Pressurizing device

Abstract

To provide a pressure device that can suppress the temporary suspension of the drive of a main cylinder mechanism.SOLUTION: A pressure device includes: multiple plunger pumps (20A, 20B); and a main cylinder mechanism that is connected to allow delivery and suction of working fluid from the multiple plunger pumps. The plunger pump that does not exchange working fluid with the main cylinder mechanism in a first operation pattern among the multiple plunger pumps performs a preparatory operation (J61 to J63) according to a second operation pattern before the switching timing on the basis of the switching timing (t61 to t63) at which the operation pattern of the main cylinder mechanism switches from the first operation pattern to the second operation pattern.SELECTED DRAWING: Figure 9

Description

[[Technical Field]]

[0001] The present invention relates to a pressurizing device. [[Background Art]]

[0002] Conventionally, there is known a pressurizing device in which a main cylinder mechanism is driven to pressurize by supplying working fluid from a plunger pump to the main cylinder mechanism. Patent Document 1 describes a device in which a plurality of fluid pumps are connected to one main pump unit. [[Prior Art Documents]] [[Patent Documents]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Application Publication No. 2020-099919 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] There is a limit to the amount of working fluid that a plunger pump can continuously deliver, and similarly, there is a limit to the amount of working fluid that a plunger pump can continuously suck. Therefore, when the main cylinder mechanism is driven for pressurization, if the plunger pump reaches the delivery limit of working fluid, the driving of the main cylinder mechanism will be temporarily stopped. Similarly, when the main cylinder mechanism is driven for pressure reduction, if the plunger pump reaches the suction limit of working fluid, the driving of the main cylinder mechanism will also be temporarily stopped.

[0005] The above situation also occurs in a configuration having a plurality of plunger pumps when all of the plurality of plunger pumps reach the working fluid delivery limit, or when all of the plurality of plunger pumps reach the working fluid suction limit.

[0006] An object of the present invention is to provide a pressurizing device capable of suppressing temporary stoppage of the driving of the main cylinder mechanism. [Means for solving the problem]

[0007] The pressurizing device according to the present invention is Multiple plunger pumps, A main cylinder mechanism connected to the plurality of plunger pumps so as to be able to deliver and draw in working fluid, Equipped with, Based on the switching timing at which the operating pattern of the main cylinder mechanism switches from the first operating pattern to the second operating pattern, before the switching timing, the plunger pumps among the plurality of plunger pumps that do not exchange working fluid with the main cylinder mechanism in the first operating pattern perform a preparatory operation corresponding to the second operating pattern. stomach, The plunger pump requires preparation time to change the position of the plunger between the ready-to-dispense position and the ready-to-suction position. In the first operating pattern, a plunger pump that does not exchange working fluid with the main cylinder mechanism starts the preparation operation before the preparation time from the switching timing. . [Effects of the Invention]

[0008] According to the present invention, the effect of preventing the main cylinder mechanism from being temporarily stopped is obtained. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows the overall configuration of the pressurizing device according to this embodiment. [Figure 2] This figure shows an example of the settings for the drive process of the main cylinder mechanism. [Figure 3] This diagram illustrates an example of continuous pressurized drive of the main cylinder mechanism. [Figure 4] This diagram illustrates an example of continuous pressure reduction drive of the main cylinder mechanism. [Figure 5] This diagram illustrates the preparatory actions taken before switching operation patterns. [Figure 6] This diagram illustrates the positions of the plungers in the first and second plunger pumps. [Figure 7] This is the first part of the flowchart for the control process of the main cylinder mechanism executed by the control unit. [Figure 8] This is the second part of the flowchart for the control process of the main cylinder mechanism executed by the control unit. [Figure 9] This is a timing chart showing an example of the operation of a pressurizing device. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described in detail below with reference to the drawings.

[0011] [Outline configuration of the pressurizing device] Figure 1 shows the overall configuration of the pressurizing device 1 according to this embodiment. As shown in the figure, the pressurizing device 1 comprises a main cylinder mechanism 10 that pressurizes an object to be pressurized by supplying a working fluid, a first plunger pump 20A and a second plunger pump 20B that supply working fluid to the main cylinder mechanism 10 or draw working fluid from the main cylinder mechanism 10, a fluid pump 32 connected to a working fluid tank 33 that supplies working fluid to the main cylinder mechanism 10, the first plunger pump 20A and the second plunger pump 20B, a fluid circuit connecting the above components, and a control unit 90 that controls the overall configuration of the pressurizing device 1. The working fluid is specifically a liquid, and more specifically, a hydraulic oil can be applied.

[0012] [Main cylinder mechanism] The main cylinder mechanism 10 includes a fixed pressurizing platform 11 and a movable pressurizing platform 12 that face each other and apply pressure to each other, a cylinder 13 in which working fluid is supplied and discharged, a piston 14 that slides inside the cylinder 13 along the pressurizing direction of the movable pressurizing platform 12, and a piston rod 15 that extends from the piston 14 to the outside of the cylinder 13 and is connected to the movable pressurizing platform 12. The main cylinder mechanism 10 is of double-acting type, and working fluid is supplied to and discharged from a lower region (first region) 16 and an upper region (second region) 17 inside the cylinder 13 with the piston 14 interposed therebetween. When the working fluid is supplied to the lower region 16 of the cylinder 13, the movable pressure platen 12 moves toward the fixed pressure platen 11 via the piston 14, and pressurization is performed between the fixed pressure platen 11 and the movable pressure platen 12. When the working fluid is supplied to the upper region 17 of the cylinder 13, the movable pressure platen 12 is separated from the fixed pressure platen 11 via the piston 14, and the pressurized state is released.

