JP2007162760A - Microvalve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microvalve which enables the inexpensive and highly precise flow control. <P>SOLUTION: A valve body forming substrate 20 comprises: a first diaphragm 22 to form an inlet port secondary side space 41 continuing to a frame 21 and communicating with an inlet port 11 between a valve seat substrate 10; and a second diaphragm 23 to form an inlet port primary side space 42 continuing to the frame 21, having a valve body 24 formed integrally and continuously, and communicating with an outlet port 12 between the valve seat substrate 10 in the frame 21. The first diaphragm 22 doubles as a movable electrode 28 for flow detection, and a movable electrode 25 for driving is formed in the valve body 24. A fixed electrode forming substrate 30 is secured to the valve body forming substrate 20 in such a state that a standard pressure space 52 enabling the displacement of the first diaphragm 22 is formed together with a valve body displacement space 55 between the valve body forming substrate 20 and it. The fixed electrode 32 for flow detection is formed to oppose the movable electrode 28 for the flow detection. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a microvalve that controls the flow of fluid.

  Conventionally, a microvalve that uses a structure formed by processing a semiconductor substrate such as a silicon substrate with micromachining technology as a device that controls the flow of a small amount of fluid in the field of microelectronics or medical electronics. Have been researched and developed in various places. For example, an integrated electrostatic actuator that drives a valve body formed in a structure using electrostatic attraction has been proposed (see Patent Document 1). ).

  For example, as shown in FIG. 6, this type of microvalve includes a valve seat substrate 10 ′ having a fluid inlet 11 ′ and an outlet 12 ′ penetrating in the thickness direction, and one surface of the valve seat substrate 10 ′. A frame portion 21 ′ fixed to the side and a valve body portion 24 ′ that is disposed inside the frame portion 21 ′ and opens and closes the outlet 12 ′. The valve body portion 24 ′ is opposite to the valve seat substrate 10 ′. Forming a valve body part displacement space 55 ′ that enables displacement of the valve body part 24 ′ between the valve body forming board 20 ′ on which the driving movable electrode 25 ′ is formed and the valve body forming board 20 ′. And a fixed electrode forming substrate 30 ′ on which a driving fixed electrode 35 ′ is formed opposite to the valve seat substrate 10 ′ and opposed to the driving movable electrode 25 ′. Further, the valve body forming substrate 20 ′ has an inlet secondary side space 41 ′ which is continuous with the frame portion 21 ′ and communicates with the inlet 11 ′ between the frame portion 21 ′ and the valve seat substrate 10 ′. Outlet primary side that is continuous with the first diaphragm portion 22 ′ and the frame portion 21 ′ to be formed, and that the valve body portion 24 ′ is continuously provided integrally and communicates with the outlet seat 12 ′ between the valve seat substrate 10 ′. A second diaphragm portion 23 ′ that forms a space 42 ′ is disposed.

  The microvalve having the configuration shown in FIG. 6 described above includes a pad P1 ′ electrically connected to the drive movable electrode 25 ′ and a pad (not shown) electrically connected to the drive fixed electrode 35 ′. The valve body portion 24 ′ is displaced in a direction to open the outlet 12 ′ by an electrostatic force generated between the driving movable electrode 25 ′ and the driving fixed electrode 35 ′ when a voltage is applied between them. It has become. That is, in the state where no voltage is applied between the driving movable electrode 25 ′ and the driving fixed electrode 35 ′, the above-described microvalve has the outlet 12 ′ by the valve body portion 24 ′ as shown in FIG. Is closed. On the other hand, when a voltage higher than a specified voltage is applied between the driving movable electrode 25 ′ and the driving fixed electrode 35 ′ from the driving voltage source, the valve body 24 ′ is displaced in a direction away from the outlet 12 ′. Then, the outlet 12 ′ is opened, and the fluid introduced into the space between the first diaphragm portion 22 ′ and the valve seat substrate 10 ′ through the inlet 11 ′ flows out through the outlet 12 ′. Become.

