallel with the center axis of the cylinder. Further, the shaft connecting means includes, for example, a plurality of shaft covers mounted between the cylinder heads in parallel with the central axis of the cylinder, and a plurality of connecting shafts slidably accommodated in the shaft covers in the axial direction. And a connecting body that connects each end of these connecting shafts together with each other end of the pump shaft. In addition, if a lip seal made of fluororesin is attached to a portion of the cylinder head where the pump shaft slides, the sliding resistance of the pump is further reduced, and the speed of the pump can be increased. .

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an external perspective view of a bellows pump according to one embodiment of the present invention. The bellows pump comprises cylindrical cylinder portions 1a and 1b coaxially connected and arranged and these cylinder portions 1a and 1b.
Housings 3a and 3b are provided, in which cylinder heads 2a and 2b arranged on the outside in the axial directions of a and 1b are integrated. A pump head (not shown) is disposed inside the joint between the housings 3a and 3b. The pump head is connected to a suction port 4 and a discharge port 5 for a liquid to be transferred. I have. Air supply ports 6a, 6b for supplying gas, for example, air for reciprocating the bellows mounted therein are provided on the side surfaces of the cylinder heads 2a, 2b. The outside of the cylinder heads 2a, 2b is covered by head covers 7a, 7b.

FIG. 2 is a longitudinal sectional view showing the internal structure of the bellows pump. Inside the joint between the housings 3a and 3b, a disk-shaped pump head 11 made of PTFE or the like is arranged coaxially with the cylinder portions 1a and 1b. On both sides of the pump head 11, a pair of bottomed cylindrical bellows 12a, 12b formed of PTFE or the like, each of which can expand and contract in the axial direction, are arranged so that their opening sides face each other. 13a, 13b
Are formed respectively. These bellows 12a, 12b
Is composed of annular mounting portions 14a, 14b, disc-shaped movable plates 15a, 15b at the bottom, and bellows-shaped expanding and contracting portions 16a, 16b for integrally connecting these. Annular mounting part 1
4a and 14b are provided with a two-step groove 14 on the outer peripheral side of the front end face.
c is formed, and an inner screw 14d is formed on the inner periphery. On the other hand, mounting parts 14a, 14
a two-stage protrusion 11a fitted into the groove 14c on the front end face of
An outer screw 11b screwed with the inner screw 14d is formed. Both are connected by an inner screw 14d and an outer screw 11b, and a liquid seal is formed by the groove 14c and the protrusion 11a. The pump head 11 has suction-side valve units 16a and 16b that alternately open and close suction ports 18 communicating with the liquid suction port 4, and a discharge side that alternately opens and closes discharge ports 19 that communicate with the discharge port 5 of the same liquid. Valve units 17a and 17b are mounted.

The cylinder portions 1a, 1b of the housings 3a, 3b
1b is coaxially arranged with respect to the bellows 12a, 12b so as to accommodate the pair of bellows 12a, 12b, respectively. Opening edge portions 1c, 1c are provided on the outer peripheral portions of the opening end portions of the cylinder portions 1a, 1b facing each other.
1d is formed. The inner diameter of the outer peripheral edges 1a, 1b is determined by the outer diameter of the pump head 11 and the bellows 12a, 12b.
b is set to a size compatible with the outer diameter of the mounting portions 14a and 14b. The end faces 1e and 1f formed on the inner peripheral base ends of the opening edges 1c and 1d are connected to the cylinder head 2 in FIG.
The joint between the pump head 11 and the bellows 12a, 12b is connected to the O-ring 20 for gas sealing by tightening the four PTFE stud bolts 9 connecting the overhangs 8a, 8b projecting outward from the a and 2b. Pinch from both sides. The opening edges 1c and 1d cover the outer peripheral side of the joint between the pump head 11 and the bellows 12a and 12b, and restrain the radial movement of these members. As shown in FIG. 1, the opening edges 11c and 11d are formed with a protrusion 1g and a recess 1h at one or a plurality of positions in the circumferential direction, and the protrusion 1g and the recess 1h are fitted. By doing so, positioning in the circumferential direction is performed.

