ACTUATOR AND FLUID CONTROL DEVICE

Abstract

An actuator (11) comprises a main plate (21), a frame (22), a connecting member (23), and a piezoelectric element (30). The main plate (21) has a main surface (201) and a main surface (202) and has a rotationally symmetrical shape in plan view. The frame (22) is disposed outside an outer peripheral edge (e21) of the main plate (21). The connecting member (23) connects the outer peripheral edge (e21) of the main plate (21) and the frame (22), and holds the main plate (21) such that the main plate (21) can vibrate in relation to the frame (22). A piezoelectric element (30) is disposed on the main surface (201) of the main plate (21), and the outer shape is smaller than the main plate (21). The main plate (21) is provided with a recess (210) and a thin portion (219) in an area that in plan view does not include a center (o21) and the outer peripheral edge (e21) of the main plate (21), and as a result, a low-elastic-modulus area is formed which has a lower elastic modulus than that of the portion of the center (o21).

Description

[Technical field]

[0001] The present invention relates to an actuator having a structure in which a flat plate is vibrated by a driver such as a piezoelectric element 30 . [Background technology]

[0002] Patent Document 1 discloses a piezoelectric pump equipped with an actuator. The actuator in Patent Document 1 is configured by attaching a piezoelectric element to a circular vibration plate.

[0003] An outer frame is disposed outside the diaphragm. The diaphragm is connected to the outer frame by a beam-shaped connecting member. This allows the diaphragm to be held in a vibrating manner relative to the outer frame.

[0004] When the actuator is viewed in a plan view (viewed in a direction perpendicular to the main surface of the diaphragm when the amplitude is 0), the center of the piezoelectric element coincides with the center of the diaphragm.

[0005] The piezoelectric element is composed of a piezoelectric body and a driving conductor disposed on a main surface of the piezoelectric body. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5177331 Summary of the Invention [Problem to be solved by the invention]

[0007] Since piezoelectric bodies are brittle materials, cracks CR tend to occur when the tensile stress becomes greater than the compressive stress. If multiple cracks occur and connect to each other, the area surrounded by these multiple cracks CR becomes an area of ​​the piezoelectric element that is insulated from other parts.

[0008] A driving voltage is not applied to this insulated region, and the distortion generated by the piezoelectric element is small, which reduces the amplitude of the actuator vibration and degrades the actuator characteristics.

[0009] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an actuator capable of suppressing a decrease in the amplitude of vibration even if a crack occurs in a piezoelectric element. [Means for solving the problem]

[0010] The actuator of the present invention includes a main plate, a frame, a connecting member, and a piezoelectric element. The main plate has a first main surface and a second main surface, and has a rotationally symmetric shape in a plan view seen from a direction perpendicular to the first main surface and the second main surface. The frame is disposed outward from the outer periphery of the main plate. The connecting member connects the outer periphery of the main plate and the frame, and holds the main plate vibratably relative to the frame. The piezoelectric element is disposed on the first main surface of the main plate, and has an outer shape smaller than that of the main plate. In a plan view, the main plate does not include the center and the outer periphery of the main plate, and has a low deformation region in an area overlapping the piezoelectric element, the low deformation region having a lower elastic modulus than the central portion.

[0011] In this configuration, the amplitude of the main plate is large in the deformation control region, and a large tensile stress acts on the main plate. Furthermore, by arranging the deformation control region at a position away from the center of the main plate and the piezoelectric element, even if a crack occurs, the occurrence of an area surrounded by multiple cracks is suppressed. This suppresses the occurrence of an area in the piezoelectric element where the drive voltage is not applied. Effect of the Invention

