JP2006118397A - Piezoelectric diaphragm pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce pulsation of delivered fluid by changing a control method of voltage applied on a piezoelectric element in a piezoelectric diaphragm pump. <P>SOLUTION: A diaphragm plate bends in a direction in which a space sucking and delivering fluid swells under an initial condition and fluid in the space is delivered by applying voltage on the piezoelectric element in this structure, and voltage apply on the piezoelectric element is controlled to keep voltage apply time (time t1 - time t3) for fluid delivery longer than voltage apply time (time t3 - time t4) for fluid suction. Consequently, the maximum value of instant flow rate in a delivery side becomes small and pulsation of delivery fluid is reduced as compared with that at a time that voltage apply time for suction and voltage apply time for delivery are equal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a diaphragm pump using a piezoelectric element.

  The conventional piezoelectric diaphragm pump sucks the working fluid from the suction side valve and discharges the working fluid from the discharge side valve as the deflection of the diaphragm plate increases and decreases, and the volume of the space inside the pump housing increases and decreases. . The increase / decrease in the deflection of the diaphragm plate is realized by deforming the piezoelectric element by applying a voltage to the electrodes provided on both sides of the disk-shaped piezoelectric element.

  In general, as a liquid discharge application by a pump, there is a supply of a small amount of alcohol to a fuel cell, supply of water to be electrostatically sprayed, or the like. In these applications, the liquid level and the surface position of the liquid at the discharge destination are important problems, so it is desirable that the flow rate of the discharged liquid be stable. However, since a reciprocating pump such as a diaphragm pump operates by alternately performing a suction stroke and a discharge stroke, the amount of pulsation generally increases.

  As a technique for reducing the amount of pulsation in this reciprocating pump, for example, as disclosed in Patent Document 1, in a plunger reciprocating liquid chromatograph pump, the liquid discharge stroke time of the plunger is compared with the liquid suction stroke time. Therefore, there is a plunger operation control means for shortening and reducing the pulsation of the liquid. In addition, as a prior art of this patent document 1, it is shown that the suction stroke time is shortened compared with the discharge stroke time in the liquid feed pump.

Although not a pump, for example, as disclosed in Patent Document 2, as a technique for reducing the pulsation of fluid flowing through a pipeline, an inverted signal having the same phase and the same amplitude as the fluid pulsation is output. In response to the inversion signal, the pressure adjusting member disposed in the fluid chamber into which the fluid in the pipeline is introduced is displaced so as to cause a pressure change that cancels the pulsation, and the pressure adjusting member is Static pressure reducing means for urging in a direction against static pressure is known.
JP-A 64-32163 JP-A-6-101793

  However, as shown in Patent Document 1, when the discharge stroke time is shortened, the pulsation is rather conspicuous in the diaphragm pump, and the prior art described in Patent Document 1 describes the cavitation in the plunger type pump. However, the present invention is not applied to a diaphragm type pump. Further, the technique disclosed in Patent Document 2 is not directly applicable to a diaphragm pump. The present invention has been made in view of the above problems, and an object of the present invention is to provide a piezoelectric diaphragm pump that can reduce pulsation of discharged fluid by changing a control method of a voltage applied to a piezoelectric element. To do.

  In order to achieve the above object, the invention of claim 1 is joined so as to cover a plate-shaped piezoelectric element, an electrode layer made of a conductive member disposed on one surface of the piezoelectric element, and the other surface of the piezoelectric element, A diaphragm plate made of a conductive member that can be elastically deformed in accordance with the deformation of the piezoelectric element, an insulating layer arranged to cover the opposite surface of the diaphragm plate to which the piezoelectric element is bonded, and an end of the diaphragm plate There is a space for compressing a fluid that is a gas or a liquid on the lower surface of the insulating layer, and a suction port that communicates with the space and sucks the fluid into the space, and discharges the fluid from the space. A piezoelectric diaphragm comprising: a housing having a discharge port for controlling the fluid; and a controller for controlling a suction time and a discharge time of the fluid by deforming the piezoelectric element by applying a voltage between the electrode layer and the diaphragm plate In the ram pump, the diaphragm plate is curved in a direction in which the space swells in an initial state where no voltage is applied due to bonding of the piezoelectric elements, and is configured to discharge fluid in the space by applying a voltage. Further, the control unit is set so that the voltage application time for fluid ejection is longer than the voltage application time for fluid suction.

