Fluid control valve and mass flow controller

In order to, in a short period of time, reduce to zero a measured flow rate value measured after fully closing a fluid control valve, the fluid control valve having a configuration suitable to decrease the inside volume of the fluid control valve is configured together with a valve element member, and a valve seat block provided with: an in-valve flow path that is formed inside of the valve seat block; and a valve seat surface that is brought into contact with or separated from a seating surface of the valve element member is provided with a cutout that is formed in a part of a protruded rim so as to be communicatively connected to a downstream side flow path.

TECHNICAL FIELD

The present invention relates to a fluid control valve that is a valve used for, for example, a mass flow controller for controlling a flow rate of gas, or the like, and configured to include a valve seat block and a valve element member.

BACKGROUND ART

A fluid control valve is one that intervenes between an upstream side flow path and a downstream side flow path, to control a flow rate or pressure of fluid flowing through the flow paths, or to fully close to prevent the fluid from flowing between the respective flow paths.

For example, a thermal type mass flow controller that is, sequentially from an upstream side, provided with a thermal type flow rate sensor and such a fluid control valve is used for a semiconductor manufacturing process.

In recent years, the semiconductor manufacturing process has required flow rate control performance having higher accuracy than before, and therefore the thermal type mass flow controller has been sometimes replaced by a pressure type mass flow controller that is provided with a pressure type flow rate sensor having higher measurement accuracy and responsiveness than the thermal type flow rate sensor.

Meanwhile, as described in Patent literature 1 and illustrated inFIG. 8(a), there is one pressure type mass flow controller100A that is, sequentially from an upstream side, provided with a fluid control valve V, and a first pressure sensor P1, fluid resistor L, and second pressure sensor P2 that constitute a pressure type flow rate sensor FS.

In the case of replacing the above-described thermal type mass flow controller in which the fluid control valve is present on a downstream side of the flow rate sensor by such a pressure type mass flow controller100A in which the fluid control valve V is provided on the upstream side of the pressure type flow rate sensor FS, a difference in mode of outputting a measured flow rate value from the flow rate sensor FS in the case of bringing the fluid control valve V to a fully closed state may become a problem.

That is, in the case of the above-described configuration of the thermal type mass flow controller, when the fluid control valve is fully closed, a measured flow rate value is substantially simultaneously outputted as zero, whereas in the case of the pressure type mass flow controller100A having the configuration as illustrated inFIG. 8(a), even when the fluid control valve V is fully closed, a measured flow rate value decreases over a predetermined time and asymptotically approaches zero. In the case where there is a difference in behavior of a measured flow rate value after the fluid control valve V has been fully closed, in the semiconductor manufacturing process that uses a measured flow rate value as a trigger to set up various types of sequences, it is necessary to redo threshold settings and the like, and perform other work, and therefore in some cases, it is not easy to replace a mass flow controller.

The reason why as described, in the mass flow controller100A having the configuration as illustrated inFIG. 8(a), a phenomenon appears in which even in the case of fully closing the fluid control valve V, the measured flow rate value does not instantaneously reach zero, is because the fluid remaining in the volume from the fluid control valve V to the fluid resistor L at the time of fully closing the fluid control valve V flows toward the downstream side.

Accordingly, by making the volume from the fluid control valve V to the fluid resistor L as small as possible, even in the above-described pressure type mass flow controller100A, a time necessary for the measured flow rate value to decrease to zero or a value near zero after the fluid control valve V has been fully closed can be shortened, and therefore the pressure type mass flow controller100A can be made to exhibit substantially the same behavior as that after the fluid control valve of the thermal type mass flow controller has been fully closed.

However, regarding the above-described volume, in particular, it is difficult to miniaturize the fluid control valve V to reduce the volume of the fluid control valve V.

