• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Improves instrument error characteristics from small to large flow rate range of servo type volume flow meter. The volumetric flowmeter 1 is a pair of first and second rotors 6, 7 which flow out of a certain volume of fluid which is rotated by the fluid differential pressure and flows out in the metering chamber 3 arranged in the casing 2. The flow rate is measured from the rotation of the rotor. The servo motor 17 is connected to the first rotor 6. The pressures of the pressure detectors 10 and 11 provided at the inlet 8 and the outlet 9 of the volumetric flowmeter l are introduced into the differential pressure gauge l2 by a conduit, whereby the differential pressure is obtained and the servomechanism is applied. K (γ / 2g) V 2 (However, γ: density of the fluid under measurement, V: rotational speed of the rotor, g: gravitational acceleration, k: integer of the structural dimension of the flowmeter, and the coefficient of pipe friction) The servo motor 17 is driven so as to be. The rotation of the rotor 6 at this time is acquired by the flow rate transmitter 19 as a flow rate signal.
    公开号:KR20030090753A
    申请号:KR10-2003-7013588
    申请日:2002-05-09
    公开日:2003-11-28
    发明作者:미스미마사오；오가와유타카；오노세이고；한다류타
    申请人:가부시키가이샤 오바루；
    IPC主号:
    专利说明:

    Servo type flow meter {SERVO TYPE VOLUMETRIC FLOWMETER}
    [2] A typical volumetric flowmeter having a pair of rotors has a metering chamber and a pair of rotors rotating by fluid differential pressure in the metering chamber, and flows into the metering chamber based on the volume formed by the metering chamber and the rotor as a reference volume. It is a flowmeter which calculates a flow volume from the rotation speed of a rotor by flowing out the to-be-measured fluid according to rotation of a rotor.
    [3] That is, ideally, the volume of the measured fluid corresponding to the reference volume is discharged in proportion to the rotation of the rotor.
    [4] However, in the actual volumetric flowmeter, in order to enable the rotation of the rotor, a small gap is formed between the rotor and the metering chamber, and the rotor rotates without contacting the metering chamber.
    [5] In addition, in order for the rotor to rotate, a rotational torque that can overcome the load of a mechanical element, for example, the friction of the bearing and the load of the counter, is required. By the moment of rotation.
    [6] For this reason, when the rotor is rotated by the energy of the fluid to be measured (magnetic volumetric flowmeter), leakage occurs from the inlet side to the outlet side slightly in this gap.
    [7] BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows an example of the instrument error characteristic of a magnetic displacement flowmeter.
    [8] As shown in Fig. 1, the magnitude of the leakage is large in the range of small flow rate where the ratio of friction torque is large with respect to the moment due to the fluid differential pressure, the instrument error becomes negative, and the magnitude of the differential pressure generated in the other flow range. Also, as shown by three instrument error curves having different viscosities in FIG. 1, the instrument error characteristic changes under the influence of the viscosity of the fluid to be measured.
    [9] On the other hand, volumetric flowmeters are widely used as industrial and commercial flowmeters because they can directly measure volumetric flow rates and have high precision.
    [10] However, as described above, in principle, since the rotor rotates in the weighing chamber, the leakage caused by the gap between the weighing chamber and the rotor is a measure of a small flow rate or a measurement that pursues a higher precision. It cannot be ignored.
    [11] This leakage is also proportional to the pressure loss between the outlet inlets of the volumetric flowmeter.
    [12] The pressure loss between the inlet and outlet of the flowmeter is accurately detected so that a stable, high-precision flow rate can be measured without being influenced by physical properties such as viscosity and density of the fluid under measurement, so that the pressure loss is always zero. A flow meter that is externally supplied with a driving force to the servo motor and measures the flow rate from the rotational speed of the rotor at that time is a servo type volume flow meter.
    [13] 2 is a view showing an embodiment of the configuration of a conventional servo type volume flow meter.
    [14] 2, 1 is a volumetric flow meter, 2 is a casing, 3 is a metering chamber, 4 is a first rotor shaft, 5 is a second rotor shaft, 6 is a first rotor, 7 is a second rotor, and 8 is an inlet. , 9 is outlet, 10 is inlet pressure detector, 11 is outlet pressure detector, 12 is differential pressure gauge, 13 is distributor A, 14 is regulator, 15 is goal setter, 16 is servo motor drive circuit, 17 is servo The motor SM, 18 is a tachometer generator (TG), and 19 is a flow rate generator (PG).
    [15] The volumetric flowmeter 1 is connected to the inlet 8 and the outlet 9 so that the metering chamber 3 formed in the flow path {casing 2} and the first rotor shaft fixedly fixed to the metering chamber 3 ( 4) and a first rotor 6 and a second rotor 7 axially supported by the second rotor shaft 5, respectively.
