JP5585178B2 - Fluid control device - Google Patents

Description

  The present invention relates to a fluid control device, and more particularly to a fluid control device that can be used in a fuel injection device for a diesel vehicle.

  In recent years, a common rail device (common rail system) has come to be used as a fuel supply device (fuel injection device) for a diesel automobile, which is a compression ignition internal combustion engine.

  Common rail devices are: 1. Super high pressure fuel can be injected. For reasons such as easy control of the fuel injection amount, it is possible to atomize the fuel, promote mixing of the fuel and air, and reduce black smoke and PM (fine particles). Further, the common rail device can reduce the combustion temperature and NOx (nitrogen oxide) by changing the fuel injection amount and timing.

  In the current common rail device, an electromagnetic valve having a solenoid is used to move a needle that opens and closes a hole for injecting fuel. Further, as a common rail device, there is a device that moves a needle by a piezo actuator using a piezo element (piezoelectric element) as a more responsive device.

  In many cases, the drive of a needle by a solenoid applies a hydraulic pressure to the needle so as to move the needle in response to energization of the solenoid. Further, the driving of the needle by the piezo element is a mechanism that employs the direct driving of the needle by the piezo element as disclosed in Patent Document 1.

JP 2006-316777 A JP 2008-215186 A JP 2006-101691 A

  First, problems with needle drive by solenoids are listed.

  In driving the needle by a solenoid, the hydraulic pressure and the amount of oil flowing into the control chamber are adjusted by moving the solenoid up and down. For this reason, it can be said that stepwise needle control (indirect drive) is performed as solenoid → control room → needle, but the possibility of poor response cannot be denied. In addition, since the needle is driven via hydraulic pressure, it is considered that the damping motion is generated.

  Next, the problem of needle driving by a piezo element will be listed.

  Since the indirect drive is not performed unlike the solenoid, there is no problem like the needle drive by the solenoid, but the following event occurs because the piezo element is used.

  First, as taken up in [Problems to be Solved by the Invention] in Patent Document 2, there are variations between individual piezo stacks in which piezo elements are stacked, and deterioration over time. Further, in [Background Art] of [Detailed Description of the Invention] in Patent Document 3, since the piezo stack is arranged in a layered manner with the piezo elements stacked, when a control voltage is applied to the piezo stack, It is said that a tensile stress is generated and a crack is generated.

  It is described in [Background Art] (paragraph 0004) of Patent Document 3 that such a problem occurs because the piezo elements are stacked in a “layered state”.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a device that controls a fluid at a higher speed and with a higher response using a piezoelectric element, and also provides a fluid control device that reduces the risk of the piezoelectric element being damaged by stress. There is.

In order to achieve the above object, the present invention provides a pipe through which a fluid flows , a plug that closes a hole formed in the middle of the pipe from the upstream side, a first piezoelectric element that extends by application of a voltage, and the first A first fixing member that fixes one end of one piezoelectric element and is supported by the tube, a linear first tension member that connects the other end of the first piezoelectric element and the plug, and the first fixing A first insertion hole formed through the material and the first piezoelectric element to allow the first tension material and fluid to pass therethrough, and opposed to the plug on the opposite side of the first piezoelectric element. A second piezoelectric element that is elongated by application of a voltage; a second fixing member that fixes one end of the second piezoelectric element and is supported by the tube; and the other end of the second piezoelectric element and the plug. A linear second tension member to be connected, and the second fixing member and the second piezoelectric element are penetrated. Is provided with a second insertion hole for passing said second tension member and the fluid, Rutotomoni is extended the first piezoelectric element by applying a voltage to the first piezoelectric element, said second piezoelectric element The second piezoelectric element is degenerated by releasing the voltage application to the first piezoelectric element, the plug is opened by pulling the first tension member by the first piezoelectric element, and the voltage application to the first piezoelectric element is performed. The first piezoelectric element is degenerated by releasing, the second piezoelectric element is extended by applying a voltage to the second piezoelectric element, and the second tension member is pulled by the second piezoelectric element. The stopper is closed .

Here, the first and second piezoelectric elements may be made of a single crystal.

The stopper may be a third piezoelectric element.

It may also cover some or all of the pre-hexene with a protective material.

  Further, a buffer material may be sandwiched between the stopper and the protective material.