More specifically, as illustrated inFIG. 8(b), the fluid control valve V is that is provided with: a valve seat block5A; a valve element member6A; an actuator3A provided with a piezo stack31A that drives the valve element member6A; and a coil spring SP for, in a state where voltage is not applied, restoring the piezo stack31A to an upper initial position. Also, the valve seat block5A is, as illustrated inFIG. 9, formed in a substantially cylindrical shape, and provided with: a first in-valve flow path51athat opens in a bottom surface part52A and in an upper surface part53A, and is formed inside of the valve seat block5A so as to be communicatively connected to an upstream side flow path; an L-shaped second in-valve flow path51bthat opens in the upper surface part53A and on a bottom part side of an outer circumferential surface59A, and formed inside of the valve seat block5A so as to be communicatively connected to a downstream side flow path23; and an annular-shaped protruded rim54A that is, in the upper surface part53A, protruded so as to surround an outflow opening of the first in-valve flow path51aand an inflow opening of the second in-valve flow path51bwithout space, and in an upper part, provided with a pressed surface55A that is pressed toward the bottom surface52A side at the time of assembling. As can be seen from two-dotted lines with arrows inFIGS. 8(b)and9, the fluid flowing from the upstream side flow path22flows in the order of the first in-valve flow path51a, an inner side part of the protruded rim54A in the upper surface part53A, the second in-valve flow path51b, a space between the outer circumferential surface and a body of the mass flow controller, and the downstream side flow path23.

In the case of attempting to miniaturize the valve seat block5A having such structure while keeping the same shape, and thereby reduce inside volume, in terms of space, it is difficult to form both of the first in-valve flow path51aand the second in-valve flow path51binside. Also, even in the case of being able to form both of the in-valve flow paths while miniaturizing the valve seat block5A, under the presence of the two in-valve flow paths, the inside volume cannot be reduced so much, and consequently, it is difficult to, in a short period of time, decrease to zero the measured flow rate value measured by the pressure type mass flow controller100A after the full closing.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

The present invention is made in consideration of the problem as described above, and intended to provide a fluid control valve of which a valve seat block has a configuration suitable to reduce inside volume, and a mass flow controller that uses the fluid control valve to, in a short period of time, decrease to zero a measured flow rate value measured after the fluid control valve has been fully closed.

Solution to Problem

The fluid control valve of the present invention is a fluid control valve configured to include a valve seat block and a valve element member, the valve seat block being provided with: an in-valve flow path that is formed inside of the valve seat block; and a valve seat surface that is brought into contact with or separated from a seating surface of the valve element member, wherein the valve seat block is further provided with: one end surface part that is at an upstream end of the in-valve flow path and formed with an inflow opening connected to an upstream side flow path; the other end surface part that is at a downstream end of the in-valve flow path and formed with an outflow opening through which fluid flowing in from the inflow opening flows outside the valve seat block; a protruded rim that is formed by being protruded by a predetermined height so as to surround the outflow opening in the other end surface part, and provided with a pressed surface that is pressed toward a one end surface part side during assembly; and a cutout that is formed in a part of the protruded rim so as to be communicatively connected to a downstream side flow path.

If so, the cutout is formed in the part of the protruded rim, and therefore the fluid having flowed from the upstream side flow path into the in-valve flow path can flow from the outflow opening to the downstream side flow path through the cutout.

Accordingly by only forming the single in-valve flow path inside the valve seat block, the fluid control valve can be configured between the upstream side flow path and the downstream side flow path together with the valve element member, so that it is necessary to form only one internal flow path, and therefore the valve seat block itself can be easily miniaturized to easily reduce the inside volume of the fluid control valve.

On the basis of this, in the case of using the fluid control valve of the present invention for a mass flow controller, the volume from the valve element member to the opening to the downstream side flow path in the fluid control valve can be made small, and therefore for example, the volume from the fluid control valve arranged on an upstream side to a flow rate sensor on a downstream side of the fluid control valve can also be made small. For this reason, an amount of the fluid that is accumulated between the fluid control valve and the flow rate sensor at the time of full closing can be made small, and therefore a measured flow rate value that is measured by the flow rate sensor after the fluid control valve has been fully closed can be made to approach zero in a short period of time. That is, the fluid control valve of the present invention enables characteristics of a measured flow rate value after the full closing to be made substantially the same as those of an existing mass flow controller used in a semiconductor manufacturing process, and therefore replacement is facilitated.

