Bellows Pump Device

Abstract

To provide a bellows pump which can determine an occurrence of an abnormality in a fluid pressure adjustment section with an inexpensive constitution.SOLUTION: A control unit 6 of a bellows pump device 1 determines whether or not a second bellows 14 (a first bellows 13) is partway through expansion when the first bellows 13 (the second bellows 14) has contracted to a mid-contraction state. When the result of the determination is affirmative, the control unit performs pressure rise control, which outputs a pressure rise command to a second electropneumatic regulator 52 (a first electropneumatic regulator 51) so as to raise a pneumatic pressure of compressed air supplied to a second suction-side air chamber 26B (a first suction-side air chamber 26A) of a second drive unit 28 (a first drive unit 27) during the next expansion of the second bellows 14 (the first bellows 13). The control unit 6 counts the number of times pressure rise control is performed consecutively, and when the counted number of times exceeds a prescribed number of times, the control unit determine that an abnormality has occurred in the second electropneumatic regulator 52 (the first electropneumatic regulator 51).SELECTED DRAWING: Figure 7

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, and the like include the bellows pump described in Patent Document 1. The bellows pump described in Patent Document 1 includes 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. This bellows pump controls the drive of each air cylinder so that just before one bellows is fully contracted (discharge completed), 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 above-mentioned bellows pump, one bellows must be fully extended (suction completed) before the other bellows is fully contracted (discharge completed). However, changes in the ambient temperature or the flow rate of the transported fluid affect the hardness of the bellows. When the hardness of the bellows changes, the bellows' extension time (suction time) changes, which can adversely affect the bellows pump by worsening pulsation on the discharge side or causing impact pressure known as "water hammer" or cavitation.

[0006] Therefore, the present applicant has proposed a bellows pump device that automatically resets the air pressure of the pressurized air supplied to the air chamber of the air cylinder to an appropriate value using an electropneumatic regulator so that the bellows expansion time is appropriate (International Application No. PCT / JP2021 / 034699). In this bellows pump device, if one bellows has contracted to a mid-contraction state but the other bellows has not yet expanded to a predetermined extended state, the control unit performs pressure increase control to increase the air pressure of the pressurized air supplied to the air chamber of the air cylinder the next time the other bellows is expanded. Also, if one bellows has contracted to a mid-contraction state but the other bellows has maintained the predetermined extended state for a predetermined time or more, the control unit performs pressure decrease control to decrease the air pressure of the pressurized air supplied to the air chamber of the air cylinder the next time the other bellows is expanded.

[0007] However, if an abnormality such as a breakdown occurs in the electro-pneumatic regulator, the electro-pneumatic regulator is generally designed to maintain the air pressure adjusted immediately before the abnormality occurred. Therefore, pressurized air at the air pressure adjusted immediately before the abnormality occurs is constantly supplied to the air cylinder, and this pressurized air causes the bellows to continue to expand and contract. If the bellows continue to expand and contract in this way, the bellows extension time will change, which may have an adverse effect on the bellows pump as described above. One possible solution to this problem is to monitor the air pressure of the electro-pneumatic regulator. However, in this case, it would be necessary to connect a separate line to monitor the air pressure or a pressure gauge to detect the air pressure to the output line of the electro-pneumatic regulator, which would increase costs.

[0008] The present disclosure has been made in consideration of the above circumstances, and aims to provide a bellows pump device that is inexpensively configured and that is capable of detecting the occurrence of an abnormality in a fluid pressure adjustment section. [Means for solving the problem]

[0009] (1) The present disclosure provides a device comprising: a pair of bellows that are independently expandable and contractible, sucking transfer fluid into the interior when expanded and discharging transfer fluid from the interior when contracted; a pair of drive units having an intake-side fluid chamber and a discharge-side fluid chamber, and supplying pressurized fluid to the intake-side fluid chamber to expand each of the bellows to a predetermined expanded state, and supplying pressurized fluid to the discharge-side fluid chamber to contract each of the bellows to a predetermined contracted state; a pair of fluid pressure adjustment units that adjust the fluid pressure of the pressurized fluid supplied to the intake-side fluid chamber of each of the drive units; a pair of detection units that detects the expansion / contraction state of each of the bellows; and a control unit that controls the pair of drive units and the pair of fluid pressure adjustment units based on detection signals from the pair of detection units, wherein the control unit controls the pair of the bellows. The bellows pump device includes: a drive control that controls the pair of drive units so that one bellows contracts from the extended state just before the other bellows reaches the contracted state; a pressure increase determination that determines whether the other bellows is in the process of extension when the one bellows contracts to a mid-contraction state just before the other bellows reaches the contracted state, and a pressure increase control that outputs a pressure increase command to the fluid pressure adjustment unit corresponding to the drive unit that extends the other bellows so as to increase the fluid pressure the next time the other bellows is extended; and the number of consecutive pressure increase controls that have been performed is counted, and if the counted number exceeds a predetermined number, it is determined that the fluid pressure adjustment unit is abnormal.

[0010] In the bellows pump device of the present disclosure, if an abnormality occurs in the fluid pressure adjustment unit and the fluid pressure adjustment unit maintains the fluid pressure adjusted immediately before the abnormality occurred, the fluid pressure adjustment unit will be unable to increase the fluid pressure even if the control unit outputs a pressure increase command to the fluid pressure adjustment unit. As a result, the control unit will repeatedly output pressure increase commands to the fluid pressure adjustment unit. The present inventors focused on this point and completed the present disclosure. Specifically, the control unit counts the number of consecutive pressure increase control operations and determines that the fluid pressure adjustment unit is abnormal if the counted number exceeds a predetermined number. This makes it possible to determine that an abnormality has occurred in the fluid pressure adjustment unit using an inexpensive configuration that does not require a pressure gauge or the like.

