JP2010190211A - Jointed body and fluid device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a jointed body constituted by jointing a plurality of members with different linear expansion coefficients to each other, having enhanced rigidity as a whole and preventing peeling with respect to thermal stress even if the jointed body is small and thin, and a fluid device. <P>SOLUTION: A piezoelectric pump 101 applies pressure to fluid within a pump chamber 52 by using bending vibration of a piezoelectric vibrator 65 to discharge fluid. The piezoelectric pump 101 includes a highly rigid plate 60C, a jointing layer 60A and a pump chamber body 70. The highly rigid plate 60C is made of stainless steel. The jointing layer 60A and pump body 70 is made of PET. The jointing layer 60A is formed on a main face of the highly rigid plate 60C. The linear expansion coefficient of each of the jointing layer 60A and the pump chamber body 70 is set larger than that of the highly rigid plate 60C. The pump chamber body 70 has lower rigidity compared to the highly rigid plate 60C, and is jointed to the jointing layer 60A in the position where at least part of an outer end of the pump chamber body 70 is made to abut on an inner side from the end of the jointing layer 60A. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a joined body formed by joining a plurality of members having different linear expansion coefficients, and a fluid device such as a piezoelectric pump in which a plurality of members having different linear expansion coefficients are joined to form a pump chamber.

  The piezoelectric pump uses a piezoelectric vibrator to vibrate the diaphragm and discharges fluid in the pump chamber. In general, a piezoelectric pump can be configured to be small and thin and has low power consumption. Therefore, it can be used as a fuel transportation pump for a fuel cell (see, for example, Patent Document 1).

WO2008 / 007634 Publication

  In the conventional piezoelectric pump, the constituent members of the pump chamber excluding the piezoelectric element may be made of resin or the like. In this case, since the resin has low rigidity, the pump chamber is slightly deformed by the change in fluid pressure accompanying the vibration of the diaphragm, and the pressure loss of the fluid is increased, so that the discharge performance of the piezoelectric pump is impaired.

  Therefore, it is conceivable to increase the rigidity of the pump chamber by configuring the pump chamber with a thick member, but in that case, the characteristics of the piezoelectric pump that are small and thin are impaired. Although it is conceivable that the entire pump chamber is made of a high-rigidity material, resin is easy to mold, and it is difficult to configure the entire pump chamber that requires complicated shape molding from materials other than resin because of cost. .

  Therefore, it is conceivable to make the pump chamber highly rigid by forming the pump chamber by bonding a resin member and a highly rigid material having higher rigidity than the resin. However, when a resin member and a high-rigidity material having different materials are bonded together, there arises a problem that the different material bonding surface is easily peeled off due to a difference in linear expansion coefficient. Specifically, peeling occurs when, for example, thermal stress is applied to the bonded surface of different materials. Such a problem of peeling similarly occurs even in a joined body or a fluid device having a configuration in which two types of members having different linear expansion coefficients are joined.

  Therefore, the present invention provides a joined body that enhances the rigidity of the whole joined body formed by joining a plurality of members having different linear expansion coefficients, and is less likely to be peeled off against thermal stress even in a small and thin shape. The purpose is to provide fluid equipment.

The present invention is a joined body in which a first joining member and a second joining member are joined. The second joining member is more rigid than the first joining member. The second bonding member has a bonding layer formed on the main surface. The bonding layer has a linear expansion coefficient different from that of the second bonding member. The first bonding member has a linear expansion coefficient different from that of the second bonding member, and is bonded to the bonding layer at a position where at least a part of the outer end is inward of the end of the bonding layer.
In particular, the linear expansion coefficient of the bonding layer and the linear expansion coefficient of the first bonding member are preferably larger than the linear expansion coefficient of the second bonding member.
In addition, the present invention is a fluid device in which a fluid device body and a rigid plate are joined to form a fluid device, and pressure is applied to the fluid in the fluid device to discharge the fluid. The fluid device corresponds to a joined body, the fluid device body corresponds to a first joining member, and the rigid plate corresponds to a second joining member.

  In this structure, by bonding the first bonding member and the second bonding member, the rigidity of the bonded body can be increased without increasing the thickness of the bonded body. Moreover, if it is fluid apparatuses, such as a piezoelectric pump, the fluid discharge performance can be improved.

