ACTUATOR AND FLUID CONTROL DEVICE

An actuator includes a first main plate at which a piezoelectric element is disposed, a frame body, and a connection part. The frame body is disposed on an outer side of an outer edge of the first main plate and apart from the first main plate. The connection part is disposed between the first main plate and the frame body. The connection part has a plurality connection bodies and a gap, which are disposed along the outer edge, the plurality of connection bodies being connected to the first main plate and the frame body, the gap being disposed between the plurality of connection bodies. The first main plate and the connection bodies are made of the same material. A thickness of the connection bodies is more than a thickness of the first main plate.

BACKGROUND OF THE DISCLOSURE

Field of the Disclosure

The present disclosure relates to an actuator including a plate that vibrates and a mechanism that supports the plate so that the plate can vibrate, and to a fluid control device including the actuator.

Description of the Related Art

Patent Document 1 describes a fluid control device including a diaphragm unit. The diaphragm unit in Patent Document 1 includes a diaphragm, a frame plate, and a connection part. The frame plate has a shape surrounding an outer edge of the diaphragm. The connection part connects the outer edge of the diaphragm and the frame plate to each other.

Here, the connection part has an easily deformable shape and elastically supports the diaphragm. Therefore, even if the frame plate is fixed, the diaphragm can perform a predetermined bending vibration.Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013-57247

BRIEF SUMMARY OF THE DISCLOSURE

However, since a connection part such as the connection part in Patent Document 1 has an easily deformable shape, the connection part tends to be damaged due to, for example, external shock. When, due to an operation of a pump, which is an example of a fluid control device, a pressure difference occurs between an upper surface and a lower surface of the actuator (an upper surface and a lower surface of the diaphragm) including the diaphragm and the connection part, the connection part is deformed, as a result of which a stress is produced in a drive body disposed on the diaphragm, and thus the drive body tends to be damaged.

Therefore, an object of the present disclosure is to provide an actuator that is not easily damaged while realizing a desired vibration.

An actuator of the disclosure includes a first main plate, a frame body, a connection part, and a drive body. The frame body is disposed on an outer side of an outer edge of the first main plate and apart from the first main plate. The connection part is disposed between the first main plate and the frame body. The drive body is disposed at the first main plate, and causes the first main plate to perform a bending vibration. The connection part has a connection body and a gap that are disposed along the outer edge, the connection body being connected to the first main plate and the frame body, the gap being adjacent to the connection body. The first main plate and the connection body are made of a same material. An average thickness of the connection body is more than an average thickness of the first main plate.

In this structure, since the connection body is thick, the structural durability of the connection body with respect to an external force is increased and thus the connection body is not easily damaged. Since a vibration that is a feature of the actuator is produced at the first main plate, a predetermined vibration can be obtained.

According to the disclosure, it is possible to realize an actuator that is not easily damaged while realizing a desired vibration.

DETAILED DESCRIPTION OF THE DISCLOSURE

First Embodiment

A fluid control device according to a first embodiment of the present disclosure is described with reference to the drawings.FIG. 1is an exploded perspective view of the fluid control device including an actuator according to the first embodiment.FIG. 2is a sectional view showing a structure of the fluid control device according to the first embodiment.FIG. 3is a plan view of a flat plate including a first main plate of the actuator according to the first embodiment. Note that, inFIG. 3, differences in thicknesses are denoted by differences in hatching.

In each figure showing a corresponding one of the embodiments below, for clarity, the shape of each structural element is partly or in its entirety illustrated in an exaggerated manner. For easily understanding the drawings, some reference signs of structural elements that can be univocally conjectured are omitted.

(Structure of Fluid Control Device10)

As shown inFIGS. 1 and 2, a fluid control device10includes a first main plate21, a frame body22, a connection part23, a piezoelectric element30, a second main plate40, and a connection member50. The piezoelectric element30corresponds to a “drive body” in the present disclosure. The first main plate21, the frame body22, the connection part23, and the piezoelectric element30constitute an actuator11.

