WO2020040131A1 - Dispositif de pompe - Google Patents

Dispositif de pompe Download PDF

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Publication number
WO2020040131A1
WO2020040131A1 PCT/JP2019/032422 JP2019032422W WO2020040131A1 WO 2020040131 A1 WO2020040131 A1 WO 2020040131A1 JP 2019032422 W JP2019032422 W JP 2019032422W WO 2020040131 A1 WO2020040131 A1 WO 2020040131A1
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WIPO (PCT)
Prior art keywords
piezoelectric pump
pump
voltage
piezoelectric
frequency
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PCT/JP2019/032422
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English (en)
Japanese (ja)
Inventor
健二朗 岡口
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株式会社村田製作所
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Publication date
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Publication of WO2020040131A1 publication Critical patent/WO2020040131A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B43/00—Machines, pumps, or pumping installations having flexible working members
    • F04B43/02—Machines, pumps, or pumping installations having flexible working members having plate-like flexible members, e.g. diaphragms
    • F04B43/04—Pumps having electric drive
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B45/00—Pumps or pumping installations having flexible working members and specially adapted for elastic fluids
    • F04B45/04—Pumps or pumping installations having flexible working members and specially adapted for elastic fluids having plate-like flexible members, e.g. diaphragms
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B45/00—Pumps or pumping installations having flexible working members and specially adapted for elastic fluids
    • F04B45/04—Pumps or pumping installations having flexible working members and specially adapted for elastic fluids having plate-like flexible members, e.g. diaphragms
    • F04B45/047—Pumps having electric drive
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details

Definitions

  • the present invention relates to a pump device, and more particularly to a pump device including a piezoelectric pump.
  • a pump device equipped with a piezoelectric pump has been used as a gas suction device or a pressure device.
  • the piezoelectric pump is driven by the vibration of the piezoelectric element.
  • the size of the pump device can be reduced.
  • the piezoelectric element vibrates periodically by applying an AC voltage to the piezoelectric element. Thereby, the pressure in the container can be changed.
  • the frequency of the applied AC voltage is called a driving frequency of the piezoelectric pump.
  • the driving frequency of the piezoelectric pump is predetermined at room temperature.
  • the piezoelectric pump when the temperature of the piezoelectric pump is lower than the normal temperature, the output decreases, and when the temperature of the piezoelectric pump becomes higher than the normal temperature, the electric efficiency decreases.
  • the piezoelectric pump has a temperature characteristic. Therefore, as a technique for correcting the temperature characteristics of the piezoelectric pump, use of a temperature compensation technique used in a crystal oscillator can be considered.
  • a thermistor is provided outside the crystal oscillator to detect an environmental temperature, and compensate for the oscillation frequency of the crystal according to the detected temperature.
  • a pump device including a piezoelectric pump, which can drive the piezoelectric pump in accordance with the temperature of the piezoelectric pump.
  • a piezoelectric pump A voltage detection unit that detects an applied voltage applied to the piezoelectric pump, A control unit that drives the piezoelectric pump based on the applied voltage at a first frequency outside a driving frequency band capable of driving the piezoelectric pump, and determines a second frequency within the driving frequency band, It is a pump apparatus provided with.
  • the pump device of the present invention in a pump device including a piezoelectric pump, it is possible to provide a pump device that can be driven according to the temperature of the piezoelectric pump.
  • FIG. 6 is a graph showing the relationship between output voltage Vo and temperature at different frequencies.
  • Flow chart showing the flow of drive control of the piezoelectric pump according to the first embodiment.
  • FIG. 4 is a graph showing an example of a relationship between time and temperature of a piezoelectric pump in drive control.
  • FIG. 4 is a graph showing an example of a relationship between time and frequency in drive control.
  • Graph showing the electrical efficiency of the pump device 5 is a circuit diagram showing a modification of the drive circuit and the voltage detection circuit according to the first embodiment. Explanatory diagram showing the direction in which a fluid flows in Embodiment 2.
  • FIG. 6 is a graph showing a relationship between time and pressure of the pump device according to the second embodiment.
  • Block diagram of a pump device according to Embodiment 3. Flow chart showing the flow of drive control of the piezoelectric pump according to the third embodiment.
  • Circuit diagram of drive circuit and voltage detection circuit in Embodiment 3 Circuit diagram of an amplifier circuit according to Embodiment 3. Explanatory drawing showing the direction in which a fluid flows in Embodiment 4.
  • Circuit diagram of drive circuit and voltage detection circuit in Embodiment 4
  • a pump device includes a piezoelectric pump, a voltage detection unit that detects an applied voltage applied to the piezoelectric pump, and a first frequency outside a driving frequency band capable of driving the piezoelectric pump.
  • a control unit that drives the piezoelectric pump based on the applied voltage and determines a second frequency in the drive frequency band.
  • the voltage applied to the piezoelectric pump at the first frequency outside the driving frequency band of the piezoelectric pump is detected. Since the value of the applied voltage corresponds to the temperature of the piezoelectric pump, the second frequency for driving the piezoelectric pump is determined based on the detected applied voltage, so that an appropriate value corresponding to the temperature change of the piezoelectric pump can be obtained.
