JP2006284300A - Vibration type measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove a measuring error caused by thermal expansion of a sensor tube. <P>SOLUTION: When a tensile load or a compressive load in the axial direction is applied to the sensor tube 14 by the difference between each thermal expansion coefficient of the sensor tube 14 and a storing case 12, a holding member 32 is slid in the extending direction (X-direction) of the sensor tube 14 in a through hole 22c of an inflow side case 22 and operated so that the load is not applied to the sensor tube 14. Hereby, since the holding member 32 is slid in the extending direction (X-direction) of the sensor tube 14, the tensile load or the compressive load resulting from thermal expansion is absorbed, and a vibration characteristic of a vibration part of the sensor tube 14 is not changed, to thereby prevent the measuring error caused by a temperature change. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vibration type measurement apparatus, and more particularly to a vibration type measurement apparatus configured to measure a flow rate or density by exciting a sensor tube to detect displacement of the sensor tube due to Coriolis force.

  For example, a Coriolis mass flow meter or a vibratory density meter is available as a vibratory measuring device that measures a physical quantity of a fluid by vibrating a pipeline supplied with the fluid. Hereinafter, the Coriolis type mass flow meter will be described.

  In this Coriolis type mass flow meter, a sensor tube through which a fluid to be measured passes is vibrated in a radial direction by a vibrator, and a displacement of the sensor tube due to a Coriolis force proportional to the flow rate is detected by a pickup. The vibration type density meter has the same configuration as the Coriolis type mass flow meter, and the sensor tube vibrates at a frequency corresponding to the density of the fluid to be measured.

  For example, in the case of a Coriolis type mass flow meter, as a conventional vibration type measuring device, a fluid is caused to flow through a pair of sensor tubes, and the pair of sensor tubes are brought close to and away from each other by the driving force of a vibrator (drive coil) (See, for example, Patent Document 1).

  Further, the vibrator and the pickup are composed of a magnet and a coil, and when a drive pulse or a positive / negative alternating voltage (AC signal) is input to the drive coil of the vibrator, it is attached to the sensor tube. The sensor tube is vibrated by applying an attractive force or a repulsive force to the drive magnet, and the displacement of the detection magnet attached to the vibrating sensor tube is detected by a detection signal output from the sensor coil (detector) of the pickup. It comes to detect.

  Since the Coriolis force acts in the vibration direction of the sensor tube and is opposite in the inlet side and the outlet side, the sensor tube is twisted, and the twist angle is proportional to the mass flow rate. Accordingly, a pickup (vibration sensor) for detecting vibration is provided at the twisted positions on the inlet side and the outlet side of the pair of sensor tubes, and the time difference between the output detection signals of both sensors is measured to measure the twist of the sensor tube, that is, the mass. The flow rate is being measured.

  However, when performing the flow measurement by providing the mass flow meter in a gas supply system that feeds compressed natural gas pressurized to a high pressure such as CNG (Compressed Natural Gas) used as a fuel for automobiles, for example, It is necessary to increase the pressure resistance of the sensor tube.

  However, if the thickness of the sensor tube is increased, the driving force of the vibrator that vibrates the sensor tube must be increased, and the resonance amplitude at the time of measurement decreases as the rigidity of the sensor tube increases. The measurement accuracy is lowered because it is easily affected by disturbances or the phase difference (twist angle) of the vibration sensors on the inflow side and the outflow side becomes small during flow rate measurement.

Therefore, in the conventional vibration type measuring device, by supplying the fluid to be measured into the storage case from the pressure supply hole of the sensor tube, the pressure inside and outside of the sensor tube is balanced and the pressure resistance of the sensor tube is increased. High pressure fluid can be measured without increasing it. (For example, refer to Patent Document 1).
JP 2004-294090 A

  In a conventional vibration type measuring apparatus, in order to increase the measurement sensitivity of the sensor tube, the sensor tube is thinned to a thickness that can withstand the pressure pulsation of the fluid to be measured. For this reason, the thinned sensor tube is measured by vibrating a linearly extending portion in a state where it is stored in the storage case, but the both ends are connected to the storage case or a flange coupled to the storage case. It is held so that it is not affected by external force.

  However, when the thinned sensor tube expands due to a temperature rise, an axial tensile load or compressive load is applied to the sensor tube due to a difference from the thermal expansion of the storage case. Thus, in a state where an axial tensile load or compressive load is applied to the sensor tube, the vibration characteristic (natural frequency) of the sensor tube changes, and for example, the flow rate of a gas having a small mass such as hydrogen. It was a cause of error when measuring.