[0011] (2) From another perspective, the present disclosure provides a pair of bellows that are expandable and contractable independently of each other, that draw in a transfer fluid when expanded and that discharge the transfer fluid when contracted; a pair of drive units having an intake-side fluid chamber and a discharge-side fluid chamber, that expand each of the bellows to a predetermined expanded state by supplying pressurized fluid to the intake-side fluid chamber and that contract each of the bellows to a predetermined contracted state by supplying pressurized fluid to the discharge-side fluid chamber; a pair of fluid pressure adjustment units that adjust the fluid pressure of the pressurized fluid supplied to the intake-side fluid chamber of each of the drive units; a pair of detection units that detect the expansion / contraction states of each of the bellows; and a control unit that controls the pair of drive units and the pair of fluid pressure adjustment units based on detection signals from the pair of detection units, wherein the control unit selects one of the pair of bellows. This bellows pump device performs a drive control that controls the pair of drive units so as to contract one bellows from the extended state just before the other bellows reaches the contracted state, and a pressure reduction determination that determines whether the other bellows continues to be in the extended state for a predetermined time or more when the one bellows has contracted to a mid-contraction state just before reaching the contracted state, and if the determination result of the pressure reduction determination is positive, outputs a pressure reduction command to the fluid pressure adjustment unit corresponding to the drive unit that extends the other bellows so as to reduce the fluid pressure the next time the other bellows is extended, and counts the number of consecutive times the pressure reduction control is performed, and if the counted number exceeds a predetermined number, determines that the fluid pressure adjustment unit is abnormal.

[0012] In the bellows pump device of the present disclosure, if an abnormality occurs in the fluid pressure adjustment unit and the fluid pressure adjustment unit maintains the fluid pressure adjusted immediately before the abnormality occurred, the fluid pressure adjustment unit will be unable to reduce the fluid pressure even if the control unit outputs a pressure reduction command to the fluid pressure adjustment unit. As a result, the control unit will repeatedly output pressure reduction commands to the fluid pressure adjustment unit. The present inventors focused on this point and completed the present disclosure. Specifically, the control unit counts the number of consecutive pressure reduction controls and determines that the fluid pressure adjustment unit is abnormal if the counted number exceeds a predetermined number. This makes it possible to determine that an abnormality has occurred in the fluid pressure adjustment unit using an inexpensive configuration that does not require a pressure gauge or the like.

[0013] (3) In the bellows pump device of (1), when one of the bellows has contracted to the mid-contraction state, the control unit preferably performs a pressure reduction determination to determine whether the other bellows has maintained the expanded state for a predetermined time or longer, and if the result of the pressure reduction determination is positive, further performs pressure reduction control to output a pressure reduction command to the fluid pressure adjustment unit corresponding to the drive unit that extends the other bellows so as to reduce the fluid pressure the next time the other bellows is expanded, counts the number of consecutive pressure reduction controls, and determines that the fluid pressure adjustment unit is abnormal if either the number of consecutive pressure increase controls or the number of consecutive pressure reduction controls exceeds a predetermined number. In this case, whether the pressure increase control is continuously performed or the pressure decrease control is continuously performed, it is possible to know that an abnormality has occurred in the fluid pressure adjusting section.

[0014] (4) In the bellows pump device of (1) or (3), it is preferable that the control unit counts the number of times the pressure increase determination result is consecutively positive as the number of times the pressure increase control has been performed consecutively. In this case, the control unit can determine that the number of consecutive pressure increase control operations has exceeded a predetermined number before outputting a pressure increase command to the fluid pressure adjustment unit, thereby quickly detecting that an abnormality has occurred in the fluid pressure adjustment unit.

[0015] (5) In the bellows pump device of (2) or (3), it is preferable that the control unit counts the number of times the pressure reduction determination result is consecutively positive as the number of times the pressure reduction control has been performed consecutively. In this case, the control unit can determine that the number of times that pressure reduction control has been performed consecutively exceeds a predetermined number before outputting a pressure reduction command to the fluid pressure adjustment unit, thereby quickly detecting that an abnormality has occurred in the fluid pressure adjustment unit. [Effects of the Invention]

[0016] According to the bellows pump device of the present disclosure, it is possible to detect the occurrence of an abnormality in the fluid pressure adjusting section with an inexpensive configuration. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic configuration diagram of a bellows pump device according to an embodiment. [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 voltage boost control. [Figure 6] 4 is a time chart showing an example of voltage step-down control. [Figure 7] 10 is a flowchart illustrating an example of abnormality determination. DETAILED DESCRIPTION OF THE INVENTION

[0018] Next, preferred embodiments will be described with reference to the accompanying drawings. [Overall configuration] 1 is a schematic diagram of a bellows pump device 1 according to an embodiment. The bellows pump device 1 of this embodiment is used, for example, in semiconductor manufacturing equipment to supply a constant amount of transfer fluid such as a chemical solution or a solvent. 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 (fluid pressure adjustment unit) 51, and a second electropneumatic regulator (fluid pressure adjustment unit) 52.

[0019] 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 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.

[0020] 2 is a cross-sectional view of a bellows pump 10 according to this embodiment. 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.

[0021] [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-perfluoroalkyl vinyl ether copolymer (PFA). Flanges 13a and 14a formed integrally at the open ends of the first and second bellows 13, 14 are fixed by being pressed airtight against the side of the pump head 11. The peripheral walls of the first and second bellows 13, 14 are formed in a bellows shape and are configured to be able to expand and contract in the left-right direction independently of each other.

[0022] An actuating plate 19 is fixed to the outer surfaces of the closed end portions of the first and second bellows 13, 14 by bolts 17 and nuts 18. The first and second bellows 13, 14 can expand and contract between a fully extended state in which the outer surface of the actuating plate 19 abuts against the inner surface of a bottom wall portion 121 of the cylindrical pump case 12 with a bottom, and a fully 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.

[0023] [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 (discharge-side fluid chamber) 21A that is kept airtight is formed outside first bellows 13 inside first pump case 12A.

[0024] 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). When pressurized air is supplied from the air supply device 2 to the inside of the first discharge air chamber 21A, the first bellows 13 contracts to a predetermined contracted state (hereinafter simply referred to as the "contracted state"). The contracted state of the first bellows 13 may be the fully contracted state or a state just before the fully contracted state.

[0025] 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 (discharge-side fluid chamber) 21B that is kept airtight is formed outside second bellows 14 inside second pump case 12B.

[0026] 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 to a predetermined contracted state (hereinafter simply referred to as the "contracted state"). The contracted state of the second bellows 14 may be the fully contracted state or a state just before the fully contracted state.

[0027] 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.

[0028] As a result, on the first pump case 12A side, the space surrounded by the bottom wall 121, the cylinder body 25, and the piston body 23 is made into a first suction side air chamber (suction side fluid chamber) 26A that is kept airtight. On the second pump case 12B side, the space surrounded by the bottom wall 121, the cylinder body 25, and the piston body 23 is made into a second suction side air chamber (suction side fluid chamber) 26B that is kept airtight.

[0029] 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). 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 to a predetermined expanded state (hereinafter simply referred to as the "expanded state"). The expanded state of the first bellows 13 may be the fully expanded state or a state before the fully expanded state.

