Bellows Pump Device

Abstract

To suppress impact pressure occurring when switching from suction to discharge of transfer fluid, in a bellows pump device that reduces pulsation on a discharge side.SOLUTION: A bellows pump device 1 comprises a control unit 6 that controls the operation of a first drive unit 27 and a second drive unit 28 so that based on respective detection signals of a first detection unit 29 and a second detection unit 31, extension drive of a first bellows 13 (second bellows 14) is stopped at a first intermediate extension state (second extension intermediate state) before a maximum extension state, and then, before the second bellows 14 (first bellows 13) reaches a maximum contraction state, contraction drive of the first bellows 13 (second bellows 14) is started.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a bellows pump device. [Background technology]

[0002] Bellows pumps used to deliver transfer fluids such as chemicals and solvents in semiconductor manufacturing, chemical industries, etc., include a pair of bellows that expand and contract independently to draw in and discharge the transfer fluid, and a pair of air cylinders that expand and contract each bellows by supplying and discharging pressurized air (see, for example, Patent Document 1). The bellows pump described in Patent Document 1 controls the drive of each air cylinder so that just before one bellows is fully contracted (ends discharge), the other bellows contracts from its fully extended state to discharge the transfer fluid.

[0003] By controlling the drive of each air cylinder as described above, when one bellows switches from contraction to expansion (from discharging to suctioning the transferred fluid), the other bellows is already contracted and discharging the transferred fluid. This reduces a large drop in the discharge pressure of the transferred fluid at this timing, thereby reducing pulsation on the discharge side of the bellows pump. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-293502 Summary of the Invention [Problem to be solved by the invention]

[0005] In the bellows pump, the pressure of the pressurized air supplied to each air cylinder is increased to increase the discharge flow rate of the transported fluid. However, increasing the air pressure causes a momentary large pressure fluctuation (pressure increase) within the bellows when the bellows switches from expansion to contraction (especially when the bellows stops expanding), generating a shock pressure known as "water hammer." The occurrence of such a shock pressure can have adverse effects on semiconductor manufacturing processes, etc.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to suppress the impact pressure that occurs when switching from suction to discharge of transported fluid in a bellows pump device that reduces pulsation on the discharge side. [Means for solving the problem]

[0007] (1) The bellows pump device of the present disclosure includes a first bellows and a second bellows that are independently expandable between a fully expanded state and a fully contracted state, sucking a transfer fluid into the inside when expanded and discharging the transfer fluid from the inside when contracted, a first drive unit that actively drives the first bellows to expand and contract, a second drive unit that actively drives the second bellows to expand and contract, a first detector that detects the expansion and contraction state of the first bellows, a second detector that detects the expansion and contraction state of the second bellows, and a controller that controls the first detector and the second detector. and a control unit that controls the operation of the first drive unit and the second drive unit so that, based on each detection signal from the detection unit, the extension drive of the first bellows is stopped at a first intermediate extension state before the maximum extension state, and then the contraction drive of the first bellows is started just before the second bellows reaches the maximum contraction state, and the extension drive of the second bellows is stopped at a second intermediate extension state before the maximum extension state, and then the contraction drive of the second bellows is started just before the first bellows reaches the maximum contraction state.

[0008] According to the above bellows pump device, the control unit starts contracting the first bellows (second bellows) just before the second bellows (first bellows) reaches its most contracted state. This allows the first bellows (second bellows) to already be discharging the transferred fluid when the second bellows (first bellows) switches from discharging to suction, thereby reducing a drop in the discharge pressure of the transferred fluid at the switching timing. As a result, pulsation on the discharge side of the bellows pump device can be reduced.

[0009] Furthermore, the control unit stops the active extension drive of the first bellows (second bellows) at a first mid-extension state (second mid-extension state) that is just before the fully extended state. Therefore, even if a pressure increase occurs in the first bellows (second bellows) due to impact pressure when the extension drive of the first bellows (second bellows) is stopped, the first bellows (second bellows) passively expands from the first mid-extension state (second mid-extension state), thereby absorbing the pressure increase. This makes it possible to suppress the impact pressure that occurs when switching from suction to discharge of the transport fluid.

[0010] (2) It is preferable that the first mid-extension state is a state in which an extension allowance is secured for passive extension of the first bellows due to an increase in pressure within the first bellows, and that the second mid-extension state is a state in which an extension allowance is secured for passive extension of the second bellows due to an increase in pressure within the second bellows. In this case, in the first mid-extension state (second mid-extension state), an extension margin is ensured that allows the first bellows (second bellows) to passively extend, and this passive extension can effectively absorb the pressure increase within the first bellows (second bellows), thereby further suppressing the impact pressure.

[0011] (3) It is preferable that the control unit controls the operation so that the time difference between stopping the extension drive of the first bellows in the first mid-extension state and starting the contraction drive of the first bellows is equal to or greater than the first time defined below, and the time difference between stopping the extension drive of the second bellows in the second mid-extension state and starting the contraction drive of the second bellows is equal to or greater than the second time defined below. First time: The time it takes for the first bellows to passively expand due to a pressure increase in the first bellows. Second time: The time it takes for the second bellows to passively expand due to the pressure increase in the second bellows.

