JP5593907B2 - Piezoelectric pump and manufacturing method thereof - Google Patents

Description

  The present invention relates to a piezoelectric pump using a diaphragm in which a piezoelectric body is bonded on one side, and a method for manufacturing the same.

  As is well known, a piezoelectric pump is configured such that the outer peripheral portion of a diaphragm having a piezoelectric member bonded to one side of a diaphragm is held by a pump casing, and a pump chamber is formed between the pump casing and the diaphragm. An inflow port and an outflow port are connected to the pump chamber, and an alternating voltage is applied to the piezoelectric body to bend and displace the diaphragm, whereby the bending displacement causes the fluid to be sucked from the inflow port into the pump chamber and from the outflow port to Is discharged.

  One of the important performances of this piezoelectric pump is gas discharge pressure or suction pressure. Since this discharge pressure or suction pressure is proportional to the volume change rate of the pump chamber, in order to improve the discharge pressure or the suction pressure when the displacement amount of the diaphragm is the same, the volume of the pump chamber at the time of discharge or the suction pressure is reduced. It is desirable to make it as small as possible.

  Patent Document 1 discloses a piezoelectric pump having a structure in which the shape of the surface of the pump casing facing the diaphragm follows the flexure of the diaphragm during discharge, and the volume of the pump chamber is made as close to zero as possible during the discharge process. Is disclosed. FIG. 10 shows a pump structure disclosed in Patent Document 1, wherein 51 is a pump housing, 52 is a diaphragm, 53 is a pump chamber, 54 is an inlet, 55 is an inflow check valve, 56 is an outlet, 57. Is an outflow check valve. The bottom surface of the pump chamber 53 has a shape that follows the bending shape of the diaphragm 52 during discharge. By applying an alternating voltage to the diaphragm 52, the diaphragm 52 can be bent and displaced, and the bending displacement allows the fluid to be sucked into the pump chamber 53 and discharged from the outlet 56. (A) of FIG. 11 is a suction process, (b) is a discharge process. In this case, the volume change rate of the pump chamber 53 at the time of discharge and suction is increased, and the discharge pressure can be increased.

  In Patent Document 1, a seal member 58 such as an O-ring or a gasket is disposed between the outer peripheral portion of the diaphragm and the pump casing 51 so as not to restrain the outer peripheral portion of the diaphragm 52 as much as possible. However, in this structure, when the diaphragm 52 discharges the fluid, the seal member 58 is bent by the discharge reaction force, so that the discharge pressure may be lowered. On the other hand, in a piezoelectric pump having a structure in which the outer peripheral portion of the diaphragm is directly fixed to the pump housing, the discharge pressure can be increased because no seal member is interposed. However, machining the surface of the pump housing that faces the diaphragm as described above into a shape that follows the displacement of the diaphragm causes an increase in machining cost. In particular, with a pump having a structure in which thin films and thin plate materials are stacked for the purpose of simplifying and thinning the structure, it is actually difficult to produce a pump chamber in a shape that follows the deformation of the diaphragm. .

  Patent Document 2 discloses a piezoelectric pump provided with displacement amount increasing means for increasing the displacement amount of a diaphragm. In FIG. 1, FIG. 6, and FIG. 9 of Patent Document 2, in the initial state (when no voltage is applied), the diaphragm is in surface contact with the pump housing, and the volume of the pump chamber in the initial state is almost the same. An example of a zero state is disclosed. In this case, since the surface of the pump housing facing the diaphragm may be a flat surface, the processing is simple.

  However, if a means for increasing the amount of displacement by a gap or a sealing material is provided on the outer peripheral portion of the diaphragm, the support rigidity of the diaphragm is lowered similarly to Patent Document 1, and it is difficult to obtain a high discharge pressure. In addition, if the diaphragm is bent and displaced in the forward and reverse directions by applying positive and negative alternating voltages to the piezoelectric body, cracks occur in the piezoelectric body because the center of the diaphragm repeatedly collides with the pump housing. May cause problems.