  Further, the first bonding member having a linear expansion coefficient different from the linear expansion coefficient of the second bonding member is similarly different from the linear expansion coefficient of the second bonding member, and the expansion / contraction direction when heat is applied is also different. Since it joins to the joining layer which has the linear expansion coefficient which becomes the same direction as the 1st joining member, when the 1st joining member and the 2nd joining member are directly connected, the thermal stress which acts on the interface of both is connected. The thermal stress acting on the bonding surface is suppressed. On the other hand, in the region facing the bonding portion of the first bonding member in the bonding surface of the bonding layer and the second bonding member, the first bonding member is substantially connected to the second bonding member. Equivalent thermal stress acts. However, since the outer end of the first bonding member is bonded to the bonding layer at a position that is inward of the end of the bonding layer, a different material is used than when the first bonding member is directly connected to the second bonding member. Peeling of the bonded surface is unlikely to occur.

  FIG. 1 is a diagram for explaining the operation. The comparative configuration example shown in FIG. 1A is a configuration in which the end of the different material bonding surface of the bonding layer 3A and the second bonding member 2A overlaps the outer end of the first bonding member 1A. In this case, the force acting on the region facing the first bonding member 1A is concentrated on the edge of the different material bonding surface, and there is a high risk that the separation proceeds along the different material bonding surface. On the other hand, in this configuration example shown in FIG. 1B, the end of the different material bonding surface of the bonding layer 3B and the second bonding member 2B is separated from the outer end of the first bonding member 1B. In this case, the end of the different material bonding surface is separated outward from the region facing the first bonding member 1B. Then, the force acting on the region facing the first bonding member 1B is dispersed over the entire region, and therefore, the separation of the bonded surface of the different materials hardly proceeds.

  The first joining member of the present invention preferably has a stepped outer end, and the outer end of the main surface opposite to the main surface to be joined to the joining layer of the first joining member is the first joining. It is good to be located inside the outer end of the main surface joined to the joining layer of the member. This is, for example, a structure in which the outer end of the pump chamber body has a stepped shape. Thereby, since the outermost end of the pump chamber body becomes substantially thin, thermal stress is suppressed, and peeling of the bonded surface of the different materials can be further suppressed.

  It is preferable that the bonding layer of the present invention and the first bonding member have the same linear expansion coefficient. Thereby, a thermal stress can be suppressed significantly and peeling of a different material pasting surface can be controlled more.

  According to this invention, by bonding the first joining member and the second joining member, the rigidity of the joined body can be increased without increasing the thickness of the first joining member, and a fluid device such as a piezoelectric pump can be obtained. If so, the discharge performance of the piezoelectric pump can be improved while being small and thin. In addition, the first bonding member having a linear expansion coefficient different from the linear expansion coefficient of the second bonding member is the second through a bonding layer having a linear expansion coefficient different from the linear expansion coefficient of the second bonding member. Since at least a part of the outer end of the first joining member is joined to the joining layer at a position that is inward of the end of the joining layer, peeling due to thermal stress is caused on the bonding surface of each part. It becomes difficult to progress.

It is a figure explaining the example of an operation of the present invention. It is a top view of the piezoelectric pump concerning a 1st embodiment. It is a disassembled perspective view of the piezoelectric pump which concerns on 1st Embodiment. It is sectional drawing of the piezoelectric pump which concerns on 1st Embodiment. It is a figure explaining the simulation result by a thermal stress test. It is a figure explaining schematic structure of the piezoelectric pump concerning a 2nd embodiment. It is a figure explaining schematic structure of the piezoelectric pump concerning a 3rd embodiment.

  Hereinafter, as an embodiment of the joined body and the fluid device of the present invention, the present invention will be described taking a piezoelectric pump as an example. The first joint portion and the fluid device main body of the present invention correspond to a pump chamber described later, and the second joint member and the rigid plate correspond to a pump chamber top plate described later.

<< First Embodiment >>
FIG. 2 is a plan view of the piezoelectric pump 101 according to the first embodiment, and FIG. 3 is an exploded perspective view of the piezoelectric pump 101.

  The piezoelectric pump 101 includes a rectangular piezoelectric vibrator 65, a pump chamber main body 70 on which the piezoelectric vibrator 65 is mounted, and a pump chamber top plate 60 on which the pump chamber main body 70 is mounted. The pump chamber body 70 includes a circular pump chamber 52, an inlet 51 that supplies fluid to the pump chamber 52, and an outlet 53 that discharges fluid from the pump chamber. The two electrodes of the piezoelectric vibrator 65 are electrically connected to the connector 68, and the piezoelectric vibrator 65 vibrates when an AC voltage is applied.