[0012] According to this invention, even if a crack occurs in the piezoelectric element, the decrease in the amplitude of vibration of the actuator can be suppressed. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is an exploded perspective view of a fluid control device including an actuator according to a first embodiment. [Diagram 2]FIG. 2A is a plan view of the actuator according to the first embodiment, and FIG. 2B is a cross-sectional view taken along line AA of FIG. [Diagram 3] FIG. 3 is a graph showing an example of the distribution of tensile stress. [Figure 4] FIG. 4(A) is a diagram showing an example of how cracks CR occur in the configuration of the first embodiment, and FIG. 4(B) is a diagram showing an example of how cracks CR occur in a conventional configuration. [Diagram 5] FIG. 5 is a graph showing the relationship between the position of the thin portion 219 and the normalized life. [Figure 6] FIG. 6(A) is a plan view of the actuator according to the second embodiment, and FIG. 6(B) is a BB cross-sectional view thereof. [Figure 7] FIG. 7 is a plan view of the actuator according to the third embodiment. [Figure 8] FIG. 8(A) is a plan view of an actuator according to a fourth embodiment, and FIG. 8(B) is a cross-sectional view taken along line CC thereof. [Figure 9] FIG. 9(A) is a plan view of an actuator according to a fifth embodiment, and FIG. 9(B) is a DD cross-sectional view thereof. [Figure 10] FIG. 10A is a plan view of an actuator according to a sixth embodiment, and FIG. 10B is an E-E cross-sectional view thereof. [Figure 11] FIG. 11 is a side cross-sectional view of the actuator according to the seventh embodiment. [Figure 12] FIG. 12A is a plan view of an actuator according to an eighth embodiment, and FIG. 12B is an FF cross-sectional view thereof. [Figure 13] FIG. 13 is a side cross-sectional view of the actuator according to the ninth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] [First embodiment] An actuator and a fluid control device according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of a fluid control device including an actuator according to the first embodiment. FIG. 2(A) is a plan view of the actuator according to the first embodiment, and FIG. 2(B) is a cross-sectional view taken along line AA thereof. In each embodiment including this embodiment, the shapes of the respective components are partially or entirely exaggerated in each drawing to make the configuration of the actuator and the fluid control device easier to understand.

[0015] (Configuration of actuator 11) As shown in FIG. 1, FIG. 2(A) and FIG. 2(B), the actuator 11 includes a flat plate member 20 and a piezoelectric element 30. The flat plate member 20 and the piezoelectric element 30 are arranged in a plane parallel to the plane of the piezoelectric element 30. As shown in FIG.

[0016] (Configuration of the flat plate member 20) The flat plate member 20 is made of a metal plate or the like, and has a main surface 201 and a main surface 202. The flat plate member 20 includes a main plate 21, a frame body 22, and a plurality of connecting members 23. The main plate 21, the frame body 22, and the plurality of connecting members 23 are integrally formed using, for example, a single flat plate.

[0017] The main plate 21 is a flat plate having a main surface 201 and a main surface 202. The main surface 201 corresponds to the "first main surface" of the present invention, and the main surface 202 corresponds to the "second main surface" of the present invention.

[0018] The shape of the main plate 21 in a plan view (the shape when viewed in a direction (thickness direction) perpendicular to the main surfaces 201 and 202) is circular. The main plate 21 has a center o21 and an outer peripheral edge e21. Note that the main plate 21 is not limited to being circular, and as long as it has a rotationally symmetric shape with the center o21 as the reference point, the configuration of the present application can be applied and the effects of the present application can be achieved.

[0019] Furthermore, the main plate 21 is formed with a thin portion 219. The specific shape and the position where the thin portion 219 is formed will be described later.

[0020] The frame body 22 is a flat plate, and the outer shape of the frame body 22 in plan view is a square. However, the outer shape of the frame body 22 in plan view does not have to be limited to a square. An opening is formed in the frame body 22. The opening penetrates the flat plate constituting the frame body 22 in the thickness direction. The opening is circular in plan view. The shape of the opening is larger than the outer peripheral edge e21 of the main plate 21 and is similar to the outer peripheral edge e21.

[0021] The main plate 21 is disposed inside the opening of the frame body 22. In this case, the center of the opening coincides with the center o21 of the main plate 21. Since the shape of the outer peripheral edge e21 of the main plate 21 is smaller than the shape of the opening of the frame body 22, even when the main plate 21 is disposed inside the opening of the frame body 22, the outer peripheral edge e21 of the main plate 21 and the frame body 22 are disposed at a distance from each other.

[0022] Each of the multiple connecting members 23 has a beam shape. The multiple connecting members 23 are disposed in an opening between the main plate 21 and the frame body 22. The multiple connecting members 23 are disposed along the outer peripheral edge e21 of the main plate 21 at intervals from one another.