JP-A-3-31589 JP 2001-65461 A

  An object of the present invention is to provide a piezoelectric pump having a high discharge pressure and a method for manufacturing the same without performing special processing on the pump housing.

In order to achieve the above object, the first embodiment of the present invention uses a diaphragm in which a piezoelectric body is bonded to a diaphragm, and an outer peripheral portion of the diaphragm is fixed to a pump casing. A pump chamber is formed between the diaphragm and an inflow port having an inflow check valve and an outflow port having an outflow check valve connected to the pump chamber, and a positive and negative alternating voltage is applied to the piezoelectric body. In the piezoelectric pump for bending and displacing the diaphragm, sucking fluid from the inlet to the pump chamber and discharging fluid from the outlet by the bending displacement, the surface of the pump housing facing the diaphragm Is formed on a substantially flat surface, and the diaphragm is obtained by fixing the piezoelectric body to a main surface on the opposite side of the pump housing among the diaphragms, and the diaphragm is a stranded wire of the piezoelectric body. Material with large expansion coefficient More becomes, the piezoelectric body is bonded and fixed by a thermosetting adhesive on the major surface of the diaphragm, the thermosetting adhesive has a Young's modulus in the cured state is higher than the Young's modulus of the diaphragm, to the piezoelectric body When no voltage is applied, the diaphragm has a shape that is convexly convex in the opposite direction to the pump housing side, and the pump chamber is formed between the pump housing and the diaphragm due to warping. A piezoelectric pump is provided.

The second embodiment of the present invention uses a diaphragm in which a piezoelectric body is bonded to a diaphragm, the outer periphery of the diaphragm is fixed to a pump casing, and the pump is interposed between the pump casing and the diaphragm. The diaphragm is configured by connecting an inflow port having an inflow check valve and an outflow port having an outflow check valve to the pump chamber, and applying a positive and negative alternating voltage to the piezoelectric body. In the piezoelectric pump manufacturing method in which a bending displacement is performed, fluid is sucked into the pump chamber from the inlet and the fluid is discharged from the outlet by the bending displacement, a surface of the pump housing is formed to be a substantially flat surface, The diaphragm is made of a material having a larger linear expansion coefficient than that of the piezoelectric body, and a first step of closely fixing an outer peripheral portion of one main surface of the diaphragm to a flat surface of the pump housing, and after the first step, Other than diaphragm The piezoelectric body in the central portion of the main surface and a second step of bonding and fixing by thermosetting adhesive, the thermosetting adhesive is Young's modulus in the cured state higher than the Young's modulus of the diaphragm, on the diaphragm The piezoelectric body is disposed through a thermosetting adhesive, and the thermosetting adhesive is cured at a high temperature and returned to room temperature, whereby the diaphragm warps in a convex shape in the direction opposite to the pump housing side. A piezoelectric pump manufacturing method, characterized in that the pump chamber is formed between the pump housing and the pump housing by warping of the diaphragm.

  In the present invention, in order to form a pump chamber between the pump housing and the diaphragm, the diaphragm of the diaphragm is warped in a convex direction in the opposite direction to the pump housing instead of forming a recess on the pump housing side. As a shape. Since the pump chamber is formed between the pump housing and the diaphragm due to warping of the diaphragm, the surface of the pump housing may remain flat and no special processing is required. Therefore, it can be easily manufactured even with a pump having a structure in which thin films and thin plate materials are stacked. When the diaphragm is driven and bent toward the pump housing, the amount of warpage of the diaphragm is set so that the central portion of the diaphragm approaches or contacts the flat surface of the pump housing. As a result, the volume of the pump chamber can be made nearly zero during discharge, and a pump with high discharge pressure can be obtained. When the diaphragm is bent and displaced in the forward and reverse directions, the possibility of causing problems such as cracks in the piezoelectric body can be reduced by preventing the central portion of the diaphragm from colliding with the pump housing.

