Pump device and fluid discharge quantity control method

Abstract

This pump device comprises a pump chamber 120 in which an expansion / contraction part 126 is accommodated, a piston part 17 that expands and contracts the expansion / contraction part 126 to discharge a fluid from the pump chamber 120, and a control device. The piston part 17 has a first cylinder chamber 130, a second cylinder chamber 140 arranged between the first cylinder chamber 130 and the pump chamber 120 and having a larger volume than the first cylinder chamber 130, a first piston 131 accommodated so as to be capable of reciprocating movement along the arrangement direction, and a second piston 141 accommodated so as to be capable of reciprocating movement along the arrangement direction, alone or in tandem with the first piston 131. The control device controls the discharged quantity of fluid by switching operation modes between a first operation mode in which fluid is discharged from the pump chamber 120 in a first discharge quantity and a second operation mode in which the fluid is discharged from the pump chamber 120 in a second discharge quantity that is greater than the first discharge quantity.

Description

Pump device and fluid discharge amount control method

[0001] The present invention relates to a pump device and a method for controlling a fluid discharge amount.

[0002] Conventionally, in semiconductor manufacturing processes and the like, cleaning of workpieces such as wafers is performed by immersing the workpieces in a cleaning tank containing a cleaning liquid. Patent Document 1 discloses a pump that replenishes a cleaning tank with a chemical liquid stored in a tank. In the pump of Patent Document 1, a piston is moved by air supplied from an air supply port, and a bellows connected to the piston moves in an expanding and contracting manner. The expansion and contraction of the bellows supplies a predetermined amount of chemical liquid to the cleaning tank.

[0003] Japanese Patent Application Publication No. 11-257236

[0004] The pump in Patent Document 1 is provided with a dial for adjusting the amount of expansion and contraction of the bellows. A user operates this dial to adjust the discharge rate, which is the amount of medicinal liquid discharged from the pump.

[0005] However, the pump in Patent Document 1 does not discharge the liquid chemical by switching the discharge rate between two or more different preset discharge rates, making it difficult to supply the desired total discharge rate of the liquid chemical in a short period of time.

[0006] In one embodiment, the pump device includes a pump chamber that accommodates an extension / contraction section, a piston section that extends and contracts the extension / contraction section to discharge fluid from the pump chamber, and a control device that controls a supply of working air to the piston section to control a discharge amount of fluid discharged from the pump chamber. The piston section includes a first cylinder chamber, a second cylinder chamber arranged between the first cylinder chamber and the pump chamber and having a larger volume than the first cylinder chamber, a first piston accommodated in the first cylinder chamber so as to be reciprocal along an arrangement direction in which the first cylinder chamber and the second cylinder chamber are arranged, and a second piston accommodated in the second cylinder chamber so as to be reciprocal along the arrangement direction together with the first piston or independently, wherein a stroke of the second piston is longer than that of the first piston, and one end of the second piston is connected to the extension / contraction section and the other end is movable in contact with and away from the first piston. The control device controls the fluid discharge rate by switching between an operating mode between a first operating mode in which operating air is supplied to the first cylinder chamber, the first piston and the second piston are moved together along the arrangement direction, and fluid is discharged from the pump chamber at a first discharge rate, and a second operating mode in which operating air is supplied to the second cylinder chamber, the second piston is moved independently along the arrangement direction, and fluid is discharged from the pump chamber at a second discharge rate that is greater than the first discharge rate.

[0007] In one embodiment, a fluid discharge rate control method uses a pump device including a pump chamber that accommodates an extension / contraction section, a first cylinder chamber that accommodates a first piston, and a second cylinder chamber that accommodates a second piston arranged between the pump chamber and the first cylinder chamber and that has a longer stroke than the first piston. The fluid discharge rate control method controls the fluid discharge rate by switching between an operating mode between a first operating mode in which operating air is supplied to the first cylinder chamber, the first piston and the second piston are moved together along an arrangement direction in which the first cylinder chamber and the second cylinder chamber are arranged, and the extension / contraction section is extended and retracted to discharge fluid from the pump chamber at a first discharge rate, and a second operating mode in which operating air is supplied to the second cylinder chamber, the second piston is moved independently along the arrangement direction, and the extension / contraction section is extended and retracted to discharge fluid from the pump chamber at a second discharge rate that is greater than the first discharge rate.

[0008] According to the present invention, it is possible to discharge fluid from a single pump device by switching between a first discharge rate and a second discharge rate that is greater than the first discharge rate.

[0009] Fig. 1 is a block diagram schematically showing the general configuration of a pump device according to an embodiment; Fig. 2 is a cross-sectional view of a pump unit included in the pump device; Fig. 3 is a cross-sectional view of the pump unit when the pump device is operating in a first operation mode; Fig. 4 is a cross-sectional view of the pump unit when the pump device is operating in a second operation mode; Fig. 5 is a timing chart of the discharge and suction of fluid until a total discharge liquid volume is reached; and Fig. 6 is a flowchart illustrating the processing flow in a fluid discharge volume control method.

[0010] A pump device according to an embodiment of the present invention will now be described in detail with reference to the drawings. The pump device according to the present embodiment can be used, for example, in a semiconductor manufacturing process, in a step of replenishing a chemical solution in a chemical solution tank of a semiconductor manufacturing device.

[0011] <Overall Configuration> Fig. 1 is a block diagram showing a schematic configuration of a pump device 1. The pump device 1 includes a pump unit 10 and a control device 11. The dashed lines in Fig. 1 indicate signal lines. The pump unit 10 is controlled by the control device 11 to draw in a chemical solution stored in a tank 30 and discharge the drawn-in chemical solution into a chemical solution tank 31. The pump unit 10 includes a housing 12, a piston unit 17, valves 20, 22, and 23, and sensors 24, 25, 26, and 27. The piston unit 17 includes a first cylinder unit 13 and a second cylinder unit 14.