As shown inFIGS. 1 and 3, the first main plate21is a flat plate having a circular shape in plan view. The first main plate21has a circular first main surface211and a circular second main surface212. The first main surface211and the second main surface212face each other. The first main plate21is made of, for example, a metal. The first main plate21is one that performs a bending vibration due to a distortion of the piezoelectric element30described below. “Bending vibration” is a vibration in which the first main surface211and the second main surface212are displaced in a wavelike manner in the side view of the first main plate21.

The frame body22is a flat plate, and the shape of the frame body22in plan view is such that an inner peripheral shape is a circular ring shape. The frame body22has a ring-shaped first main surface221and a ring-shaped second main surface222. The first main surface221and the second main surface222face each other. The frame body22is disposed on an outer side of an outer edge of the first main plate21. The frame body22is disposed away from the outer edge of the first main plate21, and, in plan view, surrounds the first main plate21. That is, the first main plate21is disposed in a space situated on an inner side of an inner peripheral end of the frame body22.

The connection part23is disposed between the first main plate21and the frame body22. The connection part23is disposed in a peripheral direction of the outer edge of the first main plate21. More specifically, the connection part23has a plurality of connection bodies231and a plurality of gaps232. The plurality of connection bodies231and the plurality of gaps232are alternately disposed adjacently to each other in the peripheral direction of the outer edge of the first main plate21. The plurality of connection bodies231are connected to the outer edge of the first main plate21and the inner peripheral end of the frame body22, and form a beam. The gaps232are arc-shaped grooves in plan view extending from the first main surface211of the first main plate21and the first main surface221of the frame body22to the second main surface212of the first main plate21and the second main surface222of the frame body22.

The first main plate21, the frame body22, and the plurality of connection bodies231are integrally formed from one plate. That is, the first main plate21, the frame body22, and the plurality of connection bodies231are formed by forming the plurality of gaps232in one plate and forming the external shape of the frame body22. Therefore, the first main plate21, the frame body22, and the plurality of connection bodies231are made of the same material. Note that the number of connection bodies231is not limited to three and may be four or more.

Due to such a structure, the first main plate21is held by the connection part23(more specifically, the plurality of connection bodies231) so that the first main plate21can vibrate with respect to the frame body22.

The piezoelectric element30includes a disc piezoelectric body and driving electrodes. The driving electrodes are formed on two main surfaces of the disc piezoelectric body.

The piezoelectric element30is disposed on the second main surface212of the first main plate21. Here, in plan view, the center of the piezoelectric element30and the center of the first main plate21substantially coincide with each other. The piezoelectric element30is distorted by applying a drive signal to the driving electrodes. The first main plate21performs a bending vibration due to this distortion.

Due to the structure above, the actuator11that realizes a predetermined function due to the bending of the first main plate21is provided.

The second main plate40is a circular flat plate in plan view. It is desirable that the second main plate40be made of a material with a thickness, etc. that hardly performs a bending vibration. The external shape of the second main plate40has a size that includes the external shape of a portion including the first main plate21, the connection part23, and the frame body22. The second main plate40has a circular main surface401and a circular main surface402. The main surface401and the main surface402face each other.

The second main plate40includes a through hole400. The main-surface-401side and the main-surface-402side of the second main plate40communicate with each other via the through hole400. The through hole400is disposed at a position overlapping the center of the second main plate40. Note that the position where the through hole400is disposed is not limited to the position overlapping the center of the second main plate40. For example, there may be a plurality of through holes400, and the plurality of through holes400may be disposed in the form of a ring around the center of the second main plate as an origin.

The second main plate40is disposed so that, with respect to the first main plate21, their main surfaces are in parallel. Here, the main surface401of the second main plate40and the first main surface211of the first main plate21face each other. The center of the second main plate40in plan view and the center of the first main plate21in plan view substantially coincide with each other.

The connection member50is a ring-shaped cylindrical body. It is desirable that the connection member50be made of a material with a thickness, etc. that hardly performs a bending vibration. The connection member50is disposed between the frame body22and the second main plate40. One end of the connection member50in a height direction is connected to the first main surface221of the frame body22. The other end of the connection member50in the height direction is connected to the main surface401of the second main plate40. Note that the connection member50may be formed separately from or integrally with the frame body22or the second main plate40.