  In the piezoelectric pump according to the present invention, since the outer peripheral portion of the diaphragm is fixed to the pump housing, the displacement amount of the diaphragm is small, but the volume of the pump chamber at the time of discharge is made close to zero so that the discharge pressure is reduced. High pump can be obtained. There are various combinations of material selection for the piezoelectric body and the diaphragm. For example, a unimorph diaphragm may be configured by attaching a single-layer piezoelectric body to one surface of a diaphragm made of a thin metal plate. However, the unimorph diaphragm is flexurally oscillated by restraining a piezoelectric body that expands and contracts in the plane direction with a metal plate, so it is difficult to obtain a large displacement. On the other hand, when a bi-layer type piezoelectric body that flexurally vibrates itself as a piezoelectric body or a laminated piezoelectric body is used and a resin diaphragm such as a resin sheet / resin film is used as a diaphragm to form a bimorph type diaphragm Since the Young's modulus of the resin diaphragm is much smaller than that of the metal plate, the displacement of the piezoelectric body is not constrained and a large displacement can be obtained as compared with the unimorph type. Moreover, since the linear expansion coefficient of the resin diaphragm is larger than that of the metal plate, a large warp can be imparted.

  In the case of a diaphragm in which a bimorph piezoelectric body is bonded to a resin diaphragm with a thermosetting adhesive, the outer periphery of the diaphragm is fixed to the pump housing, and when a positive / reverse alternating voltage is applied to the piezoelectric body, Maximum displacement at the center. The linear expansion coefficient of resin diaphragms is ten to several tens of times larger than that of ceramic piezoelectric bodies. When heat is applied to both of them, the diaphragm warps in a convex shape in the opposite direction to the pump housing due to contraction of the diaphragm. A pump chamber is formed. Therefore, when the diaphragm is displaced in the direction of the pump housing, the gap between the diaphragm and the pump housing becomes less than the warp amount, the pump chamber volume during discharge can be reduced, the discharge pressure can be increased, and the diaphragm Since it does not collide with the pump casing, the impact on the piezoelectric body can be eliminated / mitigated.

  As a method of imparting warpage to the diaphragm (diaphragm), first, the outer periphery of the diaphragm is fixed to the pump housing, and then the piezoelectric body is attached to the main surface of the diaphragm opposite to the pump housing by thermosetting adhesive. After affixing and thermosetting the thermosetting adhesive, a method of giving a warp by returning to normal temperature can be used. In addition to this method, first, a piezoelectric body is attached to the main surface of the diaphragm with a thermosetting adhesive, and the thermosetting adhesive is thermally cured to give warping to the diaphragm, and then the outer periphery of the diaphragm. It is also possible to use a method of fixing to the pump housing. In either case, when the thermosetting adhesive is cured over a predetermined temperature and time and then returned to room temperature, the diaphragm contracts more than the piezoelectric body. Therefore, the diaphragm side is recessed relative to the pump housing. It will warp so that the body side becomes convex. However, in the latter method, since the outer peripheral portion is fixed to the pump housing after the diaphragm is warped, there is a possibility that the diaphragm tension is lowered and the discharge pressure during driving is lowered. On the other hand, in the former method, after restraining the outer peripheral portion of the diaphragm, the center portion of the diaphragm is warped, so that the diaphragm can be warped while maintaining tension, and a large discharge pressure can be obtained. it can.

  As the thermosetting adhesive, it is preferable to use an adhesive having a Young's modulus in a cured state higher than that of the diaphragm, such as an epoxy-based adhesive. This is to prevent the adhesive layer from relaxing the contraction stress due to the difference in linear expansion coefficient between the diaphragm and the piezoelectric body. In addition to the method of attaching the piezoelectric body to the diaphragm with a thermosetting adhesive, the resin diaphragm and the piezoelectric body may be thermally welded. Also in this case, it is possible to generate warpage.

  In the present invention, it is not necessary to warp both the diaphragm and the piezoelectric body constituting the diaphragm, and the piezoelectric body may be substantially flat and only the diaphragm may be warped. At that time, if the thickness of the thermosetting adhesive is formed so that the thickness of the peripheral portion is thicker than the central portion of the piezoelectric body, a large warp can be generated in the diaphragm.