  As shown in FIG. 3, the pump chamber body 70 is configured by laminating a flow path plate 62, a pump chamber plate 63, a diaphragm 64, a valve chamber plate 66, and a bottom plate 67, each of which is a PET sheet. A flow path plate 62 is disposed on the top of the pump chamber top plate 60. A channel groove 59 is formed in the channel plate 62 from the central position of the pump chamber 52 to the inlet 51 or the outlet 53. A pump chamber plate 63 is disposed above the flow path plate 62. A pump chamber 52 is formed in the pump chamber plate 63 by a substantially circular cut. A diaphragm 64 is disposed above the pump chamber plate 63. A piezoelectric vibrator 65 of PZT (lead zirconate titanate) is attached to the upper part of the diaphragm 64. A valve chamber plate 66 is disposed on the upper part of the diaphragm 64. Two valve chamber openings H are formed in the valve chamber plate 66, and check valves 54 and 55 are arranged inside the two valve chamber openings H, respectively. The check valve 54 prevents the fluid from flowing back from the inlet 51 to the outside of the pump chamber, and the check valve 55 prevents the fluid from flowing back from the discharge port 53 into the pump chamber. A bottom plate 67 is disposed above the valve chamber plate 66. Inside the pump chamber 52, a liquid holding member 56 that holds the liquid in a gap with the pump chamber 52 by capillary action is disposed in an unfixed state. The liquid holding member 56 is circular smaller than the pump chamber 52, and is formed by processing an opening 57 in the center of the PET sheet.

The dimensions and overall dimensions of the piezoelectric pump 101 are as follows.
Pump chamber 52: diameter 14.5 mm x thickness 0.075 mm
Piezoelectric vibrator 65: 17 mm x thickness 0.3 mm
Liquid holding member 56: diameter 14.0 mm × thickness 0.06 mm
Diaphragm 64: 19.4 mm × 28.8 mm × thickness 0.075 mm
The entire piezoelectric pump 101: 24 mm × 33 mm × thickness 1.325 mm
When the piezoelectric pump 101 is actually used, the pump chamber top plate 60 is used on the upper surface side and the bottom plate 67 is used on the lower surface side. Therefore, in FIG. 3, the names of the components located in the lowermost layer and the uppermost layer are “pump chamber top plate” and “bottom plate”. In order to use this piezoelectric pump 101, an alternating voltage is applied to cause the piezoelectric vibrator 65 to bend and vibrate to bend the diaphragm 64, thereby repeating the volume expansion / contraction of the pump chamber 52. Then, fluid flows in from the inlet 51 when the pump chamber 52 is expanded, and fluid in the pump chamber 52 is discharged from the outlet 53 when the pump chamber 52 contracts.

  FIG. 4 is a cross-sectional view of the piezoelectric pump 101. 4A is a cross-sectional view of a vertical plane passing through the flow channel groove 59, and FIG. 4B is a vertical view that passes through the center of the pump chamber 52 and is substantially orthogonal to the direction in which the flow channel groove 59 extends. It is sectional drawing in a surface.

  The pump chamber top plate 60 includes a high-rigidity plate 60C obtained by processing highly rigid stainless steel, a bonding layer 60A obtained by processing a PET sheet, and an adhesive layer 60B between the high-rigidity plate 60C and the bonding layer 60A. . The thickness of the adhesive layer 60B is 20 to 80 μm, the thickness of the high-rigidity plate 60C is 200 to 800 μm, and the thickness of the bonding layer 60A is 30 to 100 μm.

  The pump chamber top plate 60 is formed by applying an adhesive on the high-rigidity plate 60C by screen printing or the like to form the adhesive layer 60B, and then bonding the bonding layer 60A and thermally curing or UV curing the adhesive. To do. In addition, the adhesive layer 60B may be applied to the bonding layer 60A in advance to be in a temporarily cured state, and then the high rigidity plate 60C may be bonded by a laminating method to constitute the pump chamber top plate 60.

  Here, the pump chamber main body 70 is bonded to a position offset by about 1 mm inside from the end of the bonding layer 60 </ b> A of the pump chamber top plate 60, and the pump chamber top plate 60 is about 1 mm from the main surface side of the pump chamber main plate 70. It protrudes outward from the side. This configuration may be realized by bonding the bonding layer 60A of the pump chamber top plate 60 to the pump chamber main body 70 formed in advance, and the pump is formed on the bonding layer 60A of the pump chamber top plate 60. You may implement | achieve by joining the member which comprises the chamber main body 70 in order. Here, the pump chamber body 70 and the pump chamber top plate 60 are bonded by various bonding methods, but the present invention is more effective particularly when bonded by a bonding method in which a steep thermal history such as laser welding is applied. It is.