  According to a second aspect of the present invention, in the first aspect of the present invention, the control unit is set such that a voltage applied at the time of ejection is an integrated waveform voltage.

  According to a third aspect of the present invention, in the first aspect of the present invention, the control unit is set such that a voltage applied at the time of ejection is a stepped step waveform voltage.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, the control unit is set such that a voltage to be applied at the time of ejection is a triangular waveform voltage.

  According to a fifth aspect of the present invention, in the first aspect of the present invention, the voltage applied at the time of discharge according to whether the pump is started or at a steady state, or according to the type of fluid, A circuit capable of switching to any one of a plurality of waveforms including an integrated waveform is provided.

  According to the first aspect of the present invention, since the fluid discharge time of the piezoelectric diaphragm pump becomes long, the voltage application time for fluid suction is equal to the voltage application time for fluid discharge when the discharge flow rate is constant. As compared with, the amount of pulsation of the discharge flow can be reduced by the increase of the discharge time. In diaphragm pumps, the operating frequency can be increased compared to plunger pumps, so even if the suction and discharge flow rate per stroke is small, the flow rate per hour can be as much as required for normal applications. Therefore, even if the amount of pulsation of inhalation increases, the occurrence of cavitation is small. Therefore, there is no problem even if the suction time is made relatively shorter than the discharge time.

  Further, in the piezoelectric diaphragm pump, the diaphragm plate is bent in a direction in which the space in the pump swells in an initial state where no voltage is applied, and is displaced so as to return to a flat state by applying a voltage from this state. This fluid is discharged, and the fluid is sucked when returning to the original state by the restoring force of the diaphragm plate itself. Here, since the discharge time during which the voltage is applied is longer than the suction time during which no voltage is applied, it is easy to reduce the pulsation on the discharge side.

  According to the second aspect of the present invention, deformation of the piezoelectric element with respect to voltage application occurs gradually, and the discharge flow rate of the fluid gradually increases without increasing rapidly. Therefore, when a rectangular waveform voltage is applied during discharge Compared with, the pulsation of the discharged fluid can be reduced.

  According to the invention of claim 3, the piezoelectric element is deformed stepwise with respect to the voltage application, the instantaneous discharge flow rate becomes smaller than when the direct discharge voltage is applied, and the pulsation of the discharge fluid can be reduced. it can.

  According to the fourth aspect of the present invention, the piezoelectric element is gradually deformed with respect to the voltage application, and the instantaneous discharge flow rate becomes average and the deviation from the average discharge flow rate becomes small. In comparison, the pulsation of the discharged fluid can be reduced.

  According to the invention of claim 5, it becomes possible to deal with a plurality of fluids having different viscosities without changing the structure, and at the start of the pump operation, a rectangular waveform voltage with good fluid conveyance efficiency is applied to the fluid discharge. The time can be shortened, and a discharge flow with less pulsation can be obtained using an applied voltage such as an integrated waveform in a steady state, and the effect of the invention of claim 1 can be obtained more efficiently.

  Hereinafter, a piezoelectric diaphragm pump according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic configuration of a piezoelectric diaphragm pump according to the present embodiment. The piezoelectric diaphragm pump is joined so as to cover the other surface of the piezoelectric element 1 by joining the plate-shaped piezoelectric element 1, the electrode layer 2 made of a conductive member disposed on one surface of the piezoelectric element 1, and the other surface of the piezoelectric element 1. Accordingly, the diaphragm plate 3 made of a conductive member that can be elastically deformed, the insulating layer 3a disposed so as to cover the surface opposite to the surface to which the piezoelectric element 1 of the diaphragm plate 3 is bonded, and the vicinity of the end of the diaphragm plate 3 A housing 5 having a space 4 for holding and compressing a gas or a fluid on the lower surface of the insulating layer 3a, a suction port 7c and a discharge port 7d communicating with the space 4, the electrode layer 2 and the diaphragm plate 3 A control unit 6 is provided that controls the suction / discharge time by deforming the piezoelectric element 1 by applying a voltage between the electrodes 10 connected to.