[0023] The connecting member 23 includes an inner connecting portion, a beam portion, and an outer connecting portion. The beam portion extends along the outer peripheral edge e21 of the main plate 21. The inner connecting portion connects approximately the center of the beam portion in the extending direction to the outer peripheral edge e21 of the main plate 21. The outer connecting portion connects both ends of the beam portion in the extending direction to the frame body 22.

[0024] With this configuration, the main plate 21 is supported by the multiple connecting members 23 in a state in which it can vibrate in a bending manner relative to the frame body 22 .

[0025] The piezoelectric element 30 has a circular shape in a plan view. The outer shape of the piezoelectric element 30 is smaller than the outer shape of the main plate 21 (the shape of the outer peripheral edge e21). The piezoelectric element 30 includes a piezoelectric body and a driving conductor. The driving conductor is formed on the main surface of the piezoelectric element 30.

[0026] The piezoelectric element 30 is disposed on the main surface 201 of the main plate 21. In this case, the center of the piezoelectric element 30 coincides with the center of the main plate 21. Note that the term "coincidence" here also includes a range in which the respective center positions are misaligned within the range of manufacturing error.

[0027] Since the outer shape of the piezoelectric element 30 is smaller than the outer shape of the main plate 21, the main plate 21 has an area that does not come into contact with the piezoelectric element 30 at the outer circumferential edge e21 and its vicinity.

[0028] In such a configuration, the thin portion 219 is realized by a recess 210 formed in the main plate 21. As shown in FIG. 1, FIG. 2(A), and FIG. 2(B), the recess 210 is a shape in which a part of the main plate 21 is recessed from the main surface 202 side. More specifically, the recess 210 is annular along the outer peripheral edge e21 of the main plate 21, with the center o21 of the main plate 21 as a reference point (center point (center of rotation)). The depth of the recess 210 is smaller than the thickness of the main plate 21. The recess 210 is formed at a position overlapping the piezoelectric element 30 in a plan view. The width of the recess 210 is, for example, approximately 1 / 4 of the radius of the main plate 21 (the distance from the center o21 to the outer peripheral edge e21). It is sufficient that the width is smaller than the radius.

[0029] As a result, the main plate 21 has an annular thin portion 219 formed at a position that does not include the center o21 and the outer circumferential edge e21 and that overlaps with the piezoelectric element 30 in a plan view.

[0030] Here, main plate 21 is formed from one material. Therefore, thin portion 219 is more easily deformed than portions of main plate 21 other than thin portion 219. In other words, thin portion 219 has a lower elastic modulus than other portions of main plate 21. That is, thin portion 219 corresponds to the "low elastic modulus region" of the present invention.

[0031] In such a configuration, tensile stress is generated in the main plate 21 as shown below. Fig. 3 is a graph showing an example of the distribution of tensile stress. The horizontal axis of Fig. 3 is the normalized distance from the center o21, and the vertical axis of Fig. 3 is the tensile stress applied to the piezoelectric element 30 when the main plate 21 is subjected to bending vibration. The normalized distance from the center o21 is the distance from the center o21 when the center o21 is set as the origin and the distance from the center o21 to the outer circumferential edge e21 is set as 1. Fig. 3 also shows a case where the thin portion 219 is formed at a position from about 0.6 to about 0.8 of the normalized distance.

[0032] By forming the thin portion 219 at a position away from the center o21, the position where the amplitude in the main plate 21 is maximum is not the center o21 but the region where the thin portion 219 is formed. Therefore, as shown in Fig. 3, the tensile stress applied to the piezoelectric element 30 is the region facing the thin portion 219. In other words, the region where the tensile stress applied to the piezoelectric element 30 is maximum is the region facing the thin portion 219, not the region facing the center o21.

[0033] On the other hand, although not shown in the drawing, in a conventional configuration in which the thin portion 219 is not formed, the amplitude is largest at the center o21 of the main plate 21. For this reason, in the conventional configuration, the tensile stress is largest in the region facing the center o21.

[0034] However, by providing the thin portion 219, the region where the tensile stress is greatest changes from the center o21 to the thin portion 219, and the tensile stress at the center o21 becomes smaller than that in the conventional configuration.

[0035] For this reason, the shape of the cracks CR that occur in the piezoelectric element 30 due to the tensile stress changes as shown in Figures 4(A) and 4(B). Figure 4(A) is a diagram showing an example of the state of occurrence of the cracks CR in the configuration of the first embodiment, and Figure 4(B) is a diagram showing an example of the state of occurrence of the cracks CR in the conventional configuration.

