JP4750895B1 - Powder flow measuring device - Google Patents

Abstract

Provided is a powder flow rate measuring apparatus capable of performing measurement with higher accuracy than ever before.
A powder flow rate measuring apparatus 1 according to the present invention includes a cylindrical tube 10 made of an insulating material as a flow path of powder to be measured, and a substantially cylindrical tube disposed so as to cover the outer periphery of the cylindrical tube 10 The casing 20 is fixed to the inner surface of the casing 20 with the fixing member 30 interposed therebetween, and a predetermined gap is provided between the outer surface of the cylindrical tube 10 and a predetermined gap between the inner surface of the casing 20. A pair of counter electrodes 40a, 40b arranged with a gap.
[Selection] Figure 1

Description

  The present invention relates to an apparatus for measuring the flow rate of a powder flowing in a tube together with a gas, and more particularly to a capacitance type powder flow rate measuring apparatus that measures the flow rate of a powder by changing the capacitance.

  Conventionally, as a device for measuring the flow rate of powder conveyed by a gas such as air, a capacitance type that measures the flow rate of powder by measuring the capacitance value that changes according to the flow rate of powder. Powder flow rate measuring devices are widely used. This capacitance-type powder flow rate measuring device includes a pair of counter electrodes to which an AC voltage is applied, and changes in the capacitance between the counter electrodes, which change according to the amount of powder, Output as a change.

  As such a capacitance-type powder flow rate measuring device, for example, a device in which a pair of rectangular electrodes are arranged along the tube axis direction on the outer peripheral surface of a transfer tube for transferring powder (for example, see Patent Document 1). ) Has been proposed. However, the powder flow rate measuring apparatus provided with such a counter electrode has a problem that the measurement sensitivity in the cross-sectional direction of the tube becomes non-uniform. That is, there is a problem that the measurement accuracy is low because the measured value varies depending on which position in the cross section in the transport pipe the powder passes.

  In order to solve such a problem, a powder flow rate measuring apparatus (see, for example, Patent Document 2) in which a pair of strip-like electrodes are spirally wound around the outer periphery of a transport pipe has been proposed. By forming the pair of counter electrodes in the form of two spirals, the direction of the electric lines of force generated between the counter electrodes can be changed in the tube axis direction. It becomes possible to reduce the non-uniformity of the measurement sensitivity (in the position).

Japanese Patent Laid-Open No. 60-14153 JP 2006-329874 A

  However, although the powder flow rate measuring device described in Patent Document 2 can reduce the measurement sensitivity non-uniformity in the cross-sectional direction of the tube to some extent, the measurement accuracy required in recent years (for example, ± 1 to ± 1). 5%) is difficult to satisfy. In particular, when the powder is transported with a high-pressure gas, the passage position of the powder fluctuates drastically, so that it is very difficult to perform high-precision measurement.

  In view of such circumstances, the present invention intends to provide a powder flow rate measuring apparatus capable of performing measurement with higher accuracy than ever before.

(1) The present invention provides a cylindrical tube made of an insulating material as a flow path of the powder to be measured, a substantially cylindrical casing disposed so as to cover the outer periphery of the cylindrical tube, and a fixing member. A pair of counter electrodes that are fixed to the inner side surface of the casing with a predetermined gap provided between the cylindrical tube and the outer peripheral surface of the cylindrical tube, and provided with a predetermined gap between the inner side surface of the casing; The distance between the inner surface of the casing and the outer surface of the pair of counter electrodes is set to be equal to or greater than the distance between the outer peripheral surface of the cylindrical tube and the inner surfaces of the pair of counter electrodes. This is a powder flow rate measuring device.

  (2) The present invention is also characterized in that the pair of counter electrodes has a spiral shape that goes around the outside of the cylindrical tube, and is arranged symmetrically with respect to the axis of the cylindrical tube. It is a powder flow rate measuring apparatus as described in (1).

  (3) The present invention is also characterized in that the pair of counter electrodes have a width in a cross section perpendicular to the axis of the cylindrical tube set in a range of 50 to 80 degrees in a circumferential direction of the cylindrical tube. The powder flow rate measuring device according to (2) above.

  (4) In the powder flow rate measuring device according to (2) or (3), the pair of counter electrodes may have a spiral shape with a spiral angle of 20 to 40 degrees. is there.

