JPH0354383A - Piezoelectric pump - Google Patents

Abstract

PURPOSE:To obtain a sufficient delivery amount by dividing an electrode of piezoelectric vibrating plate into a central part side and a peripheral part side, supported by a pump main unit side, and providing a driving means which applies AC voltage, with polarity inverted to each other, to each electrode in the central part side and the peripheral part side. CONSTITUTION:When AC voltage from a power supply 23 is applied to a bimorph vibrator 13 of a piezoelectric actuator 3, the voltage is applied, with a phase left as not changed, to a peripheral part 19, that is, between a peripheral electrode 17 and a metal plate 16, and, with polarity in a reverse direction to the peripheral part 20, to a central part 19, that is, between a central electrode 18 and the metal plate 16 through an inverter 25. Since the vibrator 13 is different in the direction of deflection by the direction of a potential difference between each electrode 17, 18 and the metal plate 16, when the central part 19 is deflected to a side of a pump chamber 5, the peripheral part 20 is deflected in the reverse direction to the central part side, but because the peripheral part 20 is deflected with a supporting fixed part with a pump main unit 2 serving as a supporting point, the central part 19 is deflected so as to be lifted to a side of the pump chamber 5. When a phase of voltage advances 180 deg., the deflection is reversed to the above described. That is, the displacement of the vibrator 13 is increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used as a pump, for example, when administering medicine by inserting it into a living body, and the internal volume of the pump chamber is reduced by the vibration of a piezoelectric diaphragm. This invention relates to a piezoelectric pump that performs a pumping action by changing the

[Prior Art] Conventionally, there are piezoelectric pumps disclosed in Japanese Patent Application Laid-Open No. 61-53476 and Japanese Utility Model Application No. 57-30394. In these conventional piezoelectric pumps, at least one inner surface portion of the pump chamber is formed by a piezoelectric diaphragm such as a unimorph vibrator or a bimorph vibrator.

Furthermore, check valves are provided at the suction port and the discharge port of the pump chamber, respectively.

By applying a voltage to the electrodes of the piezoelectric diaphragm, the piezoelectric diaphragm is displaced and the internal volume of the pump chamber is changed, so that fluid is sucked in from the suction port and discharged from the discharge port. .

[Problems to be Solved by the Invention] However, the piezoelectric diaphragm in the conventional piezoelectric pump has one electrode provided on each surface thereof. Therefore, when a voltage is applied to the electrode, the diaphragm of the piezoelectric diaphragm only bends in one direction depending on its polarity.

Furthermore, since the peripheral portion of the piezoelectric diaphragm is fixed and restrained to a member on the pump main body side over its entire periphery, bending motion in the peripheral portion of the piezoelectric diaphragm is restricted. Therefore, the amount of displacement of the piezoelectric diaphragm becomes smaller. In other words, there was a problem in that a sufficient discharge flow rate could not be obtained.

The present invention has been made in view of the above-mentioned problems, and its purpose is to create an efficient piezoelectric pump that has a large displacement amount of the piezoelectric diaphragm compared to its size and can obtain a sufficient discharge amount. Our goal is to provide the following.

[Means for Solving the Problems and Effects] In order to solve the above problems, the present invention comprises at least one inner surface of the pump chamber formed in the pump body with a piezoelectric diaphragm, and the piezoelectric vibrations are temporarily applied with a voltage. In a piezoelectric pump that sucks in and discharges fluid by displacing a piezoelectric diaphragm and changing the internal volume of the pump chamber, the electrodes of the piezoelectric diaphragm are supported on the center side and the pump body side. The device is divided into a peripheral portion and is provided with a driving means for applying alternating current voltages having opposite polarities to each electrode on the central portion side and the peripheral portion side.

However, since the piezoelectric diaphragm is driven by applying alternating current voltages with different polarities to the electrodes in the central and peripheral areas, the amount of displacement of the piezoelectric diaphragm can be increased even when restrained and supported at the periphery. The displacement of the piezoelectric diaphragm per cycle of the applied alternating current voltage increases the discharge flow rate, making it possible to obtain sufficient discharge.

[Embodiment] FIGS. 1 to 6 show a first embodiment of the present invention.

FIG. 1 is a diagram showing the overall structure of a piezoelectric pump 1. As shown in FIG.

That is, this piezoelectric pump 1 has a piezoelectric actuator 3 provided in the lower part of its pump body 2, and the peripheral portion of the piezoelectric actuator 3 is pressed and fixed against the pump body 2 by a suppression ring 4, and is supported in a liquid-tight manner. There is. An opening 2a that opens toward the lower surface is formed in the lower part of the pump body 2, and a piezoelectric actuator 3 is installed in this opening 2a.