[0036] First, as shown in Fig. 4(B), in the conventional configuration, the tensile stress is greatest at the center o21, so the cracks CR are concentrated around the center o21. Therefore, the cracks CR are likely to join together, and when the cracks CR join together, an insulating region surrounded by the cracks CR is likely to occur. When an insulating region occurs, the amplitude of vibration of the actuator 11 decreases, and the characteristics deteriorate.

[0037] On the other hand, as shown in Fig. 4(A) in the configuration of this embodiment, the tensile stress is greatest in the thin portion 219 close to the outer peripheral edge e21, so that the cracks CR occur at positions overlapping the thin portion 219 and at a distance from each other. Therefore, the cracks CR are hardly connected to each other. As a result, an insulating region surrounded by the cracks CR is unlikely to occur. By suppressing the occurrence of the insulating region, the decrease in the vibration amplitude of the actuator 11 is suppressed, and the deterioration of the characteristics is suppressed.

[0038] In this way, by using the configuration of this embodiment, the cracks CR generated in the piezoelectric element 30 can be made discrete, and the generation of insulating regions surrounded by the cracks CR can be suppressed. This allows the actuator 11 to suppress a decrease in the amplitude of vibration and suppress deterioration of the characteristics.

[0039] The position of the thin portion 219 in the direction from the center o21 to the outer peripheral edge e21 of the main plate 21 may be such that it does not include at least the center o21 or the outer peripheral edge e21 and overlaps with the piezoelectric element 30. However, by positioning the thin portion 219 at the following position, the reliability of the actuator 11 can be further improved.

[0040] Fig. 5 is a graph showing the relationship between the position of the thin portion 219 and the normalized lifespan. The horizontal axis of Fig. 5 shows the normalized distance from the center o21, which indicates the distance from the center o21 to the center of the thin portion 219 in the width direction. The width of the thin portion 219 is, for example, approximately 1 / 4 of the radius of the main plate 21. The vertical axis of Fig. 5 shows the time it takes for the actuator 11 to deteriorate to a predetermined characteristic when it is continuously driven, and is a value obtained by setting the case where the thin portion 219 does not exist as a reference value of "1".

[0041] 5, if the distance from the center o21 to the thin portion 219 is about 0.4 to about 0.9 times the distance to the outer peripheral edge e21, the life of the actuator 11 can be extended to about twice that of the conventional configuration. Furthermore, if the distance from the center o21 to the thin portion 219 is about 0.55 to about 0.85 times the distance to the outer peripheral edge e21, the life of the actuator 11 can be extended to about three times that of the conventional configuration. Furthermore, by making the distance from the center o21 to the thin portion 219 about 0.8 times the distance to the outer peripheral edge e21, the life of the actuator 11 can be extended to about four times that of the conventional configuration.

[0042] Furthermore, in the actuator 11, the recess 210 is formed on the surface of the main plate 21 opposite to the surface on which the piezoelectric element 30 is arranged. This causes the entire surface of the piezoelectric element 30 to abut against the main plate 21. In other words, the piezoelectric element 30 has no portion that is not in contact with the main plate 21. This further suppresses the occurrence of cracks CR in the piezoelectric element 30 due to tensile stress.

[0043] Furthermore, in the actuator 11, the recesses 210 and the thin portions 219 are uniformly arranged around the circumferential direction of the main plate 21. This allows the actuator 11 to suppress variation in vibration in all directions from the center o21 to the outer circumferential edge e21, improving the vibration characteristics of the actuator 11.

[0044] The width of the recess 210 does not have to be uniform around the entire circumference. The recess 210 may have a wide portion and a narrow portion, and as an example, may have a shape in which the wide portion and the narrow portion are repeated.

[0045] Furthermore, the depth of the recess 210 does not have to be uniform around the entire circumference. The recess 210 may have deep and shallow portions, and as an example, may have a shape in which the deep and shallow portions are alternately repeated.

[0046] Furthermore, the depth of the recess 210 does not have to be uniform in the width direction. For example, the recess 210 may be deeper in the center in the width direction than at the ends in the width direction.

[0047] (Configuration of the fluid control device 10) By using the actuator 11 having the above-mentioned configuration, a fluid control device 10 can be configured as shown in Fig. 1. The fluid control device 10 includes the actuator 11, a flat plate 40, and a sidewall member 50.

