JPH0242184A - Piezoelectric type micropump - Google Patents

Abstract

PURPOSE:To dispense with a mechanical check valve by providing piezoelectric members with independent piezoelectric plates on the feed port side and the discharge port side respectively on a plate-shaped member with a fluid path formed with the feed port and the discharge port at both ends to form one face of the fluid path. CONSTITUTION:A protruded section 19 to fix the center section of a piezoelectric member is formed at the center of a plate-shaped supporter frame 8 formed with a feed port 3 and a discharge port 4 at both ends, a linear fluid path 22 to communicate the feed port 3 and the discharge port 4 is formed. Electrodes 11a and 11b are stuck at both ends on a support plate 9 overlappingly stuck with the supporter frame 8, a piezoelectric plate 10 with conducting terminals 12a-12c are stuck at the center to constitute the piezoelectric member. A bellows type coupler 23 formed with multiple grooves on the front and rear faces of the support plate 9 is provided in the peripheral region of a piezoelectric plate 10 on the support plate 9, thereby the curved deformation of the piezoelectric member due to the excitation to the electrodes 11a and 11b is allowed, the pump function can be exerted.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a piezoelectric micropump.

[Conventional technology]

Generally, by pasting a piezoelectric material on one side of a metal plate and applying an electric field to the piezoelectric material, the piezoelectric material contracts in the plane direction due to the electric field applied in the polarization direction of the piezoelectric material. At this time, since this contraction is restrained by the bonding surface between the metal plate and the piezoelectric material, the entire structure can be deformed into a curved state.

If, for example, an AC voltage of an audio frequency is applied to this structure, the direction of curvature changes alternately, and by fixing a part of this structure, it becomes a sounding body.

As described above, if this structure is used, it is possible to use not only a sounding body but also a relay or an actuator that moves contacts, and various applied products related to these have been devised. For example, one of these applications is a piezoelectric micropump.

8th (a) to (c) are cross-sectional views for explaining a conventional piezoelectric micropump. As shown in FIG. 8(a), in this piezoelectric micropump, a piezoelectric bimorph diaphragm 2 is attached to a part of the outer wall of a plate member 1 in which a fluid path 6 is formed. A supply port 3 and a discharge port 4 are provided at both ends of the fluid path 6 . In addition, the supply port 3 and the discharge port 4 are provided with check valves 5b and 5, respectively.
A is attached.

Next, the operation of this piezoelectric micropump will be explained. The state shown in FIG. 8(a) is a stagnation state where fluid is filling the fluid path 6! It is. First, as shown in Figure 8(b),
When a voltage is applied to the diaphragm 2 through electrodes (not shown), the diaphragm 2 is bent and the fluid tends to flow in directions not shown by arrows 7a and 7c. At this time, the check valve 5b is closed by the pressure of the fluid trying to flow, the check valve 5a is opened by the pressure of the fluid trying to flow, and the fluid flows in the direction shown by the arrow 7b. Next, when the voltage applied to the diaphragm 2 is released, the diaphragm 2 is restored to its original state as shown in FIG. 1(c). The restoring force of the diaphragm 2 applies pressure to the fluid, the check valve 5b at the supply port 3 opens, and the other check valve 5a closes, filling the fluid path 6 with the fluid. This operation is repeated to supply fluid in one direction.

[Problem to be solved by the invention]

In the conventional piezoelectric micropump described above, a check valve is required at the supply port and the discharge port in order to flow fluid in the negative direction.9 This check valve is of a mechanical structure, so it can be miniaturized. There are limits to this. This is particularly difficult when the piezoelectric micropump is integrally made of ceramic.

An object of the present invention is to provide a piezoelectric microbob that does not require such a mechanical check valve.