[0030] 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 to a predetermined expanded state (hereinafter simply referred to as the "expanded state"). The expanded state of the second bellows 14 may be the fully expanded state or a state just before the fully expanded state.

[0031] 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 a first drive unit (drive unit) 27 that continuously expands and contracts the first bellows 13 between an extended state and a contracted state. In addition, the second pump case 12B, which has the second discharge side air chamber 21B formed therein, and the piston body 23 and cylinder body 25, which form the second suction side air chamber 26B, constitute a second drive unit (drive unit) 28 that continuously expands and contracts the second bellows 14 between an extended state and a contracted state.

[0032] [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.

[0033] Proximity sensor 29A is disposed in a position where it detects detectable plate 30 when first bellows 13 is in a partially contracted state just before it enters a contracted state. Proximity sensor 29B is disposed in a position where it detects detectable plate 30 when first bellows 13 is in an 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 (detection unit) 29 that detects the expansion / contraction state of first bellows 13.

[0034] 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.

[0035] Proximity sensor 31A is positioned to detect detectable plate 32 when second bellows 14 is in a partially contracted state just before it enters a contracted state. Proximity sensor 31B is positioned to detect detectable plate 32 when second bellows 14 is in an extended state. When each proximity sensor 31A, 31B detects detectable plate 32, it outputs a detection signal to control unit 6. The pair of proximity sensors 31A, 31B function as second detection unit (detection unit) 31 that detects the expansion / contraction state of second bellows 14.

[0036] Here, the "mid-contraction state" of the first bellows 13 (second bellows 14) means that the position of the first bellows 13 (second bellows 14) during the contraction process is closer to the end position (contracted state) of contraction than to the start position (extended state), and more specifically, means the position where the first bellows 13 (second bellows 14) has contracted to 50% to 90% of the contraction length from the extended state to the contracted state.

[0037] [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.

[0038] 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. 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. The suction ports 36 and the discharge ports 37 communicate with the interiors of the bellows 13 and 14 via check valves 15 and 16, respectively.

[0039] [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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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).

[0045] [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, the valve elements 15b, 16b of the suction check valve 15 and the discharge check valve 16 mounted on the left side of the pump head 11 in the figure are subjected to pressure from the transferred fluid in the first bellows 13 and move to the right side of the valve cases 15a, 16a in the figure. This closes the suction check valve 15 and opens the discharge check valve 16, causing the transferred fluid in the first bellows 13 to be discharged from the discharge passage 35 to the outside of the pump.

[0046] 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.

[0047] 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 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.

[0048] 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.

[0049] [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 a first drive unit 27, between supplying and discharging pressurized air to and from the first discharge-side air chamber 21A and the first suction-side air chamber 26A.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] [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 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.

[0054] 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 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.

[0055] The electropneumatic regulators 51, 52 may be any regulator that adjusts the air pressure of the pressurized air supplied to at least the suction-side air chambers 26A, 26B. In this embodiment, the electropneumatic regulators 51, 52 that directly adjust the air pressure are used as the fluid pressure adjusters, but the air pressure may be indirectly adjusted using an air flow rate adjustment valve that adjusts the air flow rate, or a device that adjusts the pressure or flow rate of a gas other than air (for example, nitrogen) or liquid may be used.

[0056] [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 first drive unit 27, the second drive unit 28, the first electropneumatic regulator 51, and the second electropneumatic regulator 52 based on the detection results of the first detection unit 29 and the second detection unit 31. These controls will be explained below in order.

[0057] The control unit 6 performs drive control to control the first drive unit 27 and the second drive unit 28, respectively, by switching the first solenoid valve 4 and the second solenoid valve 5 based on the detection results of the first detection unit 29 and the second detection unit 31.

[0058] Specifically, based on the detection results of the first detection unit 29 and the second detection unit 31, the control unit 6 controls the driving of the first drive unit 27 and the second drive unit 28 so that the second bellows 14 contracts from an extended state just before the first bellows 13 reaches a contracted state, and so that the first bellows 13 contracts from an extended state just before the second bellows 14 reaches a contracted state.

[0059] By controlling the drive as described above by the control unit 6, when one of the first bellows 13 and the second bellows 14 switches from contraction to expansion (from discharging to suctioning the transferred fluid), the other bellows has already contracted and is discharging the transferred fluid, so that a large drop in the discharge pressure of the transferred fluid at that time can be reduced. As a result, pulsation on the discharge side of the bellows pump 10 can be reduced.

[0060] In the drive control, for example, if the ambient temperature drops, the first bellows 13 and the second bellows 14 may become hard due to the effect, and the extension time of each of the first bellows 13 and the second bellows 14 may become longer. In this case, the control unit 6 performs pressure increase control to shorten the extension time of each of the first bellows 13 and the second bellows 14 based on the detection results of the first detection unit 29 and the second detection unit 31. As the pressure increase control, the control unit 6 performs a pressure increase determination and outputs a pressure increase command based on the determination result.

[0061] Specifically, the control unit 6 performs a pressure increase determination to determine whether the second bellows 14 (first bellows 13) is in the middle of expanding when the first bellows 13 (second bellows 14) has contracted to a mid-contraction state, based on the detection results of the first detection unit 29 and the second detection unit 31. If the determination result of the pressure increase determination is affirmative (the second bellows 14 is in the middle of expanding), the control unit 6 outputs a pressure increase command to the second electropneumatic regulator 52 (first electropneumatic regulator 51) to increase the air pressure of the pressurized air supplied to the second suction-side air chamber 26B (first suction-side air chamber 26A) the next time the second bellows 14 (first bellows 13) expands. The pressure increase command includes the degree of increase in the air pressure. This pressure increase degree is preferably between +1 kPa and +50 kPa (more preferably between +1 kPa and +20 kPa).

[0062] On the other hand, in the drive control, for example, if the ambient temperature rises, the first bellows 13 and the second bellows 14 may become softer and the extension times of the first bellows 13 and the second bellows 14 may become shorter. In this case, the control unit 6 performs pressure reduction control to increase the extension times of the first bellows 13 and the second bellows 14 based on the detection results of the first detection unit 29 and the second detection unit 31. As the pressure reduction control, the control unit 6 performs a pressure reduction determination and outputs a pressure reduction command based on the determination result.