    [16] The first rotor 6 and the second rotor 7 are opposed to each other by engaging with pilot gears (not shown) provided in the respective rotors outside the main body, that is, outside the weighing chamber 3. , The synchronous rotation is possible, and in the pilot gear of the first rotor 6 side (in this embodiment, the first rotor 6 side, but may be the second rotor 7 side), the servo motor The drive shaft of the (SM) 17 is joined.
    [17] The inlet 8 and the outlet 9 of the volumetric flowmeter 1 are provided with an inlet side pressure detector 10 and an outlet side pressure detector 11, respectively, of the inlet 8 and the outlet 9, respectively. The pressure is guided to the differential pressure gauge 12 by conduits from both pressure detection ports 10 and 11, and the pressure loss between the outlet inlets of the volumetric flowmeter 1 is measured.
    [18] A taco generator (TG) 18 is also directly connected to the drive shaft of the servo motor (SM) 17, and the servo motor (SM) 17, the taco generator (TG) 18 and the first rotor 6 The pilot gear on the side of) is vertically connected to each other.
    [19] The taco generator (TG) 18 generates a voltage value proportional to the rotation of the servo motor (SM) 17, and its output is transmitted to the servo motor (SM) 17 through the servo motor driving circuit 16. Is fed back.
    [20] The flow rate transmitter (PG) 19 is a mechanism for measuring the number of revolutions of the first rotor 6 (it may be the first rotor 6 in this embodiment, but may be the second rotor 7). And generates a pulse proportional to the flow rate.
    [21] The differential pressure signal from the differential pressure gauge 12 is converted into a voltage value Vp proportional to the differential pressure through the distributor A 13, and then input to the controller 14, and compared with the target set value from the target setter 15. The output V 1 is connected to one input terminal of the servo motor drive circuit 16.
    [22] The output V 2 of the tacho generator (TG) 18 is fed back and connected to the other input terminal of the servo motor driving circuit 16, and the pressure between the outlet inlet and outlet of the volumetric flowmeter 1 from the controller 14 is connected. The comparison value V 1 between the differential pressure signal Vp from the differential pressure gauge 12 corresponding to the loss ΔP and the target set value, and the output V of the tacho generator (TG) 18 corresponding to the rotation speed of the servo motor (SM) 17. The servo mechanism which controls the rotation of the servomotor SM 17 is formed so that two may become equal.
    [23] Although the differential pressure signal of the differential pressure gauge 12 increases in the state in which the fluid to be measured flows in the direction of the arrow, the inlet and the outlet of the flowmeter are driven by driving a servo control system composed of the servo motor drive circuit 16 and the servo motor (SM) 17. The differential pressure ΔP in between is controlled with no differential pressure. At this time, the target value of the regulator 14 is set to zero differential pressure, the rotor is forcibly rotated by the servo motor 17, and ΔP is controlled to be zero.
    [24] Conventionally, a servo type flowmeter uses a servo motor to control the rotation of a rotor so that the differential pressure ΔP on the inlet side and the outlet side of the flowmeter is ΔP = 0, as described above, regardless of the magnitude of the flow rate. Was doing. This is based on the theory that if the flow rate can be measured so that the pressure loss between the outlet inlets of the volumetric flowmeter becomes zero, the leakage amount also becomes zero.
    [25] However, when actually measuring the flow rate with a conventional servo type flow meter, a large negative gauge error in a conventional magnetic flow meter is improved in a small flow rate area, but the meter error is generally changed to a positive value. As a result, the density increases with increasing density.
    [26] The cause of the positive gauge error is that when the rotor is forcibly rotated by a servo motor in order to control the pressure loss between the outlet inlets of the volumetric flowmeter with no differential pressure, the pressure loss ΔP between the outlets of the volumetric flowmeter is Even if it is zero, the pressure on the front side in the rotational direction of the rotor in the metering chamber rises and the back side decreases, and the differential pressure ΔP i is generated on the front and back sides of the rotor in the rotational direction, so that the casing and the rotor In the gap between them, the differential pressure ΔP i causes leakage of the fluid to be measured from the outflow side to the inflow side.
    [1] TECHNICAL FIELD The present invention relates to a servo type flow meter, and more particularly, to a servo type flow meter having excellent characteristics in which the instrument error is almost zero from a small flow range to a large flow range.
    [35] BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows an example of the instrument error characteristic of a magnetic displacement flowmeter.
    [36] 2 is a view showing an embodiment of the configuration of a conventional servo type volume flow meter.
    [37] 3 is a diagram for explaining the principle of the servo type flow meter of the present invention, and is a schematic diagram showing the state of the fluid pressure distribution of the conventional servo type flow meter.
    [38] 4 is a diagram showing an example of the configuration of a servo type volume flow meter according to an embodiment of the present invention.
    [39] Fig. 5 is a diagram showing an example of instrument error characteristics by the servo type volume flow meter of the embodiment of Fig. 4.
