JPH1054368A - Bellows pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bellows pump realizing high accurate fixed flow rate property. SOLUTION: A pump has a plurality of pump chambers 13a, 13b respectively having bellows 17a, 17b advancingly/retreatingly moved in an axial direction. The pump has an inflow side flow path guiding a liquid in a liquid storage tank to the pump chambers 13a, 13b when the bellows 17a, 17b are retreatingly moved, delivery side flow path guiding a liquid in the pump chambers 13a, 13b to a delivery nozzle when the bellows 17a, 17b are advancingly moved and a check valve provided respectively in each inflow side flow path and delivery side flow path. Further, the pump has electric motor 2a, 2b which can each independently drive the bellows 17a, 17b, by these motors 2a, 2b, a moving amount of the bellows 17a, 17b is controlled, a liquid amount flowing out from the delivery side flow path is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bellows pump capable of arbitrarily controlling a discharge amount, and more particularly to a technique which is effective when applied to the preparation of a processing chemical used in an electronic component manufacturing apparatus or the like.

[0002]

2. Description of the Related Art Conventionally, bellows pumps have been widely used as one of fixed-rate discharge pumps for supplying a predetermined amount of liquid.

This bellows pump obtains a suction pressure and a discharge pressure by making a bellows expand and contract.
The expansion and contraction of the bellows is generally controlled by a motor or air pressure. For example, in the liquid ejection apparatus disclosed in Japanese Patent Application Laid-Open No. 7-310838, the bellows is expanded and contracted by a combination of a motor and a ball screw. Further, Japanese Patent Application Laid-Open No. 62-23 / 1987
Japanese Patent Application Laid-Open No. H3-3858 discloses a bellows pump.
In the double-acting pump disclosed in Japanese Patent Publication No. 3 (1999), two bellows are alternately expanded and contracted by air pressure.

On the other hand, there has been proposed a type in which two pump chambers each having a bellows are juxtaposed in order to make the pump compact, such as a bellows pump disclosed in Japanese Patent Application Laid-Open No. 62-103489. In this case, each bellows is driven by two pneumatic cylinders arranged in parallel.

By the way, such a bellows pump is
It is often used in semiconductor manufacturing processes, taking advantage of the ability to supply a fixed amount of liquid at a relatively low pressure. For example,
It is used for applying a photoresist liquid to the surface of a semiconductor wafer as described in Japanese Patent Application Laid-Open No. 7-310838, and for preparing and supplying a processing chemical such as a cleaning liquid used in a semiconductor manufacturing process.

In this case, the photoresist solution is applied directly onto the semiconductor wafer via a bellows pump. On the other hand, the treatment liquid is prepared by supplying a constant amount of a chemical by a bellows pump into a container in which a predetermined amount of a base such as water is stored, and stirring this. And, the processing chemical liquid thus prepared is often supplied to a semiconductor manufacturing apparatus by a bellows pump.

[0007]

Here, in the semiconductor manufacturing process, in order to manufacture products continuously and efficiently, it is required that a processing chemical is always supplied at a constant flow rate to a semiconductor manufacturing apparatus. There are cases. in this case,
When preparing a treatment solution, it is necessary to constantly supply a constant amount of the drug as a raw material to the base, and furthermore, in order to keep the concentration constant, the amount of the drug to be sent must be strictly controlled. No.

However, in the case of a conventional bellows pump, a motor-driven pump as disclosed in Japanese Patent Application Laid-Open No. 7-310838 can provide a stable constant flow rate during the operation of the bellows, but the operation becomes intermittent and the constant amount is always obtained. It cannot be supplied.

On the other hand, in a pump using two bellows as disclosed in Japanese Patent Application Laid-Open No. Sho 62-103489 or the like, medicine can be continuously supplied by alternately operating the bellows. There are the following problems due to the pneumatic drive. That is, first, the movement of the bellows is affected by changes in the pressure and temperature of the air and the resulting change in sliding resistance, so that the flow rate is not constant. Second, due to the use of air pressure, it is difficult to instantaneously switch the bellows to start up to a predetermined operating speed in a short time, and the discharge flow becomes a pulsating flow. As described above, the pneumatic drive pump has a problem that it is difficult to obtain a highly accurate constant flow rate.