Due to this structure, the fluid control device10includes a space surrounded by a flat plate, the second main plate40, and the connection member50, the flat plate including the first main plate21, the plurality of connection bodies231of the connection part23, and the frame body22. In this space, a space interposed between the first main plate21and the second main plate40is substantially a pump chamber100of the fluid control device10. The pump chamber100communicates with the through hole400and the plurality of gaps232of the connection part23. In other words, the pump chamber100communicates with the outside space of the fluid control device10via the through hole400and the plurality of gaps232of the connection part23.

In such a structure, due to a bending vibration of the first main plate21, a pressure distribution occurs inside the pump chamber100. Due to the bending vibration of the first main plate21, the pressure distribution inside the pump chamber100changes with time, and the fluid control device10can transport a fluid in a direction parallel to the first main surface211of the first main plate21. Therefore, for example, the fluid control device10can suck a fluid from the gaps232and discharge the fluid from the through hole400. Alternatively, the fluid control device10can transport a fluid in an opposite direction.

(More Specific Description of Supporting Structure of First Main Plate21)

As shown inFIG. 2, a thickness D23of the plurality of connection bodies231is more than a thickness D21of the first main plate21. Note that, in the present embodiment, since the thickness of the first main plate21is constant, the average thickness of the first main plate21is the same as the thickness D21.

Due to such a structure, the plurality of connection bodies231configured to hold the first main plate21so that the first main plate21can vibrate are thick and are not easily deformed. Therefore, the structural durability of the plurality of connection bodies231with respect to an external force is increased. That is, the plurality of connection bodies231are not easily broken or cracked by an external force. On the other hand, a vibration for realizing a desired function of the actuator11and the fluid control device10is realized by a bending vibration of the first main plate21. Therefore, due to this structure being realized, a bending vibration of the first main plate21required for the actuator11and the fluid control device10can be ensured.

Consequently, the actuator11and the fluid control device10of the present embodiment are not easily damaged while realizing a desired vibration, and the reliability of the actuator11and the fluid control device10of the present embodiment is enhanced. Further, when, due to an operation of a pump, which is an example of the fluid control device10, a pressure difference occurs between an upper surface and a lower surface of the actuator (the first main surface211and the second main surface212of the first main plate21) including the first main plate21and the plurality of connection bodies231, a stress toward the piezoelectric element30caused by deformation of the connection bodies231can be suppressed. Therefore, the damage to the piezoelectric element30can be suppressed. Consequently, the reliability of the fluid control device10is further enhanced.

The structure of the present embodiment has the following features. As shown inFIG. 2, a thickness D22of the frame body22is the same as the thickness D23of the plurality of connection bodies231. Therefore, any vibration that leaks to the frame body22is suppressed. Consequently, compared with when the frame body22is thin, the efficiencies of the actuator11and the fluid control device10are increased. Note that the thickness D22of the frame body22is to be more than or equal to the thickness D23of the plurality of connection bodies231, and, as the thickness D23increases, the leakage of the vibration can be suppressed. “Thickness” here refers to the average thickness, and as shown inFIG. 2, if the thickness is constant, the thickness is the same as the average thickness. This concept is also applied to other portions of the present application.

In the structure of the present embodiment, the first main surface211of the first main plate21, the first main surface221of the frame body22, and first main surfaces2311of the plurality of connection bodies231are flush with each other. On the other hand, the second main surface222of the frame body22and second main surfaces2312of the plurality of connection bodies231are flush with each other, and the second main surface212of the first main plate21is situated closer than the second main surface222of the frame body22and the second main surfaces2312of the plurality of connection bodies231to the first main surface211of the first main plate21.

In this structure, since at least a part of the piezoelectric element30is disposed inside a space formed by a step between the second main surfaces2312of the plurality of connection bodies231and the second main surface212of the first main plate21, the actuator11and the fluid control device10can be made thin.

