Patent Publication Number: US-2021172780-A1

Title: Flowmeter

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is a continuation application of International Patent Application No. PCT/JP2019/022339 filed on Jun. 5, 2019, which designated the U.S. and claims the benefit of priority from Japanese Patent Application No. 2018-157230 filed on Aug. 24, 2018. The entire disclosures of all of the above applications are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a flowmeter. 
     BACKGROUND ART 
     A flowmeter is disposed in a passage through which a fluid flows and configured to measure a flow rate of the fluid flowing through the passage. The flowmeter includes a first passage defining an opening through which at least a part of the fluid flows into the flowmeter from the passage and a second passage that branches off from the first passage and includes a flow rate detector configured to detect a flow rate of the fluid flowing through the second passage from the first passage. 
     SUMMARY 
     A flowmeter is disposed in a passage through which a fluid flows. The flowmeter includes a first passage that defines a first opening through which at least a part of the fluid flows into the flowmeter from the passage and a second passage that branches off from the first passage and includes a flow rate detector configured to detect a flow rate of the fluid flowing through the second passage from the first passage. The first passage includes therein a vortex reducer configured to restrict a vortex from generating. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cross-sectional view of a flowmeter of a first embodiment. 
         FIG. 2  is a schematic view of the flowmeter viewed in a −Y direction. 
         FIG. 3  is a cross-sectional view of the flowmeter of the first embodiment. 
         FIG. 4  is a cross-sectional view of a flowmeter of a comparative example. 
         FIG. 5  is a cross-sectional view of a flowmeter of a second embodiment. 
         FIG. 6  is a cross-sectional view of the flowmeter of the second embodiment. 
         FIG. 7  is a cross-sectional view of a flowmeter of a third embodiment. 
         FIG. 8  is a cross-sectional view of a flowmeter of another embodiment. 
         FIG. 9  is a cross-sectional view of a flowmeter of another embodiment. 
         FIG. 10  is a schematic view of a flowmeter of another embodiment. 
         FIG. 11  is a schematic view of a flowmeter of another embodiment. 
         FIG. 12  is a cross-sectional view of a flowmeter of another embodiment. 
         FIG. 13  is a schematic view of a flowmeter of another embodiment. 
         FIG. 14  is a cross-sectional view of a flowmeter of another embodiment. 
         FIG. 15  is a cross-sectional view of a flowmeter of another embodiment. 
         FIG. 16  is a cross-sectional view of a flowmeter of another embodiment. 
         FIG. 17  is a cross-sectional view of a flowmeter of another embodiment. 
         FIG. 18  is a cross-sectional view of a flowmeter of another embodiment. 
         FIG. 19  is a cross-sectional view of a flowmeter of another embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     To begin with, examples of relevant techniques will be described. 
     A flowmeter is disposed in a passage through which a fluid flows and configured to measure a flow rate of the fluid flowing through the passage. The flowmeter includes a first passage defining an opening through which at least a part of the fluid flowing into the flowmeter from the passage and a second passage that branches off from the first passage and includes a flow rate detector configured to detect a flow rate of the fluid flowing through the second passage from the first passage. 
     When a flow rate of the fluid flowing into the first passage is uneven around an opening edge of the opening in such flowmeter, a vortex may be formed in the first passage. The generation of the vortex restricts the fluid from flowing into the second passage, which deteriorates an accuracy of the flow rate detector. Thus, a technique to restrict generation of vortices in the first passage of the flowmeter is needed. 
     According to an aspect of the present disclosure, a flowmeter is provided. The flowmeter is disposed in a passage through which a fluid flows. The flowmeter includes a first passage that defines a first opening through which at least a part of the fluid flows into the flowmeter from the passage and a second passage that branches off from the first passage and includes a flow rate detector configured to detect a flow rate of the fluid flowing through the second passage from the first passage. The first passage includes therein a vortex reducer configured to restrict a vortex from generating. According to such flowmeter, a vortex is restricted from generating in the first passage. Therefore, an accuracy of the flow rate detector is restricted from deteriorating, which is caused by restricting the fluid from flowing into the second passage. 