[0013] The main cylinder mechanism 10, for example, presses a plurality of anvils to perform ultra-high pressure pressurization on an object to be pressurized. Eight substantially cubic inner anvils and a pair of outer anvils that assemble and hold the eight inner anvils into a cubic shape are used, the pair of outer anvils are arranged between the fixed pressure platen 11 and the movable pressure platen 12, and the inner anvils are pressurized. Corners of the inner anvils are flatly chamfered, and when the eight inner anvils are assembled into a cubic shape, the object to be pressurized is arranged so as to be surrounded from eight directions by the flat portions at the corners of each inner anvils located at the inner center. Accordingly, when the main cylinder mechanism 10 pressurizes the pair of outer anvils with high pressure, pressure is intensively generated at the flat portions of the corners of the eight inner anvils, and ultra-high pressure pressurization is performed on the object to be pressurized surrounded by the flat portions. When performing the above-described ultra-high pressure pressurization, it is required to increase the pressure of the main cylinder mechanism 10 precisely and stably over time.

[0014] It should be noted that the ultra-high pressure pressurization of the object to be pressurized using anvils is merely an example of an application of the main cylinder mechanism 10, and the application is not limited thereto. It goes without saying that the main cylinder mechanism 10 may be used for other applications where other stable pressurization is performed.

[0015] [Hydraulic Cylinder Mechanism] Regarding the configuration of the first plunger pump 20A and the second plunger pump 20B which have the same structure, description will be given with the same reference numerals in principle. The first plunger pump 20A comprises a hollow cylindrical first cylinder 21A, a plunger (piston) 22 that can slide inside the first cylinder 21A, a ball screw mechanism 24 as a linear motion mechanism that imparts forward and backward movement to the plunger 22, and a servo motor 23A with a reduction gear that serves as the driving source for the ball screw mechanism 24.

[0016] The second plunger pump 20B comprises a hollow cylindrical second cylinder 21B, a plunger (piston) 22 that can slide inside the second cylinder 21B, a ball screw mechanism 24 as a linear motion mechanism that imparts forward and backward movement to the plunger 22, and a servo motor 23B with a reduction gear that serves as the driving source for the ball screw mechanism 24.

[0017] The first plunger pump 20A and the second plunger pump 20B are both single-acting cylinder mechanisms, and the working fluid is supplied and discharged within the region sealed by the plunger 22 in the first and second cylinders 21A and 21B. The ball screw mechanism 24 includes a ball screw 25 that is rotationally driven by servo motors 23A and 23B with reduction gears, and a movable frame 27 equipped with a ball nut 26 that is screwed onto the ball screw 25. The ball screw 25 is provided parallel to the stroke direction of the plunger, and the movable frame 27 is fixedly connected to the outer end of the plunger 22. The servo motors with reduction gears 23A and 23B are equipped with encoders (not shown) that input the amount of rotation (rotation angle) of the servo motors with reduction gears 23A and 23B to the control unit 90. Therefore, the control unit 90 is capable of controlling minute amounts of rotation (rotation angle) of the servo motors with reduction gears 23A and 23B. As a result, the control unit 90 controls the minute amount of movement of the plunger 22 in the stroke direction via the ball screw mechanism 24 from the servo motors 23A and 23B with reduction gears, enabling precise and high-precision control of the supply and discharge amounts of working fluid in the first and second cylinders 21A and 21B. Furthermore, by precisely controlling the amount of working fluid supplied to the main cylinder mechanism 10, the pressurizing force of the main cylinder mechanism 10 can be precisely and high-precision controlled, enabling, for example, precise pressurization, pressurization maintenance, and depressurization over long periods of time.

[0018] The ball screw mechanism 24 may also be provided with forward and backward movement on the first and second cylinders 21A and 21B, rather than on the plunger 22. Furthermore, the plungers of each plunger pump 20A and 20B may be configured in any way. Furthermore, the linear motion mechanism is not limited to a ball screw mechanism; other linear drive means, such as a linear motor, may also be used.

[0019] [Fluid pump] The fluid pump 32 is connected to a working fluid tank 33 in which working fluid is stored, and uses a motor 34 as a driving source to supply the working fluid in the working fluid tank 33 to the main cylinder mechanism 10, the first plunger pump 20A, and the second plunger pump 20B at a predetermined supply pressure.

[0020] [Fluid circuit] The fluid circuit includes a first supply valve 41 for switching the connection state from the fluid pump 32 to the main cylinder mechanism 10, a second supply valve 42 for switching the connection state from the fluid pump 32 to the first plunger pump 20A and the second plunger pump 20B, a first supply / discharge pipe 43 for allowing the working fluid to flow between the fluid pump 32 and the first supply valve 41, a second supply / discharge pipe 44 for allowing the working fluid to flow between the first supply valve 41 and the lower region 16 of the main cylinder mechanism 10, and a third supply / discharge pipe 45 for allowing the working fluid to flow between the first supply valve 41 and the upper region 17 of the main cylinder mechanism 10.

[0021] Furthermore, the fluid circuit includes a fourth supply / discharge pipe 46 that branches off from the first supply / discharge pipe 43 and connects the fluid pump 32 and the second supply valve 42 in a way that allows the working fluid to flow through it; a fifth supply / discharge pipe 47 that connects the second supply valve 42 and the first plunger pump 20A in a way that allows the working fluid to flow through it; a sixth supply / discharge pipe 48 that connects the second supply valve 42 and the second plunger pump 20B in a way that allows the working fluid to flow through it; a seventh supply / discharge pipe 49 that connects the first plunger pump 20A and the lower region 16 of the main cylinder mechanism 10 in a way that allows the working fluid to flow through it; and an eighth supply / discharge pipe 50 that connects the second plunger pump 20B and the lower region 16 of the main cylinder mechanism 10 in a way that allows the working fluid to flow through it. Furthermore, the fifth supply / discharge pipe 47 and the sixth supply / discharge pipe 48 merge on the side of the second supply valve 42, and the seventh supply / discharge pipe 49 and the eighth supply / discharge pipe 50 merge on the side of the main cylinder mechanism 10.