  (5) The present invention is also characterized in that the pair of counter electrodes have a spiral shape that circulates in a range of 160 to 200 degrees in the circumferential direction of the cylindrical tube. The powder flow rate measuring device according to any one of the above.

  (6) In the present invention, the distance between the outer peripheral surface of the cylindrical tube and the inner surfaces of the pair of counter electrodes is set to a distance of 0.5 to 6% of the outer diameter of the cylindrical tube. The powder flow rate measuring device according to any one of the above (1) to (5).

( 7 ) Further, in the present invention, the casing has a halved structure including a first member and a second member divided in a radial direction, and one of the pair of counter electrodes is fixed to the first member, The powder flow rate measuring device according to any one of (1) to ( 6 ), wherein the other is fixed to the second member.

(8) The present invention also provides the casing is composed of a conductive material, wherein the fixing member, characterized in that it is constituted of an insulating material, according to any one of the above (1) through (7) This is a powder flow rate measuring device.

( 9 ) The powder flow rate according to any one of (1) to ( 8 ), wherein the pair of counter electrodes is formed by bending a parallelogram plate. It is a measuring device.

  According to the powder flow rate measuring apparatus according to the present invention, it is possible to achieve an excellent effect that it is possible to perform measurement with higher accuracy than before.

(A) It is sectional drawing at the time of seeing the powder flow rate measuring apparatus which concerns on embodiment of this invention from one direction. (B) It is sectional drawing at the time of seeing the powder flow rate measuring apparatus from the direction orthogonal to Fig.1 (a). (A) It is the sectional view on the AA line of FIG.1 (b). (B) It is the BB sectional drawing of FIG.1 (b). It is the schematic which showed the circuit structure of the powder flow rate measuring apparatus. (A) It is the figure which showed the 2nd member and counter electrode of the casing. (B) It is CC sectional view taken on the line of Fig.4 (a). It is the figure which showed the attachment method of the casing and counter electrode to a cylindrical tube. It is the figure which showed the formation method of a counter electrode.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

  Fig.1 (a) is sectional drawing at the time of seeing the powder flow rate measuring apparatus 1 which concerns on this embodiment from one direction, The figure (b) is powder from the direction orthogonal to the figure (a). It is sectional drawing at the time of seeing the flow measuring device 1. FIG. 2A is a cross-sectional view taken along the line AA in FIG. 1B, and FIG. 2B is a cross-sectional view taken along the line BB in FIG. 1B.

  As shown in these drawings, the powder flow rate measuring device 1 includes a cylindrical tube 10 serving as a powder flow path, a casing 20 disposed so as to cover the outer periphery of the cylindrical tube 10, and an inner surface of the casing 20. It is an electrostatic capacitance type measuring device comprised of a plurality of fixing members 30 fixed to a pair and a pair of counter electrodes 40a, 40b fixed to the casing 20 via the fixing members 30. 1A and 1B are views showing the casing 20 in cross section.

  The cylindrical tube 10 is a tube through which powder flows by gas conveyance (which may be high-pressure gas), and constitutes a part of the powder conveyance tube whose flow rate is measured by the powder flow rate measuring device 1. Is. The cylindrical tube 10 is made of an insulating material having a low relative dielectric constant such as resin, ceramics, or quartz glass so as not to affect the capacitance between the counter electrodes 40a and 40b. The cylindrical tube 10 may be one in which a part of a powder conveyance pipe made of an insulating material is used as it is, or a dedicated pipe added through a flange joint or the like in the middle of the powder conveyance pipe. It may be.

  The casing 20 is a hollow cylindrical member that covers the outer periphery of the cylindrical tube 10 in a state where the counter electrodes 40a and 40b are accommodated therein. Insertion holes 22 are provided at both ends of the casing 20, and the cylindrical tube 10 is inserted into the insertion holes 22, whereby the casing 20 and the counter electrodes 40 a and 40 b are fixed to the cylindrical tube 10. . In the present embodiment, the casing 20 is made of a conductive material (for example, a metal such as aluminum), so that the casing 20 functions as an electromagnetic shield.