  As a method of fixing the outer peripheral portion of the diaphragm to the pump housing, a thermosetting adhesive may be used, but it is preferable to fix it by a method such as laser welding, heat welding, or adhesion using a room temperature curing adhesive. . That is, a fixing method in which heat is not applied to the central portion of the diaphragm is desirable so that no slack or elongation occurs in the central portion of the diaphragm to which the piezoelectric body is to be bonded.

  As described above, according to the piezoelectric pump of the present invention, the diaphragm of the diaphragm is shaped to be convex in the direction opposite to the pump housing side, and the pump chamber is formed between the diaphragm and the pump housing by warping of the diaphragm. When the diaphragm is driven and bent toward the pump housing, the central part of the diaphragm is close to the flat surface of the pump housing, and the volume of the pump chamber can be reduced to almost zero at the time of discharge. Can be obtained. Since the surface of the pump housing facing the diaphragm is a substantially flat surface, the processing is simple, and even a laminated pump can be easily manufactured. In addition, when the diaphragm is bent and displaced in the forward and reverse directions, the center portion of the diaphragm does not collide with the pump casing, so that a pump with high durability of the piezoelectric body can be obtained.

It is sectional drawing which shows the basic structure of 1st Embodiment of the piezoelectric pump which concerns on this invention. It is a manufacturing process figure of the piezoelectric pump shown in FIG. It is a figure which shows the drive principle of the piezoelectric pump shown in FIG. It is sectional drawing of 2nd Embodiment of the piezoelectric pump which concerns on this invention. 1 is a perspective view of a first embodiment of a piezoelectric pump according to the present invention. FIG. 6 is an exploded perspective view of the piezoelectric pump shown in FIG. 5. It is a top view of the diaphragm of the piezoelectric pump shown in FIG. It is the VIII-VIII sectional view taken on the line of FIG. It is the IX-IX sectional view taken on the line of FIG. It is sectional drawing of a prior art example. It is operation | movement explanatory drawing of a prior art example shown in FIG.

[First Embodiment]
FIG. 1 shows the basic structure of a first embodiment of a piezoelectric pump according to the present invention. This pump P1 is obtained by fixing a diaphragm 10 on a pump housing 1. The diaphragm 10 is obtained by adhering the piezoelectric body 12 to the upper surface of the diaphragm 11 via a thermosetting adhesive 13, and the outer peripheral portion lower surface 11 a of the diaphragm 11 is entirely welded to the upper surface 1 a of the pump housing 1. It is firmly fixed over. Here, the pump housing 1 is formed of a metal material or a resin material, and its upper surface 1a is a flat surface. An inlet 2 having an inflow check valve 3 and an outlet 4 having an outflow check valve 5 are connected to the upper surface 1 a of the pump housing 1. The diaphragm 11 is formed of a resin sheet or resin film having a certain thickness such as PET or polyimide. The piezoelectric body 12 is composed of a two-layer or multilayer ceramic piezoelectric body as disclosed in, for example, WO2008-007634. When an alternating voltage (rectangular wave voltage or AC voltage) is applied between the front and back electrodes of the piezoelectric body 12 and the interlayer electrode, the central region and the peripheral region are bent and deformed in opposite directions, so that the outer peripheral portion is fixedly supported. However, a large displacement can be obtained at the center. The structure of the piezoelectric body 12 is not limited to the above structure, and may be a unimorph diaphragm, but a bimorph diaphragm that can flexurally vibrate by applying an alternating voltage is more preferable.

  When the voltage is not applied, the diaphragm 10 is warped so that the center portion thereof is convex upward, and the pump chamber 6 is formed between the diaphragm 11 and the pump housing 1 by the warp of the diaphragm 10. ing. In FIG. 1, not only the diaphragm 11 but also the piezoelectric body 12 has a shape that is convex upward, but when the thickness of the piezoelectric body 12 is sufficiently thicker than that of the diaphragm 11, the piezoelectric body 12 is substantially flat. Only the diaphragm 11 may be warped.