  In the present embodiment, a circular piezoelectric element (PZT) 1 is attached on a circular brass diaphragm plate 3, and the diaphragm plate 3 is made of a plastic, for example, polyacetal (POM) or polycarbonate (PC). ), Polyphenylstyrene (PPS) or the like. The dimensions of the piezoelectric element 1 are, for example, a diameter of 14 mm and a thickness of 0.13 mm, and the diaphragm plate 3 is a brass plate having a diameter of 20 mm and a thickness of 0.10 mm, for example.

  A suction valve 7a and a discharge valve 7b are connected to the suction port 7c and the discharge port 7d, respectively. These valves are arranged between the housing 5 and the valve presser 8. The structure of the valve portion is not limited in the present invention. For example, it is possible to use a rubber cantilever valve that opens and closes due to a pressure difference before and after the valve. The fluid to be sucked is sucked into the pump from the fluid container 12 through the suction pipe 11a through the suction port 7c. The fluid to be discharged is discharged from the discharge port 7d through the discharge pipe 11b.

  Further, in the manufacturing process of the piezoelectric diaphragm pump of the present embodiment, the piezoelectric element 1 is bonded (bonded) on the diaphragm plate 3. At this time, the diaphragm plate 3 is thermally contracted, and the diaphragm plate 3 is in a curved state. . In an initial state in which no voltage is applied to the piezoelectric element 1, the diaphragm plate 3 is fixed to the housing 5 so that the space 4 is in a bulging direction.

  2A and 2B are diagrams for explaining deformation of the piezoelectric element 1 due to voltage application. Here, the thickness direction of the piezoelectric element 1 is shown as the vertical direction, and + − indicates the polarization direction. By applying a voltage between the electrode layer 2 shown in FIG. 1 and the electrode 10 provided on the diaphragm plate 3, an electric field (open arrow) is generated in the thickness direction of the piezoelectric element 1. Deforms in the direction of the black arrow. When a positive voltage is applied and the direction of the electric field is the same as the direction of polarization of the piezoelectric element 1 as shown in FIG. 2A, the piezoelectric element 1 extends in the thickness direction and contracts in the radial direction. In contrast, when a negative voltage is applied and the direction of the electric field is opposite to the direction of polarization of the piezoelectric element 1 as shown in FIG. 2B, the piezoelectric element 1 contracts in the thickness direction and extends in the radial direction.

  3A and 3B show the operation of the piezoelectric diaphragm pump according to the present embodiment. In the diaphragm pump, when a positive voltage is applied from the initial state where no voltage is applied as shown in FIG. 1, the piezoelectric element 1 is contracted in the radial direction, but the diaphragm plate 3 is not expanded. As the piezoelectric element 1 is deformed, the deflection of the diaphragm plate 3 is reduced. As a result, the volume of the space 4 formed by the insulating layer 3a and the housing 5 is reduced, the pressure in the space 4 is increased, the suction valve 7a is closed, the discharge valve 7b is opened, and the discharge stroke is started. The fluid is discharged from 7d.

  If the applied voltage is the ground voltage from the state where the positive voltage is applied as described above, the diaphragm plate 3 returns to the initial shape by the restoring force of the diaphragm plate 3 itself as shown in FIG. That is, as the deflection of the diaphragm plate 3 increases, the volume of the space 4 increases and the pressure in the space 4 decreases, the discharge valve 7b closes, the suction valve 7a opens, and the suction stroke starts. Inhale fluid.

  Here, when the applied voltage is an alternating voltage of a positive voltage and a ground voltage, the diaphragm plate 3 vibrates in the thickness direction, and the pump repeats the discharge stroke and the suction stroke alternately. When the frequency of the alternating voltage (driving frequency) is low, the piezoelectric element 1 deforms abruptly when a voltage for ejection is applied. Therefore, the fluid to be ejected has the highest flow rate immediately after application of the voltage, and the pump is pumped by ejection. As the internal fluid decreases, the instantaneous flow rate gradually decreases and converges to almost zero. Thereafter, when the applied voltage becomes the ground voltage, the suction stroke starts, and the instantaneous suction amount of the fluid is greatest at the moment when the applied voltage is the ground voltage, and then gradually decreases, as in the discharge stroke.