  Therefore, an object of the present invention is to provide a vibration type measuring apparatus that solves the above problems.

  In order to solve the above problems, the present invention has the following means.

  According to the first aspect of the present invention, there is provided a storage case in which a sealed space is formed, a sensor tube that is inserted into the space and through which the measured fluid flows, and a part of the measured fluid that flows through the sensor tube. An exciter comprising a communication path to be supplied into the space, a drive magnet attached to the sensor tube, and a drive coil provided in the storage case and driving the drive magnet in a radial direction; In a vibration type measuring apparatus, comprising: a detection magnet attached to a sensor tube; and a pickup provided on an outer wall of the storage case and detecting a displacement of the detection magnet. A holding member that holds the holding portion, and a sliding hole that is formed at an end of the storage case and into which the holding member is slidably inserted. Slides the slide hole by thermal deformation of the tube, characterized in that to absorb the extending direction of the displacement of the sensor tube.

  The invention according to claim 2 is characterized in that a biasing member that biases the holding member in the extending direction of the sensor tube is provided in the sliding hole.

  The invention described in claim 3 is characterized in that a bearing is provided between the holding member and the sliding hole to enable displacement in the extending direction of the sensor tube.

  According to the first aspect of the present invention, the holding member that holds the end portion of the sensor tube slides in the sliding hole formed in the end portion of the storage case due to thermal deformation of the sensor tube, and the extending direction of the sensor tube Because it absorbs the displacement of the sensor tube, it can prevent the load due to thermal expansion and contraction due to the temperature change of the measured fluid from acting on the sensor tube, thereby suppressing the change of vibration characteristics (natural frequency) of the sensor tube For example, an error in measuring a flow rate of a gas having a small mass such as hydrogen can be suppressed.

  According to the second aspect of the present invention, since the urging member for urging the holding member in the extending direction of the sensor tube is provided in the sliding hole, the stress acting on the sensor tube is reduced with the temperature change of the fluid to be measured. As a result, changes in the vibration characteristics (natural frequency) of the sensor tube can be suppressed, and measurement errors can also be suppressed.

  According to the third aspect of the present invention, since the bearing capable of displacement in the extending direction of the sensor tube is provided between the holding member and the sliding hole, it acts on the sensor tube according to the temperature change of the fluid to be measured. Stress can be reduced, whereby changes in the vibration characteristics (natural frequency) of the sensor tube can be suppressed, and measurement errors can also be suppressed.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a longitudinal sectional view of a Coriolis mass flow meter as Example 1 of the vibration type measuring apparatus according to the present invention. FIG. 2 is a longitudinal sectional view taken along line AA in FIG. FIG. 3 is a longitudinal sectional view showing the storage case in a simplified manner in order to explain the mounting structure of the sensor tube. The vibration type measuring device can be used as a vibration type density meter and a Coriolis type mass flow meter because the mass flow rate can be obtained using the density and density of the fluid to be measured. Since the vibration type density meter and the Coriolis type mass flow meter have the same configuration, this embodiment will be described in detail when used as a mass flow meter.

  As shown in FIGS. 1 and 2, the mass flow meter 10 includes a sensor tube 14 composed of a straight pipe inserted into a sealed storage case 12, and an extending direction (X direction) of the sensor tube 14. A vibration exciter unit 16 that vibrates an intermediate portion of the sensor tube, an inflow side pickup unit 18 that detects displacement on the inflow side of the vibrating sensor tube 14, and an outflow side pickup that detects displacement on the outflow side of the vibrating sensor tube 14. Unit 20.

  The storage case 12 includes an inflow side case 22, an outflow side case 24, and a sensor part case 26 interposed between the inflow side case 22 and the outflow side case 24. The inflow side case 22 is formed of an austenitic nonmagnetic stainless steel (SUS316L), and is internally threaded with an inflow side joint 28 to which an inflow side pipe line (not shown) is connected at one end. A portion 22a is provided, and a female screw portion 22b into which the end portion of the sensor portion case 26 is screwed is provided at the other end.

  The inflow side case 22 is provided such that a through hole (sliding hole) 22c passing through between the female screw portion 22a and the female screw portion 22b extends along the center line. The through-hole 22 c is fitted with a flange 30 fixed to one end of the sensor tube 14 to regulate the mounting position of the sensor tube 14.