     A. First Embodiment 
     A flowmeter  10  shown in  FIG. 1  is disposed in a passage through which a fluid flows and configured to detect a flow rate of the fluid flowing through the passage. In this embodiment, the flowmeter  10  is inserted into an intake pipe IP that guides the fluid to flow toward a cylinder of an internal combustion engine. XYZ axes in  FIG. 1  are spatial axes perpendicular to each other. The XYZ axes in  FIG. 1  correspond to XYZ axes in other drawings.  FIG. 1  is a cross-sectional view of the flowmeter  10  taken along a YZ plane. Regarding a flow direction of the fluid in  FIG. 1 , a forward direction is a +Y direction and a backward direction is a −Y direction. The forward direction of the flow of the fluid is shown by a direction FD in  FIG. 1 . The cylinder of the internal combustion engine is disposed on a +Y side of the flowmeter  10  in  FIG. 1 .  FIG. 2  is a side view of the flowmeter  10  viewed from a −Y side of the flowmeter  10 .  FIG. 1  is a cross-sectional view viewed in a direction of arrows I in  FIG. 2 .  FIG. 3  is a cross-sectional view of the flowmeter  10  taken along a XY plane.  FIG. 3  is a cross-sectional view viewed in a direction of arrows III in  FIG. 1 . The flowmeter  10  includes a first passage  100 , a second passage  200 , a flow rate detector  300 , a plate member  402 , and a plate member  404 . 
     The first passage  100  is a passage into which a part of the fluid flowing through the intake pipe IP flows. The first passage  100  defines a first opening  100  on a −Y side of the first passage  100  and a second opening  120  on a +Y side of the first passage  100 . The first passage  100  extends from the first opening  110  to the second opening  120 . The flowmeter  10  has a part inserted into the intake pipe IP and a length L 1  between the first opening  110  and a +Z side end of the part is longer than a length L 2  between the first opening  110  and a −Z side end of the part. 
     The second passage  200  branches off from the first passage  100  and extends to the third openings  220 . One of the third openings  220  opens in a wall surface located on the +X side of the flowmeter  10 . The other one of the third openings  220  opens in a wall surface located on the −X side of the flowmeter  10  (not shown in  FIG. 1 ). 
     The flow rate detector  300  is located on a +Z side of the second passage  200 . The flow rate detector  300  is configured to detect a flow rate of the fluid flowing through the second passage  200  from the first passage  100 . In the cross-sectional view in  FIG. 1 , the flow rate detector  300  is located on a far side (i.e., +X side) of a plane of paper, thus the flow rate detector  300  is shown by dashed lines. In this embodiment, the flow rate detector  300  is a hot-wire type flow rate detector. The flow rate detector  300  may be a flap type or a Karman vortex type flow rate detector. 
     The plate member  402  and the plate member  404  are located inside the first passage  100 . Both of the plate member  402  and the plate member  404  extend in the Y direction. The plate member  402  is located on a −Z side of the plate member  404 . In this embodiment, a part of the plate member  402  and a part of the plate member  404  exists within an area R surrounded by a dashed line. The second passage  200  has an opening CS at which the second passage  200  branches off from the first passage  100 . The area R is defined by the opening CS, a normal line plane NL vertically extending from an edge of the opening CS, and an inner surface of the first passage  100 . In other words, the area R is defined by projecting the opening CS along a normal vector of the opening CS. Each of the plate member  402  and the plate member  404  has a −Y side end located at a −Y side end of the first passage  100 . 
     As shown in  FIG. 2 , each of a length of the plate member  402  and the plate member  404  in the X direction is set such that the plate members  402  and  404  cross the first passage  100  in the X direction. Both of the plate member  402  and the plate member  404  are connected to a part of the inner surface located on a +X side of the first passage  100  and a part of the inner surface located on the −X side of the first passage  100 . 