Even in the case of forming a plurality of cutouts, the fluid having passed through the cutouts once can be gathered and then flowed to the downstream side flow path, and in order to make it easy to ensure a predetermined amount of the fluid that can be flowed through the fluid control valve, it is only necessary that the fluid control valve is configured such that the fluid having flowed out from the outflow opening passes through the cutouts, moves along an outer circumferential surface of the valve seat block, and flows to the downstream side flow path.

In order to symmetrize deformation of the valve seat block caused by a force applied from the pressed surface during assembly, and maintain flatness of the valve seat surface that is brought into contact with the seating surface of the valve element member, it is only necessary that the protruded rim is formed in a substantially annular shape; and three cutouts are formed in a circumferential direction at regular intervals.

As a shape that is, in the case where the downstream side flow path is on the one end surface part side of the valve seat block in an assembled state, suitable to flow the fluid having passed through the cutout to the one end surface part side then moving the fluid along the outer circumferential surface, it is only necessary that the outer circumferential surface is formed as a side surface of a substantially two-step cylindrical shape of which a major diameter is on the other end surface part side and a minor diameter is on the one end surface part side; and on the other end surface part side of the outer circumferential surface, a cutoff part is formed by cutting off the vicinity of the cutout in an axial direction.

Configurations suitable to configure a normal close type fluid control valve in which in a state where the valve element member is in an initial position, the seating surface and the valve seat surface are in contact with each other include a configuration in which in the one end surface part, the valve seat surface is formed so as to surround the inflow opening.

In order to be able to prevent the valve seat surface formed in the one end surface part from being deformed during assembly by a pressing force from the pressed surface formed in the other end surface part, and thereby maintain flatness of the valve seat surface in the assembled state, it is only necessary that in the one end surface part, an annular concave groove, which has a smaller outside diameter size than an outside diameter size of the protruded rim, is formed so as to surround the inflow opening. If so, the deformation by the pressing force from the pressed surface substantially occurs in an outer part of the concave groove, so that on an inner side of the concave groove in the one end surface part, the deformation hardly occurs, and therefore the flatness of the valve seat surface can be maintained.

Configurations suitable to configure a normal open type fluid control valve in which in a state where the valve element member is in an initial position, the seating surface and the valve seat surface are separate from each other include a configuration in which in the other end surface part, the valve seat surface is formed on an inner side of the protruded rim that surrounds the outflow opening and the valve seat surface is protruded to a lower level than a level of the pressed surface.

In order to provide a configuration that is suitable to miniaturize the fluid control valve, and adapted such that the fluid from the upstream side flow path passes through the cutout from the outer circumferential surface of the valve seat block, flows into the inflow opening of the in-valve flow path, and then flows out from the outflow opening to the downstream side flow path, it is only necessary that the fluid control valve is a fluid control valve configured to include a valve seat block and a valve element member, the valve seat block being provided with: an in-valve flow path that is formed inside of the valve seat block; and a valve seat surface that is brought into contact with or separated from a seating surface of the valve element member, wherein the valve seat block is further provided with: a one end surface part that is at a downstream end of the in-valve flow path and formed with an outflow opening connected to a downstream side flow path; the other end surface part that is at an upstream end of the in-valve flow path and formed with an inflow opening through which fluid flows in from outside the valve seat block; a protruded rim that is protruded by a predetermined height so as to surround the inflow opening in the other end surface part, and provided with a pressed surface that is pressed toward a one end surface part side during assembly; and a cutout that is formed in a part of the protruded rim so as to be communicatively connected to an upstream side flow path.

A mass flow controller is provided with: the fluid control valve of the present invention; and a flow rate sensor that is provided on a downstream side of the fluid control valve enables the volume from the fluid control valve to the flow rate sensor to be made very small, and a value of a measured flow rate value to be decreased to zero or a value near zero in a short period of time after the fluid control valve has been fully closed.

