Patent Publication Number: US-2023160493-A1

Title: Fluid control valve and fluid control apparatus

Description:
BACKGROUND 
     Technical Field 
     The present invention relates to a fluid control valve and a fluid control apparatus. 
     Related Art 
     As a conventional fluid control valve, there is a control valve used in a mass flow controller, such as that disclosed in JP 2021-514042 A. The control valve includes a valve cavity that has an inlet and an outlet, a poppet valve (valve body) that is disposed inside the valve cavity, that has a plurality of vertical channels, and the bottom surface of which faces the inlet, and an orifice that is disposed between the poppet valve and the outlet inside the valve cavity. The inlet is provided on the bottom surface of the valve cavity, and the outlet is provided on the inner circumferential surface of the valve cavity. 
     To achieve a high flow rate, the orifice has a plurality of vertical channels extending from the bottom surface (valve seat surface) to the top surface, and a plurality of horizontal channels opening to an outer circumference of the orifice. Each of the horizontal channels intersects with at least one of the vertical channels in the orifice. As the poppet valve moves away from the bottom surface (valve seat surface) of the orifice, the gas rises from the bottom surface of the orifice through the vertical channels, then horizontally advances through horizontal channels or along a surface channel provided on the top surface of the orifice, and flows out to the outlet. 
     However, in the above configuration, the gas risen through the vertical channels rarely flows into the horizontal channels, and tend to just cross the horizontal channels and to flow to the top surface of the orifice. This might cause a deterioration of responsiveness in the flow rate. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: JP 2021-514042 A 
     SUMMARY 
     Therefore, the present invention has been made in consideration of the problem described above, and a main object of the present invention is to improve the responsiveness in the flow rate, while increasing the flow rate. 
     Solution to Problem 
     In other words, a fluid control valve according to the present invention is characterized in including: an orifice having a valve seat surface; a valve body having a seating surface on which the valve seat surface is seated; a driving unit configured to drive the valve body; a channel block provided with a housing recess for housing the orifice and the valve body, wherein the orifice includes: a vertical channel that opens to the valve seat surface and to a facing surface facing the valve seat surface; and a horizontal channel that opens to an outer circumferential surface between the valve seat surface and the facing surface, and that intersects with the vertical channel, and the vertical channel is split into a plurality of branch channels with a space therebetween, on a side of the facing surface, from an intersection with the horizontal channel. 
     With such a fluid control valve, because the horizontal channel and the vertical channel are configured to intersect with each other, it is possible to increase the flow rate, compared with an example that uses only the vertical holes. In addition, because the vertical channel is split into a plurality of branch channels with a space therebetween, on the side of the facing surface, from the intersection with the horizontal channel, the inner wall surface defining the horizontal channel extends between the branch channels. As a result, the fluid risen along the vertical channels hits the inner wall surface of the horizontal channel, the inner wall extending between the branch channels, so that the fluid can flow into the horizontal channel more easily. Hence, the responsiveness of the flow rate can be improved. Therefore, according to the present invention, it is possible to improve the responsiveness of the flow rate, while increasing the flow rate. In addition, because the vertical channel is split into a plurality of branch channels from the intersection with the horizontal channel, the fluid flowing out from the facing surface can be distributed uniformly. 
     As a specific embodiment of the vertical channels, the vertical channel has two branch channels on the side of the facing surface with respect to the intersection, and the center axes of the two respective branch channels are not in line with the center axis of the horizontal channel, preferably. Specifically, in a plan view, two branch channels are arranged in a direction orthogonal to the central axis of the horizontal channel. 
     In order to increase the flow rate flowing into the vertical channel and to make it easier for the fluid to flow into the horizontal channel, the opening width of the vertical channel on the side of the valve seat with respect to the intersection is larger than the channel diameter of the horizontal channel, preferably. 
     In order to further increase the flow rate using the fluid control valve of the present invention, the vertical channel is provided in plurality, and the horizontal channel is provided in plurality, preferably. 
     In a configuration in which all of the vertical channels intersect with the horizontal channels, the number of the vertical channels is restricted by the number of the horizontal channels, so that it is not possible to achieve an even higher flow rate. In order to suitably solve this problem and to achieve a higher flow rate, at least one of the plurality of vertical channels intersects with none of the horizontal channels, preferably. 
