Pumping device

Abstract

To provide a pump system that reduces energy loss.SOLUTION: The pump system comprises: a pump part that ejects coating liquid; a motor to be driven by electricity; a pressure adjustment part that adjusts the pressure of compressed-air to be provided from an outside compressed-air supply source and ejects the compressed-air; a driving device that provides a driving force to the pump part; and a control part that switches the driving mode between a first mode that drives the motor and a second mode that drives the pressure adjustment part to control the ejection of the coating liquid from the pump part. The control part sets the driving mode to the first mode when the coating liquid is ejected from the pump part and to the second mode when the coating liquid is not ejected from the pump part.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to a pump device.

Background Art

[0002] For example, a plunger pump used as a pump device is known in pneumatic type using compressed air as a driving source and electric type using an electric motor as a driving source. In recent years, for the purpose of reducing carbon dioxide emissions, replacement from pneumatic type to electric type with superior energy efficiency during operation has been attracting attention. By the way, depending on the working conditions such as setup work such as loading or transporting workpieces or curing, the plunger pump may be waiting for a long time in a state of being constantly pressurized. The pneumatic type is inferior in energy efficiency during operation compared to the electric type, while it is superior in energy efficiency during standby. Therefore, depending on the driving situation of the plunger pump, both the pneumatic type and the electric type may reduce energy efficiency.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention has been made in view of the above circumstances, and an object thereof is to provide a pump device capable of suppressing energy loss.

Means for Solving the Problems

[0005] The pump device of the embodiment includes a pump unit capable of discharging a coating liquid, a motor driven by electric power, and a pressure adjustment unit that adjusts the pressure of compressed air supplied from an external compressed air supply source and discharges it; a drive device that supplies driving force to the pump unit; and a control unit that controls the discharge of the coating liquid from the pump unit by switching between a first drive method for driving the motor and a second drive method for driving the pressure adjustment unit. The control unit sets the drive method to the first method when the coating liquid is discharged from the pump unit, and sets the drive method to the second method when the coating liquid is not discharged from the pump unit. [Brief explanation of the drawing]

[0006] [Figure 1] This diagram schematically shows an example of the electrical configuration of a pump system using a plunger pump according to one embodiment. [Figure 2] This figure shows an example of the control content of the control unit in the coating process according to one embodiment. [Modes for carrying out the invention]

[0007] Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, the terms "first" and "second" attached to the components are simply for distinguishing similar components and do not imply any superiority or inferiority between components or any temporal elements.

[0008] The plunger pump 10 in this embodiment is composed of a plunger pump. The pump device is not limited to a plunger pump, but may also be a diaphragm pump, bellows pump, etc. The plunger pump 10 can be used, for example, in airless painting, which pressurizes and atomizes relatively high viscosity coating liquids such as paint. The plunger pump 10 is configured to be movable within a factory or other work site by being fixed to a trolley (not shown). The plunger pump 10 is not limited to being fixed to a trolley, but may also be fixed to a steel frame, wall, etc.

[0009] As shown in Figure 1, the plunger pump 10 comprises a drive unit 20, a pump unit 30, and a control unit 40. The drive unit 20 and the control unit 40 are housed in, for example, an explosion-proof enclosure 11. The drive unit 20 functions as the drive source for the plunger pump 10, that is, it supplies driving force to the pump unit 30. The drive unit 20 includes an air drive unit 21, an electric drive unit 22, a case 23, a piston 24, and a rod 25. The air drive unit 21 is connected to a compressed air supply source 51, such as a compressor, and generates driving force using air compressed by the compressed air supply source 51.

[0010] The air-driven unit 21 includes a pressure adjustment unit 211, a pressure measuring unit 212, and a control valve 213. The pressure adjustment unit 211 is located between the compressed air supply source 51 and the control valve 213. The pressure adjustment unit 211 is composed of, for example, an electro-pneumatic regulator and has the function of adjusting the pressure of the compressed air supplied from the compressed air supply source 51 and discharging it. The pressure measuring unit 212 is composed of, for example, a pressure sensor and is built into the pressure adjustment unit 211. The pressure measuring unit 212 has the function of measuring the pressure of the compressed air discharged from the pressure adjustment unit 211.

[0011] The control valve 213 is located between the pressure regulating unit 211 and the case 23. The control valve 213 is, for example, a five-way solenoid valve and is used to control the supply and discharge of compressed air to and from the case 23. The downstream side of the control valve 213 is connected to an upper port (not shown) on the top of the case 23 and a lower port (not shown) on the bottom of the case 23.