The lower surface of the piezoelectric actuator 3 has an opening 2a thereof.
It is open to the outside. In addition, piezoelectric actuator 3
partitions the opening 2a, and forms a sealed pump chamber 5 facing the inner wall of the pump body 2 on the upper surface side and between the inner wall and the inner wall. In other words, the piezoelectric actuator 3 is connected to one of the pump chambers 5.
It forms the bottom surface.

The pump body 2 is formed with an inlet 6 and a discharge port 7 that communicate with the pump chamber 5. An inflow mouthpiece 8 is attached to this inflow port 6 . Further, a discharge mouth metal 9 is attached to the discharge D7. Furthermore, an inflow valve 11 made of a check valve is provided at the inflow port 6 to allow the flow to flow only toward the inflow side.

Further, the discharge port 7 is provided with a discharge valve 12 consisting of a check valve, so that the fluid flows only toward the discharge side.

FIG. 2 shows the detailed structure of the piezoelectric actuator 3. That is, the piezoelectric actuator 3 includes, for example, a bimorph vibrator 13 as a piezoelectric diaphragm and a first insulating layer 14.
and a second insulating layer 15 to form a single plate.

The bimorph resonator 13 is made up of two ceramic plates made of PZT (lead zirconium titanate), etc., which are bonded together with a metal plate 16 sandwiched between them, and electrode layers are formed on both the top and bottom surfaces by Al vapor deposition or the like. . This electrode layer is divided into a peripheral electrode 17 and a central electrode 18,
The central electrode 1z and one peripheral electrode are electrically isolated from each other.

That is, the electrode layer of the bimorph vibrator 13 is divided into one peripheral part used for fixing to the pump body 2 and a central part 20 as a free side part. And the center electrode IS
and the metal plate 16, and the peripheral electricity? A first control line 21 and a second control line 22 are separately connected between the pole 1@ and the metal plate 16, respectively, for applying a driving AC voltage. Peripheral electrode】7
A driving AC voltage can be applied to the center electrode 18 and the center electrode 18 individually.

This bimorph resonator 13 is driven by a drive system as shown in FIGS. 3 and 4. That is, it consists of a power source 23 and a control section 24 that sets the driving AC voltage of the power source 23 to a desired voltage value and frequency value, and sets the driving AC voltage of the power source 23 to a desired voltage value and frequency value.
After setting the frequency value, each electrode 17, 18 in the central part 2o and peripheral part 21 of the bimorph resonator 13
The configuration is such that each is applied separately. Furthermore, at this time, the peripheral portion 19 of the electrode layer in the bimorph resonator 13
An inverter 25 is provided between the and the control unit 24 to compare the phase of the driving AC voltage applied to the peripheral part 19 of the electrode layer in the bimorph oscillator 13 with the phase of the driving AC voltage applied to the central part 20. It is now possible to change it by 180@.

Next, the operation of the piezoelectric pump 1 having the above configuration will be explained. That is, when a driving AC voltage is applied to the bimorph vibrator 13 in a drive circuit configured as shown in FIGS. 3 and 4, the phase of the applied voltage is 180' between one peripheral part and the central part 20. Since they are different, they operate in the opposite drive state.

That is, when applying the AC voltage from the power source 23 to the bimorph resonator 13 as shown in FIG. Apply it as is. On the other hand, the polarity is applied to the peripheral portion 19 , that is, between the peripheral electrode 17 and the metal plate 16 through an inverter 25 with a polarity opposite to that applied to the central portion 20 . That is, voltages with phases shifted by 180'' are applied to each electrode 17, 18.

Therefore, the bimorph resonator 13 bends in a different direction depending on the direction of the potential difference generated between the electrodes 17 and 18 and the metal plate 16. Therefore, when the central portion 20 is bent so as to bulge toward the pump chamber 5 as shown in FIG. 5(a),
The peripheral portion 19 deflects in the opposite direction to its central portion 20. However, since the peripheral portion 19 bends using the supporting and fixed portion with the pump body 2 as a fulcrum, it bends so as to lift the central portion 20 toward the pump chamber 5 side.

FIG. 6 shows the state when the phase of the applied voltage is advanced by 180'. In other words, contrary to the case shown in FIG.
0 is bent so as to bulge outward from the opening 2a.

Due to this action, the piezoelectric pump 1 as a whole operates as follows. Bimorph oscillator 13 is in opening 2a
It bends to the side, the volume inside the pump chamber 5 increases, and the pump chamber 5
When the internal pressure decreases, the inflow valve 11 of the inlet 6 opens and fluid flows into the pump chamber 5. Moreover, when the bimorph resonator 13 bends toward the pump chamber 5 in the opposite direction, the volume within the pump chamber 5 decreases and the pressure within the pump chamber 5 increases. For this reason,
As the inflow valve 6 closes, the discharge valve 12 opens to discharge fluid from the pump chamber 5. By repeating this, a pumping action is performed to take fluid in from the inlet 6 and sequentially send it out to the discharge port 7.