[0048] The flat plate 40 is disposed on the main surface 202 side of the main plate 21, the frame body 22, and the connecting member 23 of the actuator 11. The flat plate 40 faces the main surface 202 of the main plate 21. The flat plate 40 corresponds to the "opposing plate" of the present invention. The flat plate 40 has a plurality of through holes 400. The plurality of through holes 400 are disposed at positions overlapping the main plate 21 in a plan view.

[0049] The side wall member 50 is annular and has a hollow 500, and is disposed between the flat plate member 20 and the flat plate 40 of the actuator 11. The hollow 500 is Side wall member 50 The side wall member 50 is connected to the frame body 22 and the flat plate 40. The side wall member 50 has substantially the same shape as the opening formed by the inner circumferential end of the frame body 22 and the flat plate 40.

[0050] As a result, the space surrounded by the actuator 11, the sidewall member 50, and the flat plate 40 (the hollow 500 of the sidewall member 50) becomes a pump chamber. The pump chamber communicates with the external space on the flat plate 40 side of the fluid control device 10 via a plurality of through holes 400. The pump chamber also communicates with the external space on the actuator 11 side of the fluid control device 10 via a plurality of openings 241, 242 present between the plurality of connecting members 23.

[0051] In such a configuration, by vibrating the main plate 21 of the actuator 11, the fluid control device 10 draws in fluid from the multiple through-holes 400 and discharges the fluid from the openings 241, 242. Alternatively, the fluid control device 10 draws in fluid from the openings 241, 242 and discharges the fluid from the multiple through-holes 400.

[0052] The actuator 11 having the above-mentioned configuration enables the fluid control device 10 to suppress a decrease in the efficiency of transporting the fluid, and also enables the fluid control device 10 to have improved reliability.

[0053] Second Embodiment An actuator and a fluid control device according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 6(A) is a plan view of the actuator according to the second embodiment, and Fig. 6(B) is a BB cross-sectional view thereof.

[0054] 6(A) and 6(B), the actuator 11A according to the second embodiment differs from the actuator 11 according to the first embodiment in the configuration of a flat plate member 20A. Other configurations of the actuator 11A are similar to those of the actuator 11, and a description of similar parts will be omitted.

[0055] The flat plate member 20A includes a recess 211, a recess 212, and a recess 213 in the main plate 21. The recess 211, the recess 212, and the recess 213 are annular and have different radii. Specifically, the radius of the recess 212 is smaller than the radius of the recess 211, and the radius of the recess 213 is smaller than the radius of the recess 212.

[0056] The recesses 211, 212, and 213 are formed in this order in the direction from the center o21 toward the outer circumferential edge e21.

[0057] In such a configuration, the average thickness of the region from the recess 211 to the recess 213 in the direction from the center o21 to the outer peripheral edge e21 in the main plate 21 is smaller than the thickness of other parts in the main plate 21. That is, the region from the recess 211 to the recess 213 in the direction from the center o21 to the outer peripheral edge e21 in the main plate 21 becomes the thin portion 219A.

[0058] In this manner, with the configuration including the multiple recesses 211, 212, and 213, the actuator 11A, like the actuator 11, can suppress a decrease in the amplitude of vibration of the actuator 11A even if a crack CR occurs in the piezoelectric element 30.

[0059] Furthermore, in this configuration, even if the width of each of the plurality of recesses 211, 212, and 213 is reduced, a thin portion can be formed that provides the same effect as the above-mentioned recess 210. This makes it possible to apply a more uniform pressing force to the entire surface when mounting the piezoelectric element 30 on the main plate 21. This allows the piezoelectric element 30 to be mounted more reliably on the main plate 21, and the reliability of the actuator 11A can be further improved.

[0060] (Third embodiment) An actuator and a fluid control device according to a third embodiment of the present invention will be described with reference to the drawings. Fig. 7 is a plan view of the actuator according to the third embodiment.

[0061] 7, the actuator 11B according to the third embodiment differs from the actuator 11 according to the first embodiment in the configuration of a flat plate member 20B. Other configurations of the actuator 11B are similar to those of the actuator 11, and a description of similar parts will be omitted.