[Means to solve the problem]

The piezoelectric micropump of the present invention includes a fluid path surrounded by inner surfaces of at least two plate-like members, at least one set of supply ports and discharge ports formed at both ends of the fluid path, and a fluid path that is connected to the fluid path. a piezoelectric member provided separately on the supply port side and the 4JF exit side of the at least one plate-shaped member formed, and a side of the piezoelectric member corresponding to the supply port side or the discharge port side; One side of the piezoelectric member on the opposite side is fixed to the plate member, and a bellows type joint is connected to the other three sides of the piezoelectric member to the plate member.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) and 1(b) are a perspective view and a sectional view of a piezoelectric micropump showing a first embodiment of the present invention.

As shown in FIG. 1, this piezoelectric micropump has a supply port 3 and a discharge port 4 at both ends of a support frame 8, which is a plate-like member.
are provided, and a straight fluid path 22 connecting these
is formed. A support plate 9, which is a plate-like member, is attached to cover the support 8, and the piezoelectric plate 10 of the support plate 9 has an electrode 11b and an electrode 11a on the supply port 3 side and the discharge port 4 side, respectively. It is provided. Further, terminals 12a, 12b, and 12c for applying voltage to these electrodes are formed between the electrode 11b and the electrode 11a. Furthermore, one side of the piezoelectric member consisting of an electrode, a piezoelectric plate, and a support plate below the piezoelectric member is connected to the support plate 9 where the terminal is located, and a plurality of grooves are formed on the front and back surfaces of the support plate 9 in the surrounding area of the other three sides. A bellows type joint 23 is provided.

FIG. 2 is an exploded perspective view of the piezoelectric micropump shown in FIG. 1. Next, the internal structure of this piezoelectric micropump will be explained. This piezoelectric micropump is disassembled into a support body 8, a support plate 9, and a piezoelectric plate 10.

A second groove 14 forming the supply port 3 and a groove 15 forming the discharge port 4 are formed in the support body 8, and a first groove 13 connecting these grooves and forming a fluid path is provided. ing. Furthermore, a protrusion 19 is provided between these two vortices to fix one side of the piezoelectric member.

The support plate 9 is provided with a support plate 9 around the area where the electrode 11a and the electrode 11b are attached, that is, one side of the electrode facing the supply port or the discharge port. Corners 16a and 16b from the front side and corners 17a and 17b from the back side are formed. By forming this plurality of groove structures, the piezoelectric member formed by the area of the adhesive surface 18 to which the piezoelectric plate 10 is bonded and the area of the support plate 9 around the piezoelectric member are connected to each other as shown in FIG. 1(b). This means that the bellows type joint 23 shown is formed.

A common electrode 20 is provided on the lower surface of the piezoelectric plate 10, and electrodes 11b and 11 are provided on the upper surface separately on the supply port side and the discharge side.
a is formed. Further, the common electrode 20 is connected to the terminal 12b.
, the electrode 11b is connected to the terminal 12c and the electrode 11a is connected to the terminal 1.
2a are connected to each other.

These structures are first adjusted by changing the outer shape of the piezoelectric plate 10 to the support plate 9.
The first boundary line 21a is aligned and adhered.

Next, the support plate 9 to which the piezoelectric plate 10 is bonded is connected to the side wall of the first groove 13 that becomes the fluid path 22 of the support body 8 and the second groove of the support plate 9.
and the boundary line 21b and adhere. This results in the piezoelectric micropump shown in FIG.

Next, a method of manufacturing this piezoelectric micropump will be explained. The substrate of the piezoelectric plate 10 is made of magnesium lead niobate (P
Powder of an electrostrictive material containing (Mgl8N28)03] as a main component is dispersed in a solvent together with an organic binder to form a slurry. A thick electric material green sheet having a uniform thickness of about 100 μm is produced using a slip casting method using a doctor blade. Next, this piezoelectric material green sheet is punched out to a specified size, and through holes are punched to connect the electrodes 11a and llb to the terminals 12a, 12b and 12c, respectively. Next, the electrodes 11a and llb are formed by printing a metal paste l- on the piezoelectric material Green Sea h by a screen printing method. Next, this piezoelectric material green sheet is fitted into a mold, and while heated at a temperature of around 100℃, it is heated to about 250℃.
A pressure of kg/cm2 is applied to make a piezoelectric green seal with increased density. Next, it is finished to predetermined dimensions using a press.