     In order to allow the fluid passed through the vertical channels and flown out of the facing surface to merge with the fluid passed through the horizontal channel and flown out of the outer circumferential surface, the facing surface is preferably provided with a cutout that extends radially outwards from an opening of the vertical channel. 
     In the fluid control valve according to the present invention, the plunger provided to the driving unit for driving the valve body is inserted into the center of the orifice. As a specific embodiment of this configuration, the vertical channel may be provided in plurality along a circumferential direction, and a central channel opening to the valve seat surface and the facing surface may be provided at a center of the circumferential direction. In this configuration, a plunger is inserted into the central channel. 
     In this configuration, the diameter of the central channel preferably increases continuously from the side of the valve seat surface toward the side of the facing surface. With this configuration, a pressure loss of the fluid flowing through the central channel can be reduced, so that the flow rate can be increased further. 
     It is preferable that: an upstream channel is connected to a bottom surface of the housing recess, and a downstream channel is connected to an inner circumferential surface of the housing recess; and that an annular recess is provided on the inner circumferential surface of the housing recess correspondingly to an opening of the horizontal channel. 
     With this configuration, the annular recess formed on the inner circumferential surface of the housing recess can increase the size of the channel for the fluid flowing out of the horizontal channel, so that it becomes possible to reduce the pressure loss and to increase the flow rate. 
     A fluid control apparatus including the fluid control valve is also an aspect of the present invention. Specifically, the fluid control apparatus includes the fluid control valve, a flowmeter unit configured to measure a flow rate in the channel, and a control unit configured to control the fluid control valve based on a measurement collected by the flowmeter unit. 
     Advantageous Effects of Invention 
     According to the present invention described above, because the vertical channel branches off from the intersection with the horizontal channel at an interval on the facing surface side, it is possible to improve the responsiveness while increasing the flow rate. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a cross-sectional view schematically illustrating a configuration of a fluid control apparatus according to one embodiment of the present invention; 
         FIG.  2    is a partially enlarged cross-sectional view illustrating an orifice and a valve body included in a fluid control valve according to the embodiment; 
         FIG.  3    is a perspective view of an orifice according to the embodiment; 
         FIG.  4    is a plan view of the orifice according to the embodiment; 
         FIG.  5    is a bottom view of the orifice according to the embodiment; 
         FIG.  6    is a plan view of and a cross-sectional view across the line A-A in the orifice according to the embodiment; 
         FIG.  7    is a plan view of and a cross-sectional view across the line B-B in the orifice according to the embodiment; 
         FIG.  8    is a plan view of and a cross-sectional view across the line C-C in the orifice according to the embodiment; 
         FIG.  9    is a plan view of and a cross-sectional view across the line D-D in the orifice according to the embodiment; and 
         FIG.  10    is a schematic diagram illustrating a configuration of a fluid control apparatus according to a modification of the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A fluid control apparatus according to an embodiment of the present invention will now be explained with reference to some drawings. Note that, to facilitate understanding, all of the drawings described below are schematic representations, with some omissions and exaggerations made as appropriate. The same components are denoted by the same reference numerals, and the descriptions thereof will be omitted as appropriate. 
     Device Configuration 
     A fluid control apparatus  100  according to the present embodiment is what is called a mass flow controller, and is used in controlling a flow rate of gas supplied into a chamber where semiconductor manufacturing processing is performed, for example. The fluid control apparatus  100  may control not only gas but also liquid. 
     Specifically, as illustrated in  FIG.  1   , the fluid control apparatus  100  includes a channel block  2  internal of which is provided with a channel R, a fluid control valve  3  for controlling the gas inside the channel R, a flowmeter unit  4  for measuring the flow rate in the channel R, and a control unit  5  for controlling the fluid control valve  3  based on the measurement collected by the flowmeter unit  4 . 
     The channel block  2  is provided with a housing recess  21  where the fluid control valve  3  is installed. The housing recess  21  is provided on one surface (top surface in  FIG.  1   ) of the channel block  2 . An upstream channel R 1  is connected to the bottom surface of the housing recess  21 , and a downstream channel R 2  is connected to the inner circumferential surface of the housing recess  21 . In other words, the channel R provided inside the channel block  2  is divided into the upstream channel R 1  and the downstream channel R 2  by the housing recess  21 . 