[0012] If the first bellows (second bellows) is passively expanded when the contraction drive of the first bellows (second bellows) begins just before the second bellows (first bellows) reaches its maximum contraction state to discharge the transfer fluid, the transfer fluid in the first bellows (second bellows) cannot be discharged immediately, and the discharge pressure of the transfer fluid cannot be increased immediately, which may result in the inability to effectively reduce pulsation on the discharge side of the bellows pump device.

[0013] In contrast, according to the above-described configuration (3), the time difference between stopping the active expansion drive of the first bellows (second bellows) in the first mid-expansion state (second mid-expansion state) and starting the contraction drive of the first bellows (second bellows) is controlled to be equal to or longer than the first time (second time), which is the passive expansion time of the first bellows (second bellows). Therefore, the passive expansion of the first bellows (second bellows) can be reliably completed within the first time (second time). This allows the contraction drive of the first bellows (second bellows) to be started immediately at the above-described time point, thereby effectively reducing the pulsation on the discharge side of the bellows pump device while suppressing the impact pressure. [Effects of the Invention]

[0014] According to the present disclosure, in a bellows pump device that reduces pulsation on the discharge side, it is possible to suppress the impact pressure that occurs when switching from suction to discharge of transported fluid. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic configuration diagram of a bellows pump device according to an embodiment of the present disclosure. FIG. [Figure 2] FIG. 1 is a cross-sectional view of a bellows pump. [Figure 3] FIG. 4 is an explanatory diagram showing the operation of a bellows pump. [Figure 4] FIG. 4 is an explanatory diagram showing the operation of a bellows pump. [Figure 5] 4 is a time chart showing an example of operation control performed by a control unit. DETAILED DESCRIPTION OF THE INVENTION

[0016] Next, embodiments of the present disclosure will be described with reference to the accompanying drawings. [Overall configuration] 1 is a schematic diagram of a bellows pump device according to an embodiment of the present disclosure. The bellows pump device 1 of this embodiment is used to supply a constant amount of transfer fluid such as a chemical solution or a solvent in, for example, a semiconductor manufacturing device. The bellows pump device 1 includes an air supply device (fluid supply device) 2, a mechanical regulator 3, a first solenoid valve 4, a second solenoid valve 5, a control unit 6, a bellows pump 10, a first electropneumatic regulator (first fluid pressure adjustment unit) 51, and a second electropneumatic regulator (second fluid pressure adjustment unit) 52.

[0017] The air supply device 2 is made up of, for example, an air compressor, and generates pressurized air (pressurized fluid) to be supplied to the bellows pump 10. The mechanical regulator 3 manually adjusts the air pressure (fluid pressure) of the pressurized air generated by the air supply device 2. The first electropneumatic regulator 51 and the second electropneumatic regulator 52 will be described later.

[0018] 2 is a cross-sectional view of a bellows pump 10. The bellows pump 10 of this embodiment includes a pump head 11 located in the center, a pair of pump cases 12 attached to both left and right sides of the pump head 11, a pair of bellows, a first bellows 13 and a second bellows 14, attached to the left and right sides of the pump head 11 inside each pump case 12, and a total of four check valves 15 and 16 attached to the left and right sides of the pump head 11 inside each of the first and second bellows 13 and 14.

[0019] [Bellows] The first bellows 13 and the second bellows 14 are formed in a cylindrical shape with a bottom and made of a fluororesin such as polytetrafluoroethylene (PTFE) or tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA). Flanges 13a and 14a are integrally formed at the open ends of the first and second bellows 13, 14, and are fixed by being pressed against the side of the pump head 11 in an airtight manner.

[0020] The peripheral wall 13b of the first bellows 13 and the peripheral wall 14b of the second bellows 14 are each formed in a bellows shape and are configured to be able to expand and contract in the left-right direction independently of each other. A thick-walled portion 13c that is thicker than the peripheral wall 13b is integrally formed at the closed side end of the first bellows 13. Similarly, a thick-walled portion 14c that is thicker than the peripheral wall 14b is integrally formed at the closed side end of the second bellows 14. The thicknesses of the thick-walled portions 13c and 14c are set so that they do not elastically deform even when a pressure increase occurs inside the first and second bellows 13 and 14 due to impact pressure.

[0021] An actuating plate 19 is fixed in close contact with the outer surfaces of the thick-walled portions 13c, 14c of the first and second bellows 13, 14 by means of bolts 17 and nuts 18. As a result, the first and second bellows 13, 14 can freely expand and contract between a maximum extended state in which the outer surface of the actuating plate 19 abuts against the inner surface of the bottom wall portion 121 of the cylindrical pump case 12 with a bottom, and a maximum contracted state in which the inner surface of a piston body 23 (described later) abuts against the outer surface of the bottom wall portion 121.