  As shown in FIG. 3, the flange 30 is fastened by a bolt 34 to a holding member 32 slidably inserted into the through hole 22c. Seal grooves 32c and 32d are provided on the outer periphery of the holding member 32, and a seal member 33 is mounted in the seal grooves 32c and 32d.

  Further, in the holding member 32, a central hole 32a communicating with the sensor tube 14 and a communication path 32b shifted in the radial direction from the central hole 32a penetrate through the sensor tube 14 in the extending direction (X direction). The central hole 32 a of the holding member 32 is provided so as to communicate with the inflow hole 28 a of the inflow side joint 28. The communication path 32 b of the holding member 32 is a path for supplying a part of the fluid to be measured to the sensor tube insertion hole 50. Therefore, since the inner pressure and the outer pressure of the sensor tube 14 are the same pressure, the pressure resistance is ensured even if the sensor tube 14 is thinned.

  The through hole 22c of the inflow side case 22 is provided with a step portion 22d facing the outflow side end of the holding member 32. A gap S1 is opposed to the stepped portion 22d and the outflow side end of the holding member 32, and the displacement due to the thermal contraction of the sensor tube 14 is a displacement corresponding to the length corresponding to the gap S1. Is possible.

  The inflow side end of the holding member 32 faces the end surface of the inflow side joint 28 via the gap S2, and the displacement due to the thermal expansion of the sensor tube 14 is a displacement corresponding to the length corresponding to the gap S2. It is possible. The gaps S1 and S2 are provided as play in the extending direction (X direction) of the sensor tube 14. For example, even when the low temperature fluid or the high temperature fluid is measured, the sensor tube 14 may be thermally contracted or expanded. The holding member 32 slides through the through-hole 22 c of the inflow side case 22 so that a load due to thermal stress does not act on the sensor tube 14. Therefore, measurement errors due to thermal expansion can be eliminated.

  As shown in FIG. 1, an L-shaped bracket 31 is fitted to the end of the inflow side joint 28 and fastened by a nut 29. The bracket 31 is a support leg for supporting the inflow side case 22 at a predetermined height position.

  Like the inflow side case 22, the outflow side case 24 is made of austenitic nonmagnetic stainless steel (SUS316L), and an outflow side pipe (not shown) is connected to one end. A female screw portion 24a into which the joint 36 is screwed is provided, and a female screw portion 24b into which the other end of the sensor portion case 26 is screwed is provided at the other end. Further, the outflow side joint 36 has a central hole 36 a communicating with the outflow side end of the sensor tube 14.

  The outflow side case 24 is provided such that a through hole 24c passing through between the female screw portion 24a and the female screw portion 24b extends along the center line. The through hole 24 c is fitted with a flange 38 fixed to the other end of the sensor tube 14 to restrict the mounting position of the sensor tube 14. Further, the rotation of the flange 38 is restricted by the pin 42 to the fixed plate 40 fixed to the wall surface of the through hole 24c. Further, the fixing plate 40 is provided with a central hole 40 a that communicates with the outflow side end of the sensor tube 14 and the central hole 38 a of the flange 38.

  A bracket 44 bent in an L shape is fitted to the end of the outflow side joint 36 and fastened by a nut 46. The bracket 44 is a support leg for supporting the outflow side case 24 at a predetermined height position.

  The sensor part case 26 is formed of a non-magnetic stainless steel material (SUS316L) made of austenite, and has a sensor tube insertion hole 50 extending along the center line. The sensor tube 14 is mounted at the center of the sensor tube insertion hole 50.

  Further, one end of the sensor part case 26 is provided with a male thread part 26a that is screwed into the female thread part 22b of the inflow side case 22, and the other end of the sensor part case 26 is provided with a female thread of the outflow side case 24. A male screw portion 26b to be screwed into the portion 24b is provided. The sensor case 26 is provided with vibrators 52 and 54, inflow side pickups 56 and 58, and outflow side pickups 60 and 62. The vibrators 52 and 54 are attached so as to face an intermediate position in the extending direction (X direction) of the sensor tube 14, and the inflow side pickups 56 and 58 and the outflow side pickups 60 and 62 are vibrated. They are arranged symmetrically on the inflow side and the outflow side that are separated by a predetermined distance from the vessels 52 and 54.