    [40] 6 is a diagram showing an example of the configuration of a servo type volume flow meter according to another embodiment of the present invention.
    [41] FIG. 7 is a diagram showing an example of instrument error characteristics by the servo type volume flow meter of the embodiment of FIG. 6.
    [27] The present invention has been made in view of the above-described situation, and conventionally, by controlling the differential pressure ΔP on the inflow side and the outflow side of the servo type flow meter to zero, by controlling the external pressure loss ΔP e described later, ΔP i = 0 It is therefore an object of the present invention to provide a servo type flow meter capable of preventing deterioration of instrument error characteristics caused by leakage from the outflow side to the inflow side.
    [28] The servo type volumetric flowmeter of the present invention includes a metering chamber installed in a flow path, and a pair of first and second rotors that rotate by fluid differential pressure in the metering chamber and discharge a certain volume of fluid for each rotation. A servo type volume flow meter which measures a flow rate from rotation of a rotor, comprising: a servo motor connected to either of the first or second rotors, a differential pressure gauge for detecting differential pressures on the upstream side and downstream side of the metering chamber; The differential pressure signal is inputted, and the differential pressure signal is k (γ / 2g) V 2 (wherein γ: density of the fluid under measurement, V: flow velocity of the fluid, g: gravity acceleration, and k: structural dimensions of each part of the flowmeter). And a servo mechanism for driving the servo motor to be an integer determined by a tube friction coefficient.
    [29] Here, k is an integer determined by the shape and dimensions of the inlet and outlet of the flowmeter and the internal shape and dimensions, the coefficient of pipe friction, and the like, for example, expressed as k = λ (L / D) and calculated by each part (Λ: tube friction coefficient, L: tube axis length of each flowmeter, D: inside diameter of each flowmeter). In addition, V may be a flow velocity or a flow volume in a pipe, and may be a rotation speed of a rotor.
    [30] In the servo-type volume flow meter for gas according to the present invention, in the servo-type volume flow meter, the gamma is obtained from a pressure detector at one of the pressure detection ports on either the upstream side or the downstream side of the differential pressure gauge. Is obtained from a flow rate transmitter connected to either one of the first and second rotors, and multiplied by a multiplier to obtain k (γ / 2g) V 2 .
    [31] The servo-volume flowmeter for liquid according to the present invention is the servo-volume flowmeter in which the gamma is externally input and V is connected to the flow rate transmitter connected to any one of the first and second rotors. The above k (γ / 2g) V 2 is obtained by multiplying both by a multiplier.
    [32] The servo-type flowmeter of the present invention is a servo-volume flowmeter, in which a servo mechanism for driving the servomotor is assembled into a microcomputer so that the differential pressure signal is k (γ / 2g) V 2 . By realizing it.
    [33] The present invention further relates to the above-described differential pressure control, which is external from a tightening mechanism (ie, a differential pressure generating mechanism) such as a venturi tube, an orifice plate, a nozzle, and the like installed separately from the flowmeter. Servo-type volume capable of preventing deterioration of instrument error characteristics due to leakage from the inflow side to the inflow side by supplementing and controlling only the internal pressure loss by controlling the differential pressure ΔP by acquiring the pressure loss and using the signal obtained here as the control target differential pressure. It is another object to provide a flow meter.
    [34] The servo type volumetric flowmeter of the present invention includes a metering chamber installed in a flow path, a pair of first and second rotors rotating in the metering chamber and releasing a volume of fluid for each rotation, and upstream and downstream of the metering chamber. A first differential pressure gauge for detecting a differential pressure on the side, a tightening mechanism provided in series with the flow path for narrowing the flow path, a second differential pressure gauge for detecting differential pressures on the upstream side and the downstream side of the tightening mechanism, and the first differential pressure gauge And a servo mechanism which adjusts the differential pressure signal from the second differential pressure gauge to a target value and sets either of the first or second rotors according to the target value.
    [42] In general, when a fluid flows through a volumetric flowmeter, a pressure drop of ΔP occurs at a differential pressure detection position sufficiently separated from the rotor.
    [43] ΔP = ΔP i + ΔP e
    [44] Is established. Here, ΔP i is the pressure loss consumed to rotate the rotor and is referred to as internal pressure loss because it is directly involved in the leakage inside the flowmeter. In addition, ΔP e is a pressure loss consumed by the fluid to flow through the flowmeter, and is referred to as external pressure loss because it does not directly participate in leakage.
    [45] In a volumetric flowmeter incorporating a pair of rotors, with respect to the differential pressure ΔP i before and after the rotor involved in the leakage inside the flowmeter, the leakage amount Δq in the flowmeter per unit time is μ, and the viscosity of the fluid and Q flow rate. By
    [46] Δq = k a · (ΔP i / μ) + k b · Q ‥‥ (1)
    [47] Represented by
    [48] However, k a and k b are integers determined by the shapes of the rotor and the casing. Therefore, the amount of leakage inside the flowmeter per unit time is divided into terms proportional to the differential pressure before and after the rotor rotation and proportional to the flow rate and inversely proportional to the viscosity of the fluid.