Advantageous Effects of Invention

As described, according to the present invention, as a result of forming the cutout in the part of the protruded rim that is formed by being protruded so as to surround the outflow opening of the in-valve flow path in the other end surface part and has a pressed surface, only by providing the single in-valve flow path, the fluid can be flowed from the upstream side flow path to the downstream flow path through the valve seat block. Accordingly, a new flow path configuration that eliminates the need to provide a plurality of in-valve flow paths is provided, so that miniaturization can be achieved with a function of the valve seat block being kept, and consequently the volume of the fluid control valve can be reduced. Because the volume can be reduced as described, an amount of the fluid that flows after the fluid control valve has been fully closed can be made small, and therefore a time necessary for a measured flow rate value measured by the flow rate sensor present in a subsequent stage to reach zero or near zero can be shortened. Also, the mass flow controller using the fluid control valve of the present invention enables the characteristics after the fluid control valve has been fully closed to be made substantially the same as those of a conventionally used one, and therefore replacement of an existing mass flow controller can be facilitated.

DESCRIPTION OF EMBODIMENTS

First Embodiment

A fluid control valve V and a mass flow controller100according to a first embodiment of the present invention are described with reference toFIGS. 1 to 4.

The mass flow controller100of the first embodiment is one that is used for a semiconductor manufacturing apparatus, and as illustrated inFIG. 1, provided with: a body1inside which a flow path2through which fluid as a measuring target flows is formed; a primary stage pressure sensor P for measuring pressure at the time when the fluid flowing through the flow path2flows into the body1, or measuring pressure on an upstream side before the fluid flows into the body1; a fluid control valve V for controlling a flow rate of the fluid flowing through the flow path2; a flow rate sensor FS for measuring the flow rate of the fluid flowing through the flow path2; and a control part (not illustrated) that performs feedback control of an opening level of the fluid control valve V so as to minimize a deviation between a target flow rate value and a measured flow rate value measured by the flow rate sensor FS.

Note that the primary stage pressure sensor P, the fluid control valve V, and the flow rate sensor FS are provided sequentially from the upstream side in this order. That is, the flow rate sensor FS is provided on a downstream side of the fluid control valve V.

The respective parts are described in detail.

The body1is one formed in a blockish shape inside which the above-described flow path2penetrates, and an upstream end of the flow path2is connected to an external inflow pipe (not illustrated) as an inlet port IP, whereas a downstream end is connected to an external outflow pipe (not illustrated) as an outlet port OP. Also, the flow path2formed inside the body1is configured to include: a first flow path21that connects the inlet port IP and the primary stage pressure sensor P to each other; a second flow path22that connects the primary stage pressure sensor P and the fluid control valve V to each other; a third flow path23that connects the fluid control valve V and an after-mentioned laminar flow element L to each other; a fourth flow path24that connects the laminar flow element L and an after-mentioned second pressure sensor P2 to each other; and a fifth flow path25that makes a connection from the second pressure sensor P2 to the outlet port OP. As can be seen inFIG. 1, a diameter of the third flow path23that makes the connection between the fluid control valve V and the laminar flow element L is formed to be thinner than at least those of the first and second flow paths21and22present on the upstream side to reduce the volume from the fluid control valve V to the laminar flow element L.

Note that in the following description, in particular, in the case of describing matters related to the fluid control valve V, the second flow path22and the third flow path23are also referred to as an upstream side flow path and a downstream side flow path, respectively.

The primary stage pressure sensor P is provided to measure an upstream side pressure change of the fluid flowing from the external inflow pipe, and for example, the control part is configured to switch a control rule for the feedback control on the basis of a measured pressure value measured by the primary stage pressure sensor P.

Various types of flow rate sensors can be used as the flow rate sensor FS; however, herein, a so-called pressure type flow rate sensor FS having good flow rate measurement accuracy and responsiveness is employed. The pressure type flow rate sensor FS is one that includes, sequentially from the upstream side, a first pressure sensor P1 that measures pressure on a downstream side of the fluid control valve V, the laminar flow element L as a fluid resistor, and the second pressure sensor P2 that measures pressure on a downstream side of the laminar flow element L. The laminar flow element L causes a pressure difference between before and after the laminar flow element L, and the flow rate is measured on the basis of the respective pressures measured by the first and second pressure sensors P1 and P2. Also, the first embodiment is adapted to, for example, arrange the laminar flow element L inside the body1so as to position the laminar flow element L at substantially the center in terms of a height dimension of the body1, and make a distance from the fluid control valve V present on an upper surface side of the body1to the laminar flow element L short to reduce the volume of the third flow path23that makes the connection between the fluid control valve V and the laminar flow element L.