With the above configuration, the bimorph resonator 13 has a peripheral portion 19
Since the central portion 20 is lifted up, the amount of displacement of the vibrator 13 increases accordingly. therefore,
Sufficient discharge volume was obtained and efficiency improved.

Further, since the bimorph resonator 13 has the above configuration, the mechanical strength of the bimorph resonator 13 is uniform. Therefore, when operated, the bimorph oscillator 1
The displacement amount of 3 becomes sufficiently large even when the load applied to the pymorph vibrator 13 is large. Therefore, it is now possible to obtain a sufficient discharge amount even when the load is large.

In addition, since the amount of displacement of the bimorph vibrator 13 when the same alternating current voltage is applied is large, the flow rate can be controlled over a wide range and finely controlled.

FIG. 7 shows a second embodiment of the invention. In this embodiment, a drive system is constructed in which separate control sections 31 and 32 are provided on the first control line 21 side and the second control line 22 side. That is, the AC voltage applied to the bimorph resonator 13 from the power supply 23 is divided into an AC voltage applied to the peripheral part 19 side and an AC voltage applied to the central part 20 side, and the AC voltage applied to the peripheral part 19 side is divided into AC voltage applied to the peripheral part 19 side and AC voltage applied to the central part 20 side. is applied through the first control section 31 after shifting its phase by 180'' by the inverter 33, and the AC voltage applied to the central portion 2o side is applied as is through the second control section 32.

In other words, the phase between the peripheral electrode 17 and the center electrode 18 is set to 180.
'Staggered driving AC voltages can be applied individually.

Therefore, the first control section 31 and the second control section 32 can independently control the driving AC voltage applied to the peripheral part 19 side and the driving AC voltage applied to the central part 20 side. For this reason, for example, if the diameter of the tube connected to the outlet fitting 9 on the outlet 7 side is smaller than the diameter of the tube connected to the inlet fitting 8 on the inlet 6 side, or if the diameter of the tube connected to the outlet fitting 9 on the side of the inlet 6 is smaller, or When the load is large, such as when bending the actuator in the opposite direction, the bimorph oscillator 13 can be sufficiently displaced by making the AC voltage applied to the peripheral part 19 larger than that to the central part 20. can be done. therefore,
According to this embodiment, the pump becomes more powerful than that of the first embodiment and can obtain a larger injection pressure. Furthermore, since the amount of displacement of the bimorph vibrator 13 also increases, the flow rate control range is wider and narrower control is possible.

Furthermore, the piezoelectric actuator 3 may be configured using a monomorph vibrator instead of the bimorph vibrator 13.

8 to 13 show a third embodiment of the present invention.

In this third embodiment, the bimorph resonator 13 is constructed as shown in FIG. That is, bimorph oscillator 1
A peripheral electrode 17 is provided at each end edge portion in the longitudinal direction in 3, and this portion is defined as a supporting side peripheral portion 19. Further, a central electrode 18 electrically separated from the peripheral electrodes 17 is provided at a central portion sandwiched between the peripheral electrodes 17 . This portion of the center electrode 18 is defined as a center portion 20. Furthermore, the bimorph resonator 13 is molded with an insulating cover 35.

9 to 13 show the state of the structure in which the piezoelectric actuator 3 having the above structure is supported on the pump body 2. FIG. That is, the entire peripheral edge of the piezoelectric actuator 3 is tightly fitted into and supported by a support groove 41 formed on the inner surface of the opening 2a in the pump body 2.

Furthermore, each longitudinal edge of the piezoelectric actuator 3, including the edge portion 13a of the bimorph vibrator 13, is fitted into the support groove 41 and supported, as shown in FIGS. 9 and 10. There is. In addition, each of the left and right edges 13a in the direction orthogonal to the longitudinal direction of the piezoelectric actuator 3 has an eleventh
As shown in Fig. 12, the bimorph oscillator 1
It is fitted and supported within the support groove 41 within a range where the portion 3 is not covered. In other words, each of the left and right edges 13a in the direction orthogonal to the longitudinal direction of the piezoelectric actuator 3 is
Only the insulating layer 14 and the second insulating layer 15 are fitted into the supporting groove 41 and supported.

Therefore, in this orientation, the bimorph resonator 13 is not directly supported but indirectly supported via the insulating layers 14 and 15, so that the bimorph resonator 13 has a free periphery 42.