    [49] Here, if I is the indication amount of the examinee to be calibrated, Q is the true value of the standard machine, the instrument error E is
    [50] E = ((I-Q) / Q) × 100 (%) ‥‥ (2)
    [51] Represented by From the relationship with the leakage amount Δq inside the flowmeter,
    [52] I-Q =-Δq ‥‥ (3)
    [53] Is established. Therefore, from the formulas (1), (2) and (3), the instrument error E is
    [54] E =-(Δq / Q) =-(k a (ΔP i / (μQ)) + k b ) ‥‥ (4)
    [55] It can be represented by. In this case, in order to zero the instrument error E, if the differential pressure ΔP i after the rotation of the rotor of Formula (1) is set to zero, the amount of leakage inside the flowmeter is also zero, and the flow rate is proportionally proportional to the rotational speed. Also appears near zero. The second term in equation (4) can be ignored by changing the meter factor.
    [56] Therefore, in order to zero the instrument error of a servo type volume flow meter, it is good to control the differential pressure in the position which detects pressure loss (D) P to internal pressure loss (DELTA) P i = 0. That is, by applying the driving force externally so that the control target differential pressure and the external pressure loss ΔP e are equal, the internal pressure loss ΔP i becomes zero, so that the leakage inside the flowmeter is eliminated and inevitably there is no leakage, that is, the instrument error. Zero flow meters can be implemented.
    [57] 3 is a diagram for explaining the principle of the servo type flow meter of the present invention, and is a schematic diagram showing the state of the fluid pressure distribution of the conventional servo type flow meter.
    [58] As described above, when the differential pressure ΔP on the inflow side and the outflow side is controlled to zero in the servo type volume flow meter, the differential pressure ΔP i is generated on the front and rear surfaces of the rotor in the rotational direction. Due to the differential pressure ΔP i , the leakage amount leaking from the outlet side to the inlet side in the gap between the casing and the rotor increases with the increase in pressure and flow rate correlated with the density γ of the fluid to be measured and the rotational speed V of the rotor. The instrument error is a plus.
    [59] In the servo type flow meter according to one embodiment of the present invention, in consideration of the external pressure loss ΔP e , ΔP = P i + ΔP without controlling the differential pressure ΔP on the inflow side and the outflow side of the servo type flow meter to zero. In e , the pressure loss ΔP i before and after the rotor, i.e., the internal pressure loss ΔP i = O, is controlled so that the inlet pressure is increased by ΔP = ΔP e = k (γ / 2g) V 2 . By controlling the volumetric flowmeter, the internal pressure loss ΔP i = O between the front side and the back side of the rotational direction of the rotor is set to eliminate leakage of the fluid to be measured from the gap between the casing and the rotor.
    [60] Where k is an integer determined by the internal shape, dimensions and pipe friction coefficient of the flow meter, for example, k = λ (L / D) (λ: tube friction coefficient, L: tube axis length inside the flowmeter, D: flowmeter Inside diameter). Although V is the rotational speed of the rotor, the flow rate or the flow rate in the pipe may be used.
    [61] 4 is a conceptual diagram showing an example of the configuration of a servo type volume flow meter according to an embodiment of the present invention.
    [62] In the figure, 1 is a volumetric flow meter, 2 is a casing, 3 is a metering chamber, 4 is a first rotor shaft, 5 is a second rotor shaft, 6 is a first rotor, 7 is a second rotor, 8 is an inlet, 9 Is outlet, 10 is inlet pressure detector, 11 is outlet pressure detector, 12 is differential pressure gauge, 13 is distributor A, 14 is regulator, 16 is servo motor driving circuit, 17 is servo motor (SM), 18 is taco Generator TG and 19 are flow rate generators PG, which are common to the components of the conventional servo type volumetric flowmeter shown in FIG. 2 and basically have the same function (detailed description is omitted), and the same reference numerals are used. Attaching. The first rotor 6 or the second rotor 7 is rotated by the servo motor 17 in the weighing chamber 3.
    [63] In the servo type volume flow meter of this embodiment, the F / V converter 20, the linearizer 21, the pressure gauge 22, and the distributor B 23 instead of the target setter 15 of the conventional apparatus in FIG. ), A multiplier 24 is provided.
    [64] The F / V converter 20 converts a pulse signal representing the flow rate from the flow rate transmitter (P.G) 19 into an analog voltage proportional to its frequency, and outputs a signal corresponding to the rotational speed V of the rotor.
    [65] The linearizer 21 squares the output of the F / V converter 20 and outputs a signal V 2 corresponding to the square of the rotational speed V of the rotor.
    [66] The pressure gauge 22 converts the pressure at the inflow side pressure detection port 10 (or the outflow side pressure detection port 11) into a voltage signal corresponding to the fluid pressure P.