[0062] The flat plate member 20B differs from the flat plate member 20 in that the main plate 21 includes a recess 210B that is annular and has a regular octagonal shape in a plan view. In other words, the flat plate member 20B differs from the flat plate member 20 in that the main plate 21 includes a thin portion that is annular and has a regular octagonal shape in a plan view. The recess 210B and the thin portion thereby have a regular octagonal ring shape with the center o21 of the main plate 21 as the reference point (center point).

[0063] With this configuration, actuator 11B can suppress a decrease in the amplitude of vibration of actuator 11B, similar to actuator 11, even if a crack CR occurs in piezoelectric element 30. That is, even if the recess and thin portion are not limited to being circular, but are regular polygonal rings, a decrease in the amplitude of vibration of actuator 11B can be suppressed when a crack CR occurs in piezoelectric element 30.

[0064] (Fourth embodiment) An actuator and a fluid control device according to a fourth embodiment of the present invention will be described with reference to the drawings. Fig. 8(A) is a plan view of the actuator according to the fourth embodiment, and Fig. 8(B) is a cross-sectional view taken along CC thereof.

[0065] 8(A) and 8(B), the actuator 11C according to the fourth embodiment differs from the actuator 11 according to the first embodiment in the configuration of a flat plate member 20C. Other configurations of the actuator 11C are similar to those of the actuator 11, and a description of similar parts will be omitted.

[0066] The flat plate member 20C differs from the flat plate member 20 in that the main plate 21 is provided with a plurality of recesses 210C. The plurality of recesses 210C are circular in plan view. The plurality of recesses 210C are arranged at predetermined intervals on a circle with the center o21 of the main plate 21 as the reference point (center point). For example, in the case of Fig. 8(A) and Fig. 8(B), the flat plate member 20C of the actuator 11C has four recesses 210C arranged at rotationally symmetric positions with an angle difference of 90° from each other with the center o21 of the main plate 21 as the reference point (center point).

[0067] In this configuration, the main plate 21 has thin portions where the multiple recesses 210C are formed.

[0068] With this configuration, actuator 11C can suppress a decrease in the amplitude of vibration of actuator 11C, similar to actuator 11, even if a crack CR occurs in piezoelectric element 30. That is, even if the recess and thin portion do not have a continuous annular shape, when a crack CR occurs in piezoelectric element 30, a decrease in the amplitude of vibration of actuator 11C can be suppressed.

[0069] The number and arrangement of the recesses 210C are not limited to this example. In this case, the arrangement interval (angular interval) of the recesses 210C may be set according to the number of the recesses 210C. More specifically, the arrangement interval of the recesses 210C may be a value obtained by dividing 360° by the number of the recesses 210C. As a result, the recesses 210C are evenly arranged around the entire circumference, and the actuator 11C can suppress the variation in vibration in all directions from the center o21 to the outer circumferential edge e21, improving the vibration characteristics of the actuator 11C.

[0070] Furthermore, the shape of the recesses 210C in plan view is not limited to a circle, and may be, for example, a polygon or an arc along the outer periphery e21.

[0071] Fifth embodiment An actuator and a fluid control device according to a fifth embodiment of the present invention will be described with reference to the drawings. Fig. 9(A) is a plan view of the actuator according to the fifth embodiment, and Fig. 9(B) is a DD cross-sectional view thereof.

[0072] 9(A) and 9(B), the actuator 11D according to the fifth embodiment differs from the actuator 11C according to the fourth embodiment in the configuration of a flat plate member 20D. Other configurations of the actuator 11D are similar to those of the actuator 11C, and a description of similar parts will be omitted.

[0073] The flat plate member 20D has one recess 210D. In this configuration, the main plate 21 has a thin portion where one recess 210D is formed.

[0074] With this configuration, actuator 11D, like actuator 11C, can suppress a decrease in the amplitude of vibration of actuator 11D even if a crack CR occurs in piezoelectric element 30. That is, even if the recess and thin portion exist only in a specific direction from center o21, when a crack CR occurs in piezoelectric element 30, a decrease in the amplitude of vibration of actuator 11D can be suppressed.

[0075] Sixth embodiment An actuator and a fluid control device according to a sixth embodiment of the present invention will be described with reference to the drawings. Fig. 10(A) is a plan view of the actuator according to the sixth embodiment, and Fig. 10(B) is an E-E cross-sectional view thereof.