     A gas entry port (not illustrated) is provided on an upstream end of the upstream channel R 1 , and a gas discharge port (not illustrated) is provided on a downstream end of the downstream channel R 2 . 
     The fluid control valve  3  is what is called a normally-closed piezoelectric valve, and the degree by which the fluid control valve  3  is opened is controlled by a voltage applied thereto. The fluid control valve  3  may be what is called a normally-opened piezoelectric valve. 
     Specifically, as illustrated in  FIGS.  1  and  2   , the fluid control valve  3  includes an orifice (valve seat member)  31  having a valve seat surface  31   s,  a valve body  32  having a seating surface  32   s  seated on the valve seat surface  31   s,  and a driving unit  33  that drives the valve body  32 . 
     The orifice  31  is housed in the housing recess  21 . At this time, the orifice  31  is housed in the housing recess  21  in such a manner that the valve seat surface  31   s  faces the bottom surface of the housing recess  21 . In the orifice  31 , an inlet is provided to the valve seat surface  31   s,  and an internal channel  31 R communicating with the inlet is also provided. The orifice  31  will be explained later in detail. 
     The valve body  32  is provided movably inside the housing recess  21 . Inside the housing recess  21 , the valve body  32  is provided between the valve seat surface  31   s  of the orifice  31  and the bottom surface of the housing recess  21 . 
     Specifically, the valve body  32  has the seating surface  32   s  on the top surface, and an outlet as well as an internal channel  32 R communicating with the outlet are provided on the seating surface  32   s.  The outlet on the seating surface  32   s  and the inlet on the valve seat surface  31   s  are formed at positions not overlapping each other when the seating surface  32   s  is seated on the valve seat surface  31   s.    
     Inside the housing recess  21 , the valve body  32  is supported movably by the support member  34 . The support member  34  includes a support base  341  having an annular shape and housed inside the housing recess  21 , and an elastic body  342 , such as a leaf spring, provided inside the support base  341  to support the valve body  32 . As a result, the valve body  32  is supported by the elastic body  342 , inside the support base  341 . Note that both of the support base  341  and the elastic body  342  are configured to permit a gas flow. In addition, the bottom surface of the orifice  31  is in close contact with the annular-shaped top surface of the support base  341 , together forming a valve chamber  51  where the valve body  32  is housed, and that communicates with the upstream channel R 1 . 
     The driving unit  33  includes, for example, a piezoelectric stack  331  formed by stacking a plurality of piezoelectric elements, and a plunger mechanism  332  that becomes displaced by extension of the piezoelectric stack  331 . 
     The piezoelectric stack  331  is housed inside a casing  333 , and has an end connected to the plunger mechanism  332 . The plunger mechanism  332  according to the present embodiment includes a diaphragm member  332   a,  and a pressing member  332   b  that presses the top surface of the valve body  32  with the diaphragm member  332   a  therebetween. The plunger mechanism  332  is inserted into the central channel CR of the orifice  31 , and is brought into contact with the top surface of the valve body  32 . 
     When a predetermined voltage is applied to the piezoelectric stack  331 , the piezoelectric stack  331  is caused to extend, and the plunger mechanism  332  applies a biasing force to the valve body  32  in the direction in which the valve opens, and the valve seat surface  31   s  becomes separated from the seating surface  32   s  by a distance corresponding to the applied voltage, and becomes opened. The upstream channel R 1  and the downstream channel R 2  come to communicate with each other via this gap. During the normal condition without any application of the voltage to the piezoelectric stack  331 , the valve body  32  is kept closed by the elastic force of the elastic body  342  of the support member  34 . 
     The flowmeter unit  4  is a flowmeter of a type that uses pressure, and includes a laminar flow element  41  provided in the channel R, a first pressure sensor  42  provided so as to be able to measure the pressure on the upstream side of the laminar flow element  41 , a second pressure sensor  43  provided so as to be able to measure the pressure on the downstream side of the laminar flow element  41 , and a flow rate calculator unit  44  that calculates the flow rate of the fluid flowing through the channel R based on the first pressure and the second pressure measured by the first pressure sensor  42  and the second pressure sensor  43 , respectively. The flowmeter unit  4  is provided either upstream or downstream of the fluid control valve  3  in the channel R. As a fluid resistance  41 , a sonic nozzle or the like may be used, instead of the laminar flow element. 
