Pump structure

Abstract

To provide a technology that can improve properties of a pump for forcibly feeding a fluid by bend vibration of a plate-like piezoelectric actuator and miniaturize the pump.SOLUTION: A pump structure includes: an actuator capable of bend vibration; a stationary part provided so as to encapsulate the actuator; and a support part provided integrally with the stationary part and the actuator to be connected to the stationary part and the actuator and supporting the actuator so as to be capable of bend vibration with respect to the stationary part. The actuator and the stationary part respectively have non-similar shapes. When a virtual line is drawn so as to pass through a center point of the actuator on a plate surface, the support part is provided in a place where a difference between a distance from the center point to an outer shape of the stationary part intersecting the virtual line and a distance from the center point to an outer shape of the actuator intersecting the virtual line becomes the largest. The support part includes a folding back part capable of superposing the support part along the outer shape of the actuator.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pump structure. [Background technology]

[0002] Technologies related to pumps that pump fluid by bending vibration of a plate-shaped piezoelectric actuator have been developed (for example, Patent Documents 1 and 2). In the pump structure disclosed in Patent Documents 1 and 2, the bending vibration part of the piezoelectric actuator is supported by a surrounding fixed part. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2017 / 222122 [Patent Document 2] Patent No. 5177331 Summary of the Invention [Problem to be solved by the invention]

[0004] To improve the characteristics of pumps having the structures disclosed in Patent Documents 1 and 2, it is conceivable to increase the length of the support portion that supports the flexural vibration portion of the piezoelectric actuator relative to the fixed portion. The reason for this is that it is assumed that a decrease in the rigidity of the support portion would increase the amplitude of the piezoelectric actuator. However, in this case, the area occupied by the piezoelectric actuator and the support portion would increase, which would make it difficult to miniaturize the pump.

[0005] To achieve this, one approach to miniaturization would be to make the support section short and linear, increasing its rigidity so that it can support the piezoelectric actuator. However, this would reduce the amplitude of the piezoelectric actuator, potentially degrading the pump's performance. Therefore, one approach would be to thin the support section, but this could result in a support section with too little rigidity due to reduced processing precision. In other words, it is considered difficult for pumps with the structures disclosed in Patent Documents 1 and 2 to achieve both improved performance and miniaturization.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to provide a technology that makes it possible to achieve both improved characteristics of a pump that pumps a fluid by bending vibration of a plate-shaped piezoelectric actuator and a reduced size of the pump. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention employs the following configuration.

[0008] That is, a pump structure according to one aspect of the present invention comprises: a plate-shaped actuator whose plate surface can undergo flexural vibration due to the action of an element having a piezoelectric effect; a fixed portion arranged to surround the actuator in the direction of the plate surface at a predetermined distance from the outer shape of the actuator; and a support portion which is formed integrally with the fixed portion and the actuator, connecting the fixed portion and the actuator and supporting the actuator so as to allow the flexural vibration relative to the fixed portion, wherein the actuator and the fixed portion are not similar in shape, and the support portion is arranged at a location where, when an imaginary line passing through the center point of the actuator is drawn on the plate surface, the difference between the distance from the center point to the outer shape of the fixed portion intersecting with the imaginary line and the distance from the center point to the outer shape of the actuator intersecting with the imaginary line is greatest, and the support portion has a folded portion which allows the support portion to be superimposed along the outer shape of the actuator.

[0009] According to this configuration, the support portion has a folded portion, which allows the overall length of the support portion to be increased. This reduces the rigidity of the support portion, increasing the amplitude of the bending vibration of the actuator supported by the support portion. This improves pump function. Furthermore, according to this configuration, even if the overall length of the support portion is increased, the size of the support portion can be reduced because the support portion can be folded and stacked. This allows for a more compact pump. Furthermore, according to this configuration, the support portion is provided in the area that would be the largest area occupied by the fixed portion if the support portion were not present. Therefore, according to this configuration, providing the support portion in such a location makes effective use of space, thereby miniaturizing the overall pump.

