JP2016035462A - Measurement mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a short internal channel in a pressure-type flow measurement mechanism with a small number of components, while maintaining compactness.SOLUTION: There is provided a measurement mechanism including a body 1 that has an internal channel through which a measurement target fluid, a recess 1h that is formed to be open to the outer surface of the body to divide the internal channel 1a, a fluid resistance member 3 that is accommodated inside the recess, and a fluid measuring instrument 10 that is attached to the body to close the opening of the recess to the outer surface of the body to detect the physical amount related to the flow rate of the measurement target fluid, where the fluid resistance member is pressed against the body while a housing of the fluid measuring instrument is attached to the body, and a sensor element of the fluid measuring instrument is arranged outside the recess.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a so-called pressure-type flow rate measuring mechanism that measures the flow rate of a fluid flowing through a resistance flow path according to upstream and downstream pressures of the fluid resistance, and a mass flow controller using the so-called pressure type flow rate measuring mechanism.

  This type of flow measurement mechanism measures the fluid pressure upstream and downstream of the resistance flow path represented by a restrictor, nozzle, etc., and based on the pressure value and the resistance value of the resistance flow path, It measures the mass flow rate of the fluid flowing through the passage.

  As an example, as shown in FIG. 14, there is an integrated body 1 ′ having a block shape with a pressure sensor 2 ′ and a fluid resistance member 3 ′ forming a resistance flow path 3 a ′ attached thereto. The flow rate measurement mechanism 10 ′ forms an internal channel 1a ′ through which a fluid to be measured flows in the body 1 ′, and the resistance channel 3a ′ is interposed in the middle of the internal channel 1a ′. The fluid resistance member 3 ′ is embedded in the body 1 ′.

  At this time, the fluid resistance member 3 ′ is disposed on the opposite surface of the body 1 ′ from the pressure sensor 2 ′, and the fluid resistance member 3 ′ is accommodated in the recess 1 b ′ provided on the surface. ing. The reason why the fluid resistance member 3 ′ is not provided in series with the pressure sensor 2 ′ on the same surface of the body 1 ′ is that the body 1 ′ becomes long and obstructs compactness.

  However, with this configuration, the internal flow path 1a ′ extends from the mounting surface of the pressure sensor 2 ′ in the body 1 ′ to the mounting surface of the fluid resistance member 3 ′ on the opposite side, and its length is long. It tends to be. For example, as shown in the figure, when the mass flow controller 100 ′ is configured by attaching the flow rate adjusting valve 4 ′ to the front stage of the flow rate measuring mechanism 10 ′, the resistance flow path 3a ′ from the valve body of the flow rate adjusting valve 4 ′. The volume of the internal flow path 1a ′ is increased.

For this reason, it takes time until the fluid accumulated in the internal flow path 1a ′ exits the resistance flow path 3a ′ after the flow rate adjustment valve 4 ′ is closed, resulting in poor flow rate controllability (responsiveness). Can occur.
Furthermore, since a dedicated lid or packing for closing the concave portion 1b 'is required, the structure may be complicated or many seal members may be required, resulting in high costs.

  On the other hand, as shown in Patent Document 1, it is considered that the body is divided into two in the longitudinal direction, and the internal flow path is divided, and a fluid resistance member is sandwiched between them. Therefore, it is still difficult to avoid a complicated structure and an increased number of parts.

JP-T-2004-510225

  The present invention has been made in view of the above-described problems, and the main problem is that a fluid measuring device and a fluid resistance member are attached to a body having an internal flow path and flow through the internal flow path. In a so-called flow measurement mechanism configured to measure the flow rate of fluid, a short internal flow path is realized with a small number of parts while maintaining compactness.