  According to the present invention, it is possible to provide a device that controls a fluid at a higher speed and with a higher response using a piezoelectric element, and to provide a fluid control device that reduces the risk of the piezoelectric element being damaged by stress. There is an excellent effect of being able to.

1 is a schematic perspective view of a fluid control device according to an embodiment of the present invention. It is a sectional side view of the fluid control apparatus which concerns on one Embodiment of this invention, (a) shows a "capped" state, (b) shows a "capped" state. It is a perspective view which shows the modification of the connection of a tension | tensile_strength material and a piezoelectric element. It is a perspective view which shows the modification of the structure of a piezoelectric element. It is a sectional side view of the fluid control apparatus which concerns on other embodiment, (a) shows a "capped" state, (b) shows a "capped" state. It is a sectional side view which shows the modification of a stopper. It is a schematic perspective view which shows the structure of the fluid control valve which consists of a fluid control apparatus. It is a schematic perspective view which shows the structure of the fluid control valve which consists of a fluid control apparatus. FIG. 9 is a side cross-sectional view of the fluid control valve shown in FIG. 8, where (a) shows an “open” state and (b) shows a “closed” state.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  The fluid control device 10 according to the present embodiment is used in, for example, a common rail fuel injection device of a diesel engine mounted on a vehicle.

  As shown in FIGS. 1 and 2, the fluid control apparatus 10 according to the present embodiment includes a plug (valve element) 13 that closes a hole 12 formed in the middle of a flow path 11 through which fluid flows from the upstream side, and a voltage. The piezoelectric element 14 that is expanded by the application of, a fixing member 15 that fixes one end (lower end in the illustrated example) of the piezoelectric element 14, the other end (upper end in the illustrated example) of the piezoelectric element 14, and the plug 13. This is a mechanism provided with a tension member 16 that connects (in the illustrated example, the upper end of the stopper 13) as a minimum component. In FIG. 2, reference numeral 17 denotes an electric circuit for applying a voltage to the piezoelectric element 14.

  The flow path 11 is connected to a common rail (pressure accumulator) and formed, for example, inside a casing (not shown) to which the fixing material 15 is attached. A hole 12 is provided in the middle of the flow path 11, and the hole 12 has a tapered sheet surface 18 that is reduced in diameter from the upstream side toward the downstream side.

  The stopper 13 of this embodiment is formed in an inverted frustoconical shape. That is, when the portion (upper end) to which the tension member 16 is attached is the base end side of the plug 13, the plug 13 is shaped so that the width (outer diameter) decreases toward the distal end side. When the hole 12 is closed by the plug 13, the outer peripheral surface of the plug 13 is in close contact (contact) with the sheet surface 18 of the hole 12. The stopper 13 is made of, for example, a metal material (for example, iron, aluminum, etc.).

  The piezoelectric element 14 of the present embodiment is a piezo element. The piezoelectric element 14 is extended by turning on the electric circuit 17 and applying a voltage to the piezoelectric element 14, and the piezoelectric element 14 is degenerated by turning off the electric circuit 17 and releasing the applied voltage to the piezoelectric element 14. It has become. In the piezoelectric element 14, in order to attach the tension member 16 to the upper end portion of the piezoelectric element 14, an insertion hole 19 through which the tension member 16 passes is formed through the upper surface and the lower surface of the piezoelectric element 14. The piezoelectric element (piezo element) 14 of this embodiment is made of a single crystal and is formed in a truncated cone shape.

  The tension member 16 of the present embodiment is formed in a linear shape. In the present embodiment, the disk-shaped connecting material 20 is fixed to the upper surface of the piezoelectric element 14, and the upper end portion of the tension material 16 is fixed to the lower surface of the connecting material 20. The tension member 16 is made of, for example, a metal material (for example, iron, aluminum, etc.).

  The fixing member 15 of the present embodiment has a pair of fixing plates 21 formed in a square plate shape. In the present embodiment, one fixed plate 21 is disposed apart from the other fixed plate 21 in a direction perpendicular to the expansion / contraction direction of the piezoelectric element 14 (in the illustrated example, the left-right direction). The tension member 16 that connects the piezoelectric element 14 and the plug 13 is passed through the gap 22. The piezoelectric element 14 can be displaced upward from the fixed plate 21 by fixing the lower end portion of the piezoelectric element 14 to the upper surface of each fixed plate 21, turning on the electric circuit 17 and applying a voltage to the piezoelectric element 14. It becomes possible. The fixed plate 21 is made of, for example, a metal material (for example, iron, aluminum, etc.).