Further, in the pneumatically driven bellows pump, the bellows cannot be stopped in the middle of the stroke, so that the discharge amount is limited to an integral multiple of the amount discharged by one discharge operation, and fine discharge amount cannot be adjusted. There was also a problem. For this reason, the medicine supply amount cannot be precisely controlled, and stabilization has been an issue.

An object of the present invention is to provide a bellows pump which realizes a constant flow characteristic with high accuracy without pulsation.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0013]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

That is, the bellows pump of the present invention has a bellows which moves forward and backward in the axial direction, and has a plurality of pump chambers which generate suction pressure and discharge pressure by the expansion and contraction of the bellows. In addition, the pump chamber communicates with the liquid storage tank, and when the bellows moves backward, the inflow-side flow path guides the liquid in the liquid storage tank to the pump chamber. It has a discharge-side flow path for guiding the liquid in the pump chamber to the discharge nozzle during movement, and a check valve provided in each of the inflow-side flow path and each of the discharge-side flow paths. Further, there is provided an electric drive device capable of independently driving the bellows, and the amount of liquid flowing out from the discharge side flow path is controlled by controlling the amount of movement of the bellows by the electric drive device. And

In this case, each of the electric driving devices has an electric motor, a screw member connected to the motor, and a driving member screwed to the screw member and connected to the bellows. The bellows may be moved forward and backward by driving the driving member in the axial direction by rotation of the motor. In the present application, the rotation of the motor means a forward / reverse operation of the motor including a displacement of 360 degrees or more.

Further, the amount of liquid flowing out of the discharge side flow path is controlled to be constant by making the above-mentioned two pump chambers into two and making the two pump chambers perform a discharging operation alternately by the above-mentioned electric driving device. You may do it.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view showing an appearance of a bellows pump according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line AA, and FIG. 3 is a cross-sectional view taken along line BB. . The bellows pump of the present invention always supplies a constant amount of medicine by arranging two electric bellows side by side and optimally controlling them, and the present embodiment relates to a process used in a semiconductor manufacturing process. The bellows pump of the present invention is applied to the preparation of a medical solution.

As shown in FIG. 1, the bellows pump according to the present embodiment includes a motor housing 1m for housing an electric driving device such as a motor, a pump housing 1p in which the bellows pump is formed, and a suction and discharge of a medicine. And a medicine storage tank (liquid storage tank) 31 and a medicine supply nozzle (liquid ejection nozzle).
32. And among them, Figure 2
As shown in FIG. 2, the electric bellows A and the electric bellows B are stored in such a manner that they can operate independently. In the following description, the suffixes a and b of the reference numerals indicate members belonging to the electric bellows A and B, respectively.

Here, FIG.
As shown in FIG. 2, two servomotors (hereinafter abbreviated as motors) 2a and 2b are stored, and couplings 3a and
The ball screw (screw member) 4a, 4b is connected by 3b. Nuts 7a, 7b fixed to drive shafts (drive members) 5a, 5b and mounted on linear guides 6a, 6b are screwed to the ball screws 4a, 4b. Therefore, in the bellows pump, the motors 2a,
2b rotates the ball screws 4a and 4b, and accordingly, the drive shafts 5a and 5b move the linear guides 6a and 6b.
2 and advance and retreat in the left-right direction in FIG.

The motor 2 of the ball screws 4a, 4b
a, 2b side is a bearing 9 attached to the support wall 8;
a and 9b rotatably supported. further,
Encoders 10a and 10b are attached to the motors 2a and 2b, respectively, so that their rotation angles and rotation speeds can be accurately measured. In this embodiment, the rotational motion of the motors 2a, 2b is controlled by the drive shafts 5a, 5b.
Although the example in which the ball screws 4a and 4b are used as the screw members in order to convert the linear motion into the linear motion is shown, a slide screw such as a trapezoidal screw or the like may be used.

Next, the pump housing 1p is provided with a connecting plate 11 made of synthetic resin and polytetrafluoroethylene (PTF) which is a fluorine resin in consideration of corrosion resistance due to chemicals.
Pump block 12 formed of a synthetic resin such as E)
It is composed of As shown in FIGS. 2 and 3, pump chambers 13a and 13b
And the inflow side flow paths 14a, 14b and the discharge side flow path 15a,
15b are formed, through which the medicine flows.