The fluid control valve V is provided so as to make a connection between the second flow path22as the upstream side flow path and the third flow path23as the downstream side flow path, and controls the flow rate of the fluid that can pass depending on a separation distance between a valve seat block5and a valve element member6. That is, the fluid control valve V is one that is, as illustrated inFIGS. 1 and 2, sequentially from an upper side, provided with an actuator3, a plunger4, a valve seat block5, a valve element member6, a leaf spring7, and a supporting member8. More specifically, the separation distance between the valve seat block5and the valve element member6is adjusted by the movement of the actuator3, which is transferred to the valve element member6through the plunger4. Also, the leaf spring7is one that is, as illustrated inFIG. 2, formed with a central through-hole and a plurality of slits for making the fluid pass, and adapted to configure a normal close type that presses the valve element member6up from the supporting member8toward the actuator3side, and in an initial state, makes the valve element member6and the valve seat block5keep in contact with each other.

The actuator3is one that is provided with, for example, a piezo stack31formed by stacking a plurality of piezo elements. Regarding a casing member32containing the piezo stack31, a flange part attached to the body1and a cylindrical part containing the piezo stack31are formed as one member. The casing is formed of a member having a low thermal expansion coefficient, such as Invar, and adapted to hardly exhibit thermal deformation. Accordingly, the casing is hardly influenced by ambient temperature, temperature of the fluid, or the like, so that regardless of temperature, a displacement amount according to voltage applied to the piezo stack31can be provided, and therefore hysteresis in voltage-displacement characteristics can be made small.

The plunger4is configured to include: an annular part41that is formed in an outer circumferential part, and during assembly, presses an after-mentioned pressed surface55of the valve seat block5toward a bottom surface side as a result of fixation of the flange part of the casing member32; a rod-like part42that is formed in the central part, and transfers the displacement of the piezo stack31to the valve element member6; and a diaphragm part43that connects the annular part41and the rod-like part42to each other. The plunger4is formed of a material having good elasticity such as aluminum so as to, in a state where voltage is not applied to the actuator3, generate a repulsive force in the diaphragm part43that restores the piezo stack31to the initial position. Accordingly, as opposed to the fluid control valve V in the conventional example inFIG. 8, the need for the coil spring SP or the like for restoring the piezo stack31to the initial position is eliminated, which contributes to simplification of the configuration of the fluid control valve V as well as miniaturization.

The valve seat block5is, as illustrated inFIGS. 2 to 4, in a bottom surface part52corresponding to one end surface part thereof, formed with a valve seat surface58that is brought into contact with a seating surface61of the valve element member6; formed in a substantially two-step cylindrical shape of which a minor diameter is on a bottom surface side and a major diameter is on an upper surfaced side; and in the central part, formed with an in-valve flow path51that extends in an axial direction.

More specifically, the valve seat block5is characterized by being provided with: the bottom surface part52that is at an upstream end of the in-valve flow path51and corresponds to the one end surface part formed with an inflow opening511connected to the upstream side flow path; an upper surface part53that is at a downstream end of the in-valve flow path51and corresponds to the other end surface part formed with an outflow opening512through which the fluid flowing in from the inflow opening511flows outside the valve seat block5; a protruded rim54that is, in the upper surface part53, formed by being protruded by a predetermined height so as to surround the outflow opening512, and in an upper part thereof, provided with a pressed surface55that is, during assembly, pressed toward the bottom surface part52side; and cutouts541that are formed in parts of the protruded rim54so as to be communicatively connected to the downstream side flow path. Note that the bottom surface part52and the upper surface part53are not limited to being arranged only in a vertical direction, differently from the illustrated ones, and for example, in a state where the valve seat block5is assembled in a concave part11of the body1, a side corresponding to an inner side and a side facing outward can be respectively defined as the bottom surface part52and the upper surface part53.