In the microvalve described above, a voltage pulse is periodically applied from the driving voltage source between the driving movable electrode 25 ′ and the driving fixed electrode 35 ′, and the duty ratio (voltage pulse for one cycle time) is applied. By controlling the pulse width ratio) by the control circuit, the flow rate of the fluid can be controlled to an arbitrary flow rate.
JP 2004-176802 A

  However, in the microvalve having the configuration shown in FIG. 6, in order to control the above-described duty ratio, a flow rate sensor for detecting the flow rate of the fluid is provided separately from the microvalve, and the output of the flow rate sensor is controlled by the control circuit. Without accurate feedback, accurate flow control could not be achieved. In short, in order to perform highly accurate flow control using the above-described microvalve, it is necessary to prepare a separate flow sensor, which increases costs.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide a microvalve that enables highly accurate flow rate control at low cost.

  According to the first aspect of the present invention, there is provided a valve seat substrate in which a fluid inlet and outlet are provided in a thickness direction, a frame portion formed using a semiconductor substrate, and fixed to one surface side of the valve seat substrate. Between the valve body forming substrate and a valve body forming substrate having a valve body portion that is disposed inside the valve portion and that has a valve body portion that opens and closes the outflow port, and on which the movable electrode for driving is formed on the opposite side of the valve seat substrate in the valve body portion A fixed electrode formation in which a fixed electrode for driving is formed which is fixed to the opposite side of the valve seat substrate and forms a valve element displacement space that enables displacement of the valve element portion and is opposed to the movable electrode for driving. A first diaphragm portion and a frame that form an inlet secondary side space that is continuous with the frame portion and communicates with the inlet between the valve seat substrate and the valve body forming substrate. And the valve body part is provided continuously and integrally with the valve seat. A second diaphragm portion that forms an outlet primary side space communicating with the outlet between the plate and a flow rate detecting movable electrode is formed in the first diaphragm portion; A reference pressure space that enables displacement of the first diaphragm portion is formed between the body forming substrate and the valve body forming substrate, and is opposed to the flow detection movable electrode. A fixed electrode for detecting the flow rate is formed.

  According to this invention, the first diaphragm is displaced according to the pressure difference between the pressure on the secondary side of the inlet and the pressure in the reference pressure space, and the distance between the flow rate detecting movable electrode and the flow rate detecting fixed electrode. Since the capacitance of the capacitor including the movable electrode for detecting the flow rate and the fixed electrode for detecting the flow rate changes, for example, if the pressure in the reference pressure space is made equal to the pressure on the secondary side of the outlet, a separate flow sensor It is possible to detect the flow rate of the fluid with high accuracy without preparing the sensor, and the movable electrode for detecting the flow rate can be formed simultaneously with the movable electrode for driving, and the fixed electrode for detecting the flow rate can be used for driving. Since it can be formed at the same time as the fixed electrode, it is easy to manufacture and the cost can be reduced.

  The invention of claim 2 is characterized in that, in the invention of claim 1, the pressure in the reference pressure space is set equal to the pressure on the secondary side of the outlet.

  According to this invention, when the pressure on the secondary side of the outlet is used as constant, the reference pressure space is provided without providing a structure for communicating the reference pressure space with the secondary side of the outlet. Can be made substantially equal to the pressure on the secondary side of the outlet, so that the size can be reduced and the manufacture is facilitated as compared with the case where the structure is provided.

  According to a third aspect of the present invention, in the first aspect of the invention, a pressure introduction port communicating with the reference pressure space is provided in the thickness direction in the fixed electrode forming substrate, and a pressure on a secondary side of the outflow port is set as the reference pressure. A pressure transmission path is provided which transmits the pressure to the pressure space and equalizes the pressure in the reference pressure space and the pressure on the secondary side of the outlet.

  According to this invention, even when the pressure on the secondary side of the outlet is not constant and varies, the pressure in the reference pressure space can be made substantially equal to the pressure on the secondary side of the outlet, It becomes possible to detect the flow rate of the fluid with high accuracy.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, in the valve seat substrate, a pressure introduction port constituting a part of a path for transmitting the pressure of the outflow port to the reference pressure space is provided in the thickness direction. The connecting pipe for connecting the fluid discharge pipe is fixed in a manner straddling the outlet and the pressure inlet on the side opposite to the valve body forming board side, and the valve body forming board is connected to the pressure inlet. And a pressure introduction through hole that communicates with the reference pressure space in the thickness direction.

  According to this invention, even when the pressure on the secondary side of the outlet is not constant and varies, the pressure in the reference pressure space can be made substantially equal to the pressure on the secondary side of the outlet, It becomes possible to detect the flow rate of the fluid with high accuracy.