[0012] Valves 20, 22, and 23 are, for example, solenoid valves, and their operations are controlled by control device 11. Sensors 24, 25, 26, and 27 are, for example, magnetic sensors. Sensors 24 and 25 detect the position of a first piston (described later) housed in first cylinder portion 13 and output a detection signal to control device 11. Sensors 26 and 27 detect the position of a second piston (described later) housed in second cylinder portion 14 and output a detection signal to control device 11.

[0013] <Pump Unit 10> FIG. 2 is a cross-sectional view of the pump unit 10. Note that FIG. 2 shows a cross-sectional view of the pump unit 10 in an initial state in which the pump unit 10 is not operating. In the pump unit 10, the housing 12 and piston unit 17 are arranged in series along the axis X via a mounting block 15. In the piston unit 17, the first cylinder unit 13 and the second cylinder unit 14 are arranged in series along the axis X. Specifically, the second cylinder unit 14 is disposed between the housing 12 and the first cylinder unit 13. More specifically, the housing 12 and the second cylinder unit 14 are connected to each other via the mounting block 15. Note that in the following description, a direction parallel to the axis X is referred to as the "arrangement direction," a direction from the second cylinder unit 14 toward the first cylinder unit 13 along the arrangement direction is referred to as the "first direction A1," and a direction from the second cylinder unit 14 toward the housing 12 along the arrangement direction is referred to as the "second direction A2."

[0014] <Housing 12> The housing 12 is a hollow, bottomed, cylindrical member in which a pump chamber 120 is formed, with an open end on the first direction A1 side. An intake port 121 and an outlet port 122 are provided on the outer peripheral wall surface of the housing 12 on the second direction A2 side. The intake port 121 communicates with the pump chamber 120 and the outside via an intake flow path 124 provided with a check valve 123. The check valve 123 prevents fluid from being discharged from the intake port 121 when the pump chamber 120 becomes positive pressure. The outlet port 122 communicates with the pump chamber 120 and the outside via an outlet flow path 128 provided with a check valve 125. The check valve 125 prevents fluid from being drawn into the pump chamber 120 through the outlet port 122 when the pump chamber 120 becomes negative pressure.

[0015] Instead of the check valves 123 and 125, a solenoid valve that opens and closes the flow path by an electric signal, a motor-driven valve, or an air-operated valve that operates by air pressure may be used.

[0016] The pump chamber 120 accommodates an expansion / contraction section 126. The expansion / contraction section 126 is, for example, a bellows or a diaphragm, and is arranged with the axis X as its central axis. The expansion / contraction section 126 can expand and contract along the arrangement direction. In the following description, a case where a bellows is used as the expansion / contraction section 126 will be described as an example. The expansion / contraction section 126 has a closed end 126a, an opening periphery 126b, and a bellows section 126c.

[0017] The closed end 126a has a shape that protrudes in the second direction A2, and a second piston 141 (described later) is attached to the first direction A1 side of the closed end 126a. Specifically, a mounting hole 126d having an internal thread is formed on the first direction A1 side of the closed end 126a, centered on the axis X. An end 143a of the second direction A2 side of the second piston 141 (described later) is fastened to the mounting hole 126d by threaded connection.

[0018] The opening periphery 126b is formed at the end on the first direction A1 side. The expandable portion 126 is fixed to the housing 12 and the mounting block 15 at the opening periphery 126b. Specifically, the opening periphery 126b is sandwiched between a mounting portion 127 formed at the end on the first direction A1 side of the housing 12 and a mounting portion 151 formed on the mounting block 15, thereby fixing the expandable portion 126 to the housing 12.

[0019] The bellows portion 126c is formed between the closed end portion 126a and the opening peripheral portion 126b. When the second piston 141 attached to the closed end portion 126a moves in the second direction A2, the bellows portion 126c expands in the second direction A2. When the second piston 141 moves in the first direction A1, the bellows portion 126c contracts in the first direction A1.

[0020] <Mounting block 15> The mounting block 15 is a cylindrical member having an insertion hole 150 formed therein and centered on the axis X. As described above, the mounting block 15 is connected to the housing 12 at its end on the second direction A2 side, and to the second cylinder portion 14 at its end on the first direction A1 side. A rod portion 143 of a second piston 141 (described later) is inserted into the insertion hole 150 so as to be able to reciprocate along the arrangement direction. <Piston portion 17> The piston portion 17 has a first cylinder portion 13, a second cylinder portion 14, and an intermediate block 16 arranged at the boundary between the first cylinder portion 13 and the second cylinder portion 14.

[0021] <First Cylinder 13> The first cylinder 13 is a hollow, bottomed, cylindrical member in which a first cylinder chamber 130 is formed, the end of which is open on the second direction A2 side. The volume of the first cylinder chamber 130 is, for example, 5 ml. However, the volume of the first cylinder chamber 130 is not limited to the above value. A first piston 131 is disposed in the first cylinder chamber 130 so as to be able to reciprocate along the arrangement direction.

[0022] The first piston 131 is formed by a head portion 132 and a rod portion 133. The head portion 132 has a diameter centered on the axis X that is approximately equal to the inner diameter of the first cylinder portion 13. A groove 132a is formed along the outer periphery of the outer wall surface of the head portion 132, and a sealing member 134, such as an O-ring, is provided in the groove 132a. The head portion 132 may be made of a metal material so that its position within the first cylinder chamber 130 can be detected by the sensors 24 and 25, which are magnetic sensors. Alternatively, if the head portion 132 is not made of a metal material, a magnetic material may be attached to a portion of the head portion 132.