[0022] [Pump case] The opening periphery of pump case 12 (hereinafter also referred to as "first pump case 12A") is airtightly pressed and fixed to flange portion 13a of first bellows 13. As a result, a first discharge-side air chamber (first discharge-side fluid chamber) 21A that is kept airtight is formed outside first bellows 13 inside first pump case 12A.

[0023] A first intake / exhaust port 22A is provided in the first pump case 12A, and the first intake / exhaust port 22A is connected to the air supply device 2 via the first solenoid valve 4, the first electropneumatic regulator 51, and the mechanical regulator 3 (see FIG. 1). As a result, when pressurized air is supplied from the air supply device 2 to the inside of the first discharge-side air chamber 21A, the first bellows 13 contracts.

[0024] The peripheral edge of the opening of pump case 12 (hereinafter also referred to as "second pump case 12B") is airtightly pressed and fixed to flange portion 14a of second bellows 14. As a result, a second discharge-side air chamber (second discharge-side fluid chamber) 21B that is kept airtight is formed outside second bellows 14 inside second pump case 12B.

[0025] A second intake / exhaust port 22B is provided in the second pump case 12B, and the second intake / exhaust port 22B is connected to the air supply device 2 via the second solenoid valve 5, the second electropneumatic regulator 52, and the mechanical regulator 3 (see FIG. 1). As a result, when pressurized air is supplied from the air supply device 2 to the inside of the second discharge-side air chamber 21B, the second bellows 14 contracts.

[0026] A rod-shaped connecting member 20 penetrates the bottom wall 121 of each pump case 12A, 12B, and is supported so as to be slidable in the left-right direction relative to the bottom wall 121. A piston body 23 is fixed to the outer end of the connecting member 20 by a nut 24. The piston body 23 is supported so as to be slidable in the left-right direction relative to the inner circumferential surface of a cylindrical cylinder body 25 that is integrally provided on the outside of the bottom wall 121 while maintaining an airtight state.

[0027] As a result, on the first pump case 12A side, the space surrounded by bottom wall 121, cylinder body 25, and piston body 23 is defined as first suction-side air chamber (first suction-side fluid chamber) 26A, which is kept airtight. On the second pump case 12B side, the space surrounded by bottom wall 121, cylinder body 25, and piston body 23 is defined as second suction-side air chamber (second suction-side fluid chamber) 26B, which is kept airtight.

[0028] An intake / exhaust port 251 communicating with the first suction-side air chamber 26A is formed in the cylinder body 25 on the first pump case 12A side. This intake / exhaust port 251 is connected to the air supply device 2 via the first solenoid valve 4, the first electropneumatic regulator 51, and the mechanical regulator 3 (see FIG. 1). As a result, when pressurized air is supplied from the air supply device 2 to the inside of the first suction-side air chamber 26A via the intake / exhaust port 251, the first bellows 13 expands.

[0029] An intake / exhaust port 252 communicating with the second suction-side air chamber 26B is formed in the cylinder body 25 on the second pump case 12B side. This intake / exhaust port 252 is connected to the air supply device 2 via the second solenoid valve 5, the second electropneumatic regulator 52, and the mechanical regulator 3 (see FIG. 1). As a result, when pressurized air is supplied from the air supply device 2 to the inside of the second suction-side air chamber 26B via the intake / exhaust port 252, the second bellows 14 expands.

[0030] With the above configuration, the first pump case 12A, in which the first discharge side air chamber 21A is formed, and the piston body 23 and cylinder body 25, which form the first suction side air chamber 26A, form the first drive unit 27, which actively drives the first bellows 13 to expand and contract. In addition, a second drive unit 28 that actively drives the second bellows 14 to expand and contract is formed by a second pump case 12B in which a second discharge side air chamber 21B is formed, and a piston body 23 and a cylinder body 25 that form a second suction side air chamber 26B.

[0031] [Detection unit] A pair of proximity sensors 29A and 29B are attached to the cylinder body 25 of the first drive unit 27. A detection target plate 30 that is detected by each of the proximity sensors 29A and 29B is attached to the piston body 23 of the first drive unit 27. The detection target plate 30 reciprocates together with the piston body 23, thereby alternately approaching the proximity sensors 29A and 29B.

[0032] Proximity sensor 29A is disposed in a position where it detects detectable plate 30 when first bellows 13 is in a first intermediate contraction state (described later) just before it reaches its fully contracted state. Proximity sensor 29B is disposed in a position where it detects detectable plate 30 when first bellows 13 is in a first intermediate extension state (described later) just before it reaches its fully extended state. When each of proximity sensors 29A, 29B detects detectable plate 30, it outputs a detection signal to control unit 6. The pair of proximity sensors 29A, 29B function as a first detection unit that detects the expansion / contraction state of first bellows 13.

[0033] A pair of proximity sensors 31A and 31B are attached to the cylinder body 25 of the second drive unit 28. A detectable plate 32 that is detected by each of the proximity sensors 31A and 31B is attached to the piston body 23 of the second drive unit 28. The detectable plate 32 reciprocates together with the piston body 23, thereby alternately approaching the proximity sensors 31A and 31B.