  2A to 2D show an example of a manufacturing method of the above-described piezoelectric pump P1. 2A shows a state before the diaphragm 11 is arranged on the upper surface 1a of the pump housing 1. FIG. Here, the diaphragm 11 is formed of a flat resin sheet or resin film without warping.

  2B, after the diaphragm 11 is disposed on the upper surface 1a of the pump housing 1, the outer periphery of the diaphragm 11 is irradiated with laser from above, and the outer periphery 11a of the diaphragm 11 is applied to the pump housing 1. A mode that it welds to the upper surface 1a is shown. In addition, when the pump housing | casing 1 is formed with the same material as the diaphragm 11, the pump housing | casing 1 and the diaphragm 11 mutually weld. The laser irradiation range can be set by the shape of the light shielding mask. In laser welding, only the outer peripheral portion 11a of the diaphragm 11 is locally heated, but the central portion of the diaphragm 11 is not heated, so that the central portion of the diaphragm 11 is not slackened or stretched. In addition, as a welding method, if it is a method which can heat only an outer peripheral part locally, not only laser welding but thermal welding may be sufficient.

  FIG. 2C shows a state before the piezoelectric body 12 is bonded to the center of the upper surface of the diaphragm 11 welded onto the pump housing 1. Here, a thermosetting adhesive 13 is applied in advance to the lower surface of the piezoelectric body 12 in a thin film shape. Since the thermosetting adhesive 13 is a viscous liquid at room temperature, the piezoelectric body 12 is attached to the diaphragm 11. Adhesion is maintained by pressing against. At this time, since the lower surface of the diaphragm 11 is supported by the flat upper surface 1a of the pump housing 1, the diaphragm 11 does not bend when pressure is applied from above, and the surface can be bonded without a gap. As the thermosetting adhesive 13, it is preferable to use an adhesive having a higher Young's modulus than the diaphragm 11 such as an epoxy adhesive. The reason for this is to prevent the adhesive layer 13 from relieving stress when contraction stress due to a difference in linear expansion coefficient between the diaphragm 11 and the piezoelectric body 12 described later acts.

  FIG. 2D shows a state after the pump housing 1 in which the piezoelectric body 12 is bonded (uncured state) on the diaphragm 11 as described above is put into a thermosetting furnace and heat treatment is performed. When the thermosetting adhesive 13 is cured, the curing temperature is 60 ° C. to 150 ° C. and the curing time is about 10 minutes to 2 hours. Therefore, the diaphragm 11 is thermally expanded in the thermosetting furnace. The thermosetting adhesive 13 is cured. Thereafter, when the pump casing 1 including the diaphragm 10 is taken out of the thermosetting furnace and returned to room temperature, the diaphragm 11 contracts more greatly than the piezoelectric body 12 due to the difference in linear expansion coefficient between the diaphragm 11 and the piezoelectric body 12, and the diaphragm. 11 becomes the shape which curved upwards convexly. By this warpage, the pump chamber 6 can be formed between the diaphragm 11 and the pump housing 1. The amount of warping of the diaphragm 11 is set so that the central portion of the diaphragm 11 approaches or contacts the surface of the pump housing 1 when the piezoelectric body 12 is bent toward the pump housing 1 side. The amount of warpage can be variously designed according to the material, size, heat treatment conditions, and the like of the piezoelectric body 12 and the diaphragm 11.

  3A to 3C show the operation of the piezoelectric pump P1 manufactured by the above method. 3A shows an initial state (when no voltage is applied), and a pump chamber 6 is formed between the pump housing 1 and the diaphragm 11 due to warping of the diaphragm 11. The pump chamber 6 is connected to the inlet 2 and the outlet 4.

  FIG. 3B shows a state in which a voltage is applied to the piezoelectric body 12 so as to deform it so that its central portion is convex upward. When the piezoelectric body 12 is bent and deformed upward, the diaphragm 11 is also integrally deformed, and the volume of the pump chamber 6 is increased. Therefore, the inflow side check valve 3 is automatically opened, and the fluid is sucked into the pump chamber 6 from the inlet 2. At this time, the outflow check valve 5 remains closed.

