Fluid discharge system

Abstract

[Problem] The objective is to provide a fluid discharge system capable of reducing pressure in a piping system formed from a supply path or the like to an appropriate level while in a state of not discharging a fluid. [Solution] A fluid discharge system (10) comprises: a discharge device (30); a supply pump (20); a supply path (40) connecting the discharge device (30) and the pump so as to allow a fluid to pass therebetween; a pressure regulating tank (50), partway along the supply path (40), that allows the fluid to flow in and out thereof; and a control device (200). The control unit (200) carries out control to regulate the flow of fluid in and out of the pressure regulating tank (50) to allow for execution of a low pressure maintaining mode that maintains the internal pressure (P) of the supply path (40) during a stop period when a discharge operation is stopped at a lower pressure than a standard range of the internal pressure (P) of the supply path (40) during a discharge period when the discharge operation is performed.

Description

Fluid Dispensing System

[0001] The present invention relates to a fluid dispensing system that supplies a fluid to a dispensing device and dispenses it.

[0002] A conventional fluid dispensing system is disclosed in Patent Document 1 below. This fluid dispensing system includes a dispensing device that dispenses a fluid, a pump that can supply the fluid stored in a storage section toward the dispensing device, a supply path that connects the dispensing device and the pump so that the fluid can pass through, and a buffer tank located midway through the supply path. The fluid dispensing system of Patent Document 1 can be operated in various modes: a tank accumulation mode in which the fluid is accumulated in the buffer tank, a pump supply mode in which the fluid is supplied from the pump to the dispensing device, a tank supply mode in which the fluid is discharged from the buffer tank and supplied to the dispensing device, and a combined supply mode in which the fluid is supplied from both the pump and the buffer tank to the dispensing device.

[0003] Japanese Patent Application Laid-Open No. 2021-178314

[0004] The present inventors have thoroughly studied the fluid dispensing system disclosed in Patent Document 1 and have found that there is room for further improvement. Specifically, when a product is produced using a fluid dispensing system such as that described in Patent Document 1, the fluid may be left in the piping after one day's production is completed so that production can begin immediately the next day. In this case, because the entire piping system is highly sealed, the fluid is maintained at a high supply pressure within the piping system for a long period of time until production begins the next day. However, depending on the type of fluid being handled, exposure to a high-pressure environment for a long period of time can cause deterioration, or the high permeability can cause the fluid to gradually permeate gaps in the piping connections due to internal pressure, resulting in leakage to the outside.

[0005] Therefore, it is common practice to provide a drain port in a piping system consisting of a supply path, etc., and when the discharge device has finished discharging the fluid and is to be stopped for an extended period of time, to release the drain port to the atmosphere and discharge the fluid using internal pressure, thereby reducing the pressure in the piping. In this case, the fluid discharged from the drain port becomes waste liquid, which can cause the problem of high loss costs if the fluid is expensive.

[0006] In addition, in order to improve the efficiency of the discharge process of fluids, a method is sometimes used in which a vacuum pump is connected to the drain port and the pressure in the piping is reduced by forcibly sucking the fluid. However, if the pressure is reduced to a negative pressure below atmospheric pressure, air will be drawn into the piping, and there is a risk that air will get mixed into the fluid after the next discharge starts, causing a manufacturing defect (so-called air entrapment).

[0007] Therefore, it is desirable that this type of fluid dispensing system be capable of controlling the pressure in the piping system to reduce and maintain an appropriate level that does not cause the problems described above when the dispensing device is stopped from dispensing fluid.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a fluid dispensing system that can control the pressure inside a piping system including supply paths, etc. to be reduced to an appropriate level and maintained when no fluid is being dispensed.

[0009] (1) The fluid discharge system of the present invention comprises a discharge device that performs a discharge operation to discharge a fluid, a supply pump that can supply the fluid toward the discharge device, a supply path that connects the discharge device and the pump so that the fluid can pass through, a pressure adjustment tank that can allow the fluid to flow in and out of the supply path midway, and a control device that controls the internal pressure of the supply path by adjusting the flow of fluid in and out of the pressure adjustment tank, and by controlling the flow of fluid in and out of the pressure adjustment tank using the control device, a low pressure maintenance mode can be implemented in which the internal pressure of the supply path during a stop period in which the discharge operation is stopped is maintained at a pressure lower than the standard range of the internal pressure of the supply path during a discharge period in which the discharge operation is performed.

[0010] The fluid dispensing system of the present invention includes a pressure adjustment tank provided midway through a supply line connecting a dispensing device and a supply pump, allowing the inflow and outflow of fluid. The fluid dispensing system of the present invention is capable of controlling the internal pressure of the supply line by regulating the inflow and outflow of fluid in the pressure adjustment tank under the control of a control device. Furthermore, the fluid dispensing system of the present invention can control the internal pressure of the supply line to be lower than the standard range of internal pressure of the supply line during a dispensing period by executing control in a low-pressure maintenance mode and regulating the inflow and outflow of fluid in the pressure adjustment tank. Therefore, the fluid dispensing system of the present invention can reduce the pressure in the piping system, including the supply line, to an appropriate level when no fluid is being dispensed.

[0011] (2) In the fluid discharge system of the present invention, the control device, in the low pressure maintenance mode, controls the inflow and outflow of fluid in the pressure adjustment tank so that the internal pressure of the supply line is maintained within a low-pressure maintenance pressure range that is lower than the standard range, and, on the condition that the internal pressure of the supply line exceeds the upper threshold of the low-pressure maintenance pressure range or is expected to exceed the upper threshold, reduces the internal pressure of the supply line by introducing fluid into the pressure adjustment tank, and, on the condition that the internal pressure of the supply line is below the lower threshold of the low-pressure maintenance pressure range or is expected to fall below the lower threshold, discharges the fluid in the pressure adjustment tank into the supply line to pressurize the supply line.

[0012] The fluid discharge system of the present invention, by adopting the configuration according to (2) above, can prevent the internal pressure of the supply passage from deviating from the range of the low-pressure maintenance pressure region and becoming high or low in the low-pressure maintenance mode. As a result, the fluid discharge system of the present invention can reduce the pressure inside the piping system including the supply passage etc. to an appropriate level while stabilizing the pressure within the low-pressure maintenance pressure region when no fluid is being discharged.

[0013] Here, when the internal pressure of the supply passage becomes equal to or lower than atmospheric pressure in the above-mentioned low-pressure maintenance mode, gas such as air may be mixed into the supply passage, resulting in a so-called air entrapment state. When air entrapment occurs in a fluid dispensing system, there is a concern that problems such as interruptions in the fluid during the dispensing operation may occur.

[0014] (3) Based on this knowledge, in the fluid discharge system of the present invention, the control device may be configured to control the pressure in the supply path to be maintained higher than atmospheric pressure in the low pressure maintenance mode.

[0015] By adopting the configuration according to (3) above, the fluid dispensing system of the present invention can prevent air from being trapped in the supply passage when the low pressure maintenance mode is executed.

[0016] (4) In the fluid dispensing system of the present invention, the control device may be capable of executing control in a pressure recovery mode in which the fluid in the pressure adjustment tank is discharged into the supply path to pressurize the supply path before the dispensing device, which has stopped dispensing operation, resumes dispensing operation.

[0017] The fluid discharge system of the present invention is configured to have a pressure recovery mode as described above in (4), thereby improving discharge responsiveness when the discharge operation is restarted.

[0018] Here, for example, when a slurry liquid in which a filler is dispersed in liquid silicone is exposed to a high-pressure atmosphere for a long period of time, a phenomenon called caking occurs. When the caking phenomenon occurs, the liquid silicone and the filler separate, causing the filler to aggregate in some parts of the liquid, which may have a negative impact on discharge and application. Thus, when handling a slurry liquid as a fluid, it is desirable to prevent it from being exposed to a high-pressure atmosphere for a long period of time.

[0019] (5) Based on the above findings, the fluid discharge system of the present invention can be suitably used when supplying and discharging a slurry liquid as the fluid.

[0020] As described above, the fluid dispensing system of the present invention can control the internal pressure of the supply path to be lower than the standard range of the internal pressure of the supply path during the dispensing period when the dispensing device stops dispensing. Therefore, even when the fluid dispensing system of the present invention is used to supply and dispense a slurry liquid as the fluid, it can prevent the occurrence of phenomena such as the caking phenomenon described above that have an adverse effect on dispensing and application.

[0021] (6) In the fluid discharge system of the present invention, the pressure adjustment tank may be capable of supplying fluid to the discharge device in place of the supply pump or in combination with the supply pump while the discharge device is in operation.

[0022] By adopting the configuration according to (6) above, the fluid discharge system of the present invention can continue to discharge without interruption even if the supply pump stops during operation of the discharge device by supplying the fluid from the pressure adjustment tank to the discharge device instead. Furthermore, by supplying the fluid to the discharge device from the pressure adjustment tank and the supply pump in combination, a stable supply of fluid to the discharge device can be achieved.

[0023] When the fluid discharge system of the present invention is configured as described above in (6), the operation of the pressure adjustment tank to supply fluid to the discharge device in place of the supply pump or in combination with the supply pump while the discharge device is in operation (alternative supply) may be performed, for example, with one or all of the starting conditions being that the supply pump is stopped while the discharge device is in operation.

[0024] (7) In the fluid discharge system of the present invention, the pressure adjustment tank is provided with a content volume grasping unit that grasps the content volume of the fluid in the pressure adjustment tank, and the control device, when accumulating fluid in the pressure adjustment tank for the alternative supply, grasps the content volume using the content volume grasping unit and controls the accumulated amount of fluid so as to ensure free capacity for the inflow of fluid to reduce the internal pressure of the supply path in the low pressure maintenance mode.

[0025] By adopting the configuration according to (7) above, the fluid dispensing system of the present invention can store fluid in the internal pressure adjustment tank in preparation for alternative supply while ensuring that the internal pressure adjustment tank has sufficient free capacity to operate in the low pressure maintenance mode. This allows the fluid dispensing system of the present invention to operate in both the low pressure maintenance mode and alternative supply or combined supply using the same pressure adjustment tank.

[0026] According to the present invention, it is possible to provide a fluid dispensing system that can reduce the pressure in a piping system including supply paths and the like to an appropriate level when no fluid is being dispensed.

[0027] FIG. 1 is a schematic diagram showing a fluid discharging system according to a first embodiment and a third embodiment of the present invention. FIG. 2 is a cross-sectional view showing an example of a discharge device used in the fluid discharging system of FIG. 1. FIG. 3 is a cross-sectional view showing an example of a buffer tank used in the fluid discharging system of FIG. 1. FIG. 4 is a flowchart showing the overall operation of the fluid discharging system according to the first embodiment and a second embodiment. FIG. 5 is a timing chart showing the overall operation of the fluid discharging system according to the first embodiment. FIG. 6 is a schematic diagram showing a fluid discharging system according to a second embodiment of the present invention. FIG. 7 is a flowchart showing normal operation of the fluid discharging system according to the second embodiment. FIG. 8 is a timing chart showing the overall operation of the fluid discharging system according to the second embodiment. FIG. 9 is an explanatory diagram for explaining a basic upper limit accumulation threshold, an allowable upper limit of accumulation amount fluctuation, and an allowable lower limit of accumulation amount fluctuation that are set in the fluid discharging system according to the third embodiment. FIG. 11 is a flowchart showing the flow of operation in a pump supply mode performed in the fluid discharging system according to the third embodiment.

