JP2001020868A - Bellows pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bellows pump having an excellent performance of removing air and impurities. SOLUTION: A bellows 21 fixed at the tip of a drive shaft 3 is provided with a moving wall 22 driven in a reciprocating manner and a bellows part 23 having one end coupled to the moving wall 22 and the other end fixed at a fixed part and expanding and contracting along with reciprocating drive of the moving wall 22. The bellows is formed in a taper-form manner that a whole is gradually increased in an outside shape from the moving wall 22 side to the fixed part side. A pump chamber 26 consisting of the tip part of the bellows 21 and the recessed part 25 of a pump head 24 to contain the bellows is also formed in a tapered manner and stagnation of air and impurities is prevented from occurring.

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 chemical solution or the like by an expansion and contraction operation of a bellows.

[Prior art]

A bellows pump using a bellows made of Teflon (registered trademark) is known as a metering pump for transferring a chemical solution such as an acid by a predetermined amount in a semiconductor manufacturing apparatus. FIG. 4 is a sectional view showing a main part of the bellows pump. A drive shaft 3 is supported on the chassis 1 via a sliding ring 2 so as to be reciprocally movable. A movable wall 6 of a bellows 5 is fixed to a distal end of the drive shaft 3 via a connecting member 4. The bellows 5 of the bellows 5 has one end integrally connected to the movable wall 6 and the other end fixed between the chassis 1 and the pump head 8. The pump head 8 has bellows 5
Is formed, and the concave portion 9 and the movable wall 6 of the bellows 5 form a pump chamber 10. The lower end of the pump chamber 10 communicates with a suction port 12 of the transfer fluid via a suction valve 11, and the upper end of the pump chamber 10 communicates with a discharge port 14 of the transfer fluid via a discharge valve 13.

When the drive shaft 3 is reciprocated by driving means (not shown), the bellows portion 7 expands and contracts and the movable wall 6 reciprocates, so that the volume of the pump chamber 10 changes periodically. As a result, the transfer fluid is supplied from the suction port 12 to the suction valve 11 which is a check valve.
Through the pump chamber 10 and further into the pump chamber 10
The transfer fluid introduced into the inside is discharged from the discharge port 14 to the outside through a discharge valve 13 which is a check valve.

[0004]

However, in the above-mentioned conventional bellows pump, since many pits are formed in the bellows portion 7 of the bellows 5, air and impurities mixed with the transfer fluid enter the pits and become external. There is a structural problem that the air and impurities are not easily removed and the air and impurities are easily retained. In particular, in a semiconductor manufacturing apparatus, when contaminants are mixed in a silicon chip manufacturing process, a serious defect is caused in a product. In addition, mixing of air causes a decrease in pump performance.

[0005] The present invention has been made in view of the above problems, and has as its object to provide a bellows pump having excellent performance of removing air and impurities.

[0006]

A bellows pump according to the present invention has a movable wall reciprocatingly driven and one end connected to the movable wall and the other end fixed to a fixed portion. A bellows having a bellows portion which expands and contracts, a driving means for reciprocatingly driving the movable wall, a concave portion for accommodating the movable wall, and a pump chamber formed by the concave portion and an outer wall of the movable wall; A pump head that introduces a transfer fluid into the pump chamber from a suction unit disposed below the pump head and discharges the transfer fluid from a discharge unit disposed above the pump chamber. The bellows portion is a tapered bellows whose outer shape gradually increases from the movable portion side to the fixed portion side.

According to the present invention, since the bellows portion uses the tapered bellows whose outer shape gradually decreases from the fixed portion side to the movable portion side, the transfer fluid moves upward from the lower side of the pump chamber. In the process, air and impurities are easily removed, and it is possible to prevent stagnation at these bellows.
For this reason, it is possible to solve the problem that the discharge performance of the pump is improved and the accumulated matter flows to the outside during the operation of the pump and adversely affects the manufacturing process.

Further, according to the present invention, since the bellows is tapered, the discharge amount characteristics with respect to the discharge side load pressure are improved as compared with the diaphragm type and the parallel bellows type. That is, the effective diameter for receiving the pressure of the bellows decreases stepwise with respect to the load pressure on the discharge side, and discharge at a higher pressure than before becomes possible.

In order to more effectively prevent the accumulation of air and impurities, it is desirable that the suction part and the discharge part of the pump head are arranged so as to face the fixed part side of the bellows part.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a main part of a bellows pump according to one embodiment of the present invention. In FIG. 1, the same portions as those in FIG. 4 are denoted by the same reference numerals, and detailed description of the overlapping portions will be omitted. The main difference between the bellows pump of this embodiment and the conventional bellows pump shown in FIG.
The bellows 21 has a substantially conical movable wall 22 connected to the distal end of the drive shaft 3 via the connecting member 4, and the movable wall 22.
And a tapered bellows 23 whose base end is fixed between the chassis 1 and the pump head 24 and whose outer shape gradually increases from the front end to the base end. I have. The pump head 24 has a substantially conical recess 25 for accommodating the tip of the tapered bellows 21. Therefore, the pump chamber 26 formed by the bellows 21 and the recess 25 also has a substantially conical shape with a taper. Pump head 2
4, a main suction liquid passage 27 that vertically connects the suction valve 11 and the pump chamber 26 and a main discharge liquid passage 28 that vertically communicates the pump chamber 26 with the discharge valve 13 are formed. . Further, the pump head 24 has a suction liquid branch passage 31 communicating the main suction liquid passage 27 and the lowermost end of the pump chamber 26, and an uppermost end of the pump chamber 26 and the main discharge liquid passage 28.
And a discharge liquid branch passage 32 that communicates with the discharge liquid.