[0010] In the pump structure relating to the above-mentioned aspect, the support portion has a first end connected to the actuator and a second end connected to the fixed portion, and there is one each of the first end and the second end, and the first end and the second end may be aligned on the virtual line.

[0011] With this configuration, the first end and the second end are aligned on an imaginary line viewed from the center point, so the actuator is stably supported by the fixed portion, and the bending vibration of the actuator is stabilized.

[0012] In the pump structure according to the aforementioned aspect, the support portion may be provided symmetrically with respect to the imaginary line.

[0013] According to this configuration, the structure of the support portion is a branched structure that is symmetrical with respect to the imaginary line, so that the support portion can stably support the actuator, and therefore the bending vibration of the actuator is stabilized.

[0014] In the pump structure according to the above aspect, when the virtual line is taken as a center line, the support portion may be provided in one of regions divided by the center line.

[0015] According to this configuration, the area occupied by the support portion that conforms to the outer shape of the actuator can be reduced, thereby realizing a more compact pump.

[0016] In the pump structure according to the aforementioned aspect, the support portion may be folded in a bellows shape.

[0017] According to this configuration, the overall length of the support portion can be increased. This reduces the rigidity of the support portion. This increases the amplitude of the bending vibration of the actuator supported by the support portion. This improves the pump function. Furthermore, according to this configuration, the support portion is stacked in a bellows shape, so the size of the support portion can be reduced. This allows the pump to be made smaller.

[0018] In the pump structure according to the above aspect, the actuator may be disk-shaped, the outer shape of the fixing portion in the plate surface direction may be rectangular, and the support portion may be arranged at four corners of the fixing portion.

[0019] According to this configuration, the location where the support portion is provided is the largest area that would be occupied by the fixed portion if the support portion were not present. Therefore, according to this configuration, providing the support portion in this location effectively utilizes space and reduces the overall size of the pump. Furthermore, providing the support portion in this position allows the actuator to be supported symmetrically around the center point of the actuator. This allows for the pump to be miniaturized and the bending vibration of the actuator to be stabilized.

[0020] In the pump structure according to the aforementioned aspect, the support portion may be provided with a slit having a substantially uniform width.

[0021] According to this configuration, the aspect ratio of the depth to the width of the slit is substantially constant, which prevents the etching rate from varying depending on the location when the slit is formed by etching.

[0022] In the pump structure according to the above aspect, the support portion may have a rounded portion at an intersection between surfaces orthogonal to the plate surface direction.

[0023] According to this configuration, stress acting on the rounded intersection portion can be reduced, thereby suppressing damage to the support portion. Furthermore, by rounding the intersection portion, the support portion can be made smaller. [Effects of the Invention]

[0024] According to the present invention, it is possible to provide a technology that can improve the characteristics of a pump that pumps a fluid by bending vibration of a plate-shaped piezoelectric actuator and make it possible to reduce the size of the pump. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 illustrates an overview of a pump according to an embodiment. [Figure 2] FIG. 2 is an example of a partially enlarged view of the support portion. [Figure 3] FIG. 3 illustrates an example of the operation of the pump. [Figure 4] FIG. 4 illustrates an outline of a support portion according to a first modified example. [Figure 5] FIG. 5 illustrates an outline of a support portion according to a second modified example. [Figure 6] FIG. 6 illustrates an outline of a support portion according to a third modified example. [Figure 7] FIG. 7 illustrates an outline of a pump according to a fourth modification. DETAILED DESCRIPTION OF THE INVENTION

[0026] §1 Configuration example FIG. 1 illustrates an overview of a pump 1 according to this embodiment. FIG. 1(A) illustrates an overview of a top view of the pump 1. FIG. 1(B) is an overview of a cross-sectional view taken along line AA in FIG. 1(A). As shown in FIGS. 1(A) and 1(B), the pump 1 is provided with a disk-shaped piezoelectric element 2. When a voltage is applied to the piezoelectric element 2, the plate surface vibrates flexibly due to the piezoelectric effect. A similarly disk-shaped diaphragm 3 is fixed to the underside of the piezoelectric element 2. The diaphragm 3 is made of, for example, SOI (Silicon On Insulator) and vibrates in response to the flexural vibration of the piezoelectric element 2. The piezoelectric element 2 and the diaphragm 3 are examples of an "actuator" according to the present disclosure.

