JP7525899B2 - DC pump control device, control program, and control method - Google Patents

Description

The present invention relates to a control device, control program, and control method for a DC pump mounted in, for example, a pure water production device, a pure water sampling device, etc.

In research institutions and other places, pure water production equipment equipped with diaphragm-type DC pumps (also called direct current liquid pumps) is used.

Various technologies have been proposed relating to such pure water production apparatus and control methods (for example, Patent Document 1).

JP 2010-75912 A

However, pure water production equipment such as that described above is required to have the ability to reduce the water sampling flow rate to a drip level and precisely sample the required amount of water in order to conduct precise experiments, etc.

Here, when a DC pump (diaphragm type) installed in a pure water production system or the like is driven with general PWM (pulse width modulation) control, if the output falls below a certain level, the pulsation of the DC pump causes the liquid to stop being pumped. It was found that if the output is further reduced, the DC pump itself will stop working even though a voltage is being applied to it.

Although the pulsation itself can be suppressed by installing a pressure reducing valve on the secondary side of the DC pump, this can cause the flow rate to drop to that during normal use (such as when the pump is at maximum output).

The present invention has been made in consideration of the above problems, and aims to provide a control device, control program, and control method for a DC pump that can maintain the flow rate during normal use, suppress pulsation at low output, and deliver the required amount of liquid with precision.

In order to achieve the above object, a DC pump control device according to an embodiment of the present invention is a DC pump control device that controls the drive of an actuator provided in a DC pump that delivers liquid, and comprises: actuator control means that PWM controls the drive of the actuator using a first control signal consisting of a predetermined PWM signal in order to maintain a flow rate during normal use of the DC pump; unstable state detection means that detects an unstable state of operation of the DC pump; control signal generation means that, when the unstable state is detected by the unstable state detection means, performs PWM control to periodically change the first control signal within a predetermined range to generate a second control signal; and precise liquid delivery means that, when the unstable state is detected, inputs the second control signal generated by the control signal generation means to the actuator control means to periodically turn the DC pump on and off to deliver precise liquid.

This allows the flow rate to be maintained during normal use, while suppressing pulsation at low output, allowing for precise delivery of the required amount of liquid. This makes it possible to collect minute amounts of water in a dripping state during experiments, etc., improving convenience.

The actuator can also include a DC motor that drives a diaphragm mechanism that delivers the liquid.

This allows DC pumps of typical configurations to suppress pulsation at low output and deliver the required amount of liquid with precision.

The control signal generating means can generate the second control signal so that one pulse of the second control signal is the minimum output within a range in which the DC pump operates stably.

This allows for more precise delivery of the required amount of fluid.

The second control signal may also include multiple types of PWM control waveforms with different duty ratios.

This allows a relatively simple method to maintain the flow rate during normal use, suppress pulsation at low output, and deliver the required amount of fluid precisely.

The unstable state detected by the unstable state detection means can include a state in which the pulsation state of the liquid delivered by the DC pump exceeds a predetermined reference value, or a state in which the liquid delivery by the DC pump has stopped.

This makes it possible to detect unstable states using relatively simple methods.

A control program according to another embodiment of the present invention is a DC pump control program for controlling the driving of an actuator provided in a DC pump that delivers liquid, the control program comprising: an actuator control step for PWM-controlling the driving of the actuator using a first control signal consisting of a predetermined PWM signal in order to maintain a flow rate during normal use of the DC pump; an unstable state detection step for detecting an unstable state of operation of the DC pump; a control signal generation step for, when the unstable state is detected in the unstable state detection step, performing PWM control to periodically change the first control signal within a predetermined range to generate a second control signal; and a precise liquid delivery step for, when the unstable state is detected, inputting the second control signal generated in the control signal generation step to periodically turn the DC pump on and off to deliver liquid precisely, and the program is executed by a computer provided in a control unit of the DC pump.

This allows the flow rate to be maintained during normal use, while suppressing pulsation at low output, allowing for precise delivery of the required amount of liquid. This makes it possible to collect minute amounts of water in a dripping state during experiments, etc., improving convenience.