[0022] The first supply valve 41 can selectively connect the lower region 16 and the upper region 17 of the main cylinder mechanism 10 to the fluid pump 32 side and the working fluid tank 33 side. In other words, the first supply valve 41 can be switched between three positions: one in which the lower region 16 of the main cylinder mechanism 10 is connected to the fluid pump 32 and the upper region 17 is connected to the working fluid tank 33; another in which the lower region 16 of the main cylinder mechanism 10 is connected to the working fluid tank 33 and the upper region 17 is connected to the fluid pump 32; and a third in which both the lower region 16 and the upper region 17 of the cylinder 13 of the main cylinder mechanism 10 are connected to the working fluid tank 33.

[0023] The second supply valve 42 can selectively connect the first plunger pump 20A and the second plunger pump 20B to the fluid pump 32 side and the working fluid tank 33 side. In other words, the second supply valve 42 can be switched between a position where the junction end of the fifth supply / discharge pipe 47 connected to the first plunger pump 20A and the sixth supply / discharge pipe 48 connected to the second plunger pump 20B is connected to the working fluid tank 33 side, and a position where the junction end is connected to the fluid pump 32 side.

[0024] Relief valves are provided in each of the supply and discharge pipes 43-45, 47, and 48. Furthermore, a pilot check valve 51 is provided at the end of the second supply / discharge pipe 44 on the first supply valve 41 side, and a pressure sensor 52 is provided at the end on the lower region 16 side.

[0025] The pilot check valve 51 does not obstruct the flow of working fluid when it is supplied from the fluid pump 32 to the lower region 16 of the main cylinder mechanism 10, and restricts the backflow of working fluid from the lower region 16 of the main cylinder mechanism 10. However, since the pilot check valve 51 is designed to open in response to the internal pressure of the third supply and discharge pipe 45, it is configured not to obstruct the flow of working fluid that is pushed back from the lower region 16 to the working fluid tank 33 when working fluid is supplied to the upper region 17 of the main cylinder mechanism 10. The pressure sensor 52 detects the internal pressure in the lower region 16 of the main cylinder mechanism 10 and outputs it to the control unit 90.

[0026] The fifth and sixth supply and discharge pipes 47 and 48 are each provided with tank-side valves 53 and 54, which are shut-off valves. The seventh and eighth supply and discharge pipes 49 and 50 are each provided with main cylinder-side valves 55 and 56, which are shut-off valves. The main cylinder-side valve 55 can switch between a connected state and a disconnected state for the flow of working fluid between the first plunger pump 20A and the lower region 16 of the main cylinder mechanism 10. The main cylinder-side valve 56 can switch between a connected state and a disconnected state for the flow of working fluid between the second plunger pump 20B and the lower region 16 of the main cylinder mechanism 10. These valves 53-56 are opened individually by command from the control unit 90, allowing the working fluid to flow.

[0027] Furthermore, pressure sensors 57 and 58 are provided in the seventh supply / discharge pipe 49 and the eighth supply / discharge pipe 50, respectively, near the first and second cylinders 21A and 21B, rather than the main cylinder side valves 55 and 56. These pressure sensors 57 and 58 individually detect the internal pressure of the first cylinder 21A of the first plunger pump 20A and the internal pressure of the second cylinder 21B of the second plunger pump 20B, and output the results to the control unit 90.

[0028] [Control Unit] The control unit 90 is connected to the servo motors 23A and 23B with gearboxes for the first and second plunger pumps 20A and 20B, the motor 34 for the working fluid tank 33, the first supply valve 41, the second supply valve 42, the tank-side valves 53 and 54, and the main cylinder-side valves 55 and 56, and can control the operation of these components. Furthermore, the control unit 90 is connected to pressure sensors 52, 57, and 58, and acquires the detected pressure inside the lower region 16 of the main cylinder mechanism 10, the first cylinder 21A of the first plunger pump 20A, and the second cylinder 21B of the second plunger pump 20B, where these sensors are located. Furthermore, since the stroke position of the plunger 22 is correlated with the amount of rotation of the output shafts of the servo motors 23A and 23B with reduction gears, the control unit 90 can obtain the stroke position of each plunger 22 from the encoder outputs of the servo motors 23A and 23B with reduction gears of the first and second plunger pumps 20A and 20B. In addition, by determining the stroke position of each plunger 22 from the encoder outputs of the servo motors 23A and 23B with reduction gears of the first and second plunger pumps 20A and 20B, the amount of working fluid supplied and discharged by the first and second plunger pumps 20A and 20B is effectively determined.

[0029] [Main cylinder mechanism drive process] Next, the drive process of the main cylinder mechanism will be described. Hereinafter, when we simply say "delivery of working fluid," we mean the delivery of working fluid from the first plunger pump 20A or the second plunger pump 20B to the main cylinder mechanism 10. Similarly, when we simply say "suction of working fluid," we mean the suction of working fluid from the main cylinder mechanism 10 to the first plunger pump 20A or the second plunger pump 20B.

[0030] Figure 2 shows an example of setting the drive process for the main cylinder mechanism. The control unit 90 drives the main cylinder mechanism 10 according to a preset drive process. In the drive process, as shown in Figure 2, for example, a target pressure and a target time are set for each of the multiple execution steps. An execution step represents a unit of a continuous operation pattern, and represents an operation pattern in which the target pressure is reached at the target time. The drive process is a process in which the operation patterns of the multiple execution steps are executed sequentially in the order of the execution step numbers.

[0031] The operating patterns include pressurizing drive, pressure holding drive, and depressurizing drive of the main cylinder mechanism 10. Pressurizing drive and pressure holding drive are achieved by supplying working fluid. Depressurizing drive is achieved by suction of working fluid. Pressure holding drive is a drive that maintains the applied pressure of the main cylinder mechanism 10, but since working fluid outflow occurs when maintaining the applied pressure, it is necessary to supply working fluid to compensate for this outflow.