[0076] 10(A) and 10(B), the actuator 11E according to the sixth embodiment differs from the actuator 11C according to the fourth embodiment in the configuration of a flat plate member 20E. Other configurations of the actuator 11E are similar to those of the actuator 11C, and a description of similar parts will be omitted.

[0077] The flat plate member 20E differs from the flat plate member 20C in that the main plate 21 is provided with a plurality of through holes 210E. The through holes 210E are circular in plan view. The plurality of through holes 210E are arranged at predetermined intervals on a circle with the center o21 of the main plate 21 as the reference point (center point). For example, in the case of Fig. 10(A) and Fig. 10(B), the flat plate member 20E of the actuator 11E has four through holes 210E arranged at rotationally symmetric positions with an angle difference of 90° from each other with the center o21 of the main plate 21 as the reference point (center point).

[0078] In such a configuration, the portion where the multiple through holes 210E are formed in the direction from the center o21 toward the outer peripheral edge e21 is thinner on average than other portions in the direction from the center o21 toward the outer peripheral edge e21. This allows the main plate 21 to realize a thin portion in the portion where the multiple through holes 210E are formed in the direction from the center o21 toward the outer peripheral edge e21.

[0079] With this configuration, actuator 11E, like actuator 11C, can suppress a decrease in the amplitude of vibration of the actuator even if a crack CR occurs in piezoelectric element 30.

[0080] The number and arrangement of the through holes 210E are not limited to this example. In this case, the arrangement interval (angular interval) of the through holes 210E may be set according to the number of the through holes 210E. More specifically, the arrangement interval of the through holes 210E may be a value obtained by dividing 360° by the number of the through holes 210E. As a result, the through holes 210E are evenly arranged around the entire circumference, and the actuator 11E can suppress the variation in vibration in all directions from the center o21 to the outer circumferential edge e21, improving the vibration characteristics of the actuator 11E.

[0081] Seventh embodiment An actuator and a fluid control device according to a seventh embodiment of the present invention will now be described with reference to the drawings. Fig. 11 is a side cross-sectional view of the actuator according to the seventh embodiment.

[0082] 11, the actuator 11F according to the seventh embodiment differs from the actuator 11 according to the first embodiment in the configuration of a flat plate member 20F. Other configurations of the actuator 11F are similar to those of the actuator 11, and a description of similar parts will be omitted.

[0083] The actuator 11F includes a flat plate member 20F. The flat plate member 20F includes a main plate 21F, a frame body 22F, and a connecting member .

[0084] The main plate 21F includes a central portion 291 and an outer peripheral portion 292. The central portion 291 is thicker than the outer peripheral portion 292. The piezoelectric element 30 is disposed on a main surface 201 of the central portion 291. The recess 210 is formed in the main surface 202 of the central portion 291.

[0085] With this configuration, similar to actuator 11, even if a crack CR occurs in piezoelectric element 30, actuator 11F can suppress a decrease in the amplitude of vibration of actuator 11F.

[0086] Furthermore, in the actuator 11F, the outer peripheral edge portion 292 of the main plate 21F is thin, so that the amplitude of vibration near the outer peripheral edge e21 can be increased. Therefore, the actuator 11F can further suppress the decrease in the amplitude of vibration.

[0087] Eighth embodiment An actuator and a fluid control device according to an eighth embodiment of the present invention will be described with reference to the drawings. Fig. 12(A) is a plan view of the actuator according to the eighth embodiment, and Fig. 12(B) is an FF cross-sectional view thereof.

[0088] 12(A) and 12(B), an actuator 11G according to the eighth embodiment differs from the actuator 11 according to the first embodiment in the configuration of a flat plate member 20G. Other configurations of the actuator 11G are similar to those of the actuator 11, and a description of similar parts will be omitted.

[0089] The actuator 11G includes a flat plate member 20G. In the flat plate member 20G, a recess 210G is formed in the main surface 201 of the main plate . That is, a thin portion 219G is formed on the main surface 202 side of the main plate .

[0090] With this configuration, similar to the actuator 11, even if a crack CR occurs in the piezoelectric element 30, the actuator 11G can suppress a decrease in the amplitude of vibration of the actuator 11G.

[0091] Furthermore, when this configuration is applied to the configuration of the above-mentioned fluid control device 10, the pump chamber side surface of the main plate 21 can be made flat, thereby suppressing pressure loss for the fluid in the pump chamber.