Next, in an oxidizing atmosphere, the temperature is slowly increased at a rate of 25°C/hour, maintained at about 500 to 600°C, organic matter in this sheet is removed, and further heated to 900 to 1200°C.
The piezoelectric plate 10 is completed by firing.

Next, the support plate 9 and the support body 8 are manufactured from stainless steel plates. In this support 8, grooves that will become the fluid passage 22, the supply port 3, and the discharge port 4 are formed, for example, to a depth of about 0.1 to 1 mm by a common chemical etching method. Further, the groove dimensions of the support body manufactured in this example are as follows: The groove width of the fluid path 22 is 20 mm, the depth Q is 2 nm, and the groove widths of the supply port 3 and the discharge port 4 are 5 mm. Depth 0.
It was 2 mm. Furthermore, the width of the groove connecting the grooves of the two fluid passages 22 was made to be 5 mm.

On the other hand, the support plate 9 is made of a stainless steel plate with a thickness of 0.05 to Q and about 1 mm. Once this plate thickness is set, the depth of the groove in the support 8 described above must be 315 mm or more of this plate thickness.

The piezoelectric plate 10 is adhered to the support plate 9 obtained in the above manner using an insulating epoxy adhesive or the like, and these piezoelectric bodies are further polarized with the electrode 11a, the common electrode 20, and the common electrode 11b. A DC power source is connected between each electrode 11b and an electric field of 1 kv/mm is applied for 1 minute.

3 and 4 are drive waveform diagrams and drive circuit diagrams applied to the piezoelectric plate, and FIGS. 5A to 5E are sectional views showing the order of operation of the piezoelectric micropump. First, Figure 5 (
In the state a>, no voltage is applied to either electrode, and the fluid in the fluid path 22 remains stagnant.

Next, in the state shown in FIG. 5(b), which is not shown in FIG. 4, the signal S1 enters the I transistor Tr1, and the transistor Tr
operates, and the voltage V as shown in FIG. 3 is generated as shown in FIG.
) is applied to the electrode 11b shown in FIG.

By applying this voltage, the piezoelectric plate 10 is bent and the fluid is pushed out in the direction of the arrow.

In the next C1 state shown in FIG. 5(c), the signal S2 enters the transistor Tr2 shown in FIG.
operates, and the voltage V shown in FIG. 3 is applied to the electrode 11a shown in FIG. 5(C). By applying this voltage, the piezoelectric plate 10
is deflected and the flow of fluid becomes unstoppable.

Next, in the state shown in FIG. 5(d), the signal SIA enters the transistor Tr3 shown in FIG. 4, the transistor Tr3 operates, and the voltage V shown in FIG. 3 is discharged through the resistor R7. The voltage applied to the electrode 11a shown in (d) is released. When this voltage is released, the piezoelectric plate 10 returns to its original state, and the fluid is sucked out from the supply port 3 by the restoring force of the piezoelectric board 1.0, as shown by the arrow.

Next, in the state shown in FIG. 5(e), the signal S2A enters the transistor Tr4 shown in FIG. 4, the transistor Tr4 operates, and the voltage ■ shown in FIG. 3 is discharged through the resistor R2. The voltage applied to the electrode 11a shown in (e) is released. When this voltage is released, the piezoelectric plate 10 is restored to its original state, and the fluid is sucked out from the supply port 3 by the restoring force of the piezoelectric board 10 and flows to the discharge port 4, as shown by the arrow.

Eventually, when the inertia of the fluid due to this restoring force is lost, the state returns to the state shown in FIG. 5(a).

Similarly, the pump operation can be performed by continuously repeating the operations shown in FIGS. 5(a) to 5(e). Note that with this operation, the supply port 3 f! Since the piezoelectric plates 10 on the IJ and discharge port 4 sides are operated independently at different times, this operation itself exhibits the effect of a check valve.