[0027] The pump 1 also has a fixed plate 4 arranged around the periphery of the diaphragm 3. The fixed plate 4 has a rectangular shape and is made of, for example, SOI, just like the diaphragm 3. The fixed plate 4 is also provided at a predetermined distance from the diaphragm 3 in the plate surface direction.

[0028] Furthermore, the pump 1 is provided with support parts 5 between the vibration plate 3 and the fixed plate 4. The support parts 5 are connected to both the fixed plate 4 and the vibration plate 3. The support parts 5 support the vibration plate 3 relative to the fixed plate 4. The support parts 5 are provided near the four corners of the rectangular fixed plate 4.

[0029] 1(B), the pump 1 is provided with a movable plate 9 separated from the vibration plate 3 by a gap 10. A substrate 11 is provided on the lower surface of the movable plate 9. The movable plate 9 and the substrate 11 are made of, for example, SOI, the same as the diaphragm 3. Furthermore, a hole 12 and a hole 13 are provided in the center of the movable plate 9 and the substrate 11, respectively.

[0030] FIG. 2 is an example of a partially enlarged view of the support portion 5. As shown in FIG. 2, the support portion 5 branches from an end portion 7 (an example of a "first end portion" in the present disclosure) that is a connection portion with the diaphragm 3, and is provided along the outer shape of the diaphragm 3. The branched support portions 5 are folded back at a folding portion 6 to join together at an end portion 8 (an example of a "second end portion" in the present disclosure) that is a connection portion with the fixed plate 4. The end portion 8 is provided on an extension of an imaginary line connecting the center point of the diaphragm 3 and the end portion 7. The support portion 5 has a shape symmetrical with respect to the imaginary line. The support portion 5 has a slit 14 formed parallel to the outer shape of the diaphragm 3. The width of the slit 14 is approximately constant. The intersection portion (e.g., portion 15) of the surfaces of the support portion 5 that are perpendicular to the plate surface direction is rounded.

[0031] The pump 1 described above is fabricated by the following method: an SOI material is prepared, and the SOI material is etched and bonded, and a predetermined oxide film is then etched and removed with an etchant to form the structure of the pump 1 shown in FIG.

[0032] FIG. 3 illustrates an example of the operation of the pump 1. By controlling the voltage applied to the piezoelectric element 2 (see FIG. 1), the piezoelectric element 2 expands in the planar direction. As a result, as shown in FIG. 3A, the difference in expansion between the piezoelectric element 2 and the diaphragm 3 causes the piezoelectric element 2 and the diaphragm 3 to deform as a whole, with the center portion convex upward (only the diaphragm 3 is shown in FIG. 3A). Fluid is then drawn into the center of the gap 10 through the hole 13 in the substrate 11 and the hole 12 in the movable plate 9 (only the hole 12 is shown in FIG. 3A). Subsequently, by changing the voltage applied to the piezoelectric element 2, the piezoelectric element 2 contracts in the planar direction. As shown in FIG. 3B, the difference in contraction between the piezoelectric element 2 and the diaphragm 3 causes the piezoelectric element 2 and the diaphragm 3 to deform as a whole, with the center portion convex downward. The fluid drawn into the center of the gap 10 then moves in both directions of the gap 10, as shown in FIG. 3B. In this way, the voltage applied to the piezoelectric element 2 is repeatedly controlled to realize a pump function.

[0033] [Actions and Effects] According to the pump 1 described above, the support portion 5 is provided with the folded portion 6, which allows the overall length of the support portion 5 to be increased. This reduces the rigidity of the support portion 5. This increases the amplitude of the bending vibration of the piezoelectric element 2 and the vibration plate 3 supported by the support portion 5. This improves the pump function. Furthermore, according to the pump 1 described above, even if the overall length of the support portion 5 is increased, the size of the support portion 5 can be reduced because the support portion 5 can be folded and stacked. This allows the pump 1 to be made more compact. Furthermore, according to the pump 1 described above, the pump 1 can be made more compact while maintaining the pump function, without reducing the size of the vibration plate 3 itself.