  • the piezoelectric pump can be driven at an appropriate frequency. Thus, the output of the piezoelectric pump at low temperatures and the electrical efficiency at high temperatures can be improved.
  • an impedance element electrically connected to the piezoelectric pump may be provided, and the voltage detection unit may measure the applied voltage from a voltage divided by the piezoelectric pump and the impedance element. According to such a configuration, the applied voltage of the piezoelectric pump can be easily detected.
  • a power supply unit that supplies power to the piezoelectric pump may be provided, and the control unit may be connected to the power supply unit and adjust power supplied to the piezoelectric pump according to an output voltage of the piezoelectric pump. . According to such a configuration, since the power supplied from the power supply unit can be adjusted according to the output voltage of the piezoelectric pump, overheating of the piezoelectric pump can be prevented.
  • control unit may be configured to perform the second step based on a modeled relationship between the capacity of the piezoelectric pump and the temperature of the piezoelectric pump, or a relationship between the output voltage of the piezoelectric pump and the temperature of the piezoelectric pump. May be determined.
  • the impedance element may be a resistor.
  • the impedance element may be an inductor.
  • the input voltage when detecting the divided output voltage may be lower than when the piezoelectric pump is driven in a driving frequency band. According to such a configuration, power consumption can be reduced.
  • FIG. 1 is a schematic sectional view of a piezoelectric pump.
  • FIG. 2 is an explanatory diagram showing the operation of the piezoelectric pump.
  • the piezoelectric pump 21 includes a cover plate 22, a channel plate 23, an opposing plate 24, an adhesive layer 25, a vibration plate 26, a piezoelectric element 27, an insulating plate 28, a power supply plate 29, a spacer plate 30, and a cover plate 31 in this order. Laminated.
  • the piezoelectric pump 21 is thin in the stacking direction and has a rectangular shape in a plan view (as viewed from the stacking direction).
  • a suction port 33 is formed on the cover plate 22 side of the piezoelectric pump 21.
  • a discharge port 34 is formed on the lid plate 31 side of the piezoelectric pump 21.
  • a circular channel hole 37 is formed in the cover plate 22.
  • the channel plate 23 has a circular opening 38 formed therein.
  • the opening 38 communicates with the channel hole 37.
  • the diameter of the opening 38 is larger than the diameter of the flow path hole 37.
  • the opposing plate 24 is made of metal.
  • An external connection terminal 35 protruding outward and a circular suction port 33 are formed in the facing plate 24.
  • the suction port 33 communicates with the opening 38.
  • the diameter of the suction port 33 is smaller than the diameter of the opening 38.
  • a bendable movable portion 39 is formed around the suction port 33 of the opposing plate 24.
  • the adhesive layer 25 is formed in a frame shape so as to overlap the frame portion 44 of the diaphragm 26.
  • the adhesive layer 25 is composed of a thermosetting resin such as an epoxy resin and contains a plurality of conductive particles having a substantially uniform particle size. Thereby, the opposing plate 24 and the vibration plate 26 can be electrically conducted through the conductive particles of the adhesive layer 25.
  • the diaphragm 26 is made of metal such as SUS301, for example.
  • the vibration plate 26 faces the opposing plate 24 at a predetermined interval.
  • the gap between the opposing plate 24 and the diaphragm 26 constitutes a pump chamber 40.
  • the diaphragm 26 has a central portion 41, a hitting portion 42, a connecting portion 43, and a frame portion 44.
  • the central portion 41 has a circular shape in plan view, and is disposed at the center of the diaphragm 26.
  • the frame portion 44 has a frame shape in a plan view, and is arranged around the diaphragm 26.
  • the connecting portion 43 has a beam shape and connects the central portion 41 and the frame portion 44.
  • the hitting portion 42 has a circular shape in plan view, and is disposed near a boundary between the central portion 41 and the connecting portion 43.
  • the striking section 42 is arranged such that the center thereof faces the suction port 33.
  • the diameter of the hitting portion 42 is larger than the diameter of the suction port 33.
  • the hitting portion 42 and the frame portion 44 are thicker than the central portion 41 and the connecting portion 43.
  • the diaphragm 26 has an opening (not shown) surrounded by the components of the diaphragm 26 described above.
  • the pump chamber 40 communicates with the pump chamber 46 through the opening.
  • the piezoelectric element 27 is configured by providing electrodes on both main surfaces of a thin plate made of a piezoelectric material.
  • the piezoelectric element 27 has such a piezoelectric property that its area increases or decreases in the in-plane direction when an electric field is applied in the thickness direction.
  • the piezoelectric element 27 has a disk shape and is attached to the upper surface of the central portion 41 of the diaphragm 26.
  • the electrode on the lower surface of the piezoelectric element 27 is electrically connected to the external connection terminal 35 via the vibration plate 26, the adhesive layer 25, and the opposing plate 24.
  • the insulating plate 28 is made of an insulating resin.