  That is, the flow rate measuring mechanism according to the present invention communicates the body having the internal flow path through which the fluid to be measured flows, the upstream internal flow path and the downstream internal flow path which are separated from the internal flow path. A fluid resistance member having a resistance flow path; and a fluid measurement device that detects a physical quantity related to the flow rate of the fluid, so that the flow rate of the fluid can be calculated based on the physical quantity detected by the fluid measurement device. In the constructed flow measurement mechanism, the fluid resistance member is formed so as to pass through the communication path, and the fluid resistance member is disposed between the body and the fluid measuring device. In the state, either one of the internal flow paths and the inlet provided in the fluid measuring device communicate with each other through the communication path, and the other of the internal flow paths and the communication path are connected to the resistance flow path. Through the ream It is characterized in that it has configured to.

  If it is such, since the fluid measuring device and the fluid resistance member are laminated on the same side of the body, the internal flow path length between them can be shortened as much as possible. Therefore, it becomes possible to improve the responsiveness of flow rate sensing. In addition, since the fluid measuring device is stacked on the fluid resistance member, it is possible to prevent the body from becoming unnecessarily long. Further, since the body is not divided and special members are not required, the structure is not complicated and the number of parts is not increased.

  If the fluid resistance measuring device is attached to the body so that the fluid resistance member is held by being sandwiched between them, the pressure sensor directly serves as a fixture for the body of the fluid resistance member. Therefore, parts can be reduced.

  As a specific aspect that can be made more compact and that can be suitably sealed, a recess in which the upstream internal flow channel and the downstream internal flow channel open on the side surface or the bottom surface is opened on the outer surface of the body. The fluid resistance member is housed in the recess and the fluid measuring device is attached to the body so that the mounting surface of the pressure sensor seals the opening of the recess and holds the fluid resistance member. Things can be mentioned.

  As a specific embodiment of the fluid measuring device, the fluid measuring device is a pressure sensor that detects the pressure of at least one of the upstream internal flow path and the downstream internal passage, and the pressure sensor Examples include a configuration in which the flow rate of the fluid can be calculated based on the detected fluid pressure.

  As another specific embodiment of the flow rate measuring device of the present invention, the fluid measuring device is shunted by the fluid resistance member, and a part of the fluid introduced from the inlet is the internal flow. It may be a thermal flow sensor provided with a sensor flow path having a lead-out port led out to the other side of the path.

  In order to form a mass flow controller using this flow rate measurement mechanism, the flow rate adjustment valve attached to the body and the flow rate adjustment valve are controlled so that the flow rate measured by the flow rate measurement mechanism becomes a predetermined target flow rate. A control circuit may be provided.

  If the pressure sensor and the flow rate adjusting valve are attached to only one specific surface of the body, it is possible to reduce the size when a plurality of pressure sensors and flow rate adjustment valves are provided.

  In such a case, since the fluid measuring device and the fluid resistance member are laminated on the same side of the body, the internal flow path length between them can be shortened as much as possible, and the response of flow sensing can be improved. It becomes possible to improve. Further, since the fluid measuring device is laminated on the fluid resistance member, it is possible to prevent the body from becoming unnecessarily long, and it does not cause a complicated structure or an increase in the number of parts.

Fluid circuit diagram of mass flow controller in one embodiment of the present invention The whole perspective view of the mass flow controller in the embodiment. The longitudinal cross-sectional view which shows the internal structure of the massflow controller in the embodiment. The top view of the massflow controller in the embodiment. The cross-sectional view which shows the internal structure of the pressure sensor in the embodiment. The disassembled perspective view of the massflow controller in the embodiment. The fragmentary sectional view which shows the internal structure of the flow regulating valve in the embodiment. The fragmentary sectional view which shows the internal structure of the flow regulating valve in the embodiment. The fragmentary sectional view which shows the internal structure in the state which accommodated the fluid resistance member in the same embodiment in the recessed part. The longitudinal cross-sectional view which shows the internal structure of the massflow controller in other embodiment of this invention. The fluid circuit diagram of the mass flow controller in another embodiment of this invention. The whole perspective view of the mass flow controller in another embodiment. The longitudinal cross-sectional view which shows the internal structure of the massflow controller in another embodiment. The longitudinal cross-sectional view which shows the internal structure of the conventional massflow controller.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
A mass flow controller 100 according to the present embodiment is mounted on, for example, a gas panel and constitutes a part of a material supply line of a semiconductor manufacturing apparatus. FIG. 1 shows a fluid circuit diagram, and FIG. 2 shows an overall perspective view. In addition, an internal flow path 1a for flowing a fluid to be flow controlled, a flow rate adjustment valve 4 provided on the internal flow path 1a, and a downstream side of the flow rate adjustment valve 4, the internal flow path 1a And a control circuit 6 (shown in FIG. 1) for controlling the flow rate adjusting valve 4 so that the flow rate measured by the flow rate measurement mechanism 10 becomes a predetermined target flow rate. Not). Each part is described in detail below.