  In the recesses 26e and 26f provided on the upper surface 26c and the lower surface 26d of the sensor case 26, the drive coils 52a and 54a of the vibrators 52 and 54, the inflow side pickups 56 and 58, and the sensors of the outflow side pickups 60 and 62 are provided. Coils 56a, 58a, 60a and 62a are fitted. Therefore, the drive coils 52a and 54a and the sensor coils 56a, 58a, 60a, and 62a are attached so as to be close to the magnets 52b, 54b, 56b, 58b, 60b, and 62b. Furthermore, since the drive coils 52a and 54a and the sensor coils 56a, 58a, 60a and 62a are provided outside the storage case 12, the storage case 12 is filled with a combustible gas such as CNG or hydrogen. However, since there is no possibility of sparks from the electrical system, safety is ensured.

  The magnets 52b, 54b, 56b, 58b, 60b, and 62b of the vibrators 52 and 54, the inflow side pickups 56 and 58, and the outflow side pickups 60 and 62 are attached to the outer periphery of the sensor tube 14. Therefore, an intermediate portion in the extending direction of the sensor tube 14 is driven in the Z direction by the electromagnetic force from the drive coils 52a and 54a. The phase difference between the inflow side and the outflow side of the sensor tube 14 that vibrates in the Z direction is proportional to the flow rate, and the sensor coils 56a, 58a, 60a, A detection signal is output by 62a.

  Here, the configuration of the sensor tube 14 will be described. FIG. 4 is a side view showing the sensor tube 14 of the first embodiment. As shown in FIG. 4, the sensor tube 14 includes a sensing region La to which magnets 52b, 54b, 56b, 58b, 60b, and 62b are attached, an inflow side non-sensing region Lb that is an inflow side from the sensing region La, And an outflow side non-sensing region Lc which is an outflow side from the sensing region La.

  The sensing region La is also a vibration region that vibrates in the Z direction by the vibrators 52 and 54, and causes a phase difference between the inflow side and the outflow side with a displacement amount corresponding to the flow rate flowing through the sensor tube 14, so that the external Therefore, it is necessary to maintain the measurement accuracy by preventing the force from acting.

  On the other hand, the inflow-side non-sensing region Lb and the outflow-side non-sensing region Lc can also function as buffer regions that buffer external force. In the present embodiment, the inflow side non-sensing region Lb and the outflow side non-sensing region Lc are provided with bent portions 72 and 74 for absorbing tensile force or compressive force due to thermal expansion.

  Since the sensor tube 14 is formed to be thin and extend in the extending direction (X direction) so as to maintain measurement sensitivity even with a fluid having a relatively small specific gravity (for example, hydrogen). There is a tendency that the amount of thermal expansion becomes relatively large with respect to the temperature change. On the other hand, the storage case 12 that holds both ends of the sensor tube 14 has an increased pressure resistance so as to withstand the fluid pressure, and has a relatively small amount of thermal expansion with respect to a temperature change.

  Therefore, when an axial tensile load or compressive load is applied to the sensor tube 14 due to the difference in thermal expansion coefficient between the sensor tube 14 and the storage case 12, the holding member 32 allows the through hole 22 c of the inflow side case 22 to pass through the sensor tube. The sensor tube 14 is slid in the extending direction (X direction) so that no load is applied to the sensor tube 14.

  As described above, the holding member 32 slides in the extending direction (X direction) of the sensor tube 14 to absorb the tensile load or the compressive load, so that the vibration characteristics of the vibrating portion of the sensor tube 14 do not change and the temperature changes. Measurement errors due to can be prevented. Therefore, when a difference occurs in the amount of expansion / contraction between the sensor tube 14 and the storage case 12 due to a temperature change, the holding member 32 moves so that an unnecessary compressive load or tensile load is not applied to the sensing region La of the sensor tube 14. To do. Therefore, in the sensing region La, no measurement error due to the difference in thermal expansion coefficient occurs, so that it is possible to accurately perform the flow meter side even with a high temperature fluid or a low temperature fluid.

  Again, referring back to FIG. 1 and FIG. The vibrators 52 and 54 have a configuration in which drive coils 52a and 54a and magnets 52b and 54b are combined, and a magnetic field generated by alternately applying positive and negative alternating voltages (AC signals) to the drive coils 52a and 54a. On the other hand, when the magnets 52b and 54b are attracted or repelled, the middle portion of the sensor tube 14 is vibrated in the lateral direction (Z direction). In addition, the inflow side pickups 56 and 58 and the outflow side pickups 60 and 62 have a configuration in which sensor coils 56a, 58a, 60a, and 62a and magnets 56b, 58b, 60b, and 62b are combined in the same manner as the vibrators 52 and 54. When a relative displacement occurs between the sensor coils 56a, 58a, 60a, 62a and the magnets 56b, 58b, 60b, 62b, a detection signal corresponding to (displacement speed) is output.