    [67] The distributor B 23 converts the voltage signal corresponding to the fluid pressure P from the pressure gauge 22 into a voltage signal corresponding to the fluid density γ proportional to the fluid pressure P when the fluid to be measured is a gas. do.
    [68] In the case of a liquid, since the fluid density γ does not change with the fluid pressure P, but is determined according to the type of liquid, the pressure gauge 22 is unnecessary and is directly external to the multiplier 24 and the external multiplier ( Enter the value according to the liquid under measurement in 24).
    [69] The multiplier 24 multiplies the signal V 2 corresponding to the square of the rotational speed V of the rotor from the linearizer 21 and the signal corresponding to the density γ from the distributor B 23. The signal Vs corresponding to (k 0 · γ · V 2 ) is output as the target set value of the controller 14. On the other hand, k 0 is an integer, and k 0 = k (1 / 2g) = λ (L / D) · (1 / 2g).
    [70] The signal Vp corresponding to the differential pressure ΔP on the inlet side and the outlet side of the flowmeter is input to the other terminal of the controller 14 as in the conventional apparatus. In the controller 14, the signal Vs from the multiplier 24 is input. Compared with, the signal V 1 corresponding to Vp-Vs = (ΔP-ko.γV 2 ) is output to one input terminal of the servo motor drive circuit 16.
    [71] The other input terminal of the servo motor drive circuit 16 is fed back with a voltage V 2 proportional to the rotational speed of the servo motor SM 17 from the tacho generator TG 18 and connected to the controller ( The servo mechanism is operated to be equal to the signal V 1 from 14) to control the rotation of the servo motor (SM) 17.
    [72] In the state where the fluid to be measured flows in the direction of the arrow, the external pressure generated inside the flowmeter according to the rotational speed V of the rotor without controlling the differential pressure ΔP on the inflow side and the outflow side of the servo-type flowmeter in the conventional manner to zero. By controlling the servo volumetric flowmeter so as to increase the pressure on the inflow side by the pressure loss ΔP e = k (γ / 2g) V 2 , the differential pressure ΔP i on the front side and the back side in the rotational direction of the rotor is zero.
    [73] Accordingly, in the conventional servo type volume flow meter, the differential pressure in the reverse direction between the differential pressure ΔP i between the front and rear surfaces of the rotor generated by controlling the differential pressure ΔP on the inflow side and the outflow side to zero can be eliminated. As a result, less leakage due to backflow from the gap between the casing and the rotor could be achieved.
    [74] Fig. 5 is a diagram showing an example of instrument error characteristics by the servo type flow meter of the present embodiment, in which P 1 , P 2 , and P 3 each represent a fluid pressure of the fluid under measurement.
    [75] As shown in Fig. 5, the instrument error characteristic of the servo type volume flow meter according to the present embodiment is linear in that the instrument error is almost zero, from the small flow region to the large flow region, regardless of the magnitude of the pressure of the fluid to be measured. It can be seen that it exhibits excellent characteristics.
    [76] The rotational speed V of the rotor is controlled at a value calculated at the average speed because the speed is different at the tip of the rotor and the root of the rotor, or in consideration of the gap between the casing and the tip of the rotor. By controlling at a differential pressure of a value close to the value calculated at the speed of the former tip, the accuracy can be improved further.
    [77] The above is a case where the control system is configured in a hard configuration. However, when assembling the control system with a microcomputer, the above-described operation processing may be performed by software and assembled. The density can be set simply by selecting the name of the fluid to be measured.
    [78] On the other hand, when the temperature of the fluid changes, the density changes due to expansion of the measurement fluid, etc., so that the measurement of the temperature of the measurement fluid and density correction are performed, thereby enabling more accurate flow rate measurement.
    [79] As described above, according to the servo type flow meter of the present embodiment, the front side of the rotor in the rotational direction is controlled by controlling the servo type flow meter so as to increase the pressure on the inflow side by the differential pressure generated according to the rotational speed of the rotor. Since the differential pressure ΔP i = 0 on the back side and the back side can be eliminated, leakage from the gap between the casing and the rotor can be eliminated, so that high-precision flow rate measurement is possible. This servo type volume flow meter can be applied to both gas and liquid.
    [80] In the servo type flow meter according to the above-described embodiment, in consideration of the external pressure loss ΔP e , ΔP = P i + ΔP e without controlling the differential pressure ΔP on the inflow side and the outflow side of the servo volume flow meter to zero. Since the pressure loss ΔP i before and after the rotor, i.e., the internal pressure loss ΔP i = 0, is controlled by ΔP = ΔP e = k (γ / 2g) V 2 = C · γ · Q 2 . By controlling the servo volumetric flowmeter so as to increase the internal pressure loss ΔP i = 0 between the front side and the back side of the rotational direction of the rotor, it is possible to eliminate the leakage of the fluid to be measured from the gap between the casing and the rotor. It is possible. Here, k and C are integers determined by the internal shape, dimensions, pipe friction coefficient, etc. of the flowmeter, and are displayed using, for example, λ (L / D) (λ: pipe friction coefficient, L: inside the flowmeter). Tube length, D: inner diameter of the flowmeter). In addition, as mentioned above, although V was made into the rotational speed of a rotor, the flow velocity in a pipe | tube, or the flow volume Q may be used.