  As shown in FIG. 3, the internal flow path 1 a is formed in a body 1 having a long and thin rectangular parallelepiped shape, and the fluid inlet port 1 d and the fluid outlet port 1 e are arranged at both ends orthogonal to the longitudinal direction of the body 1. Each of the surfaces is opened so that the fluid flows along the longitudinal direction when viewed from a direction orthogonal to the component mounting surface 1c (hereinafter also referred to as a plan view).

  By the way, one surface parallel to the longitudinal direction of the body 1 is set as a component mounting surface 1c, and the flow regulating valve 4, the pressure sensors 21, 22 and the like are mounted only on the component mounting surface 1c. It is configured. Further, the surface opposite to the mounting surface 1c is a fixing surface for fixing the body 1 to a panel or the like. Furthermore, it is configured so that nothing is attached to the other two surfaces (hereinafter referred to as side surfaces) parallel to the longitudinal direction so that the side surfaces of the plurality of bodies 1 can be arranged in close contact or close to each other. is there.

  As shown in FIGS. 3, 6, and 7, the flow rate adjusting valve 4 has a substantially cylindrical shape including a valve seat member 42 and a valve body member 41, and the longitudinal direction of the component 1 on the component mounting surface 1 c of the body 1. It is vertically attached to one end of the direction. Further, the width dimension is set smaller than or equal to the width dimension (dimension in the direction perpendicular to the longitudinal direction) of the component mounting surface 1c. As shown in FIG. In the state attached to the body 1, the flow rate adjusting valve 4 is configured not to protrude in the width direction from the body 1.

  More specifically, as shown in FIGS. 6 and 7, the valve seat member 42 has a cylindrical shape in which a protruding annular valve seat 42 a is formed at the center of the top surface. It fits into a bottomed recess 1f opened at one end of the component mounting surface 1c. And this bottomed recessed part 1f is provided in the position which divides the said internal flow path 1a, and the upstream internal flow of the divided | segmented internal flow paths 1a is formed in the bottom center part of this bottomed recessed part 1f. The end of the path 1a (1) is opened. In addition, the bottom end side peripheral surface of the bottomed recess 1f is opened at the start end of the internal flow channel 1a (2) on the downstream side.

  One end of the valve seat member 42 opens to the inside of the valve seat 42 a on the top surface of the valve seat member 42, and the other end of the valve seat member 42 opens to a central portion of the bottom surface of the valve seat member 42; One end opens to the outside of the valve seat 42a on the top surface of the valve seat member 42, and the other end passes through a fluid outlet path 42c that opens to the peripheral edge of the bottom surface of the valve seat member 42.

  In the state where the valve seat member 42 is fitted in the bottomed recess 1f, the other end of the fluid introduction path 42b is sealed at the end of the upstream internal flow path 1a (1) that opens at the center of the bottomed recess 1f. It communicates via member SL2. Further, since the other end of the fluid lead-out path 42c has a gap between the bottom peripheral edge portion of the valve seat member 42 and the inner peripheral surface of the bottomed recess 1f from the bottom peripheral edge portion to the side peripheral surface bottom portion, It communicates with the beginning of 1a (2).