  According to the first aspect of the present invention, there is an effect that it is possible to control the flow rate with high accuracy at low cost.

(Embodiment 1)
Hereinafter, the microvalve of the present embodiment will be described with reference to FIGS. 1 and 2. The microvalve of this embodiment can be used by being provided on a supply path for liquid fuel (for example, methanol, pure water, aqueous methanol solution, etc.) to a small fuel cell or fuel reformer, for example. It can be used for other purposes. In the microvalve of the present embodiment, an inlet 11 and an outlet (valve) 12 of a fluid (for example, liquid fuel) are provided in the thickness direction and flow on one surface (upper surface in FIG. 1A). A valve seat base plate 10 having a valve seat 13 protruding from the periphery of the outlet 12, a frame portion 21 fixed to the one surface side of the valve seat base plate 10, and an inner side of the frame portion 21 that opens and closes the outlet 12. Between the valve body forming substrate 20 and the valve body forming substrate 20 in which the movable electrode 25 for driving is formed on the side opposite to the valve seat substrate 10 side in the valve body portion 24. A fixed body in which a fixed electrode for driving 35 is formed which is fixed to the opposite side of the valve seat substrate 10 and forms a valve body part displacement space 55 that allows the displacement of the part 24 and is opposed to the movable electrode 25 for driving. And an electrode forming substrate 30.

  Here, the valve body forming substrate 20 forms a first inlet side space 41 that is continuous with the frame portion 21 and communicates with the inlet port 11 between the frame portion 21 and the valve seat substrate 10. A second diaphragm portion that is continuous with the diaphragm portion 22 and the frame portion 21 and that has a valve body portion 24 provided continuously and integrally, and forms an outlet primary side space 42 that communicates with the outlet port 12 between the valve seat substrate 10. 23 is arranged.

  In the microvalve of this embodiment, the valve body forming substrate 20 is formed using a semiconductor substrate (in this embodiment, a p-type silicon substrate having a low impurity concentration), and the valve seat substrate 10 is Pyrex (registered). The fixed electrode forming substrate 30 is formed using the second glass substrate made of Pyrex (registered trademark), and the valve body forming substrate 20 and the valve seat substrate are formed using the first glass substrate made of the trademark). 10 is fixed by anodic bonding, and the valve body forming substrate 20 and the fixed electrode forming substrate 30 are fixed by anodic bonding.

  Here, the driving movable electrode 25 formed on the valve body forming substrate 20 is constituted by a high concentration impurity diffusion layer (for example, an impurity diffusion layer in which boron is diffused at a high concentration), and is formed on the fixed electrode formation substrate 30. The driving fixed electrode 35 is made of a metal film (for example, a laminated film of a platinum film and a chromium thin film). The material of the metal film constituting the driving fixed electrode 35 is not limited to platinum or chromium, and for example, aluminum, nickel, titanium, tungsten, gold, or the like may be employed.

  Here, the driving movable electrode 25 and the driving fixed electrode 35 are electrically connected to the pads P1 and P2 formed on the fixed electrode forming substrate 30 through the metal wirings 36 and 38. Therefore, when a voltage is applied between the pad P1 electrically connected to the drive movable electrode 25 and the pad P2 electrically connected to the drive fixed electrode 35, the drive movable electrode 25 and the drive fixed The valve body portion 24 is displaced in a direction to open the outlet 12 by an electrostatic force generated between the electrode 35 and the electrode 35. That is, the basic operation principle of the microvalve of the present embodiment is the same as that of the conventional example shown in FIG. 6, and in a state where no voltage is applied between the driving movable electrode 25 and the driving fixed electrode 35. The outlet 12 is closed by the valve body 24 as shown in FIG. On the other hand, when a voltage higher than the specified voltage is applied between the driving movable electrode 25 and the driving fixed electrode 35 from the driving voltage source, the valve body 24 is displaced in a direction away from the outlet 12, as shown in FIG. The outlet 12 is opened as in (b). In short, the microvalve of the present embodiment constitutes a normally closed type microvalve. It should be noted that the drive movable electrode 25 and the drive fixed electrode 35 are prohibited from contacting the drive movable electrode 25 and the drive fixed electrode 35 on the drive movable electrode 25 in the valve body forming substrate 20. A stopper 29 made of an insulating film to be prevented is provided.

