Measuring equipment

Abstract

To provide a measuring apparatus capable of improving measurement accuracy of a flow rate of a fluid flowing in a flow channel.SOLUTION: A measuring apparatus 1 contributes to measurement of a flow rate of a fluid flowing in a flow channel F. The measuring apparatus 1 includes: a plurality of pressure sensor portions 10 respectively arranged at a plurality of locations of the flow channel F; a single reference power supply 20 that provides a common voltage reference to each of the plurality of pressure sensor portions 10; a single counter circuit 40 that counts in common a frequency of an output signal output from each of the plurality of pressure sensor portions 10, the frequency being for calculating the pressure of the fluid at a corresponding location, the pressure being associated with the flow rate; and a single excitation source 50 that provides a frequency reference to the counter circuit 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a measurement device. [Background technology]

[0002] A conventional technique related to a measuring device for measuring the flow rate of a fluid flowing through a flow path using a plurality of pressure gauges respectively disposed at a plurality of locations in the flow path has been known. Such pressure gauges measure the pressure of the fluid at the locations where they are installed based on a sensor element having a diaphragm and an oscillator.

[0003] For example, Patent Document 1 discloses a vibration sensor measurement device that realizes stable vibration of a vibrator, improved measurement accuracy of physical quantities by removing noise, and improved yield of vibrators. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-210371 Summary of the Invention [Problem to be solved by the invention]

[0005] In a conventional measurement device for measuring the flow rate of a fluid, each of the multiple pressure gauges has an individual diaphragm and vibrator, as described in Patent Document 1. In addition, each of the multiple pressure gauges also has an individual reference power supply for providing a bias voltage applied between the vibrator and the fixed electrode. Furthermore, each of the multiple pressure gauges also has an individual counter circuit for counting the frequency of an output signal output from a sensor element having a vibrator, and an excitation source for providing a frequency reference to the counter circuit. As a result, individual differences in the characteristics of each pressure gauge increase, reducing the accuracy of flow rate measurement.

[0006] An object of the present disclosure is to provide a measurement device that can improve the accuracy of measuring the flow rate of a fluid flowing through a flow path. [Means for solving the problem]

[0007] In some embodiments, a measurement device contributes to measuring the flow rate of a fluid flowing through a flow path, and includes a plurality of pressure sensor units respectively positioned at a plurality of locations in the flow path, a single reference power supply providing a common voltage reference to each of the plurality of pressure sensor units, a single counter circuit that commonly counts the frequency of an output signal output from each of the plurality of pressure sensor units, the frequency being associated with the flow rate, to calculate the pressure of the fluid at the corresponding location, and a single excitation source that provides a frequency reference to the counter circuit.

[0008] This makes it possible to improve the accuracy of measuring the flow rate of a fluid flowing through a flow path. The measurement device has a single reference power supply, a single counter circuit, and a single excitation source, which can be commonly arranged for multiple pressure sensor units. Therefore, the measurement device enables synchronized simultaneous measurements for each pressure sensor unit.

[0009] In addition, the measurement device can reduce individual differences in the characteristics of each pressure sensor unit and improve the accuracy of flow rate measurement. For example, by providing a common reference power supply for each pressure sensor unit, the relative accuracy of the output between sensor elements based on the reference power supply is improved. For example, by providing a common excitation source for each pressure sensor unit, the relative quantization error caused by the excitation source is reduced. Furthermore, the long-term stability caused by the reference power supply and excitation source is improved, thereby suppressing the deterioration of relative accuracy over time.

[0010] The measurement device can also contribute to reducing the board area by sharing the electrical circuitry for multiple pressure sensor units, making it easier to miniaturize the measurement system including the measurement device.

[0011] In one embodiment, the measurement device may further include a single calculation circuit that calculates the pressure of the fluid at the corresponding location based on the frequency counted by the counter circuit.

[0012] This allows the measurement device to have multiple pressure sensor units and a calculation circuit arranged within the same device, thereby enabling simultaneous measurements synchronized for each pressure sensor unit, while reducing the space occupied by the measurement system including the measurement device and contributing to its miniaturization.

[0013] In one embodiment, the arithmetic circuit may calculate the flow rate based on a pressure difference of the fluid among the plurality of locations, thereby enabling the measurement device to accurately measure the flow rate of the fluid flowing through the flow path.