[0063] Specifically, the control unit 6 performs a pressure drop determination to determine whether the second bellows 14 (first bellows 13) has remained in an expanded state for a predetermined time or longer when the first bellows 13 (second bellows 14) has contracted to a mid-contraction state, based on the detection results of the first detection unit 29 and the second detection unit 31. The predetermined time is desirably set to a value of, for example, 500 msec (preferably 10 to 200 msec).

[0064] If the result of the pressure reduction determination is affirmative (the expanded state has continued for a predetermined time or longer), the control unit 6 outputs a pressure reduction command to the second electropneumatic regulator 52 (first electropneumatic regulator 51) to reduce the air pressure of the pressurized air supplied to the second suction-side air chamber 26B (first suction-side air chamber 26A) the next time the second bellows 14 (first bellows 13) is expanded. The pressure reduction command includes the degree of reduction in the air pressure. This degree of reduction is preferably between -1 kPa and -50 kPa (more preferably between -1 kPa and -20 kPa).

[0065] [Example of boost control] Fig. 5 is a time chart showing an example of pressure increase control performed during drive control by the control unit 6. The drive control and pressure increase 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 a state in which the first bellows 13 is in the middle of contracting (discharging) and the second bellows 14 is in the middle of expanding (sucking).

[0066] At time t1 when proximity sensor 29A detects (ON) that the first bellows 13 is in the middle of contraction, control unit 6 determines whether or not the second bellows 14 is in the middle of expansion (pressure increase determination). This determination is made based on whether or not proximity sensor 31B is not detecting (OFF) the expansion state of the second bellows 14 at time t1. Here, because proximity sensor 31B is not detecting the expansion state of the second bellows 14 at time t1, control unit 6 determines that the second bellows 14 is in the middle of expansion. Based on this determination result, control unit 6 outputs a pressure increase command the next time the second bellows 14 is expanded (between time t6 and time t7), as described below.

[0067] If the control unit 6 determines that the proximity sensor 31B is not ON, it waits until the proximity sensor 31B is turned ON. Then, at time t2 when the proximity sensor 31B is turned ON, the control unit 6 demagnetizes the solenoid 5b of the second solenoid valve 5 and magnetizes the solenoid 5a. If the control unit 6 determines that the proximity sensor 31B is ON at time t1, it immediately demagnetizes the solenoid 5b of the second solenoid valve 5 and magnetizes the solenoid 5a.

[0068] When the solenoid 5a of the second solenoid valve 5 is excited, the pressurized air generated by the air supply device 2 is supplied to the second discharge air chamber 21B of the second drive unit 28 via the mechanical regulator 3, the second electropneumatic regulator 52, and the second solenoid valve 5. At this time, the control unit 6 outputs a control command to the second electropneumatic regulator 52 so that the air pressure of the pressurized air supplied to the second discharge air chamber 21B reaches a predetermined value P2. As a result, the second bellows 14 begins to contract from the extended state before the first bellows 13 enters the contracted state.

[0069] After the second bellows 14 starts to contract, the control unit 6 determines that the first bellows 13 has contracted at time t3, a predetermined calculation time after time t1 when the proximity sensor 29A turns ON. Then, the control unit 6 demagnetizes the solenoid 4a of the first solenoid valve 4 and magnetizes the solenoid 4b.

[0070] When the solenoid 4b of the first solenoid valve 4 is excited, the 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. At this time, the control unit 6 outputs a control command to the first electropneumatic regulator 51 so that the air pressure of the pressurized air supplied to the first suction-side air chamber 26A becomes a predetermined value P11. Based on the control command, the first electropneumatic regulator 51 adjusts the air pressure of the pressurized air supplied to the first suction-side air chamber 26A so that it becomes the predetermined value P11. As a result, the first bellows 13 begins to expand from its contracted state.

[0071] Next, at time t4 when proximity sensor 31A detects (ON) that the second bellows 14 is in the middle of contraction, control unit 6 determines whether or not the first bellows 13 is in the middle of expansion (pressure increase determination). This determination is made based on whether proximity sensor 29B is not detecting (OFF) that the first bellows 13 is in the middle of expansion at time t4. Here, because proximity sensor 29B is not detecting the expansion state of the first bellows 13 at time t4, control unit 6 determines that the first bellows 13 is in the middle of expansion. Based on this determination result, control unit 6 outputs a pressure increase command the next time the first bellows 13 is expanded (from time t8 to time t9), as will be described later.

[0072] If the control unit 6 determines that the proximity sensor 29B is not ON, it waits until the proximity sensor 29B is turned ON. Then, at time t5 when the proximity sensor 29B is turned ON, the control unit 6 demagnetizes the solenoid 4b of the first solenoid valve 4 and magnetizes the solenoid 4a. If the control unit 6 determines that the proximity sensor 29B is ON at time t4, it immediately demagnetizes the solenoid 4b of the first solenoid valve 4 and magnetizes the solenoid 4a.

[0073] When the solenoid 4a of the first solenoid valve 4 is excited, the pressurized air generated by the air supply device 2 is supplied to the first discharge air chamber 21A of the first drive unit 27 via the mechanical regulator 3, the first electropneumatic regulator 51, and the first solenoid valve 4. At this time, the control unit 6 outputs a control command to the first electropneumatic regulator 51 so that the air pressure of the pressurized air supplied to the first discharge air chamber 21A becomes a predetermined value P1. Based on the control command, the first electropneumatic regulator 51 adjusts the air pressure of the pressurized air supplied to the first discharge air chamber 21A so that it becomes the predetermined value P1. As a result, the first bellows 13 starts to contract from the extended state just before the second bellows 14 becomes contracted.

[0074] After the first bellows 13 starts to contract, the control unit 6 determines that the second bellows 14 has contracted at time t6, a predetermined time after the proximity sensor 31A turned ON. The control unit 6 then demagnetizes the solenoid 5a of the second solenoid valve 5 and magnetizes the solenoid 5b.

[0075] When the solenoid 5b of the second solenoid valve 5 is excited, the pressurized air generated by the air supply device 2 is supplied to the second suction-side air chamber 26B of the second drive unit 28 via the mechanical regulator 3, the second electropneumatic regulator 52, and the second solenoid valve 5. At this time, because the result of the pressure increase determination made by the control unit 6 at time t1 was positive (because the control unit 6 determined that the proximity sensor 31B was not detecting anything), the control unit 6 outputs a pressure increase command to the second electropneumatic regulator 52 to increase the air pressure of the pressurized air supplied to the second suction-side air chamber 26B.