  FIG. 3C shows a state in which a voltage in the direction opposite to that of FIG. As a result, the diaphragm including the diaphragm 11 is deformed in the flat direction, and the gap between the diaphragm 11 and the upper surface 1a of the pump housing 1 is substantially zero, that is, the volume of the pump chamber 6 is substantially zero. Therefore, the outflow check valve 5 is opened by the pressure of the pushed-out fluid, and the fluid is discharged from the outlet 4. Since the volume of the pump chamber 6 at the time of discharge is almost zero, the volume change rate of the pump chamber at the time of suction increases, and a pump with a high discharge pressure can be realized.

  Thereafter, by applying positive and negative alternating voltages to the piezoelectric body 12, the operations of (A) to (C) in FIG. 3 are repeated, fluid is sucked from the inlet 2, and high-pressure fluid is discharged from the outlet 4. be able to.

  PZT (linear expansion coefficient: about 1 ppm / ° C.) having a thickness of 300 μm is used as the piezoelectric body 12, an epoxy adhesive having a thickness of 30 μm is used as the thermosetting adhesive 13, and a PET resin film having a thickness of 75 μm is used as the diaphragm 11. Linear expansion coefficient: about 20 ppm / ° C., and when the inner diameter dimension D of the non-welded portion (pump chamber 6) between the pump housing 1 and the diaphragm 11 is 15 mm, the linear expansion between the piezoelectric body 12 and the diaphragm 11 A warp H of about 20 μm can be obtained due to the coefficient difference (see FIG. 1). In such a piezoelectric pump P1, when a voltage of ± 6 V is applied to the piezoelectric body, it is possible to obtain a displacement of about 15 μm in the forward and reverse directions at the center. Therefore, the gap between the diaphragm and the pump casing at the time of discharge becomes 5 μm or less, the pump chamber volume can be made substantially zero, and the diaphragm can be prevented from colliding with the pump casing. When air was used as the fluid, when the piezoelectric body was driven at ± 6 V and 1 Hz, the discharge flow rate was 1.4 μl / s and the discharge pressure was 7 kPa. On the other hand, when methanol was used as the fluid, the discharge flow rate was 1.4 μl / s and the discharge pressure was 40 kPa. In this way, a pump with a very high discharge pressure could be realized.

[Second Embodiment]
FIG. 4 shows a second embodiment of the piezoelectric pump according to the present invention. This pump P2 is the first except that the thickness of the thermosetting adhesive 13 for bonding the piezoelectric body 12 to the diaphragm 11 is formed so that the peripheral portion is thicker than the central portion of the piezoelectric body 12. This is the same as the pump P1 of the embodiment. That is, the thickness t 1 of the thermosetting adhesive 13 in the peripheral portion of the piezoelectric body 12 is thicker than the thickness t 2 of the thermosetting adhesive 13 in the central portion of the piezoelectric body 12. In this embodiment, even when the piezoelectric body 12 has a thickness that does not easily warp, the diaphragm 11 can be warped due to the thickness difference of the thermosetting adhesive 13.

-Example-
5 to 9 show a first embodiment of a piezoelectric pump according to the present invention. The piezoelectric pump P3 is obtained by laminating a base plate 20, a base sheet 21, a diaphragm 22, a first frame body 23, and a second frame body 24 in this order and bonding or welding them. A piezoelectric body 25 is bonded to the center portion of the diaphragm 22, and a terminal block 30 having external terminals 31 and 32 is provided at one corner portion of the base plate 20.

  The base plate 20 is made of, for example, a stainless steel plate having a thickness of 0.5 mm in order to ensure strength. A plurality of mounting holes 20 a are formed in the periphery of the base plate 20. The base material sheet 21, the diaphragm 22, the first frame body 23, and the second frame body 24 are made of, for example, a PET resin film having a thickness of 75 μm. Therefore, this piezoelectric pump is configured as an ultra-thin pump having an overall thickness of about 1 mm.