In the upper surface part53, the protruded rim54of a substantially annular shape is protruded in an outermost circumferential part in the axial direction. In other words, the upper surface part53is, as illustrated in a top view ofFIG. 3(a), formed with: a substantially circular shaped outflow plane56on which the outflow opening512opens inward; and the pressed surface55of an annular beltlike shape adjacent to the outside of the outflow plane56, and adapted to make a level of the pressed surface55higher than that of the outflow plane56. The protruded rim54functions as a spacer for, in the case where the diaphragm part43of the plunger4is pressed and deformed by the actuator3, preventing the diaphragm part43from interfering with the outflow plane56of the upper surface part53. Further, the pressed surface is formed only on an upper surface of the annular protruded rim54that is formed in the outermost circumference part in the upper surface part53, and therefore at the time of being pressed, makes deformation of the valve seat block5less likely to arrive at the valve seat surface58formed in the bottom surface part52, so that flatness of the valve seat surface58can be maintained. Also, in another expression, the pressed surface55of the protruded rim54is configured to be pressed during assembly by the annular part41of the plunger4present on the upper side, and also on the basis of a resultant counterforce, press the annular part41of the plunger4.

The protruded rim54is, as illustrated inFIG. 4, formed with the three cutouts541at regular intervals, i.e., at every120degrees in a circumferential direction. Also, as illustrated in an enlarged view ofFIG. 3(b), in the vicinity of each of the cutouts541, a cutoff part542formed by cutting off the vicinity of the cutout541part in the axial direction on the upper surface part53side of an outer circumferential surface59is formed.

In the bottom surface part52, the valve seat surface58is formed so as to surround the inflow opening511in the bottom surface part52, and on an outer side of the valve seat surface58, an annular concave groove57having a smaller outside diameter size than the protruded rim54is formed so as to surround the inflow opening511. Because of the presence of the concave groove57, even in the case where the pressed surface55is pressed during assembly, the deformation of the valve seat block5on the bottom surface part52side is limited to a substantially outer circumferential side, and therefore the flatness of the valve seat surface58can be maintained. Accordingly, a preferable degree of contact with the seating surface61of the valve element member6can be constantly maintained, and therefore a sealing function of a valve can be fulfilled.

Further, the valve seat block5is assembled by being fitted into the concave part11of a cylindrical shape provided in the body1. The concave part11is arranged so as to separate the second and third flow paths22and23of the body1from each other, and the second flow path22as the upstream side flow path is adapted to open at the bottom surface central part of the concave part11, whereas the third flow path23as the downstream side flow path is adapted to open at a position that is at the central part of the outer circumferential surface59of the concave part11and corresponds to a minor diameter part of the valve seat block5.

Still further, in the state where the valve seat block5is fitted into the concave part11, a part other than the cutoff parts542in a major diameter part on the upper surface part53side of the valve seat member is adapted to be fitted on an inner circumferential surface of the concave part11without space, whereas the minor diameter part on the bottom surface part52side of the valve seat block5is adapted to be formed with a space between the minor diameter part and the inner circumferential surface of the concave part11.

Accordingly, as illustrated inFIG. 4, the fluid flowing from the upstream side flow path into the in-valve flow path51moves toward the upper surface part53of the valve seat block5in the axial direction, and when flowing out of the outflow opening512, flows in radial directions to arrive at the cutouts541formed in the protruded rim54. Then, the fluid having arrived at the cutout541parts passes between the cutoff parts542adjacent to the cutouts541and the inner circumferential surface of the concave part11, moves along the outer circumferential surface59of the valve seat block5, and arrives at the space between the minor diameter part of the valve seat block5and the inner circumferential surface of the concave part11. Finally, the fluid flows to the downstream side flow path that opens to the space.

That is, the present embodiment is adapted such that the fluid rises out from the in-valve flow path51inside the valve seat block5to the upper surface part53, then moves along the outer circumferential surface59, and flows to the downstream side flow path.

As described, according to the valve seat block5of the first embodiment, the number of in-valve flow paths51, which has conventionally required two, can be reduced to one, and a function of the fluid control valve V can be fulfilled, so that it is only necessary to form the single in-valve flow path51, and therefore miniaturization is facilitated.