[0014] The measurement device in one embodiment may further include a communication unit that transmits the calculation results of the calculation circuit to an external device.

[0015] This allows the measurement device to provide the calculation results of the arithmetic circuit to the external device as information as needed. Therefore, the measurement device can also display the calculation results as information on the external device and prompt the user to check the information. The measurement device can also display measurement parameters calculated by the arithmetic circuit, such as pressures, pressure differences, and flow rates, on the external device and prompt the user to check the measurement parameters.

[0016] In one embodiment of the measuring device, each of the plurality of pressure sensor units may have a diaphragm that receives the pressure of the fluid, and a sensor element that outputs the output signal at the frequency corresponding to the pressure received by the diaphragm.

[0017] This allows the measurement device to output an output signal having a frequency corresponding to the pressure received by the diaphragm from each of the multiple pressure sensor units, and therefore the measurement device can calculate the flow rate of the fluid based on the pressure difference of the fluid between multiple points in the flow path.

[0018] In one embodiment of the measuring device, the sensor element may have two vibrators that output the output signal and one diode that outputs a voltage proportional to the ambient temperature. This allows the measuring device to receive information on the two resonant frequencies and the diode on-voltage in an arithmetic circuit and calculate the pressure for each pressure sensor unit based on equations (1) to (3) described below.

[0019] In one embodiment, the plurality of pressure sensor units may include a first pressure sensor unit and a second pressure sensor unit, and the single counter circuit may commonly count a first frequency for calculating a first pressure of the fluid at a first location where the first pressure sensor unit is disposed, and a second frequency for calculating a second pressure of the fluid at a second location where the second pressure sensor unit is disposed. This allows the measurement device to have two pressure sensor units within a single device and to measure two pressures simultaneously. [Effects of the Invention]

[0020] According to the present disclosure, it is possible to provide a measurement device that can improve the accuracy of measuring the flow rate of a fluid flowing through a flow path. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of the configuration of a measurement device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a block diagram showing an example of a more detailed configuration of the measurement device of FIG. 1. [Figure 3] FIG. 10 is a schematic diagram illustrating an example of the configuration of a measurement device according to a modified example of the present disclosure. [Figure 4] FIG. 1 is a schematic diagram showing a schematic configuration of a conventional measurement system. DETAILED DESCRIPTION OF THE INVENTION

[0022] The background and problems of the prior art will now be described in more detail.

[0023] FIG. 4 is a schematic diagram showing the general configuration of a conventional measurement system 100. The measurement system 100 measures the flow rate of a fluid flowing through a flow path F. The flow path F includes a first flow path F1, a second flow path F2, and a third flow path F3. The first flow path F1, the second flow path F2, and the third flow path F3 represent flow paths for fluids such as gas and liquid. The first flow path F1, the second flow path F2, and the third flow path F3 differ from one another in terms of shape, etc. Therefore, the flow path resistances of these flow paths differ from one another. The second flow path F2 is a flow path with a known flow path resistance, through which a fluid flows at a known flow rate when a pressure difference between the left and right ends of the second flow path F2 occurs, for example.

[0024] The measurement system 100 has a first pressure gauge 110 and a second pressure gauge 120 at both ends of a second flow path F2 having a known flow path resistance in order to measure the flow rate of the fluid flowing through the flow path F. The measurement system 100 measures the pressure difference between both ends of the second flow path F2 using the first pressure gauge 110 and the second pressure gauge 120. The measurement system 100 measures the flow rate of the fluid flowing through the second flow path F2 based on the measured pressure difference and the known flow path resistance of the second flow path F2.

[0025] The measurement system 100 arranges two pressure gauges required for measuring the flow rate of the fluid, one at each end of the second flow path F2, and calculates the pressure difference between the obtained pressures using a calculator 130 arranged separately from the first pressure gauge 110 and the second pressure gauge 120. The measurement system 100 transmits the calculation results obtained by the calculator 130 to an external device connected so as to be able to communicate with the measurement system 100 as needed.

[0026] The first pressure gauge 110 and the second pressure gauge 120 are used to measure the pressure difference between the left and right ends of the second flow path F2. The first pressure gauge 110 has, in order from the first flow path F1 side, a diaphragm 111, a sensor element 112, a reference power supply 113, an amplifier 114, a counter circuit 115, an excitation source 116, and a calculation circuit 117. The second pressure gauge 120 has, in order from the third flow path F3 side, a diaphragm 121, a sensor element 122, a reference power supply 123, an amplifier 124, a counter circuit 125, an excitation source 126, and a calculation circuit 127.