[0034] Furthermore, in the pump 1 described above, the ends 7 and 8 are aligned on an imaginary line when viewed from the center point. Therefore, the piezoelectric element 2 and the diaphragm 3 are stably supported by the fixed plate 4. Therefore, the bending vibration of the piezoelectric element 2 and the diaphragm 3 is stabilized.

[0035] Furthermore, in the pump 1 described above, the structure of the support portion 5 is a branched structure that is symmetrical with respect to an imaginary line that passes through the end portions 7 and 8. Therefore, the support portion 5 can stably support the piezoelectric element 2 and the diaphragm 3. Therefore, the bending vibration of the piezoelectric element 2 and the diaphragm 3 is stabilized.

[0036] Furthermore, in the pump 1 described above, the four corners of the fixed plate 4 where the support parts 5 are provided are the largest areas that would be occupied by the fixed plate 4 if the support parts 5 were not present. Therefore, in the pump 1, by providing the support parts in these locations, space can be effectively utilized. It can be said that this effectively utilizes the space between the piezoelectric element 2 and the vibration plate 3, thereby reducing the overall size of the pump 1. Furthermore, with the pump 1 described above, the support parts 5 are provided at the four corners of the rectangular fixed plate 4, so that the support parts 5 can support the piezoelectric element 2 and the vibration plate 3 symmetrically around the center point of the piezoelectric element 2. This makes it possible to reduce the size of the pump 1 and stabilize the bending vibration of the piezoelectric element 2 and the vibration plate 3.

[0037] Furthermore, in the pump 1 described above, the aspect ratio of the depth to the width of the slit 14 in the support portion 5 is substantially constant. Therefore, when the slit 14 is formed by etching, the occurrence of differences in etching rate depending on the location is suppressed.

[0038] Furthermore, in the pump 1 described above, the intersections (e.g., portions 15) of the surfaces of the support portion 5 that are perpendicular to the plate surface direction are rounded. This reduces the stress acting on these rounded intersections, thereby suppressing damage to the support portion 5. Furthermore, rounding the intersections allows the support portion 5 to be made smaller.

[0039] §2 Variations [Variation 1] FIG. 4 illustrates an outline of a support portion 5A of a pump 1A according to a first modification. The support portion 5A does not branch from end portion 7A, which is the connection portion with the diaphragm 3A, but extends in one direction along the outer shape of the diaphragm 3A. The support portion 5A then folds back in the opposite direction at fold portion 6A and connects to the fixing plate 4A at end portion 8A. End portion 8A is located on an extension of a line segment connecting the center point of the diaphragm 3A and end portion 7A. In other words, if an imaginary line passing through the center of the diaphragm 3A, end portion 7A, and end portion 8A is taken as the center line, the support portion 5A is located in an area to the right of the center line in FIG. 4. This pump 1A also achieves the same effects as the pump 1 according to the embodiment. Furthermore, the pump 1A allows for a reduction in the area occupied by the support portion 5A along the outer shape of the diaphragm 3A. This contributes to the miniaturization of the pump 1A.

[0040] [Variation 2] FIG. 5 illustrates an overview of support portion 5B of pump 1B according to the second modified example. Support portion 5B does not branch off from end portion 7B, which is the connection portion with diaphragm 3B, but extends in one direction along the outer shape of diaphragm 3B. Support portion 5B is then folded back in the opposite direction at folding back portion 6B1 and extends in the opposite direction along the outer shape of diaphragm 3B. Support portion 5B is then folded back again at folding back portion 6B2 and connected to fixing plate 4B at end portion 8B. End portion 8B is located on an extension of the line segment connecting the center point of diaphragm 3B and end portion 7B. In other words, support portion 5B has a bellows-like overlapping shape.