Accordingly, because volume of the fluid control valve V can also be made small, the volume from the fluid control valve V to the laminar flow element L can be made much smaller than before, and therefore an amount of the fluid that flows to the flow rate sensor FS after the fluid control valve V has been fully closed can be reduced.

For this reason, even in the case of the mass flow controller100having the configuration in which the flow rate sensor FS is provided on the downstream side of the fluid control valve V, a measured flow rate value that is measured by the flow rate sensor FS after the fluid control valve V has been fully closed can reach zero or a value near zero in a short period of time.

That is, characteristics very close to characteristics of an existing mass flow controller, which is used in a semiconductor manufacturing process, at the time of fully closing a fluid control valve can be achieved, and therefore the existing mass flow controller can be easily replaced by the mass flow controller100of the first embodiment.

Also, the three cutouts541that are formed in place of forming the second in-valve flow path51are formed so as to be rotationally symmetric with respect to the protruded rim54formed with the pressed surface55, so that the deformation of the valve seat block5at the time of pressing the pressed surface55can be made uniform, and therefore an adverse influence on the flatness of the valve seat surface58or the like can be prevented.

Accordingly, basic functions of the fluid control valve V, such as sealing performance, can be prevented from being frustrated by a miniaturization-induced change in configuration of the flow path2in the valve seat block5.

Second Embodiment

Next, a second embodiment is described with reference toFIGS. 5 and 6. Note that members corresponding to those in the first embodiment are affixed with the same letters or numerals.

A mass flow controller100of the second embodiment is, as compared with that of the first embodiment, different in configuration of a fluid control valve V, in particular, configuration of a valve seat block5.

More specifically, the fluid control valve V of the second embodiment is configured to be of a normal open type, and as illustrated inFIG. 5, from an upper side, includes an actuator3, valve element member6, and valve seat block5.

The valve element member6is one that has a shape corresponding to the plunger4in the first embodiment, and also has diaphragm structure of which a bottom surface is formed flush and thereby made to serve as a seating surface61. The valve element member6is adapted to be able to adjust a separation distance between the seating surface61and a valve seat surface58in such a way that voltage is applied to the actuator3to give rise to deformation, which causes the central part to be pressed, and thereby a diaphragm part62is elastically deformed toward the valve seat block5side. Also, in the case where voltage is not applied to the actuator3, as illustrated inFIG. 5, the seating surface61and the valve seat surface58are separate from each other, and therefore in an initial state, an open state is maintained.

The valve seat block5is, as illustrated inFIGS. 5 and 6, formed with the valve seat surface58that, in an upper surface part53, surrounds an outflow opening512on an inner side of a protruded rim54, and is also protruded to a level lower than a level of a pressed surface55.

Even with such a valve seat block5, substantially the same fluid flow as that in the first embodiment as illustrated inFIG. 6can be formed, and therefore substantially the same effect as that of the first embodiment can be obtained.

That is, the valve seat block5of the present invention can be used for any of the normal close type and normal open type fluid control valves V.

Other embodiments are described.

In any of the above-described embodiments, the valve seat block5is formed with the cutoff parts542on the outer circumferential surface59near the cutouts541to, between the valve seat block5and the concave part11, form the spaces through which the fluid passes; however, as illustrated inFIGS. 7(a) and (b), the present invention may be adapted such that the outer circumferential surface on the upper surface part53side of the valve seat block is formed as a completely cylindrical side surface, and by designing a shape of the concave part11side, the spaces are formed. That is, as illustrated inFIGS. 7(a) and (b), the present invention may be adapted to, on the inner circumferential surface of the concave part11, form vertical grooves543that protrude outward in radial directions and extend in the axial direction, and form the spaces between the concave part11and the outer circumferential surface59of the valve seat block5. In addition, as illustrated inFIG. 7, in the case of forming the vertical grooves543in order to form the spaces between the outer circumferential surface59of the valve seat block5and the inner circumferential surface of the concave part11, it is necessary to perform positioning so as to align the cutouts541with corresponding vertical grooves543in position during assembly. On the other hand, as in any of the above-described embodiments, in the case where the valve seat block5has the cutoff parts542on the outer circumferential surface59near the cutouts541, and the concave part11is formed in the cylindrical shape, the positioning as described above is not required, and therefore assembling is very easy.