(Derived Example of Supporting Mode of First Main Plate21)

FIGS. 4A, 4B, and 4Care each a sectional view showing a derived example of a supporting mode of the first main plate of the actuator according to the first embodiment.

In the mode inFIG. 4A, an actuator11A1is such that a second main surface212of a first main plate21, a second main surface222of a frame body22, and second main surfaces2312of a plurality of connection bodies231are flush with each other. In this structure, a first main surface211of the first main plate21is positioned closer than first main surfaces2311of the plurality of connection bodies231to the second main surface212of the first main plate21. Therefore, as long as the structure of the fluid control device described above is used, the volume of a pump chamber100can be increased.

In the mode inFIG. 4B, an actuator11A2is such that a first main plate21is connected to midway positions on a plurality of connection bodies231in a thickness direction thereof. In the mode inFIG. 4C, an actuator11A3is such that a first main plate21is connected to one connection body231so that a second main surface212is flush with a second main surface2312. In addition, the first main plate21is connected to the other connection body231so that a first main surface211is flush with a first main surface2311. Even with these structures, it is possible to realize such a structure that is not easily damaged while realizing the aforementioned desired vibration.

Second Embodiment

A fluid control device according to a second embodiment of the present disclosure is described with reference to the drawings.FIG. 5is a sectional view showing a structure of the fluid control device according to the second embodiment.

As shown inFIG. 5, a fluid control device10B according to the second embodiment differs from the fluid control device10according to the first embodiment in the structure of an actuator11B. The other structures of the fluid control device10B are the same as those of the fluid control device10, and the same portions are not described.

The actuator11B includes a first main plate21B. The first main plate21B has a first region201and a second region202. The first region201and the second region202are disposed in this order from the center to an outer edge of the first main plate21B. In other words, the first region201is a region that does not include the outer edge of the first main plate21B, and the second region202is a region that surrounds the first region201and that includes the outer edge of the first main plate21B.

A thickness D201of the first region201is more than a thickness D202of the second region202. Main surfaces, situated on a pump-chamber-100side, of the first region201and the second region202are connected so as to be flush with each other, and constitute a first main surface211. A second main surface2012of the first region201is disposed further away than a second main surface2022of the second region202from the first main surface211.

A piezoelectric element30is disposed on the second main surface2012of the first region201.

In such a structure, in order to obtain a predetermined resonance frequency, the first main plate21B can be made thin. Therefore, the vibration displacement of the first main plate21B can be increased. Consequently, for example, the drive voltage of the piezoelectric element30can be reduced, and the efficiencies of the actuator11B and the fluid control device10B can be increased.

Here, since the thickness D202of the second region202is less than the average thickness of the first main plate21B, the vibration displacement near the outer edge of the first main plate21B can be further increased. Therefore, the efficiencies of the actuator11B and the fluid control device10B can be further increased.

Since the first main surface211of the first main plate21B is flat from the center to the outer edge, that is, the entire surface on the pump-chamber-100side is a flat surface, the plane area of the pump chamber100that substantially affects the function of fluid control (fluid transport) of the fluid control device10can be increased, and the volume can be increased. Therefore, the efficiency of the fluid control device10B can be further increased.

In the structure of the actuator11B, an upper end surface (the first main surface211) of the first main plate21B in a thickness direction, upper end surfaces (first main surfaces2311) of connection bodies231in the thickness direction, and an upper end surface (a first main surface221) of a frame body22in the thickness direction are flush with each other. Further, a lower end surface (the second main surface2012of the first region201) of the first main plate21B in the thickness direction, lower end surfaces (second main surfaces2312) of the connection bodies231in the thickness direction, and a lower end surface (a second main surface222) of the frame body22in the thickness direction are flush with each other. Therefore, the thicknesses of the first main plate21B, the connection bodies231, and the frame body22can be stably provided and a structural body thereof can be formed. Consequently, variations in vibration characteristics of the actuator11B can be reduced.

Third Embodiment

A fluid control device according to a third embodiment of the present disclosure is described with reference to the drawings.FIG. 6is a sectional view showing a structure of the fluid control device according to the third embodiment.