     In the flowmeter  10 , the plate member  402  and the plate member  404  are located inside the first passage  100 , so that a vortex is less likely to be generated in the first passage  100 . A generation of vortices will be described with reference to  FIG. 4 . 
     A flowmeter  10   p  of a comparative example shown in  FIG. 4  is different from the flowmeter  10  of this embodiment in that the flowmeter  10   p  does not include the plate member  402  and the plate member  404 . The same reference numerals as in the first embodiment donate the same structural components, and reference is made to the preceding description. 
     In the flowmeter  10   p  of the comparative example, when a part of the fluid flowing through the intake pipe IP in the +Y direction (i.e., the forward direction) flows into the first passage  100 , a flow UF and a flow DF are generated around an edge of the first opening  110 . The flow UF is a flow of the fluid reflected at a part of the flowmeter  10   p  on a +Z side of the first opening  110  and flowing into the first passage  100 . The flow DF is a flow of the fluid reflected at a part of the flowmeter  10   p  on a −Z side of the first opening  110  and flowing into the first passage  100 . 
     Similarly to the flowmeter  10  of the first embodiment, the length L 1  is longer than the length L 2  in the flowmeter  10   p  of the comparative example. Thus, an amount of the fluid reflecting at a part of the flowmeter  10   p  on a +Z side of the first opening  110  and changing its direction is larger than an amount of the fluid reflected at a part of the flowmeter  10   p  on a +Z side of the first opening  110  and changing its direction. As a result, the flow DF is more likely to be faster than the flow UF. Thus, a flow rate of the fluid flowing into the first passage  100  is biased at the edge of the first opening  110 , so that a vortex VT is sometimes generated in the first passage  100 . The vortex VT restricts the fluid from flowing into the second passage  200  and deteriorates a detecting accuracy of the flow rate detector  300 . 
     In contrast, also in the flowmeter  10  of the first embodiment shown in  FIG. 1 , when a part of the fluid flowing through the intake pipe IP in the Y direction (i.e., the forward direction) flows into the first passage  100 , a flow UF, a flow MF, and a flow DF are generated in the edge of the first opening  110 . The flow MF is a flow of the fluid flowing to a center of the first opening  110  in the Y direction into the first passage  100 . The flow UF and the flow DF are the same as the flow UF and the flow DF in  FIG. 4 . The flowmeter  10  of the first embodiment includes the plate member  402  and the plate member  404  inside the first passage  100  as a vortex reducer that reduces vortices. Thus, the vortex VT explained in the flowmeter  10   p  of the comparative example is less likely to be generated. Thus, a deterioration of the accuracy of the flow rate detector  300 , which occurs when the fluid is restricted from flowing into the second passage  200 , can be restricted. 
     Since the flowmeter  10  of the first embodiment includes the plate member  402  and the plate member  404  within the area R shown in  FIG. 1 , the vortex VT is restricted from generating in the area R. 
     B. Second Embodiment 
     As shown in  FIG. 5 , a flowmeter  12  of a second embodiment differs from the flowmeter  10  of the first embodiment in that the flowmeter  12  does not include the plate member  402  and the plate member  404  and includes a protrusion  502 . Other configurations are similar to those of the first embodiment. The same reference numerals as in the first embodiment denote the same structural components, and reference is made to the preceding description. 
     The flowmeter  12  includes the protrusion  502 . The protrusion  502  protrudes outward from the edge of the first opening  110  in the −Y direction. In this embodiment, the protrusion  502  protrudes from a portion of the edge of the first opening  110  on a +Z side of the first opening  110 . 
       FIG. 6  is a cross-sectional view of the flowmeter  12  taken along a XY plane. The cross-sectional view of the flowmeter  12  in  FIG. 6  is viewed along arrows VI in  FIG. 5 . The protrusion  502  has a rectangular shape when viewed from a −Z side of the protrusion  502 . 