  Each coil 52 a, 54 a, 56 a, 58 a, 60 a, 62 a is held by a coil holder 64, and each coil holder 64 is fixed to the sensor unit case 26 by a bolt 66. Further, cover members 68 and 70 for protecting the coils 52a, 54a, 56a, 58a, 60a, and 62a are attached to the upper surface 26c and the lower surface 26d of the sensor case 26.

  In addition, the inflow side case 22, the outflow side case 24, and the sensor unit case 26 have sufficient pressure resistance so that they can withstand pressure even when a high pressure fluid is supplied. Further, high-pressure fluid is introduced into the through holes 22c and 24c through which the sensor tube 14 is inserted and the sensor tube insertion hole 50, so that there is almost no pressure difference between the inside and the outside of the sensor tube 14. Yes.

  Therefore, in the mass flow meter 10, the fluid to be measured is filled in the space on the outer peripheral side of the sensor tube 14 as described above, and the pressure difference between the inside and the outside of the sensor tube 14 becomes small. By reducing the thickness, the driving force of the vibrator 16 can be reduced, and the current value flowing through the drive coils 52a and 54a of the vibrators 52 and 54 can be reduced to save power consumption. it can. Further, the sensor tube 14 vibrates in the Z direction by the exciting force of the vibrators 52 and 54. However, since the holding member 32 is fitted with a seal member 33 that seals between the inner wall of the through hole 22c on the outer periphery, the holding member 32 is fitted in the through hole 22c without any backlash in the radial direction (Z direction). It is provided so as not to affect the vibration characteristics (natural frequency) on the flow meter side.

  Furthermore, since the sensor tube 14 is made of a thin metal pipe, deformation and displacement of the sensor tube 14 due to Coriolis force is increased, and a larger output than the inflow side pickups 56 and 58 and the outflow side pickups 60 and 62 is obtained. The SN ratio can be improved and the measurement accuracy is improved.

  The drive coils 52a, 54a and the sensor coils 56a, 58a, 60a, 62a are connected to a flow rate measurement control circuit 80. The flow rate measurement control circuit 80 includes an intrinsically safe explosion-proof barrier circuit, an excitation / time difference detection circuit, a Young's modulus / A V / F conversion circuit, an output circuit, a power supply circuit, an attenuation rate detection circuit, a discrimination circuit, a control circuit (each not shown), and the like are included.

  When the flow rate is measured, in the mass flow meter 10 configured as described above, the vibrators 52 and 54 are driven by the flow rate measurement control circuit 80, and the sensor tube has a period and amplitude according to the vibration characteristics (natural frequency) of the sensor tube 14. 14 is vibrated in the vertical direction (Z direction).

  Thus, when a fluid flows through the vibrating sensor tube 14, a Coriolis force having a magnitude corresponding to the flow rate is generated. Therefore, an operation delay occurs between the inflow side and the outflow side of the straight tubular sensor tube 14, thereby causing a phase difference in output signals between the inflow side pickups 56 and 58 and the outflow side pickups 60 and 62.

  Since the phase difference between the inflow side output signal and the outflow side output signal is proportional to the flow rate, the flow rate measurement control circuit 80 calculates the flow rate based on the phase difference. Therefore, when the displacement of the sensor tube 14 is detected by the inflow side pickups 52, 54 and the outflow side pickups 56, 58, the phase difference accompanying the vibration of the sensor tube 14 is converted into a mass flow rate by the flow rate measurement control circuit 80. The

  FIG. 5 is a longitudinal sectional view showing the storage case in a simplified manner in order to explain the sensor tube mounting structure of the second embodiment. In FIG. 5, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. As shown in FIG. 5, the inflow side end of the sensor tube 14 has the same configuration as that of the first embodiment described above, and the inflow side end of the sensor tube 14 has a flange 30, a holding member 32, and a seal member. 33 is provided. Note that the inflow side holding member 32 has an outflow side end in contact with the step 22d, and the inflow side end faces the end surface of the inflow side joint 28 via the gap S2.

  The flange 38 to which the outflow side end of the sensor tube 14 is coupled includes a central hole 38a into which the sensor tube 14 is inserted and a flange 38b that fits into a recess 82e formed on the end surface of the holding member 82. Have.

  Similarly to the inflow side end, the outflow side holding member 82 inserted into the through hole (sliding hole) 24 c of the outflow side case 24 is fastened by a bolt 84. Further, seal grooves 82b and 82c are provided on the outer periphery of the holding member 82, and a seal member 83 is mounted in the seal grooves 82b and 82c. The holding member 82 has a central hole 82 a that communicates between the outflow side of the sensor tube 14 and the central hole 36 a of the outflow side joint 36.