[0023] The rod portion 133 is formed in a rod shape extending along the arrangement direction with the axis X as its center. One end of the rod portion 133 (i.e., the first direction A1 side) is connected to the head portion 132. The vicinity of the other end of the rod portion 133 (i.e., the second direction A2 side) is inserted into an insertion hole 160 formed in the intermediate block 16, which will be described later.

[0024] A first supply / discharge port 135, an exhaust port 136, and sensors 24 and 25 are provided on the side wall of the first cylinder portion 13. The first supply / discharge port 135 is an opening formed on the side wall of the first cylinder portion 13 on the first direction A1 side, and connects the outside of the first cylinder portion 13 with the first cylinder chamber 130. The first supply / discharge port 135 is connected to the valve 20 via piping 200 (see FIG. 1 ). When the valve 20 operates in accordance with the control of the control device 11, working air, which is a fluid such as compressed air, is supplied to the first cylinder chamber 130 or air is exhausted from the first cylinder chamber 130 via the first supply / discharge port 135. The working air that flows in via the first supply / discharge port 135 is supplied to the first cylinder chamber 130 on the first direction A1 side relative to the head portion 132.

[0025] The exhaust port 136 is an opening formed on the second direction A2 side of the side wall of the first cylinder portion 13, and connects the outside of the first cylinder portion 13 with the first cylinder chamber 130. Air in the first cylinder chamber 130 that is closer to the second direction A2 than the head portion 132 is exhausted from the exhaust port 136 to the outside.

[0026] The sensor 24 is provided on the first direction A1 side of the side wall of the first cylinder portion 13. The sensor 24 detects, based on a change in the magnetic field, that the head portion 132 has approached the bottom surface 137 of the first cylinder portion 13 as the first piston 131 moves along the arrangement direction. When the sensor 24 detects that the head portion 132 has approached the bottom surface 137, it outputs a detection signal to the control device 11.

[0027] The sensor 25 is provided on the second direction A2 side of the side wall of the first cylinder portion 13. The sensor 25 detects, based on a change in the magnetic field, that the head portion 132 has approached the intermediate block 16 as the first piston 131 moves along the arrangement direction. When the sensor 25 detects that the head portion 132 has approached the intermediate block 16, it outputs a detection signal to the control device 11.

[0028] <Second Cylinder 14> The second cylinder 14 is a hollow, bottomed, cylindrical member that defines a second cylinder chamber 140 that is open at its end facing the first direction A1. An insertion hole 145 having a diameter smaller than the diameter of the opening at the end facing the first direction A1 is formed in a bottom surface 149 of the second cylinder 14. A rod 143 of a second piston 141, which will be described later, is inserted into the insertion hole 145. A groove 145a is formed along the inner periphery of the inner wall surface of the insertion hole 145, and an elastic member 148, such as a packing, is housed in the groove 145a.

[0029] The volume of the second cylinder chamber 140 is larger than the volume of the first cylinder chamber 130, for example, 40 ml. The volume of the second cylinder chamber 140 is not limited to the above value, but may be any value larger than the volume of the first cylinder chamber 130. In this case, the volume of the second cylinder chamber 140 is preferably at least twice the volume of the first cylinder chamber 130.

[0030] A second piston 141 is disposed in the second cylinder chamber 140 so as to be able to reciprocate along the arrangement direction. The second piston 141 is formed by a head portion 142 and a rod portion 143. The head portion 142 has a diameter centered on the axis X and substantially equal to the inner diameter of the second cylinder portion 14. A groove 142a is formed along the outer periphery of the outer wall surface of the head portion 142, and a sealing member 144, such as an O-ring, is provided in the groove 142a. The head portion 142 may be made of a metal material so that its position within the second cylinder chamber 140 can be detected by the sensors 26 and 27, which are magnetic sensors. Alternatively, if the head portion 142 is not made of a metal material, a magnetic material may be attached to a portion of the head portion 142.

[0031] The rod portion 143 is formed in a rod shape extending along the arrangement direction centered on the axis X, and its length is longer than the length of the rod portion 133 of the first piston 131. In other words, the stroke of the second piston 141 is longer than the stroke of the first piston 131. One end of the rod portion 143 (i.e., the first direction A1 side) is connected to the head portion 142. The rod portion 143 is inserted into an insertion hole 145 formed in the bottom surface 149 and an insertion hole 150 formed in the mounting block 15. As described above, the other end 143a of the rod portion 143 (i.e., the second direction A2 side) is threadedly coupled to the mounting hole 126d formed in the closed end 126a of the telescopic portion 126. In this way, the second piston 141 is attached to the telescopic portion 126.

[0032] A second supply / discharge port 146, a third supply / discharge port 147, and sensors 26 and 27 are provided on the side wall of the second cylinder portion 14. The second supply / discharge port 146 is an opening formed on the side wall of the second cylinder portion 14 on the first direction A1 side, and connects the outside of the second cylinder portion 14 with the second cylinder chamber 140. The second supply / discharge port 146 is connected to the valve 22 via piping 220 (see FIG. 1 ). When the valve 22 operates in accordance with the control of the control device 11, working air is supplied to or exhausted from the second cylinder chamber 140 via the second supply / discharge port 146. The working air that flows in via the second supply / discharge port 146 is supplied to the second cylinder chamber 140 on the first direction A1 side relative to the head portion 142.

[0033] The third supply / discharge port 147 is an opening formed on the second direction A2 side of the side wall of the second cylinder portion 14, and connects the outside of the second cylinder portion 14 with the second cylinder chamber 140. The third supply / discharge port 147 is connected to the valve 23 via piping 230 (see FIG. 1 ). When the valve 23 operates in accordance with the control of the control device 11, working air is supplied to the second cylinder chamber 140 or air is exhausted from the second cylinder chamber 140 via the third supply / discharge port 147. The working air that flows in via the third supply / discharge port 147 is supplied to the second cylinder chamber 140 on the second direction A2 side with respect to the head portion 142.