Furthermore, a control method according to another embodiment of the present invention is a DC pump control method for controlling the drive of an actuator provided in a DC pump that delivers liquid, and is summarized as having an actuator control process for PWM-controlling the drive of the actuator using a first control signal consisting of a predetermined PWM signal in order to maintain a flow rate during normal use of the DC pump; an unstable state detection process for detecting an unstable state of operation of the DC pump; a control signal generation process for, when the unstable state is detected, performing PWM control to periodically change the first control signal within a predetermined range to generate a second control signal; and a precise liquid delivery process for, when the unstable state is detected, inputting the second control signal generated in the control signal generation process and periodically turning the DC pump on and off to deliver liquid precisely.

This allows the flow rate to be maintained during normal use, while suppressing pulsation at low output, allowing for precise delivery of the required amount of liquid. This makes it possible to collect minute amounts of water in a dripping state during experiments, etc., improving convenience.

The present invention provides a control device, control program, and control method for a DC pump that can maintain the flow rate during normal use, suppress pulsation at low output, and deliver the required amount of liquid with precision.

1 is a schematic diagram showing the overall configuration of a pure water sampling device equipped with a DC pump control device according to an embodiment; FIG. 1 is a schematic diagram showing a configuration example of a diaphragm type DC pump. 2 is a functional block diagram showing a functional configuration of a control device for a DC pump according to an embodiment; FIG. FIG. 1A is a waveform diagram showing a PWM waveform corresponding to a first control signal during normal water sampling operation of the DC pump, and FIG. 1B is a waveform diagram showing a PWM waveform corresponding to a second control signal during precision water sampling operation of the DC pump. 4 is a flowchart showing a procedure of a DC pump control process executed by the DC pump control device according to the embodiment. 11 is a flowchart showing a process procedure of a first precision liquid transfer process that can be executed by the DC pump control device according to the embodiment. 10 is a flowchart showing the procedure of a second precision liquid transfer process that can be performed by the DC pump control device according to the embodiment. 1 is a graph showing the flow rate control output of a DC pump. 1A to 1D are explanatory diagrams showing examples of switching of a control signal in a stable operating region and an unstable operating region of a DC pump.

With reference to Figures 1 to 9, a DC pump control device and the like according to an embodiment of the present invention will be described.

(Example of the configuration of a pure water sampling device)
First, prior to a detailed description of the DC pump control device 200 according to the present embodiment, a configuration example of a pure water sampling device M1 to which the control device 200 can be applied will be described with reference to Fig. 1. The pure water sampling device M1 can be connected to a pure water production device (not shown) or the like.

Here, FIG. 1 is a schematic diagram showing the overall configuration of a pure water sampling device M1 equipped with a DC pump control device 200 according to this embodiment.

The pure water sampling device M1 shown in FIG. 1 is a device for supplying pure water W produced by a pure water production device (not shown) to a container such as a beaker or measuring cylinder to be used in an experiment, etc., to sample the required amount of pure water W.

As shown in FIG. 1, the pure water sampling device M1 includes a pure water tank 101 for storing pure water W.

A DC pump 500, such as a diaphragm type, is connected to the pure water tank 101. The DC pump 500 is equipped with an actuator 300 having a coil 301 for an electromagnet, which will be described later.

A flow sensor SN1 that detects the flow rate of the pure water W is disposed on the discharge side of the DC pump 500. In addition, a solenoid valve 102 that adjusts the flow rate of the pure water W is provided downstream of the flow sensor SN1. A water inlet 103 that discharges the pure water W is provided downstream of the solenoid valve 102.

The DC pump 500 is also connected to a control device 200 that controls the drive of the actuator 300 to control the pump output in the range of 1 to 100%.

The control device 200 is configured, for example, as a microcomputer, and is configured to receive feedback of the detection signal from the flow sensor SN1.

The control device 200 has a function for monitoring the output to the DC pump 500, and is configured to be able to adjust the output according to the settings. This monitoring function enables the detection of abnormalities such as overload and overcurrent of the DC pump 500.

Furthermore, the flow sensor SN1 may be a sensor with a changeable measurement range. Furthermore, multiple flow sensors with different measurement ranges may be used.