[0028] First Embodiment A fluid dispensing system 10 according to a first embodiment of the present invention will be described in detail below with reference to the drawings. In the following description, the configuration of the fluid dispensing system 10 will be described first, and then the operation of the fluid dispensing system 10 will be described.

[0029] <<Configuration of the Fluid Dispensing System 10>> The fluid dispensing system 10 is used to supply and dispense a fluid. The fluid dispensing system 10 can handle a variety of fluids, but is particularly suited to handling, for example, a slurry liquid in which a filler is dispersed in liquid silicone. As shown in FIG. 1 , the fluid dispensing system 10 is configured to connect a supply pump 20 and a dispensing device 30 via a supply path 40. The fluid dispensing system 10 is configured to include a pressure adjustment tank 50 disposed midway through the supply path 40. The fluid dispensing system 10 can supply and dispense a fluid to the dispensing device 30 through this piping system. The fluid dispensing system 10 also includes a remaining amount monitoring unit 90 for monitoring the remaining amount of fluid in the dispensing device 30. The fluid dispensing system 10 also includes a control device 200 for controlling the operation of the supply pump 20, the dispensing device 30, and the pressure adjustment tank 50. The fluid discharge system 10 can discharge the fluid supplied by the supply pump 20 and the pressure adjustment tank 50 toward the workpiece in the discharge device 30.

[0030] The supply pump 20 is a device for pumping up and pressure-feeding a fluid from a storage section 22 in which the fluid is stored. The supply pump 20 is connected to a supply path 40 by piping. Therefore, the fluid pumped up from the storage section by the supply pump 20 can be pressure-feed to the discharge device 30 side via the supply path 40.

[0031] The discharge device 30 is configured as a rotary positive displacement pump. In this embodiment, the discharge device 30 is configured as a so-called uniaxial eccentric screw pump. As shown in FIG. 2 , the discharge device 30 is configured such that a rotor 102, a stator 104, a power transmission mechanism 106, and the like are housed inside a casing 100. The casing 100 is a metallic, cylindrical member, and is provided with a first opening 110 at one longitudinal end. In addition, a second opening 112 is provided on the outer periphery of the casing 100. The second opening 112 communicates with the internal space of the casing 100 at an intermediate portion 114 located in the longitudinal intermediate portion of the casing 100.

[0032] The first opening 110 and the second opening 112 are portions that function as a suction port and a discharge port, respectively, of the uniaxial eccentric screw pump that constitutes the discharge device 30. In the discharge device 30, the first opening 110 can function as a discharge port and the second opening 112 as a suction port by rotating the rotor 102 in the forward direction. In addition, the first opening 110 can function as a suction port and the second opening 112 as a discharge port by rotating the rotor 102 in the reverse direction.

[0033] The stator 104 is a member having a generally cylindrical external shape and made of an elastic material such as rubber, or a resin. The inner peripheral wall 116 of the stator 104 has an n-thread, single-stage or multi-stage female thread shape. In this embodiment, the stator 104 has a two-thread, multi-stage female thread shape. Furthermore, the through-hole 118 of the stator 104 is formed so that its cross-sectional shape (opening shape) is generally oval when viewed in cross section at any position in the longitudinal direction of the stator 104.

[0034] The rotor 102 is a metal shaft having an n-1 thread, single-stage or multi-stage male screw. In this embodiment, the rotor 102 has a single-stage eccentric male screw. The rotor 102 is formed so that its cross-sectional shape is a substantially perfect circle when viewed in cross section at any position in the longitudinal direction. The rotor 102 is inserted into a through-hole 118 formed in the stator 104 described above, and is capable of free eccentric rotation within the through-hole 118.

[0035] When the rotor 102 is inserted into the stator 104, the outer peripheral wall 120 of the rotor 102 and the inner peripheral wall 116 of the stator 104 come into close contact at their tangents, and a fluid transport path 122 (cavity) is formed between the inner peripheral wall 116 of the stator 104 and the outer peripheral wall 120 of the rotor 102. The fluid transport path 122 extends spirally in the longitudinal direction of the stator 104 and the rotor 102.

[0036] When the rotor 102 is rotated within the through-hole 118 of the stator 104, the fluid transport path 122 advances in the longitudinal direction of the stator 104 while rotating within the stator 104. Therefore, when the rotor 102 is rotated, fluid is sucked into the fluid transport path 122 from one end side of the stator 104, and this fluid is transported toward the other end side of the stator 104 while being confined within the fluid transport path 122, and can be discharged from the other end side of the stator 104. Specifically, when the rotor 102 is rotated in the forward direction, an operation of sucking a fluid through the second opening 112 and discharging it from the first opening 110 (discharge operation) can be performed. Furthermore, when the rotor 102 is rotated in the reverse direction, an operation of sucking a fluid in the opposite direction to the discharge operation, i.e., from the first opening 110 side toward the second opening 112 side (pull-back operation) can be performed.

[0037] The power transmission mechanism 106 transmits power from the driver 124 to the rotor 102. The power transmission mechanism 106 includes a power transmission unit 126 and an eccentric rotation unit 128. The power transmission unit 126 is provided at one longitudinal end of the casing 100. The eccentric rotation unit 128 is provided in the intermediate portion 114. The eccentric rotation unit 128 connects the power transmission unit 126 and the rotor 102 so that power can be transmitted between them. The eccentric rotation unit 128 includes a connecting shaft 130 formed of a conventionally known coupling rod, screw rod, or the like. Therefore, the eccentric rotation unit 128 can transmit rotational power generated by operating the driver 124 to the rotor 102, causing the rotor 102 to rotate eccentrically.

[0038] The supply path 40 is a flow path that connects the supply pump 20 and the discharge device 30 so that the fluid can pass through. A pressure adjustment tank 50, which will be described in detail later, is provided midway through the supply path 40. Specifically, the supply path 40 has a primary supply path 42 that connects the primary side of the pressure adjustment tank 50 (the upstream side of the supply path 40 in the direction of the fluid flow) and the supply pump 20, and a secondary supply path 44 that connects the secondary side of the pressure adjustment tank 50 (the downstream side of the supply path 40 in the direction of the fluid flow) and the discharge device 30.

[0039] A sensor 92 constituting a remaining amount monitoring unit 90 (described in detail below) and a valve 48 are provided midway through the supply path 40. The sensor 92 may be, for example, a pressure gauge or a flow meter, capable of detecting the state of the fluid in the supply path 40. In this embodiment, the sensor 92 is a pressure gauge. The sensor 92 is disposed in the supply path 40 between the discharge device 30 and the pressure adjustment tank 50. The valve 48 is also disposed in the supply path 40 between the supply pump 20 and the pressure adjustment tank 50. The valve 48 is capable of restricting (blocking, in this embodiment) the flow of the fluid from the supply pump 20 to the discharge device 30. The valve 48 may be configured as a so-called two-way valve, a check valve, or the like.

[0040] The pressure adjustment tank 50 is disposed midway along the above-described supply path 40. The pressure adjustment tank 50 adjusts the internal pressure P of the supply path 40 by allowing a fluid to flow in and out midway along the supply path 40. As shown in FIG. 3 , the pressure adjustment tank 50 has a tank portion 52, a volume fluctuation mechanism 54, and an internal volume monitoring portion 55.

[0041] The tank portion 52 is capable of allowing a fluid to flow in and out of the supply path 40. In this embodiment, the tank portion 52 has a connection portion 56 provided at one end of a tubular (in this embodiment, substantially cylindrical) tank main body portion 52a extending in a predetermined axial direction, and a communicating space 58 and a non-communicating space 60 provided inside the tank main body portion 52a.

[0042] The connection portion 56 is provided on one axial end side of the tank main body 52a that constitutes the tank portion 52. The connection portion 56 is a portion that is connected to the supply path 40. The connection portion 56 has a flow path 56a that extends in a direction (in the radial direction in this embodiment) that intersects the axial direction of the tank portion 52. The connection portion 56 has connection ports 56b, 56c at both ends of the flow path 56a. The connection ports 56b, 56c open at the periphery of the tank portion 52 and are connectable to the piping that constitutes the supply path 40. The connection portion 56 also has a communication hole 56d in the radial middle portion of the tank portion 52. The tank portion 52 is in communication with the flow path 56a and the internal space (communication space 58) of the tank main body 52a via the communication hole 56d.

[0043] The communication space 58 is a space provided on the side of the tank part 52 where the connection part 56 is provided. The communication space 58 is formed to communicate with the supply path 40 via the connection part 56 described above. Therefore, the tank part 52 is capable of sucking and discharging fluid into and from the communication space 58 between the tank part 52 and the supply path 40 connected to the connection part 56.

[0044] The non-communicating space 60 is a space that is not in communication with the supply path 40. The non-communicating space 60 is a space that is adjacent to the communicating space 58 in the axial direction of the tank portion 52, on the opposite side of the connecting portion 56 from the communicating space 58. The non-communicating space 60 is separated from the communicating space 58 by a piston portion 62 (partition portion) of the volume fluctuation mechanism 54, which will be described in detail later. The volume fluctuation mechanism 54 is connected to an end of the non-communicating space 60. As a result, the non-communicating space 60 is in communication with a casing 68 that forms a drive portion 64 of the volume fluctuation mechanism 54.

[0045] The volume variation mechanism 54 is an operating mechanism that varies the volume of the communicating space 58 in the tank portion 52. The volume variation mechanism 54 has a piston portion 62 and a drive portion 64, and the drive portion 64 can move the piston portion 62 in the axial direction of the tank portion 52 inside the tank portion 52. Therefore, the volume variation mechanism 54 can vary the volume (volume ratio) of the communicating space 58 and the non-communicating space 60 inside the tank portion 52 by changing the position of the piston portion 62 with the drive portion 64.

[0046] The piston portion 62 separates the interior of the tank portion 52 into a communicating space 58 and a non-communicating space 60. In this embodiment, the piston portion 62 is a piston. The outer diameter of the piston that constitutes the piston portion 62 is approximately the same as the inner diameter of the tank portion 52. A seal member 62a is attached to the outer periphery of the piston portion 62. As a result, the piston portion 62 separates the internal space of the tank main body portion 52a into a communicating space 58 and a non-communicating space 60 while sealing to prevent leakage of liquids, including fluids, and gases.

[0047] The drive unit 64 is for moving the piston unit 62 in the axial direction inside the tank main body 52a. The drive unit 64 has a rod unit 66 connected to the piston unit 62 and a drive device (not shown) that moves the rod unit 66 in the axial direction. The drive unit 64 can move the piston unit 62 in the axial direction inside the tank main body 52a by moving the rod unit 66 in the axial direction using the drive device.