[0034] The sensor 26 is provided on the first direction A1 side of the side wall of the second cylinder portion 14. The sensor 26 detects, based on a change in the magnetic field, that the head portion 142 has approached the intermediate block 16 as the second piston 141 moves along the arrangement direction. When the sensor 26 detects that the head portion 142 has approached the intermediate block 16, it outputs a detection signal to the control device 11.

[0035] The sensor 27 is provided on the second direction A2 side of the side wall of the second cylinder portion 14. The sensor 27 detects, based on a change in the magnetic field, that the head portion 142 has approached the bottom surface 149 as the second piston 141 moves along the arrangement direction. When the sensor 27 detects that the head portion 142 has approached the bottom surface 149, it outputs a detection signal to the control device 11.

[0036] <Intermediate Block 16> The intermediate block 16 is disposed inside the first cylinder portion 13 and the second cylinder portion 14, at the boundary between the first cylinder portion 13 and the second cylinder portion 14. Specifically, one side (first direction A1 side) of the intermediate block 16 is housed inside the first cylinder portion 13, and the other side (second direction A2 side) is housed inside the second cylinder portion 14. A groove 161 is formed in a region of the inner circumferential wall surface of the first cylinder portion 13 that abuts against the outer circumferential wall surface of the intermediate block 16, and a groove 162 is formed in a region of the inner circumferential wall surface of the second cylinder portion 14 that abuts against the outer circumferential wall surface of the intermediate block 16. Sealing members 163, 164, such as O-rings, are disposed in the grooves 161, 162, respectively.

[0037] As described above, the intermediate block 16 has an insertion hole 160 formed therein. The insertion hole 160 is a through-hole that passes through the intermediate block 16 from the inside to the outside along the arrangement direction with the axis X as its center. As described above, the rod portion 133 of the first piston 131 is inserted into the insertion hole 160. Note that a groove 165 is formed along the inner periphery on the inner circumferential wall surface of the intermediate block 16 that forms the insertion hole 160, and a sealing member 166, such as an O-ring, is disposed in the groove 165.

[0038] <Control device 11> The control device 11 has a processor configured with a semiconductor device such as a CPU, a memory, etc. The control device 11 controls the operation of the pump device 1 by reading and executing a control program that is pre-recorded in a storage medium such as a flash memory, or a control program that is received via a communication interface, etc.

[0039] Specifically, the control device 11 controls the storage of the fluid, i.e., the chemical liquid, in the pump chamber 120 and the discharge of the fluid by controlling the opening and closing of the valves 20, 22, and 23. When discharging the fluid from the pump chamber 120, the control device 11 controls the amount of fluid discharged from the pump chamber 120 (discharge rate) by switching the operation mode of the pump unit 10 between a first operation mode and a second operation mode. The first operation mode is an operation mode in which the fluid is discharged from the pump chamber 120 at a first discharge rate. The second operation mode is an operation mode in which the fluid is discharged from the pump chamber 120 at a second discharge rate that is greater than the first discharge rate. The operation of the pump device 1 in the first operation mode and the second operation mode will be described below.

[0040] <First Operation Mode> In the first operation mode, the control device 11 supplies working air into the first cylinder chamber 130 of the pump unit 10 in the initial state shown in Fig. 2. Specifically, when detection signals are output from the sensors 24 and 26, the control device 11 operates the valve 20 to supply working air into the first cylinder chamber 130 via the first supply / discharge port 135. This working air causes the first piston 131 to start moving in the second direction A2.

[0041] 2 , in the initial state of the pump section 10, the end 133a of the rod portion 133 of the first piston 131 on the second direction A2 side is in contact with the surface 142b of the end of the head portion 142 of the second piston 141 on the first direction A1 side. Therefore, when working air is supplied into the first cylinder chamber 130 and the first piston 131 starts to move in the second direction A2, a force in the second direction A2 is applied to the second piston 141 from the rod portion 133 of the first piston 131. Therefore, the second piston 141 moves in the second direction A2 together with the first piston 131.

[0042] When the first piston 131 and the second piston 141 move in the second direction A2, the head portion 132 of the first piston 131 approaches the intermediate block 16 and the sensor 25. The sensor 25 then detects that the first piston 131 has approached and outputs a detection signal to the control device 11. When the control device 11 receives the detection signal from the sensor 25, it operates the valve 20 to stop the supply of working air to the first cylinder chamber 130.

[0043] Then, the surface 132b on the second direction A2 side of the head portion 132 of the first piston 131 abuts against the surface 167 of the intermediate block 16 in the first direction A1, and the movement of the first piston 131 in the second direction A2 stops. When the movement of the first piston 131 stops, the force from the rod portion 133 in the second direction A2 no longer acts on the second piston 141, and the movement of the second piston 141 also stops.

[0044] 3 is a cross-sectional view of the pump unit 10 when the first piston 131 and the second piston 141 move in the second direction A2 and then stop. As shown in FIG. 3, the second piston 141 moves in the second direction A2 by a length (first protrusion length) D1 by which the rod portion 133 of the first piston 131 protrudes from the surface 168 of the end portion on the second direction A2 side of the intermediate block 16, and then stops. Therefore, the end 143a of the rod portion 143 of the second piston 141 is positioned further in the second direction A2 by the first protrusion length D1 than in the initial state shown in FIG. 2. At this time, the second piston 141 moves a stroke shorter than the full stroke.

[0045] As the second piston 141 moves, the telescopic portion 126 attached to the rod portion 143 also extends by the first protruding length D1. That is, the piston portion 17 extends the telescopic portion 126. As a result, the pressure inside the pump chamber 120 becomes positive according to the amount by which the telescopic portion 126 extends, and the fluid stored in the pump chamber 120 is discharged from the discharge port 122 at a first discharge amount corresponding to the amount by which the telescopic portion 126 extends.