[0032] If the amount of working fluid required for pressurized or pressure-holding drive of the main cylinder mechanism 10 exceeds the working fluid capacity of a single plunger pump (20A or 20B), continuous delivery of working fluid using multiple plunger pumps (20A, 20B) is necessary. Similarly, if the amount of working fluid required for depressurized drive of the main cylinder mechanism 10 exceeds the working fluid capacity of a single plunger pump (20A or 20B), continuous suction of working fluid using multiple plunger pumps (20A, 20B) is necessary. Continuous delivery of working fluid and continuous suction of working fluid are achieved as follows.

[0033] [Continuous delivery of working fluid] Figure 3 illustrates an example of continuous pressurization drive of the main cylinder mechanism. In the figure, only a representative pair of first and second plunger pumps 20A and 20B are labeled with reference numerals. The control unit 90 controls the fluid circuit and the first and second plunger pumps 20A and 20B as follows to continuously supply working fluid and realize continuous pressurization drive of the main cylinder mechanism 10.

[0034] Specifically, first, the control unit 90 supplies the working fluid from the tank 33 to the first plunger pump 20A, thereby putting the first plunger pump 20A into a standby state for fluid delivery (timing t1). The standby state for fluid delivery means that a large amount of working fluid is stored in the cylinders of the plunger pump (first cylinder 21A, second cylinder 21B, etc.), and that the system is in a standby state that allows the working fluid to be delivered for a long period of time. Here, the control unit 90 may also put the second plunger pump 20B into a similar standby state (timing t1).

[0035] Then, the control unit 90 causes the working fluid to be delivered from the first plunger pump 20A to the main cylinder mechanism 10 (its lower region 16) (period T1). The delivery of the working fluid causes the main cylinder mechanism 10 to be driven by pressurization or pressure holding.

[0036] Next, when the working fluid in the first plunger pump 20A decreases, the control unit 90 changes the plunger pump supplying working fluid to the main cylinder mechanism 10 from the first plunger pump 20A to the second plunger pump 20B (timing t2). Then, it continues to supply working fluid to the main cylinder mechanism 10 (period T2).

[0037] Prior to this change, the control unit 90 initially closes the tank-side valve 54 and the main cylinder-side valve 56, and then sends working fluid from the second plunger pump 20B to the fluid circuit. After the pressure of the working fluid between the main cylinder-side valve 56 and the second plunger pump 20B increases, the control unit 90 opens the main cylinder-side valve 56. This process reduces the pressure difference of the working fluid, enabling the delivery of working fluid from the second plunger pump 20B to the main cylinder mechanism 10. In this state, the control unit 90 continues to deliver working fluid from the second plunger pump 20B while stopping the delivery of working fluid from the first plunger pump 20A.

[0038] Once the above changes have been made, the control unit 90 then supplies working fluid from the tank 33 to the first plunger pump 20A (period T2a). Before supplying the working fluid, the control unit 90 closes the main cylinder side valve 55 with the tank side valve 53 closed, allowing working fluid to be drawn from the fluid circuit into the first plunger pump 20A. Then, after the pressure of the working fluid between the tank side valve 53 and the first plunger pump 20A has decreased, the control unit 90 opens the tank side valve 53. This process reduces the pressure difference of the working fluid, making it possible to supply working fluid from the tank 33 to the first plunger pump 20A. In this state, the control unit 90 supplies working fluid to the first plunger pump 20A and puts the first plunger pump 20A into a standby state for fluid delivery.

[0039] Then, as described above, when the working fluid in the second plunger pump 20B becomes low, the control unit 90 changes the plunger pump that supplies working fluid to the main cylinder mechanism 10 to the first plunger pump 20A (timing t3). After the change, it supplies working fluid to the second plunger pump 20B, thereby putting the second plunger pump 20B into a standby state for fluid delivery (period T3a).

[0040] By repeatedly performing this control, the working fluid is continuously supplied to the main cylinder mechanism 10, and the main cylinder mechanism 10 can be continuously driven by pressurization or pressure holding.

[0041] [Continuous suction of working fluid] Figure 4 illustrates an example of continuous pressure reduction drive of the main cylinder mechanism. In the figure, only a representative pair of first and second plunger pumps 20A and 20B are labeled with reference numerals. The control unit 90 controls the fluid circuit and the first and second plunger pumps 20A and 20B as follows to continuously draw in working fluid and realize continuous pressure reduction drive of the main cylinder mechanism 10.

[0042] Specifically, first, the control unit 90 discharges the working fluid from the first plunger pump 20A to the tank 33, thereby putting the first plunger pump 20A into a standby state for fluid suction (timing t11). The standby state for fluid suction means that the amount of working fluid in the cylinders of the plunger pump (first cylinder 21A, second cylinder 21B, etc.) is reduced, and it means a standby state that allows the working fluid to be suctioned for a long period of time. Here, the control unit 90 may also put the second plunger pump 20B into a similar standby state (timing t11).

[0043] Then, the control unit 90 causes the working fluid of the main cylinder mechanism 10 (its lower region 16) to be drawn into the first plunger pump 20A (period T11). The main cylinder mechanism 10 is driven to reduce pressure by the suction of the working fluid.

[0044] Next, when the amount of working fluid in the first plunger pump 20A increases, the control unit 90 changes the plunger pump that draws working fluid from the main cylinder mechanism 10 from the first plunger pump 20A to the second plunger pump 20B (timing t12). Then, it continues to draw working fluid from the main cylinder mechanism 10 (period T12).