[0048] The content volume monitoring unit 55 monitors the content volume (remaining volume) of the fluid inside the pressure adjustment tank 50. The content volume monitoring unit 55 may be provided with a sensor capable of measuring the volume of the communication space 58 in the tank unit 52, a linear encoder that detects the current position of the piston unit 62, or other sensors, and may determine the amount of fluid stored (content volume) in the pressure adjustment tank 50 based on output values ​​from these sensors, or may be capable of detecting or deriving the amount of fluid flowing into and out of the pressure adjustment tank 50 and determining the amount of fluid stored in the pressure adjustment tank 50 based on the amount of inflow and outflow. The content volume monitoring unit 55 may be configured to detect the amount of fluid stored in multiple stages, for example, based on the output of a sensor provided at the upper or lower limit position of the pressure adjustment tank 50, or may be configured to continuously detect the amount of fluid stored in the pressure adjustment tank 50.

[0049] By utilizing the above-described configuration, the pressure adjustment tank 50 can achieve three states: a pressurized state, a depressurized state, and a holding state. Each of these states can be achieved by controlling the movement of the piston 62 inside the tank 52 using the drive unit 64 constituting the volume fluctuation mechanism 54.

[0050] Specifically, the pressurized state is a state in which a pressurizing force is exerted on the fluid. The pressurized state can be achieved by using the volume fluctuation mechanism 54 to reduce the volume of the communication space 58 in the tank portion 52 that communicates with the supply path 40.

[0051] The reduced pressure state is a state in which a decompression force is exerted on the fluid. The reduced pressure state can be achieved by increasing the volume of the communication space 58 that communicates with the supply path 40 within the tank portion 52 using the volume fluctuation mechanism 54.

[0052] The holding state is a state in which neither pressure nor vacuum is applied to the fluid, and can be achieved by stopping the volume fluctuation mechanism 54 from increasing or decreasing the volume of the communication space 58.

[0053] The control device 200 is for controlling the operation of the fluid discharge system 10. The control device 200 controls the operation of the supply pump 20, the discharge device 30, the pressure adjustment tank 50, etc. The control device 200 can control the internal pressure P of the supply path 40 by adjusting the flow of fluid in and out of the pressure adjustment tank 50.

[0054] <Operation of the fluid dispensing system 10> The fluid dispensing system 10 can be operated in one or more operation modes under the control of the control device 200. In this embodiment, the fluid dispensing system 10 can be operated in two operation modes: (1) a low-pressure maintenance mode and (2) a pressure recovery mode, in addition to an operation for dispensing a fluid (normal operation). Below, the normal operation performed by the fluid dispensing system 10 and the operation in the two operation modes described above performed by the fluid dispensing system 10 will be described. Furthermore, after describing the operation in each operation mode, the overall operation of the fluid dispensing system 10, which is realized by sequentially performing the operation in each operation mode, will be described.

[0055] [Normal Operation] Normal operation is an operation in which the supply pump 20 sucks up the fluid from the storage section 22 and sends the fluid toward the discharge device 30 via the supply path 40, while the discharge device 30 discharges the fluid. In normal operation, as the discharge device 30 performs the discharge operation, the supply pump 20 is operated to supply the fluid consumed by the discharge to the discharge device 30 via the supply path 40.

[0056] Here, during normal operation, the control device 200 operates the supply pump 20 with the goal of maintaining the internal pressure P of the supply path 40 within a predetermined standard supply pressure range. Specifically, when the discharge device 30 discharges a fluid, the internal pressure P of the supply path 40 decreases. The control device 200 starts pumping the fluid to the discharge device 30 using the supply pump 20 on the condition that the internal pressure P of the supply path 40 detected by the remaining amount determination unit 90 (sensor 92) falls below a supply pressure lower limit threshold SPL, which is the lower limit of the standard supply pressure range. This allows the fluid discharge system 10 to operate the supply pump 20 to supply the fluid to the discharge device 30 via the supply path 40 in order to prevent a shortage of fluid to the discharge device 30. Meanwhile, when the supply pump 20 pumps the fluid, the internal pressure P of the supply path 40 increases. The control device 200 controls the supply pump 20 to stop pumping the fluid to the discharge device 30 on the condition that the internal pressure P of the supply path 40 exceeds the supply pressure upper threshold SPH, which is the upper limit of the standard supply pressure range. This allows the fluid discharge system 10 to stop the operation of the supply pump 20 at an appropriate timing to prevent the supply pump 20 from oversupplying the fluid to the discharge device 30. By operating the supply pump 20 in accordance with the internal pressure P of the supply path 40 in this way, the fluid discharge system 10 maintains the internal pressure P of the supply path 40 within the range of the standard supply pressure range (the range that the internal pressure P of the supply path 40 should be in to prevent an undersupply or oversupply of the fluid to the discharge device 30), while continuing to discharge the fluid from the discharge device 30 and performing normal operation.

[0057] [(1) Low-Pressure Maintenance Mode] The low-pressure maintenance mode is an operating mode in which the internal pressure P of the supply path 40 during a stop period in which the discharge operation of the discharge device 30 is stopped is maintained at a pressure range lower than the standard range (standard supply pressure range) of the internal pressure P of the supply path 40 during a discharge period in which the discharge operation is performed. In the low-pressure maintenance mode, the control device 200 opens the valve 48 provided in the supply path 40 between the pressure adjustment tank 50 and the supply pump 20. The low-pressure maintenance mode is realized by the control device 200 controlling the flow of fluid into and out of the pressure adjustment tank 50 while the supply pump 20 and the discharge device 30 are stopped. The low-pressure maintenance mode is realized by controlling the flow of fluid into and out of the pressure adjustment tank 50 so that the internal pressure P of the supply path 40 is maintained at a pressure higher than atmospheric pressure within a low-pressure maintenance pressure range that is lower than the standard supply pressure range.

[0058] Specifically, the control device 200 controls the pressure adjustment tank 50 to a reduced pressure state on the condition that the internal pressure P of the supply path 40 exceeds the upper threshold of the low-pressure maintenance pressure range (low-pressure control upper threshold pressure LPH) or is expected to exceed the low-pressure control upper threshold pressure LPH. As a result, the fluid is introduced from the supply path 40 into the pressure adjustment tank 50, and the internal pressure P of the supply path 40 is reduced.

[0059] On the other hand, the control device 200 controls the pressure adjustment tank 50 to be pressurized on the condition that the internal pressure P of the supply path 40 is below the lower limit threshold of the low-pressure maintenance pressure range (low-pressure control lower limit threshold LPL) or is expected to fall below the low-pressure control lower limit threshold LPL. As a result, the fluid in the pressure adjustment tank 50 is discharged into the supply path 40, and the inside of the supply path 40 is pressurized.

[0060] Furthermore, when the internal pressure P of the supply path 40 is in the low-pressure maintenance pressure range (LPL≦P≦LPH), the pressure adjustment tank 50 is placed in a holding state. This stops the flow of fluid in and out of the pressure adjustment tank 50 and the supply path 40, and the internal pressure P of the supply path 40 is maintained within the low-pressure maintenance pressure range. In this way, the fluid discharge system 10 controls the operation of the pressure adjustment tank 50 using the control device 200, and adjusts the flow of fluid in and out of the pressure adjustment tank 50, thereby achieving operation in the low-pressure maintenance mode.

[0061] (2) Pressure Recovery Mode The pressure recovery mode is an operating mode that is executed by the discharge device 30, which has stopped discharging, before the discharge device 30 resumes discharging, to return the internal pressure P of the supply path 40 toward the standard supply pressure range. The pressure recovery mode can increase the internal pressure P of the supply path 40 to a pressure within the standard supply pressure range, to a pressure exceeding the standard supply pressure range, or to a pressure lower than the pressure associated with the standard supply pressure range but that is expected to return to the standard supply pressure range upon resumption of discharging. For example, the pressure recovery mode can increase the internal pressure P to a pressure lower than the lower limit threshold of the standard supply pressure range (supply pressure lower limit threshold SPL) taking into account the supply pressure that will be applied by the supply pump 20 upon resumption of discharging.

[0062] The pressure recovery mode is realized by controlling the flow of fluid in and out of the pressure adjustment tank 50 when the internal pressure P of the supply path 40 drops to a pressure below the supply pressure lower threshold SPL of the standard supply pressure range due to, for example, operation in the low pressure maintenance mode following the cessation of the discharge operation. Specifically, the control device 200 pressurizes the pressure adjustment tank 50 when the internal pressure P of the supply path 40 is below the supply pressure lower threshold SPL of the standard supply pressure range. This causes the fluid in the pressure adjustment tank 50 to be discharged into the supply path 40, thereby increasing the internal pressure P of the supply path 40. At this time, the control device 200 increases the internal pressure P of the supply path 40 within a range in which the internal pressure P of the supply path 40 does not exceed the upper threshold (supply pressure upper threshold SPH) of the standard supply pressure range. In this way, when the internal pressure P of the supply path 40 has increased to a pressure within the standard supply pressure range, or has increased to a pressure that is expected to return to the standard supply pressure range as the discharge operation resumes, the control device 200 sets the pressure adjustment tank 50 to a holding state. This allows the discharge device 30 to wait in a state where the internal pressure P in the supply path 40 has increased to the standard supply pressure range or close to the standard supply pressure range, in preparation for the discharge operation being resumed.

[0063] Furthermore, the pressure recovery mode can stop the discharge of fluid from the pressure adjustment tank 50 on the condition that the internal pressure P returns to a pressure specified based on the standard supply pressure range, but it can also be set to continue until a predetermined amount or all of the fluid stored inside the pressure adjustment tank 50 is discharged to the supply path 40. In other words, the pressure recovery mode can be executed by a method of controlling the discharge of fluid from the pressure adjustment tank 50 to the supply path 40 using the internal pressure P as a judgment criterion, or a method of controlling the discharge amount of fluid from the pressure adjustment tank 50 to the supply path 40 as a criterion.

[0064] [Overall Operation of Fluid Dispensing System 10] The overall operation of the fluid dispensing system 10, including the operations in the low-pressure maintenance mode and the pressure recovery mode, will be described in detail below with reference to the flowchart in Fig. 4 and the timing chart in Fig. 5. Note that, since this embodiment assumes a highly viscous liquid as the fluid, even if control is executed to switch the internal pressure P's up-and-down movement immediately after the internal pressure P exceeds each threshold value described in detail below, there will be a slight time lag before the actual tendency of the internal pressure P's up-and-down movement changes. Therefore, each threshold value is set taking into account the fluctuation during the time lag.