    [81] The servo type volume flow meter according to another embodiment of the present invention is characterized in that, in the above-described differential pressure control, the external pressure loss is reduced from a tightening mechanism (ie, a differential pressure generating mechanism) such as a venturi tube, an orifice plate, a nozzle, and the like installed separately from the flow meter. Only the internal pressure loss is compensated for by controlling the differential pressure P as a control target differential pressure.
    [82] FIG. 6 is a view showing an example of the configuration of a servo type flow meter in accordance with another embodiment of the present invention, wherein 1 is a volumetric flow meter, 2 is a casing, 3 is a weighing chamber, and 4 is a first rotation. Magnetic shaft, 5 is the second rotor shaft, 6 is the first rotor, 7 is the second rotor, 8 is the inlet, 9 is the outlet, 10 is the inlet pressure detector, 11 is the outlet pressure detector, 12 is the first rotor It is a primary pressure gauge, these are common to the components of the conventional servo type volume flow meter shown in FIG. 2, and basically have the same function (the detailed description is omitted), and the same reference numerals are assigned. The first rotor 6 or the second rotor 7 is rotated by the servo motor 17 in the metering chamber 3.
    [83] In the servo type volume flow meter of this embodiment, a tightening mechanism 31 and a second differential pressure gauge 32 are provided instead of the target setter 15 of the conventional apparatus in FIG. In the present embodiment, the differential pressure signal from the first differential pressure gauge 12 and the differential pressure signal from the second differential pressure gauge 32 are input to the controller 14, and the differential pressure signal from the first differential pressure gauge 12 and the second differential pressure signal 12 are input. The first rotor 6 or the second rotor 7 is driven by a servo mechanism in accordance with the target value, adjusted to the differential pressure signal from the differential pressure gauge 32 to be a target value. In this embodiment, a servo motor driving circuit 16, a servo motor (SM) 17, and a tacho generator (TG) 18 are provided as a servo mechanism, and the above-described target value (following target value) is used for the servo motor driving circuit. Instructed at 16, the servo motor (SM) 17 is driven to drive the rotor 6 or 7. However, in this embodiment, the target value is assumed to be amplified by the amplifier 33 to adjust the differential pressure signal from the second differential pressure gauge 32.
    [84] A tightening mechanism (differential pressure generating mechanism) 31 refers to a mechanism for generating a differential pressure by narrowing the flow path by attaching it to the middle of the flow path such as an orifice plate, a nozzle, a venturi tube, and the like. In this embodiment, the fastening mechanism 31 is provided in series with the flow path, and is further provided in the position separated from the measurement chamber 3. In the second differential pressure gauge 32, a differential pressure signal is obtained by measuring the differential pressure ΔP e (corresponding to Cp γx · Qx 2 ) with pressure detection ports provided respectively on the upstream side and the downstream side of the tightening mechanism 31. Here, Cp is a constant determined by a tightening ratio in a tightening mechanism such as an orifice, γx is a fluid density, and Qx is a flow rate.
    [85] The differential pressure signal from the second differential pressure gauge 32 is first input to the amplifier 33. The amplifier 33 amplifies, for example, the differential pressure signal (corresponding to the differential pressure ΔP e = Cp · γx · Qx 2 ) by k = Co / Cp times. On the other hand, C 0 is an integer determined by the structure, dimensions, and the like of the tightening mechanism.
    [86] The other terminal of the regulator 14 is inputted with a signal Vp (corresponding to the process value PV) corresponding to the differential pressure ΔP on the inlet side and the outlet side of the flowmeter, as in the conventional apparatus in FIG. In 14), the signal V 1 (corresponding to the target value described above) corresponding to (Vp-Vs) is compared with the signal Vs (corresponding to the reference value SV) from the amplifier 33, and the servo motor drive circuit 16 It is output to one input terminal of).
    [87] The other input terminal of the servo motor drive circuit 16 is fed back with a voltage V 2 proportional to the rotation speed of the servo motor SM 17 from the tacho generator TG 18 and connected to the controller. The servo mechanism is operated so as to be equal to the signal V 1 from (14) to control the rotation of the servo motor (SM) 17. By this control, the differential pressure ΔP 1 on the front side and the rear side in the rotational direction of the rotor is zero.