  In the present embodiment, the piezoelectric element 14 and the fixing plate 21 are disposed outside the flow path 11, and the tension member 16 is inserted through a through hole 23 that penetrates a wall portion constituting the flow path 11. The clearance between the through hole 23 and the tension member 16 is made relatively small, or a seal material (not shown) is interposed between the through hole 23 and the tension member 16, thereby allowing the flow through the through hole 23. It is preferable to minimize the amount of fluid leaking outside the passage 11.

  The operation of the fluid control apparatus 10 according to this embodiment will be described with reference to FIG.

  As shown in FIG. 2A, a plug 13 is disposed in the fluid flow path 11 and the hole 12 provided in the middle of the flow path 11 is closed with the plug 13 so that the front side ( The pressure of the fluid in the flow path 11 on the upstream side can be increased. Here, as shown in FIG. 2B, by turning on the electric circuit 17 and applying a voltage to the piezoelectric element 14, the piezoelectric element 14 is displaced upward from the fixed plate 21 (the piezoelectric element 14 is expanded). The plug 13 is opened by pulling up the tension member 16 connected to the piezoelectric element 14 upward and separating the plug 13 from the sheet surface 18 of the hole 12. That is, the plug 13 is pulled up with tension by the tension member 16 to open (open) the plug (valve element) 13. By opening the plug 13 and opening the hole 12, the fluid flows out of the flow path 11 through the hole 12 from the upstream flow path 11 where the pressure is maintained.

  Then, as shown in FIG. 2A, the electric circuit 17 is turned off to release the voltage application to the piezoelectric element 14, thereby degenerating the piezoelectric element 14. Then, since the tension member 16 is not pulled by the piezoelectric element 14, the plug 13 is pushed toward the hole 12 by the fluid flow (pressure), and the plug 13 is naturally closed. That is, the plug (valve element) 13 is closed (closed) using the flow (pressure) of the fluid.

  In addition, solid, liquid, a solid-liquid two-phase flow, a gas-liquid two-phase flow, a solid-gas two-phase flow etc. can be used for the fluid which flows through the flow path 11.

  The piezoelectric element 14 can generate vibrations from a low frequency up to about 100 MHz, and is controlled to a very small flow rate (injection amount, injection time) by shortening the opening / closing time of the hole 12 (injection hole). I can do it.

  By the way, at present, in a common rail fuel injection device of a diesel engine, fuel is pressurized to approximately 200 MPa (2000 atm) and injection is performed. Therefore, when the fluid control device 10 according to this embodiment is used in a common rail fuel injection device, a fluid pressure (fuel pressure) of about 200 MPa is also applied to the piezoelectric element 14. Further, the piezoelectric element 14 pulls up the tension member 16 against the fluid pressure (fuel pressure) of about 200 MPa. It is known that a general piezoelectric element 14 can withstand a load of at least 400 MPa under a static load, and in a repeated load, when σmin / σmax = 0.05, it is not broken at about 100 MPa. It has been. For this reason, when a voltage is applied, it is expected to show a lower value than this, but the piezoelectric element 14 as described above can be applied by improving the material itself.

  According to the present embodiment, the plug 13 that closes the hole 12 formed in the middle of the flow path 11 through which the fluid flows from the upstream side, the piezoelectric element 14 that expands when a voltage is applied, and one end of the piezoelectric element 14 are fixed. And a tension member 16 that connects the other end of the piezoelectric element 14 to the plug 13. The piezoelectric element 14 is extended by applying a voltage to the piezoelectric element 14, and the tension element 16 is expanded by the piezoelectric element 14. Since the fluid control device 10 is configured so as to open the plug 13 by pulling, the plug 13 (needle) can be directly driven by the piezoelectric element 14 or the supply of fluid (fuel) is directly controlled. It is possible to provide a device that controls the fluid at a higher speed and with a higher response by using the piezoelectric element 14.

  Further, in the present embodiment, since the piezoelectric element 14 is made of a single crystal, there is no problem of tensile stress that can occur between layers when the piezoelectric elements are stacked and arranged in layers, so that the piezoelectric element 14 is damaged by stress. Therefore, it is possible to provide the fluid control device 10 with a low risk of occurrence.