  The base sheet 21 is closely fixed on the entire surface of the base plate 20 to constitute the pump casing of the present invention. An inflow passage 21a and an outflow passage 21b extending in the radial direction from the center are formed through the portion of the base sheet 21 corresponding to the pump chamber. The flow paths 21a and 21b are configured with narrow slits of about 0.5 mm, for example.

  As shown in FIG. 7, the diaphragm 22 has a region outside the circular region 22 a serving as a pump chamber that is tightly fixed on the base sheet 21. In the area outside the circular area 22a of the diaphragm 22, an inflow hole 22b is formed at a position corresponding to the outer end of the inflow path 21a of the base sheet 21, and a position corresponding to the outer end of the outflow path 21b. The outflow side valve hole 22c is formed in.

  The first frame body 23 is closely fixed to the periphery of the diaphragm 22, and the second frame body 24 is firmly fixed to the first frame body 23. Openings 23 a and 24 a larger than the piezoelectric body 25 are formed inside the first frame body 23 and the second frame body 24. In the peripheral frame portion of the first frame body 23, through holes 23b and 23c for forming a valve chamber are formed at positions facing the inflow hole 22b and the outflow side valve hole 22c of the diaphragm 22. The check valves 27 and 28 are accommodated in the through holes 23b and 23c, respectively. An inflow side valve hole 24b and an outflow hole 24c are formed in the peripheral frame portion of the second frame 24 at positions facing the inflow hole 22b and the outflow side valve hole 22c of the diaphragm 22, respectively. The inflow side check valve 27 always closes the inflow side valve hole 24 b of the second frame 24, and the outflow side check valve 28 always closes the outflow side valve hole 22 c of the diaphragm 22.

  A rectangular piezoelectric body 25 is bonded to the center of the upper surface of the diaphragm 22 by a thermosetting adhesive (not shown), and the diaphragm 22 and the piezoelectric body 25 constitute a diaphragm 26. The adhesion of the piezoelectric body 25 to the diaphragm 22 is performed after the base sheet 21, the diaphragm 22, the first frame body 23, and the second frame body 24 are fixed to the base plate 20. That is, the piezoelectric body 25 is bonded after the peripheral region excluding the deformable circular region 22a of the diaphragm 22 is fixed to the base material sheet 21. Due to the difference in linear expansion coefficient between the piezoelectric body 25 and the diaphragm 22, a convex warpage is imparted to the diaphragm 26 (see FIGS. 8 and 9). Due to this warpage, a pump chamber 29 is formed between the diaphragm 22 and the base sheet 21.

  One corner portion of the base sheet 21, the diaphragm 22, the first frame body 23, and the second frame body 24 excluding the base plate 20 is cut out, and the terminal block 30 is formed on the base plate 20 through the cutout portions. Is fixed. A pair of external terminals 31 and 32 are fixed to the terminal block 30, and an alternating voltage can be applied to the piezoelectric body 25 by contacting the external terminals 31 and 32 with an electrode (not shown) of the piezoelectric body 25. .

  In the present embodiment, the piezoelectric body 25 is formed in a quadrangular shape, and its area is wider than the circular region 22a constituting the pump chamber. That is, the outer peripheral portion of the piezoelectric body 25 cannot be displaced, but when the electrodes are formed in a circular shape as described in the above-mentioned WO 2008-007634, the outer peripheral corner portion is hardly deformed, so there is no problem.

  In the above embodiment, the base material sheet 21 constituting the plane of the pump housing is formed with the inflow channel 21a and the outflow channel 21b extending in the radial direction from the center, but this is a viscous fluid such as a liquid. This is a structure suitable for flowing the water. When flowing a relatively low viscosity fluid such as air, the inflow and outflow channels on the plane of the pump housing can be omitted if the inflow and outflow holes are located within the diaphragm displacement area. It is also possible to do.