  Further, in the microvalve of the present embodiment, the outlet primary side space between the valve seat substrate 10 and the second diaphragm portion 23 through the inlet 11 in a state where the outlet 12 is closed by the valve body 24. In order to prevent the valve body 24 from being lifted by the pressure of the fluid that has flowed into the valve 42 and opening the outlet 12, for example, a gas such as an inert gas or air is predetermined in the valve body displacement space 55. It is sealed with pressure. Here, in the microvalve of this embodiment, the reference pressure space 52 that enables the displacement of the first diaphragm portion 22 between the fixed electrode forming substrate 30 and the valve body forming substrate 20 is formed together with the valve body portion displacement space 55. The valve body forming substrate 20 is fixed to the valve body forming substrate 20, and the valve body portion displacement space 55 and the reference pressure space 52 communicate with each other.

  Therefore, in the microvalve of the present embodiment, the inlet 11 is in a state where no voltage is applied between the driving movable electrode 25 and the driving fixed electrode 35 (that is, the valve body portion 24 is not displaced). The first diaphragm portion 22 bends by receiving the pressure of the fluid flowing into the inlet secondary space 41 between the valve seat substrate 10 and the first diaphragm portion 22 (toward the fixed electrode forming substrate 30 side). By deforming in a convex shape, a closing force that is a force in a direction in which the valve body portion 24 closes the outlet 12 acts.

  Hereinafter, each of the valve seat substrate 10, the valve body forming substrate 20, and the fixed electrode forming substrate 30 will be described in detail.

  The outer peripheral shape of the valve seat substrate 10 is a rectangular shape, and a channel recess 15 serving as a fluid channel between the inlet 11 and the outlet 12 is formed on the one surface of the valve seat substrate 10. The inlet secondary side space 41 and the outlet primary side space 42 communicate with each other. Here, the opening shape of the inflow port 11 and the outflow port 12 is circular, and the inner peripheral shape of the recess 15 for flow paths is rectangular. The valve seat 13 is continuously and integrally formed on the periphery of the outlet 12 in the valve seat substrate 10 so as to protrude from the inner bottom surface of the flow path recess 15. Is a metal thin film (for example, a chromium thin film) that prevents the valve body portion 24 and the valve seat 13 from being bonded when the frame portion 21 of the valve body forming substrate 20 and the valve seat substrate 10 are fixed together by anodic bonding. ) Is formed.

  The outer peripheral shape of the valve body forming substrate 20 is a rectangular shape having the same outer size as the valve seat substrate 10. The valve body forming substrate 20 is formed by processing the above-described semiconductor substrate using a micromachining technique. Specifically, the valve body forming board 20 uses a lithography technique, an etching technique, etc. It is supported by the frame portion 21 via the diaphragm portion 23. Here, the valve body 24 is formed in a shape in which the cross-sectional area gradually decreases as the valve seat 13 is approached.

  Further, the valve body forming substrate 20 has a high-concentration impurity diffusion layer (for example, an impurity diffusion layer in which boron is diffused at a high concentration) 204 formed on one surface side opposite to the valve seat substrate 10 side. Of the impurity diffusion layer 204, a portion formed in the valve body portion 24 constitutes the drive movable electrode 25, and a portion formed over the entire first diaphragm portion 22 constitutes the flow rate detection movable electrode 28. (The first diaphragm portion 22 also serves as the flow rate detection movable electrode 28). Accordingly, the drive movable electrode 25 and the flow rate detection movable electrode 28 are formed at the same time and have the same potential. Here, the drive movable electrode 25 and the flow rate detection movable electrode 28 are electrically connected to the pad P <b> 1 through the above-described metal wiring 36 formed on the fixed electrode forming substrate 30. The diaphragm portions 22 and 23 are formed in a corrugated plate shape, and a plurality of annular concave grooves 22 a and 23 a are concentrically formed on the side facing the fixed electrode forming substrate 30. In the present embodiment, the diaphragm portions 22, 23 are corrugated plate-like, so that the diaphragm portions 22, 23 bend with a smaller pressure than when the diaphragm portions 22, 23 are each flat. Although it is made easy, even if it is flat, it can be made easy to bend similarly by optimizing the design.