The cylinder heads 2a and 2b of the housings 3a and 3b, together with the cylinders 1a and 1b, have air chambers 21a and 2 sealed outside the bellows 12a and 12b.
1b is formed. Holes 22a, 22b are formed in the cylinder head portions 2a, 2b along the center axis of the pump. Bearings 23a, 23b are mounted in the holes 22a, 22b, and the bearings 23a, 23b are provided along the pump axis. The pump shafts 24a and 24b are slidably inserted.
The gaps between the pump shafts 24a, 24b and the holes 22a, 22b are hermetically sealed by lip seals 25a, 25b. The ends of the pump shafts 24a, 24b on the bellows 12a, 12b side are connected to the movable plates 15a, 15b of the bellows 12a, 12b via mounting plates 31a, 31b.
Has been fixed. The opposite ends of the pump shafts 24a, 24b are connected to connecting plates 32a, 32b by bolts 33. The connecting plates 32a and 32b are connected to each other by bolts 35 via connecting shafts 34a and 34b at upper and lower positions outside the cylinder portions 1a and 1b. These connecting shafts 34a, 34b are accommodated in shaft covers 36a, 36b suspended between the cylinder heads 2a, 2b so as to be slidable in the axial direction. In the drawings, 37a and 37b are mounting plates 32.
Proximity sensors 38a and 38 for detecting the proximity of a and 32b
“b” is a liquid leakage sensor that detects liquid leakage in the air chambers 21a and 21b.

Next, the operation of the bellows pump according to this embodiment having the above-described configuration will be described. Air supply port 6a
, The pressure in the air chamber 21a increases, and the bellows 12a contracts. The contracting operation is performed by connecting the pump shaft 24a to the connecting plate 32a → the connecting shaft 3a.
4a, 34b → the connecting plate 32b → the power is transmitted to the bellows 12b via the pump shaft 24b, and the bellows 12b extends. With this operation, the suction-side valve unit 16a is closed, 16b is open, the discharge-side valve unit 17a is open,
7b is closed, the transfer liquid introduced into the pump chamber 13a is discharged from the discharge port 5 through the valve unit 17a and the discharge port 19, and the pump chamber 13b has the suction port 4,
The transfer liquid is introduced through the discharge port 18 and the valve unit 16b. When the proximity sensor 37b detects the proximity of the mounting plate 31b, the air supply is stopped.

Subsequently, air is supplied to the air supply port 6b. As a result, the pressure in the air chamber 21b increases, so that the bellows 12b contracts. This contraction operation is performed by connecting the connecting plate 32b to the connecting shaft 34 from the pump shaft 24b.
a, 34b → the coupling plate 32a → the transmission to the bellows 12a via the pump shaft 24a, and the bellows 12a extends. With this operation, the suction side valve unit 16a opens,
16b is closed, discharge side valve unit 17a is closed, 17b
Is opened, the transfer liquid introduced into the pump chamber 13b is discharged from the discharge port 5 through the valve unit 17b and the discharge port 19, and the pump chamber 13a receives the suction port 4, the suction port 18, and the valve unit 16a. The transfer liquid is introduced via. When the proximity sensor 37a detects the proximity of the mounting plate 31a, the air supply is stopped. By repeating the above operation, a pump operation is realized.

According to the bellows pump of this embodiment, the pump head 11 and the mounting portions 14a, 14b of the bellows 12a, 12b are axially sandwiched between the opening end faces of the cylinder portions 1a, 1b of the housings 3a, 3b. Since the opening edges 1c and 1d are newly provided to restrain the radial movement of the pump head 11 and the bellows 12a and 12b, the desired sealing performance can be maintained for a long time, and the cylinder and the In addition to being integrated with the cylinder head, centering can be accurately performed. In addition, the fitting of the convex portion 1g and the concave portion 1h provided on the opening edge portions 1c and 1d allows the cylinder portions 1a and 1d to be fitted.
The position of b in the circumferential direction can also be accurately determined.

The lip seals 25a, 25b used for sealing the pump shafts 24a, 24b extend, for example, as shown in FIG. The seal piece 25d is formed integrally with the PT and is filled with a filler such as polyamide.
Use FE. Thereby, generation of abrasion powder can be suppressed as compared with the conventional rubber seal.