  When the drive frequency is increased, a reverse voltage is applied at the moment when the instantaneous suction flow rate or discharge flow rate decreases to zero. In this case, the flow rate of the fluid flowing through the pump becomes the largest. When the driven fluid is water, the fluid flow rate becomes the highest at a driving frequency of about 40 Hz. If the drive frequency is higher than the above, the suction stroke starts before the instantaneous discharge flow rate becomes zero in the discharge stroke. At this time, the flow rate of the fluid flowing through the pump is smaller than in the above case, and the flow rate expected by the applied voltage is not ensured.

  Next, examples of voltage waveforms applied to the piezoelectric element 1 will be described with reference to FIGS.

  FIG. 4 schematically shows the waveform of the applied voltage in Example 1 according to the invention of claim 1 and the flow rate of the fluid flowing through the pump at the same time. In this embodiment, the applied voltage is an alternating voltage of +120 V and 0 V, and a voltage with a duty ratio (positive voltage application time ratio) of 70% as shown by a solid line in FIG. 4 is used. In FIG. 4, the pump starts the discharge stroke when a voltage of +120 V is applied at time t1, and the pump starts the suction stroke when a voltage of 0 V is applied at time t3. When the frequency of the alternating voltage to be applied is 100 Hz, the suction voltage application time shown from time t3 to time t4 in FIG. 4 is 3 ms. The discharge voltage (0V) application time shown from time t1 to time t3 is 7 ms. By setting conditions such that discharge is completely completed within this time, the average flow rate of the pump becomes the largest, so the maximum flow rate And the average flow rate becomes the smallest, and the pulsation of the discharge flow can be reduced.

  The condition for this is, for example, that the flow path resistance on the discharge side is made larger than that on the suction side so that the time required to completely discharge the fluid coincides with the voltage application time, and the flow path resistance on the suction side is reduced. The time required for inhalation can be set to coincide with the voltage application time. At this time, the suction flow waveform is as shown by the solid line in FIG. 4, and the instantaneous suction flow that becomes maximum at time t3 is the maximum at time t2 when the duty ratio is 50% as shown by the broken line. Although larger than the suction flow rate, the suction side pulsation does not affect the discharge side pulsation. Moreover, in the diaphragm pump, since the operating frequency can be made higher than that of a plunger type pump, even if the suction and discharge flow rate per time is small, the flow rate per time is, for example, a liquid spray device, etc. The required amount for normal use such as supplying liquid to the tube can be obtained, and even if the amount of pulsation of inhalation increases, the occurrence of cavitation is small. Therefore, there is no problem even if the suction time is made relatively shorter than the discharge time.

  FIG. 5 schematically shows the waveform of the applied voltage in Example 2 according to the invention of claim 2 and the flow rate of the fluid flowing through the pump at the same time. In this embodiment, the applied voltage is an alternating voltage of +120 V and 0 V, and is an integrated waveform voltage as shown by a solid line in FIG. Such a waveform can be realized, for example, by inserting an appropriate resistance between the high voltage and the piezoelectric element electrode during voltage application, or by controlling the applied voltage with a transistor, but the implementation means is not limited to this. . When the application voltage having a rectangular waveform is used, there is a problem that the instantaneous flow rate immediately after the discharge becomes large, but in this embodiment, as shown by the solid line in FIG. 5, the voltage applied during the discharge from time t1 to time t3 is continuous. Therefore, the piezoelectric element is gradually deformed with respect to voltage application, so that the discharge flow rate gradually increases without increasing rapidly. The period from time t3 to time t4 is the suction voltage application time. Thus, since the maximum value of the instantaneous discharge flow rate is smaller than when the applied voltage having the rectangular waveform is used, the pulsation of the discharge flow is reduced. Moreover, since the time ratio during which the discharge voltage is applied is large, the final discharge flow rate is the same as that when the rectangular voltage is applied.