In the pump chambers 13a and 13b, bellows 17a and 17b are formed integrally with the end plates 16a and 16b. In this case, the tips 18a, 18b of the bellows 17a, 17b
Is connected to the tips of the drive shafts 5a and 5b. Accordingly, the bellows 17a, 17b also expand and contract in the pump chambers 13a, 13b due to the advance and retreat of the drive shafts 5a, 5b accompanying the rotation of the motors 2a, 2b, and move forward and backward in FIG. Thus, the pump chambers 13a, 13
The pressure for inhaling / discharging the medicine is generated in the bellows 17a and 17b and the end plate 16
a and 16b are also made of a fluorine resin or the like for corrosion resistance. Also, O-rings 19a, 19b are attached to side portions of the end plates 16a, 16b. For this reason, the pump chambers 13a and 13b
The motor housing 1m is air-tightly isolated from the motor housing 1m by the end plates 7a and 17b and the end plates 16a and 16b.

On the other hand, the valve housing 1v is provided with an inflow side block 2 mounted on the upper and lower sides of the pump housing 1p.
0 and a discharge-side block 21, each of which is formed of a synthetic resin such as a fluororesin. Here, an inflow-side flow path 22 and a discharge-side flow path 23 are formed inside each of them, and the medicine supply nozzle 32 of the medicine storage tank 31 or the treatment liquid supply tank 33 is connected via an external tube 24. It is connected. Also, as shown in FIG. 3, these are internally branched into two branches (22a, 22a).
b and 23a, 23b), the inflow-side flow paths 14a, 14b and the discharge-side flow paths 15a, 15a, of the pump housing 1p, respectively.
15b. Therefore, the bellows 17a, 1
7b moves backward, the inflow side flow paths 14a, 14b
As a result, the liquid in the medicine storage tank 31 is displaced by each pump chamber 13a,
When the bellows 17a, 17b move forward, the medicine in each pump chamber 13a, 13b is guided to the medicine supply nozzle 32.

The processing chemical supply tank 33 is provided with a base supply pipe 34 to which water or the like serving as a base of the processing chemical is supplied.
A processing chemical supply pipe 35 for feeding the prepared processing chemical to a semiconductor manufacturing apparatus (not shown) is provided. Then, a predetermined chemical is supplied from the chemical supply nozzle 32 in a constant amount, whereby a processing chemical solution having a constant concentration is created and supplied to the semiconductor manufacturing apparatus. In addition, as a method of preparing the processing chemical, the processing chemical may be continuously prepared by constantly supplying the base from the base supply pipe 34, or a certain amount of the base may be supplied to the processing chemical supply tank 33. , And a certain amount of the treatment liquid may be prepared.

By the way, inflow-side check valves 25a and 25b and discharge-side check valves 26a and 26b are formed in the inflow-side flow paths 14a and 14b of the pump housing 1p and the discharge-side flow path 23 of the valve housing 1v. In each case, the medicine flows only in one direction. Here, the structure will be described taking the check valve 25a as an example. Each check valve has the same structure.

This check valve 25a, as shown in FIG.
It is arranged between the pump block 12 and the lower block 36 provided on the inflow side block 20. A valve housing chamber 28 is formed in the pump block 12 to house a spherical valve element 27 having a diameter R movably in the vertical direction. The lower end of the valve storage chamber 28 communicates with a flow passage 29 formed in the lower block 36. The flow passage 2
Reference numeral 9 also communicates with the inflow-side passage 22a of the inflow-side block 20.

On the other hand, the inner diameter of the flow passage 29 is
Is set to be smaller than the diameter R. Therefore, when the valve element 27 is located at the position shown by the solid line in FIG.
9 will be closed by the valve body 27. On the other hand, when the valve body 27 moves to the upper part along the valve accommodating chamber 28 and is raised to the position shown by the dashed line in FIG. 4, the flow passage 29 opens and the inflow side flow passage 22a and the inflow side flow passage 14a Communicates with

As described above, when the bellows 17a retreats and a suction pressure is generated in the pump chamber 13a, the valve body 27 is raised, the valve is opened, and the medicine flows in from the inflow-side flow path 22a. Further, when the bellows 17a moves forward and a discharge pressure is generated in the pump chamber 13a, the valve 27 closes the flow passage 29 and the valve closes, and the backflow of the drug to the inflow-side flow passage 22a is reversed, as opposed to at the time of suction. Hindered. Conversely, the discharge-side check valve 26a closes when a suction pressure is generated in the pump chamber 13a, and opens when a discharge pressure is generated. Therefore, the suction and discharge of the medicine are controlled by the inflow side check valve 25a and the discharge side check valve 26a in the electric bellows A, and by the inflow side check valve 25b and the discharge side check valve 26b in the electric bellows B. You.