[0045] During this modification, the control unit 90 initially closes the tank-side valve 54 and the main cylinder-side valve 56, and then sends working fluid from the second plunger pump 20B to the fluid circuit. After the pressure of the working fluid between the main cylinder-side valve 56 and the second plunger pump 20B increases, the control unit 90 opens the main cylinder-side valve 56. This process reduces the pressure difference of the working fluid, making it possible to draw working fluid from the main cylinder mechanism 10 to the second plunger pump 20B. In this state, the control unit 90 allows working fluid to be drawn from the main cylinder mechanism 10 to the second plunger pump 20B, while stopping the suction of working fluid from the main cylinder mechanism 10 by the first plunger pump 20A.

[0046] Once the above changes have been made, the control unit 90 then discharges the working fluid from the first plunger pump 20A to the tank 33 (period T12a). Before discharging the working fluid, the control unit 90 closes the main cylinder side valve 55 with the tank side valve 53 closed, allowing the working fluid to be drawn into the first plunger pump 20A from the fluid circuit. Then, after the pressure of the working fluid between the tank side valve 53 and the first plunger pump 20A has decreased, the control unit 90 opens the tank side valve 53. This process reduces the pressure difference of the working fluid, making it possible to discharge the working fluid from the first plunger pump 20A to the tank 33. In this state, the control unit 90 discharges the working fluid from the first plunger pump 20A, putting the first plunger pump 20A into a standby state for fluid suction (period T12a).

[0047] Then, as described above, when the amount of working fluid in the second plunger pump 20B increases, the control unit 90 changes the plunger pump that draws working fluid from the main cylinder mechanism 10 to the first plunger pump 20A (timing t13). After the change, it discharges the working fluid from the second plunger pump 20B and puts the second plunger pump 20B into a standby state for fluid suction (period T13a).

[0048] By repeatedly performing this control, the working fluid is continuously drawn out of the main cylinder mechanism 10, and the main cylinder mechanism 10 can be continuously driven under reduced pressure.

[0049] [Switching the operating pattern of the main cylinder mechanism] The drive process of the main cylinder mechanism 10 includes a switching of operation patterns, from a pressurizing drive or pressure-holding drive that requires the delivery of working fluid to a depressurizing drive that requires the suction of working fluid. Similarly, the drive process of the main cylinder mechanism 10 includes a switching of operation patterns, from a depressurizing drive that requires the suction of working fluid to a pressurizing drive or pressure-holding drive that requires the delivery of working fluid.

[0050] First, let's explain the operation of the pressurizing device of the comparative example. When switching from a drive that requires the delivery of working fluid to a drive that requires the suction of working fluid, it is possible that the first plunger pump 20A has delivered only a small amount of working fluid before the switch, and the second plunger pump 20B has entered a standby state for fluid delivery. In such a case, a large amount of working fluid accumulates in both the first plunger pump 20A and the second plunger pump 20B, and it becomes impossible to draw in a large amount of working fluid from either. Therefore, after the operation pattern switches, it may be necessary to temporarily stop the drive of the main cylinder mechanism 10 and discharge the working fluid from the first plunger pump 20A and the second plunger pump 20B to the tank 33.

[0051] Similarly, in the comparative example pressurizing device, when switching from a drive requiring the suction of working fluid to a drive requiring the discharge of working fluid, it is possible that the first plunger pump 20A has only drawn in a small amount of working fluid before the switch, and the second plunger pump 20B has entered a standby state for fluid suction. In such a case, after the switch, both the first plunger pump 20A and the second plunger pump 20B will have a small amount of working fluid, and neither can discharge a large amount of working fluid. Therefore, after the operation pattern switches, it may be necessary to temporarily stop the drive of the main cylinder mechanism 10 and supply working fluid to the first plunger pump 20A and the second plunger pump 20B from the tank 33.

[0052] In the pressurizing device 1 of this embodiment, the need to temporarily stop the operation of the main cylinder mechanism 10, as described above, is reduced by performing a preparatory operation, as described later, when the operation pattern is switched.

[0053] The control unit 90 monitors the pressure of the main cylinder mechanism 10 and adjusts the amount of working fluid discharged or suctioned so that operation corresponding to the drive process setting (Figure 2) is obtained. In this control, the total amount of working fluid discharged or suctioned required to achieve the target pressure is often not fixed at a constant value, and variations occur in the optimal amount of working fluid discharged or suctioned. Therefore, it is difficult to predict in advance how much working fluid remains in the first and second plunger pumps 20A and 20B at the timing when the operation pattern of the main cylinder mechanism 10 switches.

[0054] [Preparatory actions before switching operation patterns] Figure 5 illustrates the preparatory operation before switching the operating pattern. Below, we will describe the case in which the preparatory operation of the second plunger pump 20B is performed while the first plunger pump 20A is supplying or drawing working fluid to and from the main cylinder mechanism 10. The reverse case is also described.

[0055] The control unit 90 of the pressurizing device 1 in this embodiment, based on the switching timings t31 and t32 when the operation pattern of the main cylinder mechanism 10 switches from the first operation pattern to the second operation pattern, performs preparatory operations (T21, T22) corresponding to the operation pattern after the switch, prior to the switching timings t31 and t32, on the plunger pumps 20A and 20B, which are the first and second plunger pumps that do not exchange working fluid with the main cylinder mechanism 10 in the first operation pattern. Here, the first operation pattern and the second operation pattern are specifically the pressurizing drive of the main cylinder mechanism 10 (corresponding to the first operation pattern) and the depressurizing drive of the main cylinder mechanism 10 (corresponding to the second operation pattern). Alternatively, the first and second operating patterns may be a pressure-holding drive of the main cylinder mechanism 10 (corresponding to the first operating pattern) and a pressure-reducing drive of the main cylinder mechanism 10 (corresponding to the second operating pattern), or a pressure-reducing drive of the main cylinder mechanism 10 (corresponding to the first operating pattern) and a pressure-pressure drive of the main cylinder mechanism 10 (corresponding to the second operating pattern), or a pressure-reducing drive of the main cylinder mechanism 10 (corresponding to the first operating pattern) and a pressure-holding drive of the main cylinder mechanism 10 (corresponding to the second operating pattern).