  Although the outer peripheral shape of the fixed electrode forming substrate 30 is formed in a rectangular shape, the metal wiring 37 is attached to each of the pads P1 and P2 and the flow rate detecting fixed electrode 32 described later in a state of being fixed to the valve body forming substrate 20. The dimension of the long side (the dimension in the left-right direction in FIG. 2A) is the dimension of the long side of the valve body forming substrate 20 (FIG. 2B) so that the pad P3 electrically connected via It is set longer than the dimension in the left-right direction.

  Here, the fixed electrode forming substrate 30 has a first space forming recess 30a for forming the above-described reference pressure space 52 on the surface facing the valve body forming substrate 20, and the above-described valve body portion displacement space 55. The second space forming recess 30b is formed, the flow rate detecting fixed electrode 32 is formed on the inner bottom surface of the first space forming recess 30a, and the second space forming recess is formed. A driving fixed electrode 35 is formed on the surface of the portion protruding from the inner bottom surface of 30b. Therefore, in a state where the fixed electrode forming substrate 30 is fixed to the valve body forming substrate 20, the flow rate detecting fixed electrode 32 faces the flow rate detecting movable electrode 28, and the driving fixed electrode 35 becomes the driving movable electrode 25. It comes to oppose. Here, the fixed electrode for flow rate detection 32 and the fixed electrode for driving 35 employ the same metal material and have the same film thickness, and are formed at the same time. Each space forming recess 30a, 30b is opened in a circular shape, and the flow rate detecting fixed electrode 32 and the driving fixed electrode 35 are formed in a circular shape.

  Further, on the surface of the fixed electrode forming substrate 30 facing the valve element forming substrate 20, in addition to the space forming recesses 30 a and 30 b, a communication recess 30 c for communicating both the space forming recesses 30 a and 30 b, The metal wiring 38 connected to the driving fixed electrode 35 and the metal wiring 37 connected to the flow rate detecting fixed electrode 32, which are grooves continuously formed in the second space forming recess 30b, are provided on the inner bottom surface. A wiring forming groove 30d is formed, and the air passage formed by the wiring forming groove 39d in a state where the valve body forming substrate 20 and the fixed electrode forming substrate 30 are fixed is made of resin (for example, silicone resin, epoxy It is sealed by a sealing portion (not shown) made of resin or the like. Therefore, the reference pressure space 52 and the valve body displacement space 55 described above have the same pressure.

In the microvalve of this embodiment, the flow rate of the fluid flowing through the outlet 12 with the outlet 12 open is Q, the pressure on the primary side (inlet side) of the outlet 12 is Pin, and the secondary of the outlet 12 is secondary. Assuming that the pressure on the side (outlet side) is Pout, the relationship between the pressure difference before and after the outlet 12 and the flow rate is expressed by the following equation 1, where _CV is a proportionality constant determined by the flow path structure of the microvalve. The

  Further, the area of the flow rate detection movable electrode 28 constituted by the entire first diaphragm portion 22 is S, the rigidity of the flow rate detection movable electrode 28 is k, and the displacement amount of the flow rate detection movable electrode 28 due to the fluid pressure is x. Assuming that the pressure in the reference pressure space 52 is constant at Pb, the relationship between the pressure applied to the flow rate detecting movable electrode 28 and the rigidity is expressed by the following equation (2).

  In addition, an initial gap between the flow rate detection movable electrode 28 and the flow rate detection fixed electrode 32 (a gap when no fluid is introduced into the inlet secondary space 41 through the inlet 11) is defined as d, The displacement amount of the flow rate detection movable electrode 28 due to pressure is x, the dielectric constant of the medium in the reference pressure space 52 is ε, and the capacitance of the capacitor formed by the flow rate detection movable electrode 28 and the flow rate detection fixed electrode 32. If C is C, the capacitance C is expressed by the following equation (3).

  From the above formulas 1 to 3, the flow rate Q can be expressed by the following formula 4.

  As can be seen from Equation 4, the flow rate of the fluid Q can be obtained using the capacitance C of the capacitor.