In order to increase the speed of the pump, the inside diameters of the suction port 18 and the discharge port 19 of the pump head 11 are made as large as possible, and the flow rate of the liquid introduced into the pump chambers 13a and 13b is reduced. And the pump chambers 13a, 13
By reducing the internal pressure b, the life of the pump can be improved and the speed of the pump can be increased.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a bellows pump according to one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the pump.

FIG. 3 is a sectional view of a lip seal used in the pump.

FIG. 4 is an external perspective view of a conventional bellows pump.

FIG. 5 is a vertical sectional view of the pump.

[Explanation of symbols]

1a, 1b: cylinder portion, 2a, 2b: cylinder head portion, 3a, 3b: housing, 4, 54: discharge port, 5,
55: suction port, 11, 51: pump head, 12a, 1
2b, 52a, 52b ... bellows, 13a, 13b, 6
5a, 65b: Pump chamber, 16a, 16b, 66a, 6
6b ... suction side valve unit, 17a, 17b, 67
a, 67b ... discharge side valve unit, 21a, 21b,
81a, 81b ... air chamber, 24a, 24b, 75a,
75b: pump shaft, 32a, 32b, 76a, 7
6b ... connecting plate, 34a, 34b, 77a, 77b ... connecting shaft, 52a, 52b ... cylinder, 53a, 53b
…cylinder head.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Go Watanabe 554, Fujikubo, Miyoshi-cho, Iruma-gun, Saitama Prefecture (72) Inventor Toshiki Onizuka 554, Fujikubo, Miyoshi-cho, Iruma-gun, Saitama Prefecture (72) Inventor Takashi Nojima 554, Fujikubo, Miyoshi-cho, Iruma-gun, Saitama F-term (reference) 3W075 BB14 BB17 3H077 AA01 CC03 CC07 CC17 DD15 EE21 EE22 EE26 FF09 FF22 FF45

Claims (6)

[Claims] 1. A disk-shaped pump head, and a bottomed cylinder which is provided on both sides of the pump head so that their opening sides face each other, and has pump chambers formed therein and which can be extended and contracted in the axial direction, respectively. A pair of bellows, and a cylinder that is coaxially arranged with respect to the bellows so as to house the pair of bellows therein, and that clamps the coupling portion between the pump head and the bellows at opposite ends. A pair of cylinders, each having a pair of cylinders, and a pair of cylinder heads respectively closing the openings of the pair of cylinders opposite to the pump head to form gas chambers outside the bellows together with the cylinders. A cylinder head connecting means for connecting the heads to each other; A pair of pump shafts penetrating airtightly and slidably along one end, and one end of each of which is connected to each bottom of the pair of bellows, and a shaft connection for connecting the other ends of the pair of pump shafts at a constant distance. A valve unit mounted on the pump head in the pump chamber to guide the transfer fluid from the suction port of the transfer fluid to the pump chamber and to guide the transfer fluid from the pump chamber to the discharge port of the transfer fluid; The bellows pump comprising: a bellows pump, wherein the cylinder has an opening edge portion that covers an outer peripheral side of a coupling portion between the pump head and the bellows. 2. The bellows according to claim 1, wherein the opposed ends of the pair of cylinders are formed with a convex shape and a concave shape with the other being concave. pump. 3. The bellows pump according to claim 1, wherein the cylinder and the cylinder head are integrally formed to form a housing. 4. The pair of cylinder head connecting means,
The bellows pump according to any one of claims 1 to 3, wherein the plurality of stud bolts are arranged around the cylinder in parallel with a center axis of the cylinder. 5. A plurality of shaft covers mounted between the cylinder heads in parallel with a center axis of the cylinder, and a plurality of shaft covers slidably accommodated in the shaft covers in the axial direction. The connecting shaft according to any one of claims 1 to 4, comprising: a connecting body that connects each end of the connecting shaft together with each other end of the pump shaft. Bellows pump. 6. The bellows pump according to claim 1, wherein a lip seal made of a fluororesin is attached to a portion of the cylinder head where the pump shaft slides.