A DC power supply (direct current power supply) 250 with a predetermined output is connected to the control device 200. In addition, a display operation panel 260 consisting of a touch panel or the like is connected to the control device 200, and is configured so that the water sampling flow rate can be set in the range of 1 to 100%.

When the pure water sampling device M1 actually delivers liquid, the control device 200 outputs a drive signal (first control signal P1 or second control signal P2) to the DC pump 500, and also outputs a predetermined drive signal to the solenoid valve 102 to open the piping path.

At this time, in order to avoid applying pressure inside the piping, a time difference may be provided between the output of the drive signals from the DC pump 500 and the solenoid valve 102.

The pure water sampling device M1 configured in this way is capable of controlling the flow rate (flow velocity) of the pure water W discharged from the water sampling port 103 within the range of 1 to 100% under the control of the control device 200.

The scope of application of the control device 200 is not limited to the pure water sampling device M1, but can be applied to any device that requires precise delivery of various liquids.

The specific control contents by the control device 200 will become clear from the description below.

(Example of the configuration of a diaphragm type DC pump)
An example of the configuration of a diaphragm-type DC pump 500 that can be controlled by the DC pump control device 200 according to this embodiment will be described with reference to FIG.

Here, FIG. 2 is a schematic diagram showing an example configuration of the DC pump 500.

The DC pump 500 is composed of a pump body 400 and an actuator 300.

The actuator 300 is connected to the control device 200 and includes a coil 301 for an electromagnet to which a pulse current constituting a first control signal P1 or a second control signal P2 described below is supplied, a core portion 302 that can move the coil 301 back and forth in the left and right directions in the figure, a plunger 305 that extends from the core portion 302 to the right in the figure, and a spring 304 that biases the core portion 302 to the right in the figure.

With this configuration, the plunger 305 of the actuator 300 reciprocates in a predetermined cycle in the left-right direction in the figure due to the pulse current that constitutes the first control signal P1 or the second control signal P2 supplied to the coil 301.

The pump body 400 is equipped with a diaphragm 450 that is connected to the plunger 305 of the actuator 300 and reciprocates left and right in the figure. In addition, due to the change in volume within the pump chamber caused by the reciprocating motion of the diaphragm 450, liquid such as pure water W is sucked up to the upper part of the figure through the suction port 401 and the valve 402. The sucked up liquid such as pure water W is configured to be discharged through the valve 405 and the discharge port 404 located at the top of the figure.

Due to the nature of its mechanism, the diaphragm-type DC pump 500 configured in this way generates pulsations when pumping liquid. Although the pulsations are smoothed to some extent at high output because the pump rotation speed is fast, there is the inconvenience that at low output the pump rotation speed slows down and the pulsations become more pronounced.

Therefore, if the DC pump 500 continues to be driven by the first control signal P1 using normal PWM control, when the output falls below a certain level, the pulsation of the DC pump 500 will cause the liquid to stop being pumped, and if the output is further reduced, the DC pump 500 will no longer operate despite the voltage being applied, making it impossible to pump liquid.

To eliminate such inconveniences, in the present invention, by switching the first control signal P1 or the second control signal P2 at a predetermined timing as described below, the flow rate during normal use is maintained, pulsation during low output is suppressed, and the DC pump 500 can be controlled to deliver the required amount of liquid precisely.

The DC pump that can be controlled by the control device 200 according to this embodiment is not limited to the diaphragm type DC pump 500 configured as shown in FIG. 2, but can be widely applied to bellows type DC pumps, tube type DC pumps, gear pumps using DC motors, rotary pumps, screw pumps, etc.

(Example of functional configuration of DC pump control device)
An example of the functional configuration of the DC pump control device according to the present embodiment will be described with reference to FIG.

Here, FIG. 3 is a functional block diagram showing the functional configuration of the control device 200 for the DC pump 500 etc. according to the embodiment.

The control device 200 for the DC pump 500, etc., is composed of a microcomputer or the like that controls the operation of the actuator 300 provided in the DC pump 500, etc., which delivers pure water W, etc.