[0092] Ninth embodiment An actuator and a fluid control device according to a ninth embodiment of the present invention will be described with reference to the drawings. Fig. 13 is a side cross-sectional view of the actuator according to the ninth embodiment.

[0093] 13, an actuator 11H according to the ninth embodiment differs from the actuator 11 according to the first embodiment in the configuration of a flat plate member 20H. Other configurations of the actuator 11H are similar to those of the actuator 11, and a description of similar parts will be omitted.

[0094] The actuator 11H includes a flat plate member 20H. In the flat plate member 20H, a recess 210H1 is formed in a main surface 201 of a main plate 21, and a recess 210H2 is formed in a main surface 202 of the main plate 21. That is, a thin portion 219H is formed in a middle position of the main plate 21 in the thickness direction.

[0095] With this configuration, similar to actuator 11, even if a crack CR occurs in piezoelectric element 30, actuator 11H can suppress a decrease in the amplitude of vibration of actuator 11H.

[0096] In the above description, the recess 210H1 and the recess 210H2 are entirely overlapped in plan view. However, the recess 210H1 and the recess 210H2 may be partially overlapped or may not be overlapped in plan view. The shapes of the recess 210H1 and the recess 210H2 may be the same or different. Furthermore, the recess 210H1 and the recess 210H2 may be a combination of an annular recess and a circular recess.

[0097] In this way, the actuator 11H can set the recesses 210H1 and 210H2 in a variety of ways, and therefore the shape of the thin portion 219H can be set in a variety of ways.

[0098] In the configurations of the above-mentioned embodiments, the thin portion is formed by forming a recess or a through hole in the main plate. However, as an actuator, if the elastic modulus is made lower in the region not including the center o21 than in the region not including the center o21, the above-mentioned effect can be realized. Therefore, the region where the elastic modulus is desired to be lower may be formed with a material having a lower elastic modulus than the other regions, or a cut may be formed.

[0099] Furthermore, the configurations of the above-described embodiments can be combined as appropriate, and effects according to each combination can be achieved. [Explanation of symbols]

[0100] 10: Fluid control device 11, 11A, 11B, 11C, 11D, 11E, 11F, 11G, 11H: Actuator 20, 20A, 20B, 20C, 20D, 20E, 20F, 20G, 20H: Flat plate members 21, 21F: Main board 22, 22F: Frame 23: Connecting member 30: Piezoelectric element 40: Flat plate 50: Side wall member 201: Main surface 202: Main surface 210, 210B, 210C, 210D: recess 210E:Through hole 210G, 210H1, 210H2, 211, 212, 213: recess 219, 219A, 219G, 219H: Thin part 241:Aperture 291: Central part 292: Outer edge 400:Through hole 500:Hollow

Claims

1. A main plate having a first main surface and a second main surface and having a rotationally symmetric shape when viewed in a plan view from a direction perpendicular to the first main surface and the second main surface; A frame body disposed outward from an outer peripheral edge of the main plate; a connecting member that connects an outer peripheral edge of the main plate to the frame and holds the main plate vibratably relative to the frame; a piezoelectric element disposed on the first main surface of the main plate, the piezoelectric element having an outer shape smaller than that of the main plate in the plan view and having a disk shape in the plan view; Equipped with The main plate is covering the piezoelectric element in the plan view, a low elastic modulus region having an elastic modulus smaller than that of the portion of the rotation center in a region that does not include the rotation center and the outer peripheral edge of the main plate and overlaps with the piezoelectric element in the plan view; An actuator, the low elastic modulus region is formed by a thin portion having a thickness smaller than that of the region of the rotation center in the main plate, the thin portion is formed by a recess recessed from the second main surface, The recess is annular with the rotation center as a reference point, The recess is formed in the second main surface. Actuator.

2. The recessed portion is formed at a plurality of positions from the rotation center toward the outer circumferential edge, The actuator of claim 1 .

3. An actuator according to claim 1 or 2; an opposing plate that faces the second main surface of the main plate, the connecting member, and the frame body and has a through hole in a portion overlapping the main plate; a sidewall member that is connected to the opposing plate and the frame and that forms a pump chamber together with the main plate, the connecting member, the frame, and the opposing plate; A fluid control device comprising:

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