     Also in the flowmeter  12  of the second embodiment, when a part of the fluid flowing through the intake pipe IP in the Y direction (i.e., the forward direction) flows into the first passage  100 , the flow UF and the flow DF are generated around the edge of the first opening  110 . Since the flowmeter  12  of the second embodiment includes the protrusion  502 , the fluid is reflected at the protrusion  502  (i.e., a portion located on the +Z side of the first opening  110 ) and changes its direction. As a result, an amount of the fluid flowing into the first opening is limited. Thus, a difference between a rate of the flow UF and a rate of the flow DF can be decreased compared to the flowmeter  10   p  of the comparative example in  FIG. 4  and the flow rate of the fluid flowing into the first passage  100  is restricted from being biased at the edge of the first opening  110 . Therefore, vortices VT are less likely to be generated in the first passage  100  and the deterioration of the accuracy of the flow rate detector  300 , which occurs when the fluid is restricted from flowing into the second passage  200 , can be restricted. 
     C. Third Embodiment 
     As shown in  FIG. 7 , a flowmeter  14  of a third embodiment differs from the flowmeter  12  of the second embodiment in that the flowmeter  14  includes a plate member  408  and a first passage  100   a  that has a different shape from the first passage  100 . In addition, a shape of a portion of the second passage  200  near a branching position of the second passage  200  branching off from the first passage  100   a  is different from that of the second embodiment. Other configurations are similar to the flowmeter  12  of the second embodiment. The same reference numerals as in the first embodiment denote the same structural components, and reference is made to the preceding description. 
     The flowmeter  14  of the third embodiment includes the first passage  100   a  including a front passage  100   f  and a rear passage  100   g . The front passage  100   f  is a passage between the first opening  110  and a branching position BP at which the second passage  200  branches off from the first passage  100   a . The rear passage  100   g  is a passage between the second opening  120  and the front passage  100   f . The rear passage  100   g  is tilted relative to the front passage  100   f  toward the second passage  200 . In other words, the front passage  100   f  extends in the Y direction and the rear passage  100   g  is tilted relative to the Y direction to the +Z side of the front passage  100   f . The plate member  408  is located in the front passage  100   f.    
     According to the third embodiment described above, when a part of the fluid flowing through the intake pipe IP in the Y direction (i.e., the forward direction) flows into the first passage  100 , the vortex is less likely to be generated as with the first embodiment and the second embodiment. 
     In the third embodiment, when the fluid flowing through the intake pipe IP in the −Y direction (i.e., a reverse direction of the forward direction) flows into the second passage  200  through the third opening  220 , the following advantages can be obtained. That is, when the fluid flows in the −Y direction through the intake pipe IP, the fluid flowing into the rear passage  100   g  through the second opening  120  is likely to generate a vortex VTa around the branching position BP due to a difference of slopes between the front passage  100   f  and the rear passage  100   g . The vortex VTa draws the fluid flowing from the third opening  220  to the flow rate detector  300  into the first passage  100   a  and restricts the fluid flowing through the rear passage  100   g  from the second opening  120  from flowing into the second passage  200 . Thus, the fluid is not restricted from flowing into the flowmeter  14  through the third opening  220 . 
     As described above, the flowmeter  14  does not restrict the fluid from flowing toward the flow rate detector  300  through the third opening  220  when the fluid flows backward in the intake pipe IP. Thus, the flowmeter  14  is effective when the flow rate detector  300  measures a flow rate of the fluid flowing in both forward and backward directions. 
     D. Other Embodiments 
     As shown in  FIG. 8 , a flowmeter  10   a  of a fourth embodiment differs from the flowmeter  10  of the first embodiment  10  in that the flowmeter  10   a  includes a plate member  402   a  in place of the plate member  402  and the plate member  404 . Other configurations are similar to those of the first embodiment. Each of the plate member  402  and the plate member  404  of the first embodiment has the −Y side end that is located at the −Y side end of the first passage  100 , but the present disclosure is not limited to this. As shown in  FIG. 8 , the −Y side end of the plate member  402   a  may be located between the −Y side end and +Y side end of the first passage  100 . The flowmeter  10   a  of the fourth embodiment can obtain the same advantages with those of the first embodiment. 