  The holding member 82 has an inflow side end in contact with the step 24d, and an outflow side end is opposed to the end surface of the outflow side joint 36 through a gap S1.

  The holding members 32 and 82 can slide in the extending direction (X direction) of the sensor tube 14 within the range of the gaps S1 and S2. Therefore, when thermal expansion occurs in the sensor tube 14, It is possible to absorb the thermal expansion of the length corresponding to the gaps S1 and S2. Therefore, for example, when measuring a high temperature fluid, even if the sensor tube 14 is thermally expanded, the holding members 32 and 82 are slid so that a load due to thermal stress does not act on the sensor tube 14. Therefore, the measurement error accompanying the thermal expansion of the sensor tube 14 can be eliminated.

  FIG. 6 is a longitudinal sectional view showing the storage case in a simplified manner in order to explain the sensor tube mounting structure of the third embodiment. In FIG. 6, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 6, in the third embodiment, a biasing member 86 that biases the holding member 32 toward the inflow side is provided between the holding member 32 on the inflow side and the step 22d. The biasing member 86 is formed of a coil spring and is attached so as to apply a constant tension to the sensor tube 14.

  Therefore, the biasing member 86 can assist the displacement of the holding member 32 due to the thermal expansion of the sensor tube 14 when measuring a high-temperature fluid, and the sliding resistance of the holding member 32 acts as a load on the sensor tube 14. In this way, measurement errors associated with thermal expansion can be eliminated.

  FIG. 7 is a vertical cross-sectional view showing a simplified storage case in order to explain the sensor tube mounting structure of the fourth embodiment. In FIG. 7, the same parts as those in the second embodiment are denoted by the same reference numerals, and the description thereof is omitted. As shown in FIG. 7, in the fourth embodiment, an urging member 88 that urges the holding member 32 toward the inflow side is provided between the outflow side holding member 82 and the step 24e. The biasing member 88 is formed of a coil spring and is attached so as to apply a constant tension to the sensor tube 14.

  Therefore, the urging member 88 can assist the displacement of the holding member 82 accompanying the thermal expansion of the sensor tube 14 when measuring a high-temperature fluid, and the sliding resistance of the holding member 82 acts on the sensor tube 14 as a load. In this way, measurement errors associated with thermal expansion can be eliminated.

  FIG. 8 is a longitudinal sectional view showing the storage case in a simplified manner in order to explain the sensor tube mounting structure of the fifth embodiment. In FIG. 8, the same parts as those in the third embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 8, in the fifth embodiment, a biasing member 86 that biases the holding member 32 toward the inflow side is provided between the holding member 32 on the inflow side and the step 22c. In addition, seal grooves 32 c and 32 d are provided on the outer periphery of the holding member 32, and the seal member 33 and a pressure receiving ring 90 that receives pressure acting on the outer periphery of the holding member 32 are provided in the seal grooves 32 c and 32 d. It is installed. Since the seal member 33 is pressed through the pressure receiving ring 90, the seal member 33 is not greatly deformed even when the fluid to be measured has a high pressure, and the sealing performance can be maintained.

  In the fifth embodiment, the configuration of the outflow side holding member 32 has been described. However, the outflow side holding member 82 may have the same configuration.

  FIG. 9 is a longitudinal sectional view showing the storage case in a simplified manner to explain the sensor tube mounting structure of the sixth embodiment. In FIG. 9, the same parts as those in the third embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 9, in the sixth embodiment, a biasing member 86 that biases the holding member 32 toward the inflow side is provided between the holding member 32 on the inflow side and the step 22d. Further, annular protrusions 92 and 94 projecting in a trapezoidal shape are provided on the outer periphery of the holding member 32, and the outermost peripheral portion formed in a ring shape of the annular protrusions 92 and 94 is the through hole 22 c of the outflow side case 24. Is in sliding contact.

  Therefore, the holding member 32 has reduced sliding resistance with respect to the inner wall of the through hole 22c, and the X-direction displacement of the holding member 32 accompanying the thermal expansion of the sensor tube 14 can be easily performed when measuring a high temperature fluid. Therefore, the sliding error of the holding member 32 does not act as a load on the sensor tube 14, and the measurement error due to thermal expansion can be eliminated.

  In the sixth embodiment, the configuration of the outflow side holding member 32 has been described. However, the outflow side holding member 82 may have the same configuration.