  • the insulating plate 28 has a rectangular opening in a plan view.
  • the power supply plate 29 is made of metal.
  • the power supply plate 29 is formed with a rectangular opening in plan view, an internal connection terminal 45 protruding from the opening of the power supply plate 29, and an external connection terminal 36 protruding outward.
  • the tip of the internal connection terminal 45 is soldered to an electrode on the upper surface of the piezoelectric element 27.
  • the spacer plate 30 is made of resin.
  • the spacer plate 30 is formed with a rectangular opening in plan view.
  • the openings of the insulating plate 28, the power supply plate 29, and the spacer plate 30 communicate with each other to form a pump chamber 46.
  • the cover plate 31 is formed with a circular discharge port 34 in plan view.
  • the discharge port 34 communicates with the pump chamber 46 and the outside.
  • FIG. 2 is a schematic diagram showing the operation of the piezoelectric pump 21.
  • the piezoelectric pump 21 when an AC drive voltage is applied to the external connection terminals 35 and 36, the piezoelectric element 27 tries to expand and contract isotropically in the in-plane direction, and the piezoelectric element 27 and the vibration plate 26 are stacked. Flexural vibration in the thickness direction occurs concentrically. This bending vibration is a higher-order resonance mode, in which the frame portion 44 becomes a fixed portion, the center of the central portion 41 becomes an antinode of the first vibration, and the center of the hitting portion 42 becomes an antinode of the second vibration.
  • the vibration of the striking section 42 is transmitted to the movable section 39 via the fluid facing the striking section 42.
  • Fluid flows from the vicinity of the suction port 33 in the pump chamber 40 to the outer peripheral side of the movable portion 39 by coupling the vibration of the impact portion 42 and the vibration of the movable portion 39.
  • a negative pressure is generated around the suction port 33 in the pump chamber 40, and the fluid is sucked from the suction port 33 into the pump chamber 46.
  • a positive pressure is generated inside the pump chamber 46, and the positive pressure is released at the discharge port 34 of the cover plate 31. Therefore, the fluid sucked into the pump chambers 40 and 46 via the suction port 33 flows out of the pump chambers 40 and 46 via the discharge port 34.
  • the piezoelectric element 27, the diaphragm 26, and the opposing plate 24 of the piezoelectric pump 21 are called an engine.
  • the state in which the piezoelectric pump 21 is driven is a state in which the engine of the piezoelectric pump 21 bends and vibrates.
  • the state in which the piezoelectric pump 21 is driven refers to a state in which a fluid is sucked into the piezoelectric pump 21 or a fluid is discharged from the piezoelectric pump 21.
  • the non-driven state in which the piezoelectric pump 21 is not driven is a state in which fluid is not sucked into the piezoelectric pump 21 or a state in which fluid is not discharged from the piezoelectric pump 21.
  • FIG. 3 is a graph showing the relationship between pressure and electrical efficiency at different temperatures.
  • FIG. 3 shows the driving when the piezoelectric pump 21 is at 40 ° C.
  • the graph Gb is at 23 ° C.
  • the graph Gc is at 10 ° C. when the back pressure of the piezoelectric pump 21 is 380 mmHg.
  • the relationship between frequency and air flow is shown.
  • the optimum driving frequency Fga of the graph Ga, the optimum driving frequency Fgb of the graph Gb, and the optimum driving frequency Fgc of the graph Gc are different from each other. Therefore, when the drive frequency is set to Fgb so as to drive optimally when the drive frequency is 23 ° C., at an environment temperature of 10 ° C., the flow rate of the piezoelectric pump 21 becomes zero at a back pressure of 380 mmHg. Do not work. As described above, the pump output decreases when the temperature decreases from room temperature.
  • FIG. 4 is a graph showing the relationship between pressure and electrical efficiency at different temperatures.
  • FIG. 4 shows the electrical efficiency at each temperature when driven at the frequency Fgb of FIG.
  • the graph Gd shows the relationship between the respective pressures and the electrical efficiency when the piezoelectric pump 21 is at 50 ° C., the graph Gh at 25 ° C., and the graph Ge at 0 ° C.
  • the peak value of the electric efficiency varies depending on the temperature, and the electric efficiency decreases particularly at a high temperature. If the electric efficiency is poor, for example, when a battery is used as a power supply, the life of the battery is shortened, and the frequency of battery replacement and charging is increased, thereby reducing usability.
  • FIG. 5 is a graph showing the relationship between the driving frequency and the impedance at normal temperature, for example, 20 ° C.
  • the frequency characteristic of the piezoelectric pump 21 has a resonance frequency fr and an anti-resonance frequency fa.
  • the resonance frequency fr is about 23.4 kHz
  • the anti-resonance frequency fa is about 24.5 kHz.
  • a driving frequency band Fw in which the piezoelectric pump can be driven is between the resonance frequency fr and the anti-resonance frequency fa.
  • the frequency band lower than the resonance frequency fr and the frequency band higher than the anti-resonance frequency fa are non-drive frequency bands Fz.
  • FIG. 6 is an equivalent circuit diagram modeling the piezoelectric pump 21.