As shown in FIG. 3, the control device 200 includes an actuator control means 201 that PWM-controls the drive of the actuator 300 using a first control signal P1 consisting of a predetermined PWM signal when the DC pump 500 is in a normal operating state.

The control device 200 also includes an unstable state detection means 202 that detects an unstable state of the operation of the DC pump 500.

The control device 200 also includes a control signal generating means 203 that performs PWM control with a predetermined variable period on the first control signal P1 to generate a second control signal P2 when an unstable state is detected by the unstable state detecting means 202.

Furthermore, when an unstable state is detected, the device is provided with a precision liquid delivery means 204 that inputs a second control signal P2 generated by the control signal generation means 203 to the actuator control means 201 to periodically turn the DC pump 500 on and off to perform precise liquid delivery.

The control device 200 configured in this way makes it possible to maintain the flow rate of the DC pump 500 and other pumps during normal use, while suppressing pulsation at low output, and to precisely deliver the required amount of liquid. This makes it possible to collect minute amounts of water in a dripping state (e.g., 10 ml/min or less) during experiments, improving convenience.

The actuator 300 can also include an electromagnetic device or DC motor that drives a diaphragm mechanism that delivers pure water W or the like, as shown in FIG. 2. This makes it possible to suppress pulsation at low output in a DC pump 500 or the like of a general configuration, and deliver the required amount of liquid with precision.

The control signal generating means 203 may generate the second control signal P2 so that one pulse of the second control signal P2 is the minimum output within the range in which the DC pump 500 or the like operates stably. This makes it possible to more precisely deliver the required amount of liquid.

The second control signal P2 can also include multiple types of PWM control waveforms with different duty ratios. This allows a relatively simple method to maintain the flow rate during normal use, suppress pulsation during low output, and achieve precise delivery of the required amount of fluid.

The unstable state detected by the unstable state detection means 202 can include a state in which the pulsation state of the liquid delivered by the DC pump 500 or the like exceeds a predetermined reference value, or a state in which the liquid delivery by the DC pump 500 or the like has stopped.

That is, while changing the pump output of the DC pump 500, etc., the feedback signal detects when the pump operation becomes unstable (significant pulsation, not being driven, etc.), and in the output range where the pump operation becomes unstable, the first control that is normally PWM controlled is changed to PWM control with a variable period to periodically turn the DC pump 500, etc. on and off. At this time, one pulse of the second control signal P2 that is input is set to the minimum output within the range where the DC pump 500, etc. operates stably.

This makes it possible to detect unstable states using relatively simple methods.

More specific control methods will be described later.

(Examples of First Control Signal and Second Control Signal)
With reference to FIG. 4, examples of the first control signal P1 and the second control signal P2 used to control the DC pump 500 and the like will be described.

Figure 4(a) is a waveform diagram showing a PWM waveform corresponding to the first control signal P1 during normal water sampling operation of the DC pump 500, etc., and Figure 4(b) is a waveform diagram showing a PWM waveform corresponding to the second control signal P2 during precision water sampling operation of the DC pump 500, etc.

First, PWM control is a control that replaces the magnitude of the input signal with a duty ratio (ON:OFF ratio) for a certain period T. The magnitude X of the target input signal and the duty ratio are equal, for example, as shown below.

Input signal X = 100% Duty ratio (100:0)
Input signal X = 50% duty ratio (50:50)
Input signal X = 0% duty ratio (0:100)
Here, as shown in FIG. 4(a), it is assumed that the first control signal (pump PWM output signal) P1 of the DC pump 500 or the like during normal water sampling operation has a period between pulses P1a and P1b of 20 kHz, for example.

In this case, the more the output is reduced in normal PWM control using the first control signal P1, the more pronounced the pulsation of the DC pump 500, etc. If the output is reduced further, the delivery of the pure water W, etc. will be interrupted, and ultimately the signal for the time required to drive the DC pump 500, etc. will no longer be applied, resulting in the DC pump 500, etc. not operating. Therefore, with PWM control using only the first control signal P1, precise water sampling at a drip level cannot be performed.

Therefore, in the present invention, during low output when the DC pump 500 etc. pulsates more than a predetermined amount or does not operate, control is performed using a second control signal (pump PWM output signal) P2 that is different from the first control signal (pump PWM output signal) P1.