  In the present embodiment, the casing 20 is configured in a cylindrical shape, but may be configured in other shapes such as a polygonal shape and a capsule shape. Moreover, you may make it provide an opening, a window, etc. in each part of the casing 20 as needed.

  In the present embodiment, the casing 20 has a halved structure including the first member 20a and the second member 20b so that the casing 20 can be easily detached from the cylindrical tube 10 together with the counter electrodes 40a and 40b. The first member 20a and the second member 20b are respectively formed with projecting portions 24a and 24b projecting in the radial direction on the mating surfaces, and the first member 20a and the second member 20b are formed on the projecting portions 24a and 24b, respectively. A plurality of bolt holes 26b through which bolts 50 for connecting the two are inserted are respectively formed.

  The fixing member 30 is a member for fixing the counter electrodes 40 a and 40 b with a predetermined gap between them and the inner surface of the casing 20. In the present embodiment, the counter electrode 40a is fixed to the first member 20a of the casing 20 via the five block-shaped fixing members 30, and similarly, the counter electrode 40b is fixed to the casing via the five block-shaped fixing members 30. 20 is fixed to the second member 20b. The fixing member 30 has a base end fixed to the inner surface of the casing 20 by a known method such as a screw, an engagement pin, or an adhesive. Then, the counter electrodes 40 a and 40 b are fixed to the distal end portion of the fixing member 30 by a known method such as a screw, an engagement pin, or an adhesive.

  In this embodiment, since the casing 20 is made of a conductive material, the fixing member 30 is made of an insulating material (for example, Teflon (registered trademark) resin or silicon resin). That is, the fixing member 30 of the present embodiment is configured to block conduction between the counter electrodes 40 a and 40 b and the casing 20. Further, in the present embodiment, the fixing member 30 is made of a material having a low thermal expansion coefficient, and the counter electrodes 40a and 40b and the cylindrical tube 10 are formed even when the gas and powder flowing inside the cylindrical tube 10 are at a high temperature. In addition, the positional relationship with the casing 20 is not significantly changed. The shape of the fixing member 30 may be other shapes as long as the counter electrode 40a can be fixed. Needless to say, the number of the fixing members 30 can be increased or decreased as necessary.

  The pair of counter electrodes 40 a and 40 b are strip-shaped electrodes that spiral around the outer periphery of the cylindrical tube 10 within a range of 180 degrees, and provide a predetermined gap between the inner surface and the outer peripheral surface of the cylindrical tube 10. Are arranged. The counter electrodes 40 a and 40 b are configured in the same shape as each other, and are arranged so as to be axially symmetric with respect to the axis O of the cylindrical tube 10. Furthermore, both end faces 40a1 and 40a2 of the counter electrode 40a and both end faces 40b1 and 40b2 of the counter electrode 40b are formed to be parallel to a cross section perpendicular to the axis O, and the end face 40a1 of the counter electrode 40a and the counter electrode 40b are formed. The position of the end face 40b1 in the direction of the axis O and the position of the end face 40a2 of the counter electrode 40a and the position of the end face 40b2 of the counter electrode 40b in the direction of the axis O are substantially the same. The material constituting the counter electrodes 40a and 40b may be any conductive material that functions as an electrode, and for example, metals such as copper, aluminum, and iron can be employed.

  In the present embodiment, by providing a gap, that is, an air layer, between the cylindrical tube 10 and the counter electrodes 40a and 40b, the electric lines of force between the counter electrodes 40a and 40b are disturbed by the material constituting the cylindrical tube 10 ( The measurement accuracy is improved by reducing the uniformity of electric field lines).

  Specifically, the resin, ceramics, and the like constituting the cylindrical tube 10 are dielectrics having a relative dielectric constant of about 3 to 10, and are far more than air having a relative dielectric constant (1.000586) substantially equal to that of vacuum. It has a large dielectric property. For this reason, when the counter electrodes 40a and 40b and the cylindrical tube 10 are brought into contact with or close to each other, the influence of the dielectric property of the cylindrical tube 10 is increased, and the lines of electric force between the counter electrodes 40a and 40b are unevenly disturbed. turn into. Such disturbance of the lines of electric force directly causes nonuniformity of the measurement sensitivity in the cross-sectional direction of the cylindrical tube 10, and therefore, in order to improve the uniformity of the measurement sensitivity, a uniform electric power with no disturbance as much as possible is possible. It is necessary to generate a field line.