Moreover, FIG. 13 shows the support relationship of the piezoelectric actuator 3 seen from the plane. In FIG. 13, the bimorph oscillator 13 is indicated by a dotted line (partially indicated by a solid line). The shaded area is a region that fits into the support groove 41 and is supported. That is, in the bimorph vibrator 13, a pair of peripheral parts 19 facing each other in the longitudinal direction with the center of gravity G interposed therebetween are located within the region of the support groove 41 as the support peripheral part 43. In addition, the area around the other group facing each other across the center of gravity G is the free area 42.
It is located outside the area of the support groove 41.

According to the above support structure, the bimorph resonator 1
3, only the edges of a pair of peripheral parts 19 facing each other across the center of gravity G in the longitudinal direction are located within the area of the support groove 41 as the supporting peripheral part 43, and another set of peripheral parts facing each other with the center of gravity G in between is located outside the area of the support 27 as a free periphery 42 . Therefore, the displacement of the bimorph oscillator 13 can be made larger than that of the first embodiment in which the entire periphery of the bimorph oscillator 13 is restrained by the pump body 2. Therefore, the discharge amount of the piezoelectric pump 1 becomes larger, and the efficiency can be improved.

Note that the other structures and operations are the same as those of the above embodiments except for those described below.

Note that the present invention is not limited to the above embodiments. For example, a piezoelectric actuator may be constructed using a monomorph vibrator instead of a bimorph vibrator.

[Purpose of the Invention] As explained above, according to the present invention, the electrode of the piezoelectric diaphragm of a piezoelectric pump is divided into a central part side and a peripheral part side supported by the pump body, and Since the drive is performed by applying AC voltages with opposite polarities to each electrode on the peripheral side, when driving the piezoelectric diaphragm by applying AC voltages with different polarities to each electrode, In this restraint support, the amount of displacement of the piezoelectric diaphragm can be increased, and the discharge flow rate by the piezoelectric diaphragm increases per cycle of the applied AC voltage. In other words, the amount of displacement of the piezoelectric diaphragm relative to the size of the piezoelectric diaphragm becomes large, a sufficient discharge amount can be obtained, and the efficiency of the piezoelectric pump can be improved.

[Brief explanation of drawings]

1 to 6 show a first embodiment of the present invention, in which FIG. 1 is a side sectional view of a piezoelectric pump, FIG. 2 is an exploded perspective view of its piezoelectric actuator, and FIGS. 3 and 4 are FIG. 5(a) is a configuration diagram showing the drive system of the piezoelectric actuator, and FIG. 5(b) is a side sectional view showing the curved state of the piezoelectric actuator.
) is an explanatory diagram of the drive signal applied to the piezoelectric actuator at that time, FIG. 6(a) is a side sectional view showing another curved state of the piezoelectric actuator, and FIG. 6(b) is an explanatory diagram of the drive signal applied to the piezoelectric actuator at that time. FIG. 3 is an explanatory diagram of a drive signal to be applied. FIG. 7 is a configuration diagram showing a drive system for a piezoelectric actuator according to a second embodiment of the present invention. 8 to 13 show a third embodiment of the present invention,
Fig. 8 is a perspective view of the piezoelectric diaphragm in the piezoelectric actuator, Fig. 9 is a side sectional view of the piezoelectric pump, Fig. 10 is an enlarged sectional view of the support part of the piezoelectric diaphragm, and Fig. 11 is a front sectional view of the piezoelectric pump. FIG. 12 is an enlarged sectional view of the support portion of the piezoelectric diaphragm, and FIG. 13 is a partially sectional plan view of the piezoelectric actuator. 1...Piezoelectric pump, 2...Pump body, 3...
Piezoelectric actuator, 5... Pump chamber, 6... Inlet, 7... Outlet, 13... Bimorph vibrator, 1
7... Peripheral electrode, 18... Central electrode, 1... Peripheral part, 20... Central part, 2 1 , 2 2... Control line, 2 3... Inverter, 2 3 ・- Power supply, 2 4...control unit, 3 3...inverter, 31, 32...control unit.

Claims (1)

[Claims] At least one inner surface of the pump chamber formed in the pump body is configured with a piezoelectric diaphragm, and by applying a voltage to the piezoelectric diaphragm, the piezoelectric diaphragm is displaced and the internal volume of the pump chamber is changed. In a piezoelectric pump that sucks and discharges fluid, the electrodes of the piezoelectric diaphragm are divided into a central part and a peripheral part supported by the pump body, and each electrode on the central part and peripheral part is divided into two parts. A piezoelectric pump characterized by comprising a driving means for applying an alternating current voltage having opposite polarities to the piezoelectric pump.