  In addition, the fluid control device 10 can be configured from the millimeter order to the nanometer order by the fine processing accuracy of the piezoelectric element 14, the tension material 16, the fixing material 15 and the stopper 13, and the production material of the tension material 16. When the fluid control device 10 is used in a common rail fuel injection device, it is possible to control the flow rate of an unprecedented fuel injection amount. Further, the device (the piezoelectric element 14, the tension member 16, the fixing member 15, and the plug 13) is miniaturized, and the fluid control device 10 is disposed at the fuel outlet, thereby controlling the fluid with higher speed and higher response. Can be provided.

  Hereinafter, the supplement of the minimum component of the fluid control apparatus 10 is mentioned and demonstrated.

[Connection between piezoelectric element and tension material]
The insertion hole 19 through which the tension member 16 provided in the piezoelectric element 14 passes may be formed at a location where the tension member 16 of the piezoelectric element 14 passes, and the tension member 16 may be attached to an intermediate portion of the piezoelectric element 14. (See FIG. 3B). In that case, the insertion hole 19 does not need to penetrate the upper surface and the lower surface of the piezoelectric element 14, and may extend from the lower surface of the piezoelectric element 14 to the intermediate portion.

  In order to connect the piezoelectric element 14 and the tension member 16, the tension member 16 may be directly attached to the piezoelectric element 14 (see FIGS. 3A and 3B), and the tension member 16 is connected to the piezoelectric element 14 and the connection member. 20 may be attached to the piezoelectric element 14 in a sandwiched manner.

  The upper end portion of the tension member 16 may be attached to the upper surface of the piezoelectric element 14 (see FIG. 3A), or the upper end portion of the tension member 16 may be embedded in the piezoelectric element 14 (see FIG. 3B). In addition, the tension member 16 is not shaped to stick to the piezoelectric element 14, and it is also conceivable to insert the tension member 16 having a shape in which the needle portion of the thumbtack is long into the insertion hole 19 from above the piezoelectric element 14. (See FIG. 3C). In these cases, the connecting member 20 for connecting the piezoelectric element 14 and the tension member 16 is not necessary.

〔Piezoelectric element〕
The piezoelectric element 14 need not be frustoconical. For example, the piezoelectric element 14 has a cylindrical shape or a columnar shape (see FIG. 4A), a rectangular parallelepiped shape or a cubic shape (see FIG. 4B), an inverted frustoconical shape (see FIG. 4C), a square frustum shape. It is conceivable to adopt a shape such as (see FIG. 4D).

  In the present invention, it is basically desirable that the piezoelectric element 14 is made of a single crystal, but the piezoelectric element 14 can also be configured in layers within a range where no stress is applied.

[Fixing material]
The presence of the fixing material 15 (fixing plate 21) is essential. In order to displace the piezoelectric element 14 downward from the fixed plate 21, the fixed plate 21 may be attached to the upper portion of the piezoelectric element 14.

[Tension material]
As long as the tension member 16 is linear, the type of constituent atoms of the material is not limited. For example, the tension member 16 may be composed of an iron wire, an aluminum wire, a fluororesin wire, an aramid fiber wire, or the like.

  Further, when the piezoelectric element 14 is processed on a nanoscale (on the order of nanometers), if a carbon nanotube is used as the tension material 16, the high tensile strength of the plug 13 resists pressure under conditions such as high pressure. It is considered suitable for performing the movement.

  Alternatively, the tension member 16 may be formed in a relatively thick bar shape, and the stopper 13 may be closed by pushing the stopper 13 with the tension member 16.

〔plug〕
As shown in FIG. 5, the plug 13 itself can be formed of a piezoelectric element. In this case, since the stopper 13 can be moved (deformed) by applying a voltage to the stopper 13, a very small amount of flow can be controlled. In this case, more complicated position control of the plug 13 can be performed by independently applying a voltage to the piezoelectric element 14 and a voltage to the plug 13 itself. Power can be supplied to the plug 13 by configuring the tension member 16 from a conductive material. In FIG. 5, reference numeral 24 indicates an electric circuit for applying a voltage to the plug 13.