[0012] The electric drive unit 22 comprises a motor 221 and a current detection unit 222. The motor 221 is driven by power supplied from an external power source, such as a commercial power supply or battery power. The motor 221 is composed of, for example, a stepping motor or a brushless motor, and is connected to the rod 25 via gears (not shown). The current detection unit 222 detects the current flowing through the motor 221. The current detection unit 222 is composed of, for example, a current sensor.

[0013] The case 23 is made of, for example, steel and is formed in a cylindrical shape. The piston 24 and part of the rod 25 are housed within the case 23. The piston 24 is configured, for example, in a disc shape. The piston 24 is able to reciprocate vertically within the case 23 by alternately supplying and discharging compressed air to the space above and below the piston 24 through the upper and lower ports of the case 23. The rod 25 is connected to the piston 24 and is able to reciprocate vertically integrally with the piston 24. The rod 25 is connected to, for example, an electric drive unit 22 and is able to reciprocate vertically within the case 23 by receiving driving force supplied from the electric drive unit 22. The lower end of the rod 25 protrudes downward from the case 23.

[0014] The pump unit 30 has the function of sucking up the coating liquid stored in, for example, the tank 52 and discharging the sucked coating liquid at a predetermined discharge pressure. The predetermined discharge pressure means a high pressure of, for example, 5 to 15 MPa. The pump unit 30 can be configured to have a pump case 31 and a plunger 32. The pump case 31 is made of, for example, steel and is formed in a cylindrical shape, and constitutes the outer shell of the pump unit 30.

[0015] The pump case 31 has a suction port 311 and a discharge port 312. The suction port 311 has the function of drawing the coating liquid stored in the tank 52 into the pump case 31. The suction port 311 is located at the bottom of the pump case 31 and is connected to the tank 52 via, for example, a flexible suction hose 53. The suction port 311 is provided with a suction valve (not shown). The suction valve has a check valve function that allows the coating liquid to pass from the outside of the pump case 31 to the inside of the pump case 31, but blocks the coating liquid from passing from the inside of the pump case 31 to the outside of the pump case 31.

[0016] The discharge port 312 has the function of discharging the coating liquid supplied into the pump case 31 to the outside of the pump case 31. The discharge port 312 is provided on the side of the pump case 31 and is connected to the spray gun 91 via, for example, a pressure-resistant paint hose 54. The operator applies the coating liquid supplied into the pump case 31 to the object to be coated by operating the spray gun 91. In addition, a check valve (not shown) is provided downstream of the discharge port 312 to prevent the coating liquid discharged from the discharge port 312 from flowing back into the space inside the pump case 31.

[0017] The plunger 32 has its lower portion housed within the pump case 31 and its upper portion protruding from within the pump case 31, and is configured to reciprocate in a linear direction, i.e., vertically. The upper end of the plunger 32 is detachably connected to the lower end of the rod 25 via a connecting member (not shown), such as a nut. In this case, the upper end of the plunger 32 and the lower end of the rod 25 are, for example, threaded. In this way, the plunger 32 is driven by the air drive unit 21 and the electric drive unit 22, that is, it reciprocates vertically in conjunction with the reciprocating movement of the rod 25. The pump unit 30 then repeatedly and continuously sucks up and discharges the coating liquid as the plunger 32 reciprocates vertically.

[0018] The control unit 40 is mainly composed of a microcomputer having memory areas such as a CPU (not shown), ROM, RAM, and rewritable flash memory, and is responsible for controlling the entire plunger pump 10. The control unit 40 is electrically connected to the pressure adjustment unit 211, the pressure measurement unit 212, the control valve 213, the motor 221, and the current detection unit 222. The control unit 40 performs various controls and processes related to the plunger pump 10 by executing programs stored in its memory area.

[0019] The control unit 40 controls the discharge of the coating liquid from the pump unit 30 by controlling the drive of the pressure adjustment unit 211, the control valve 213, and the motor 221 based on the pressure measured by the pressure measuring unit 212 and the current detected by the current detection unit 222. In this embodiment, the control unit 40 is configured to switch between multiple drive methods. That is, the control unit 40 can switch between a first method of driving the motor 221 and a second method of driving the pressure adjustment unit 211.