  Since the high rigidity plate 60C is provided on the pump chamber top plate 60 as described above, the rigidity of the entire pump chamber can be increased without increasing the thickness of the pump chamber main body 70, and the discharge performance of the piezoelectric pump 101 can be improved.

  In addition, since the pump chamber body 70 is bonded to the bonding layer 60A of the pump chamber top plate 60 made of the same PET sheet, the linear expansion coefficients of both are equal and the thermal stress acting on the welded interface between the two is This is significantly less than when the chamber body 70 is directly joined to the high-rigidity plate 60C.

  The bonding layer 60 </ b> A may be made of a material other than the PET sheet, but may be any material having a linear expansion coefficient whose expansion / contraction direction when heat is applied is the same as that of the pump chamber 70. In particular, it is preferable that the linear expansion coefficient is larger than the stainless steel of the high-rigidity plate 60C, and is closer to the linear expansion coefficient of the PET sheet than stainless steel.

  On the other hand, since the linear expansion coefficient is different between the high-rigidity plate 60C and the bonding layer 60A, the pump chamber main body 70 is directly connected to the high-rigidity plate 60C in the region facing the pump chamber main body 70 in the adhesive layer 60B. A thermal stress substantially equivalent to the above will act. However, since the pump chamber body 70 is offset from the end of the bonding layer 60A, the adhesive layer 60B is less likely to peel than when the pump chamber body 70 is directly connected to the high-rigidity plate 60C. Therefore, even if the pump chamber top plate 60 is made of a different material, the piezoelectric pump 101 has high stress resistance against thermal stress acting on the bonding surfaces of the two.

  Next, a simulation result by FEM analysis in which a thermal stress test is performed using a piezoelectric pump will be described.

The piezoelectric pump has the following specifications.
・ Each layer thickness of the pump chamber body: 75μm
・ Joint layer of pump chamber top plate: 50μm
・ High rigidity plate of the pump chamber top plate: 500μm
The thermal stress test was made as follows.
Thermal history: + 260 ° C → + 20 ° C or + 260 ° C → -40 ° C
And the thermal stress test was performed by changing the conditions of the offset amount between the pump chamber top plate and the pump chamber main body in the piezoelectric pump, and the maximum value of the stress generated in the pump chamber top plate after each test was compared.

  FIG. 5 is a diagram for explaining the relationship between the offset amount and the stress.

  In the thermal stress test conducted with a thermal history of + 260 ° C. → + 20 ° C., the offset amount was 0 mm, that is, the maximum was 30 MPa in the case of the comparative configuration of FIG. When the thickness was 1.0 mm, the stress was reduced by about 95% compared to the comparative configuration.

  In the thermal stress test performed with a thermal history of + 260 ° C. → −40 ° C., a similar tendency is observed, and the offset amount is 0 mm, that is, the maximum is 37 MPa in the case of the comparative configuration in FIG. 1, and the offset amount is increased. The stress was reduced as much as possible, and when the offset amount was 1.0 mm, the stress was reduced by about 95% compared to the comparative configuration.

  In this way, even if different types of materials are bonded, it is possible to suppress thermal stress by taking an offset. Therefore, the present invention can suppress peeling at the bonded surfaces of different materials, and increase the thermal stress resistance of the piezoelectric pump. Was confirmed in the simulation.

<< Second Embodiment >>
FIG. 6 is a cross-sectional view of the piezoelectric pump 102 according to the second embodiment. Unlike the piezoelectric pump 101, the piezoelectric pump 102 has a stepped outer end of the pump chamber body 70. Specifically, the outer shape of the valve chamber plate 66 and the bottom plate 67 is made smaller than that of the piezoelectric pump 101, and the outer ends of the valve chamber plate 66 and the bottom plate 67 are connected to the flow path plate 62 and the pump chamber plate 63. It arrange | positions inside the outer side edge with the diaphragm 64. FIG.

  Thus, by making the pump chamber main body 70 stepped, the thickness of the outermost end of the pump chamber main body 70 that contributes to thermal stress at the joining position of the pump chamber main body 70 and the pump chamber top plate 60 is stepped. Compared with the piezoelectric pump 101 of the first embodiment that does not have the Therefore, thermal stress acting on the adhesive layer 60B of the pump chamber top plate 60 can be suppressed, and peeling of the adhesive layer 60B can be further suppressed.