  Therefore, in the present embodiment, a predetermined gap is provided between the cylindrical tube 10 and the counter electrodes 40a and 40b to generate an air layer having a relative dielectric constant substantially equal to that of a vacuum, whereby the dielectric of the cylindrical tube 10 is generated. The uniformity of the electric lines of force between the counter electrodes 40a and 40b is increased by reducing the influence of the property, and the uniformity of measurement sensitivity is improved.

  Furthermore, in the present embodiment, the counter electrodes 40a and 40b are configured to have the same size and shape, and are arranged so as to be axially symmetric with respect to the axis O of the cylindrical tube 10, whereby FIG. And as shown in (b), the opposing electrodes 40a, 40b are opposed to each other with the same width in each cross section of the cylindrical tube 10, and are symmetrically opposed about the axis O. By doing in this way, as shown by line E in the same figure (a) and (b), the line of a straight line of electric force substantially parallel between counter electrodes 40a and 40b is made into a section (axis O of cylindrical tube 10). For each of the cross sections perpendicular to each other), the uniformity of the lines of electric force between the counter electrodes 40a, 40b can be increased, and the uniformity of the measurement sensitivity can be further improved.

  Since the counter electrodes 40a and 40b are formed in a spiral shape, the direction of the substantially parallel linear electric lines of force gradually changes along the direction of the axis O of the cylindrical tube 10. . In this embodiment, the rate of change in the direction of the electric lines of force can be set by setting the spiral angle of the counter electrodes 40a, 40b, that is, the tilt angle with respect to the axis O (helical axis) of the cylindrical tube 10 to be relatively smaller than that of the related art. I try to reduce it. By doing in this way, the uniformity of the line of electric force between counter electrode 40a, 40b can be improved more.

  Further, by setting the spiral angle of the counter electrodes 40a and 40b to be relatively small, the distance G in the direction of the axis O when the counter electrodes 40a and 40b are arranged symmetrically with respect to the axis O of the cylindrical tube 10 ( It becomes possible to enlarge (refer FIG.1 (b)). Thereby, since the density of the electric lines of force produced in directions other than the cross-sectional direction of the cylindrical tube 10 can be reduced, the uniformity of the electric lines of force between the counter electrodes 40a and 40b can be further increased. The distance G is preferably 1.5 times or more the width X of the cylindrical tube 10 in the direction of the axis O of the counter electrode 40a, 40b.

  The casing 20 is provided with connectors 60a and 60b, and the counter electrodes 40a and 40b are electrically connected to external devices via the connectors 60a and 60b. Specifically, the first member 20a of the casing 20 is provided with a connector 60a that conducts with the counter electrode 40a, and the second member 20b is provided with a connector 60b that conducts with the counter electrode 40b. As these connectors 60a and 60b, known connectors having excellent insulation characteristics and high-frequency characteristics such as BNC connectors, M connectors, and N connectors can be used.

  FIG. 3 is a schematic diagram showing a circuit configuration of the powder flow rate measuring apparatus 1. As shown in the figure, the counter electrode 40b is connected to an AC power source 70 that applies an AC voltage to the counter electrodes 40a and 40b, and the counter electrode 40b includes a detection circuit 80 that detects a change in capacitance, and a detection circuit. It is connected to an output circuit 90 that amplifies the signal of the circuit 80 and outputs it to an external arithmetic processing unit (not shown). The casing 20 is grounded in order to function as an electromagnetic shield. Needless to say, either of the counter electrodes 40 a and 40 b may be connected to the AC power source 70.

  When an AC voltage is applied to the counter electrodes 40a and 40b by the AC power source 70, the capacitance between the counter electrodes 40a and 40b changes according to the flow rate of the powder flowing in the cylindrical tube 10. The detection circuit 80 detects this change in capacitance as a change in current value, and the output circuit 90 amplifies the signal from the detection circuit and outputs it to an external arithmetic processing unit. An arithmetic processing unit such as a computer calculates a flow rate of powder per unit time by performing predetermined arithmetic processing on the signal from the output circuit 90.