  On the other hand, as shown in FIGS. 3, 7, and 8, the valve body member 41 includes a casing 411 configured to be airtight inside and a columnar stack accommodated in the casing 411. And a piezoelectric element 412. The casing 411 includes a cylindrical body 411a having a substantially cylindrical shape, an elastically deformable thin plate-like diaphragm member 411b that seals the base end surface of the cylindrical body 411a, and a distal end portion of the cylindrical body 411a in the axial direction. It comprises an initial adjustment screw 411d attached so as to be able to advance and retreat, and a bellows member 411c that can be expanded and contracted in the axial direction to seal the screwed portion between the initial adjustment screw 411d and the cylindrical body 411a. Is joined to the inner surface of the diaphragm member 411b, and the other end of the laminated piezoelectric element 412 is joined to the tip of the initial adjustment screw 411d. And by attaching the base end surface of the said cylindrical body 411a to the component attachment surface 1c of the body 1 via sealing member SL1, while sealing the opening of the said bottomed recessed part 1f formed in the body 1, with this base end surface, The diaphragm member 411b is opposed to the valve seat 42a, and the distance between the diaphragm member 411b and the valve seat 42a is changed by the expansion and contraction of the piezoelectric element 412, so that the diaphragm member 411b functions as the valve body 41a.

  In terms of a fluid circuit, the flow rate measuring mechanism 10 includes a resistance channel 3a provided on the internal channel 1a, and an internal channel 1a on the upstream side and the downstream side of the resistance channel 3a, as shown in FIG. The flow rate of the fluid flowing through the internal flow path 1a is determined based on the pressure measurement values by the pressure sensors 21 and 22 and the resistance value of the resistance flow path 3a. It is configured to be measurable. Here, the pressure sensors 21 and 22 correspond to the fluid measuring device in the claims.

  Each part will be described. The said resistance flow path 3a is formed in the rectangular parallelepiped fluid resistance member 3 which laminated | stacked several rectangular thin plates 31-35, as shown in FIG. 6, FIG. That is, as shown in FIG. 6, each thin plate or a part of the thin plate overlaps with each other when laminated and penetrates in the laminating direction and penetrates through the hole 3 b and penetrates in the face plate direction and extends in the longitudinal direction. When a plurality of slits 3d are provided and the thin plates 31 to 35 are laminated, the resistance flow path 3a is formed by the slits 3d. The flow path resistance can be adjusted by changing the shape and number of the slits 3d. Further, in the present embodiment, a part of the slit 3d provided in the central portion of the rectangular thin plate 31 laminated on the uppermost surface overlaps the through hole 3b of the rectangular thin plate 32 just below the rectangular thin plate 31, so that the communication path 3c is configured. The pressure inlet 2a1 is in contact with the slit 3d at the center of the rectangular plate 31 on the uppermost surface so that the pressure in the upstream internal flow path 1a (2) is introduced.

  On the other hand, as shown in FIGS. 3, 6, and 9, a rectangular recess 1h is provided at the center in the longitudinal direction of the component mounting surface 1c of the body 1 so as to divide the internal flow path 1a. The fluid resistance member 3 is attached to the recess 1h by being fitted with a gap in the longitudinal direction of the body 1 without a gap in the width direction. In addition, at the center of the bottom surface of the recess 1h, the end of the upstream internal flow channel 1a (2) of the internal flow channel 1a divided by the recess 1h opens, while the bottom surface in the longitudinal direction of the bottomed recess 1f. In the edge part, it is comprised so that the start end of the downstream internal flow path 1a (3) may open.

  Thus, in a state where the fluid resistance member 3 is fitted in the recess 1h, one end on the bottom side of the communication path 3c is connected to the end of the upstream side internal flow path 1a (2) via the seal member SL3, The resistance flow path 3a communicates with the start end of the downstream side internal flow path 1a (3). That is, the upstream internal flow path 1a (2) is connected to the downstream internal flow path 1a (3) via the communication path 3c and the resistance flow path 3a.