  FIG. 6 shows the waveform of the applied voltage in Example 3 according to the invention of claim 3 and the flow rate of the fluid flowing through the pump at the same time. In this embodiment, the suction voltage is set to 0V and the discharge voltage is set to + 120V. In a state where the applied voltage before time t1 in FIG. 6 is 0V, + 60V is applied as an intermediate voltage between the suction voltage and the discharge voltage from time t1, and then the applied voltage is increased to + 120V from time t2. That is, a stepped waveform voltage is applied during ejection. Since the deformation amount from the initial state of the piezoelectric element 1 at time t1 is smaller than when a voltage of +120 V is applied at time t1, as shown by the solid line in FIG. 6, an instantaneous discharge flow rate of +120 V was applied. Less than when. By maintaining this steady state for a certain period of time from time t1 to time t2, the instantaneous flow rate gradually decreases during this time. After that, the deformation of the piezoelectric element 1 when +120 V is applied from time t2 becomes the deformation amount from the state when +60 V is applied, so that the instantaneous discharge flow rate is also smaller than when +120 V is applied immediately from 0 V. As a result, by inserting a potential between the suction voltage and the discharge voltage during the discharge stroke, the maximum value of the instantaneous discharge flow rate becomes smaller than when the applied voltage having a rectangular waveform is used. The pulsation will decrease.

  FIG. 7 schematically shows the waveform of the applied voltage in Example 4 according to the invention of claim 4 and the flow rate of the fluid flowing through the pump at the same time. In this embodiment, the applied voltage is an alternating voltage of +120 V and 0 V, and is a triangular waveform voltage as shown by the solid line in FIG. Such a waveform can be realized, for example, by amplifying the voltage with a transistor or an operational amplifier, but the realization means is not limited to this. When a voltage having a rectangular waveform is applied during discharge, there is a problem that the instantaneous discharge flow rate immediately after discharge is large. However, by increasing the voltage applied during discharge from time t1 to t2, the piezoelectric element 1 is moderated. Therefore, the instantaneous discharge flow rate can be averaged, and the deviation from the average flow rate is also reduced. That is, since the maximum value of the instantaneous discharge flow rate is smaller than when a rectangular waveform applied voltage is used, the pulsation of the discharge flow is reduced. Moreover, since the time ratio during which the discharge voltage is applied is large, the final discharge flow rate is the same as that when the rectangular voltage is applied.

  FIG. 8 schematically shows a circuit diagram and a waveform of an applied voltage in the fifth embodiment according to the invention of claim 5. In the present embodiment, as the waveform of the applied voltage, the control unit 6 that can switch between a rectangular waveform as shown in FIG. 8B and an integrated waveform as shown in FIG. 8C is provided. As illustrated in FIG. 8A, the control unit 6 includes a switch SW that switches a path (Y) in which the resistor R is inserted and a path (X) in which the resistor R is not inserted, and the switch SW and the voltage application time. And a part (Z) for controlling the. When a voltage having a rectangular waveform is applied, fluid pulsation is generally large but flow rate is large. On the other hand, when an integral waveform voltage is applied, the flow rate is small but the pulsation is small. Therefore, when the fluid is sent to the tip of the discharge port 7d at the start of the pump start, there is no influence of the pulsation on the discharge flow, so the applied voltage of the rectangular waveform having a high suction efficiency shown in FIG. After the operation and the fluid starts to be discharged from the discharge port 7d (steady state), the pulsation of the discharge flow is reduced in the steady state by switching to the applied voltage of the integral waveform shown in FIG. 8C. it can.

  FIG. 9 schematically shows a circuit diagram and a waveform of an applied voltage in Example 6 according to the invention of claim 5. In the present embodiment, as the waveform of the applied voltage, the control unit 6 capable of switching between an integrated waveform with a high voltage rising speed as shown in FIG. 9B and an integrated waveform with a low voltage rising speed as shown in FIG. 9C. have. As illustrated in FIG. 9A, the control unit 6 includes a switch SW that switches a path (X) in which the resistor R is inserted and a path (Y) in which the two resistors R are inserted, and the switch SW. And a portion (Z) for controlling the voltage application time. According to such a configuration, when the pump is used as a fluid having different viscosities, for example, for discharging oil (viscosity 0.02) and water (viscosity 0.001 Pa · s), the viscosities differ by 20 times. When controlled with the same voltage waveform, the flow rate differs between oil and water, but by switching the switch SW and changing to the voltage rise rate of the integral waveform that matches the viscosity of the fluid, the structure such as the flow path diameter of the pump It becomes possible to cope with a plurality of types of fluids without changing. In addition, FIG.9 (b) is a voltage waveform for oil, (c) is a voltage waveform for water.