[0056] The preparation operation will differ depending on the operation pattern of the main cylinder mechanism 10 after the switch ("pressure reduction" or "pressure reduction, pressure holding"). When the operation pattern of the main cylinder mechanism 10 switches from the "pressure reduction (or pressure holding)" operation pattern, which requires the delivery of working fluid, to the "pressure reduction" operation pattern, which requires the suction of working fluid, the preparation operation (T21) is an operation to reduce (discharge) the working fluid of the second plunger pump 20B, as shown in Figure 5(A).

[0057] Conversely, when the operation pattern of the main cylinder mechanism 10 switches from a "depressurization" operation pattern that requires the suction of working fluid to a "pressurization (or pressure holding)" operation pattern that requires the discharge of working fluid, the preparation operation (T22) is an operation that increases (supplies) the working fluid of the second plunger pump 20B, as shown in Figure 5(B).

[0058] The start timings t21 and t22 of the preparation operation are set to a timing equal to or earlier than the preparation time T21 and T22 from the switching timings t31 and t32. Here, timing is defined not as being limited to a precise single point in time, but including cases where there is an error of ±10%. That is, if the time from the start timings t21 and t22 to the switching timings t31 and t32 is 90% or more and 110% or less of the preparation time T21 and T22, it can be considered to be the timing described above. Furthermore, the time length from the start timings t21 and t22 to the switching timings t31 and t32 may be longer than the preparation time T21 and T22. By setting the start timings t21 and t22 of the preparation operation in this way, the second plunger pump 20B can be set to the amount of working fluid accumulated corresponding to the operation pattern after the switch at the switching timings t31 and t32 of the operation pattern of the main cylinder mechanism 10. Furthermore, it is possible to reduce the likelihood of the working fluid in the first plunger pump 20A running out or becoming full between the start timings t21 and t22 of the preparation operation and the switching timings t31 and t32, which could hinder the continued operation of the main cylinder mechanism 10.

[0059] [Position of the plunger in a plunger pump] Figure 6 illustrates the positions of the plungers in the first and second plunger pumps 20A and 20B. As shown in Figure 6, the plunger 22 of the first and second plunger pumps 20A and 20B is positioned at the suction end p1, the point just before the suction end p2, the discharge end p3, and the point just before the discharge end p4.

[0060] The suction end p1 is the position when the working fluid has been completely drawn in. The discharge end p3 is the position when the working fluid has been completely discharged. The position just before the suction end p2 is the position where a suction area C1 remains in the first cylinder 21A that allows for the drawing in of an additional amount of working fluid beyond the suction end p1. The position just before the discharge end p4 is the position where a discharge area C2 remains in the first cylinder 21A that allows for the discharge of an additional amount of working fluid beyond the discharge end p3.

[0061] The control unit 90 can identify that the plunger 22 has reached at least the point p2 just before the suction end and the point p4 just before the discharge end. This identification can be performed based on information about the amount of rotation of the servo motor 23A, or it can be performed based on the output of a sensor that separately detects the position of the plunger 22. The control unit 90 may be configured to determine the timings t2 and t3 in the pressurizing drive shown in Figure 3, or the timings t12 and t13 in the depressurizing drive shown in Figure 4, based on the trigger that the plunger 22 has reached p4 just before the discharge end, or p2 just before the suction end. That is, during continuous pressurizing drive, if the plunger 22 of the plunger pump (20A or 20B) that is discharging the working fluid reaches p4 just before the discharge end, the control unit 90 changes the plunger pump discharging the working fluid from the first plunger pump 20A to the second plunger pump 20B, or vice versa. Also, during continuous depressurizing drive, if the plunger 22 of the plunger pump (20A or 20B) that is drawing in the working fluid reaches p2 just before the suction end, the control unit 90 changes the plunger pump drawing in the working fluid from the first plunger pump 20A to the second plunger pump 20B, or vice versa.

[0062] Furthermore, the standby state in pressurized drive shown in Figure 3, or the standby state in depressurized drive shown in Figure 4, may be controlled to a state in which the plunger 22 is positioned at p2 just before the suction end, or at p4 just before the discharge end.

[0063] The suction remaining area C1 may be set to a capacity that can withstand the suction of the working fluid for the preparation time T22 shown in Figure 5(B). That is, even if the first plunger pump 20A is at p2 just before the suction end at timing t22, the capacity may be set so that the suction of the working fluid for the preparation time T22 can continue due to the suction remaining area C1. This capacity will vary depending on the depressurization rate of the main cylinder mechanism 10, but the capacity of the suction remaining area C1 may be set so that it can withstand the maximum depressurization rate or the maximum depressurization rate in a range excluding extremely fast depressurization rates.

[0064] The remaining discharge area C2 may be set to a capacity that can accommodate the discharge of working fluid for the preparation time T21 shown in Figure 5(A). That is, even if the first plunger pump 20A is at p4 just before the discharge end at timing t21, the capacity may be set so that the working fluid in the remaining discharge area C2 can continue to discharge the working fluid for the preparation time T21. This capacity will vary depending on the pressurization speed of the main cylinder mechanism 10, but the capacity of the remaining discharge area C2 may be set to accommodate the maximum pressurization speed or the maximum pressurization speed in a range excluding extremely fast pressurization speeds.

[0065] [Preparation actions before switching operation patterns and the movement speed of plunger 22] The preparation operation (T21) in Figure 5(A) corresponds to moving the plunger 22 of the second plunger pump 20B to p4 just before the discharge end, while the working fluid is ready to be discharged into the tank 33.

[0066] The preparation operation (T22) in Figure 5(B) corresponds to moving the plunger 22 of the second plunger pump 20B to p2 just before the suction end, while the working fluid is being supplied from the tank 33.