  As shown in FIGS. 3, 5, 9, and the like, the pressure sensors 21 and 22 include a main body 2A having a flat shape and a sensor element such as a piezoelectric element (not shown) housed in the main body 2A. The flat main body portion 2A is set so that the face plate portion is perpendicular to the component mounting surface 1c and parallel to the longitudinal direction of the body 1 with respect to the component mounting surface 1c of the body 1. It is attached. Further, as shown in FIG. 4 and the like, the thickness dimension of the pressure sensors 21 and 22 is set smaller than or equal to the width dimension orthogonal to the longitudinal direction of the component mounting surface 1c, and the pressure sensor 21 in the mounted state. , 22 does not protrude in the width direction from the body 1.

In the main body 2A, a fluid filling chamber 2b having a pressure-sensitive surface 2b1 formed on the inner surface, a pressure inlet 2a1 (corresponding to an inlet in the claims) provided on the mounting surface 2a for the body 1, and the fluid filling chamber A fluid introduction passage 2c communicating with 2b is provided, and the sensor element detects the amount of displacement of the pressure-sensitive surface 2b1 received by pressure and outputs it as a pressure signal. The fluid filling chamber 2b has a thin disk shape formed in the main body 2A, and one face plate portion of the fluid filling chamber 2b is used as the pressure sensitive surface 2b1. The pressure-sensitive surface 2b1 is set to be parallel to the longitudinal direction of the body 1 and perpendicular to the component mounting surface 1c when the pressure sensors 21 and 22 are attached to the body 1.
A sensor element (not shown) is brought into contact with the back side of the wall forming the pressure-sensitive surface 2b1.

  Thus, in this embodiment, the upstream side pressure sensor 21 of the pair of pressure sensors 21 and 22 is attached to the longitudinal center of the component attachment surface 1c of the body 1, and the downstream side pressure sensor 22 is It is made to attach to the other end part of the longitudinal direction in the said component attachment surface 1c.

  More specifically, when the upstream pressure sensor 21 is attached to the body 1, the attachment surface 2a hermetically seals the opening of the recess 1h via the annular seal member SL4, and the inside of the recess 1h. The fluid resistance member 3 is configured to be pressed and clamped between the bottom surface of the recess 1h. Here, when the upstream pressure sensor 21 is attached, the fluid resistance member 3 stacked in a rectangular parallelepiped shape is pressed against the recess 1h, whereby the seal provided at the end of the upstream internal flow path 1a (2). The member SL3 is elastically deformed and a repulsive force is applied to the fluid resistance member 3. For this reason, it will be strongly pressed and clamped between the upstream side pressure sensor 21, and the fluid resistance member 3 is fixed while maintaining the laminated state.

  In this state, the communication path 3c in the fluid resistance member 3 is connected to the pressure introduction port 2a1 of the upstream pressure sensor 21, and the internal flow path 1a (2) upstream of the resistance flow path 3a is connected to the communication path 3c. It is constituted so as to communicate with the upstream pressure sensor 21 via.

  On the other hand, the internal flow path 1a (3) on the downstream side of the resistance flow path 3a extends along the longitudinal direction of the body 1 to reach the fluid outlet 1e, and is further downstream by the branch flow path 1i branched in the middle. The side pressure sensor 22 is connected to the pressure inlet 2a1.

  The control circuit 6 is provided separately from or attached to the body 1 and includes a CPU, a memory, an I / O channel, an A / D converter, a D / A converter, and other analog or digital electric circuits. ing. Then, the CPU and other peripheral devices cooperate with each other in accordance with the program stored in the memory, so that the control circuit 6 controls the flow rate adjusting valve 4 to set the fluid flow rate of the internal flow path 1a from the outside. Adjust the flow rate. Therefore, an outline of the operation will be briefly described below together with the operation of the mass flow controller.