[0076] Specifically, the control unit 6 outputs a pressure increase command to the second electropneumatic regulator 52 so that the air pressure of the pressurized air supplied to the second suction-side air chamber 26B becomes a value P22 that is higher than the previous value P21 (before time t2). Based on the pressure increase command, the second electropneumatic regulator 52 adjusts the air pressure of the pressurized air supplied to the second suction-side air chamber 26B to the value P22. As a result, the second bellows 14 begins to expand from its contracted state. The expansion speed is faster than the previous expansion speed of the second bellows 14.

[0077] Next, at time t7 when proximity sensor 29A detects (ON) that the first bellows 13 is in the middle of contraction, control unit 6 determines whether the second bellows 14 is in the middle of expansion (pressure increase determination). Here, as described above, the expansion speed of the second bellows 14 increases and the expansion time of the second bellows 14 shortens, so that the second bellows 14 reaches the expanded state at time t7. Therefore, since proximity sensor 31B detects (ON) that the second bellows 14 is in the expanded state at time t7, control unit 6 determines that the second bellows 14 is not in the middle of expansion. Based on this determination result, control unit 6 does not output a pressure increase command the next time the second bellows 14 is expanded.

[0078] When the control unit 6 determines that the proximity sensor 29B is ON, it demagnetizes the solenoid 5b and magnetizes the solenoid 5a of the second solenoid valve 5. When the solenoid 5a of the second solenoid valve 5 is excited, as described above, the second bellows 14 starts contracting from the extended state just before the first bellows 13 enters the contracted state (in the middle of contraction).

[0079] After the second bellows 14 starts to contract, at time t8, a predetermined calculation time after time t7 when the proximity sensor 29A turns ON, the control unit 6 determines that the first bellows 13 has contracted, and demagnetizes the solenoid 4a and magnetizes the solenoid 4b of the first solenoid valve 4. When the solenoid 4b of the first solenoid valve 4 is magnetized, the 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, as described above.

[0080] At that time, since the result of the pressure increase determination performed at time t4 was positive (the proximity sensor 29B was determined to be non-detecting), the control unit 6 outputs a pressure increase command to the first electro-pneumatic regulator 51 to increase the air pressure of the pressurized air supplied to the first suction side air chamber 26A.

[0081] Specifically, the control unit 6 outputs a pressure increase command to the first electropneumatic regulator 51 so that the air pressure of the pressurized air supplied to the first suction-side air chamber 26A becomes a value P12, which is higher than the previous value P11 (from time t3 to time t5). Based on the pressure increase command, the first electropneumatic regulator 51 adjusts the air pressure of the pressurized air supplied to the first suction-side air chamber 26A to the value P12. As a result, the first bellows 13 begins to expand from its contracted state. The expansion speed is faster than the expansion speed during the previous expansion operation of the first bellows 13.

[0082] Next, at time t9 when proximity sensor 31A detects (ON) that second bellows 14 is in the middle of contraction, control unit 6 determines whether first bellows 13 is in the middle of expansion (pressure increase determination). Here, as described above, the expansion speed of first bellows 13 increases and the expansion time of first bellows 13 shortens, so that first bellows 13 reaches the expanded state at time t9. Therefore, since proximity sensor 29B detects (ON) that first bellows 13 is in the expanded state at time t9, control unit 6 determines that first bellows 13 is not in the middle of expansion. Based on this determination result, control unit 6 does not output a pressure increase command the next time first bellows 13 is expanded.

[0083] When the control unit 6 determines that the proximity sensor 29B is ON, it demagnetizes the solenoid 4b and magnetizes the solenoid 4a of the first solenoid valve 4. When the solenoid 4a of the first solenoid valve 4 is excited, as described above, the first bellows 13 starts contracting from the extended state just before the second bellows 14 enters the contracted state (in the mid-contraction state).

[0084] [Example of step-down control] Fig. 6 is a time chart showing an example of pressure reduction control performed by the control unit 6 during drive control. Below, the pressure reduction control performed by the control unit 6 will be explained with reference to Fig. 1 and Fig. 6. Here, as with Fig. 5, the explanation will start from a state in which the first bellows 13 is in the middle of contracting (discharging) and the second bellows 14 is in the middle of expanding (sucking).

[0085] The control unit 6 determines whether the proximity sensor 31B has detected (ON) the expanded state of the second bellows 14 before the proximity sensor 29A has detected (ON) the mid-contraction state of the first bellows 13. Here, the proximity sensor 31B has detected the expanded state of the second bellows 14 at time t20 before the first bellows 13 reaches the mid-contraction state, so the control unit 6 determines that the proximity sensor 31B has turned ON.

[0086] When it is determined that the proximity sensor 31B has turned ON, the control unit 6 further determines, at time t21 when the proximity sensor 29A detects the first bellows 13 in the middle of contraction, whether or not the predetermined time T has continued since time t20 when the proximity sensor 31B detected the second bellows 14 in the expanded state (pressure drop determination). In this case, the predetermined time T has passed at time t21, so the control unit 6 determines that the predetermined time T has continued since time t20. Based on this determination result, the control unit 6 outputs a pressure drop command the next time the second bellows 14 is expanded (from time t25 to time t26), as will be described later.

[0087] At time t21 when the proximity sensor 29A turns ON, the control unit 6 demagnetizes the solenoid 5b and magnetizes the solenoid 5a of the second solenoid valve 5. When the solenoid 5a of the second solenoid valve 5 is excited, as described above, the second bellows 14 starts contracting from the extended state just before the first bellows 13 enters the contracted state (in the middle of contraction).

[0088] After the second bellows 14 starts to contract, the control unit 6 determines that the first bellows 13 has entered the contracted state at time t22, a predetermined calculation time after time t21 when the proximity sensor 29A turns ON. The control unit 6 then demagnetizes the solenoid 4a and magnetizes the solenoid 4b of the first solenoid valve 4. When the solenoid 4b of the first solenoid valve 4 is magnetized, the first bellows 13 starts to expand from the contracted state, as described above.

[0089] Next, the control unit 6 determines whether the proximity sensor 29B has detected (ON) the expanded state of the first bellows 13 before the proximity sensor 31A has detected (ON) the mid-contraction state of the second bellows 14. Here, the proximity sensor 29B has detected the expanded state of the first bellows 13 at time t23 before the second bellows 14 reaches the mid-contraction state, so the control unit 6 determines that the proximity sensor 29B has turned ON.