  The above formulas 2 and 4 are mathematical expressions when the pressure in the reference pressure space 52 is assumed to be Pb. However, the microvalve of the present embodiment uses the pressure on the secondary side of the outlet 12 as a constant. Yes, since the pressure in the reference pressure space 52 is set to a pressure equal to the pressure Pout on the secondary side of the outlet 12, the relationship between the pressure applied to the flow rate detecting movable electrode 28 and the rigidity is expressed by the following equation (5). The

  From the above formulas 1, 3, and 5, the flow rate Q can be expressed by the following formula 6.

  Thus, the microvalve of the present embodiment uses the pressure on the secondary side of the outlet 12 as constant, and the pressure in the reference pressure space 52 is set to the same pressure as the pressure on the secondary side of the outlet 12. The first diaphragm portion 22 is displaced according to the pressure difference between the pressure on the secondary side of the inlet 11 (pressure on the inlet secondary space 41) and the pressure on the reference pressure space 52. Since the distance between the detection movable electrode 28 and the flow rate detection fixed electrode 32 changes and the capacitance C of the capacitor including the flow rate detection movable electrode 28 and the flow rate detection fixed electrode 32 changes, a separate flow rate sensor is prepared. In addition, the fluid flow rate Q can be detected with high accuracy, and the flow rate detection movable electrode 28 can be formed simultaneously with the drive movable electrode 25 and the flow rate detection fixed electrode 32 can be formed. For driving Since it is possible to electrode 35 formed simultaneously, thereby the easy manufacturing cost. In this embodiment, the pressure on the secondary side of the outlet 12 is used as constant, and the pressure in the reference pressure space 52 is set to a pressure equal to the pressure Pout on the secondary side of the outlet 12. However, if the pressure Pb in the reference pressure space 52 is constant, the flow rate Q can be obtained from the above equation 4.

  Further, in the microvalve of the present embodiment, since the pressure in the reference pressure space 52 is set to the pressure on the secondary side of the outlet 12, the reference pressure space 52 and the secondary side of the outlet 12 are communicated. There is no need to provide this structure, and it is possible to reduce the size and facilitate the manufacture as compared with the case where the structure is provided.

(Embodiment 2)
The basic configuration of the microvalve of the present embodiment is substantially the same as that of the first embodiment, and as shown in FIG. 3, a pressure introduction port 33 communicating with the reference pressure space 52 penetrates through the fixed electrode forming substrate 30 in the thickness direction. And a pressure transmission path that transmits the pressure on the secondary side of the outlet 12 to the reference pressure space 52 to equalize the pressure in the reference pressure space 52 and the pressure on the secondary side of the outlet 12. The point is different. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted. Here, the arrows in FIG. 3 indicate the direction of fluid flow.

  In the microvalve of the present embodiment, a connection pipe 81 for connecting a fluid supply pipe 91 is fixed to the peripheral portion of the inlet 11 on the side opposite to the valve body forming substrate 20 side of the valve seat substrate 10. A connecting pipe 82 for connecting a fluid discharge pipe 92 is fixed to the periphery of the pipe 12. In addition, a connecting pipe 83 for connecting a pressure distribution pipe 93 branched from the pipe 92 is fixed to the peripheral portion of the pressure introduction port 33 on the opposite side of the fixed electrode forming board 30 to the valve body forming board 20 side. In the present embodiment, the pressure distribution pipe 93 and the connection pipe 83 constitute a pressure transmission path.

  Thus, in the microvalve of the present embodiment, even when the pressure on the secondary side of the outlet 12 is not constant and varies, the pressure in the reference pressure space 52 is substantially equal to the pressure on the secondary side of the outlet 12. Therefore, the flow rate of the fluid can be detected with high accuracy.

(Embodiment 3)
The basic configuration of the microvalve of the present embodiment is substantially the same as that of the first embodiment, and there is a difference between the valve seat substrate 10 and the valve body forming substrate 20 as shown in FIGS. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  In the present embodiment, the valve seat substrate 10 is provided with a pressure introduction port 16 that is part of a path for transmitting the pressure of the outlet 12 to the reference pressure space 52 in the thickness direction, and is opposite to the valve body forming substrate 20 side. On the side, a connecting pipe 81 for connecting a fluid supply pipe 91 (see FIG. 3 described in the second embodiment) to the periphery of the inlet 11 is fixed, and a fluid discharge pipe 92 (in the second embodiment) A connecting pipe 82 for connecting the air outlet 12 and the pressure inlet 16 is fixed to the connecting pipe 82 connecting the outlet 12 and the pressure inlet 16 (see FIG. 3).