P1 to P3 Piezoelectric pump 1 Pump housing 1a Upper surface (flat surface)
2 Inlet 3 Inlet check valve 4 Outlet 5 Outlet check valve 6 Pump chamber 10 Diaphragm 11 Diaphragm 11a Welding part 12 Piezoelectric 13 Thermosetting adhesive

Claims (7)

A diaphragm with a piezoelectric material bonded to the diaphragm is used, the outer periphery of the diaphragm is fixed to the pump housing, a pump chamber is formed between the pump housing and the diaphragm, and flows into the pump chamber An inflow port having a side check valve and an outflow port having an outflow check valve are connected, and the diaphragm is bent and displaced by applying a positive and negative alternating voltage to the piezoelectric body. In the piezoelectric pump that sucks fluid into the pump chamber from the inlet and discharges fluid from the outlet,
The surface of the pump housing facing the diaphragm is formed in a substantially flat surface,
The diaphragm is a diaphragm in which the piezoelectric body is fixed to a main surface opposite to the pump housing among the diaphragms,
The diaphragm is made of a material having a larger linear expansion coefficient than the piezoelectric body,
The piezoelectric body is bonded and fixed to the main surface of the diaphragm with a thermosetting adhesive,
The thermosetting adhesive has a higher Young's modulus in the cured state than the Young's modulus of the diaphragm,
When no voltage is applied to the piezoelectric body, the diaphragm has a shape that is curved in a convex shape in the opposite direction to the pump housing side,
The piezoelectric pump characterized in that the pump chamber is formed between the pump housing and the diaphragm due to warping of the diaphragm.   The amount of warpage of the diaphragm is set such that when the diaphragm is bent toward the pump casing, the central portion of the diaphragm approaches or contacts the surface of the pump casing. Item 2. The piezoelectric pump according to Item 1. The piezoelectric body is bonded and fixed to the main surface of the diaphragm with a thermosetting adhesive,
3. The piezoelectric pump according to claim 1, wherein the thermosetting adhesive is formed such that a thickness of a peripheral portion is thicker than a central portion of the piezoelectric body. The diaphragm according to any one of claims 1 to 3 , wherein the diaphragm is a resin diaphragm, and the piezoelectric body is a bimorph piezoelectric body that flexurally vibrates itself when the alternating voltage is applied. Piezoelectric pump. A diaphragm with a piezoelectric material bonded to the diaphragm is used, the outer periphery of the diaphragm is fixed to the pump housing, a pump chamber is formed between the pump housing and the diaphragm, and flows into the pump chamber An inflow port having a side check valve and an outflow port having an outflow check valve are connected, and the diaphragm is bent and displaced by applying a positive and negative alternating voltage to the piezoelectric body. In a method for manufacturing a piezoelectric pump that sucks fluid from an inlet into a pump chamber and discharges fluid from the outlet,
The surface of the pump housing is formed in a substantially flat surface, and the diaphragm is made of a material having a larger linear expansion coefficient than the piezoelectric body,
A first step of tightly fixing the outer peripheral portion of one main surface of the diaphragm to the flat surface of the pump housing;
After the first step, the second step of bonding and fixing the piezoelectric body to the center of the other main surface of the diaphragm with a thermosetting adhesive, the thermosetting adhesive having a Young's modulus in a cured state The diaphragm has a pump modulus higher than the Young's modulus of the diaphragm by placing a piezoelectric body on the diaphragm via a thermosetting adhesive, curing the thermosetting adhesive at a high temperature, and returning to normal temperature. Having a second step that is curved in a convex shape in the opposite direction to the body side,
A method of manufacturing a piezoelectric pump, wherein the pump chamber is formed between the pump housing and the diaphragm by warping of the diaphragm. The amount of warpage of the diaphragm is set such that when the diaphragm is bent toward the pump casing, the central portion of the diaphragm approaches or contacts the surface of the pump casing. Item 6. A method for manufacturing a piezoelectric pump according to Item 5 . The piezoelectric pump according to claim 5 or 6 , wherein, in the second step, the thermosetting adhesive is formed so that a thickness of a peripheral portion is thicker than a central portion of the piezoelectric body. Method.

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