  FIG. 10 is a longitudinal sectional view showing the storage case in a simplified manner to explain the sensor tube mounting structure of the seventh embodiment. FIG. 11 is a longitudinal sectional view taken along line BB in FIG. 10 and 11, the same parts as those in the fourth embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIGS. 10 and 11, in the seventh embodiment, an alignment mechanism 100 for aligning the axial center of the holding member 82 on the outflow side with the axial center of the storage case 12 in the X direction is provided. The alignment mechanism 100 is configured to adjust the position at intervals of 120 degrees on the outer periphery of the holding member 82, and is radial with respect to the through hole 24c of the outflow side case 24 (storage case 12) into which the holding member 82 is inserted. And adjustment balls 102 to 104 formed in the adjustment holes 102 to 104 and pressing balls 106 to 108 inserted into the adjustment holes 102 to 104. The pressing balls 106 and 107 are adjusted in the amount of protrusion of the holding member 82 in the axial direction by the adjusting screws 114 and 115 of the nuts 110 and 111 screwed into the adjusting holes 102 and 103. The adjustment holes 102 to 104 have an opening on the outer peripheral side that is slightly larger than the diameter of the pressing balls 106 to 108, and an inner peripheral opening is formed in a tapered shape, and a part of the pressing balls 106 to 108 is formed. It protrudes inward.

  Further, the pressing ball 108 disposed above the holding member 82 presses the outer periphery of the holding member 82 by the pressing force of the coil spring 118. The coil spring 118 is held by a spring presser 120 screwed into the adjustment hole 104, and the pressing force to the pressing ball 108 is adjusted by changing the screwing position of the spring presser 120. Then, by adjusting the screwing positions of the adjusting screws 114 and 115, the positions of the pressing balls 106 and 107 that restrict the lower position of the holding member 82 are adjusted, and the pressing that restricts the upper position on the opposite side. The ball 108 compresses the coil spring 118 pressed against the holding member 82 and receives the spring force to adjust the upper position of the holding member 82.

  Thus, the axial position of the holding member 82 is adjusted by the three pressing balls 106 to 108 of the alignment mechanism 100.

  In the seventh embodiment, the configuration of the alignment mechanism 100 that adjusts the axial center of the holding member 82 on the outflow side has been described. However, a similar alignment mechanism is provided on the holding member 32 on the inflow side. Therefore, the holding members 32 and 82 coupled to both ends of the sensor tube 14 are adjusted by the alignment mechanism 100 so that the axis coincides with the axis of the storage case 12, so that the sensor tube 14 is vibrated. It is possible to adjust so that the amplitude at the time does not deviate within the sensor tube insertion hole 50. As a result, even when the holding members 32 and 82 slide in the X direction as the sensor tube 14 is thermally expanded, the centering mechanism 100 does not cause the shaft centers of the holding members 32 and 82 to be shaken. Is stable and measurement errors associated with thermal expansion can be eliminated.

  FIG. 12 is a longitudinal sectional view showing the storage case in a simplified manner in order to explain the sensor tube mounting structure of the eighth embodiment. In FIG. 12, the same parts as those in the fourth embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 12, in the eighth embodiment, a guide mechanism 130 that guides the flange 38 to which the outflow side end of the sensor tube 14 is coupled in the extending direction (X direction) of the sensor tube 14 is provided. . The guide mechanism 130 includes a holding member 132 fastened to the flange 38 by a bolt 84, a biasing member 88 that biases the holding member 132, a ball bearing 133 that slides on the outer periphery of the holding member 132, and a ball bearing 133. A tapered movable side ring 134 fitted to the outer periphery and a tapered fixed side ring 136 fitted to the movable side ring 134 are configured. The ball bearing 133 includes a plurality of balls 133a interposed in the circumferential direction between the outer periphery of the holding member 132 and the inner periphery of the movable ring 134, and retainers 133b that hold the plurality of balls 133a in three rows. The holding member 132 has a central hole 132 a that communicates with the outflow side end of the sensor tube 14.

  The position of the stationary ring 136 on the outflow side is regulated by ring-shaped nuts 138 and 140 that are screwed into the through holes 24 c of the outlet case 24 constituting the storage case 12. The taper surface of the movable ring 134 that holds the ball bearing 133 is pressed against the taper surface of the fixed ring 136 by receiving the urging force of the urging member 88 that urges the holding member 132 to the outflow side. Therefore, when the sensor tube 14 is thermally expanded when measuring a high-temperature fluid, the flange 38 slides in the biasing direction of the biasing member 88 and absorbs the thermal expansion amount of the sensor tube 14.