[0046] 3 is reached and the fluid is discharged at the first discharge rate, the control device 11 operates the valve 23 to supply operating air from the third supply / discharge port 147 of the second cylinder portion 14 into the second cylinder chamber 140. This operating air causes the second piston 141 to start moving in the first direction A1. Because the end 133a of the rod portion 133 of the first piston 131 abuts against the surface 142b of the head portion 142 of the second piston 141, both the first piston 131 and the second piston 141 move in the first direction A1.

[0047] When the head portion 132 of the first piston 131 approaches the bottom surface 137 of the first cylinder portion 13 and the head portion 142 of the second piston 141 approaches the surface 168 of the intermediate block 16, the sensors 24 and 26 output detection signals to the control device 11. When the detection signals are output from the sensors 24 and 26, the control device 11 operates the valve 23 to stop the supply of operating air to the second cylinder chamber 140. Then, when the head portion 132 abuts against the bottom surface 137 and the head portion 142 abuts against the surface 168 of the intermediate block 16, the movement of the first piston 131 and the second piston 141 in the first direction A1 stops. As a result, the pump portion 10 returns to the initial state shown in FIG. 2 .

[0048] As the second piston 141 moves in the first direction A1 as described above, the extension / contraction part 126 attached to the rod part 143 contracts by the amount of movement of the second piston 141. In other words, the piston part 17 contracts the extension / contraction part 126. As a result, negative pressure is created inside the pump chamber 120, and fluid is sucked into the pump chamber 120 from the suction port 121.

[0049] When transitioning from the initial state of FIG. 2 to the state of FIG. 3 , the control device 11 may operate the valve 23 to supply working air from the third inlet / outlet port 147 into the second cylinder chamber 140. In this case, the working air is supplied from the third inlet / outlet port 147 into the second cylinder chamber 140 at a pressure lower than the pressure of the working air supplied from the first inlet / outlet port 135, for example, using a regulator. This prevents the second piston 141 from moving alone in the second direction A2 due to inertial force after the first piston 131 abuts against the intermediate block 16 and stops moving. As a result, excessive extension of the extension / retraction section 126 and the discharge of an amount of fluid exceeding the first discharge rate are prevented.

[0050] <Second Operation Mode> In the second operation mode, the control device 11 supplies working air into the second cylinder chamber 140 of the pump section 10 in the initial state shown in FIG. 2 . Specifically, when detection signals are output from the sensors 24 and 26, the control device 11 operates the valve 22 to supply working air into the second cylinder chamber 140 from the second supply / discharge port 146 of the second cylinder section 14. This working air causes the second piston 141 to start moving in the second direction A2. At this time, because working air is not supplied to the first cylinder chamber 130, the first piston 131 does not start moving and remains stopped. That is, the second piston 141 moves away from the first piston 131.

[0051] The second piston 141 moves independently in the second direction A2, and the head portion 142 approaches the bottom surface 149 of the second cylinder portion 14 and the sensor 27. The sensor 27 then detects the approach of the second piston 141 and outputs a detection signal to the control device 11. Upon receiving the detection signal from the sensor 27, the control device 11 operates the valve 22 to stop the supply of working air to the second cylinder chamber 140. The surface 142c of the head portion 142 on the second direction A2 side then abuts against the bottom surface 149, and the movement of the second piston 141 in the second direction A2 stops.

[0052] 4 is a cross-sectional view of the pump unit 10 when the second piston 141 stops after moving in the second direction A2. As shown in FIG. 4, the end 143a of the rod portion 143 is positioned further toward the second direction A2 than in the initial state by a second protruding length D2, which is the length of the rod portion 143 housed in the second cylinder chamber 140 in the initial state. Therefore, the extension / contraction portion 126 attached to the rod portion 143 also extends by the second protruding length D2. In other words, the piston portion 17 extends the extension / contraction portion 126.

[0053] As described above, the volume of the second cylinder chamber 140 is larger than the volume of the first cylinder chamber 130. The second piston 141, which has a longer stroke than the stroke of the first piston 131, operates at its full stroke. Therefore, the second projection length D2 is longer than the first projection length D1. Therefore, the pressure inside the pump chamber 120 becomes positive in accordance with the second projection length D2 to which the extension / contraction section 126 is extended, and the fluid stored in the pump chamber 120 is discharged from the discharge port 122 at a second discharge rate that is larger than the first discharge rate and corresponds to the amount by which the extension / contraction section 126 is extended.

[0054] 4 is reached and the fluid is discharged at the second discharge rate, the control device 11 operates the valve 23 to supply working air from the third supply / discharge port 147 of the second cylinder portion 14 into the second cylinder chamber 140. This working air causes the second piston 141 to start moving in the first direction A1.

[0055] When the surface 142b of the head portion 142 of the second piston 141 approaches the surface 168 of the intermediate block 16, the sensor 26 outputs a detection signal to the control device 11. When the detection signal is output from the sensor 26, the control device 11 operates the valve 23 to stop the supply of working air to the second cylinder chamber 140. Then, when the surface 142b of the head portion 142 abuts against the surface 168 of the intermediate block 16, the movement of the second piston 141 in the first direction A1 stops, and the pump section 10 returns to the initial state shown in FIG.

[0056] As the second piston 141 moves in the first direction A1 as described above, the extension / contraction part 126 attached to the rod part 143 contracts by the amount of movement of the second piston 141. That is, the piston part 17 contracts the extension / contraction part 126. As a result, negative pressure is created inside the pump chamber 120, and fluid is sucked into the pump chamber 120 from the suction port 121.

[0057] <Method for controlling fluid discharge amount> The control device 11 uses the method for controlling fluid discharge amount to control the discharge amount of fluid discharged from the pump unit 10, thereby supplying a desired amount of fluid to the chemical tank 31. At this time, the control device 11 uses the first operation mode and the second operation mode described above to supply a desired amount of fluid to the chemical tank 31.