  When the control circuit 6 receives the output signal values from the pressure sensors 21 and 22, the control circuit 6 upstream of the resistance flow path 3 a based on a predetermined conversion formula considering an offset, a coefficient and the like from the output signal values. And the pressure of the fluid on the downstream side is calculated. Based on these pressures and the previously measured fluid resistance value (resistance coefficient) in the resistance channel 3a, fluid viscosity, and the like, the flow rate of the fluid flowing through the resistance channel 3a is calculated.

  On the other hand, when a set flow rate is given from an operator or another external device, the control circuit 6 calculates a deviation between the set flow rate and the calculated flow rate, and the calculated flow rate approaches the set flow rate based on the deviation. Thus, a command signal for expanding and contracting the laminated piezoelectric element 412 is output to the flow control valve 4. In this manner, the separation distance between the valve seat 42a and the valve body 41a is changed, and the flow rate of the fluid flowing through the flow rate adjusting valve 4, that is, the fluid flowing through the internal flow path 1a is adjusted.

  Thus, according to the present embodiment configured as described above, the body 1 is provided with the recess 1h to accommodate the fluid resistance member 3, and the recess 1h can be sealed at once by attaching the pressure sensor 21. Unlike the prior art, it is not necessary to seal the fluid resistance member 3 with a dedicated lid or the like, and it is possible to reduce the number of parts and simplify the assembly, thereby reducing the cost.

  Moreover, since the flow regulating valve 4 and the fluid resistance member 3 are provided side by side on the component mounting surface 1c in the body 1, the volume of the internal flow path 1a connecting between them can be reduced as much as possible. Therefore, the time lag between the detection of the flow rate and the control of the flow rate can be reduced, and the control response of the mass flow controller 100 can be greatly improved.

  Furthermore, since the fluid resistance member 3 and the pressure sensor 21 are disposed in a substantially direct stack, although the seal member is interposed, it is possible to suppress the body 1 from being elongated in the longitudinal direction as much as possible, and to be compact. Can be promoted.

In terms of downsizing, the following effects can also be achieved. That is, the pressure sensors 21 and 22 are configured such that the pressure-sensitive surface 2b1 stands upright with respect to the mounting surface 2a, and the pressure sensors 21 and 22 are viewed in plan view, the fluid flow direction and the pressure-sensitive surface 2b1. Are mounted in series on the body mounting surface 1c so that the pressure-sensitive surface 2b1 has a large area and a high area while maintaining high sensitivity, the size in the width direction is reduced, and the shape is elongated in plan view. it can.
The present invention is not limited to the above embodiment.

  For example, as schematically shown in FIG. 10, the fluid resistance member 3 may be sealed by the downstream pressure sensor 22 in that the advantage of reducing the number of parts can be enjoyed.

  In addition, it is not always necessary to provide a recess for accommodating the fluid resistance member, and the fluid resistance member may be protruded from the component mounting surface and the pressure sensor may be attached thereto. At that time, it is conceivable to provide a recess for accommodating the fluid resistance member on the pressure sensor side.

Furthermore, theoretically, it is possible to provide a flow rate adjusting valve downstream of the pressure sensor. When the downstream pressure or upstream pressure of the mass flow controller is constant, the pressure sensors are not necessarily paired. There is no need to provide it, and only one of them may be provided.
The fluid resistance member may use a sonic nozzle.

  Moreover, in the said embodiment, although the flow measurement mechanism 10 measured a flow based on the differential pressure | voltage of the fluid before and behind the fluid resistance member 3, the said flow measurement mechanism 10 is a thermal flow rate which is a fluid measurement apparatus. A sensor 23 may be provided.