     As shown in  FIG. 9 , a flowmeter  10   b  of a fifth embodiment differs from the flowmeter  10  of the first embodiment shown in  FIG. 1  in that the flowmeter  10   b  includes a plate member  402   b  and a plate member  404   b  in place of the plate member  402  and the plate member  404 . Other configurations are similar to those of the flowmeter  10  of the first embodiment. As shown in  FIG. 9 , each of −Y side ends of the plate member  402   b  and the plate member  404   b  may be located on a −Y side of the −Y side end of the first passage  100 . That is, a part of each of the plate member  402   b  and the plate member  404   b  may be exposed to an outside of the first opening  110 . The flowmeter  10   b  of the fifth embodiment can obtain similar advantages as those of the first embodiment. 
     A flowmeter  10   c  of a sixth embodiment shown in  FIG. 10  differs from the flowmeter  10  of the first embodiment shown in  FIG. 2  in that the flowmeter  10   c  includes a plate member  402   c  and a plate member  404   c  in place of the plate member  402  and the plate member  404 . Other configurations are similar to those of the flowmeter  10  of the first embodiment. Each of the plate member  402  and the plate member  404  of the first embodiment has a length in the X direction that crosses the first passage  100  in the X direction, but the present disclosure is not limited to this. For example, as shown in  FIG. 10 , a length in the X direction of each of the plate member  402   c  and the plate member  404   c  may be shorter than a length of the first passage  100  in the X direction. The plate member  402   c  and the plate member  404   c  are fixed to an inner wall surface of the first passage  100  that is located on a +X side of the first passage  100 . The flowmeter  10   c  of the sixth embodiment can obtain similar advantages to those of the first embodiment. 
     As shown in  FIG. 11 , a flowmeter  10   d  of a seventh embodiment differs from the flowmeter  10  of the first embodiment shown in  FIG. 2  in that the flowmeter  10   d  includes a plate member  402   d  in place of the plate member  402  and the plate member  404 . Other configurations are similar to those of the flowmeter  10  of the first embodiment. The plate member  402   d  has a lattice shape that divides the first passage  100 . The flowmeter  10   d  of the seventh embodiment can obtain similar advantages to those of the first embodiment. 
     As shown in  FIGS. 12 and 13 , a flowmeter  10   e  of an eighth embodiment differs from the flowmeter  10  of the first embodiment shown in  FIGS. 1 and 2  in that the flowmeter  10   e  includes a member ST. Other configurations are similar to those of the flowmeter  10  of the first embodiment. The flowmeter  10   e  includes the member ST on a −Z side of the first passage  100 . An appearance of the member ST has a quadrangular prism shape. Because of the member ST, the flowmeter  10   e  can reduce a difference between an amount of the fluid reflected at a portion of the flowmeter  10   e  on a +Z side of the first opening  110  and changing its direction and an amount of the fluid reflected at a portion of the flowmeter  10   e  on a −Z side of the first opening  110  compared to the flowmeter  10  of the first embodiment. As a result, a difference between a velocity of the flow UF and a velocity of the flow DF can be decreased and a variation of the flow rate of the fluid flowing into the first passage  100  is restricted from generating at the edge of the first opening  110 . As a result, the vortex VT is further restricted from generating in the first passage  100 . A shape of the member ST is not limited to a shape in  FIG. 12  while the member ST extends from the first opening  110  in the −Z direction. 
     As shown in  FIG. 14 , a flowmeter  12   a  of a ninth embodiment differs from the flowmeter  12  of the second embodiment shown in  FIG. 5  in that the flowmeter  12   a  includes a protrusion  504 . Other configurations are similar to those of the second embodiment. The flowmeter  12   a  includes the protrusion  504  protruding from a portion of the edge of the first opening  110  located on the −Z side of the edge in addition to the protrusion  502  protruding from a portion of the edge of the first opening  110  located on the +Z side of the edge. A length of the protrusion  504  in the Y direction is the same as a length of the protrusion  502  in the Y direction. The flowmeter  12   a  can also reduce a difference between a velocity of the flow UF and a velocity of the flow DF as with the flowmeter  12  of the second embodiment. Thus, the fluid is restricted from biasedly flowing into the first passage  100  around the edge of the first opening  110 . Therefore, the vortex VT is less likely to be generated in the first passage  100  and a deterioration of the flow rate detector  300 , which is caused by the fluid restricted from flowing into the second passage  200 , can be restricted. 