[0090] When it is determined that proximity sensor 29B has turned ON, at time t24 when proximity sensor 31A detects that second bellows 14 is in the middle of contraction, control unit 6 further determines whether or not a predetermined time T or more has continued since time t23 when proximity sensor 29B detected that first bellows 13 was in the expanded state (pressure drop determination). In this case, since the predetermined time T has passed at time t24, control unit 6 determines that the predetermined time T or more has continued since time t23. Based on this determination result, control unit 6 outputs a pressure drop command the next time first bellows 13 is expanded (from time t27 to time t28), as will be described later.

[0091] At time t24 when the proximity sensor 31A is turned ON, the control unit 6 demagnetizes the solenoid 4b and magnetizes the solenoid 4a of the first solenoid valve 4. When the solenoid 4a of the first solenoid valve 4 is excited, as described above, the first bellows 13 starts contracting from the extended state just before the second bellows 14 enters the contracted state (in the middle of contraction).

[0092] After the first bellows 13 starts to contract, the control unit 6 determines that the second bellows 14 has contracted at time t25, a predetermined calculation time after time t24 when the proximity sensor 31A turned ON. The control unit 6 then demagnetizes the solenoid 5a of the second solenoid valve 5 and magnetizes the solenoid 5b. When the solenoid 5b of the second solenoid valve 5 is energized, the pressurized air generated by the air supply device 2 is supplied to the second suction-side air chamber 26B of the second drive unit 28, as described above.

[0093] At that time, since the control unit 6 determined that the pressure reduction determination made at the time t21 was positive (determined that the pressure reduction had continued for more than the predetermined time T since the time t20 when the proximity sensor 31B turned ON), it outputs a pressure reduction command to the second electro-pneumatic regulator 52 to reduce the air pressure of the pressurized air supplied to the second suction side air chamber 26B.

[0094] Specifically, the control unit 6 outputs a pressure reduction command to the second electropneumatic regulator 52 so that the air pressure of the pressurized air supplied to the second suction-side air chamber 26B becomes a value P23, which is lower than the previous value P21 (before time t21). Based on the pressure reduction command, the second electropneumatic regulator 52 adjusts the air pressure of the pressurized air supplied to the second suction-side air chamber 26B to the value P23. As a result, the second bellows 14 begins to expand from its contracted state. The expansion speed is slower than the expansion speed during the previous expansion operation of the second bellows 14.

[0095] Next, the control unit 6 determines whether the proximity sensor 31B has detected (ON) the expanded state of the second bellows 14 before the proximity sensor 29A has detected (ON) the mid-contraction state of the first bellows 13. Here, as described above, the expansion speed of the second bellows 14 slows and the expansion time of the second bellows 14 increases, so that the second bellows 14 reaches the expanded state at time t26 when the first bellows 13 reaches the mid-contraction state.

[0096] Therefore, before the first bellows 13 reaches the mid-contraction state, the proximity sensor 31B does not detect (is OFF) the expansion state of the second bellows 14, and the control unit 6 determines that the proximity sensor 31B has not turned ON. Based on this determination result, the control unit 6 does not perform a pressure reduction determination at time t26 when the first bellows 13 reaches the mid-contraction state, and therefore does not output a pressure reduction command the next time the second bellows 14 is expanded.

[0097] At time t26 when the proximity sensor 31B is turned ON, the control unit 6 demagnetizes the solenoid 5b and magnetizes the solenoid 5a of the second solenoid valve 5. When the solenoid 5a of the second solenoid valve 5 is excited, as described above, the second bellows 14 starts contracting from the extended state just before the first bellows 13 enters the contracted state (in the middle of contraction).

[0098] After the second bellows 14 starts to contract, the control unit 6 determines that the first bellows 13 has contracted at time t27, a predetermined calculation time after time t26 when the proximity sensor 29A turned ON. The control unit 6 then demagnetizes the solenoid 4a of the first solenoid valve 4 and magnetizes the solenoid 4b. When the solenoid 4b of the first solenoid valve 4 is energized, the 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, as described above.

[0099] At that time, since the control unit 6 determined that the pressure reduction determination made at time t24 was positive (determined that the pressure reduction had continued for more than the predetermined time T since time t23 when the proximity sensor 29B turned ON), it outputs a pressure reduction command to the first electro-pneumatic regulator 51 to reduce the air pressure of the pressurized air supplied to the first suction side air chamber 26A.

[0100] Specifically, the control unit 6 outputs a pressure reduction command to the first electropneumatic regulator 51 so that the air pressure of the pressurized air supplied to the first suction-side air chamber 26A becomes a value P13, which is lower than the previous value P11 (from time t22 to time t24). Based on the pressure reduction command, the first electropneumatic regulator 51 adjusts the air pressure of the pressurized air supplied to the first suction-side air chamber 26A to the value P13. As a result, the first bellows 13 begins to expand from its contracted state. The expansion speed is slower than the expansion speed during the previous expansion operation of the first bellows 13.

[0101] Next, the control unit 6 determines whether the proximity sensor 29B has detected (ON) the expanded state of the first bellows 13 before the proximity sensor 31A has detected (ON) the mid-contraction state of the second bellows 14. Here, as described above, the expansion speed of the first bellows 13 slows down and the expansion time of the first bellows 13 increases, so that the first bellows 13 reaches the expanded state at time t28 when the second bellows 14 reaches the mid-contraction state.

[0102] Therefore, before the second bellows 14 reaches the mid-contraction state, the proximity sensor 29B does not detect (is OFF) the expanded state of the first bellows 13, and the control unit 6 determines that the proximity sensor 29B has not turned ON. Based on this determination result, the control unit 6 does not perform a pressure reduction determination at time t28 when the second bellows 14 reaches the mid-contraction state, and therefore does not output a pressure reduction command the next time the first bellows 13 is expanded.

[0103] [Abnormality judgment] 1, if an abnormality such as a breakdown occurs in the first electropneumatic regulator 51 while the control unit 6 is performing drive control as described above, the first electropneumatic regulator 51 will maintain the air pressure adjusted immediately before the abnormality occurred. Therefore, even if the control unit 6 outputs a pressure increase command for pressure increase control or a pressure decrease command for pressure decrease control to the first electropneumatic regulator 51, the first electropneumatic regulator 51 will not be able to adjust the air pressure of the pressurized air. Therefore, the control unit 6 will continuously output pressure increase commands or pressure decrease commands to the first electropneumatic regulator 51.