That is, in the example shown in FIG. 4(b), when the period between pulses P2a and P2b is 20 kHz, the PWM setting value of pulses P2a, P2b, P2c, etc. is set to 15% of that in the case of the first control signal P1.

In the example shown in FIG. 4(b), the pump output time of the second control signal (pump PWM output signal) P2 is calculated by pump output value (%)/15 (%) x pump output N% cycle (ms). The setting range of the pump output N% cycle can be 5 to 2000 ms.

Here, we explain an example of generalizing the second control signal (pump PWM output signal) P2.

For example, in the second control signal P2, the waveform with a period T is designated as A. The duty ratio of the waveform A is designated as an output value Y within the range in which the DC pump 500 etc. operates stably.

Next, PWM control is further performed on waveform A with a period T' (T<<T') different from the period of waveform A, and the result is waveform B.

The magnitude X of the input signal in this control is the duty ratio of waveform B, not the duty ratio of waveform A.

Then, by making the period T and the period T' variable parameters and adjusting the period T and the period T' according to the magnitude of the input signal, stable pump operation is possible even at low output where normal PWM control using the first control signal P1 is not possible.

In addition, by driving the DC pump 500 etc. intermittently at a large cycle, it is possible to achieve drip-level liquid delivery, making it possible to deliver precise amounts of liquid.

As such, with normal PWM control using the first control signal P1, the pump output was limited to a lower limit of about 13%, and the flow rate was limited to a performance limit of about 150 mL/min. In contrast, with control using the second control signal P2 appropriately, it became possible to deliver liquid at a drip level (water collection flow rate of 10 mL/min or less).

(Regarding DC pump control process)
The procedure of the DC pump control process executed by the DC pump control device 200 will be described with reference to the flowchart of FIG.

This process can be implemented by cooperation between the OS (operating system) of the control device 200 and a specific application program. However, some or all of the various functions may be implemented by hardware.

When this process starts, first in step S10, the actuator 300 is driven using the first control signal (pump PWM output signal) P1 to perform normal operation of the DC pump 500, etc.

Next, in step S11, it is determined whether an unstable state of the DC pump 500 or the like (such as a state in which pulsation of a predetermined magnitude or more has occurred, or the actuator 300 has stopped) has been detected.

The determination of whether or not a detection has occurred can be made, for example, using the pump output α% described below as a threshold value.

If the result of the judgment is "No", return to step S10 and continue normal operation, and if the result is "Yes", proceed to step S12.

In step S12, the second control signal (pump PWM output signal) P2 is generated using the method described above, and the process proceeds to step S13.

In step S13, the second control signal (pump PWM output signal) P2 is used to perform precise liquid delivery, such as adjusting the drip level, and then the process is completed.

The DC pump 500 and the like are capable of continuous output (PWM output of 10 kHz to 30 kHz) within the stable operating range of the pump (100% to α%).

By using this type of processing, it is possible to automatically control the unstable operating range (1% to α%) where pulsation phenomena occur in DC pumps 500 and the like, and to control the pump output period according to the output setting value.

The threshold for determining whether the DC pump 500 or the like is in an unstable state in step S11 needs to be adjusted depending on the characteristics of the pump being used.

There are two main methods for determining this:

a) A method of automatic determination and tuning using a high-precision flow sensor that can measure minute flow rates. b) A method of manually setting the output table of the minute flow rate control region when an inexpensive, low-precision flow sensor is used. The liquid delivery processes based on each determination method will be described later as the first precision liquid delivery process and the second precision liquid delivery process.

(Regarding the first precise liquid transfer process)
The processing steps of the first precise liquid transfer processing based on the above-mentioned determination method a) will be described with reference to the flowchart of FIG.

The first precision liquid delivery process can be executed as an interrupt process every 1 ms to the CPU or the like provided in the control device (microcomputer, etc.) 200.

In step S20, it is determined whether the flow measurement result is less than or equal to the unstable operating flow rate, and if the result is "Yes," the process proceeds to step S21.

In step S21, the pump output time is calculated and the process proceeds to step S22. In step S22, the 1 ms counter is incremented by "1" and the process proceeds to step S23.