     The control unit  5  controls the fluid control valve  3  based on the flow rate measurement collected by the flowmeter unit  4 . The control unit  5  is a computer including a CPU, a memory, an A/D converter, a D/A converter, and various input/output units, and controls the fluid control valve  3  by executing a fluid control program stored in the memory, and causing the CPU and peripheral devices to cooperate with one another. 
     The control unit  5  controls the degree by which the fluid control valve  3  is opened, based on a command flow rate input from outside, and on the flow rate measurement collected by the flowmeter unit  4 . Specifically, the control unit  5  controls the degree by which the fluid control valve  3  is opened so that a deviation between the command flow rate and the flow rate measurement is reduced. The control unit  5  according to the present embodiment performs PID calculation on the deviation between the command flow rate and the flow rate measurement, and outputs a command voltage corresponding to the result to the driving circuit of the driving unit  33 . The driving circuit applies a voltage corresponding to the input command voltage to the piezoelectric stack  331 . 
     Specific Configuration of Orifice  31   
     The orifice  31  according to the present embodiment has a configuration for increasing the flow rate and improving the responsiveness of the flow rate. 
     Specifically, as illustrated in  FIGS.  2  to  9   , the orifice  31  has a substantially disk-like shape, and includes, as the internal channel  31 R, a plurality of vertical channels VR (VR 1 , VR 2 ) opening to the valve seat surface  31   s  and to a facing surface  31   t  facing the valve seat surface  31   s , and a plurality of horizontal channel HR opening to the outer circumferential surface  310  that extends between the valve seat surface  31   s  and the facing surface  31   t,  and intersecting with the vertical channels VR. 
     In the orifice  31  according to the present embodiment, a plurality of vertical channels VR (VR 1 , VR 2 ) are arranged in a circumferential direction (see  FIGS.  3  and  4   ), and the central channel CR opening to the valve seat surface  31   s  and to the facing surface  31   t  is provided at the center of the circumferential direction (see  FIGS.  6  to  8   , for example). The central channel CR is a channel through which the plunger mechanism  332  included in the driving unit  33  is inserted (see  FIG.  2   ). The central channel CR has a diameter increasing continuously from the side of the valve seat surface  31   s  toward the facing surface  31   t.  With this configuration, the pressure loss of the gas flowing through the central channel CR can be reduced, so that the flow rate can be increased. 
     As illustrated in  FIGS.  3  and  6  to  8   , the horizontal channel HR open to the outer circumferential surface  310  of the orifice  31 , and also open to the inner circumferential surface  31   i  delineating the central channel CR. In the present embodiment, four horizontal channel HR are provided radially (see  FIGS.  4  and  5   ). Each of the horizontal channels HR has a linear shape, and a channel cross-section shape thereof is circular (see  FIG.  6   , for example). 
     As illustrated in  FIGS.  3  to  5   , for example, the vertical channels VR include first vertical channels VR 1  that intersect with and communicate with the horizontal channels HR, and second vertical channels VR 2  not intersecting with the horizontal channel HR. The second vertical channels VR 2  are channels that are formed between the adjacent horizontal channel HR, and are not split into branch channels (see  FIG.  8   ). 
     Specifically, as illustrated in  FIG.  9   , each of the first vertical channels VR 1  is split on the side of the facing surface  31   t,  into two branch channels VR 11  and VR 12  with a space therebetween, from an intersection X with the horizontal channel HR. In other words, the first vertical channel VR 1  is one channel on the side of the valve seat surface  31   s  with respect to the intersection X with the horizontal channel HR, and includes two channels on the side of the facing surface  31   t  with respect to the intersection X with the horizontal channel HR. 
     The central axes C 11  and C 12  of the respective two branch channels VR 11  and VR 12  are not in line with the central axis C 2  of the horizontal channel HR. In other words, in a plan view, the two branch channels VR 11 , VR 12  are arranged side by side in a direction orthogonal to the central axis C 2  of the horizontal channel HR. The central axes C 11  and C 12  of the two respective branch channels VR 11  and VR 12  extend in parallel with each other. With this configuration, an inner wall surface  31   k,  which defines the horizontal channel HR, extends between the two branch channels VR 11  and VR 12 , and this inner wall surface  31   k  is configured to provide a partition between the two branch channels VR 11  and VR 12 . Furthermore, by splitting each of the vertical channels VR 1  into branches, the mechanical strength of the orifice  31  can be ensured. 