[0065] (Step 1-1) First, in step 1-1, the fluid dispensing system 10 operates (normally) to suck up fluid from the reservoir 22 using the supply pump 20 and send the fluid toward the discharge device 30 via the supply path 40, while the discharge device 30 discharges the fluid. At this time, the discharge device 30 performs a discharge operation, and the fluid consumed by the discharge is supplied via the supply path 40. As a result, the internal pressure P of the supply path 40 decreases. To prevent a shortage of fluid to the discharge device 30, the supply pump 20 begins pumping the fluid to the discharge device 30 on the condition that the internal pressure P of the supply path 40 detected by the remaining amount grasping unit 90 (sensor 92) falls below the supply pressure lower limit threshold SPL. As a result, the internal pressure P of the supply path 40 increases. Furthermore, in order to prevent an oversupply of fluid to the discharge device 30, the supply pump 20 performs control to stop pumping the fluid to the discharge device 30 on the condition that the internal pressure P of the supply path 40 exceeds the supply pressure upper limit threshold SPH. In this way, by operating the supply pump 20 in accordance with the internal pressure P of the supply path 40 and supplying the fluid to the discharge device 30, the internal pressure P of the supply path 40 is maintained within the range of the standard supply pressure range (the range that the internal pressure P of the supply path 40 should be in to prevent an undersupply or oversupply of fluid to the discharge device 30), and the discharge of the fluid from the discharge device 30 continues.

[0066] During the step 1-1 during which the discharge device 30 is discharging the fluid, the internal pressure P of the supply path 40 is within the range of the standard supply pressure range, and therefore the pressure adjustment tank 50 is in a holding state or pressurized state, so that the fluid is not stored in the tank portion 52. Therefore, during the period during which the fluid discharging system 10 is operating normally, no fluid is introduced into the pressure adjustment tank 50.

[0067] (Step 1-2) After the normal operation is started in step 1-1 described above, it is checked in step 1-2 whether or not there is a request to stop the normal operation. If there is no request to stop the normal operation, the normal operation in step 1-1 continues. On the other hand, if a request to stop the normal operation is confirmed, the control flow proceeds to step 1-3.

[0068] Here, the control device 200 may determine that the request to stop normal operation has been turned on when a predetermined action has been taken, such as a user manually turning it on using an operating device (not shown), a signal from a control panel or the like of the production line in which the fluid dispensing system 10 is installed, a predetermined time having passed since the dispensing device 30 has stopped dispensing the fluid, or a predetermined time having passed since the dispensing device 30 or a moving device such as a robot provided to move the dispensing device 30 has reached a predetermined position (for example, the origin).

[0069] (Step 1-3) If a request to stop normal operation is confirmed in step 1-2, in step 1-3, the supply pump 20 stops pumping the fluid and the discharge device 30 stops discharging the fluid. At the same time, the control device 200 starts control to realize operation in the low pressure maintenance mode.

[0070] (Step 1-4) In step 1-4, the control device 200 checks whether the internal pressure P is equal to or less than the low-pressure control upper threshold pressure LPH. As shown in the timing chart of FIG. 5, immediately after the low-pressure maintenance mode is initiated as described above, the internal pressure P in the supply path 40 exceeds the low-pressure control upper threshold pressure LPH in the low-pressure maintenance pressure range. Furthermore, in step 1-8, which will be described later, the pressure adjustment tank 50 may be pressurized, causing the internal pressure P to rise to exceed the low-pressure control upper threshold pressure LPH. In such a state, the control device 200 advances the control flow to step 1-5 to reduce the internal pressure P in the supply path 40. On the other hand, if the internal pressure P is equal to or less than the low-pressure control upper threshold pressure LPH, the control device 200 advances the control flow to step 1-6.

[0071] (Step 1-5) If it is determined in step 1-4 above that the internal pressure P exceeds the low-pressure control upper limit threshold pressure LPH, the control device 200 controls the pressure adjustment tank 50 to a reduced pressure state in step 1-5. As a result, fluid flows into the pressure adjustment tank 50 from the supply path 40, and the internal pressure P of the supply path 40 begins to decrease, as shown in the timing chart of FIG. 5. The control flow then proceeds to step 1-9, which will be described later.

[0072] (Step 1-6) On the other hand, if it is confirmed in step 1-4 that the internal pressure P is equal to or less than the low-pressure control upper threshold pressure LPH, the control device 200 checks in step 1-6 whether the internal pressure P is below the low-pressure control lower threshold LPL. Here, if the internal pressure P is equal to or greater than the low-pressure control lower threshold LPL, the internal pressure P is within the low-pressure maintaining pressure range (LPL≦P≦LPH). Therefore, in this state, there is no need to adjust the internal pressure P using the pressure adjustment tank 50. Therefore, if the internal pressure P is equal to or greater than the low-pressure control lower threshold LPL, the control device 200 advances the control flow to step 1-7, which will be described later. On the other hand, if the internal pressure P is below the low-pressure control lower threshold LPL, the internal pressure P has dropped to a level outside the low-pressure maintaining pressure range. Therefore, when the internal pressure P is below the low-pressure control lower limit threshold LPL, the control device 200 advances the control flow to step 1-8 described below in order to increase the internal pressure P.

[0073] (Step 1-7) If the internal pressure P is equal to or greater than the low-pressure control lower limit threshold LPL in step 1-6, the control device 200 controls the pressure adjustment tank 50 to be in a holding state in step 1-7 in order to maintain the internal pressure P within the low-pressure maintaining pressure range. Thereafter, the control device 200 advances the control flow to step 1-9.

[0074] (Step 1-8) On the other hand, if the internal pressure P is below the low-pressure control lower limit threshold LPL in step 1-6, the control device 200 controls the pressure adjustment tank 50 to be pressurized in step 1-8 in order to increase the internal pressure P to a pressure within the low-pressure maintenance pressure range. Thereafter, the control device 200 advances the control flow to step 1-9.

[0075] (Step 1-9) In step 1-9, the control device 200 checks whether or not there is a request to start normal operation. If there is no request to start normal operation, the control flow returns to step 1-4. Therefore, the control relating to steps 1-4 to 1-8 described above is repeated until a request to start normal operation is issued. This continues to adjust the internal pressure P using the pressure adjustment tank 50 so that the internal pressure P is within the low-pressure maintenance pressure range (LPL≦P≦LPH). On the other hand, if a request to start normal operation is confirmed, the control flow proceeds to step 1-10 in preparation for the start of commuter driving.

[0076] Here, the control device 200 may determine that the request to start normal operation has been turned on, provided that a predetermined action has been taken, such as a user manually operating an operating device (not shown), a signal from a control panel of the production line in which the fluid dispensing system 10 is installed being turned on, or the dispensing device 30 or a moving device such as a robot provided to move the dispensing device 30 starting to move toward a predetermined position (for example, the dispensing start position).

[0077] (Step 1-10) When the control flow proceeds to step 1-10, the control device 200 starts control to realize operation in the pressure recovery mode. Specifically, the control device 200 discharges the fluid accumulated inside the pressure adjustment tank 50 into the supply path 40, thereby returning the internal pressure P of the supply path 40 toward the standard supply pressure range. In this embodiment, the fluid is discharged into the supply path 40 until the amount of fluid accumulated in the pressure adjustment tank 50 becomes zero. Then, the control flow returns to step 1-1.

[0078] Second Embodiment A fluid dispensing system 300 according to a second embodiment of the present invention will be described in detail below with reference to the drawings. In the following description, parts common to the fluid dispensing system 10 of the first embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted. In the following description, the configuration of the fluid dispensing system 300 will be described first, and then the operation of the fluid dispensing system 300 will be described.

[0079] 6, the fluid dispensing system 300, like the above-described fluid dispensing system 10, includes a supply pump 20, a discharge device 30, a supply path 40, and a pressure adjustment tank 50. Whereas the above-described fluid dispensing system 10 has the pressure adjustment tank 50 directly connected to the middle of the supply path 40, the fluid dispensing system 300 differs in that the pressure adjustment tank 50 is connected via a branch path 340. In addition, the branch path 340 is provided with a branch path valve 342. In this embodiment, the branch path 340 is connected to one of the connection ports 56b, 56c of the pressure adjustment tank 50, and the other is closed.

[0080] In the fluid discharge system 300, the pressure adjustment tank 50 not only adjusts the internal pressure P of the supply path 40, but also functions as a buffer tank that temporarily accumulates and discharges fluid to be supplied to the discharge device 30. That is, the pressure adjustment tank 50 can accumulate fluid by sucking and flowing the fluid into it. Furthermore, when the supply pump 20 stops supplying the fluid, the pressure adjustment tank 50 discharges the accumulated fluid therein, thereby enabling the continuous supply of the fluid to the discharge device 30. In the fluid discharge system 300, while the supply pump 20 is pumping the fluid, it is also possible to discharge the accumulated fluid in the pressure adjustment tank 50 and supply the fluid to the discharge device 30 at the same time. The operation of the pressure adjustment tank 50 is controlled by the control device 200 according to the remaining amount of fluid in the discharge device 30.

[0081] <Operation of the Fluid Dispensing System 300> The fluid dispensing system 300 can be operated in one or more operating modes under the control of the control device 200. Like the above-described fluid dispensing system 10, the fluid dispensing system 300 of this embodiment can be operated in two operating modes: (1) low-pressure maintenance mode and (2) pressure recovery mode. While the above-described fluid dispensing system 10 was able to operate normally using fluid pressure-fed from the supply pump 20 to the dispensing device 30, the dispensing device 30 of this embodiment can operate normally by combining the operating modes consisting of (3) pump supply mode, (4) tank accumulation mode, (5) tank supply mode, and (6) combined supply mode. The operating modes (3) to (6) are described in more detail below.

[0082] (3) Pump Supply Mode The pump supply mode is an operating mode in which fluid is supplied from the supply pump 20 to the discharge device 30 while the pressure adjustment tank 50 is in a holding state. In the pump supply mode, the control device 200 opens the valve 48 provided in the supply path 40 between the pressure adjustment tank 50 and the supply pump 20, and closes the branch path valve 342 of the branch path 340 to block the movement of fluid between the pressure adjustment tank 50 and the supply path 40. The control device 200 also controls the operation of the supply pump 20 to start and stop depending on the remaining amount of fluid in the discharge device 30 as determined by the remaining amount determining unit 90.

[0083] In this embodiment, the control device 200 controls the operation of the supply pump 20 in accordance with the amount of fluid remaining in the discharge device 30. Specifically, the control device 200 stops the operation of the supply pump 20, assuming that it is not necessary to supply fluid to the discharge device 30, on the condition that the amount of fluid remaining in the discharge device 30 is equal to or greater than a predetermined amount. On the other hand, the control device 200 operates the supply pump 20 on the condition that the amount of fluid remaining in the discharge device 30 is less than the predetermined amount.