[0058] First, the control device 11 calculates the number of times to supply the fluid at a first discharge amount in a first operating mode and the number of times to supply the fluid at a second discharge amount in a second operating mode, relative to a desired supply amount (i.e., total discharge amount) L [ml] of fluid to be supplied to the chemical liquid tank 31. In this case, the control device 11 may be connected to, for example, an input interface that accepts user operation input, and may be configured to receive the value of the total discharge amount input by the user from the input interface.

[0059] For example, when the first discharge amount is q [ml] and the second discharge amount is p (>q) [ml], the control device 11 calculates the number of operations n in the first operating mode and the number of operations m in the second operating mode using the following formula (1).

[0060] m=L / p n=(L-m×p) / q (1) However, the control device 11 rounds down the decimal points of the calculation results to make the values ​​of m and n integers.

[0061] Based on the calculation result of the above formula (1), the control device 11 discharges the majority of the total discharge amount at the second discharge amount, and discharges the remaining fine adjustment amount of the total discharge amount at the first discharge amount.

[0062] Instead of inputting the total ejection liquid volume L, the user may input the number of operations n in the first operation mode and the number of operations m in the second operation mode.

[0063] After calculating the number of operations in the first operation mode and the second operation mode, the control device 11 first sets the operation mode to the second operation mode and operates the pump unit 10 in the second operation mode for m operations. In this case, as described above, the control device 11 repeats the control of the supply and discharge of working air to the second cylinder chamber 140 m times.

[0064] When the number of operations in the second operation mode reaches m, the control device 11 switches the operation mode to the first operation mode and operates the pump unit 10 in the first operation mode for n operations. In this case, as described above, the control device 11 repeats the control of supplying working air to the first cylinder chamber 130 and then to the second cylinder chamber 140 n times.

[0065] Fig. 5A is a timing chart showing the operation of the pump unit 10 in the first operation mode and the second operation mode. In Fig. 5A, the horizontal axis represents time t. As shown in Fig. 5A, when the pump unit 10 starts operating in the second operation mode at time t0, fluid is discharged at the second discharge rate in response to the movement of the second piston 141 in the second direction A2, as described above. Then, when the supply of operating air is stopped in response to the output of a detection signal from the sensor 27 at time t1, the discharge of fluid in response to the movement of the second piston 141 stops.

[0066] Thereafter, at time t2 when the stop time has elapsed, the second piston 141 starts moving in the first direction A1, and the fluid is sucked into and stored in the pump chamber 120. Then, at time 3, when the supply of operating air is stopped in response to the output of a detection signal from the sensor 26, the suction of the fluid in response to the movement of the second piston 141 stops. Thereafter, at time t4 when the stop time has elapsed, the discharge of the fluid at the second discharge rate begins. Thereafter, the above operation is repeated m times.

[0067] The stop time is the time required for the check valve 125 to operate to close the discharge flow path 128 after the discharge of the fluid has stopped.

[0068] At time t11, when the stop time has elapsed since time tm, when the discharge and intake of fluid in the second operating mode has been performed m times, the pump unit 10 starts operating in the first operating mode. That is, as described above, the first piston 131 and the second piston 141 both move in the second direction A2, thereby discharging the fluid at the first discharge rate. Then, at time t12, when the supply of operating air is stopped in response to the output of a detection signal from the sensor 25, the discharge of fluid in response to the movement of the first piston 131 and the second piston 141 stops.

[0069] Then, at time t13 when the stop time has elapsed, both the first piston 131 and the second piston 141 begin to move in the first direction A1, and the fluid is sucked into and stored in the pump chamber 120. Then, at time t14, when the supply of operating air is stopped in response to the output of a detection signal from the sensor 24, the suction of fluid in response to the movement of the first piston 131 and the second piston 141 stops. Then, at time t15 when the stop time has elapsed, the discharge of fluid at the first discharge rate begins. Thereafter, the above operation is repeated n times. Note that the stop time is the time required for the check valve 123 to operate to close the suction flow path 124 after the suction of fluid has stopped.

[0070] At time tn, when the stop time has elapsed after n discharges and suctions of fluid in the first operation mode, the discharge of fluid by the pump unit 10 ends. In other words, the total discharge amount of fluid is discharged during the period from time t0 to time tn.

[0071] 6 is a flowchart illustrating the flow of processes performed in the fluid discharge amount control method. Each process shown in the flowchart in FIG. 6 is performed by the control device 11 reading a program recorded on a recording medium such as a flash memory and executing the program.

[0072] In step S1, the control device 11 inputs the value of the total discharge amount of fluid via the input interface. The process then proceeds to step S2. In step S2, the control device 11 uses the above formula (1) to calculate the number of operations in the first operating mode, i.e., the number of operations at the first discharge amount (n), and the number of operations in the second operating mode, i.e., the number of operations at the second discharge amount (m). The process then proceeds to step S3.

[0073] In step S3, the control device 11 operates the pump unit 10 in the second operating mode. Specifically, the control device 11 operates the valve 22 to supply working air into the second cylinder chamber 140 through the second supply / discharge port 146. When the second piston 141 moves in the second direction A2 and the sensor 27 outputs a detection signal, the control device 11 operates the valve 22 to stop the supply of working air to the second cylinder chamber 140. As a result, fluid is discharged from the discharge port 122 at the second discharge rate. Thereafter, the control device 11 operates the valve 23 to supply working air into the second cylinder chamber 140 through the third supply / discharge port 147. When the second piston 141 moves in the first direction A1 and the sensor 26 outputs a detection signal, the control device 11 operates the valve 23 to stop the supply of working air to the second cylinder chamber 140. As a result, fluid is drawn into the pump chamber 120 through the suction port 121.