  • the non-drive frequency band Fz has a frequency characteristic of the capacitor Ca.
  • the resonance frequency fr has a frequency characteristic of a series circuit Da including the inductor L, the capacitor Cb, and the resistor R.
  • the anti-resonance frequency fa has a frequency characteristic of a parallel circuit Db including the LCR series circuit Da and the capacitor C.
  • the impedance is determined only by the capacitance Ca of the piezoelectric pump 21, so that the impedance is relatively stable with respect to an input voltage or a back pressure and is sensitive to temperature.
  • the non-drive frequency band including the non-drive frequency is, for example, a frequency region excluding a region between a resonance frequency at which the impedance is minimum and an anti-resonance frequency at which the impedance is maximum (in other words, the impedance is C-characteristic).
  • FIG. 7 is a graph showing the relationship between the temperature of the piezoelectric pump and the rate of change of the capacity.
  • FIG. 7 shows the relationship between the capacitance and the temperature at the non-drive frequency.
  • the capacity Ca at normal temperature is determined by the dielectric constant, thickness, and area of the piezoelectric pump 21, but the error is small. Therefore, if the capacitance Ca at the non-drive frequency of the piezoelectric pump 21 is known, the temperature can be accurately detected.
  • the capacity C and the impedance Z of the piezoelectric pump 21 have a reciprocal relationship.
  • the relationship between the impedance Z, the frequency f, and the capacitance C is represented by the following equation.
  • the optimum drive frequency at each temperature is determined by the design of the piezoelectric pump 21, and if the current value is determined, the optimum frequency is determined from the relationship between the current value and the optimum drive frequency as shown in FIG.
  • the drive frequency is determined according to the temperature change of the piezoelectric pump 21. This corresponds to determining the drive frequency of the piezoelectric pump 21 according to the impedance change of the piezoelectric pump 21 at the non-drive frequency.
  • FIG. 9 is a graph showing the relationship between the output voltage of the piezoelectric pump and the drive frequency correction amount.
  • the output voltage is a parameter that changes according to the temperature of the piezoelectric pump. Therefore, by correcting the drive frequency according to the output voltage, it is possible to appropriately drive the piezoelectric pump 21 in response to a temperature change. Since the temperature of the piezoelectric pump 21 is higher as the output voltage is higher, the drive frequency is corrected to be lower.
  • FIG. 10 is a block diagram showing a pump device according to the first embodiment.
  • the pump device 11 includes a piezoelectric pump 21, a drive circuit 12 for driving the piezoelectric pump 21, a voltage detection circuit 13 for detecting an output voltage of the piezoelectric pump 21, a power supply circuit 14 for supplying power to the drive circuit 12, A control unit for determining a drive frequency of the pump;
  • the control unit 15 includes a processing unit 16 and a storage unit 17.
  • the control unit 15 may be, for example, an MCU (Micro Control Unit) in which the processing unit 16 and the storage unit 17 are integrated, or may be provided separately.
  • the processing unit 16 may be a CPU, a microchip, or an FPGA.
  • the storage unit 17 may be a memory, a hard disk, or an SSD. In the first embodiment, a case where an MCU is employed as the control unit 15 will be described as an example.
  • the relationship between the output voltage Vo and the drive frequency fo is stored in the storage unit 17 as a relational expression or a table.
  • the relationship between the output voltage Vo and the driving frequency fo is calculated in advance from the modeled relationship between the capacity C of the piezoelectric pump 21 and the temperature of the piezoelectric pump 21 or the relationship between the output voltage Vo and the temperature of the piezoelectric pump 21. By doing so, the processing time is shortened.
  • the pump device 11 according to the first embodiment is used, for example, in a suction device 51 as shown in FIG.
  • FIG. 11 is an explanatory diagram illustrating the flow of the fluid in the suction device according to the first embodiment.
  • the suction device 51 includes a container 53 in which a fluid is stored, a piezoelectric pump 21 that sucks the fluid from the container 53, a valve 55, and a tube 57 that connects the container 53, the valve 55, and the piezoelectric pump 21.
  • the fluid may be a liquid or a gas.
  • suction device examples include a milking machine, NPWT (Negative Pressure Wound Therapy), drainage, and a runny suction device.
  • NPWT Negative Pressure Wound Therapy
  • FIG. 11 one piezoelectric pump 21 is connected to the container 53, but two or more piezoelectric pumps 21 may be connected to the container 53 in series.
  • FIG. 12 is a circuit diagram of the drive circuit 12 and the voltage detection circuit 13.
  • the drive circuit 12 is, for example, an H-bridge circuit.
  • the drive circuit 12 has four FETs, a first FET 61, a second FET 62, a third FET 63, and a fourth FET 64. Each of the FETs is switched by a drive signal from the control unit 15 to the first to fourth FETs 61 to 64, and an AC voltage having a predetermined frequency is applied to the piezoelectric pump 21.
  • the input voltage Vc is applied from the power supply circuit 14 to the drains of the first FET 61 and the third FET 63.