[0084] (4) Tank Accumulation Mode Next, the tank accumulation mode will be described in detail. The tank accumulation mode is an operating mode in which fluid is accumulated (charged) in the pressure adjustment tank 50 in preparation for the tank supply mode, which will be described in detail later, while continuing to supply fluid from the supply pump 20 to the discharge device 30. The tank accumulation mode is an operating mode in which fluid is sucked into the pressure adjustment tank 50 to accumulate inside the pressure adjustment tank 50 (communicating space 58). In the tank accumulation mode, the operation of the pressure adjustment tank 50 is controlled based on the remaining amount of fluid in the pressure adjustment tank 50, which is grasped by the content amount grasping unit 55. Furthermore, in the tank accumulation mode, the discharge device 30 can continue to discharge the fluid even while the fluid is accumulating in the buffer tank.

[0085] When operating in the tank accumulation mode, the control device 200 opens the valve 48 provided in the supply path 40, enabling the supply of fluid from the supply pump 20 to the pressure adjustment tank 50. The control device 200 also controls the operation of the supply pump 20 to operate and stop depending on the remaining amount of fluid in the discharge device 30 as determined by the remaining amount determining unit 90.

[0086] Furthermore, in the tank accumulation mode, the control device 200 controls the operation of the supply pump 20 and the pressure adjustment tank 50 based on the remaining amount of fluid in the discharge device 30. Specifically, when the remaining amount of fluid in the discharge device 30 is equal to or greater than a predetermined amount, a sufficient amount of fluid is stored in the discharge device 30, and therefore the pressure adjustment tank 50 is depressurized and the fluid accumulates in the communication space 58 of the tank section 52. More specifically, the control device 200 depressurizes the pressure adjustment tank 50 while keeping the valve 48 and the branch valve 342 open. This causes the fluid to accumulate in the pressure adjustment tank 50.

[0087] On the other hand, when the remaining amount of fluid in the discharge device 30 is less than a predetermined amount, the pressure adjustment tank 50 is set to the holding state, and the accumulation of fluid in the communication space 58 is stopped. More specifically, the control device 200 opens the valve 48 to operate the supply pump 20, sets the pressure adjustment tank 50 to the holding state, and closes the branch line valve 342 of the branch line 340 to block the movement of fluid between the pressure adjustment tank 50 and the supply line 40. In this way, the control device 200 supplies the fluid pressure-fed by the supply pump 20 to the discharge device 30.

[0088] By performing such control in the tank accumulation mode, the control device 200 accumulates the fluid in the pressure adjustment tank 50 when there is a surplus of fluid remaining in the discharge device 30. That is, in the fluid discharge system 300, the control device 200 can control the operation in the tank accumulation mode by taking advantage of the fact that the pressure adjustment tank 50 can achieve a holding state.

[0089] (5) Tank Supply Mode Next, the tank supply mode will be described in detail. The tank supply mode is an operation mode in which a fluid is supplied from the pressure adjustment tank 50 to the discharge device 30 while the supply pump 20 is stopped. The tank supply mode is a mode in which the pressure adjustment tank 50 supplies the fluid to the discharge device 30 instead of the supply pump 20. Operation in the tank supply mode is an operation mode for discharging the fluid from the pressure adjustment tank 50 to the supply path 40 when the supply pump 20 is stopped, for example, to replace the storage section 22 of the supply pump 20 or to replenish the storage section 22 with the fluid, thereby enabling the continuous supply of the fluid to the discharge device 30.

[0090] In the tank supply mode, on the condition that the remaining amount of fluid in the discharge device 30 falls below a predetermined amount (lower threshold amount), the supply pump 20 is stopped, and the pressure adjustment tank 50 is pressurized with the valve 48 in a closed state and the branch valve 342 in an open state. As a result, the fluid is supplied from the pressure adjustment tank 50 to the discharge device 30 without the supply pump 20 pressurizing the fluid.

[0091] On the other hand, in the tank supply mode, the pressure adjustment tank 50 is placed in a holding state on the condition that the remaining amount of fluid in the discharge device 30 exceeds a predetermined amount (upper limit threshold amount). As a result, the control device 200 controls the operation to stop the supply of fluid from the pressure adjustment tank 50 to the discharge device 30. This prevents the discharge device 30, which is sufficiently filled with fluid, from being excessively supplied with fluid. Note that in the tank supply mode, the upper limit threshold amount can be the same as the lower limit threshold amount, or can be a predetermined amount greater than the lower limit threshold amount.

[0092] (6) Combined Supply Mode Next, the combined supply mode will be described in detail. The combined supply mode is an operating mode in which fluid is supplied to the discharge device 30 from both the supply pump 20 and the pressure adjustment tank 50. Operation in the combined supply mode is performed, for example, at the end of the tank supply mode described above, when it is assumed that the remaining amount of fluid in the tank unit 52 is running low, to supplement the supply of fluid from the pressure adjustment tank 50 to the discharge device 30 with the supply of fluid from the supply pump 20. Operation in the combined supply mode when it is assumed that the remaining amount of fluid in the tank unit 52 is running low can both stabilize the supply pressure of fluid to the discharge device 30 and use up the fluid accumulated in the pressure adjustment tank 50.

[0093] That is, in the tank supply mode, as the amount of fluid remaining in the pressure adjustment tank 50 decreases, the distance between the bottom surface of the tank main body 52a and the piston 62 narrows, resulting in increased pressure loss. This reduces the flow rate of fluid discharged from the pressure adjustment tank 50 toward the discharge device 30. If the flow rate of fluid from the pressure adjustment tank 50 to the discharge device 30 falls below the amount of fluid discharged from the discharge device 30, a shortage of fluid supply occurs. Therefore, when the amount of fluid remaining in the pressure adjustment tank 50 falls below a certain level, the operating mode is switched to the combined supply mode, and the supply pump 20, in addition to the pressure adjustment tank 50, is operated to supply fluid. This makes it possible to stabilize the supply pressure of fluid to the discharge device 30 while using up the fluid stored in the pressure adjustment tank 50.

[0094] In the combined supply mode, the operation of the supply pump 20 and the pressure adjustment tank 50 is controlled based on the remaining amount of fluid in the discharge device 30. Specifically, in the combined supply mode, when supplying fluid to the discharge device 30, the operation is controlled so that both the supply pump 20 and the pressure adjustment tank 50 supply the fluid to the discharge device 30, provided that the remaining amount of fluid in the discharge device 30 falls below a predetermined lower limit (lower limit threshold). More specifically, the control device 200 pressurizes the pressure adjustment tank 50 while opening the branch valve 342, and operates the supply pump 20 while opening the valve 48, provided that the remaining amount of fluid in the discharge device 30 falls below the lower limit threshold. In this way, the control device 200 supplies the fluid to the discharge device 30 from both the pressure adjustment tank 50 and the supply pump 20.

[0095] When fluids are supplied by both the supply pump 20 and the pressure adjustment tank 50 in the combined supply mode, it is possible to adjust which of the supply pump 20 and the pressure adjustment tank 50 is to be used preferentially by differentiating the timing at which the supply pump 20 and the pressure adjustment tank 50 start pumping the fluids. For example, if it is desired to use up all of the fluids in the pressure adjustment tank 50 in each cycle to prevent deterioration of the fluids accumulated in the pressure adjustment tank 50, the control device 200 can perform control to delay the timing at which the supply pump 20 starts pumping the fluids relative to the timing at which the pressure adjustment tank 50 starts pumping the fluids.

[0096] On the other hand, in the combined supply mode, the supply pump 20 and the pressure adjustment tank 50 are controlled to stop discharging the fluid when the remaining amount of fluid in the discharge device 30 exceeds a predetermined upper limit (upper limit threshold). More specifically, in the combined supply mode, when the remaining amount of fluid in the discharge device 30 exceeds the upper limit threshold, the supply pump 20 is stopped and the pressure adjustment tank 50 is placed in a holding state. This prevents the fluid from being excessively supplied to the discharge device 30, which is already sufficiently filled with the fluid.

[0097] [Regarding the operation of the fluid dispensing system 300] The overall operation of the fluid dispensing system 300, which is executed including the operation modes (1) to (6) described above, will be described in detail below with reference to the flowchart for normal operation shown in Fig. 7, the flowchart for the overall operation shown in Fig. 4, and the timing chart in Fig. 8. Note that in the description of the flowchart for the overall operation in Fig. 4, detailed description of steps that perform the same operations as those in the first embodiment will be omitted.

[0098] <Normal Operation of Fluid Dispensing System 300> Next, normal operation performed in the fluid dispensing system 300 will be described in detail with reference to the flowchart of FIG.

[0099] <<Normal Operation>> (Step 2-1) When the fluid discharge system 300 is operating normally, first in step 2-1, under the control of the control device 200, an operation is performed in which the fluid is supplied from the supply pump 20 to the discharge device 30 in pump supply mode. Specifically, in step 2-1, the control device 200 controls the operation so that the fluid is supplied from the supply pump 20 to the discharge device 30 while the pressure adjustment tank 50 is in a holding state. In the pump supply mode, when the remaining amount of fluid in the discharge device 30 exceeds a threshold, the supply of fluid by the supply pump 20 stops, and as the remaining amount of fluid in the discharge device 30 decreases, the operation of supplying fluid to the discharge device 30 by the supply pump 20 is repeatedly performed. When operation in the pump supply mode is started in step 2-1, the control flow proceeds to step 2-2.

[0100] (Step 2-2) In step 2-2, the control device 200 checks whether there is a request to stop operation in the pump supply mode. Specifically, when the remaining amount of fluid in the storage unit 22 falls below a predetermined threshold, the control device 200 determines that the request to stop operation in the pump supply mode has been turned on. If it is determined in step 2-2 that there is a request to stop operation in the pump supply mode, the control flow proceeds to step 2-3.

[0101] (Step 2-3) When the control flow proceeds to step 2-3, the control device 200 performs operation control to supply the fluid from the pressure adjustment tank 50 to the discharge device 30 in tank supply mode instead of pump supply mode. Specifically, in step 2-3, the control device 200 stops the supply pump 20 and closes the valve 48 provided in the supply path 40. The control device 200 also discharges the fluid accumulated in the pressure adjustment tank 50 into the supply path 40. As a result, the fluid discharge system 300 utilizes the pressure adjustment tank 50 as a buffer tank for supplying the fluid to the discharge device 30 in place of the supply pump 20. Note that while operation in the tank supply mode is being performed in step 2-3, the supply pump 20 is stopped, allowing work to be done to replenish the fluid in the reservoir 22. When operation in the tank supply mode is initiated in step 2-3, the control flow proceeds to step 2-4.

[0102] (Step 2-4) When the control flow proceeds to step 2-4, the control device 200 checks whether the remaining amount of fluid stored in the pressure adjustment tank 50 has fallen below a predetermined lower limit. If the remaining amount of fluid in the pressure adjustment tank 50 is equal to or greater than the lower limit, the control flow returns to step 2-3, and operation in the tank supply mode continues. On the other hand, if the remaining amount of fluid in the pressure adjustment tank 50 is equal to or greater than the lower limit, the control flow proceeds to step 2-5.