[0027] The diaphragm 111 bends with a predetermined tension when subjected to a first pressure P1 from the fluid flowing through the first flow path F1. The amount of deformation of the diaphragm 111 depends on the first pressure P1. The sensor element 112 outputs, as an output signal, a current with a resonant frequency that depends on the amount of deformation of the diaphragm 111, i.e., on the first pressure P1. The resonant frequency of the current changes in response to changes in the first pressure P1 of the fluid flowing through the first flow path F1.

[0028] The reference power supply 113 applies a bias voltage to the sensor element 112 to cause the sensor element 112 to output a current having such a resonance frequency. The amplifier 114 amplifies the output signal from the sensor element 112. The counter circuit 115 counts the resonance frequency of the output signal output from the sensor element 112 and amplified by the amplifier 114. The excitation source 116 provides a frequency reference to the counter circuit 115. The arithmetic circuit 117 calculates a first pressure P1 of the fluid flowing through the first flow path F1 based on the resonance frequency counted by the counter circuit 115.

[0029] The first pressure P1 measured by the first pressure gauge 110 in the above manner is transmitted as information to the upper-level computing unit 130 using the communication function of the first pressure gauge 110.

[0030] Each component included in the second pressure gauge 120 has the same function as the corresponding component included in the first pressure gauge 110. The above-described method for measuring the first pressure P1 of the fluid flowing through the first flow path F1 using the first pressure gauge 110 also applies when the second pressure P2 of the fluid flowing through the third flow path F3 is measured using the second pressure gauge 120.

[0031] However, in the conventional measurement system 100, the first pressure gauge 110 and the second pressure gauge 120 are independent of each other. This reduces the accuracy of flow rate measurement due to individual differences in the characteristics of each pressure gauge. It is difficult to completely match the characteristics of the first pressure gauge 110 and the second pressure gauge 120, and differences in the characteristics inevitably occur. For example, each pressure gauge has its own reference power supply and excitation source. This can reduce the relative accuracy of the output between the sensor elements of the first pressure gauge 110 and the second pressure gauge 120 due to differences in the reference power supply, or can cause significant relative quantization errors due to differences in the excitation sources. This also reduces long-term stability, further reducing the relative accuracy over time.

[0032] Additionally, in the conventional measurement system 100, in order to calculate the pressure difference, it was necessary to place the upper computing unit 130 separately from the first pressure gauge 110 and the second pressure gauge 120. Furthermore, the first pressure gauge 110 and the second pressure gauge 120 had to be placed separately, which increased the space occupied by the entire measurement system 100. For example, it was necessary to provide a reference power supply, a counter circuit, an excitation source, and a computing circuit for each pressure gauge, which increased the space occupied by each pressure gauge.

[0033] An object of the present disclosure is to provide a measurement device that can solve the above problems and improve the accuracy of measuring the flow rate of a fluid flowing through a flow path F.

[0034] Hereinafter, one embodiment of the present disclosure will be mainly described with reference to the accompanying drawings.

[0035] Fig. 1 is a schematic diagram showing an example of the configuration of a measurement device 1 according to an embodiment of the present disclosure. Fig. 2 is a block diagram showing an example of a more detailed configuration of the measurement device 1 of Fig. 1. The configuration of the measurement device 1 according to an embodiment will be mainly described with reference to Figs. 1 and 2.

[0036] The measurement device 1 contributes to measuring the flow rate of a fluid flowing through a flow path F. The measurement device 1 measures the flow rate of the fluid flowing through the flow path F. In this disclosure, "fluid" includes gases, liquids, etc. The flow path F includes a first flow path F1, a second flow path F2, and a third flow path F3. The first flow path F1, the second flow path F2, and the third flow path F3 indicate fluid flow paths. The first flow path F1, the second flow path F2, and the third flow path F3 have different shapes, etc. Therefore, the flow path resistances of these flow paths are different from one another. The second flow path F2 is a flow path with a known flow path resistance, in which the fluid flows at a known flow rate when a pressure difference of the fluid occurs between the left and right ends of the second flow path F2, for example. The fluid flows inside the flow path F, for example, in the order of the first flow path F1, the second flow path F2, and the third flow path F3.