  When measuring the flow rate of the powder, measure the reference capacitance in the state of flowing only the gas in advance, and adjust the pressure, temperature, humidity, etc. of the gas as the parameters for correcting the measurement results. Sometimes measured. In the powder flow rate measuring apparatus 1 of the present embodiment, the measurement sensitivity is greatly improved as compared with the conventional measuring apparatus, and therefore, accompanying the pressure change of the gas in the cylindrical tube 10 (change in the density of gas molecules). It is possible to detect a change in capacitance. That is, according to the powder flow rate measuring apparatus 1 of the present embodiment, not only the powder flow rate but also the gas pressure in the cylindrical tube 10 can be measured.

  Next, details of the dimensional shape and arrangement of the counter electrodes 40a and 40b will be described.

  FIG. 4A is a view showing the second member 20b and the counter electrode 40b of the casing 20, and FIG. 4B is a cross-sectional view taken along the line CC of FIG. The first member 20a and the second member of the casing 20 have the same shape, and the counter electrode 40a fixed to the first member 20a and the counter electrode 40b fixed to the second member 20b are also the same member. Here, description will be made based on a diagram showing the counter electrode 40b fixed to the second member 20b.

  The inventor of the present invention has conducted various experiments on the dimensional shape and arrangement of the counter electrodes 40a and 40b, and has found the optimum dimensional shape and arrangement for performing highly accurate measurement. First, the width of the counter electrode 40a, 40b in the circumferential direction of the cylindrical tube 10 is represented by an angle θ about the axis O of the cylindrical tube 10 as shown in FIG. It is preferably in the range of ˜80 degrees, more preferably in the range of θ to 55 to 75 degrees, and most preferably in the range of 60 to 70 degrees. By setting the circumferential width of the cylindrical tube 10 of the counter electrodes 40a and 40b in this way, parallel and uniform linear electric lines of force between the counter electrodes 40a and 40b are made to the dielectric of the cylindrical tube 10. It is possible to generate as wide a range as possible without being affected.

  Next, the spiral angle α of the counter electrodes 40a and 40b (see FIG. 5A) is preferably within a range of 20 to 40 degrees, more preferably within a range of 25 to 35 degrees, Most preferably within the range of 33 degrees. By setting the spiral angle α in this way, the rate of change in the direction of the axis O in the direction of the electric force lines can be reduced, and the uniformity of the electric force lines between the counter electrodes 40a and 40b can be further increased. Even when the circumferential width of the cylindrical tube 10 of the counter electrodes 40a and 40b is set as described above, the gap G in the direction of the axis O of the counter electrodes 40a and 40b (see FIG. 1B). ) Can be increased as long as it is not redundant.

  Next, the distance a (see FIG. 4B) between the inner surface of the counter electrodes 40a and 40b and the outer peripheral surface of the cylindrical tube 10 is in the range of 0.5 to 6% of the outer diameter D of the cylindrical tube 10. The distance is preferably within the range of 1 to 5% of the outer diameter D, and more preferably within the range of 2 to 4% of the outer diameter D. By setting the distance a of the gap in this way, it is possible to eliminate the influence of the dielectric of the cylindrical tube 10 and to generate a uniform line of electric force between the counter electrodes 40a and 40b.

  When importance is attached to the ease of manufacture of the powder flow rate measuring apparatus 1, for example, the clearance distance a is set to 1 to 1 with respect to the cylindrical tube 10 having a general size (the outer diameter D is about 10 to 300 mm). You may make it set the distance a of a clearance to the distance which can be manufactured easily so that it may set to about 8 mm.

  Next, the distance b (see FIG. 4B) between the outer surfaces of the counter electrodes 40a and 40b and the inner surface of the casing 20 is not particularly limited, but the influence of the casing 20 is excluded. In order to generate uniform lines of electric force, it is preferable that the distance is some distance, and it is preferable that the distance is at least the distance a.

  Moreover, it is preferable that the rotation angle β (see FIG. 4B) of the counter electrodes 40a and 40b around the cylindrical tube 10 is an angle of about 180 degrees. More specifically, the lap angle β is preferably in the range of 160 to 200 degrees, more preferably in the range of 170 to 190 degrees, and most preferably 180 degrees. Considering the change in the direction of the electric force lines in the direction of the axis O, the electric force lines can be generated evenly at each position on the cross section in the cylindrical tube 10 by setting the rotation angle β = 180 degrees. Therefore, in this embodiment, β = 180 degrees.