[0020] The control unit 40 can set the drive mode to the first mode when coating liquid is discharged from the pump unit 30. On the other hand, the control unit 40 can set the drive mode to the second mode when coating liquid is not discharged from the pump unit 30. The control unit 40 can switch the drive mode depending on the operating status of the pump unit 30, i.e., the plunger pump 10. Furthermore, the control unit 40 can switch the drive mode from the first mode to the second mode if the coating liquid is not discharged from the pump unit 30 for a predetermined period of time while the drive mode is set to the first mode. In addition, the control unit 40 can switch the drive mode from the second mode to the first mode if the pressure of the compressed air measured by the pressure measuring unit 212 changes while the drive mode is set to the second mode.

[0021] Next, with reference to Figure 2, an example of the control content performed by the control unit 40 in the coating process will be explained. Graph (a) in Figure 2 shows the operation of the spray gun 91 in the coating process, i.e., the ON-OFF transition of the spray. Graph (b) in Figure 2 shows the transition of the current output value of the motor 221, i.e., the measured value of the current detection unit 222. Graph (c) in Figure 2 shows the transition of the pressure output value of the pressure adjustment unit 211, i.e., the measured value of the pressure measurement unit 212. The coating process also alternates between a first period T1 and a second period T2. The first period T1 is the period during which the drive method is set to the first method by the control unit 40. The second period T2 is the period during which the drive method is set to the second method by the control unit 40.

[0022] In the case of the example of FIG. 2, when the power supply to the plunger pump 10 is turned on, the control unit 40 outputs a standby current I0 to the motor 221. The standby current I0 corresponds to the hydraulic pressure sufficient to maintain the position of the piston 24. By supplying the standby current I0 in this way, it is possible to prevent the motor 221 from rotating in the reverse direction due to the hydraulic pressure in the pump unit 30. Next, as shown in the arrow A1 portion of FIG. 2, when the spray is turned on, the control unit 40 switches the standby current I0 and outputs a drive current I1 to the motor 221.

[0023] Thereafter, as shown in the arrow A2 portion of FIG. 2, when the spray is turned off, the control unit 40 stops the supply of the drive current I1 and outputs the standby current I0 to the motor 221. Then, the control unit 40 switches and outputs the standby current I0 and the drive current I1 according to the ON-OFF switching of the spray. The determination of the ON-OFF of the spray can be performed based on, for example, the change in the measured value of the current detection unit 222.

[0024] As shown in the arrow A3 portion of FIG. 2, when the spray has been turned off and the spray has not been turned on for a predetermined period t, for example, 5 minutes, the control unit 40 stops the supply of current to the motor 221 and controls the air drive unit 21 to supply a standby pressure P corresponding to the magnitude of the standby current I0 into the case 23. In this way, when the predetermined period t has elapsed after the spray has been turned off and the pump unit 30 is in the standby state, the control unit 40 switches the drive method from the first method to the second method. Thereby, while stopping the drive of the electric drive unit 22 and suppressing power consumption, it is possible to maintain the standby state of the pump unit 30 by the air pressure supplied from the air drive unit 21.

[0025] Subsequently, as shown by arrow A4 in Figure 2, when the spray is turned ON and the pump unit 30 is restarted, the control unit 40 controls the air drive unit 21 to discharge the compressed air that was used during standby from inside the case 23 and outputs a drive current I1 to the motor 221. At this time, when the spray is turned ON while compressed air is supplied into the case 23 from the air drive unit 21, the pressure of the compressed air measured by the pressure measuring unit 212 decreases, as shown by arrow B1 in Figure 2. In other words, the control unit 40 can determine that the pump unit 30 has restarted from standby based on the measurement result of the pressure measuring unit 212. When the pump unit 30 restarts from standby, the control unit 40 switches the drive method from the second method to the first method. In this way, the control unit 40 can execute the coating process by switching the drive method between the first method and the second method according to the driving status of the pump unit 30, i.e., the plunger pump 10.

[0026] Here, for example, if the plunger pump 10 is configured to have only the air-driven unit 21 out of the air-driven unit 21 and the electric-driven unit 22, when the spray is turned ON, the pressure balance between the case 23 and the pump unit 30 will be disrupted, and compressed air will be supplied by the air-driven unit 21 to compensate for this imbalance. However, since the supply of compressed air by the air-driven unit 21 takes time, the liquid pressure inside the pump unit 30 may decrease.

[0027] On the other hand, if the system is configured to only include an electric drive unit 22, when the spray is turned ON, the load current of the motor 221 decreases. Therefore, it is conceivable to supply current to the motor 221 to compensate for this decrease and suppress the drop in hydraulic pressure in the pump unit 30. However, the current supplied to the motor 221 must be limited from the standpoint of avoiding risks such as motor burnout. As a result, the current supplied to the motor 221 when the spray is ON is limited, which may lead to a drop in hydraulic pressure in the pump unit 30.