Further, any of the above-described embodiments is configured such that, in the fluid control valve, the fluid flows in the order of the upstream side flow path, in-valve flow path, upper surface part, cutouts, outer circumferential surface, and downstream side flow path; however, even in the case of reversing the flow of the fluid, miniaturization can be achieved in a similar manner. That is, the present invention may be a fluid control valve configured to include a valve seat block and a valve element member, wherein the valve seat block is provided with an in-valve flow path that is formed inside of the valve seat block, and a valve seat surface that is brought into contact with or separated from a seating surface of the valve element member, and the valve seat block is further provided with; one end surface part that is at a downstream end of the in-valve flow path and formed with an outflow opening connected to a downstream side flow path; the other end surface part that is at an upstream end of the in-valve flow path and formed with an inflow opening into which fluid flows from outside the valve seat block; a protruded rim that is protruded by a predetermined height so as to surround the inflow opening in the other end surface part, and is provided with a pressed surface that is pressed toward the one end surface part side during assembly; and a cutout that is formed in a part of the protruded rim so as to be communicatively connected to an upstream side flow path.

In any of the above-described embodiments, in the valve seat block, the protruded rim is formed by being protruded from the upper surface part, and molded as an integrated object; however, for example, only the protruded part may be configured as another member. Even with such a protruded rim part, in the case where the valve seat block is assembled by being pressed toward the bottom surface part side, a function as a spacer, and an effect of preventing the deformation of the valve seat block due to a pressing force on the pressed surface from arriving at the valve seat surface, and maintaining flatness can be obtained. In addition, as described, in the case where only the protruded rim is configured as a separate body, when in order to form the deformation of the valve seat block during assembly in a symmetric shape, attempting to arrange the protruded rim and the cutouts in the upper surface part at the time of assembling as illustrated inFIGS. 3(a) and (b)orFIG. 7, it is necessary to perform strict positioning or use some sort of jig. On the other hand, as in any of the above-described embodiments, in the case of the valve seat block in which the protruded rim is also integrated with a main body part, without particularly performing positioning, the protruded rim and cutouts in the upper surface part can be positioned as desired, and therefore the deformation of the valve seat block can be performed in a desirable symmetric shape. Accordingly, even after miniaturization, flatness of the valve seat surface can be easily provided to easily obtain the sealing function or the like of the flow rate control valve.

In each of the above-described embodiments, the number of cutouts formed in the protruded rim is three; however, the number of cutouts may be one or another number. It is only necessary to set the number of cutouts in consideration of a balance between the cutouts and the pressed surface so as to be able to keep a function of the pressed surface.

Also, depending on a position of the downstream side flow path opening to the concave part, the cutoff parts are not necessarily provided. For example, it is only necessary to open the downstream side flow path to the concave part at a position corresponding to any of the cutouts in an assembled state.

In any of the above-described embodiments, a shape of the valve seat block is the substantially cylindrical shape; however, the valve seat block may be formed in another shape such as a quadrangular prism.

In any of the above-described embodiments, the mass flow controller that is provided with the pressure type flow rate sensor on the downstream side of the fluid control valve is described; however, even in the case where the flow rate sensor is a thermal type flow rate sensor, the effect of the present invention can be obtained.

Also, in addition to using the valve seat block of the present invention to make the characteristics of a measured flow rate value after fully closing the fluid control valve meet desired characteristics, the valve seat block of the present invention may also be used in the case of desiring to miniaturize a single body of the fluid control valve. For example, the valve seat block of the present invention may be used in order to miniaturize the whole of a mass flow controller that is provided with a flow rate sensor on an upstream side of a fluid control valve. In short, the valve seat block of the present invention can also be used for the purpose of miniaturization along with realizing a function of the fluid control valve.

In any of the above-described embodiments, the fluid control valve is used to control the flow rate of the fluid; however, the fluid control valve may be used to control pressure of the fluid. As the fluid to be controlled, any of liquid and gas is possible.

In addition, various modifications and combinations of the embodiments may be made unless contrary to the scope of the present invention.

REFERENCE CHARACTER LIST