  • the source of the first FET 61 is connected to the drain of the second FET 62 and the external connection terminal 35 of the piezoelectric pump 21.
  • the source of the third FET 63 is connected to the drain of the fourth FET 64 and the external connection terminal 36 of the piezoelectric pump 21.
  • the source of the second FET 62 and the source of the fourth FET 64 are connected to the voltage detection circuit 13.
  • the voltage detection circuit 13 includes an impedance element that is electrically connected to the piezoelectric pump 21. As the impedance element, for example, a resistor Rs is used.
  • the DC input voltage Vc supplied from the power supply circuit 14 as a power supply unit is divided by the first FET 61, the piezoelectric pump 21, the fourth FET 64, and the resistor Rs, or divided by the third FET 63, the piezoelectric pump 21, and the second FET 62. Pressed.
  • the voltage drop in the first to fourth FETs 61 to 64 is negligibly small. Therefore, the output voltage Vo is determined by the partial pressure between the piezoelectric pump 21 and the resistor Rs.
  • FIG. 13 shows the relationship between the output voltage Vo and the temperature at different frequencies.
  • the graph Gs shows the case where the non-driving frequency f1 in the non-driving frequency band Fz which is the first frequency is 15 kHz
  • the graph Gt shows the case where the non-driving frequency f1 is 32 kHz
  • the graph Gv shows the case where the non-driving frequency f1 is 45 kHz
  • the graph Gw shows the relationship between the output voltage Vo and the temperature when the non-drive frequency f1 is 60 kHz.
  • the temperature of the piezoelectric pump 21 can be measured by reading the output voltage Vo by the control unit 15.
  • the voltage detection circuit 13 is, for example, a resistor Rs.
  • the output voltage Vo of the drive circuit 12 can be detected by detecting the voltage between the resistors Rs.
  • the difference between the input voltage Vc and the output voltage Vo is the applied voltage (drive voltage) of the piezoelectric pump 21.
  • the applied voltage in this specification is a voltage that is a difference between the input voltage input to the drive circuit 12 and the output voltage output from the drive circuit 12. Since the input voltage Vc is supplied from the power supply circuit 14 at a voltage value according to an instruction from the control unit 15, the fluctuation of the output voltage Vo corresponds to the applied voltage of the piezoelectric pump 21. Therefore, detecting the applied voltage of the piezoelectric pump 21 can be substituted by detecting the output voltage Vo.
  • the voltage detection unit of the present invention includes a voltage detection circuit 13 and a control unit 15.
  • the control unit 15 also corresponds to the control unit of the present invention.
  • the non-drive frequency f1 for determining the drive frequency fo is preferably higher because the impedance Z of the piezoelectric pump 21 is lower. For example, it is better to satisfy the following relational expression. f1> 1.2 ⁇ fo Expression (2)
  • FIG. 14 is a flowchart showing the flow of drive control of the pump device 11.
  • FIG. 15 is a graph showing an example of the relationship between time and the temperature of the piezoelectric pump in drive control.
  • FIG. 16 is a graph showing an example of the relationship between time and frequency in drive control.
  • the temperature of the piezoelectric pump increases with time by driving the piezoelectric pump 21.
  • the frequency of the voltage applied to the piezoelectric pump is changed as shown in FIG.
  • step S1 the drive circuit 12 applies a voltage to the piezoelectric pump 21 at the non-drive frequency fz1 in the non-drive frequency band Fz between the time t1 and the time t2 according to an instruction from the processing unit 16 of the control unit 15. .
  • the period from time t1 to t2 is, for example, 30 msec.
  • the piezoelectric pump 21 does not perform the pump operation because the voltage of the non-drive frequency fz1 is applied.
  • current flows through the piezoelectric pump 21 and the voltage detection circuit 13.
  • the control unit 15 detects the voltage Vo divided by the voltage detection circuit 13. In this case, the voltage Vo is an applied voltage applied to the piezoelectric pump 21.
  • step S3 the processing unit 16 checks the detected voltage Vo against a table stored in the storage unit 17, and determines the driving frequency fw1 in the driving frequency band Fw corresponding to the voltage Vo.
  • step S4 the processing unit 16 sends a drive signal to the gate of each FET to the drive circuit 12 at the determined drive frequency fw1.
  • the drive circuit 12 drives the piezoelectric pump 21 at the drive frequency fw1 between time t2 and time t3 according to the transmitted drive signal.
  • the period between the time t2 and the time t3 is, for example, 2.5 seconds. That is, the time during which the voltage is applied to the piezoelectric pump 21 at the non-driving frequency fz1 is much smaller than the driving time of the pump.
  • the piezoelectric pump 21 can be driven at a drive frequency fw2 lower than the drive frequency fw1 with respect to the temperature rise of the piezoelectric pump 21.
  • the piezoelectric pump 21 increases, the voltage applied to the piezoelectric pump 21 increases, so that the control unit 15 controls the driving frequency to decrease.
  • steps S1 to S4 are repeated. Since the temperature rise of the piezoelectric pump 21 is saturated after time t5, the driving frequency fw3 for driving the piezoelectric pump 21 is the same.