[0034] Proximity sensor 31A is disposed in a position where it detects detectable plate 30 when second bellows 14 is in a second mid-contraction state (described later) just before reaching the fully contracted state. Proximity sensor 31B is disposed in a position where it detects detectable plate 32 when second bellows 14 is in a second mid-extension state (described later) just before reaching the fully extended state. When each of proximity sensors 31A, 31B detects detectable plate 30, it outputs a detection signal to control unit 6. The pair of proximity sensors 31A, 31B function as a second detection unit that detects the expansion / contraction state of second bellows 14.

[0035] [Pump head] The pump head 11 is made of a fluororesin such as PTFE or PFA. A suction passage 34 and a discharge passage 35 for the transported fluid are formed inside the pump head 11. The suction passage 34 and the discharge passage 35 open on the outer circumferential surface of the pump head 11 and are connected to a suction port and a discharge port (both not shown) provided on the outer circumferential surface.

[0036] The suction port is connected to a storage tank or the like for the transferred fluid, and the discharge port is connected to the destination of the transferred fluid. In addition, the suction passage 34 and the discharge passage 35 branch out toward the left and right sides of the pump head 11, respectively, and have suction ports 36 and discharge ports 37 that open on the left and right sides of the pump head 11. Each suction port 36 and each discharge port 37 communicates with the interior of the bellows 13, 14 via check valves 15, 16, respectively.

[0037] [Check valve] Each suction port 36 and each discharge port 37 is provided with a check valve 15, 16. The check valve 15 (hereinafter also referred to as the "suction check valve") attached to the suction port 36 has a valve case 15a, a valve body 15b housed in this valve case 15a, and a compression coil spring 15c that urges this valve body 15b in the valve closing direction.

[0038] Valve case 15a is formed in a cylindrical shape with a bottom. A through-hole 15d is formed in the bottom wall of valve case 15a, which communicates with the interior of bellows 13, 14. Valve element 15b closes suction port 36 (closes the valve) due to the biasing force of compression coil spring 15c, and opens suction port 36 (opens the valve) when back pressure is applied by the flow of transport fluid accompanying the expansion and contraction of bellows 13, 14.

[0039] As a result, the suction check valve 15 opens when the bellows 13, 14 in which it is placed expands, allowing the transfer fluid to be sucked in one direction from the suction passage 34 toward the inside of the bellows 13, 14. In addition, the suction check valve 15 closes when the bellows 13, 14 in which it is placed contracts, preventing the transfer fluid from flowing back in the other direction from the inside of the bellows 13, 14 toward the suction passage 34.

[0040] The check valve 16 (hereinafter also referred to as the "discharge check valve") attached to the discharge port 37 has a valve case 16a, a valve body 16b housed in this valve case 16a, and a compression coil spring 16c that biases this valve body 16b in the valve closing direction.

[0041] The valve case 16a is formed in a cylindrical shape with a bottom. A through-hole 16d that communicates with the interior of the bellows 13, 14 is formed in the bottom wall of the valve case 16a. The valve element 16b closes (closes) the through-hole 16d of the valve case 16a by the biasing force of the compression coil spring 16c, and opens (opens) the through-hole 16d of the valve case 16a when back pressure is applied by the flow of the transport fluid that accompanies the expansion and contraction of the bellows 13, 14.

[0042] As a result, discharge check valve 16 opens when bellows 13, 14 in which it is placed contracts, allowing the transferred fluid to flow out in one direction (from inside bellows 13, 14 toward discharge passage 35). On the other hand, discharge check valve 16 closes when bellows 13, 14 in which it is placed expands, preventing the transferred fluid from flowing back in the other direction (from discharge passage 35 toward inside bellows 13, 14).

[0043] [Bellows pump operation] Next, the operation of the bellows pump 10 of this embodiment will be described with reference to Figures 3 and 4. Note that Figures 3 and 4 show simplified configurations of the first and second bellows 13, 14. As shown in Figure 3, when the first bellows 13 contracts and the second bellows 14 expands, valve elements 15b, 16b of suction check valve 15 and discharge check valve 16, which are attached to the left side of pump head 11 in the figure, receive pressure from the transferred fluid in first bellows 13 and move to the right side of valve cases 15a, 16a in the figure. This closes suction check valve 15 and opens discharge check valve 16, causing the transferred fluid in first bellows 13 to be discharged from discharge passage 35 to the outside of the pump.

[0044] Meanwhile, valve element 15b of suction check valve 15, which is mounted on the right side of pump head 11 in the figure, moves to the right side of valve case 15a in the figure due to the suction action of second bellows 14. Valve element 16b of discharge check valve 16, which is mounted on the right side of pump head 11 in the figure, moves to the right side of valve case 16a in the figure due to the suction action of second bellows 14 and the pressing action of the transfer fluid discharged from first bellows 13 to discharge passage 35. As a result, suction check valve 15 opens and discharge check valve 16 closes, and the transfer fluid is sucked into second bellows 14 from suction passage 34.