According to the bellows pump of this embodiment constructed as described above, since the transfer fluid introduced into the pump chamber 26 moves along the flow path obliquely upward, air and impurities are easily removed. Can be effectively prevented from staying. In particular, in this embodiment, in addition to the main suction liquid passage 27 and the main discharge liquid passage 28, the suction liquid branch passage 31 and the discharge liquid branch passage 32 face the base end side (the largest diameter side) of the bellows 21. Provided, the transfer fluid is pump chamber 2
6 will move from the lower end to the upper end. For this reason,
There is no place where the liquid stays, so that the air and impurities are more easily removed.

FIG. 2 is a graph showing the change in the discharge amount of the pump with respect to the load pressure on the discharge side between the embodiment product and the conventional product. When a conventional parallel bellows is used and when a spherical diaphragm is used, the discharge flow rate becomes zero at a load pressure of about 5 kg / cm ² , but the tapered bellows 2
In this example using No. 1, the discharge amount did not become 0 even when the load pressure exceeded 8 kg / cm ² . This is because the tapered bellows 21 reduces the effective diameter for receiving the load pressure stepwise with respect to the load pressure. That is, at high pressure, the portion of the bellows portion 23 having the smallest diameter mainly operates, at medium pressure, the portion having the smallest diameter of the bellows portion 23 and the portion having the next largest diameter mainly operate, and at low pressure, the most portion of the bellows portion 23 operates. The part from the small diameter part to the largest diameter part operates. As described above, according to the bellows pump of this embodiment, the discharge force characteristic with respect to the load pressure can be significantly improved as compared with the conventional one.

FIG. 3 is a diagram showing a cross section of a main part of a bellows pump according to another embodiment of the present invention. In this embodiment, instead of providing a branch for the main passage in the pump head as shown in FIG. 1, the pump head 35 includes a main suction liquid passage 36 and a main suction liquid passage 36 directly connected to the lower end and the upper end of the pump chamber 26, respectively. A discharge liquid passage 37 is provided. In this embodiment, there is an effect that the removal of air and impurities is more effective than the previous embodiment.

[0014]

As described above, according to the present invention, since the bellows portion of the bellows uses a tapered bellows whose outer shape gradually increases from the movable portion side to the fixed portion side, the transfer fluid is pumped. In the process of moving from the lower side to the upper side of the chamber, air and impurities are easily released, and it is possible to prevent the stagnant portion at the bellows portion. For this reason, it is possible to solve the problem that the discharge performance of the pump is improved and the accumulated matter flows to the outside during the operation of the pump and adversely affects the manufacturing process.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of a bellows pump according to an embodiment of the present invention.

FIG. 2 is a diagram showing a discharge flow rate characteristic with respect to a load pressure of the pump of the embodiment in comparison with a conventional example.

FIG. 3 is a sectional view showing a main part of a bellows pump according to another embodiment of the present invention.

FIG. 4 is a sectional view showing a main part of a conventional bellows pump.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Chassis, 3 ... Drive shaft, 5, 21 ... Bellows, 6,
2 movable wall, 7, 23 bellows, 8, 24, 35 pump head, 9, 25 recess, 10, 26 pump chamber, 1
DESCRIPTION OF SYMBOLS 1 ... Suction valve, 12 ... Suction port, 13 ... Discharge valve, 14 ... Discharge port, 27,36 ... Main suction liquid passage, 28,37 ... Main discharge liquid passage, 31 ... Suction liquid branch passage, 32 ... Discharge liquid branch Road.

Claims (2)

[Claims] A movable bellows reciprocatingly driven, a bellows having one end connected to the movable wall and the other end fixed to a fixed portion, and having a bellows portion which expands and contracts with the reciprocation of the movable wall; A reciprocating drive means, and a concave portion in which the movable wall is housed. The concave portion and the outer wall of the movable wall form a pump chamber, and the pump is moved from a suction portion disposed below the pump chamber. A pump head that introduces a transfer fluid into a chamber and discharges the transfer fluid from a discharge unit disposed above the pump chamber. The bellows of the bellows gradually moves from the movable unit side to the fixed unit side. A bellows pump characterized in that it is a tapered bellows whose outer shape becomes larger. 2. The bellows pump according to claim 1, wherein the pump head is arranged so that the suction part and the discharge part face the fixed part side of the bellows part.