As shown inFIG. 6, a fluid control device10C according to the third embodiment differs from the fluid control device10according to the first embodiment in the structure of an actuator11C. The other structures of the fluid control device10C are the same as those of the fluid control device10, and the same portions are not described.

The actuator11C includes a first main plate21C. The first main plate21C has a first region201and a second region202. The first region201and the second region202are disposed in this order from the center to an outer edge of the first main plate21C.

A thickness D201of the first region201is more than a thickness D202of the second region202. Main surfaces, situated on a side opposite to a pump-chamber-100side, of the first region201and the second region202are connected so as to be flush with each other, and constitute a second main surface212. A first main surface2011of the first region201is disposed further away than a first main surface2021of the second region202from the second main surface212.

A piezoelectric element30is disposed on the second main surface212, and, in plan view, partly overlaps the first region201.

In such a structure, as with the fluid control device10B according to the second embodiment, the vibration displacement of the first main plate21C can be increased. Therefore, the efficiencies of the actuator11C and the fluid control device10C can be increased.

Here, it is desirable that the thickness D202of the second region202be less than the average thickness of the first main plate21C. Due to such a structure, the vibration displacement near the outer edge of the first main plate21C can be further increased. Therefore, the efficiencies of the actuator11C and the fluid control device10C can be further increased.

In the structure of the actuator11C, an upper end surface (the first main surface2011of the first region201) of the first main plate21C in a thickness direction, upper end surfaces (first main surfaces2311) of connection bodies231in the thickness direction, and an upper end surface (a first main surface221) of a frame body22in the thickness direction are flush with each other. Further, a lower end surface (the second main surface212) of the first main plate21C in the thickness direction, lower end surfaces (second main surfaces2312) of the connection bodies231in the thickness direction, and a lower end surface (a second main surface222) of the frame body22in the thickness direction are flush with each other. Therefore, the thicknesses of the first main plate21C, the connection bodies231, and the frame body22can be stably provided and a structural body thereof can be formed. Consequently, variations in vibration characteristics of the actuator11C can be reduced.

Fourth Embodiment

A fluid control device according to a fourth embodiment of the present disclosure is described with reference to the drawings.FIG. 7is a sectional view showing a structure of the fluid control device according to the fourth embodiment.

As shown inFIG. 7, a fluid control device10D according to the fourth embodiment differs from the fluid control device10B according to the second embodiment in the structure of an actuator11D. The other structures of the fluid control device10D are the same as those of the fluid control device10B, and the same portions are not described.

The actuator11D differs from the actuator11B according to the second embodiment in that the actuator11D includes a first main plate21D. The other structures of the actuator11D are the same as those of the actuator11B, and the same portions are not described.

The first main plate21D differs from the first main plate21B according to the second embodiment in that the first main plate21D has a recessed portion213. The other structures of the first main plate21D are the same as those of the first main plate21B, and the same portions are not described.

The recessed portion213has a cylindrical shape including the center of a first region201, that is, the center of the first main plate21D. The recessed portion213has a shape that is recessed from a first main surface211in the first region201. Here, it is desirable that the shape of the recessed portion213be set in a range in which a thickness D202of a second region202is less than the average thickness of the first region201.

Even with such a structure, the actuator11D and the fluid control device10D provide the same operational effects as those of the actuator11B and the fluid control device10B described above. Further, due to such a structure, the fluid control device10D can suppress the contact of a central portion of the first main plate21D with a second main plate40caused by a bending vibration of the first main plate21D.

Fifth Embodiment

A fluid control device according to a fifth embodiment of the present disclosure is described with reference to the drawings.FIG. 8is a sectional view showing a structure of the fluid control device according to the fifth embodiment.

As shown inFIG. 8, a fluid control device10E according to the fifth embodiment differs from the fluid control device10according to the first embodiment in the structure of a connection member50E. The other structures of the fluid control device10E are the same as those of the fluid control device10, and the same portions are not described.