[0103] (Step 2-5) In step 2-5, the control device 200 controls the operation so that, instead of the tank supply mode, the control device 200 operates in a combined supply mode in which the fluid is supplied to the discharge device 30 from both the supply pump 20 and the pressure adjustment tank 50. Specifically, in step 2-5, the control device 200 controls the operation so that the fluid is supplied to the discharge device 30 by both the supply pump 20 and the pressure adjustment tank 50, on the condition that the remaining amount of the fluid in the discharge device 30 falls below a predetermined lower limit (lower limit threshold). When operation in the combined supply mode is started, the control device 200 advances the control flow to step 2-6.

[0104] (Step 2-6) When the control flow proceeds to step 2-6, the control device 200 checks whether the conditions for executing the tank accumulation mode are met. The conditions for executing the tank accumulation mode may be, for example, that the remaining amount of fluid accumulated in the pressure adjustment tank 50 falls below a predetermined minimum threshold, or that fluid has been supplied from the pressure adjustment tank 50 to the discharge device 30 a predetermined number of times since the combined supply mode was entered. If the conditions for executing the tank accumulation mode are not met, the control device 200 returns the control flow to step 2-5 and continues operation in the combined supply mode. On the other hand, if it is confirmed that the conditions for executing the tank accumulation mode are met, the control device 200 proceeds to step 2-7.

[0105] (Step 2-7) When the control flow proceeds to step 2-7, the control device 200 performs operational control to operate in the tank accumulation mode. Specifically, while continuing to supply fluid from the supply pump 20 to the discharge device 30, the control device 200 causes the fluid to flow into the pressure adjustment tank 50 via the branch path 340 and accumulate (charge) it with the branch path valve 342 in an open state. When operation in the tank accumulation mode is started, the control device 200 proceeds to step 2-8 in the control flow.

[0106] (Step 2-8) In step 2-8, the control device 200 checks whether the remaining amount of fluid in the pressure adjustment tank 50 has reached a predetermined threshold (upper accumulation amount). Here, the upper accumulation amount is set so as to ensure, as an adjustment margin, the volume necessary to accommodate the fluid in the pressure adjustment tank 50 when the internal pressure P is reduced during operation in the low-pressure control mode. Specifically, if A% of the volume of the pressure adjustment tank 50 is ensured as an adjustment margin in order to reduce the internal pressure P in the low-pressure control mode, the upper accumulation amount is set to (100-A)% of the volume of the pressure adjustment tank 50. For example, if the adjustment margin is 20% of the volume of the pressure adjustment tank 50, the upper accumulation amount is set to 80% of the volume of the pressure adjustment tank 50. Until the remaining amount of fluid in the pressure adjustment tank 50 reaches the upper accumulation amount in step 2-8, the control flow returns to step 2-7, and operation in the tank accumulation mode continues. On the other hand, if it is confirmed that the remaining amount of fluid in the pressure adjustment tank 50 has reached the upper limit accumulation amount, the control flow returns to step 2-1, and the fluid discharge system 300 starts operating in the pump supply mode instead of the tank supply mode.

[0107] <<Overall Operation of Fluid Dispensing System 300>> Next, the overall operation of the fluid dispensing system 300 will be described in detail with reference to the flowchart of FIG. 4 and the timing chart of FIG.

[0108] (Step 3-1) In step 3-1, the fluid dispensing system 300 performs normal operation. As described above, normal operation is performed by sequentially executing the operation modes consisting of (3) pump supply mode, (4) tank accumulation mode, (5) tank supply mode, and (6) combined supply mode. That is, in the fluid dispensing system 300, normal operation is performed in accordance with the flowchart shown in FIG. 7.

[0109] (Step 3-2) After normal operation is started in step 3-1 described above, it is confirmed in step 3-2 whether or not there is a request to stop normal operation. While there is no request to stop normal operation, normal operation in step 3-1 continues. On the other hand, if a request to stop normal operation is confirmed, the control flow proceeds to step 3-3. In the example shown in the timing chart of FIG. 8, in normal operation, a predetermined upper limit storage amount (e.g., 80% of the capacity of the tank section 52) of fluid is stored in the pressure adjustment tank 50, and a request to stop normal operation is confirmed during normal operation in pump supply mode. If it is confirmed in step 3-2 that there is a request to stop normal operation, the control flow proceeds to step 3-3.

[0110] (Step 3-3) In step 3-3, the control device 200 stops the pressure-feeding of the fluid by the supply pump 20 and the discharge of the fluid by the discharge device 30. At this time, in this embodiment, the branch valve 342 is opened. At the same time, the control device 200 starts control to realize operation in the low-pressure maintenance mode.

[0111] (Step 3-4) In step 3-4, the control device 200 checks whether the internal pressure P is equal to or less than the low-pressure control upper threshold pressure LPH. If the internal pressure P is greater than the low-pressure control upper threshold pressure LPH, the control device 200 advances the control flow to step 3-5. On the other hand, if the internal pressure P is equal to or less than the low-pressure control upper threshold pressure LPH, the control device 200 advances the control flow to step 3-6.

[0112] (Step 3-5) In step 3-5, the control device 200 performs control to reduce the pressure in the pressure adjustment tank 50. As a result, fluid flows from the supply path 40 into the pressure adjustment tank 50, and the internal pressure P of the supply path 40 begins to decrease. Thereafter, the control flow proceeds to step 3-9, which will be described later.

[0113] (Step 3-6) In step 3-6, the control device 200 checks whether the internal pressure P is below the low-pressure control lower limit threshold LPL. If the internal pressure P is equal to or greater than the low-pressure control lower limit threshold LPL, the control device 200 proceeds to step 3-7, which will be described later, and if the internal pressure P is below the low-pressure control lower limit threshold LPL, the control device 200 proceeds to step 3-8.

[0114] (Step 3-7) When the control flow moves from step 3-6 to step 3-7, the control device 200 controls the pressure adjustment tank 50 to be in the holding state. After that, the control device 200 advances the control flow to step 3-9.

[0115] (Step 3-8) On the other hand, when the control flow moves from step 3-6 to step 3-8, the control device 200 performs control to pressurize the pressure adjustment tank 50. After that, the control device 200 advances the control flow to step 3-9.

[0116] (Step 3-9) In step 3-9, the control device 200 checks whether or not there is a request to start normal operation. If there is no request to start normal operation, the control flow returns to step 3-4. On the other hand, if a request to start normal operation is confirmed, the control flow proceeds to step 3-10 in preparation for the start of commuting operation.

[0117] (Step 3-10) When the control flow proceeds to step 3-10, the control device 200 starts control to realize operation in the pressure recovery mode. Specifically, the control device 200 discharges the fluid accumulated inside the pressure adjustment tank 50 into the supply path 40, thereby returning the internal pressure P of the supply path 40 toward the standard supply pressure range.

[0118] Here, in this embodiment, the control device 200 does not require that the entire amount of fluid accumulated inside the pressure adjustment tank 50 be discharged to the supply line 40 in the pressure recovery mode, but rather attempts to reserve a portion of the fluid accumulated in the pressure adjustment tank 50 for use in other applications (for example, operation in the tank supply mode after the start of normal operation), while discharging the remainder to the supply line 40.

[0119] As a method for performing the above-described operation, the pressure recovery mode can be executed by discharging all of the fluid into the supply path 40 until the accumulated amount of fluid in the pressure adjustment tank 50 reaches a predetermined amount (e.g., 80% of the capacity of the tank portion 52). In this embodiment, control is performed to stop the discharge of the fluid based on the internal pressure P of the supply path 40. Specifically, the control device 200 controls the discharge until it is confirmed that the internal pressure P reaches a predetermined pressure, such as a supply pressure lower limit threshold SPL or a supply pressure upper limit threshold SPH. In this embodiment, as shown in the timing chart of FIG. 8 , the control device 200 controls the discharge until it is confirmed that the internal pressure P reaches the supply pressure lower limit threshold SPL. This allows the internal pressure P to be increased to a pressure appropriate for resuming normal operation, while the remaining fluid can be accumulated and reserved in the pressure adjustment tank 50 for other uses.

[0120] When the operation related to the pressure recovery mode is completed in step 3-10, the control flow returns to step 3-1, and normal operation is initiated. When normal operation is initiated, it is possible to appropriately specify which mode to start from: pump supply mode, tank accumulation mode, tank supply mode, or combined supply mode. For example, when the system transitioned to the low-pressure control mode in step 3-3 described above, the control device 200 may store the mode in which normal operation was performed, and resume normal operation from the stored mode. In this embodiment, since the system transitioned to the low-pressure control mode while performing normal operation in the pump supply mode in step 3-3, the supply pump 20 is operated with the branch line valve 342 of the branch line 340 connected to the pressure adjustment tank 50 closed, and the fluid is supplied to the discharge device 30, thereby resuming normal operation from the pump supply mode.

[0121] The fluid dispensing system 300 is not limited to the method of storing the mode in which normal operation was performed when the system transitioned to the low-pressure control mode as described above and resuming normal operation using the stored mode. It is also possible to resume normal operation using other methods. For example, if the system does not store the mode in which normal operation was performed when the system transitioned to the low-pressure control mode, or if the memory is lost for some reason, it may resume normal operation using a predefined mode selected from the pump supply mode, tank accumulation mode, tank supply mode, and combined supply mode. For example, if the fluid dispensing system 300 is configured to resume normal operation using the combined supply mode, it is possible to prevent insufficient fluid supply to the dispensing device 30 and delayed response.

[0122] Third Embodiment A fluid dispensing system 600 according to a third embodiment of the present invention will be described in detail below with reference to the drawings. In the following description, parts common to the fluid dispensing system 10 of the first embodiment and the fluid dispensing system 300 of the second embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted.

[0123] The fluid discharge system 600 of the third embodiment has the same basic configuration as the fluid discharge system 10 of the first embodiment. As shown in Fig. 1, the fluid discharge system 600 is configured such that a supply pump 20 and a discharge device 30 are connected by a supply path 40. The fluid discharge system 600 is configured such that a pressure adjustment tank 50 is provided midway through the supply path 40. The fluid discharge system 600 also includes a control device 200 for controlling the operation of the supply pump 20, the discharge device 30, and the pressure adjustment tank 50.

[0124] The fluid dispensing system 600 differs from the fluid dispensing system 300 according to the second embodiment in that the fluid dispensing system 600 does not have the branch valve 342. That is, in the fluid dispensing system 600 according to the third embodiment, the pressure adjustment tank 50 is always connected to the supply path 40, and fluid can always flow in and out between the supply path 40 and the pressure adjustment tank 50.

[0125] In the fluid dispensing system 600, similar to the fluid dispensing system 300, the operation of the pressure adjustment tank 50 is controlled by the control device 200 in accordance with the remaining amount of fluid in the dispensing device 30. The pressure adjustment tank 50 functions as a buffer tank that temporarily stores and discharges the fluid to be supplied to the dispensing device 30.

[0126] The pressure adjustment tank 50 has the same configuration as in the first and second embodiments, and includes a tank portion 52, a volume fluctuation mechanism 54, and an internal volume determination portion 55. The internal volume determination portion 55 is capable of detecting the amount of fluid stored in the pressure adjustment tank 50 (internal volume), and is configured by a sensor such as a linear encoder that detects the position of the piston portion 62, for example.