[0074] In step S4 following step S3, the control device 11 adds 1 to the value of counter i, which counts the number of operations in the second operation mode. Then, the process proceeds to step S5. In step S5, the control device 11 determines whether the number of operations in the second operation mode has reached m, which is the number of operations calculated in step S2. If the number of operations in the second operation mode has reached m, the control device 11 makes a positive determination, and the process proceeds to step S6. If the number of operations in the second operation mode has not reached m, the control device 11 makes a negative determination, and the process returns to step S3.

[0075] In step S6, the control device 11 operates the pump unit 10 in the first operating mode. Specifically, the control device 11 operates the valve 20 to supply working air from the first supply / discharge port 135 into the first cylinder chamber 130. When the first piston 131 and the second piston 141 move in the second direction A2 and a detection signal is output from the sensor 25, the control device 11 operates the valve 20 to stop the supply of working air to the first cylinder chamber 130. As a result, fluid is discharged from the discharge port 122 at the first discharge rate. Thereafter, the control device 11 operates the valve 23 to supply working air from the third supply / discharge port 147 into the second cylinder chamber 140. When the first piston 131 and the second piston 141 move in the first direction A1 and detection signals are output from the sensors 24 and 26, the control device 11 operates the valve 23 to stop the supply of working air to the second cylinder chamber 140. As a result, the fluid is sucked into the pump chamber 120 through the suction port 121 .

[0076] In step S7 following step S6, the control device 11 adds 1 to the value of counter j, which counts the number of operations in the first operation mode. Then, the process proceeds to step S8. In step S8, the control device 11 determines whether the number of operations in the first operation mode has reached n, which is the number of operations calculated in step S2. If the number of operations in the first operation mode has reached n, the control device 11 makes a positive determination, and the process ends. If the number of operations in the first operation mode has not reached n, the control device 11 makes a negative determination, and the process returns to step S6.

[0077] According to the above-described embodiment, at least one of the following advantageous effects can be obtained.

[0078] (1) The pump device 1 includes a pump chamber 120 that accommodates an extension / contraction section 126, a piston section 17 that extends and contracts the extension / contraction section 126 to discharge fluid from the pump chamber 120, and a control device 11 that controls the supply of operating air to the piston section 17 to control the discharge rate of fluid discharged from the pump chamber 120. The control device 11 controls the discharge rate of fluid by switching between a first operating mode in which the fluid is discharged from the pump chamber 120 at a first discharge rate and a second operating mode in which the fluid is discharged from the pump chamber 120 at a second discharge rate that is greater than the first discharge rate. Specifically, in the first operating mode, the control device 11 supplies operating air to the first cylinder chamber 130 to move both the first piston 131 and the second piston 141 along the arrangement direction. In the second operating mode, the control device 11 supplies operating air to the second cylinder chamber 140 to move the second piston 141 alone along the arrangement direction.

[0079] For example, in a pump device capable of discharging a large amount of fluid, if the piston stroke cannot be changed, the number of discharges required to obtain a desired total discharge amount can be reduced, thereby shortening the operating time. However, since the discharge amount cannot be reduced, the amount of fluid discharged from the pump device cannot be finely adjusted, and there is a risk of a large discrepancy between the actual total discharge amount and the desired total discharge amount.

[0080] In addition, in a pump device capable of discharging a small amount of fluid, if the stroke of the piston cannot be changed, the error between the actual total amount of fluid discharged and the desired total amount of fluid discharged can be reduced. However, since the amount discharged in each operation is small, the number of operations increases, and it takes a long time to achieve the total amount of fluid discharged.

[0081] Figure 5(B) is a timing chart of the discharge and suction of fluid until the total discharge volume is reached when using a pump device capable of discharging fluid only at a small discharge volume as described above. In Figure 5(B), as in Figure 5(A), the horizontal axis represents time t. In this case, fluid is discharged from time t0 to time t1, and fluid is suctioned from time t2 to time t3, after the stop time has elapsed. After time t4, after the stop time has elapsed, the same operation is repeated, and the operation ends at time tr, after the stop time has elapsed after the total discharge volume has been reached. As shown in Figure 5(B), the number of discharges and suctions of fluid increases compared to Figure 5(A), so the time tr, at which the operation ends, is later than time tn (see Figure 5(A)).

[0082] Unlike the pump device described above in which the piston stroke cannot be changed, the pump device 1 of this embodiment can alternatively set the fluid discharge rate between a first discharge rate and a second discharge rate that is greater than the first discharge rate. As a result, using a single pump device 1, it is possible to discharge fluid at the second discharge rate, which is a larger discharge rate, thereby shortening the time required to reach the total discharge rate, or to discharge fluid at the first discharge rate, which is a smaller discharge rate, thereby achieving a total discharge rate with little error from the desired discharge rate.

[0083] Furthermore, compared to a case where two pump devices with different discharge rates are used to obtain a total discharge amount of liquid, in this embodiment, fluids can be discharged at different discharge rates using a single pump device 1. This reduces the installation area of ​​the pump device 1, increasing the degree of freedom in installation location. Also, the circuitry of the pump device 1 can be simplified.

[0084] In addition, in the pump device 1 capable of discharging fluid at a large second discharge rate, it is also possible to discharge a small amount of fluid at the first discharge rate in order to adjust the concentration of the chemical liquid (fluid) in the chemical liquid tank 31 over time.

[0085] (2) In the first operating mode, the control device 11 supplies operating air to the first cylinder chamber 130 via the first supply / discharge port 135 to move the first piston 131 and the second piston 141 together along the arrangement direction. In the second operating mode, the control device 11 supplies operating air to the second cylinder chamber 140 via the second supply / discharge port 146 to move the second piston 141 independently along the arrangement direction. This allows a single pump device 1 to discharge fluid at two different discharge rates without using a complex structure.