[0045] 4, when first bellows 13 expands and second bellows 14 contracts, valve elements 15b, 16b of suction check valve 15 and discharge check valve 16, which are mounted on the right side of pump head 11 in the figure, receive pressure from the transferred fluid in second bellows 14 and move to the left side of valve cases 15a, 16a in the figure. As a result, suction check valve 15 closes and discharge check valve 16 opens, and the transferred fluid in second bellows 14 is discharged from discharge passage 35 to the outside of the pump.

[0046] Meanwhile, valve element 15b of suction check valve 15, which is attached to the left side of pump head 11 in the figure, moves to the left side of valve case 15a in the figure due to the suction action of first bellows 13. Valve element 16b of discharge check valve 16, which is attached to the left side of pump head 11 in the figure, moves to the left side of valve case 16a in the figure due to the suction action of first bellows 13 and the pressing action of the transfer fluid discharged from first bellows 13 to discharge passage 35. As a result, suction check valve 15 opens and discharge check valve 16 closes, and the transfer fluid is sucked into first bellows 13 from suction passage 34. By repeating the above operation, the left and right bellows 13, 14 can alternately suck in and discharge the transported fluid.

[0047] [Solenoid valve] 1, the first solenoid valve 4 is, for example, a three-position solenoid switching valve having a pair of solenoids 4a and 4b. Each solenoid 4a, 4b is excited based on a command signal received from the control unit 6. As a result, the first solenoid valve 4 is switched by the control unit 6. The first solenoid valve 4 switches, in the first drive unit 27, between supplying and discharging pressurized air to and from the first discharge air chamber 21A and the first suction air chamber 26A.

[0048] Specifically, when the solenoid 4a is excited, the first solenoid valve 4 switches to a state where it supplies pressurized air to the first discharge air chamber 21A and discharges the pressurized air from the first suction air chamber 26A. When the solenoid 4b is excited, the first solenoid valve 4 switches to a state where it discharges the pressurized air from the first discharge air chamber 21A and supplies pressurized air to the first suction air chamber 26A.

[0049] The second solenoid valve 5 is, for example, a three-position solenoid switching valve having a pair of solenoids 5a and 5b. Each solenoid 5a, 5b is excited in response to a command signal from the control unit 6. This allows the second solenoid valve 5 to be switched by the control unit 6. The second solenoid valve 5 switches between supplying and discharging pressurized air to and from the second discharge-side air chamber 21B and the second suction-side air chamber 26B in the second drive unit 28.

[0050] Specifically, when solenoid 5a is excited, second solenoid valve 5 switches to a state where it supplies pressurized air to second discharge air chamber 21B and discharges pressurized air from second suction air chamber 26B. When solenoid 5b is excited, second solenoid valve 5 switches to a state where it discharges pressurized air from second discharge air chamber 21B and supplies pressurized air to second suction air chamber 26B. Although the first and second solenoid valves 4 and 5 in this embodiment are three-position solenoid switching valves, they may be two-position solenoid switching valves that do not have a neutral position.

[0051] [Electro-pneumatic regulator] The first electropneumatic regulator 51 is disposed between the mechanical regulator 3 and the first solenoid valve 4. The first electropneumatic regulator 51 adjusts the air pressure (first fluid pressure) of the pressurized air supplied to the first suction-side air chamber 26A of the first drive unit 27, and the air pressure of the pressurized air supplied to the first discharge-side air chamber 21A of the first drive unit 27.

[0052] The second electropneumatic regulator 52 is disposed between the mechanical regulator 3 and the second solenoid valve 5. The second electropneumatic regulator 52 adjusts the air pressure (second fluid pressure) of the pressurized air supplied to the second suction-side air chamber 26B of the second drive unit 28, and the air pressure of the pressurized air supplied to the second discharge-side air chamber 21B of the second drive unit 28.

[0053] In this embodiment, electropneumatic regulators 51, 52 that directly adjust the air pressure are used as the first and second fluid pressure adjustment units, but the air pressure may be adjusted indirectly using an air flow adjustment valve that adjusts the air flow rate, or equipment that adjusts the pressure or flow rate of a gas other than air (e.g., nitrogen) or liquid may be used.

[0054] [Control Unit] 1 and 2, the control unit 6 is configured to include a computer having a CPU and the like. Each function of the control unit 6 is realized by the CPU executing a control program stored in a storage device of the computer. The control unit 6 controls the operation of the first drive unit 27 and the second drive unit 28 by switching the first solenoid valve 4 and the second solenoid valve 5 based on the detection signals of the first detection unit 29 and the second detection unit 31.

[0055] In the above-mentioned operation control, the control unit 6 controls the operation of the first drive unit 27 and the second drive unit 28 based on the detection signals of the first detection unit 29 and the second detection unit 31 so as to stop the extension drive of the first bellows 13 at a first intermediate extension state just before the maximum extension state, and then start the contraction drive of the first bellows 13 when the second bellows 14 reaches a second intermediate contraction state just before the maximum contraction state.