[0037] The measuring device 1 has a plurality of pressure sensor units 10, a single reference power supply 20, a plurality of amplifiers 30, a single counter circuit 40, a single excitation source 50, a single arithmetic circuit 60, and a single communication unit 70. As will be described later, each of the plurality of pressure sensor units 10 has a diaphragm 11 that receives fluid pressure, and a sensor element 12 that outputs an output signal with a frequency corresponding to the pressure received by the diaphragm 11.

[0038] The multiple pressure sensor units 10 are respectively arranged at multiple locations in the flow path F. For example, in the measurement device 1, the multiple pressure sensor units 10 include a first pressure sensor unit 10a and a second pressure sensor unit 10b. The first pressure sensor unit 10a is arranged in the first flow path F1 at a first location L1 adjacent to one end of the second flow path F2. The second pressure sensor unit 10b is arranged in the third flow path F3 at a second location L2 adjacent to the other end of the second flow path F2. The first pressure sensor unit 10a and the second pressure sensor unit 10b are used to measure the pressure difference between the left and right ends of the second flow path F2.

[0039] The first pressure sensor unit 10a includes, in order from the first flow path F1 side, a first diaphragm 11a and a first sensor element 12a. The first sensor element 12a includes a first oscillator 121a, a second oscillator 122a, and a first diode 123a. The first sensor element 12a includes two oscillators that output output signals, namely, the first oscillator 121a and the second oscillator 122a.

[0040] The first diaphragm 11a bends with a predetermined tension when subjected to a first pressure P1 from the fluid flowing through the first flow path F1. The amount of deformation of the first diaphragm 11a depends on the first pressure P1. The first sensor element 12a outputs, as an output signal, a current with a resonant frequency that depends on the amount of deformation of the first diaphragm 11a, i.e., on the first pressure P1. The resonant frequency of the current changes in response to changes in the first pressure P1 from the fluid flowing through the first flow path F1.

[0041] When the first diaphragm 11a is deformed by the first pressure P1 of the fluid flowing through the first flow path F1, the first oscillator 121a of the first sensor element 12a is distorted in accordance with the first deformation amount of the first diaphragm 11a. The first oscillator 121a has a first resonant frequency determined, for example, by the shape of its beam. In addition, a first self-excited circuit is formed that vibrates the first oscillator 121a at the first resonant frequency based on a first bias voltage applied from the reference power supply 20 between the first oscillator 121a and the fixed electrode. As a result, the first oscillator 121a outputs, as an output signal, a first current having a first resonant frequency that depends on the first deformation amount of the first diaphragm 11a, i.e., on the first pressure P1.

[0042] When the first diaphragm 11a is deformed by the first pressure P1 of the fluid flowing through the first flow path F1, the second oscillator 122a of the first sensor element 12a is distorted in accordance with the second deformation amount of the first diaphragm 11a. The second oscillator 122a has a second resonant frequency determined, for example, by the shape of its beam. In addition, a second self-oscillating circuit is formed that vibrates the second oscillator 122a at the second resonant frequency based on a second bias voltage applied from the reference power supply 20 between the second oscillator 122a and the fixed electrode. As a result, the second oscillator 122a outputs a second current having a second resonant frequency as an output signal that depends on the second deformation amount of the first diaphragm 11a, i.e., on the first pressure P1.

[0043] The first diode 123a of the first sensor element 12a outputs a voltage proportional to the ambient temperature. The first diode 123a built in the first sensor element 12a outputs the voltage by passing a constant current through it. The on-voltage of the first diode 123a is used as the temperature output of the first sensor element 12a.

[0044] The second pressure sensor unit 10b includes, in order from the third flow path F3 side, a second diaphragm 11b and a second sensor element 12b. The second sensor element 12b includes a third oscillator 121b, a fourth oscillator 122b, and a second diode 123b.

[0045] The second diaphragm 11b bends with a predetermined tension when subjected to the second pressure P2 of the fluid flowing through the third flow path F3. The amount of deformation of the second diaphragm 11b depends on the second pressure P2. The second sensor element 12b outputs, as an output signal, a current with a resonant frequency that depends on the amount of deformation of the second diaphragm 11b, i.e., on the second pressure P2. The resonant frequency of the current changes in response to changes in the second pressure P2 of the fluid flowing through the third flow path F3.