  Hereinafter, a mass flow controller 100 using a thermal flow sensor 23 according to another embodiment of the present invention will be described with reference to a fluid circuit diagram of FIG. 11, an overall perspective view of FIG. 12, and a longitudinal sectional view of FIG. As shown in FIGS. 11 and 12, a thermal flow sensor 23 and a flow rate adjusting valve 4 are provided in this order from the upstream along an internal flow path 1a through which a fluid to be flow controlled. The control circuit 6 controls the flow rate adjusting valve 4 so that the flow rate measured by the thermal flow sensor 23 becomes a predetermined target flow rate.

  The internal flow path 1a is formed in a body 1 having a long and thin rectangular parallelepiped shape as in the above-described embodiment, and the fluid inlet port 1d and the fluid outlet port 13 are opened in a plane orthogonal to the longitudinal direction of the body 1. The fluid flows through the inside in a substantially longitudinal direction. Then, one of the surfaces orthogonal to the surface on which the fluid inlet 1d and the fluid outlet 1e are provided is a component mounting surface 1c, and the thermal flow sensor 23 and the flow rate adjusting valve 4 are mounted on this surface. It is like that. Hereinafter, since the flow rate adjusting valve 4 has the same configuration as that of the embodiment, the description thereof will be omitted, and the flow rate measuring mechanism 10 and the thermal flow rate sensor 23 will be described.

  As shown in FIG. 11, the flow rate measuring mechanism 10 is provided so as to connect the resistance channel 3a provided on the internal channel 1a and the upstream side and the downstream side of the resistance channel 3a in terms of fluid circuit. The flow rate of the fluid is calculated based on the sensor flow path 23a thus obtained, the two coil-shaped sensor parts 234 and 235 wound around the outer pipe of the sensor flow path 23a, and the value output from the sensor part. And a flow rate calculation unit 236. The control circuit 6 controls the opening degree of the subsequent flow rate adjusting valve 4 so that the flow rate value output from the flow rate calculation unit 236 becomes the target flow rate value.

  The thermal flow sensor 23 is attached to the base portion 2A1 for pressing the substantially rectangular fluid resistance member 3 provided in the concave portion 1h of the component mounting surface 1c of the body 1 from above, and to the upper surface of the base portion 2A1. And a sensor accommodating portion 2A2 that accommodates a measuring narrow tube 232 having a particularly small diameter in the sensor flow path 23a and sensor portions 234 and 235 wound around the outer tube of the measuring thin tube 232. is there.

  The base portion 2A1 is a substantially rectangular parallelepiped block body, and the fluid resistance member 3 is sandwiched and held between the base portion 2A1 and the body 1. Therefore, bolt mounting holes are provided at the four corners so as to penetrate the upper surface and the lower surface of the base portion, and bolts are passed from the bolt mounting holes to the threads provided on the component mounting surface 1c side of the body 1. By screwing, the fluid resistance member 3 is pressed against the body 1 and is fixed substantially hermetically by a seal member. In addition, a fluid introduction port 2a1 corresponding to the introduction port in the claims of the sensor flow path is opened at the center of the lower surface of the base portion 2A2, and communicates with the communication passage 3c of the fluid resistance member 3. It is. A fluid introduction channel 231 is provided from the fluid introduction port 2a1 toward the upper surface, passes through a measurement capillary 232 described later, and again from the outlet port 2a2 of the fluid outlet channel 233 provided in the base portion 2A1. It returns to the outer edge of 1h.

  The sensor housing portion 2A2 has a rectangular parallelepiped casing that is attached to the upper surface of the base portion in the vertical direction, and has a substantially inverted U-shaped measurement capillary 232 and an outer tube of the measurement capillary 232 inside. The upstream sensor unit 234 and the downstream sensor unit 235 to be wound are accommodated. In the cross-sectional view, the description of each sensor unit is omitted. Both ends of the measurement thin tube 232 are air-tightly attached to the opening of the flow channel opened on the upper surface of the base portion 2A1 by welding.