     Furthermore, the opening width (channel width) of the first vertical channel VR 1  on the side of the valve seat surface  31   s  with respect to the intersection X is configured to be larger than the channel diameter of the horizontal channel HR (see  FIG.  9   ). With this configuration, the flow rate of the gas flowing into the first vertical channel VR 1  is increased so that the gas easily flows into the horizontal channel HR. The opening width (channel width) represents, on the side of the valve seat surface  31   s,  the distance between the farthest points on the inner wall surfaces of the two branch channels VR 11  and VR 12 , respectively. 
     In the present embodiment, as illustrated in  FIG.  5   , an annular groove  31 M is provided, on the valve seat surface  31   s  of the orifice  31 , in a manner following the vertical channels VR (VR 1 , VR 2 ) that are arranged along the circumferential direction. The annular groove  31 M allows the vertical channels VR (VR 1 , VR 2 ) to communicate with one another, and the annular groove  31 M serves as a part of the vertical channels VR (VR 1 , VR 2 ). In other words, the opening of the annular groove  31 M on the side of the valve seat surface  31   s  serves as the inlet formed on the valve seat surface  31   s.  With this configuration, the size of the inlet of the internal channel  31 R, the inlet being provided on the valve seat surface  31   s,  is increased so that it becomes possible to achieve a high flow rate. 
     As illustrated in  FIGS.  3  and  4   , for example, the facing surface  31   t  of the orifice  31  is provided with cutouts  31 K extending radially outwards from the openings of the respective vertical channels VR. In the present embodiment, these cutouts  31 K are provided correspondingly to the openings of the second vertical channels VR 2  that do not intersect with the horizontal channel HR. Through these cutouts  31 K, the gas flowing through the vertical channels VR and the central channel CR, and flowing out of the facing surface  31   t  flows into the side of the outer circumferential surface  31   o  of the orifice  31 , and flows into the downstream channel R 2  that is connected to the inner circumferential surface of the housing recess  21 . The cutouts  31 K make it easy for the gas having flown through the first and second vertical channels VR 1  and VR 2  and out from the facing surface  31   t  to become merged with the gas having flown through the horizontal channels HR and out from the outer circumferential surface  31   o.    
     At this time, as illustrated in  FIG.  2   , an annular recess  21 M is provided on the inner circumferential surface of the housing recess  21  correspondingly to the openings of the horizontal channels HR. With this configuration, the annular recess  21 M provided on the inner circumferential surface of the housing recess  21  can increase the size of the channel for the gas flowing out of the horizontal channels HR, so that it becomes possible to increase the flow rate by reducing the pressure loss. In addition, as illustrated in  FIG.  3   , for example, a recess  31 N is also provided across the entire outer circumferential surface  310  of the orifice  31 . The cutouts  31 K communicate with the recess  31 N. The horizontal channels HR open onto the bottom surface of the recess  31 N. The recess  31 N further increases the size of the channel between annular recess  21 M of the housing recess  21  and the annular groove  31 M, so that it becomes possible to increase the flow rate by reducing the pressure loss. 
     One example of a method of manufacturing the orifice  31  will now be explained. 
     To begin with, the central channel CR is formed, by machining such as cutting, at the center of the disk-shaped base material. The horizontal channels HR are also formed, by machining such as cutting, in a manner opening to the outer circumferential surface  310  of the base material, and to the inner circumferential surface  31   i  of the central channel CR. 
     The annular groove  31 M is then formed, by machining such as cutting, on the surface that is to be the valve seat surface  31   s  of the base material. At this time, the depth of the annular groove  31 M is set to a depth communicating with the horizontal channel HR. The annular groove  31 M provides a part of the first vertical channels VR 1  and the second vertical channels VR 2 . 
     The two branch channels VR 11  and VR 12  of the first vertical channels VR 1  are then formed by machining such as cutting, on both sides of the central axis C 2  of the horizontal channel HR, from the surface to be the facing surface  31   t  of the base material. The branch channels VR 11  and VR 12  are formed in a manner communicating with the horizontal channels HR. 