  • FIG. 17 is a graph showing the life of the battery that drives the pump device.
  • FIG. 18 is a graph showing the electrical efficiency of the pump device.
  • the graph Gk in the case where the driving frequency is controlled according to the temperature has a longer life of the driving battery for driving the piezoelectric pump 21 than the graph Gm in which the driving frequency is not controlled. I have.
  • the control of the driving frequency was not performed, the battery voltage dropped to 3 V or less around the time when the driving time exceeded 450 hours.
  • the drive frequency is controlled in accordance with the temperature, the battery voltage has 3.2 V or more even when the drive time exceeds 600 minutes.
  • the graph Gn in the case where the driving frequency is controlled according to the temperature shows that the electric efficiency is improved over the entire temperature range as compared with the graph Gp in which the driving frequency is not controlled. I have.
  • the electric efficiency increases in a lower temperature region and a higher temperature region than normal temperature.
  • the power consumption of the piezoelectric pump 21 can be reduced by changing the driving frequency according to the temperature.
  • the pump device 11 includes the piezoelectric pump 21, a voltage detecting unit configured to detect the applied voltage applied to the piezoelectric pump 21, the voltage detecting circuit 13 and the control unit 15, and the piezoelectric pump 21.
  • a control unit 15 that determines a drive frequency fo which is a second frequency among the above.
  • the piezoelectric pump 21 can be driven at an appropriate frequency corresponding to the temperature change of the piezoelectric pump 21. Thereby, the electric efficiency of the piezoelectric pump 21 can be improved. Further, since the second frequency may be a constant frequency, the driving frequency fo can be determined faster than scanning the frequency to detect the driving frequency fo. Therefore, it is particularly suitable for a pump device used in a milking machine that repeats pump driving and stopping operations.
  • the voltage detection circuit 13 is not limited to a resistor and may be an inductor as long as the voltage detection circuit 13 is configured by an impedance element.
  • FIG. 19 is a circuit diagram showing a modification of the drive circuit and the voltage detection circuit according to the first embodiment.
  • the voltage detection circuit 13a has an inductor L1.
  • the input voltage Vc from the power supply circuit 14 is applied to one end of the inductor L1.
  • the other end of the inductor L1 is connected to respective drains of the first FET 61 and the third FET 63.
  • the voltage detection circuit 13 a replaces the connection destination of the voltage detection circuit 13 from GND to the power supply circuit 14.
  • the voltage detection circuit 13a can obtain the input voltage Vo to the drive circuit 12 by dividing the voltage of the inductor L1 and the piezoelectric pump 21. Since the other end of the drive circuit 12 is connected to the ground, the input voltage Vo is the voltage applied to the piezoelectric pump 21.
  • the impedance element when the impedance element is connected to the power supply side of the drive circuit 12, if the voltage division ratio of the impedance element is too small, the impedance may exceed the input range of the output voltage detection circuit. In such a case, the voltage may be divided.
  • FIG. 20 is an explanatory diagram illustrating a flowing direction of a fluid according to the second embodiment.
  • FIG. 21 is a graph showing a relationship between time and pressure of the pump device according to the second embodiment.
  • the pump device 11 according to the first embodiment has been used as a suction device for the suction device 51.
  • the pump device 11 of the second embodiment is used as a pressurizing device of the pressurizer 52.
  • a fluid such as air flows from the piezoelectric pump 21 toward the cuff 53a for storing the fluid.
  • the valve 55 When the valve 55 is in the closed state, the fluid flows from the piezoelectric pump 21 toward the cuff 53a, so that the pressure in the cuff 53a gradually increases.
  • the valve 55 is opened, the fluid in the cuff 53a is released, and the pressure in the cuff 53a decreases.
  • Specific examples of the pressurizer 52 include a sphygmomanometer, a massager, a pMDI (pressurized @ Metered-Dose @ Inhaler), and a nebulizer.
  • the pump device 11 according to the second embodiment includes the same components as the pump device 11 according to the first embodiment. Therefore, the configuration of the pump device 11 according to the second embodiment other than the matters described below is common to the pump device 11 of the first embodiment.
  • the output of the piezoelectric pump 21 can be improved by changing the drive frequency in accordance with the temperature change.
  • the driving frequency is not changed in accordance with the temperature change, if the driving time of the piezoelectric pump 21 becomes longer, the temperature of the piezoelectric pump 21 increases due to self-heating. As a result, the pressure of the fluid discharged from the piezoelectric pump 21 cannot be increased.
  • the drive frequency is changed according to the temperature change, the pressure of the fluid discharged from the piezoelectric pump 21 can be increased even when the temperature of the piezoelectric pump 21 increases. As a result, uniform pressurization of the fluid can be realized.
  • the driving frequency is changed in accordance with the temperature of the piezoelectric pump, thereby making it possible to start the piezoelectric pump 21 at a low temperature. Also, the pressurizing capacity can be maintained during continuous operation.
  • FIG. 22 is a block diagram of a pump device according to the third embodiment.