Next, a description will be given of a pump control method in the case where a medicine is supplied using the bellows pump having such a configuration.

FIG. 5 is a flowchart showing an example of a control pattern of the bellows pump. FIG. 5 shows the operating speed of the electric bellows A (hereinafter abbreviated as bellows A), the operating speed of the electric bellows B (hereinafter abbreviated as bellows B), and the flow rate of the medicine discharged from the bellows pump on the vertical axis. , And the time T represents the control pattern of the bellows pump on the horizontal axis.

[0031] First of all, to operate the bellows A at time t _1. That is, the motor 2a is driven to move the drive shaft 5a to move the bellows 17a forward (to the left in FIG. 2). Thus, the medicine in the pump chamber 13a starts to be discharged. At this time, since the bellows 17a is raised to stretch velocity V _1, as shown at the bottom of FIG. 5, the discharge flow rate rises suddenly at time t ₁ to the flow rate Q.

Next, operate the bellows B in some slow time t ₂ from time t _1. That is, the motor 2b is driven to move the drive shaft 5b to move the bellows 17b backward (to the right in FIG. 2). Thereby, the medicine starts to be sucked into the pump chamber 13b. At this time, the bellows 17b is to be operated at a faster rate V ₂ than the bellows 17a, drug inhalation is terminated before the medicine ejection from the bellows A is completed (time t _3). Then, when the ejection of the medicine from the bellows A ends at time t ₄ , the bellows A
On behalf of the bellows B on standby from time t ₃ to time t ₄ is operated to the medicine discharge side, to expel medicament from the pump chamber 13b. At this time, since the change from the bellows A to the bellows B is performed instantaneously, the discharge flow rate from the pump is maintained constant.

On the other hand, after the bellows for ejecting drug was replaced, the bellows A, similar to the previous bellows B, the intake of the drug is performed from time t ₅ toward t _6. And
When the medicine ejection of the bellows B is completed at time t _7, again bellows A around the discharge side, to maintain the discharge flow rate constant.

As described above, in the bellows pump, it is possible to always maintain a constant discharge flow rate from the pump by using the rising performance of the electric bellows and alternately using two of them.

FIG. 6 shows another example of the control pattern of the bellows pump. FIG. 6 also has the same configuration as FIG.

The control pattern shown in FIG. 6 is similar to that shown in FIG. 5 in that the bellows A and the bellows B alternately eject the medicine. The operation speed control of the bellows A and B is characteristic. That is, the bellows A starts ejecting the drug at a velocity V ₁ at time t _11, the bellows B is at a speed V ₂ at time t ₁₂ to the point where start drug intake is the same as that of FIG. However, in the control pattern, the bellows A is gradually decelerated from the speed V ₁ toward t ₁₄ the operating speed from the time t ₁₃ to 0.
On the other hand, the bellows B is the same time a reduction of the bellows A, the operating speed gradually accelerated from 0 to the speed V _1. At this time, the discharge flow rate from both bellows A and B changes as shown by the dotted line in FIG. 6, but the total amount is always maintained at Q. In other words, the electric bellows is controlled so as to always maintain a constant discharge flow rate from the pump by utilizing the characteristic that the speed control is accurate and easy. In this case, since there is no sudden rise or fall as shown in FIG. 5, and a small transient phenomenon existing when the bellows A and B are driven can be absorbed, a more stable discharge flow rate can be obtained. Can be obtained.

Although the invention made by the inventor has been specifically described based on the embodiment, the invention is not limited to the embodiment and can be variously modified without departing from the gist of the invention. Needless to say,

For example, in the above-described embodiment, an example is shown in which servo motors are used as the motors 2a and 2b. However, any motor that can accurately control the rotation angle, such as a stepping motor or an ultrasonic motor, is used. Any type of motor may be used. Further, the structure of the check valve is not limited to the above-described one, and any structure such as one that moves the valve body using magnetism can be adopted. Further, the number of pump chambers is not limited to two, and a larger number of pump chambers may be appropriately controlled.