     The second vertical channels VR 2  are also formed by machining such as cutting, at positions not intersecting with the horizontal channels HR, from the surface to be the facing surface  31   t  of the base material. The second vertical channels VR 2  are formed in a manner communicating with the annular groove  31 M. The other structures of the orifice  31  described above are also formed by machining such as cutting. The orifice  31  is manufactured in the manner described above. 
     Advantageous Effects of Present Embodiment 
     In the fluid control apparatus  100  configured as described above, because the horizontal channels HR intersect with the first vertical channels VR 1 , it is possible to increase the flow rate. In addition, because each of the vertical channels VR is split into branch channels with a space therebetween, from the intersection X with the horizontal channel HR, on the side of the facing surface  31   t,  the inner wall surface  31   k  defining the horizontal channel HR extends between the branch channels VR 11  and VR 12 . As a result, the gas risen through the first vertical channel VR 1  hits the inner wall surface  31   k  defining the horizontal channel HR and extending between the branch channels VR 11  and VR 12 , so that the gas can flow into the horizontal channel HR more easily, and therefore, the responsiveness of the flow rate can be improved. In addition, it is also possible to increase the flow rate by increasing the size of the inlets of the first vertical channels VR 1 . Therefore, according to the present embodiment, the responsiveness of the flow rate can be improved while increasing the flow rate. In addition, because each of the vertical channels VR is split into branch channels from the intersection X with the horizontal channel HR, the gas flowing out from the facing surface  31   t  can be distributed uniformly. In particular, in the present embodiment, because the outlets of the two branch channels VR 11  and VR 12  of each of the first vertical channels VR 1 , and the outlets of the second vertical channels VR 2  are arranged along the circumferential direction, the gas flowing out of the facing surface  31   t  can be distributed more uniformly. 
     Other Embodiments 
     For example, while some of the vertical channels VR do not intersect with the horizontal channels HR in the above embodiment, all the vertical channels VR may be configured to intersect with the horizontal channels HR. 
     Furthermore, in the above embodiment, every one of the vertical channels VR intersecting with the horizontal channel HR is split into branch channels from the intersection X, but it is possible to configure some of the vertical channels VR intersecting with the horizontal channel HR not split into branch channels from the intersection X. 
     Furthermore, the number of the horizontal channels HR is not limited to that according to the embodiment described above, and may also be any one of one to three or five or more. 
     In addition, the orifice  31  according to the embodiment described above is an example in which the inlets are provided along one circumferential direction, but it is also possible for the inlets to be provided along a plurality of circumferential directions that are concentrically arranged. 
     The flowmeter unit  4  according to the embodiment described above is of a pressure-based flowmeter, but may also be a thermal flowmeter. Specifically, as illustrated in  FIG.  10   , the thermal flowmeter unit  4  includes a shunt element (resistance element)  45  provided to the channel R, a narrow tube  46  that is branched from the channel R on an upstream side of the shunt element  45  and that is merged to the channel R on a downstream side of the shunt element  45 , two electric heating coils  47  that are wound around the narrow tube  46  and that are kept at a constant temperature, by receiving applications of voltages, respectively, and a flow rate calculator unit  48  that detects a difference between the voltages applied to the respective electric heating coils  47  and that calculates a flow rate of the gas flowing through the channel R. The flowmeter unit  4  is provided either upstream or downstream of the fluid control valve  3  in the channel R. Note that the principle of flow rate measurement in the flowmeter unit is not limited to that described above, and any method may be used. 
     In addition, various modifications and combinations of the embodiments may be made within the scope not deviating from the gist of the present invention. 
     DESCRIPTION OF REFERENCE CHARACTERS 
       100  fluid control apparatus 
       2  channel block 
       21  housing recess 
     R 1  upstream channel 
     R 2  downstream channel 
       21 M annular recess 
       3  fluid control valve 
       31  orifice 
       31   s  valve seat surface 
       31   t  facing surface 
     CR central channel 
     VR vertical channel 
     VR 1  first vertical channel 
     VR 2  second vertical channel 
     HR horizontal channel 
     X intersection 
     VR 11  branch channel 
     VR 12  branch channel 
     C 11  center axis of branch channel 
     C 12  center axis of branch channel 
     C 2  central axis of horizontal channel 
       31 K cutout 
       32   s  seating surface 
       32  valve body 
       33  driving unit