  The fluid resistance member 3 is formed by laminating a plurality of thin plates as in the above embodiment, and is configured to function as a so-called laminar flow element by adjusting the size and number of slits of each thin plate. is there. That is, by providing the thermal flow sensor 23 and the fluid resistance member 3 in this way, a part of the fluid that has passed through the upstream internal flow path 1 a (2) of the body 1 is resistant to the resistance of the fluid resistance member 3. The flow passes through the flow path 3a, is stratified and flows to the downstream internal flow path 1a (3), and the rest passes through the communication path 3c and bypasses the measurement flow path 23a to pass the downstream internal flow path. It will flow to 1a (3). At this time, the ratio of the flow rate flowing directly from the upstream internal flow path 1a (2) to the downstream internal flow path 1a (3) and the flow rate flowing through the sensor flow path 23a is a ratio suitable for flow measurement. The flow resistance of the fluid resistance member 3 is set.

  The flow rate measurement will be briefly described. In this embodiment, a so-called constant current type thermal flow rate measurement is performed. In the measurement flow path 23a, the current flowing through the sensor units 234 and 235 is constant. In a controlled state, it is detected that the resistance value of the upstream sensor unit 234 and the downstream sensor unit 235 changes due to heat being transferred by the fluid flowing through the measurement flow path 23a, and the applied voltage changes. By doing so, the flow rate of the fluid is detected.

  As a modified example of the embodiment using this thermal flow sensor, for example, a constant temperature type thermal flow measurement may be performed, or the temperature of the fluid may be measured and the upstream side in the sensor flow path The flow rate may be measured based on the temperature change on the downstream side. Even when other fluid measurement methods are used, a fluid resistance member is provided between the body and a fluid measurement device that measures the physical quantity of the fluid, and the fluid resistance member is pressed by the casing of the fluid measurement device. As long as it is airtightly fixed.

  In addition, the present invention can be variously modified without departing from the spirit of the present invention.

  According to the flow measurement mechanism and the mass flow controller of the present invention, the fluid measuring device and the fluid resistance member are stacked on the same side of the body, so that the internal flow path length between them can be shortened as much as possible. Sensing responsiveness can be improved. Further, since the fluid measuring device is laminated on the fluid resistance member, it is possible to prevent the body from becoming unnecessarily long, and it does not cause a complicated structure or an increase in the number of parts.

DESCRIPTION OF SYMBOLS 100 ... Mass flow controller 10 ... Flow measurement mechanism 1 ... Body 1a ... Internal flow path 1a (2) ... Upstream internal flow path 1a (3) ... Downstream internal flow path 1h ... Recess 1c ... Outer surface (component mounting surface)
21, 22 ... Pressure sensor 23 ... Thermal flow sensor 2a1 ... Pressure inlet, fluid inlet (inlet)
2a2 ... Deriving port 3 ... Fluid resistance member 3a ... Resistance channel 3c ... Communication channel 4 ... Flow rate adjusting valve 6 ... Control circuit

Claims (5)

A body having an internal flow path through which a fluid to be measured flows;
A recess formed by opening on the outer surface of the body so as to divide the internal flow path;
A fluid resistance member housed in the recess;
A fluid measuring device that is attached to the body so as to close an opening of the concave portion to the outer surface of the body and detects a physical quantity related to the flow rate of the fluid to be measured;
The fluid resistance member is configured to be pressed against the body by attaching the casing of the fluid measuring device to the body,
A measuring mechanism, wherein a sensor element of the fluid measuring device is arranged outside the concave portion in a state where the casing of the fluid measuring device is attached to the body.   The measuring mechanism according to claim 1, wherein a surface of the fluid resistance member facing the casing of the fluid measuring device is pressed on the entire surface by attaching the casing of the fluid measuring device to the body. .   The measurement mechanism according to claim 1, wherein the fluid measuring device is a pressure sensor.   The measurement mechanism according to claim 1, wherein the fluid resistance member is a sonic nozzle.   A mass flow controller comprising the measurement mechanism according to claim 1.