  In a conventional powder flow measuring device including a spiral counter electrode, it is common sense to set the turn angle β to 360 degrees or more, and it is impossible to obtain sufficient measurement accuracy unless it is set to 360 degrees or more. It was. On the other hand, according to the configuration of the present embodiment, it is possible to perform measurement with higher accuracy than before even when the circulatory angle β is set to an angle of about 180 degrees. Therefore, in the powder flow rate measuring apparatus 1 of the present embodiment, the length in the direction of the axis O can be made more compact than before. Moreover, it becomes possible to make the casing 20 into a half structure by setting the turning angle β in this way.

  In the present embodiment, as shown in FIG. 4B, the rotation angle β is set between the width direction center 40b1a of one end face 40b1 of the counter electrode 40b and the width direction center 40b2a of the other end face 40b2. It is set and β = 180 degrees (the same applies to the counter electrode 40a). In order to improve the measurement accuracy, it is preferable to set the rotation angle β as accurately as possible in each of the counter electrodes 40a and 40b. As shown in FIG. 5B, the one end face 40b1 of the counter electrode 40b is formed. It is preferable that the center 40b1a in the width direction and the center 40b2a in the width direction of the other end face 40b2 are aligned with the axis O in a substantially straight line.

  Specifically, the error range of the position of the width direction center 40b2a of the other end face 40b2 with respect to the position of the width direction center 40b1a of the one end face 40b1 of the counter electrode 40b is preferably within a range of −5 to +5 degrees. , More preferably within a range of −3 to +3 degrees, and most preferably within a range of −1 to +1 degrees. The same applies to the counter electrode 40a.

  FIG. 5 is a view showing a method of attaching the casing 20 and the counter electrodes 40a and 40b to the cylindrical tube 10. As shown in FIG. As shown in the figure, in the present embodiment, the first member 20a and the second member 20b are sandwiched from both sides of the cylindrical tube 10, and the bolt 50 and the nut 52 are fastened, so that the casing 20 and The counter electrodes 40 a and 40 b can be attached to the cylindrical tube 10. Further, by removing the bolt 50 and the nut 52 and dividing the casing 20 into the first member 20a and the second member 20b, the casing 20 and the counter electrodes 40a and 40b can be easily detached from the cylindrical tube 10. That is, the powder flow rate measuring apparatus 1 of the present embodiment has greatly improved maintainability compared to the conventional one.

  For example, when the cylindrical tube 10 made of resin is worn by contact with powder, the casing 20 can be divided and removed immediately, so that the cylindrical tube 10 can be easily and quickly replaced. When the powder conveyance tube is made of a material having a low relative dielectric constant from the beginning, the powder flow rate measuring device 1 can be directly attached to the conveyance tube for measurement without cutting the conveyance tube. it can.

  FIG. 6 is a diagram showing a method of forming the counter electrodes 40a and 40b. In the present embodiment, as shown in the figure, the counter electrodes 40a and 40b are formed by bending a parallelogram-shaped plate 41 having an inclination angle α. Here, the width W of the plate 41 corresponds to the circumferential width of the cylindrical tube 10 of the counter electrodes 40a, 40b, and is W = π (D + 2a) (θ / 360). H corresponds to the length of the counter electrode 40a, 40b in the direction of the axis O of the cylindrical tube 10, and H = L / tan α. Here, L = π (D + 2a) (β / 360).

  The width direction centers 41a1 and 41b1 of both end surfaces 41a and 41b of the plate 41 are the width direction centers 40a1 and 40a2a of both end surfaces 40a1 and 40a2 of the counter electrode 40a and the width direction centers 40b1a of both end surfaces 40b1 and 40b2 of the counter electrode 40b. 40b2a, respectively. Accordingly, the plate 41 is bent so that the space between the centers 41a1 and 41b1 in the width direction has a turning angle β.

  The electrostatic capacitance between the counter electrodes 40a and 40b is a value proportional to the area S = W · H of the counter electrodes 40a and 40b. Therefore, by adjusting the values of the parameters a, θ, α, and β as appropriate based on the outer diameter D of the cylindrical tube 10 to set the area S of the counter electrodes 40a and 40b, the distance between the counter electrodes 40a and 40b is set. The capacitance can be set to an optimum value according to the measurement conditions.