    [88] Therefore, by inserting a tightening mechanism such as an orifice plate, the pressure loss in the flow path increases, but it is not necessary to attach the fluid density in advance, and the temperature pressure compensation of the fluid density is unnecessary, and the linearizer, the multiplier, etc. are unnecessary and simplified control. You can build a system. By this control system, in the conventional servo type flow meter, the differential pressure ΔP 1 between the front and rear surfaces of the rotor generated by controlling the differential pressure ΔP on the inflow side and the outflow side to zero can be eliminated. Therefore, less leakage due to backflow from the gap between the casing and the rotor can be achieved. In particular, the case where the density of the fluid is changed and the density is not stable is effective, and the shift of the instrumentation error due to the viscosity of the fluid to be measured as shown in Fig. 1 need not be taken into consideration.
    [89] Fig. 7 is a diagram showing an example of instrument error characteristics by the servo type volume flow meter of this embodiment.
    [90] Fig. 7 shows the result of the instrument error test (30.9 ° C, 1.12 mPa · s) by setting the external pressure loss obtained by calculation, and includes the basic accuracy of the configured electric meter and the like in the range of several times the general flow range. It can be seen that excellent instrument error precision of ± 0.1% or more can be realized.
    [91] As described above, the servo-type volume flow meter according to the present embodiment has a pair of first and second rotors 6 and 7 which discharge a constant volume of fluid every revolution, and drives any of them. The flow rate is measured from the rotational speed of the servo motor. The first differential pressure signal is obtained by the differential pressure gauge 12 between the inlet 8 and the pressure detection ports 10, 11 provided at the outlet 9. On the other hand, the tightening mechanism 31 is provided in the middle of the flow path, and the differential pressure Pe is measured by the pressure detecting ports provided on the upstream and downstream sides by the differential pressure gauge 32 to obtain the second differential pressure signal. The first differential pressure signal is adjusted to the second differential pressure signal to be a target value, and the first rotor 6 or the second rotor 7 is driven by the servo motor 17 in accordance with the target value.
    [92] According to the present embodiment, the differential pressure measured before and after the differential pressure generating mechanism such as the tightening mechanism is amplified to a desired value by an amplifier to obtain a differential pressure control target value, and the differential pressure between the inlet and outlet of the flowmeter is controlled to become the differential pressure control target value. Since the differential pressure on the front side and the back side of the rotor in the rotational direction becomes zero, leakage from the gap between the casing and the rotor can be eliminated, so a simple system configuration enables highly accurate flow measurement over a wide flow range. Become. Moreover, it is especially effective when the component of the fluid changes and the density is unstable, and the instrument error due to the viscosity of the fluid to be measured does not have to be taken into consideration.
    [93] According to the present invention, the differential pressure ΔP 1 = 0 on the front side and the back side of the rotor in the rotational direction of the rotor is controlled by controlling the servo volumetric flowmeter so as to increase the pressure on the inflow side by the differential pressure generated according to the rotational speed of the rotor. Since leakage in the gap between the casing and the rotor can be eliminated, high-precision flow measurement can be performed. This servo type volume flow meter can be applied to both gas and liquid.
    [94] Further, according to the present invention, the differential pressure measured before and after the differential pressure generating mechanism such as a tightening mechanism is amplified to a desired value by an amplifier to obtain a differential pressure control target value, and the differential pressure between the inlet and outlet of the flowmeter is controlled to be the differential pressure control target value. As a result, the differential pressure on the front side and the back side of the rotor in the rotational direction becomes zero, and leakage from the gap between the casing and the rotor can be eliminated. Thus, a simple system configuration allows high precision flow measurement over a wide flow range. It becomes possible. Moreover, it is especially effective when the component of the fluid changes and the density is unstable, and the instrument error due to the viscosity of the fluid to be measured does not have to be taken into consideration.
    权利要求:
    Claims (5)
    [1" claim-type="Currently amended] A metering chamber installed in the flow path and a pair of first and second rotors which rotate by fluid differential pressure in the metering chamber and discharge a certain volume of fluid at each rotation, and measure the flow rate from the rotation of the rotor. A servo type volume flow meter, comprising: a servo motor connected to one of the first and second rotors, a differential pressure gauge for detecting differential pressures on the upstream side and the downstream side of the weighing chamber, and a differential pressure signal of the differential pressure gauge; The differential pressure signal is k (γ / 2g) V 2 (wherein γ is the density of the fluid under test, V is the flow rate of the fluid, g is the acceleration of gravity, and k is an integer determined by the structural dimension of the flow meter, and the coefficient of pipe friction) A servo type volume flow meter, comprising: a servo mechanism for driving the servo motor as much as possible.
    [2" claim-type="Currently amended] 2. The pressure detector according to claim 1, wherein the gamma is obtained from a pressure detector at any one of the pressure detection ports upstream or downstream of the differential pressure gauge, and the V is connected to either the first or second rotor. A servo-type volume flow meter obtained by obtaining a flow rate transmitter and multiplying both by a multiplier to obtain k (γ / 2g) V 2 .