[0028] Therefore, the plunger pump 10 of this embodiment is configured to include an air drive unit 21 and an electric drive unit 22. This allows the compressed air from the air drive unit 21 to be used at the moment the pump unit 30 is restarted to compensate for the current that is limited to the motor 221. As a result, compared to a configuration in which the plunger pump 10 is equipped with only one of the air drive unit 21 or the electric drive unit 22, the drop in liquid pressure in the pump unit 30 when spraying is turned ON can be suppressed.

[0029] According to the embodiment described above, the plunger pump 10 comprises a pump unit 30, a drive unit 20, and a control unit 40. The pump unit 30 is capable of discharging a coating liquid. The drive unit 20 supplies driving force to the pump unit 30. The drive unit 20 has a motor 221 and a pressure adjustment unit 211. The motor 221 is driven by electric power. The pressure adjustment unit 211 adjusts the pressure of compressed air supplied from an external compressed air supply source 51 and discharges it. The control unit 40 controls the discharge of the coating liquid from the pump unit 30 by switching between a first drive mode that drives the motor 221 and a second drive mode that drives the pressure adjustment unit 211. The control unit 40 sets the drive mode to the first mode when the coating liquid is discharged from the pump unit 30, and sets the drive mode to the second mode when the coating liquid is not discharged from the pump unit 30.

[0030] Here, for example, if the discharge of the coating liquid from the pump unit 30 is controlled solely by the motor 221, it is necessary to supply a standby current to the pump unit 30 to provide a constant driving force even when the pump unit 30 is not discharging the coating liquid, i.e., when the plunger pump 10 is in standby mode. Therefore, power is consumed when the plunger pump 10 is in standby mode. To address this, when the pump unit 30 is in standby mode and not discharging the coating liquid, the drive method is switched from the first method to the second method, stopping the motor 221 and driving the pressure adjustment unit 211 to supply air pressure equivalent to the standby current to the pump unit 30, thereby reducing power consumption. This reduces energy loss. As a result, it is possible to reduce carbon dioxide emissions and lower the environmental burden.

[0031] Furthermore, the control unit 40 switches the drive mode from the first mode to the second mode if no coating liquid is discharged from the pump unit 30 for a predetermined period of time while the drive mode is set to the first mode. This allows for further reduction of energy loss, for example, when the pump unit 30 is operated intermittently, by maintaining the drive mode in the first mode and operating the motor 221, which has superior energy efficiency.

[0032] Furthermore, the plunger pump 10 is further equipped with a pressure measuring unit 212. The pressure measuring unit 212 measures the pressure of the compressed air discharged from the pressure adjustment unit 211. When the drive mode is set to the second mode, the control unit 40 switches the drive mode from the second mode to the first mode if the pressure of the compressed air measured by the pressure measuring unit 212 changes.

[0033] According to this, when the pressure of the compressed air measured by the pressure measuring unit 212 changes, it can be determined that the pump unit 30 has restarted from the standby state, and the drive mode can be switched from the second mode to the first mode. This allows the plunger pump 10 to operate smoothly.

[0034] Although one embodiment of the present invention has been described above, this embodiment is presented as an example and is not limited to the embodiments described above and shown in the drawings. It can be modified as appropriate without departing from the spirit of the invention. [Explanation of symbols]

[0035] 10…Plunger pump (pump device), 20…Drive unit, 211…Pressure adjustment unit, 212…Pressure measurement unit, 221…Motor, 30…Pump unit, 40…Control unit

Claims

[Claim 1] A pump unit capable of dispensing the coating liquid, A drive device having a motor driven by electric power, a pressure adjustment unit that adjusts and discharges the pressure of compressed air supplied from an external compressed air supply source, and a drive device that supplies driving force to the pump section, A control unit that controls the discharge of the coating liquid from the pump unit by switching between a first method for driving the motor and a second method for driving the pressure adjustment unit, The system includes a pressure measuring unit for measuring the pressure of the compressed air discharged from the pressure adjustment unit, The control unit, The drive method is set to the first method when the coating liquid is discharged from the pump unit, and the drive method is set to the second method when the coating liquid is not discharged from the pump unit. If the drive system is set to the first system and no coating liquid is discharged from the pump unit for a predetermined period of time, the drive system is switched from the first system to the second system. When the drive mode is set to the second mode, if the pressure of the compressed air measured by the pressure measuring unit changes, the drive mode is switched from the second mode to the first mode. Pumping device.

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