  • the pump device 11a according to the third embodiment has a function of preventing the piezoelectric pump 21 from being damaged by self-heating.
  • an upper limit value of the output voltage Vo is stored in addition to the relationship between the output voltage Vo and the driving frequency fo.
  • the pump device 11 according to the first embodiment is different from the pump device 11a according to the third embodiment.
  • the configuration other than this point and the matters described below is common to the pump device 11 of the first embodiment and the pump device 11a of the third embodiment.
  • FIG. 23 is a flowchart showing the flow of drive control of the pump device 11a.
  • the drive control of the pump device 11a according to the third embodiment is performed after the drive control of the pump device 11 according to the first embodiment. Therefore, the drive frequency fo for driving the piezoelectric pump 21 is determined by the processing of steps S1 to S4 of the first embodiment. Therefore, in step S11, the drive circuit 12 drives the piezoelectric pump 21 at the determined drive frequency fo according to the drive signal sent from the processing unit 16.
  • step S12 the drive circuit 12 applies a voltage to the piezoelectric pump 21 at the non-drive frequency f1 in the non-drive frequency band Fz according to the instruction from the processing unit 16.
  • the piezoelectric pump 21 does not perform the pump operation because the voltage of the non-drive frequency f1 is applied. However, current flows through the piezoelectric pump 21 and the voltage detection circuit 13.
  • the control unit 15 detects the voltage Vo divided by the voltage detection circuit 13. In this case, the voltage Vo is an applied voltage applied to the piezoelectric pump 21.
  • the processing unit 16 compares the detected voltage Vo with the upper limit value stored in the storage unit 17. If the voltage Vo is lower than the upper limit value, as in Yes in step S13, the process returns to step S11. When the voltage Vo is not less than the upper limit value like No in Step S13, the control unit 15a lowers the driving of the piezoelectric pump 21 in Step S14.
  • step S11 the drive of the piezoelectric pump 21 can be reduced until the output voltage Vo of the drive circuit 12 becomes lower than the upper limit value.
  • the method of reducing the driving of the piezoelectric pump 21 is, for example, to reduce the input voltage Vc from the power supply circuit 14 to the drive circuit 12 according to an instruction from the control unit 15a. Further, the drive duty ratio of the drive signal from the processing unit 16 to each FET may be changed. Further, the drive frequency of the drive circuit 12 may be changed.
  • the piezoelectric pump 21 can be driven with an output voltage lower than the upper limit value corresponding to the temperature upper limit. Even in this case, the piezoelectric pump 21 can be prevented from being broken.
  • the voltage detection circuit 13 may be replaced with a voltage detection circuit 13b shown in FIG.
  • the voltage detection circuit 13b includes, in addition to the resistor Rs, a capacitor Cs having one end connected to each source of the second FET 62 and the fourth FET 64 and the other end connected to ground.
  • the capacitor Cs functions as a smoothing capacitor.
  • the frequency component of the output signal from the control unit 15 may be detected as noise at both ends of the resistor Rs.
  • the detection accuracy of the output voltage Vo can be improved.
  • an amplifier circuit 67 as shown in FIG. 25 may be connected between the I / O port 66 of the control unit 15 and one end of the resistor Rs (opposite the ground side).
  • the amplifier circuit 67 includes an amplifier Q, a resistor R1, a resistor R2, and a capacitor Csa.
  • the output voltage Vo is input to the non-inverting input terminal (+) of the amplifier Q, and one end of each of the resistors R1 and R2 is connected to the inverting input terminal (-).
  • the other end of the resistor R1 is connected to the ground.
  • the other end of the resistor R2 is connected to the output terminal of the amplifier Q.
  • the output terminal of the amplifier Q is connected to the I / O port 66 of the control unit 15.
  • a capacitor Csa is connected between the inverting input terminal ( ⁇ ) of the amplifier Q and the output terminal.
  • the voltage between the resistors Rs can be amplified and rectified by the amplifier circuit 67. Thereby, the S / N ratio of the output voltage can be improved, and the detection accuracy can be improved.
  • the control unit 15 may be connected to the A / D port instead of the I / O port 66.
  • FIG. 26 is an explanatory diagram illustrating a flow of a fluid in a pressurizer using the pump device according to the fourth embodiment.
  • FIG. 27 is a circuit diagram of a drive circuit and a voltage detection circuit according to the fourth embodiment.
  • two piezoelectric pumps 21 are arranged in parallel in the pressurizer 52 of the second embodiment.
  • the nozzle 71 and the piezoelectric pump 21 are connected instead of the container 53.
  • the discharge device 52a of the fourth embodiment does not include the valve 55 unlike the second embodiment because the nozzle 71 is open to the atmosphere.
  • the pump device 11 of the fourth embodiment is common to the pump device 11 of the second embodiment.
  • the drive control of the pump device 11 of the fourth embodiment is the same as that of the third embodiment.
  • Discharger 52a using the pump device according to the fourth embodiment is used for, for example, a nebulizer.