  FIG. 10 shows a schematic configuration of the piezoelectric diaphragm pump according to the seventh embodiment. In the seventh embodiment, the flow rate sensor 13 for measuring the fluctuation of the discharge flow rate from the pump is arranged in the vicinity of the discharge port 7d of the discharge pipe 11b in the first to fourth embodiments. The suction voltage application time and the discharge voltage application time are feedback-controlled based on the value from the flow sensor 13. Other configurations are the same as those shown in FIG.

  In this embodiment, when the flow rate value measured by the flow rate sensor 13 becomes larger than the set value, the control unit 6 decreases the total flow rate by shortening the suction voltage application time. When the flow rate is smaller than the set value, the control unit 6 increases the total flow rate by extending the voltage application time for suction. Although the voltage application time ratio of suction and discharge can be arbitrarily changed, it is desirable to set the time ratio of the discharge application voltage in a large range in order to reduce the pulsation of the discharge flow. In this way, since the suction and discharge voltage application time ratio is feedback controlled while measuring the discharge flow rate, it becomes possible to secure a stable set flow rate while reducing the pulsation of the discharge flow, and the suction voltage application time Therefore, it is possible to prevent a decrease in the flow rate due to the fact that the fluid cannot be completely sucked due to the shortage of the fluid.

  FIG. 11 shows a schematic configuration of the piezoelectric diaphragm pump according to the eighth embodiment. In the eighth embodiment, the flow rate sensor 14 for measuring the fluctuation of the suction flow rate from the fluid container 12 is disposed in the vicinity of the suction port 7c of the suction pipe 11a in the first to fourth embodiments, and the control unit 6, feedback control of the suction voltage application time is performed based on the value of the flow sensor 14. Other configurations are the same as those shown in FIG.

  In the present embodiment, when the flow rate value measured by the flow rate sensor 14 becomes larger than the set value, the control unit 6 decreases the total flow rate by shortening the suction voltage application time. When the flow rate is smaller than the set value, the control unit 6 increases the total flow rate by extending the voltage application time for suction. This control does not affect the pre-optimized discharge flow pulsation reduction conditions. In order to reduce the pulsation of the discharge flow, it is desirable to set the voltage application time ratio between suction and discharge in the same manner as in the seventh embodiment. As described above, since the voltage application time is feedback-controlled while measuring the suction flow rate, it is possible to prevent a decrease in the flow rate due to the shortage of the suction voltage application time and the inability to completely suck the fluid. In addition, it is possible to secure the suction amount (discharge amount) without changing the optimization condition for reducing the pulsation of the discharge flow rate.

  12 and 13 schematically show the waveform of the applied voltage in Example 9. FIG. In the present embodiment, in the configuration of the above-described eighth embodiment, an integrated waveform including a steady voltage region as shown in FIGS. 12 and 13 is based on the maximum flow rate value from the flow rate sensor 14 in the control unit 6. Feedback control is performed on the time during which the applied voltage is a steady voltage. FIG. 12 shows a case where the steady voltage time is shortened, and FIG. 13 shows a case where the steady voltage time is lengthened. In any case, the discharge voltage application time is from time t1 to time t3, the suction voltage application time is from time t3 to time t4, the suction voltage is set to 0V, the discharge voltage is set to + 120V, and the suction voltage is set. + 60V is set as a steady voltage intermediate between the discharge voltage and the discharge voltage, the voltage is increased with an integrated waveform from time t1, and the applied voltage + 60V is steady until a time t2-2 a predetermined time after time t2-1. From -2, increase the applied voltage to + 120V again with the integrated waveform.

  In this embodiment, when the maximum value of the instantaneous flow rate measured by the flow rate sensor 14 becomes larger than the set value, the control unit 6 makes a steady state from time t2-1 to time t2-2 as shown in FIG. By increasing the voltage application time, the total flow rate of the pump can be reduced. Conversely, when the maximum value of the flow rate becomes smaller than the set value, the application time of the steady voltage is reduced as shown in FIG. By shortening, the flow rate can be increased. The flow rate adjustment by controlling the steady voltage application time can be set independently of the conditions for reducing the pulsation, and the set flow rate can be secured stably while maintaining the optimum discharge conditions. In addition, since an intermediate potential between the suction voltage and the discharge voltage is inserted between the discharge strokes, and the voltage is applied with an integral waveform, the pulsating flow reducing effect can be obtained as in the third embodiment, and the piezoelectric Since the element is gradually deformed step by step, the piezoelectric element can be prevented from being excessively deformed.