  Further, the valve body forming substrate 20 in the present embodiment is provided with a pressure introducing through-hole 26 that allows the pressure introducing port 16 and the reference pressure space 52 to communicate with each other in the thickness direction.

  Thus, in the microvalve of the present embodiment, even when the pressure on the secondary side of the outlet 12 is not constant and varies, the pressure in the reference pressure space 52 is substantially equal to the pressure on the secondary side of the outlet 12. Therefore, the flow rate of the fluid can be detected with high accuracy. Further, since it is not necessary to branch the pressure distribution pipe 93 from the pipe 92 as in the second embodiment, the size can be reduced as compared with the second embodiment.

Embodiment 1 is shown, (a) is a schematic sectional view, (b) is an operation explanatory diagram. 4A is a schematic bottom view of a fixed electrode forming substrate, FIG. 4B is a schematic plan view of a valve body forming substrate, and FIG. 4C is a schematic plan view of a valve seat substrate. FIG. 6 is a schematic cross-sectional view showing a second embodiment. FIG. 6 is a schematic cross-sectional view showing a third embodiment. 4A is a schematic bottom view of a fixed electrode forming substrate, FIG. 4B is a schematic plan view of a valve body forming substrate, and FIG. 4C is a schematic plan view of a valve seat substrate. It is a schematic sectional drawing which shows a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Valve seat board | substrate 11 Inflow port 12 Outflow port 13 Valve seat 15 Recess for flow path 20 Valve body formation board 21 Frame part 22 1st diaphragm part 23 2nd diaphragm part 24 Valve body part 25 Drive movable electrode 28 Flow detection Movable electrode 30 fixed electrode forming substrate 32 fixed flow detection electrode 35 fixed electrode for driving 41 inlet side secondary space 42 outlet primary side space 52 reference pressure space 55 valve body part displacement space

Claims (4)

  A valve seat substrate having fluid inlets and outlets penetrating in the thickness direction, a frame portion formed using a semiconductor substrate and fixed to one surface side of the valve seat substrate, and a flow disposed inside the frame portion Displacement of the valve body portion between the valve body forming substrate having a valve body portion for opening and closing the outlet and having a movable electrode for driving formed on the side opposite to the valve seat substrate in the valve body portion. A fixed electrode forming substrate that is fixed to the opposite side of the valve seat substrate in a form that forms a valve body displacement space that enables the fixed electrode forming substrate on which a driving fixed electrode facing the movable electrode for driving is formed. The forming substrate is continuous with the first diaphragm portion and the frame portion forming the inlet secondary side space that is continuous with the frame portion and communicates with the inlet between the frame portion and the valve seat substrate. Outlet between the body part and the valve seat board A second diaphragm portion that forms a communicating outlet primary side space is disposed, a flow rate detecting movable electrode is formed on the first diaphragm portion, and the fixed electrode forming substrate is disposed between the fixed electrode forming substrate and the valve element forming substrate. A fixed pressure electrode for detecting a flow rate is formed which is fixed to a valve body forming substrate and forms a reference pressure space enabling displacement of the diaphragm portion together with the displacement space for the valve body portion, and is opposed to the movable electrode for detecting the flow rate. A microvalve characterized by being made.   The microvalve according to claim 1, wherein the pressure in the reference pressure space is set to a pressure equal to the pressure on the secondary side of the outlet.   A pressure introduction port that communicates with the reference pressure space is provided in the fixed electrode forming substrate in the thickness direction, and a pressure on the secondary side of the outlet is transmitted to the reference pressure space, and the pressure in the reference pressure space and the pressure 2. The microvalve according to claim 1, further comprising a pressure transmission path that equalizes the pressure on the secondary side of the outlet.   In the valve seat substrate, a pressure introduction port that constitutes a part of a path that transmits the pressure of the outlet port to the reference pressure space is provided in a thickness direction, and a connection pipe that connects a fluid discharge pipe includes: A pressure-introducing through-hole that communicates between the pressure-inlet opening and the reference pressure space, which is fixed on the side opposite to the valve-body-forming substrate side so as to straddle the outlet and the pressure inlet. The microvalve according to claim 1, wherein the microvalve is penetrated in the thickness direction.

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