In the above description, the case where the invention made by the present inventor is mainly applied to the preparation of a processing chemical solution used in a semiconductor manufacturing process, which is a field of application, has been described. However, the present invention is not limited to this. For example, the present invention can be used to supply the prepared processing chemical liquid to a semiconductor manufacturing apparatus, and can also be applied to a manufacturing process of a precision machine or another electronic component.

[0040]

Advantageous effects obtained by typical ones of the inventions disclosed in the present application will be briefly described.
It is as follows.

(1) Since the operation speed and the movement amount of the bellows can be electrically controlled, the discharge amount can be arbitrarily and precisely controlled. That is, various operation controls, such as alternately operating the two bellows and stopping the bellows accurately during the stroke, are possible, and the discharge amount can be set freely. Therefore, it is possible to obtain characteristics that cannot be realized by the conventional pneumatic operation, such as continuously discharging a constant flow rate without pulsation and discharging an arbitrary amount by an intermittent operation.

(2) Since the electric drive device is employed, the bellows contributing to the discharge can be instantaneously switched, and there is an effect that there is little pulsation when the bellows are switched. In addition, since the flow rate can be arbitrarily changed in the middle, the discharge operation can be performed with the bellows overlapped, whereby the pulsation can be further reduced.

[Brief description of the drawings]

FIG. 1 is a plan view showing the appearance of a bellows pump according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a sectional view showing a configuration of a check valve used in the bellows pump of FIG. 1;

FIG. 5 is a time chart showing a control example of the bellows pump of FIG. 1;

FIG. 6 is a time chart showing another control example of the bellows pump of FIG. 1;

[Explanation of symbols]

 1m Motor housing 1p Pump housing 1v Valve housing 2a Motor 2b Motor 3a Coupling 3b Coupling 4a Ball screw (screw member) 4b Ball screw (screw member) 5a Drive shaft (drive member) 5b Drive shaft (drive member) 6a Linear guide 6b Linear guide 7a Nut 7b Nut 8 Support wall 9a Bearing 9b Bearing 10a Encoder 10b Encoder 11 Connection plate 12 Pump block 13a Pump chamber 13b Pump chamber 14a Inflow side flow path 14b Inflow side flow path 15a Discharge side flow path 15b Discharge side flow path 16a End plate 16b End plate 17a Bellows 17b Bellows 18a Tip 18b Tip 19a O-ring 19b O-ring 20 Inflow-side block 21 Discharge-side block 22 Inlet-side flow path 22a Inflow-side flow path 22b Inflow-side flow path 23 Discharge-side flow path 23a Discharge-side flow path 23b Discharge-side flow path 24 Tube 25a Inflow-side check valve 25b Inflow-side check valve 26a Discharge-side check valve 26b Discharge side check valve 27 Valve element 28 Valve storage chamber 29 Flow passage 31 Drug storage tank (liquid storage tank) 32 Drug supply nozzle (liquid discharge nozzle) 33 Treatment chemical supply tank 34 Base supply pipe 35 Treatment chemical supply pipe 36 Lower block A Electric bellows B Electric bellows

Claims (3)

[Claims] 1. A plurality of pump chambers each having a bellows that moves forward and backward in the axial direction, and generates a suction pressure and a discharge pressure by expansion and contraction of the bellows, and communicates with each of the pump chambers and a liquid storage tank. An inflow-side flow path that guides the liquid in the liquid storage tank to the pump chamber when the bellows moves backward, and communicates with each of the pump chambers and the liquid discharge nozzle, and the liquid inside the pump chamber when the bellows moves forward. A discharge-side flow path that guides the discharge nozzle, a check valve provided in each of the inflow-side flow path and each of the discharge-side flow paths, and an electric drive device that can independently drive the bellows. A bellows pump, wherein the amount of liquid flowing out of the discharge-side flow path is controlled by controlling the amount of movement of the bellows by the electric drive device. 2. The bellows pump according to claim 1, wherein each of the electric driving devices is an electric motor, a screw member connected to the motor, and screwed to the screw member and connected to the bellows. A bellows pump comprising: a driving member that is driven by the motor and drives the driving member in an axial direction by rotation of the motor to move the bellows forward and backward. 3. The bellows pump according to claim 1, wherein the bellows pump has two pump chambers, and the electric driving device alternately discharges the pump chambers to the two pump chambers. The bellows pump controls the amount of liquid flowing out of the discharge-side flow path to be constant by performing the operation.