  For example, the voltage is not applied to the piezoelectric element 14 by the electric circuit 17 but only the voltage is applied to the plug 13 itself by the electric circuit 24 to extend the plug 13 so that the plug 13 is in close contact with the sheet surface 18 of the hole 12. As a result, the hole 12 is blocked by the plug 13 (see FIG. 5A), the voltage applied to the plug 13 itself by the electric circuit 24 is released, the plug 13 is degenerated, and the plug 13 and the hole 12 are By creating a gap between the sheet surface 18 (see FIG. 5B), a very small amount of flow rate can be controlled.

  Further, when the plug 13 itself is formed of a piezoelectric element, there is a possibility that the plug 13 may be damaged by contact between the plug 13 and the sheet surface 18 of the hole 12. Therefore, as shown in FIG. 6, it is conceivable to cover part or all of the plug 13 with a protective material 25 that protects the outside of the plug 13. The protective material 25 is made of, for example, a metal material (for example, iron, aluminum, etc.). It is also possible to absorb the impact by inserting a buffer material 26 between the stopper 13 and the protective material 25 (see FIG. 6A).

[Others]
Although the above-mentioned thing was mentioned as the minimum component of the fluid control apparatus 10, the use of the spring material currently used for the fuel injection apparatus is also possible. For example, it is conceivable to use a spring material in order to urge the plug 13 toward the hole 12 to close it.

  Hereinafter, the structure of the fluid control valve 10A including the fluid control device 10 will be described with reference to FIGS. Components that are substantially the same as those in FIGS. 1 to 6 are denoted by the same reference numerals, and description thereof is omitted. The lower part of FIG. 7B is the same as the lower part of FIG.

  As shown in FIG. 7, the portion (hole) that can be in close contact with the stopper 13 on the minimum component for fluid control, including the piezoelectric element 14, the tension member 16, the fixing member 15, the stopper 13, and the like described above. The fluid control valve 10 </ b> A can be made by combining the 12 seat surfaces 18) and the tube 27 (in the illustrated example, a circular tube) (or a cylinder) having a portion capable of supporting the fixing material 15.

  In FIG. 7A, the piezoelectric element 14 and the fixing material 15 are disposed in the flow path 11. The fixing member 15 includes a disk-like fixing plate 28 supported by a tube 27, and an insertion hole 29 through which the tension member 16 and the fluid pass simultaneously is provided at the center thereof. Further, an insertion hole 30 through which the tension member 16 and the fluid pass simultaneously is provided at the center of the piezoelectric element 14, and the upper end portion of the tension member 16 is attached to the upper surface of the piezoelectric element 14.

  In FIG. 7A, insertion holes 30 and 29 through which the tension member 16 and the fluid pass simultaneously are provided in the central portions of the piezoelectric element 14 and the fixing plate 28, respectively, but in FIG. In addition to the tension member 16 and the insertion holes 30 and 29 through which the fluid passes provided at the center of the fixing plate 28, the piezoelectric element 14 and the fixing plate 28 are provided with fluid passage holes 31 and 32 through which the fluid passes, respectively. ing.

  The fluid control valve 10A as shown in FIG. 7 can be made from a millimeter scale to a nanoscale minute one depending on the processing method of the piezoelectric element 14, the tension member 16, and the tube 27. Conceivable.

  The fluid control valve 10A shown in FIGS. 8 and 9 uses two minimum components composed of the piezoelectric element 14, the tension member 16, the fixing member 15, and the like, and the two tension members 16 pull the one plug 13. As described above, the minimum components (the piezoelectric element 14, the tension member 16, and the fixing member 15) are disposed so as to face each other in the tube 27. That is, the opposing piezoelectric element 14A is disposed around the plug 13 in the direction opposite to the piezoelectric element 14, and one end portion (the upper end portion in the illustrated example) of the opposing piezoelectric element 14A is connected to the opposing fixing material 15A (the opposing fixing plate 28A). The other end portion (lower end portion in the illustrated example) of the opposing piezoelectric element 14A and the stopper 13 (lower end portion of the stopper 13) are connected by an opposing tension member 16A. The plug 13 itself is composed of a piezoelectric element. Further, the power supply to the plug 13 is performed by a tension member 16 made of a conductive material. In FIG. 8, reference numeral 33 denotes an electric circuit for applying a voltage to the opposing piezoelectric element 14A.