  The counter electrodes 40a and 40b may be formed by a method other than the above, for example, may be formed by casting or forging, or a cylindrical material is cut into a spiral shape. It may be formed by doing. Further, the thicknesses of the counter electrodes 40a and 40b are not particularly limited, but it is preferable to have a thickness of several mm for the cylindrical tube 10 having a general size.

  As described above, the powder flow rate measuring device 1 according to the present embodiment is disposed so as to cover the outer periphery of the cylindrical tube 10 made of an insulating material as the flow path of the powder to be measured. The cylindrical casing 20 is fixed to the inner surface of the casing 20 with the fixing member 30 interposed therebetween, and a predetermined gap is provided between the outer surface of the cylindrical tube 10 and the inner surface of the casing 20. And a pair of counter electrodes 40a and 40b disposed with a predetermined gap.

  By adopting such a configuration, it becomes possible to eliminate the influence of the dielectric property of the cylindrical tube 10 and generate uniform lines of electric force, and the flow rate of the powder flowing in the cylindrical tube 10 can be increased with higher accuracy than before. Can be done. In addition, according to the experimental results of the inventors of the present invention, the variation in measurement sensitivity in the cross-sectional direction of the cylindrical tube 10 (at a position on the cross-section of the tube) can be made within 5%, which is far more than conventional. Highly accurate measurement can be performed. Further, not only the flow rate of the powder but also the pressure of the gas in the cylindrical tube 10 can be measured.

  In addition, in this embodiment, although the example at the time of making the casing 20 into a half structure was shown, this invention is not limited to this, The casing 20 may be comprised integrally. .

  The pair of counter electrodes 40 a and 40 b has a spiral shape that goes around the outside of the cylindrical tube 10, and is arranged symmetrically with respect to the axis O of the cylindrical tube 10. By doing in this way, it becomes possible to improve the uniformity of the measurement sensitivity in the cross-sectional direction of the cylindrical tube 10, and the measurement accuracy can be further improved.

  The pair of counter electrodes 40 a and 40 b has a width in a cross section perpendicular to the axis O of the cylindrical tube 10 in a range of 50 to 80 degrees in the circumferential direction of the cylindrical tube 10. By doing in this way, it becomes possible to generate a more uniform straight line of electric force while eliminating the influence of the dielectric property of the cylindrical tube 10, and the measurement accuracy can be further improved.

  The pair of counter electrodes 40a and 40b has a spiral shape with a spiral angle α of 20 to 40 degrees. By doing in this way, it becomes possible to further improve the uniformity of the lines of electric force, and to further improve the measurement accuracy.

  The pair of counter electrodes 40 a and 40 b have a spiral shape that circulates in the range of 160 to 200 degrees in the circumferential direction of the cylindrical tube 10. By doing in this way, the axial direction dimension of an apparatus can be made compact, improving a measurement precision. In addition, since the casing 20 has a half structure, and the casing 20 and the counter electrodes 40a and 40b can be divided in the radial direction of the cylindrical tube 10, it is very easy to attach and remove the apparatus. Maintenance such as replacement can be facilitated.

  The distance a between the outer peripheral surface of the cylindrical tube 10 and the inner surfaces of the pair of counter electrodes 40 a and 40 b is set to a distance of 0.5 to 6% of the outer diameter D of the cylindrical tube 10. By doing in this way, reduction of the influence of the dielectric of the cylindrical tube 10 and improvement of measurement sensitivity can be balanced at a high level.

  The distance b between the inner surface of the casing 20 and the outer surfaces of the pair of counter electrodes 40a, 40b is equal to or greater than the distance a between the outer peripheral surface of the cylindrical tube 10 and the inner surfaces of the pair of counter electrodes 40a, 40b. Is set to By doing in this way, the influence of the casing 20 can be eliminated and the measurement accuracy can be further improved.

  The casing 20 has a halved structure including a first member 20a and a second member 20b that are divided in the radial direction. One of the pair of counter electrodes 40a and 40b is fixed to the first member 20a, and the other is It is fixed to the second member 20b. By doing in this way, attachment and removal with respect to the cylindrical pipe | tube 10 of the casing 20 and the counter electrodes 40a and 40b can be made very easy, and maintenance property can be improved.