  At this time, the holding member 132 integrated with the flange 38 is guided by the rolling contact of the ball bearing 133, and therefore slides in the extending direction of the sensor tube 14 with low friction.

  Therefore, in the holding member 132, the sliding resistance with respect to the inner wall of the through hole 24c is reduced by the ball bearing 133 of the guide mechanism 130, and the X of the holding member 132 accompanying the thermal expansion of the sensor tube 14 when measuring a high temperature fluid. Directional displacement can be easily performed. Therefore, in Example 8, it is comprised so that the sliding resistance of the holding member 132 may not act as a load on the sensor tube 14, and the measurement error accompanying the thermal expansion of the sensor tube 14 can be eliminated.

  Although the configuration of the outflow side holding member has been described in the eighth embodiment, the inflow side holding member may also be configured to be guided using the guide mechanism 130.

  In the above-described embodiment, the flow rate measurement is performed using a combustible gas such as CNG as the fluid to be measured. However, the present invention is not limited to this, and the present invention can be applied to measurement of other high-pressure and high-temperature fluids. Of course.

It is a longitudinal cross-sectional view of the Coriolis type mass flow meter as Example 1 of the vibration type measuring apparatus according to the present invention. It is a longitudinal cross-sectional view which follows the AA line in FIG. It is a longitudinal cross-sectional view which simplifies and shows a storage case in order to demonstrate the attachment structure of a sensor tube. It is a side view which shows the sensor tube 14 of Example 1. FIG. In order to explain the sensor tube mounting structure of Example 2, it is a longitudinal sectional view showing a storage case in a simplified manner. It is a longitudinal cross-sectional view which simplifies and shows a storage case in order to demonstrate the sensor tube attachment structure of Example 3. FIG. In order to explain the sensor tube mounting structure of Example 4, it is a longitudinal sectional view showing a storage case in a simplified manner. In order to explain the sensor tube mounting structure of Example 5, it is a longitudinal sectional view showing a storage case in a simplified manner. In order to explain the sensor tube mounting structure of Example 6, it is a longitudinal sectional view showing a storage case in a simplified manner. In order to explain the sensor tube mounting structure of Example 7, it is a longitudinal sectional view showing a storage case in a simplified manner. It is a longitudinal cross-sectional view which follows the BB line in FIG. In order to explain the sensor tube mounting structure of Example 8, it is a longitudinal sectional view showing a storage case in a simplified manner.

Explanation of symbols

10 Mass flow meter 12 Storage case 14 Sensor tube 22 Inflow side case 22c, 24c Through hole (sliding hole)
24 Outflow side case 26 Sensor part case 28 Inflow side joint 30, 38 Flange 32, 82, 132 Holding member 33, 83 Seal member 36 Outflow side joint 50 Sensor tube insertion hole 52, 54 Exciter 56, 58 Inflow side pickup 60 , 62 Outflow side pickup 86, 88 Energizing member 90 Pressure receiving ring 92, 94 Annular protrusion 100 Alignment mechanism 102 to 104 Adjustment hole 106 to 108 Press ball 114, 115 Adjustment screw 118 Coil spring 120 Spring retainer 130 Guide mechanism 133 Ball bearing 134 Movable ring 136 Fixed ring

Claims (3)

A storage case in which a sealed space is formed;
A sensor tube that is inserted into the space and through which the fluid to be measured flows;
A communication path for supplying a part of the fluid to be measured flowing through the sensor tube into the space;
A vibration exciter comprising a drive magnet attached to the sensor tube and a drive coil provided in the storage case and driving the drive magnet in a radial direction;
A pickup comprising a detection magnet attached to the sensor tube, and a detection unit provided on an outer wall of the storage case and detecting a displacement of the detection magnet;
In a vibration measuring device having
A holding member for holding an end of the sensor tube;
A sliding hole formed at an end of the storage case and slidably inserted into the holding member,
The vibration-type measuring device, wherein the holding member slides through the sliding hole by thermal deformation of the sensor tube and absorbs displacement in the extending direction of the sensor tube.   2. The vibration type measuring apparatus according to claim 1, wherein a biasing member that biases the holding member in the extending direction of the sensor tube is provided in the sliding hole. 3. The vibration type measuring apparatus according to claim 1, wherein a bearing that enables displacement of the sensor tube in an extending direction is provided between the holding member and the sliding hole.

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