[0104] Similarly, if an abnormality such as a breakdown occurs in the second electropneumatic regulator 52, the second electropneumatic regulator 52 will no longer be able to adjust the pressure of the pressurized air. For this reason, the control unit 6 will continuously output a pressure increase command or a pressure decrease command to the second electropneumatic regulator 52. The control unit 6 of this embodiment takes advantage of this continuous output to perform an abnormality determination to determine whether or not the first electropneumatic regulator 51 and the second electropneumatic regulator 52 are abnormal.

[0105] Specifically, the control unit 6 counts the number of times that the boost control has been performed consecutively for the first electropneumatic regulator 51 (second electropneumatic regulator 52). In this embodiment, the control unit 6 counts the number of times that the boost determination result is consecutively positive as the number of times that the boost control has been performed consecutively. The control unit 6 determines whether the counted number of times exceeds a predetermined number of times. If the determination result is positive, the control unit 6 determines that the first electropneumatic regulator 51 (second electropneumatic regulator 52) is abnormal.

[0106] Furthermore, the control unit 6 counts the number of times that the step-down control is continuously performed for the first electropneumatic regulator 51 (second electropneumatic regulator 52). In this embodiment, the control unit 6 counts the number of times that the step-down determination result is consecutively positive as the number of times that the step-down control is continuously performed. The control unit 6 determines whether the counted number of times exceeds a predetermined number. If the determination result is positive, the control unit 6 determines that the first electropneumatic regulator 51 (second electropneumatic regulator 52) is abnormal.

[0107] As described above, when either the number of consecutive positive determination results for the voltage increase determination or the number of consecutive positive determination results for the voltage decrease determination for the first electropneumatic regulator 51 (second electropneumatic regulator 52) exceeds a predetermined number, the control unit 6 determines that the first electropneumatic regulator 51 (second electropneumatic regulator 52) is abnormal. When the control unit 6 determines that the first electropneumatic regulator 51 or the second electropneumatic regulator 52 is abnormal, it switches the first solenoid valve 4 and the second solenoid valve 5 to stop the driving of the first drive unit 27 and the second drive unit 28.

[0108] The predetermined number of times may be set to the same value when the determination result of the voltage increase determination is consecutively positive and when the determination result of the voltage decrease determination is consecutively positive, or may be set to different values.

[0109] Fig. 7 is a flowchart showing an example of an abnormality determination performed by the control unit 6 during drive control. Below, the abnormality determination performed by the control unit 6 will be described with reference to Fig. 7. Note that the abnormality determination for the first electropneumatic regulator 51 and the abnormality determination for the second electropneumatic regulator 52 are performed in the same way, so here, the abnormality determination for the first electropneumatic regulator 51 will be described. First, the control unit 6 sets the values ​​of the count number N and the count number M to their initial values ​​of 0 (step ST1). The count number N is the number of times that the determination result of the voltage increase determination has been consecutively positive. The count number M is the number of times that the determination result of the voltage decrease determination has been consecutively positive.

[0110] Next, when the control unit 6 performs a boost determination for the first electro-pneumatic regulator 51 during drive control, if the determination result is positive ("Yes" in step ST2), it adds 1 to the count number N and resets the count number M to 0 (step ST3).

[0111] Next, the control unit 6 determines whether the count number N has exceeded a predetermined number (step ST4). If the count number N has not exceeded the predetermined number (if "No" in step ST4), the control unit 6 returns to step ST2. In this way, the processes from step ST2 to step ST4 are repeated, and the count number N gradually increases. Then, if the count number N exceeds the predetermined number (if "Yes" in step ST4), the control unit 6 determines that the first electro-pneumatic regulator 51 is abnormal (step ST5) and ends the process.

[0112] On the other hand, in step ST2, if the determination result of the voltage increase determination is negative ("No" in step ST2), the control unit 6 proceeds to step ST6. In step ST6, when the control unit 6 performs the voltage decrease determination of the first electropneumatic regulator 51, if the determination result is positive ("Yes" in step ST6), the control unit 6 resets the count number N to 0 and adds 1 to the count number M (step ST7). Furthermore, if the determination result of the voltage decrease determination is negative ("No" in step ST6), the control unit 6 returns to step ST1 without performing the process of step ST7. Note that, although the count number N is reset in step ST7 in this embodiment, the count number N may also be reset when the determination result in step ST2 is "No."

[0113] After performing the process of step ST7, the control unit 6 next determines whether or not the count number M has exceeded a predetermined number (step ST8). If the count number M has not exceeded the predetermined number (if "No" in step ST8), the control unit 6 returns to step ST2. In this way, the processes of steps ST2, ST6, ST7, and ST8 are repeated, so that the count number M gradually increases. Then, if the count number M exceeds the predetermined number (if "Yes" in step ST8), the control unit 6 determines that the first electro-pneumatic regulator 51 is abnormal (step ST5) and ends the process.

[0114] [Effects of this embodiment] According to the bellows pump device 1 of this embodiment, the control unit 6 counts the number of times that the pressure increase control of the first electropneumatic regulator 51 (second electropneumatic regulator 52) has been performed consecutively, and if the counted number exceeds a predetermined number, it determines that an abnormality has occurred in the first electropneumatic regulator 51 (second electropneumatic regulator 52). This makes it possible to determine that an abnormality has occurred in the first electropneumatic regulator 51 (second electropneumatic regulator 52) with an inexpensive configuration that does not use a pressure gauge or the like.

[0115] The control unit 6 counts the number of times that the pressure drop control of the first electropneumatic regulator 51 (second electropneumatic regulator 52) has been performed consecutively, and if the counted number exceeds a predetermined number, it determines that an abnormality has occurred in the first electropneumatic regulator 51 (second electropneumatic regulator 52). This makes it possible to determine that an abnormality has occurred in the first electropneumatic regulator 51 (second electropneumatic regulator 52) with an inexpensive configuration that does not use a pressure gauge or the like.

[0116] The control unit 6 determines that an abnormality has occurred in the first electropneumatic regulator 51 (second electropneumatic regulator 52) when either the number of times that voltage increase control has been performed continuously or the number of times that voltage decrease control has been performed continuously exceeds a predetermined number. Therefore, whether voltage increase control is performed continuously or voltage decrease control is performed continuously, it is possible to know that an abnormality has occurred in the first electropneumatic regulator 51 (second electropneumatic regulator 52).

[0117] The control unit 6 counts the number of consecutive affirmative determination results in the voltage boost determination as the number of consecutive times that voltage boost control has been performed. Therefore, the control unit 6 can determine that the number of consecutive times that voltage boost control has been performed exceeds a predetermined number before outputting a voltage boost command to the first electropneumatic regulator 51 (second electropneumatic regulator 52). This makes it possible to quickly determine that an abnormality has occurred in the first electropneumatic regulator 51 (second electropneumatic regulator 52).