FIG. 6 is a sectional view of a piezoelectric micropump showing a second embodiment of the present invention. In this embodiment, the supporting plate 9a has 7s.
The second embodiment is the same as the first embodiment except that 25 is provided. By providing this 25 mm, the bonding area between the support plate 9a and the piezoelectric plate 10a becomes smaller compared to the first embodiment.
This support plate 9a has the advantage that it has increased flexibility and can operate at a lower voltage.

FIG. 7 is a perspective view of a piezoelectric micropump showing a third embodiment of the present invention. This embodiment has a supply port 3 and a discharge port 4.
and are in the same direction. Furthermore, piezoelectric plates 10b provided with electrodes 11a and llb are also formed side by side.

A partition portion 24 is provided between the fluid passages at the bottom of the piezoelectric plate 10b.
and are not connected by a fluid path 22b. The other structure and operation are the same as the first embodiment.

In the embodiments described above, a unimorph structure is used in which one piezoelectric plate is attached to the support plate, but a bimorph structure in which two piezoelectric plates are formed may be used. Note that in this case, there is an advantage that the operating voltage can be lowered. Furthermore, by covering the outer shell of this pump with an insulating resin, a piezoelectric micropump that can be thrown into a fluid tank can be obtained.

Furthermore, fluid channels can be provided on both sides of the support, and this mechanism can also be provided on both sides.

On the other hand, as an application example of this piezoelectric micropump, for example, if the discharge port is made into a nozzle shape and a pulse voltage is applied intermittently to the electrode, the appropriate fluid will be ejected from the nozzle and the Infusiera I. It can be used for etc.

〔Effect of the invention〕

As explained above, in the present invention, a piezoelectric member consisting of an independent piezoelectric plate and a supporting plate is formed on one side of the fluid path wall on the supply port side and the discharge port side, respectively. By applying voltage at different times and driving, the fluid can flow in one direction without flowing backwards. Therefore, it is possible to obtain a piezoelectric microbon 1 that does not require a mechanical check valve.

[Brief explanation of the drawing]

1(a) and (b) are a perspective view and a sectional view of a piezoelectric micropump showing a first embodiment of the present invention, FIG. 2 is an exploded perspective view of the piezoelectric micropump of FIG. 1, and FIG. Figures 3 and 4 are drive waveform diagrams and drive circuit diagrams applied to the piezoelectric plate, Figures 5 (a) to (e) are cross-sectional views showing the operating order of the piezoelectric micropump, and Figure 6 is a diagram of the drive waveform applied to the piezoelectric plate. A cross-sectional view of a piezoelectric micropump showing a second embodiment, and FIG. 7 is a cross-sectional view for explaining a wood-based micropump. 1... Plate member, 2... Vibration plate, 3... Supply port, 4
...4JF-outlet, 5a, 5b...return prevention valve, 6
．． 22...Fluid path, 7a, 7b, 7c-arrow, 8.
8a...Support body, 9.9a, 9b-...Support plate, 1
0.10 a-Piezoelectric plate, 11a, 1 lb...electrode, 12a, 12b, 12c...terminal, 13...first groove, 14...second groove, 15... Third groove, 1
6a, 16b--grooves on the front side, 17a, 17b...
Groove on back side, 18...Adhesive surface, 19...Protrusion, 20
...Common electrode, 21a...First boundary line, 21b.
...Second boundary line, 23...Bellows type joint, 24.
...Partition, 25...Groove.

Claims (1)

[Claims] a fluid path surrounded by inner surfaces of at least two plate-like members; at least one set of supply ports and outlet ports formed at both ends of the fluid path; and at least one of the plate-like members forming the fluid path. a piezoelectric member provided separately on the supply port side and the discharge port side; and one side of the piezoelectric member opposite to the side corresponding to the supply port side or the discharge port side of the piezoelectric member. A piezoelectric micropump comprising a bellows type joint fixed to the plate member and connecting the other three sides of the piezoelectric material to the plate member.