  Here, a two-stage shape is formed with the boundary between the diaphragm 64 and the valve chamber plate 66 as a boundary. However, a multi-stage configuration may be adopted, and a boundary between the flow path plate 62 and the pump chamber plate 63 may be used. A step shape, or a step shape with the boundary between the pump chamber plate 63 and the diaphragm 64 as a boundary, is preferable because the thermal stress can be further suppressed.

<< Third Embodiment >>
FIG. 7 is a schematic top view of the piezoelectric pump 103 according to the third embodiment. In the piezoelectric pump 103, the dimension of the pump chamber top plate 60 in the longitudinal direction of the main surface is equal to the dimension of the pump chamber main body 70, and the size of the pump chamber top plate 60 in the short direction of the main surface is also equal to the dimension of the pump chamber main body 70. . The four corners of the pump chamber main body 70 corresponding to the corners of the main surface of the pump chamber top plate 60 are chamfered, and the pump chamber main body 70 is joined to the inside of the joining layer 60A at the four corners.

  Even in such a configuration, since the dissimilar material bonding surface of the high-rigidity plate 60C and the bonding layer 60A is difficult to peel off at least at the corner portion of the main surface of the pump chamber top plate 60, the thermal stress of the piezoelectric pump 103 is reduced. Increases resistance.

DESCRIPTION OF SYMBOLS 101,102,103 ... Piezoelectric pump 1A, 1B ... 1st joining member 2A, 2B ... 2nd joining member 3A, 3B, 60A ... Joining layer 51 ... Inflow port 52 ... Pump chamber 53 ... Discharge port 54, 55 ... Check valve 56 ... Liquid holding member 57 ... Opening 59 ... Channel groove 60 ... Pump chamber top plate 60B ... Adhesive layer 60C ... High rigidity plate 62 ... Channel plate 63 ... Pump chamber plate 64 ... Diaphragm 65 ... Piezoelectric Vibrator 66 ... Valve chamber plate 67 ... Bottom plate 68 ... Connector 70 ... Pump chamber body H ... Valve chamber opening

Claims (8)

A joined body obtained by joining a first joining member and a second joining member having higher rigidity than the first joining member,
The second bonding member is formed on the main surface with a bonding layer having a linear expansion coefficient different from the linear expansion coefficient of the second bonding member,
The first bonding member has a linear expansion coefficient different from the linear expansion coefficient of the second bonding member, and is bonded to the bonding layer at a position where at least a part of the outer end is inward of the end of the bonding layer. To join. A joined body obtained by joining the first joining member and the second joining member having higher rigidity than the first joining member,
In the second bonding member, a bonding layer having a linear expansion coefficient larger than the linear expansion coefficient of the second bonding member is formed on the main surface,
The first joining member is lower in rigidity than the second joining member, has a linear expansion coefficient larger than that of the second joining member, and at least a part of an outer end thereof is the joining member. A joined body joined to the joining layer at a position hitting the inner side of the end of the layer.   The outer end of the first bonding member has a step shape, and the outer end of the main surface opposite to the main surface to be bonded to the bonding layer of the first bonding member is the first bonding member of the first bonding member. The joined body according to claim 1, wherein the joined body is located on an inner side than an outer end of a main surface joined to the joining layer.   The joined body according to any one of claims 1 to 3, wherein the joining layer and the first joining member have an equivalent linear expansion coefficient. The fluid device main body and a rigid plate having higher rigidity than the fluid device main body are joined to form a fluid device chamber, and the fluid device chamber discharges the fluid by applying pressure to the fluid in the fluid device chamber. And
In the rigid plate, a bonding layer having a linear expansion coefficient larger than the linear expansion coefficient of the rigid plate is formed on the main surface,
The fluid device body is lower in rigidity than the rigid plate, has a linear expansion coefficient larger than the linear expansion coefficient of the rigid plate, and a position where at least a part of the outer end is inward of the end of the bonding layer A fluid device which is bonded to the bonding layer.   The fluid device main body has a stepped outer end, and the outer end of the main surface opposite to the main surface bonded to the bonding layer of the fluid device main body is bonded to the bonding layer of the fluid device main body. The fluid device according to claim 5, wherein the fluid device is located inside an outer end of the surface.   The fluid device according to claim 5 or 6, wherein the bonding layer and the fluid device main body have an equivalent linear expansion coefficient.   The fluid device according to claim 5, wherein the fluid device is a piezoelectric pump.

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