[0086] (3) The control device 11 calculates the number of times the fluid is discharged at the first discharge rate and the number of times the fluid is discharged at the second discharge rate with respect to the total discharge rate of the fluid discharged from the pump chamber 120. This makes it possible to obtain a total discharge rate with a small error relative to the desired total discharge rate in a short time.

[0087] The present invention is not limited to the details described in the above embodiments, and other embodiments that are conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention.

[0088] In the embodiment, the pump device 1 includes the first piston 131 and the second piston 141, which have different strokes, but is not limited to this example and may include three or more pistons. In this case, for example, a piston (referred to as a third piston) having a longer stroke than the first piston 131 and a shorter stroke than the second piston 141 may be arranged between the first piston 131 and the second piston 141.

[0089] In the first operating mode, the first piston 131, the third piston, and the second piston 141 move together, thereby discharging the fluid at the first discharge rate, as in the embodiment. In the second operating mode, only the second piston 141 moves, thereby discharging the fluid at the second discharge rate. Furthermore, by supplying operating air to the piston chamber accommodating the third piston, the third piston and the second piston 141 may move together, thereby discharging the fluid at a discharge rate greater than the first discharge rate and less than the second discharge rate. This increases the discharge rate available for fine adjustment of the total discharge rate, making it possible to obtain a total discharge rate with a smaller error compared to the desired total discharge rate.

[0090] REFERENCE SIGNS LIST 1 Pump device, 10 Pump section, 11 Control device, 12 Housing, 13 First cylinder section, 14 Second cylinder section, 17 Piston section, 120 Pump chamber, 126 Extension section, 130 First cylinder chamber, 131 First piston, 135 First supply / discharge port, 140 Second cylinder chamber, 141 Second piston, 146 Second supply / discharge port, 147 Third supply / discharge port

Claims

1. A pump chamber that accommodates an extension / contraction section, a piston section that extends and contracts the extension / contraction section to discharge a fluid in the pump chamber, and a control device that controls the supply of operating air to the piston section to control the amount of fluid discharged from the pump chamber, wherein the piston section has: a first cylinder chamber; a second cylinder chamber that is arranged between the first cylinder chamber and the pump chamber and has a volume larger than that of the first cylinder chamber; a first piston that is accommodated in the first cylinder chamber so as to be reciprocating along an arrangement direction in which the first cylinder chamber and the second cylinder chamber are arranged; and a second piston that is accommodated in the second cylinder chamber so as to be reciprocating along the arrangement direction together with the first piston or alone, wherein the stroke of the second piston is longer than the stroke of the first piston, and one end of the second piston is connected to the extension / contraction section, and the other end is capable of abutting and separating from the first piston, The control device controls the amount of fluid discharged from the pump chamber by switching between an operating mode of a first operating mode in which operating air is supplied to the first cylinder chamber, the first piston and the second piston are moved together along the arrangement direction, and fluid is discharged from the pump chamber at a first discharge rate, and a second operating mode in which operating air is supplied to the second cylinder chamber, the second piston is moved independently along the arrangement direction, and fluid is discharged from the pump chamber at a second discharge rate that is greater than the first discharge rate.

2. A pump device as described in claim 1, wherein the first cylinder chamber is provided with a first supply and discharge port through which working air is supplied and discharged, and the second cylinder chamber is provided with a second supply and discharge port through which working air is supplied and discharged, and the control device, in the first operating mode, supplies working air to the first cylinder chamber via the first supply and discharge port to move the first piston and the second piston together along the arrangement direction, and in the second operating mode, supplies working air to the second cylinder chamber via the second supply and discharge port to move the second piston independently along the arrangement direction.

3. A pump device as described in claim 2, wherein the second cylinder chamber is further provided with a third supply / discharge port through which operating air is supplied / discharged, and the control device, when in the first operating mode, supplies operating air of a lower pressure than the operating air supplied to the first cylinder chamber to the second cylinder chamber via the third supply / discharge port.

4. A pump device according to any one of claims 1 to 3, wherein the volume of the second cylinder chamber is at least twice the volume of the first cylinder chamber.

5. A fluid discharge amount control method for controlling the amount of fluid discharged from a pump chamber using a pump device including a pump chamber accommodating an extension / contraction section, a first cylinder chamber accommodating a first piston, and a second cylinder chamber accommodating a second piston arranged between the pump chamber and the first cylinder chamber, having a longer stroke than the first piston and connected to the extension / contraction section, the method comprising: switching between an operation mode between a first operation mode in which operating air is supplied to the first cylinder chamber, the first piston and the second piston are moved together along an arrangement direction in which the first cylinder chamber and the second cylinder chamber are arranged, and the extension / contraction section is expanded and contracted to discharge fluid from the pump chamber at a first discharge amount; and a second operation mode in which operating air is supplied to the second cylinder chamber, the second piston is moved independently along the arrangement direction, and the extension / contraction section is expanded and contracted to discharge fluid from the pump chamber at a second discharge amount greater than the first discharge amount, to control the amount of fluid discharged.

6. A method for controlling a fluid discharge amount as described in claim 5, wherein, in the first operating mode, operating air is supplied to the first cylinder chamber via a first supply / discharge port provided in the first cylinder chamber, causing the first piston and the second piston to move together along the arrangement direction, and, in the second operating mode, operating air is supplied to the second cylinder chamber via a second supply / discharge port provided in the second cylinder chamber, causing the second piston to move independently along the arrangement direction.

7. A fluid discharge amount control method as claimed in claim 6, further comprising the step of calculating the number of times the fluid is discharged at a first discharge amount and the number of times the fluid is discharged at a second discharge amount with respect to a total discharge amount of liquid discharged from the pump chamber.

Images