  As shown in FIG. 9, the voltage application of the upper piezoelectric element 14 in FIGS. 8 and 9 is “ON” by the two piezoelectric elements 14 and the opposing piezoelectric elements 14 </ b> A arranged in opposite directions around the plug 13. When the voltage application of the lower opposing piezoelectric element 14A is “OFF”, the plug 13 is set to “open” (see FIG. 9A), and the voltage application of the upper piezoelectric element 14 is “OFF”. When the voltage application of the opposing piezoelectric element 14A is “ON”, the plug 13 can be “closed” (see FIG. 9B). That is, the piezoelectric circuit 14 is expanded by applying a voltage to the piezoelectric element 14 by the electric circuit 17, and the opposing piezoelectric element 14A is degenerated by releasing the voltage application to the opposing piezoelectric element 14A by the electric circuit 33. The plug (valve element) 13 is opened (valve opened) by pulling the tension member 16 by the element 14 (see FIG. 9A), while the voltage application to the piezoelectric element 14 by the electric circuit 17 is released. The piezoelectric element 14 is contracted by the electric circuit 33, the voltage is applied to the counter piezoelectric element 14 </ b> A by the electric circuit 33, the counter piezoelectric element 14 </ b> A is expanded, and the counter tension member 16 </ b> A is pulled by the counter piezoelectric element 14 </ b> A to plug (valve). 13 is closed (valve closed).

  8 and 9, when the plug 13 is closed by the lower opposing piezoelectric element 14 </ b> A, the plug 13 can be pulled downward, so that the sheet surface 18 of the hole 12 that is in contact with the plug 13 is not touched. By applying force, the degree of adhesion can be increased, and fluid leakage when the plug 13 is closed can be reduced. Moreover, since the plug 13 can be opened and closed only by pulling, it is considered that the damping behavior is unlikely to occur when the plug 13 contacts the sheet surface 18 of the hole 12 or when the plug 13 is opened. Therefore, it is considered that the structure is optimal for opening and closing in a minute region. 8 and 9, since the stopper 13 itself is made of a piezoelectric element, the stopper 13 can be moved (deformed) by applying a voltage to the stopper 13 by the electric circuit 24. It becomes possible to control the flow rate. Further, by performing voltage application to the piezoelectric element 14 and the opposing piezoelectric element 14A independently from voltage application to the plug 13 itself, more complicated position control of the plug 13 can be performed.

DESCRIPTION OF SYMBOLS 10 Fluid control apparatus 11 Flow path 12 Hole 13 Plug (valve body)
14 Piezoelectric element 14A Opposing piezoelectric element 15 Fixing material 15A Opposing fixing material 16 Tension material 16A Opposing tension material 25 Protective material 26 Buffer material

Claims (5)

A pipe through which a fluid flows , a plug that closes a hole formed in the middle of the pipe from the upstream side, a first piezoelectric element that expands when a voltage is applied, and one end of the first piezoelectric element that is fixed and the pipe a first fixing member which is supported by, formed through the a first piezoelectric element and the first tension member and the other end linear connecting the said plug, said first fixing member and the first piezoelectric element A first insertion hole that allows the first tension member and fluid to pass therethrough, a second piezoelectric element that is disposed opposite to the plug on the opposite side of the first piezoelectric element, and extends by application of a voltage; A second fixing member that fixes one end of the second piezoelectric element and is supported by the tube; a linear second tension member that connects the other end of the second piezoelectric element and the plug; 2 Passing through the second tension member and the fluid formed through the second fixing member and the second piezoelectric element It includes a second insertion hole for a,
The first Rutotomoni is extended the first piezoelectric element by applying a voltage to the piezoelectric element, wherein to degenerate the second piezoelectric element by the second to release the voltage applied to the piezoelectric element, said first piezoelectric The plug is opened by pulling the first tension member by an element,
The first piezoelectric element is degenerated by releasing the voltage application to the first piezoelectric element, and the second piezoelectric element is expanded by applying a voltage to the second piezoelectric element, and the second piezoelectric element The fluid control device according to claim 1, wherein the stopper is closed by pulling the second tension member . The fluid control device according to claim 1, wherein the first and second piezoelectric elements are made of a single crystal. The fluid control device according to claim 1, wherein the stopper is made of a third piezoelectric element. The fluid control device according to claim 3 which covers a part or the whole of the pre-hexene with a protective material.   The fluid control device according to claim 4, wherein a buffer material is sandwiched between the stopper and the protective material.

Images