In step S23, it is determined whether the 1 ms counter is greater than or equal to the pump output period.

If the result of the judgment is "No", proceed to step S25; if the result is "Yes", proceed to step S24.

In step S24, the 1 ms counter is reset to "0" and the process proceeds to step S25.

In step S25, it is determined whether the 1 ms counter is equal to or greater than the pump output time. If the determination result is "Yes", the PWM setting value is set to "0" in step S26 and the process proceeds to step S27.

If the result of the determination is "No", the process proceeds to step S28, where the PWM setting value is set to "α%" and the process proceeds to step S27.

In step S27, the PWM setting value and PWM output are set and the process ends.

On the other hand, if the answer is "No" in step S20, the process proceeds to step S29. In step S29, the PWM setting value is set to the pump output value, and the process proceeds to step S30.

In step S30, it is determined whether the pump output α% is greater than the PWM set value.

If the determination is "No", proceed to step S27; if the determination is "Yes", proceed to step S31.

In step S31, α is set to the PWM setting value and the process proceeds to step S27.

This process enables more precise liquid delivery in a configuration that uses a high-precision flow sensor that can measure minute flow rates.

For example, the following cases also fall under the above determination method a):

a) When the fluctuation range of the flow rate per unit time exceeds a certain range. For example, this would be the case if the flow rate fluctuates by ±10% per second.

b) When a flow rate of 0 ml/min is detected for a certain period of time or longer at an output other than 0%. For example, this applies when a flow rate of 0 ml/min is detected for 0.5 seconds at an output of 15%.

In addition, in the process shown in FIG. 6, the unstable output range can be automatically determined by the above-mentioned determination method a), so the value of "α" can be set either automatically or manually.

(Second Precision Liquid Delivery Process)
The processing steps of the second precise liquid transfer processing based on the above-mentioned determination method b) will be described with reference to the flowchart of FIG.

The second precision liquid delivery process can be executed as an interrupt process every 1 ms to the CPU or the like of the control device (microcomputer or the like) 200.

First, in step S40, it is determined whether 1% < pump output value < α%. If the determination result is "Yes", the process proceeds to step S41.

In step S41, the pump output time is calculated and the process proceeds to step S42.

In step S42, the 1 ms counter is incremented by "1" and the process proceeds to step S43.

In step S43, it is determined whether the 1 ms counter is greater than or equal to the pump output period. If the determination result is "No", the process proceeds to step S45, and if the determination result is "Yes", the process proceeds to step S44.

In step S44, the 1 ms counter is reset to "0" and the process proceeds to step S45.

In step S45, it is determined whether the 1 ms counter is equal to or greater than the pump output time. If the determination result is "Yes", the PWM setting value is set to "0" in step S46 and the process proceeds to step S47.

If the result of the determination is "No", the process proceeds to step S48, where the PWM setting value is set to "α%" and the process proceeds to step S47.

In step S47, the PWM setting value and PWM output are set and the process ends.

On the other hand, if step S40 returns "No," the process proceeds to step S49. In step S49, the PWM setting value is set to the pump output value, and the process proceeds to step S47.

This process makes it possible to perform more precise fluid delivery in configurations that use inexpensive, low-precision flow sensors.

Note that in the process shown in Figure 7, the output table needs to be manually adjusted using the above determination method b), so the value of "α" can only be set manually.

Note that FIG. 8 is a graph showing the flow rate control output of the DC pump 500 etc. when the precision liquid delivery process described above is performed. This graph shows the relationship between the set input (0 to 100%) and the pump output voltage (V).

As can be seen from the graph in Figure 8, the flow rate control results show a nearly flat linearity at the set input (0 to 100%), making it possible to obtain smooth water sampling over the entire range of settings.

(Switching pump signals from stable to unstable operating ranges)
9A to 9D are explanatory diagrams showing examples of switching of a control signal in a stable operating region and an unstable operating region of a DC pump.

Figures 9(a) to (d) show the step-by-step waveforms in the transition from the stable operating region to the unstable operating region.