     As shown in  FIG. 15 , a flowmeter  12   b  of a tenth embodiment differs from the flowmeter  12  of the second embodiment shown in  FIG. 5  in that the flowmeter  12   b  includes a protrusion  506 . Other configurations are similar to those of the flowmeter  12  of the second embodiment. The flowmeter  12   a  includes the protrusion  506  protruding from a portion of an edge of the second opening  120  on a +Z side of the edge in addition to the protrusion  502  protruding from the portion of the edge of the first opening  110  on the +Z side of the edge. When the fluid flows backward through the intake pipe IP in the −Y direction and a part of the fluid flows into the first passage  100  through the second opening  120 , the flowmeter  12   b  can restrict the fluid from biasedly flowing into the first passage  100  around the edge of the second opening  120   
     As shown in  FIG. 16 , a flowmeter  12   c  of an eleventh embodiment differs from the flowmeter  12  of the second embodiment in  FIG. 6  in that the flowmeter  12   c  includes a protrusion  502   c  that has a different shape from the protrusion  502  in place of the protrusion  502 . Other configurations are similar to those of the flowmeter  12  of the second embodiment. The protrusion  502   c  has a curved shape viewed from a −Z side of the protrusion  502   c . The flowmeter  12   c  of the eleventh embodiment has similar advantages to those of the second embodiment. 
     As shown in  FIG. 17 , a flowmeter  12   d  of a twelfth embodiment differs from the flowmeter  12  of the second embodiment shown in  FIG. 6  in that the flowmeter  12   d  includes a protrusion  502   d  that has a different shape from the protrusion  502  in place of the protrusion  502 . Other configurations are similar to those of the flowmeter  12  of the second embodiment. The protrusion  502   d  has a trapezoidal shape viewed from a −Z side of the protrusion  502   d . The flowmeter  12   d  of the twelfth embodiment has similar advantages to those of the second embodiment. 
     As shown in  FIG. 18 , a flowmeter  12   e  of a thirteenth embodiment differs from the flowmeter  12  of the second embodiment shown in  FIG. 6  in that the flowmeter  12   e  includes a protrusion  502   e  in place of the protrusion  502 . Other configurations are similar to those of the flowmeter  12  of the second embodiment. The protrusion  502   e  has a tubular shape that defines a through hole passing through the protrusion  502   e  in the Y direction. The protrusion  502   e  may be formed by extending the first passage  100  in the −Y direction. The flowmeter  12   e  of the thirteenth embodiment has similar advantages to those of the second embodiment. 
     As shown in  FIG. 19 , a flowmeter  12   f  of a fourteenth embodiment differs from the flowmeter  12  of the second embodiment in that the flowmeter  12   f  includes the plate member  410  and defines a fourth opening  115 . The plate member  410  has a +Y side end located within the area R. The plate member  410  has a −Y side end located at the −Y side end of the first passage  100 . The fourth opening  115  is defined between the first opening  110  and the opening CS at the branching position of the second passage  200 . The fourth opening opens in the +X direction. The fourth opening  115  is an opening through which dusts and water accumulated in the first passage  100  flows out. The flowmeter  12   f  of the fourteenth embodiment has similar advantages to those of the first embodiment. 
     The present disclosure should not be limited to the embodiments and modifications described above, and various other embodiments may be implemented without departing from the scope of the present disclosure. For example, the technical features in the embodiments can be replaced or combined as appropriate. Also, if the technical features are not described as essential in the present specification, they can be deleted as appropriate.