  • the piezoelectric pump 21 By connecting the piezoelectric pump 21 in parallel with the nozzle 71, the flow rate discharged from the nozzle 71 can be increased. Furthermore, since the piezoelectric pumps 21 are electrically connected in parallel, the output voltage Vo becomes relatively large due to the voltage division ratio with the voltage detection circuit. As a result, the measurement range is expanded, so that the detection accuracy of the output voltage Vo can be improved. Note that three or more piezoelectric pumps 21 may be connected in parallel.
  • the piezoelectric pump 21 is driven at less than the upper limit, so that the piezoelectric pump 21 can be prevented from being broken even when driven at full power.
  • it is suitable for use in places with low atmospheric pressure, such as high altitudes. In the case of high altitude, a failure due to excessive amplitude of the engine is likely to occur, but this can be prevented.
  • the drive circuit 12 in FIG. 27 further includes a fifth FET 65 for preventing a voltage from being applied to the voltage detection circuit during the pump operation.
  • the gate of the fifth FET 65 is connected to the control unit 15, the drain is connected to one end of the resistor Rs, and the source is connected to ground.
  • the fifth FET 65 functions as a switching element according to the drive signal from the control unit 15.
  • the voltage detection circuit is short-circuited because the fifth FET 65 is turned on.
  • the output voltage Vo becomes 0 [V], so that the electric efficiency can be further improved.
  • the non-drive frequency band Fz is a band lower than the resonance frequency fr and higher than or equal to the anti-resonance frequency fa, but is not limited thereto.
  • the non-drive frequency band Fz may be a band below a predetermined range from the resonance frequency fr and a band above a predetermined range from the anti-resonance frequency fa.
  • the non-drive frequency band Fz may be a band having a value lower than the resonance frequency fr by 20% or less than the resonance frequency fr and a band having a value higher than the anti-resonance frequency fa by 20% or higher than the anti-resonance frequency fa.
  • the shifted non-driving frequency band Fz is included in the non-driving frequency band Fz before the shift. Characteristics can be monitored accurately.
  • the temperature in a normal use state is, for example, in a range of ⁇ 10 ° C. to + 70 ° C.
  • the input voltage input from the power supply circuit 14 when detecting the divided output voltage Vo is a lower voltage than when the piezoelectric pump 21 is driven in the drive frequency band Fw. There may be. With this configuration, power consumption when detecting the output voltage Vo of the piezoelectric pump 21 can be reduced.
  • the present invention provides a piezoelectric pump, a voltage detection unit that detects an applied voltage applied to the piezoelectric pump, and the applied voltage at a first frequency outside a driving frequency band capable of driving the piezoelectric pump. And a control unit that drives the piezoelectric pump based on the control frequency and determines a second frequency in the drive frequency band.
  • a temperature-sensitive element such as a thermistor or a thermocouple around the piezoelectric pump, or to measure the temperature inside the pump. That is, if no temperature sensing element is provided, there is no other way but to measure the temperature inside the pump. Therefore, if the temperature characteristics of the piezoelectric pump are corrected without using a temperature-sensitive element such as a thermistor, it is considered that the possibility of using the present invention is high.
  • the present invention is applicable to a pump device including a piezoelectric pump.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)

Abstract

L'invention concerne un dispositif de pompe comprenant une pompe piézoélectrique, une unité de détection de tension qui détecte la tension appliquée à la pompe piézoélectrique, et une unité de commande qui détermine une seconde fréquence à l'intérieur d'une gamme de fréquences pilote qui commande la pompe piézoélectrique sur la base de la tension appliquée dans une première fréquence à l'extérieur de la gamme de fréquences pilote qui peut entraîner la pompe piézoélectrique.
PCT/JP2019/032422 2018-08-23 2019-08-20 Dispositif de pompe WO2020040131A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2018-156012 2018-08-23
JP2018156012 2018-08-23

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WO2020040131A1 true WO2020040131A1 (fr) 2020-02-27

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009158757A (ja) * 2007-12-27 2009-07-16 Sony Corp トランス、冷却装置及び電子機器
JP2009233515A (ja) * 2008-03-26 2009-10-15 Sony Corp 圧電素子の駆動装置、電子機器、および、圧電素子駆動周波数の制御方法
WO2013084709A1 (fr) * 2011-12-09 2013-06-13 株式会社村田製作所 Circuit d'attaque pour élément piézoélectrique
WO2017037117A1 (fr) * 2015-08-31 2017-03-09 Koninklijke Philips N.V. Capteurs en polymère électroactif et procédés de détection

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009158757A (ja) * 2007-12-27 2009-07-16 Sony Corp トランス、冷却装置及び電子機器
JP2009233515A (ja) * 2008-03-26 2009-10-15 Sony Corp 圧電素子の駆動装置、電子機器、および、圧電素子駆動周波数の制御方法
WO2013084709A1 (fr) * 2011-12-09 2013-06-13 株式会社村田製作所 Circuit d'attaque pour élément piézoélectrique
WO2017037117A1 (fr) * 2015-08-31 2017-03-09 Koninklijke Philips N.V. Capteurs en polymère électroactif et procédés de détection

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