[0127] In the fluid dispensing system 600 of the third embodiment, the control device 200 is operable in two operation modes, (1) low pressure maintenance mode and (2) pressure recovery mode, as in the fluid dispensing system 300, as well as in operation modes consisting of (3) pump supply mode, (4) tank accumulation mode, (5) tank supply mode, and (6) combined supply mode. That is, the control device 200 can control operation so as to execute a combination of the operation modes (3) to (6) during normal operation.

[0128] Compared to the control device 200 of the fluid discharge system 300, the control device 200 has a new function for managing and controlling the amount of fluid accumulated in the pressure adjustment tank 50. The control device 200 is capable of setting two thresholds for the amount of fluid accumulated in the pressure adjustment tank 50, above and below a basic upper accumulation threshold (e.g., 80% of the capacity of the tank section 52). Specifically, as shown in FIG. 9 , in addition to the basic upper accumulation threshold, the control device 200 is capable of setting an upper limit tolerable fluctuations in the amount of fluid accumulated (e.g., 85% of the capacity of the tank section 52) and a lower limit tolerable fluctuations in the amount of fluid accumulated (e.g., 75% of the capacity of the tank section 52). With this configuration, the control device 200 can appropriately manage the amount of fluid accumulated in the pressure adjustment tank 50 in each operating mode of the fluid discharge system 600 using each threshold.

[0129] Next, the operation of the fluid dispensing system 600 will be described in more detail. The fluid dispensing system 600 of the third embodiment can be operated in one or more operation modes, similar to the fluid dispensing system 300. As described above, the fluid dispensing system 600 can be operated in six operation modes: (1) low pressure maintenance mode, (2) pressure recovery mode, (3) pump supply mode, (4) tank accumulation mode, (5) tank supply mode, and (6) combined supply mode. Of the operation modes, the operation modes except for (3) pump supply mode are basically the same as the operation modes of the fluid dispensing system 300, except that the opening and closing of the branch valve 342 is not controlled in the operation modes of the fluid dispensing system 300.

[0130] On the other hand, (3) the pump supply mode includes a control different from that of the pump supply mode of the fluid delivery system 300. The pump supply mode of the fluid delivery system 600 will be described in detail with reference to the flowchart shown in Fig. 10. Fig. 10 shows the control of temporary mode switching that is executed in the pump supply mode when the accumulated amount of fluid temporarily changes.

[0131] The pump supply mode of the third embodiment is an operating mode in which fluid is supplied from the supply pump 20 to the discharge device 30 in a state in which the flow of fluid into and out of the pressure adjustment tank 50 is not restricted by the branch channel valve 342. In this pump supply mode, if the pressure in the supply channel 40 fluctuates, the amount of fluid accumulated in the pressure adjustment tank 50 fluctuates in conjunction with the pressure fluctuation in the supply channel 40, unlike the second embodiment which is equipped with a branch channel valve. Therefore, in the third embodiment, the amount of fluid accumulated in the pressure adjustment tank 50 is appropriately managed by temporarily switching to another mode when the fluctuation in the accumulated amount exceeds a predetermined range.

[0132] Specifically, in the pump supply mode, the control device 200 determines whether the amount of accumulated fluid in the pressure adjustment tank 50 has exceeded the allowable upper limit of accumulated amount fluctuation (e.g., 85% of the capacity of the tank section 52) (step 4-1). If the amount of accumulated fluid exceeds the allowable upper limit, the control device 200 initiates the temporary tank supply mode (step 4-2). The temporary tank supply mode is a mode for discharging the fluid from the pressure adjustment tank 50 when the accumulated amount becomes excessive, thereby restoring the accumulated amount to an appropriate range.

[0133] When the temporary tank supply mode is initiated, the control device 200 pressurizes the pressure adjustment tank 50. This causes the fluid in the pressure adjustment tank 50 to be discharged into the supply path 40, reducing the amount of fluid stored in the pressure adjustment tank 50. The control device 200 determines whether a basic upper limit accumulation threshold (e.g., 80% of the capacity of the tank section 52) has been reached (step 4-3). If the basic upper limit accumulation threshold (hereinafter also referred to as the "basic upper limit accumulation threshold") has not been reached, the temporary tank supply mode of step 4-2 continues. On the other hand, if the basic upper limit accumulation threshold has been reached, the control device 200 ends the temporary tank supply mode and then returns to the pump supply mode (step 4-4).

[0134] On the other hand, if the accumulated amount of fluid is equal to or less than the upper limit of tolerance in step 4-1, the control device 200 determines whether the accumulated amount has fallen below the lower limit of tolerance for fluctuations in the accumulated amount (for example, 75% of the capacity of the tank unit 52) ​​(step 4-5). If the accumulated amount of fluid falls below the lower limit of tolerance, the control device 200 initiates a temporary tank accumulation mode (step 4-6). The temporary tank accumulation mode is a mode in which, when the accumulated amount is insufficient, fluid is flowed from the supply path 40 into the pressure adjustment tank 50 to return the accumulated amount to within the appropriate range.

[0135] When the temporary tank accumulation mode is initiated, the control device 200 reduces the pressure in the pressure adjustment tank 50. This causes the fluid in the supply line 40 to flow into the pressure adjustment tank 50, increasing the amount of fluid accumulated in the pressure adjustment tank 50. The control device 200 determines whether the basic upper limit accumulation threshold has been reached (step 4-7). If the basic upper limit accumulation threshold has not been reached, the control device 200 continues the temporary tank accumulation mode initiated in step 4-6. On the other hand, if the basic upper limit accumulation threshold has been reached, the control device 200 ends the temporary tank accumulation mode and subsequently returns to the pump supply mode (step 4-8).

[0136] If the accumulated amount of fluid is equal to or greater than the allowable lower limit in step 4-6, or if the temporary tank accumulation mode is terminated in step 4-8, the accumulated amount is within the appropriate range, and therefore the control device 200 continues the pump supply mode (step 4-9).

[0137] In this way, the fluid discharge system 600 monitors the amount of fluid accumulated in the pressure adjustment tank 50 under the control of the control device 200, and by temporarily switching to another mode if the accumulated amount deviates from a predetermined range, the amount of fluid accumulated in the pressure adjustment tank 50 can be appropriately managed even if the branch valve 342 is not provided.

[0138] Furthermore, in the fluid discharge system 600, by appropriately managing the amount of fluid accumulated in the pressure adjustment tank 50, it is possible to ensure the amount of fluid necessary for alternative supply while also ensuring the free capacity necessary to execute the low pressure maintenance mode. This makes it possible to achieve both the low pressure maintenance mode and the alternative supply functions without using a branch valve.

[0139] According to the fluid dispensing system 600 of the third embodiment described above, it is possible to store fluid for alternative supply while ensuring the necessary free capacity in the pressure adjustment tank 50 for the low pressure maintenance mode, without using the branch valve 342. This makes it possible to reduce consumable parts such as valves, improve maintainability, and reduce parts costs.

[0140] <Effects Obtained by the Fluid Dispensing Systems 10, 300, 600> The fluid dispensing systems 10, 300, 600 exemplified as the first, second, and third embodiments above have the following characteristic configurations (a) to (g). As a result, the fluid dispensing systems 10, 300, 600 can achieve the unique effects described below.

[0141] (a) The fluid discharge systems 10, 300, 600 have a discharge device 30 that performs a discharge operation to discharge a fluid, a supply pump 20 that can supply the fluid toward the discharge device 30, a supply path 40 that connects the discharge device 30 and the pump so that the fluid can pass through, a pressure adjustment tank 50 that can allow the fluid to flow in and out of the supply path 40 midway, and a control device 200 that controls the internal pressure P of the supply path 40 by adjusting the flow of fluid in and out of the pressure adjustment tank 50, and by controlling the flow of fluid in and out of the pressure adjustment tank 50 using the control device 200, a low pressure maintenance mode can be implemented in which the internal pressure P of the supply path 40 during a stop period when the discharge operation is stopped is maintained at a pressure lower than the standard range of the internal pressure P of the supply path 40 during a discharge period when the discharge operation is performed.

[0142] The fluid dispensing systems 10, 300, and 600 include a pressure adjustment tank 50 disposed midway through a supply line 40 connecting the dispensing device 30 and the supply pump 20, allowing the inflow and outflow of fluid. The fluid dispensing systems 10, 300, and 600 are capable of controlling the internal pressure P of the supply line 40 by adjusting the inflow and outflow of fluid in the pressure adjustment tank 50 under the control of the control device 200. Furthermore, the fluid dispensing systems 10, 300, and 600 can control the internal pressure P of the supply line 40 to be lower than the standard range of the internal pressure P of the supply line 40 during the dispensing period by adjusting the inflow and outflow of fluid in the pressure adjustment tank 50 through control in a low-pressure maintenance mode. Therefore, the fluid dispensing systems 10, 300, and 600 can reduce the pressure in the piping system, including the supply line 40, to an appropriate level when no fluid is being dispensed.

[0143] (b) In the fluid discharge system 10, 300, 600, the control device 200, in a low pressure maintenance mode, controls the inflow and outflow of fluid in the pressure adjustment tank 50 so that the internal pressure P of the supply line 40 is maintained within a low pressure maintenance pressure range that is lower than the standard range. Under the condition that the internal pressure P of the supply line 40 exceeds the upper threshold of the low pressure maintenance pressure range or is expected to exceed the upper threshold, the internal pressure P of the supply line 40 is reduced by introducing fluid into the pressure adjustment tank 50, and under the condition that the internal pressure P of the supply line 40 is below the lower threshold of the low pressure maintenance pressure range or is expected to fall below the lower threshold, the fluid in the pressure adjustment tank 50 is discharged into the supply line 40 to pressurize the supply line 40.

[0144] By adopting the configuration according to (b) above, the fluid discharge systems 10, 300, 600 can prevent the internal pressure P of the supply path 40 from deviating from the range of the low-pressure maintenance pressure region and becoming high or low in the low-pressure maintenance mode. As a result, when not discharging a fluid, the fluid discharge systems 10, 300, 600 can stabilize the pressure within the low-pressure maintenance pressure region while reducing the pressure inside the piping system made up of the supply path 40, etc. to an appropriate level.

[0145] (c) In the fluid dispensing systems 10, 300, and 600, the control device 200 controls the pressure in the supply passage 40 to be maintained higher than atmospheric pressure in the low pressure maintenance mode.

[0146] By adopting the configuration according to (c) above, the fluid dispensing systems 10, 300, 600 can prevent air from being trapped in the supply passage 40 when the low pressure maintenance mode is executed.

[0147] (d) In the fluid discharge systems 10, 300, and 600, the control device 200 can execute control in a pressure recovery mode in which the fluid in the pressure adjustment tank 50 is discharged into the supply path 40 to pressurize the supply path 40 before the discharge device 30, which has stopped discharging, resumes discharging operation.