Figure 9 (a) illustrates pump control signal P10 (P10a, P10b, etc.) when the pump output is 16% (=stable region) when the minimum output value α in the stable operating region is 15%, and corresponds to the waveform of the first control signal P1 when the output is 16%.

Figure 9 (b) illustrates pump control signal P11 (P11a, P11b...) when the pump output is 15% (=stable region) when the minimum output value α in the stable operating region is 15%, and corresponds to the waveform of the first control signal P1 when the output is 15%.

Figure 9 (c) illustrates pump control signal P12 (P12a, P12b, etc.) when the pump output is 14% (=stable region) when the minimum output value α in the stable operating region is 15%, and corresponds to the waveform of the second control signal P2 when the output is 14%.

Figure 9 (d) illustrates pump control signal P13 (P13a, P13b, etc.) when the pump output is 13% (=stable region) when the minimum output value α in the stable operating region is 15%, and corresponds to the waveform of the second control signal P2 when the output is 13%.

The DC pump control device of the present invention has been described above based on the illustrated embodiment, but the present invention is not limited to this, and the configuration of each part can be replaced with any configuration having a similar function.

M1 Pure water sampling device 200 Control device 201 Actuator control means 202 Unstable state detection means 203 Control signal generation means 204 Precision liquid delivery means 300 Actuator 500 DC pump P1 First control signal P2 Second control signal SN1 Flow rate sensor

Claims (7)

A DC pump control device that controls driving of an actuator provided in a DC pump that delivers liquid,
an actuator control means for PWM-controlling the drive of the actuator using a first control signal consisting of a predetermined PWM signal in order to maintain a flow rate of the DC pump during normal use ;
an unstable state detection means for detecting an unstable state of the operation of the DC pump;
a control signal generating means for performing PWM control for periodically varying the first control signal within a predetermined range when the unstable state is detected by the unstable state detecting means, to generate a second control signal;
a precision liquid delivery means for, when the unstable state is detected, inputting the second control signal generated by the control signal generation means to the actuator control means to periodically turn on and off the DC pump to perform precise liquid delivery;
A DC pump control device comprising: The DC pump control device according to claim 1, characterized in that the actuator includes a DC motor that drives a diaphragm mechanism that delivers liquid. The DC pump control device according to claim 1 or 2, characterized in that the control signal generating means generates the second control signal so that one pulse of the second control signal is the minimum output within a range in which the DC pump operates stably. The DC pump control device according to any one of claims 1 to 3, characterized in that the second control signal includes a plurality of types of PWM control waveforms with different duty ratios. The DC pump control device according to any one of claims 1 to 4, characterized in that the unstable state detected by the unstable state detection means includes a state in which the pulsation state of the liquid delivered by the DC pump exceeds a predetermined reference value, or a state in which the liquid delivery by the DC pump has stopped. A control program for a DC pump that controls driving of an actuator provided in a DC pump that delivers liquid,
an actuator control step of PWM-controlling the drive of the actuator using a first control signal consisting of a predetermined PWM signal in order to maintain a flow rate of the DC pump during normal use ;
an unstable state detection step of detecting an unstable state of the operation of the DC pump;
a control signal generating step of performing PWM control for periodically varying the first control signal within a predetermined range to generate a second control signal when the unstable state is detected in the unstable state detecting step;
a precise liquid delivery step of, in a state where the unstable state is detected, inputting the second control signal generated in the control signal generation step to periodically turn on and off the DC pump to perform precise liquid delivery;
A DC pump control program comprising: A method for controlling a DC pump that controls driving of an actuator provided in a DC pump that delivers liquid, comprising:
an actuator control process for PWM-controlling the drive of the actuator using a first control signal consisting of a predetermined PWM signal in order to maintain a flow rate of the DC pump during normal use ;
an unstable state detection step of detecting an unstable state of the DC pump;
a control signal generating step of performing PWM control to periodically vary the first control signal within a predetermined range when the unstable state is detected, thereby generating a second control signal;
a precise liquid delivery process in which, when the unstable state is detected, the second control signal generated in the control signal generation process is input to the DC pump to periodically turn on and off the DC pump to perform precise liquid delivery;
A method for controlling a DC pump comprising:

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