  The casing 20 is made of a conductive material, and the fixing member 30 is made of an insulating material. By doing in this way, it becomes possible to make the casing 20 function as an electromagnetic shield, the influence of disturbance can be excluded, and measurement accuracy can be further improved.

  In the present embodiment, an example in which the block-shaped fixing member 30 is used has been described. However, the present invention is not limited to this, and for example, a layer of an insulating material as the fixing member 30 on the inner surface of the casing 20. The counter electrodes 40a and 40b may be attached to the inner surface of the layer of insulating material. Further, the counter electrodes 40 a and 40 b may be formed on, for example, a film substrate, and the film substrate may be attached to the inner surface of the casing 20 to function as the fixing member 30.

  The pair of counter electrodes 40a and 40b is formed by bending a parallelogram-shaped plate 41. By doing in this way, it becomes possible to form counter electrode 40a, 40b with high precision at low cost, and counter electrode 40a, 40b can be made to oppose correctly, and a measurement precision can further be improved.

  Although the embodiment of the present invention has been described above, the powder flow rate measuring apparatus of the present invention is not limited to the above-described embodiment, and various modifications are made within the scope not departing from the gist of the present invention. Of course you get.

  The powder flow rate measuring device of the present invention can be used in the field of conveying various powders by gas.

DESCRIPTION OF SYMBOLS 1 Powder flow rate measuring apparatus 10 Cylindrical tube 20 Casing 20a 1st member 20b 2nd member 30 Fixed member 40a, 40b Counter electrode 41 Parallelogram-shaped board a The distance of the clearance gap between the outer peripheral surface of a cylindrical tube, and the inner surface of a counter electrode b Distance between the inner surface of the casing and the outer surface of the counter electrode O The axial center of the cylindrical tube α The spiral angle of the counter electrode β The circular angle of the counter electrode θ The angle representing the circumferential width of the cylindrical tube of the counter electrode

Claims (9)

A cylindrical tube made of an insulating material as a flow path of the powder to be measured;
A substantially cylindrical casing arranged to cover the outer periphery of the cylindrical tube;
It is fixed to the inner surface of the casing with a fixing member in between, and is provided with a predetermined gap between the outer peripheral surface of the cylindrical tube and a predetermined gap with the inner surface of the casing. A pair of counter electrodes ,
The distance between the inner surface of the casing and the outer surface of the pair of counter electrodes is set to be equal to or greater than the distance between the outer peripheral surface of the cylindrical tube and the inner surfaces of the pair of counter electrodes. To
Powder flow measuring device. The pair of counter electrodes has a spiral shape that goes around the outside of the cylindrical tube, and is arranged symmetrically with respect to the axis of the cylindrical tube.
The powder flow rate measuring apparatus according to claim 1. The pair of counter electrodes have a width in a cross section perpendicular to the axis of the cylindrical tube set in a range of 50 to 80 degrees in a circumferential direction of the cylindrical tube,
The powder flow rate measuring apparatus according to claim 2. The pair of counter electrodes have a spiral shape with a spiral angle of 20 to 40 degrees,
The powder flow rate measuring apparatus according to claim 2 or 3. The pair of counter electrodes have a spiral shape that circulates in a range of 160 to 200 degrees in a circumferential direction of the cylindrical tube,
The powder flow rate measuring apparatus according to any one of claims 2 to 4. The distance between the outer peripheral surface of the cylindrical tube and the inner surface of the pair of counter electrodes is set to a distance of 0.5 to 6% of the outer diameter of the cylindrical tube,
The powder flow rate measuring apparatus according to any one of claims 1 to 5. The casing is a half structure composed of a first member and a second member divided in a radial direction,
One of the pair of counter electrodes is fixed to the first member, and the other is fixed to the second member.
The powder flow rate measuring apparatus according to any one of claims 1 to 6 . The casing is made of a conductive material;
The fixing member is made of an insulating material,
The powder flow rate measuring apparatus according to any one of claims 1 to 7 . The pair of counter electrodes are configured by bending a parallelogram plate,
The powder flow rate measuring apparatus according to any one of claims 1 to 8 .

Images