The connection member50E includes a plurality of beads51and an adhesive52. The plurality of beads51have a predetermined particle diameter. Note that the particle diameter of the plurality of beads51need not be constant, and may be set as appropriate in accordance with the height of a pump chamber100.

The connection member50E is configured to adhere a main surface401of a second main plate40and a first main surface221of a frame body22to each other by the adhesive52. Here, the particle diameter of the plurality of beads51mixed with the adhesive52provides the distance between the main surface401of the second main plate40and the first main surface221of the frame body22, that is, the height of the pump chamber100.

Even with such a structure, the fluid control device10E can provide the same operational effects as those of the fluid control device10.

Note that, in the description above, the connection part23includes a plurality of connection bodies231and a plurality of gaps232that are alternately disposed adjacently to each other in a peripheral direction. However, the connection part23may include gaps that are adjacent to a connection body in a radial direction (a direction orthogonal to a peripheral direction and a thickness direction).FIG. 9is a plan view showing another example of a flat plate including a first main plate of an actuator.

As shown inFIG. 9, a connection part has a ring-shaped connection body231and a plurality of gaps232. The ring-shaped connection body231has a continuous shape in a full circumference along an outer edge of a first main plate21. The plurality of gaps232have an arc shape, and are disposed adjacently to the ring-shaped connection body231in the radial direction orthogonal to the peripheral direction. In other words, the plurality of gaps232are disposed between the ring-shaped connection body231and the first main plate21and between the ring-shaped connection body231and a frame body22.

The plurality of gaps232are disposed apart from each other in the peripheral direction. At portions between the plurality of gaps232, the ring-shaped connection body231is connected to the first main plate21and the frame body22. Even the portions between the plurality of gaps232can be included in a part of the connection body of the present application.

Even with such a structure, by applying the relationship between the thicknesses described above, the operational effects described above can be realized.

In each of the embodiments described above, although the shape of the first main plate in plan view is a circular shape, even if the shape is a regular polygonal shape, in particular, a regular polygonal shape having many angles, the structures described above can be applied. However, when the first main plate has a circular shape, vibration is produced uniformly around the entire circumference, and thus the vibration efficiency is increased, which is more desirable. Here, it is desirable that an inner edge of the frame body have a circular shape along the outer edge of the first main plate. Due to the inner edge of the frame body having a circular shape, the circular first main plate is easily supported in a balanced manner. In each of the embodiments described above, although an outer edge of the frame body22has a circular shape, the external shape of the frame body22is not limited to a circular shape and can be set as appropriate.

Although each part described above has a constant thickness, each part described above may partly differ in thickness as long as the difference is within a predetermined range (for example, within a manufacturing error range, an allowable range in terms of performance). In this case, the thickness of each part mentioned above may be considered as the average thickness.

In each of the embodiments described above, the first main plate, the frame body, and the plurality of connection bodies are integrally formed with each other. However, the first main plate and the plurality of connection bodies may be integrally formed with each other, and the frame body may be formed separately from the first main plate and the plurality of connection bodies. Alternatively, the first main plate, the plurality of connection bodies, and the frame body can be formed separately from each other. In this case, a structure that increases the structural durability of the plurality of connection bodies with respect to an external force, for example, a material having a high rigidity is to be used. However, by using the structure according to any one of the embodiments mentioned above, while easily forming the actuator and the fluid control device, the operational effects described above can be realized, which is practically more effective.

The structures of the respective embodiments described above can be combined as appropriate, and operational effects corresponding to each of the combinations can be realized.10,10B,10C,10D,10E fluid control device11,11A1,11A2,11A3,11B,11C,11D actuator21,21B,21C,21D first main plate22frame body23connection part30piezoelectric element40second main plate50,50E connection member51bead52adhesive100pump chamber201first region202second region211first main surface of first main plate21212second main surface of first main plate21213recessed portion221first main surface of frame body22222second main surface of frame body22231connection body232gap400through hole401main surface of second main plate40402main surface of second main plate402011first main surface of first region2012012second main surface of first region2012021first main surface of second region2022022second main surface of second region2022311first main surface of connection body2312312second main surface of connection body231