[0148] By configuring the fluid dispensing systems 10, 300, 600 to have a pressure recovery mode as described above (d), it is possible to improve the dispensing response when the dispensing operation is restarted.

[0149] (e) The fluid discharge systems 10, 300, and 600 are suitable for use in supplying and discharging a slurry liquid as a fluid.

[0150] As described above, the fluid dispensing systems 10, 300, and 600 can control the internal pressure P of the supply path 40 to be lower than the standard range of the internal pressure P of the supply path 40 during the dispensing period during the stop period when the dispensing device 30 stops dispensing. Therefore, even when the fluid dispensing systems 10, 300, and 600 are used to supply and discharge a slurry liquid as a fluid, they can suppress the occurrence of phenomena that adversely affect dispensing and application, such as the caking phenomenon described above.

[0151] (f) In the fluid discharge systems 10, 300, and 600, the pressure adjustment tank 50 can supply fluid to the discharge device 30 as an alternative when the supply pump 20 stops, or can supply fluid in combination with the supply pump 20.

[0152] By configuring the fluid discharge systems 10, 300, 600 as described above in (f), even if the supply pump 20 stops while the discharge device 30 is in operation, the discharge operation can be continued without interruption by supplying a substitute fluid from the pressure adjustment tank 50 to the discharge device 30.

[0153] In the above-described fluid discharge systems 10, 300, 600, when configured as in (f) above, the operation of the pressure adjustment tank 50 to supply fluid to the discharge device 30 in place of the supply pump 20 or in combination with the supply pump 20 while the discharge device 30 is in operation (alternative supply) is preferably performed with the start condition being that the supply pump 20 stops while the discharge device 30 is in operation, as exemplified in the above embodiment. Note that the start condition for the alternative supply may be other conditions in addition to or instead of the supply pump 20 stopping while the discharge device 30 is in operation.

[0154] (g) In the fluid discharge systems 10, 300, and 600, the pressure adjustment tank 50 is provided with a content volume grasping unit 55 that grasps the content volume of the fluid within the pressure adjustment tank 50, and when the control device 200 accumulates fluid in the pressure adjustment tank 50 for alternative supply, the content volume grasping unit 55 grasps the content volume, and controls the accumulated amount of fluid so as to ensure free capacity for the inflow of fluid to reduce the internal pressure P of the supply path 40 in the low pressure maintenance mode.

[0155] By adopting the configuration according to (g) above, the fluid discharge systems 10, 300, 600 can secure the free capacity required to operate in the low pressure maintenance mode in the internal pressure P adjustment tank, while storing fluid in the internal pressure P adjustment tank in preparation for alternative supply. This allows the fluid discharge systems 10, 300, 600 to achieve both operation in the low pressure maintenance mode and alternative supply using the same pressure adjustment tank 50.

[0156] In particular, the fluid dispensing system 600 according to the third embodiment can appropriately manage the amount of fluid accumulated in the pressure adjustment tank 50 without using the branch valve 342. The fluid dispensing system 600 sets dual thresholds (upper and lower allowable limits for fluctuations in the accumulated amount) in addition to the basic upper accumulation threshold for the accumulated amount in the pressure adjustment tank 50, and controls the system to temporarily switch modes when the accumulated amount deviates from the allowable range, thereby achieving both the low-pressure maintenance mode and the alternative supply mode without a valve. This allows the fluid dispensing system 600 to reduce consumable parts such as valves, improving maintainability and reducing parts costs.

[0157] <<Variations>> The above-described fluid dispensing systems 10, 300, and 600 merely represent one embodiment of the present invention, and are not limited to those exemplified in the above embodiment. The configuration and control can be modified as appropriate as long as they do not deviate from the spirit of the present invention.

[0158] For example, as described above in (b), the fluid discharge systems 10, 300, and 600 define a low-pressure maintenance pressure range in which the internal pressure P of the supply path 40 is lower than the standard range in the low-pressure maintenance mode, and adjust the inflow and outflow of fluid using the pressure adjustment tank 50 to control the internal pressure P so that it falls within the pressure range between the low-pressure control lower threshold LPL and the low-pressure control upper threshold LPH, but the present invention is not limited to this. For example, in the low-pressure maintenance mode, it is also possible to control the operation of the pressure adjustment tank 50 using a specific pressure value as a target value rather than a specific pressure range.

[0159] As described above in (c), the fluid dispensing systems 10, 300, and 600 control the pressure in the supply path 40 to be higher than atmospheric pressure in the low-pressure maintenance mode, but the present invention is not limited to this. For example, the fluid dispensing systems 10, 300, and 600 can also control the pressure in the supply path 40 to be maintained at atmospheric pressure or a pressure below atmospheric pressure in the low-pressure maintenance mode. In this case, it is desirable to take structural or control measures to prevent gas such as air from entering the supply path 40 and causing air entrapment when the low-pressure maintenance mode is executed.

[0160] Although the fluid dispensing systems 10, 300, and 600 are capable of executing control in the pressure recovery mode as described above in (d), the present invention is not limited to this. For example, the fluid dispensing systems 10, 300, and 600 may not execute control in the pressure recovery mode. This configuration simplifies the control of the fluid dispensing systems 10, 300, and 600. In addition, when such a configuration is used, it is advisable to take structural or control measures to improve the dispensing responsiveness when the dispensing operation is resumed.

[0161] Although the fluid discharge systems 10, 300, and 600 are configured to supply and discharge a slurry liquid as a fluid as described above (e), the present invention is not limited to this. The fluid discharge systems 10, 300, and 600 are not limited to the above-described slurry liquid, and can be suitably used in cases where the fluid should not be exposed to a high-pressure environment for a long period of time.

[0162] As described above in (f), the fluid discharge systems 10, 300, and 600 are capable of supplying fluid to the discharge device 30 by the pressure adjustment tank 50 instead of the supply pump 20 when the supply pump 20 stops during operation of the discharge device 30, but the present invention is not limited to this, and it is also possible not to perform alternative supply by the pressure adjustment tank 50. Note that in such a configuration, it is preferable to provide a plurality of supply pumps 20 so that even if the supply pump 20 used to pressure-feed the fluid stops, the fluid can be alternatively supplied by another device or method.

[0163] The fluid dispensing systems 10, 300, and 600 are configured to ensure free space for the inflow of fluid in order to reduce the internal pressure P of the supply path 40 in the low-pressure maintenance mode when storing fluid in the pressure adjustment tank 50 for alternative supply, as described in (g) above, but the present invention is not limited to this. The fluid dispensing systems 10, 300, and 600 may also be configured without the configuration described in (g) above.

[0164] Although the fluid discharge system 600 according to the third embodiment temporarily switches modes when the accumulated amount exceeds a predetermined range, the present invention is not limited to this. For example, the fluid discharge system 600 may be configured to switch modes only when the accumulated amount reaches or falls below a certain threshold. Furthermore, when the accumulated amount exceeds the allowable upper limit, the fluid discharge system 600 may be configured to supply fluid from both the supply pump 20 and the pressure adjustment tank 50 in a temporary combined supply mode, rather than switching only to the temporary tank supply mode. This allows for more stable supply of fluid to the discharge device 30, while appropriately managing the accumulated amount in the pressure adjustment tank 50.

[0165] In the third embodiment, the fluid discharge system 600 is exemplified as one in which the upper and lower allowable limits of the accumulation amount fluctuation are set to 85% and 75% of the capacity of the tank section 52, respectively, but the present invention is not limited to this. The upper and lower allowable limits of the accumulation amount fluctuation can be set appropriately depending on the required free space and accumulation amount.

[0166] The present invention is not limited to the above-described embodiments and variations thereof, and other embodiments may be possible within the scope of the claims. The components of the above-described embodiments may be arbitrarily selected and combined. Furthermore, any component of the embodiments may be arbitrarily combined with any component described in the Summary of the Invention or any component embodying any component described in the Summary of the Invention. The present invention intends to obtain rights to these as well through amendments to this application or divisional applications, etc.

[0167] The present invention can be suitably used in all fluid discharge systems for pumping and discharging fluids.

[0168] 10: Fluid discharge system 20: Pump 22: Storage section 30: Discharge device 40: Supply path 50: Buffer tank 52: Tank section 54: Volume variation mechanism 58: Communicating space 60: Non-communicating space 62: Piston section (partition section) 64: Drive section

Claims

1. A fluid discharge system comprising: a discharge device that performs a discharge operation to discharge a fluid; a supply pump that can supply the fluid toward the discharge device; a supply path that connects the discharge device and the pump so that the fluid can pass through; a pressure adjustment tank that can allow the fluid to flow in and out of the supply path midway; and a control device that controls the internal pressure of the supply path by adjusting the flow of fluid in and out of the pressure adjustment tank, wherein a low pressure maintenance mode can be executed in which the internal pressure of the supply path during a stop period in which the discharge operation is stopped is maintained at a pressure lower than the standard range of internal pressure of the supply path during a discharge period in which the discharge operation is performed, by controlling the flow of fluid in and out of the pressure adjustment tank using the control device.

2. The fluid discharge system described in claim 1, characterized in that in the low pressure maintenance mode, the control device controls the inflow and outflow of fluid in the pressure adjustment tank so that the internal pressure of the supply line is maintained within a low-pressure maintenance pressure range that is lower than the standard range, and reduces the internal pressure of the supply line by introducing fluid into the pressure adjustment tank, provided that the internal pressure of the supply line is above an upper threshold of the low-pressure maintenance pressure range or is expected to exceed the upper threshold, and discharges the fluid in the pressure adjustment tank into the supply line to pressurize the supply line, provided that the internal pressure of the supply line is below a lower threshold of the low-pressure maintenance pressure range or is expected to fall below the lower threshold.

3. A fluid dispensing system according to claim 1 or 2, characterized in that the control device controls the pressure in the supply passage to be maintained higher than atmospheric pressure in the low pressure maintenance mode.

4. A fluid dispensing system as described in claim 1 or 2, characterized in that the control device can execute control in a pressure recovery mode in which the fluid in the pressure adjustment tank is discharged into the supply path to pressurize the supply path before the dispensing device, which has stopped dispensing operation, resumes dispensing operation.

5. A fluid discharge system according to claim 1 or 2, characterized in that a slurry liquid is supplied as the fluid and discharged.

6. A fluid discharge system as described in claim 1 or 2, characterized in that the pressure adjustment tank is capable of supplying fluid to the discharge device in place of the supply pump or in combination with the supply pump while the discharge device is in operation.

7. A fluid discharge system as claimed in claim 6, wherein the pressure adjustment tank is provided with a content volume grasping unit that grasps the content volume of the fluid within the pressure adjustment tank, and the control device grasps the content volume using the content volume grasping unit when accumulating fluid in the pressure adjustment tank for the alternative supply, and controls the accumulated amount of fluid so as to ensure free space for the inflow of fluid to reduce the internal pressure of the supply path in the low pressure maintenance mode.

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