[0118] The control unit 6 counts the number of consecutive affirmative determination results in the voltage reduction determination as the number of consecutive times that voltage reduction control has been performed. Therefore, the control unit 6 can determine that the number of consecutive times that voltage reduction control has been performed exceeds a predetermined number before outputting a voltage reduction command to the first electropneumatic regulator 51 (second electropneumatic regulator 52). This makes it possible to quickly determine that an abnormality has occurred in the first electropneumatic regulator 51 (second electropneumatic regulator 52).

[0119] [others] In the above embodiment, the first detection unit 29 is configured with proximity sensors 29A and 29B, but may be configured with a displacement sensor using laser light, etc. Similarly, the second detection unit 31 is configured with proximity sensors 31A and 31B, but may be configured with a displacement sensor using laser light, etc.

[0120] In the above embodiment, when the control unit 6 determines that the first electropneumatic regulator 51 or the second electropneumatic regulator 52 is abnormal, it stops the driving of the first drive unit 27 and the second drive unit 28. However, in addition to or instead of this, it may also be possible to cause the notification means to output a warning sound or the like.

[0121] In the above embodiment, the control unit 6 uses the number of times the determination result of the voltage step-up determination is consecutively positive as the number of times the voltage step-up control is consecutively performed, but it may also use the number of times the voltage step-up command is consecutively output. Similarly, the control unit 6 uses the number of times the determination result of the voltage step-down determination is consecutively positive as the number of times the voltage step-down control is consecutively performed, but it may also use the number of times the voltage step-down command is consecutively output.

[0122] 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 all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0123] 1 Bellows pump device 6 Control Unit 13 First Bellows (Bellows) 14 Second Bellows (Bellows) 21A First discharge side air chamber (discharge side fluid chamber) 21B Second discharge side air chamber (discharge side fluid chamber) 26A First suction side air chamber (suction side air chamber) 26B Second suction side air chamber (suction side air chamber) 27 First drive unit (drive unit) 28 Second drive unit (drive unit) 29 First detection unit (detection unit) 31 Second detection unit (detection unit) 51 First electropneumatic regulator (fluid pressure adjustment section) 52 Second electropneumatic regulator (fluid pressure adjustment section)

Claims

1. a pair of bellows that are independently expandable and contractible, and that draw in a transfer fluid when expanded and discharge the transfer fluid when contracted; a pair of drive units each having a suction-side fluid chamber and a discharge-side fluid chamber, each of which expands the bellows to a predetermined expanded state by supplying pressurized fluid to the suction-side fluid chamber and contracts the bellows to a predetermined contracted state by supplying pressurized fluid to the discharge-side fluid chamber; a pair of fluid pressure adjusting units that adjust the fluid pressure of the pressurized fluid supplied to the suction-side fluid chambers of the respective drive units; a pair of detectors for detecting the expansion and contraction states of the bellows; a control unit that controls the pair of drive units and the pair of fluid pressure adjustment units based on the detection signals of the pair of detection units, The control unit a drive control that controls the pair of drive units so that one of the pair of bellows contracts from the extended state before the other bellows reaches the contracted state; when the one bellows has contracted to a mid-contraction state immediately before reaching the contracted state, a pressure increase determination is performed to determine whether the other bellows is in the middle of expansion, and if the determination result of the pressure increase determination is affirmative, a pressure increase control is performed to output a pressure increase command to the fluid pressure adjustment unit corresponding to the drive unit that expands the other bellows so as to increase the fluid pressure when the other bellows is next expanded, The bellows pump device counts the number of times the pressure increase control is performed consecutively, and determines that the fluid pressure adjustment unit is abnormal if the counted number exceeds a predetermined number.

2. a pair of bellows that are independently expandable and contractible, and that draw in a transfer fluid when expanded and discharge the transfer fluid when contracted; a pair of drive units each having a suction-side fluid chamber and a discharge-side fluid chamber, each of which expands the bellows to a predetermined expanded state by supplying pressurized fluid to the suction-side fluid chamber and contracts the bellows to a predetermined contracted state by supplying pressurized fluid to the discharge-side fluid chamber; a pair of fluid pressure adjusting units that adjust the fluid pressure of the pressurized fluid supplied to the suction-side fluid chambers of the respective drive units; a pair of detectors for detecting the expansion and contraction states of the bellows; a control unit that controls the pair of drive units and the pair of fluid pressure adjustment units based on the detection signals of the pair of detection units, The control unit a drive control that controls the pair of drive units so that one of the pair of bellows contracts from the extended state before the other bellows reaches the contracted state; when the one bellows has contracted to a mid-contraction state immediately before reaching the contracted state, a pressure reduction determination is performed to determine whether the other bellows has continued to be in the expanded state for a predetermined time or more, and if the result of the pressure reduction determination is affirmative, a pressure reduction control is performed to output a pressure reduction command to the fluid pressure adjustment unit corresponding to the drive unit that extends the other bellows so as to reduce the fluid pressure when the other bellows is next expanded, The bellows pump device counts the number of times the pressure reduction control is performed consecutively, and determines that the fluid pressure adjustment unit is abnormal if the counted number exceeds a predetermined number.

3. The control unit When the one bellows has contracted to the intermediate contraction state, a pressure reduction determination is performed to determine whether the other bellows has continued to be in the expanded state for a predetermined time or more, and if the result of the pressure reduction determination is affirmative, a pressure reduction control is further performed to output a pressure reduction command to the fluid pressure adjustment unit corresponding to the drive unit that extends the other bellows so as to reduce the fluid pressure when the other bellows is next expanded, 2. The bellows pump device according to claim 1, wherein the number of times the pressure-lowering control has been performed consecutively is counted, and when either the number of times the pressure-increasing control has been performed consecutively or the number of times the pressure-lowering control has been performed consecutively exceeds a predetermined number, it is determined that the fluid pressure adjusting unit is abnormal.

4. 4. The bellows pump device according to claim 1, wherein the control unit counts the number of times the pressure increase determination result is consecutively positive as the number of times the pressure increase control has been consecutively performed.

5. 4. The bellows pump device according to claim 2, wherein the control unit counts the number of consecutive positive determination results of the pressure reduction determination as the number of consecutive times the pressure reduction control has been performed.

Images