  In addition, this invention is not limited to the structure of the said embodiment, A various deformation | transformation is suitably possible in the range which does not change the scope of the invention. For example, the voltage applied for inhalation may be a negative voltage. In addition, even when the direction of polarization of the piezoelectric element is reversed, a completely equivalent operation can be realized by setting the voltage applied to the piezoelectric element to a negative voltage or reversing the direction of applying the voltage to the piezoelectric element.

The figure which shows schematic structure of the piezoelectric diaphragm pump by embodiment of this invention. (A) is a figure which shows operation | movement when a positive voltage is applied to the piezoelectric element used for a piezoelectric diaphragm pump same as the above, (b) is a figure which shows operation | movement when a negative voltage is applied to the piezoelectric element. It is a figure which shows operation | movement of the piezoelectric diaphragm pump by embodiment of this invention, (a) is a figure which shows the state which applied the voltage of discharge, (b) is a figure which shows the state which applied the voltage of inhalation. FIG. 3 is a diagram for explaining control of the piezoelectric diaphragm pump according to the first embodiment. FIG. 6 is a diagram for explaining control of a piezoelectric diaphragm pump according to a second embodiment. FIG. 6 is a diagram for explaining control of a piezoelectric diaphragm pump according to a third embodiment. FIG. 6 is a diagram for explaining control of a piezoelectric diaphragm pump according to a fourth embodiment. (A) is a circuit diagram for controlling the piezoelectric diaphragm pump according to the fifth embodiment, and (b) and (c) are diagrams for explaining the control. (A) is a circuit diagram for controlling the piezoelectric diaphragm pump according to the sixth embodiment, and (b) and (c) are diagrams for explaining the control. FIG. 10 is a diagram illustrating a schematic configuration of a piezoelectric diaphragm pump according to a seventh embodiment. FIG. 10 is a diagram illustrating a schematic configuration of a piezoelectric diaphragm pump according to an eighth embodiment. FIG. 10 is a diagram for explaining control of a piezoelectric diaphragm pump according to a ninth embodiment. The figure explaining control of a piezoelectric diaphragm pump same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Electrode layer 3 Diaphragm plate 3a Insulating layer 4 Space 5 Case 6 Control part 7c Inlet 7d Inlet

Claims (5)

A flat plate-shaped piezoelectric element, an electrode layer made of a conductive member disposed on one surface of the piezoelectric element, and a conductive member bonded so as to cover the other surface of the piezoelectric element and elastically deformable according to the deformation of the piezoelectric element A diaphragm plate, an insulating layer disposed so as to cover a surface opposite to a surface to which the piezoelectric element of the diaphragm plate is bonded, and a vicinity of an end portion of the diaphragm plate, and a gas or A housing having a space for compressing a fluid made of a liquid, a suction port that communicates with the space and sucks the fluid into the space, and a discharge port that discharges the fluid from the space; and the electrode layer A piezoelectric diaphragm pump comprising: a control unit for controlling the suction time and the discharge time of the fluid by deforming the piezoelectric element by applying a voltage between the diaphragm plate and the diaphragm plate;
The diaphragm plate is curved in a direction in which the space swells in an initial state where no voltage is applied due to bonding of the piezoelectric elements, and is configured to discharge a fluid in the space by applying a voltage.
The piezoelectric diaphragm pump characterized in that the control unit is set so that a voltage application time for fluid ejection is longer than a voltage application time for fluid suction.   2. The piezoelectric diaphragm pump according to claim 1, wherein the control unit is configured such that a voltage to be applied at the time of discharge is set to an integral waveform voltage.   2. The piezoelectric diaphragm pump according to claim 1, wherein the control unit is configured such that a voltage to be applied at the time of discharge is set to a voltage having a stepped step waveform.   2. The piezoelectric diaphragm pump according to claim 1, wherein the controller applies a voltage applied at the time of discharge to a triangular waveform voltage. The control unit can switch the voltage applied at the time of discharge to one of a plurality of waveforms including a pulse waveform and an integrated waveform, depending on whether the pump starts or is in a steady state, or depending on the type of fluid The piezoelectric diaphragm pump according to claim 1, further comprising:

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