    [3" claim-type="Currently amended] The method of claim 1, wherein the gamma is input from the outside, and the V is obtained from a flow rate transmitter connected to either one of the first or second rotors, and the k is multiplied by a multiplier. ) Servo type flow meter, characterized by obtaining V 2 .
    [4" claim-type="Currently amended] 4. A program according to any one of claims 1 to 3, wherein a servo mechanism for driving the servo motor is realized by a program assembled in a microcomputer so that the differential pressure signal becomes k (γ / 2g) V 2. Servo type flow meter, characterized in that.
    [5" claim-type="Currently amended] A metering chamber installed in the flow path, a pair of first and second rotors rotating in the metering chamber and releasing a volume of fluid for each rotation, and a first pressure detecting upstream and downstream of the metering chamber; A differential pressure gauge, a tightening mechanism provided in series with the flow path to narrow the flow path, a second differential pressure gauge for detecting differential pressures on the upstream and downstream sides of the tightening mechanism, and a differential pressure signal from the first differential pressure gauge; A servo type volume flow meter, comprising: a servo mechanism that adjusts to a differential pressure signal from a differential pressure gauge to a target value, and drives one of the first and second rotors according to the target value.
    类似技术:
    公开号 | 公开日 | 专利标题
    US10606285B2|2020-03-31|System for and method of monitoring flow through mass flow controllers in real time
    US6092409A|2000-07-25|System for validating calibration of a coriolis flowmeter
    EP1554550B1|2015-04-08|Detection and measurement of two-phase flow
    US5861561A|1999-01-19|Bypass type coriolis effect flowmeter
    US4507976A|1985-04-02|Flow meter with hall effect sensor and method
    JP2790260B2|1998-08-27|Apparatus and method for measuring the flow of a two or three phase fluid using one or more momentum and one volume flow meter
    US20140131277A1|2014-05-15|Closed Loop Flow Control Of A HPLC Constant Flow Pump To Enable Low-Flow Operation
    US7770459B2|2010-08-10|Differential pressure diagnostic for process fluid pulsations
    US6564824B2|2003-05-20|Mass flow meter systems and methods
    JP2787785B2|1998-08-20|Flowmeter and flow measurement method
    US7258024B2|2007-08-21|Simplified fluid property measurement
    US6721669B2|2004-04-13|Method and device for measuring the volumetric flow of a fluid
    AU2009351106B2|2013-05-09|Method and apparatus for determining a zero offset in a vibrating flow meter
    US9562796B2|2017-02-07|Absolute and differential pressure transducer
    CA2838987C|2016-08-30|Method and apparatus for determining differential flow characteristics of a multiple meter fluid flow system
    US6591697B2|2003-07-15|Method for determining pump flow rates using motor torque measurements
    CA2277381C|2007-09-18|Gas turbine meter
    DE69811044T2|2004-10-28|Method for measuring the viscosity of a fluid
    CA2647242C|2015-08-11|Single and multiphase fluid measurements
    EP0122100A1|1984-10-17|Fluid density and mass flow measurement
    AU2009351105B2|2013-04-18|Method and apparatus for determining and compensating for a change in a differential zero offset of a vibrating flow meter
    US6151557A|2000-11-21|Friction flowmeter with improved software
    US20060123920A1|2006-06-15|System and method for measuring flow
    US7519483B2|2009-04-14|Unsteady flow meter
    EP2154489A1|2010-02-17|Heat flowmeter
    同族专利:
    公开号 | 公开日
    KR100536432B1|2005-12-16|
    EP1403626A1|2004-03-31|
    WO2002095340A1|2002-11-28|
    EP1403626A4|2006-11-02|
    EP1403626B1|2011-12-07|
    CN100468012C|2009-03-11|
    TW561247B|2003-11-11|
    CN1511250A|2004-07-07|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2001-05-21|Priority to JPJP-P-2001-00150430
    2001-05-21|Priority to JP2001150430A
    2001-08-03|Priority to JP2001236785A
    2001-08-03|Priority to JPJP-P-2001-00236785
    2002-05-09|Application filed by 가부시키가이샤 오바루
    2002-05-09|Priority to PCT/JP2002/004539
    2003-11-28|Publication of KR20030090753A
    2005-12-16|Application granted
    2005-12-16|Publication of KR100536432B1
    优先权:
    申请号 | 申请日 | 专利标题
    JPJP-P-2001-00150430|2001-05-21|
    JP2001150430A|JP3331212B2|2000-09-07|2001-05-21|Servo displacement meter|
    JP2001236785A|JP3494634B2|2001-08-03|2001-08-03|Servo type positive displacement flowmeter|
    JPJP-P-2001-00236785|2001-08-03|
    PCT/JP2002/004539|WO2002095340A1|2001-05-21|2002-05-09|Servo type volumetric flowmeter|
    [返回顶部]