[0056] The "first intermediate extension state" of the first bellows 13 means that the extension progress position of the first bellows 13 is closer to the fully extended state than the fully contracted state, and that the extension margin is secured so that the first bellows 13 can passively extend due to an increase in pressure inside the first bellows 13. More specifically, the "first intermediate extension state" means that the extension progress position of the first bellows 13 is at a position extended within a range of 50% to 95% of the extension length from the fully contracted state to the fully extended state.

[0057] The "second mid-contraction state" of the second bellows 14 means that the position of the second bellows 14 in the progress of contraction is closer to the fully contracted state than to the fully extended state. More specifically, the "second mid-contraction state" means that the position of the second bellows 14 in the progress of contraction is in a range of more than 50% and not more than 95% of the contraction length from the fully extended state to the fully contracted state.

[0058] In addition, in the above-mentioned operation control, the control unit 6 controls the operations of the first drive unit 27 and the second drive unit 28 based on the detection signals of the first detection unit 29 and the second detection unit 31 so as to stop the extension drive of the second bellows 14 at a second intermediate extension state just before the maximum extension state, and then start the contraction drive of the second bellows 14 when the first bellows 13 reaches a first intermediate contraction state just before the maximum contraction state.

[0059] The "second intermediate extension state" of the second bellows 14 means that the extension progress position of the second bellows 14 is closer to the fully extended state than the fully contracted state, and that the extension margin is secured so that the second bellows 14 can passively extend due to an increase in pressure within the second bellows 14. More specifically, the "second intermediate extension state" means that the extension progress position of the second bellows 14 is at a position extended within a range of 50% to 95% of the extension length from the fully contracted state to the fully extended state.

[0060] The "first mid-contraction state" of the first bellows 13 means that the contraction progress position of the first bellows 13 is closer to the fully contracted state than to the fully extended state. More specifically, the "first mid-contraction state" means that the contraction progress position of the first bellows 13 is at a position that is contracted within a range of more than 50% and not more than 95% of the contraction length from the fully extended state to the fully contracted state.

[0061] The control unit 6 controls the operation so that the time difference between stopping the expansion drive of the first bellows 13 in the first expansion midway state and starting the contraction drive of the first bellows 13 is equal to or greater than the first time T10. The "first time" is the time it takes for the first bellows 13 to passively expand due to a pressure increase inside the first bellows 13 (the time from the start of expansion to the end of expansion). The control unit 6 of this embodiment controls the operation so that the time difference for the first bellows 13 is equal to the first time T10.

[0062] Note that the first time T10 may be set to a time other than the above. For example, the first time T10 may be set to the time it takes for the first bellows 13 to passively expand from the first intermediate expansion state to the fully expanded state due to a pressure increase within the first bellows 13.

[0063] The control unit 6 controls the operation so that the time difference between when the expansion drive of the second bellows 14 is stopped in the second expansion midway state and when the contraction drive of the second bellows 14 is started is equal to or greater than the second time T20. The "second time" refers to the time it takes for the second bellows 14 to passively expand due to a pressure increase within the second bellows 14 (the time from the start of expansion to the end of expansion). The control unit 6 of this embodiment controls the operation so that the time difference for the second bellows 14 is equal to the second time T20.

[0064] The second time T20 may be set to a time other than the above. For example, the second time T20 may be set to the time it takes for the second bellows 14 to passively expand from the second intermediate expansion state to the fully expanded state due to a pressure increase within the second bellows 14.

[0065] [Motion Control] Fig. 5 is a time chart showing an example of the operational control performed by the control unit 6. The operational control performed by the control unit 6 will be described below with reference to Fig. 1 and Fig. 5. Here, the description will start from time t0 when the first bellows 13 is in the most contracted state and the second bellows 14 is in the contracting operation (discharging).

[0066] At time t0, the control unit 6 de-energizes the solenoid 4a of the first solenoid valve 4 and energizes the solenoid 4b. Note that at time t0, the solenoid 5a of the second solenoid valve 5 is energized and the solenoid 5b is de-energized. When the solenoid 4b of the first solenoid valve 4 is energized, pressurized air generated by the air supply device 2 is supplied to the first suction-side air chamber 26A of the first drive unit 27 via the mechanical regulator 3, the first electropneumatic regulator 51, and the first solenoid valve 4. As a result, the first drive unit 27 begins actively driving the first bellows 13, which is in the most contracted state, to extend.

[0067] At this time, the control unit 6 controls the expansion speed of the first bellows 13 by the first drive unit 27 so that the time difference (t2-t1) from time t1 to time t2, which will be described later, becomes a first time T10 (for example, 30 msec to 60 msec), thereby advancing or delaying time t1. Specifically, while the first bellows 13 is actively driven to expand from time t0 to time t1, the control unit 6 outputs a control command to the first electropneumatic regulator 51, causing the first electropneumatic regulator 51 to adjust the air pressure of the pressurized air supplied to the first suction-side air chamber 26A. In this way, the expansion speed of the first bellows 13 by the first drive unit 27 is controlled.