[0041] The pump 1B described above provides the same effects as the pump 1 according to the embodiment. In addition, the pump 1B allows the overall length of the support portion 5B to be longer. This reduces the rigidity of the support portion 5B. This increases the amplitude of the bending vibration of the piezoelectric element 2B and the diaphragm 3B supported by the support portion 5B. This improves the pump function.

[0042] [Variation 3] FIG. 6 illustrates an outline of a support portion 5C of a pump 1C according to a third modified example. The support portion 5C has the same structure as the support portion 5 of the embodiment. However, the support portion 5C is located near two of the four corners of the fixed plate 4C that are diagonally opposite each other. This pump 1C also achieves the same effects as the pump 1 according to the embodiment. Furthermore, the pump 1C allows for a reduction in the area occupied by the support portion 5C. This allows for a further miniaturization of the pump 1C.

[0043] [Variation 4] FIG. 7 illustrates an outline of a pump 1D according to a fourth modification. The shape of a fixing plate 4D of the pump 1D is not rectangular like the fixing plate 4 of the pump 1 according to the embodiment, but is polygonal. The support portion 5D is disposed at a location where, when an imaginary line is drawn through the center point of the diaphragm 3D, the difference between the distance from the center point to the fixed plate 4D where the imaginary line intersects with the fixed plate 4D and the distance from the center point to the outer shape of the diaphragm 3D where the imaginary line intersects with the fixed plate 4D is greatest. This pump 1D also achieves the same effects as the pump 1 according to the embodiment.

[0044] [Other variations] There may be multiple end portions 7, which are the connection portions between the support portion 5 and the diaphragm 3, and multiple end portions 8, which are the connection portions between the support portion 5 and the fixed plate 4. Furthermore, the end portions 7 and 8 do not have to be arranged on an imaginary line passing through the center point of the diaphragm 3. Furthermore, the shapes of the diaphragm 3 and the fixed plate 4 are not limited to the above example, as long as they are similar shapes. Furthermore, the width of the slit 14 in the support portion 5 does not have to be approximately constant. Furthermore, the portion 15 of the support portion 5 (see FIG. 2) etc. does not have to be rounded.

[0045] The embodiments and modifications disclosed above can be combined with each other. [Explanation of symbols]

[0046] 1: Pump 2: Piezoelectric element 3: Vibration plate 4: Fixed plate 5: Support part 6: Folded section 7: Edge 8: Edge 9: Movable plate 11: Substrate 12: Hole 13: Hole 14: Slit 15: part

Claims

1. an actuator having a plate shape, the plate surface of which can be flexurally vibrated by the action of an element having a piezoelectric effect; a fixing portion provided to surround the actuator at a predetermined interval from an outer shape of the actuator in a plate surface direction of the plate surface; a support portion that is integrally provided with the fixed portion and the actuator to connect the fixed portion and the actuator and support the actuator relative to the fixed portion so as to be capable of performing the bending vibration; The actuator and the fixed portion are not similar in shape, the support portion is provided at a position where, when a virtual line is drawn on the plate surface passing through a center point of the actuator, a difference between a distance from the center point to an outer shape of the fixed portion intersecting with the virtual line and a distance from the center point to an outer shape of the actuator intersecting with the virtual line becomes maximum; The support portion is a folded portion that allows the support portion to be folded along an outer shape of the actuator; A first end connected to the actuator; a second end connected to the fixed portion, the first end and the second end are one each; the support portion branches off from the first end portion, and the branched support portions are folded back at the folding back portion to become one with each other at the second end portion, A slit parallel to the outer shape of the actuator is formed in the support portion. Pump structure.

2. The first end and the second end are aligned on the virtual line, 2. A pump structure according to claim 1.

3. The support portion is provided symmetrically with respect to the virtual line.

3. A pump structure according to claim 2.

4. The actuator is disk-shaped, The outer shape of the fixing portion in the plate surface direction is rectangular, The support parts are disposed at the four corners of the fixed part. A pump structure according to any one of claims 1 to 3.

5. The support portion has a rounded intersection between surfaces perpendicular to the plate surface direction. A pump structure according to any one of claims 1 to 4.

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