[0067] In the above preparation operation, the situation in which the plunger 22 moves the most is when the second plunger pump 20B changes from a standby state for depressurization drive (see Figure 4) to a standby state for pressurization drive (see Figure 3), or vice versa. That is, when the plunger 22 is moved from p2 just before the suction end to p4 just before the discharge end, or vice versa. The length of this movement is the stroke length L of the effective range of motion (Figure 6).

[0068] The first plunger pump 20A can move the plunger 22 at a predetermined speed V when working fluid is supplied from the tank 33 and when working fluid is discharged to the tank 33.

[0069] Therefore, the preparation time T21 required to move the plunger 22 from p2 before the suction end to p4 before the discharge end and discharge the working fluid into the tank 33 is "L / V". Similarly, the preparation time T22 required to move the plunger 22 from p4 before the discharge end to p2 before the suction end and supply the working fluid from the tank 33 is "L / V".

[0070] [Control Processing] Next, the control process of the main cylinder mechanism 10 executed by the control unit will be described. Figures 7 and 8 are flowcharts of the said control process. In the following description, of the first and second plunger pumps 20A and 20B, the one that exchanges working fluid with (sends out or sucks in) the main cylinder mechanism 10 will be referred to as the "operating pump," and the one that does not exchange working fluid with the main cylinder mechanism 10 will be referred to as the "standby pump."

[0071] When the control process starts, the control unit 90 determines whether the drive type currently required is a pressurized drive (including a pressure-holding drive) or a depressurized drive based on the drive process setting data (step S1). If it is a pressurized drive, the control unit 90 sends working fluid from the active plunger pump (step S2), and in parallel, puts the standby pump into standby mode (drive stopped) (step S3). Next, the control unit 90 determines whether it is the start timing t21 of the preparation operation before switching the operation pattern (Figure 5(A)) (step S4). If it is NO, it determines whether the plunger 22 of the active pump has reached p4 just before the discharge end (step S5). If the result of step S5 is NO, the control unit 90 returns to the processing in steps S2 and S3.

[0072] If the result of step S5 is YES, the control unit 90 changes the standby pump to the active pump and changes the active pump to the standby pump (steps S6, S7). This change is achieved by controlling the opening and closing of the tank-side valves 53, 54 and the main cylinder-side valves 55, 56 as described above. The control unit 90 then continues to supply the working fluid using the changed active pump (step S2). Furthermore, in parallel with step S2, the control unit 90 supplies working fluid to the standby pump by moving the plunger 22 of the standby pump to just before the suction end, and puts the standby pump into a standby state for pressurized drive (step S8). The standby pump is then put into a standby state (step S3).

[0073] On the other hand, if the determination in step S4 is YES, the control unit 90 determines whether the plunger of the standby pump is closer to the discharge end p3 than to the discharge end p4 (step S9). If YES, the standby pump is put into standby mode (step S3). On the other hand, if NO, the working fluid is discharged from the standby pump to the tank 33, and the plunger is positioned at the discharge end p4 (step S10). The standby pump is then put into standby mode (step S3). The processing in steps S4, S9, and S10 realizes the preparatory operation before switching the operation pattern described above (Figure 5(A)).

[0074] Therefore, when the determination result in step S1 is for reduced pressure drive, it is avoided that both the active pump and the standby pump become full of working fluid, allowing for a quick switch to reduced pressure drive, and then the reduced pressure drive can be continued thereafter.

[0075] The processes in steps S12 to S20 are the same as those in steps S2 to S10, but reversed from pressurized drive to depressurized drive. In other words, if you read the explanation of the processes in steps S2 to S10 as reversing pressurization and depressurization, reversing the suction and discharge of the working fluid, and reversing the point just before the suction end p2 and the point just before the discharge end p4, you will get the explanation of the processes in steps S12 to S20.

[0076] [Example of pressurizing device operation] Figure 9 is a timing chart showing an example of the operation of the pressurizing device. In Figure 9, "pressure" refers to the pressure in the main cylinder mechanism 10, and the lower section shows the state of the first plunger pumps 20A and 20B. In the figure, only a representative pair of first and second plunger pumps 20A and 20B are labeled with symbols. In addition, a black circle is placed next to the pump designated as the "operating pump" among the first and second plunger pumps 20A and 20B.

[0077] According to the pressurizing device 1 of this embodiment, the control processing shown in Figures 7 and 8 enables the operation shown in Figure 9. That is, during periods such as T51-T54 and T56, when driving (pressurizing drive and pressure holding drive) requiring the delivery of working fluid continues, the process of continuously delivering working fluid is performed by alternately switching between the working pump and the standby pump, with one of the first and second plunger pumps 20A and 20B being the active pump and the other being the standby pump.

[0078] Furthermore, during periods such as T55 and T57, when depressurization driving requiring the suction of working fluid continues, one of the first and second plunger pumps 20A and 20B is designated as the active pump and the other as the standby pump, and the working fluid is continuously suctioned by alternately switching between the active pump and the standby pump.

[0079] Furthermore, at the switching timings t61, t62, and t63 for the operation pattern from a drive requiring the delivery of working fluid to a drive requiring suction, the standby pump performs preparatory operations J61, J62, and J63 corresponding to the operation pattern after the switch during the preparation period T61, T62, and T63 prior to each of the timings t61, t62, and t63.

[0080] Therefore, near the switching timings t61 and t63, it is suppressed that a large amount of working fluid accumulates in both the first and second plunger pumps 20A and 20B, even though subsequent suction of working fluid is required. Similarly, near the switching timing t62, it is suppressed that a large amount of working fluid does not accumulate in both the first and second plunger pumps 20A and 20B, even though subsequent discharge of working fluid is required. Therefore, continuous operation of the main cylinder mechanism 10 can be achieved even when the operating pattern is switched.