[0068] Next, at time t1 when proximity sensor 29B detects (ON) that first bellows 13 is in the first mid-extension state, control unit 6 demagnetizes solenoid 4b of first solenoid valve 4. As a result, first drive unit 27 stops the active extension drive of first bellows 13 in the first mid-extension state. When the active extension drive of first bellows 13 stops, the transfer fluid is no longer sucked in within first bellows 13, changing the flow of the transfer fluid, generating an impact pressure. This impact pressure causes a pressure increase within first bellows 13.

[0069] Due to the pressure increase inside the first bellows 13, the first bellows 13 passively expands from the first intermediate expansion state within the first time T10. Here, the first bellows 13 passively expands to the fully expanded state. By passively expanding the first bellows 13 in this manner, the pressure increase inside the first bellows 13 can be absorbed before the first time T10 has elapsed.

[0070] Next, at time t2 when proximity sensor 31A detects (ON) that second bellows 14 is in the second mid-deflation state, control unit 6 energizes solenoid 4a of first solenoid valve 4. Pressurized air generated by air supply device 2 is then supplied to first discharge-side air chamber 21A of first drive unit 27 via mechanical regulator 3, first electropneumatic regulator 51, and first solenoid valve 4. As a result, first drive unit 27 begins actively driving first bellows 13, which is in the fully extended state, to contract just before second bellows 14 reaches the fully contracted state. As a result, both first bellows 13 and second bellows 14 are driven to contract.

[0071] Next, at time t3, a predetermined calculation time after time t2 when proximity sensor 31A turned ON, control unit 6 determines that second bellows 14 has reached its fully contracted state. Control unit 6 then de-energizes solenoid 5a of second solenoid valve 5 and energizes solenoid 5b. When solenoid 5b of second solenoid valve 5 is energized, pressurized air generated by air supply device 2 is supplied to second suction-side air chamber 26B of second drive unit 28 via mechanical regulator 3, second electropneumatic regulator 52, and second solenoid valve 5. This causes second drive unit 28 to actively extend second bellows 14, which is in its fully contracted state.

[0072] At this time, the control unit 6 controls the speed at which the second bellows 14 is extended by the second drive unit 28 so that the time difference (t5-t4) from time t4 to time t5, which will be described later, becomes a second time T20 (e.g., 30 msec to 60 msec), thereby advancing or delaying time t4. Specifically, while the second bellows 14 is being actively driven to extend from time t3 to time t4, the control unit 6 outputs a control command to the second electropneumatic regulator 52, causing the second electropneumatic regulator 52 to adjust the air pressure of the pressurized air supplied to the second suction-side air chamber 26B. In this way, the speed at which the second bellows 14 is extended by the second drive unit 28 is controlled.

[0073] Next, at time t4 when the proximity sensor 31B detects (ON) that the second bellows 14 is in the second mid-extension state, the control unit 6 demagnetizes the solenoid 5b of the second solenoid valve 5. This causes the second drive unit 28 to stop the active extension drive of the second bellows 14 in the second mid-extension state. When the active extension drive of the second bellows 14 stops, the transfer fluid is no longer sucked in within the second bellows 14, changing the flow of the transfer fluid, generating an impact pressure. This impact pressure causes a pressure increase within the second bellows 14.

[0074] Due to the pressure increase within the second bellows 14, the second bellows 14 passively expands from the second intermediate expansion state within the second time T20. Here, the second bellows 14 passively expands to the fully expanded state. By passively expanding the second bellows 14 in this manner, the pressure increase in the second bellows 14 can be absorbed before the second time T20 has elapsed.

[0075] Next, at time t5 when proximity sensor 29A detects (ON) that first bellows 13 is in the first mid-deflation state, control unit 6 energizes solenoid 5a of second solenoid valve 5. Pressurized air generated by air supply device 2 is then supplied to second discharge-side air chamber 21B of second drive unit 28 via mechanical regulator 3, second electropneumatic regulator 52, and second solenoid valve 5. As a result, second drive unit 28 begins actively driving second bellows 14, which is in the fully extended state, to contract just before first bellows 13 reaches the fully contracted state. As a result, both first bellows 13 and second bellows 14 are driven to contract.

[0076] Next, at time t6, a predetermined calculation time after time t5 when proximity sensor 29A turned ON, control unit 6 determines that first bellows 13 has reached its fully contracted state. Then, control unit 6 demagnetizes solenoid 4a and magnetizes solenoid 4b of first solenoid valve 4. When solenoid 4b is energized, first drive unit 27, as described above, begins actively driving first bellows 13, which is in its fully contracted state, to extend it.

[0077] After this, the control unit 6 repeatedly performs the control performed at each of the above-mentioned times t0 to t6, thereby controlling the bellows pump 10 so that the contraction drive of the first bellows 13 (second bellows 14) starts just before the second bellows 14 (first bellows 13) reaches its maximum contraction state, while absorbing the pressure increase in the first bellows 13 (second bellows 14) due to the impact pressure.

[0078] [Effects of this embodiment] As described above, according to the bellows pump device 1 of this embodiment, the control unit 6 starts driving the first bellows 13 (second bellows 14) to contract when the second bellows 14 (first bellows 13) reaches the second mid-contraction state (first mid-contraction state) before the fully contracted state. This allows the first bellows 13 (second bellows 14) to already discharge the transferred fluid when the second bellows 14 (first bellows 13) switches from discharge to suction, thereby reducing a drop in the discharge pressure of the transferred fluid at the switching timing. As a result, pulsation on the discharge side of the bellows pump 10 can be reduced.

[0079] Furthermore, the control unit 6 stops the active extension drive of the first bellows 13 (second bellows 14) at a first mid-extension state (second mid-extension state) that is just before the fully extended state. Therefore, even if a pressure rise occurs in the first bellows 13 (second bellows 14) due to impact pressure when the extension drive of the first bellows 13 (second bellows 14) is stopped, the first bellows 13 (second bellows 14) passively extends from the first mid-extension state (second mid-extension state), thereby absorbing the pressure rise. This makes it possible to suppress the impact pressure that occurs when switching from suction to discharge of the transport fluid.

[0080] Furthermore, in the first mid-extension state (second mid-extension state), an extension margin is ensured that allows the first bellows 13 (second bellows 14) to passively extend, and this passive extension can effectively absorb the pressure increase within the first bellows 13 (second bellows 14). As a result, the impact pressure can be further suppressed.

[0081] Furthermore, the time difference between when the active expansion drive of the first bellows 13 (second bellows 14) is stopped in the first mid-expansion state (second mid-expansion state) and when the contraction drive of the first bellows 13 (second bellows 14) is started is controlled to be the first time T10 (second time T20), which is the passive expansion time of the first bellows 13 (second bellows 14). Therefore, the passive expansion of the first bellows 13 (second bellows 14) can be reliably completed within the first time T10 (second time T20). As a result, when the second bellows 14 (first bellows 13) enters the second mid-contraction state (first mid-contraction state), the contraction drive of the first bellows 13 (second bellows 14) can be immediately started, thereby effectively reducing the pulsation on the discharge side of the bellows pump 10 while suppressing the impact pressure.

[0082] [others] Although the first detection unit 29 and the second detection unit 31 in the above embodiment detect the mid-extension and mid-contraction states of the bellows 13, 14, they may be configured to detect other expansion / contraction states. Furthermore, the first detection unit 29 and the second detection unit 31 are not limited to the proximity sensors 29A, 29B, 31A, 31B in the above embodiment. For example, the first detection unit 29 and the second detection unit 31 may be configured as a displacement sensor using laser light or the like. Although the first drive unit 27 and the second drive unit 28 in the present embodiment are driven by pressurized air, they may be driven by other fluids.

[0083] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include any modifications within the scope of the claims and meaning equivalent to the claims. [Explanation of symbols]

[0084] 1 Bellows pump device 6 Control Unit 13 First Bellows 14 Second Bellows 27 First drive unit 28 Second drive unit 29 First detection unit 31 Second detection unit T10 1st Hour T20 2nd Hour

Claims

1. a first bellows and a second bellows that are independently expandable between a fully expanded state and a fully contracted state, and that draw in a transfer fluid when expanded and discharge the transfer fluid when contracted; a first driving unit that actively drives the first bellows to expand and contract; a second driving unit that actively drives the second bellows to expand and contract; a first detection unit that detects the expansion / contraction state of the first bellows; a second detection unit that detects the expansion / contraction state of the second bellows; a control unit that controls the operation of the first drive unit and the second drive unit based on detection signals from the first detection unit and the second detection unit so that the extension drive of the first bellows is stopped at a first intermediate extension state that is shorter than the maximum extension state, and then the contraction drive of the first bellows is started just before the second bellows reaches the maximum contraction state, and the extension drive of the second bellows is stopped at a second intermediate extension state that is shorter than the maximum extension state, and then the contraction drive of the second bellows is started just before the first bellows reaches the maximum contraction state.

2. the first mid-extension state is a state in which an extension margin is secured that allows the first bellows to passively extend due to a pressure increase within the first bellows, 2. The bellows pump device according to claim 1, wherein the second mid-extension state is a state in which an extension margin is secured that allows the second bellows to passively extend due to a pressure increase within the second bellows.

3. 3. The bellows pump device according to claim 2, wherein the control unit controls the operation so that a time difference between stopping the expansion drive of the first bellows in the first mid-expansion state and starting the contraction drive of the first bellows is equal to or greater than a first time period defined below, and a time difference between stopping the expansion drive of the second bellows in the second mid-expansion state and starting the contraction drive of the second bellows is equal to or greater than a second time period defined below. First time: the time it takes for the first bellows to passively expand due to a pressure increase in the first bellows Second time: the time it takes for the second bellows to passively expand due to a pressure increase in the second bellows

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