[0081] [Effects of the Embodiment] As described above, according to the pressurizing device 1 of this embodiment, the control unit 90 causes the standby pump of the first and second plunger pumps 20A and 20B to perform preparatory operations corresponding to the operation pattern after the switch, based on the switching timings t61, t62, and t63 of the operation pattern of the main cylinder mechanism 10, before the switching timings t61, t62, and t63. Therefore, even when switching the operation pattern from a drive that requires the delivery of working fluid to a drive that requires suction, it is possible to suppress interference with the continuous driving of the main cylinder mechanism 10.

[0082] Furthermore, according to the pressurizing device 1 of this embodiment, the positions of the plungers 22 in the first and second plunger pumps 20A and 20B include p2 (discharge preparation complete position) just before the suction end where preparation for discharging the working fluid is complete, and p4 (suction preparation complete position) just before the discharge end where preparation for suctioning the working fluid is complete. In addition, preparation times T21 and T22 are required to change the plunger 22 from p2 just before the suction end to p4 just before the discharge end, or vice versa. The control unit 90 starts the preparation operation of the standby pump at least the preparation times T21 and T22 (Figures 5(A) and 5(B)) before the switching timings t61, t62, and t63. Therefore, the standby pump can be changed to a prepared state corresponding to the operation pattern after switching by the switching timings t61, t62, and t63.

[0083] Furthermore, according to the pressurizing device 1 of this embodiment, the positions of the plungers 22 in the first and second plunger pumps 20A and 20B include the discharge end p3 where the working fluid has been completely discharged, the suction end p1 where the working fluid has been completely drawn in, the point just before the discharge end p4 which is before the discharge end p3, and the point just before the suction end p2 which is before the suction end p1. The control unit 90 then sets the point when the plunger 22 reaches the point just before the discharge end p4 or the point just before the suction end p2 as the first change condition during periods when the switching timings t61, t62, and t63 are not included, and based on this first change condition, changes one plunger pump from the active pump to the standby pump, and changes the other plunger pump from the standby pump to the active pump. Therefore, even immediately before being changed to the standby pump, the first and second plunger pumps 20A and 20B still have the capacity to draw in or discharge working fluid. Therefore, even if the pump on the user side reaches the point just before the discharge end p4 or just before the suction end p2 during the preparation period T61, T62, and T63 before the operation pattern switching of the main cylinder mechanism 10, the operation of the main cylinder mechanism 10 can be continued by using the remaining working fluid.

[0084] Specifically, during the preparation period T61, T62, and T63 prior to the switching timings t61, t62, and t63, the control unit 90 should be controlled to exclude the first change condition described above from the conditions for changing between the standby pump and the active pump. This type of control makes it possible to achieve control using the excess working fluid (control that continues to drive the main cylinder mechanism 10).

[0085] Embodiments of the present invention have been described above. However, the present invention is not limited to the embodiments described above. For example, the configuration of the main cylinder mechanism, fluid circuit, and plunger pump is not limited to the specific examples shown, and various types of configurations may be adopted. Also, the number of plunger pumps is not limited to the two first and second plunger pumps 20A and 20B, but may be three or more. Furthermore, details shown in the embodiments can be modified as appropriate without departing from the spirit of the invention. [Explanation of Symbols]

[0086] 1. Pressurizing device 10 Main Cylinder Mechanism 20A No. 1 Plunger Pump 20B Second Plunger Pump 90 Control Unit p1 Suction end p2 Just before the suction end (discharge ready position) p3 sending end p4 Just before the discharge end (suction ready position) T21, T22 Preparation time required t61~t63 switching timing T61~T63 Preparation period

Claims

1. Multiple plunger pumps, A main cylinder mechanism connected to the plurality of plunger pumps so as to be able to deliver and draw in working fluid, Equipped with, Based on the switching timing at which the operating pattern of the main cylinder mechanism switches from a first operating pattern to a second operating pattern, before the switching timing, the plunger pumps among the plurality of plunger pumps that do not exchange working fluid with the main cylinder mechanism in the first operating pattern perform a preparatory operation corresponding to the second operating pattern. The plunger pump requires preparation time to change the position of the plunger between the ready-to-dispense position and the ready-to-suction position. In the first operating pattern, a plunger pump that does not exchange working fluid with the main cylinder mechanism starts the preparation operation earlier than the preparation time from the switching timing. Pressurizing device.

2. The aforementioned switching timing includes the timing of switching from an operation pattern that delivers working fluid to the main cylinder mechanism to an operation pattern that draws working fluid from the main cylinder mechanism, and the timing of switching from an operation pattern that draws working fluid to the main cylinder mechanism to an operation pattern that delivers working fluid from the main cylinder mechanism. The pressurizing device according to claim 1.

3. When switching from an operation pattern that supplies working fluid to the main cylinder mechanism to an operation pattern that draws working fluid from the main cylinder mechanism, the preparatory operation is an operation that reduces the working fluid of the plunger pump. The pressurizing device according to claim 1.

4. When switching from an operation pattern of drawing working fluid from the main cylinder mechanism to an operation pattern of supplying working fluid to the main cylinder mechanism, the preparation operation is an operation of increasing the working fluid of the plunger pump. The pressurizing device according to claim 1.

5. The plunger positions in the aforementioned plurality of plunger pumps include the discharge end where the working fluid has been completely discharged, the suction end where the working fluid has been completely drawn in, the point just before the discharge end, and the point just before the suction end. If there is no switching timing, when the plunger reaches just before the discharge end or just before the suction end, the plunger pump that exchanges working fluid with the main cylinder mechanism is changed to another plunger pump. The pressurizing device according to claim 1.

6. During the period in which the preparation operation is performed prior to the switching timing, when the plunger in the plunger pump reaches just before the discharge end or just before the suction end, the plunger pump that exchanges working fluid with the main cylinder mechanism is not changed to another plunger pump. The pressurizing device according to claim 5.

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