[0046] When the second diaphragm 11b is deformed by the second pressure P2 of the fluid flowing through the third flow path F3, the third oscillator 121b of the second sensor element 12b is distorted in accordance with the third deformation amount of the second diaphragm 11b. The third oscillator 121b has a third resonant frequency determined, for example, by the shape of its beam. In addition, a third self-oscillating circuit is formed that causes the third oscillator 121b to vibrate at the third resonant frequency based on a third bias voltage applied from the reference power supply 20 between the third oscillator 121b and the fixed electrode. As a result, the third oscillator 121b outputs a third current having a third resonant frequency as an output signal that depends on the third deformation amount of the second diaphragm 11b, i.e., on the second pressure P2.

[0047] When the second diaphragm 11b is deformed by the second pressure P2 of the fluid flowing through the third flow path F3, the fourth oscillator 122b of the second sensor element 12b is distorted in accordance with the fourth deformation amount of the second diaphragm 11b. The fourth oscillator 122b has a fourth resonant frequency determined, for example, by the shape of its beam. In addition, a fourth self-oscillating circuit is formed that vibrates the fourth oscillator 122b at the fourth resonant frequency based on a fourth bias voltage applied from the reference power supply 20 between the fourth oscillator 122b and the fixed electrode. As a result, the fourth oscillator 122b outputs a fourth current having a fourth resonant frequency as an output signal that depends on the fourth deformation amount of the second diaphragm 11b, i.e., on the second pressure P2.

[0048] The second diode 123b of the second sensor element 12b outputs a voltage proportional to the ambient temperature. The second diode 123b built in the second sensor element 12b outputs the voltage by passing a constant current through it. The on-voltage of the second diode 123b is used as the temperature output of the second sensor element 12b.

[0049] The reference power supply 20 applies a bias voltage to the corresponding vibrator to cause the vibrator to output a current having a resonant frequency as an output signal. The reference power supply 20 provides a common voltage reference to each of the multiple pressure sensor units 10. For example, the reference power supply 20 provides a first voltage reference that serves as the basis for the first bias voltage and the second bias voltage applied to the first vibrator 121a and the second vibrator 122a of the first sensor element 12a, respectively. For example, the reference power supply 20 provides a second voltage reference that serves as the basis for the third bias voltage and the fourth bias voltage applied to the third vibrator 121b and the fourth vibrator 122b of the second sensor element 12b, respectively. The first voltage reference and the second voltage reference are common to each other.

[0050] The multiple amplifiers 30 respectively amplify the outputs from the multiple pressure sensor units 10. For example, in the measurement device 1, the multiple amplifiers 30 include a first amplifier 30a that amplifies the output from the first pressure sensor unit 10a and a second amplifier 30b that amplifies the output from the second pressure sensor unit 10b.

[0051] The counter circuit 40 commonly counts the frequency of the output signal output from each of the multiple pressure sensor units 10. The counter circuit 40 counts the frequency of the output signal based on a clock signal output from a common excitation source 50, which has a frequency higher than the frequency of the output signal. The frequency of the output signal is used to calculate the pressure of the fluid at the corresponding location in the flow path F where the pressure sensor unit 10 is located. The pressure of the fluid is related to the flow rate of the fluid.

[0052] For example, the counter circuit 40 counts a first resonant frequency based on the first oscillator 121a, a second resonant frequency based on the second oscillator 122a, a third resonant frequency based on the third oscillator 121b, and a fourth resonant frequency based on the fourth oscillator 122b based on a common clock signal. The counter circuit 40 commonly counts a first frequency for calculating a first pressure P1 of the fluid at a first location L1 where the first pressure sensor unit 10a is disposed, and a second frequency for calculating a second pressure P2 of the fluid at a second location L2 where the second pressure sensor unit 10b is disposed.

[0053] In the present disclosure, the "first frequency" includes, for example, the first resonant frequency and the second resonant frequency. The "second frequency" includes, for example, the third resonant frequency and the fourth resonant frequency. That is, the first resonant frequency and the second resonant frequency obtained based on the first pressure sensor unit 10a are used to calculate a first pressure P1 of the fluid at a first location L1 where the first pressure sensor unit 10a is disposed in the flow path F. The third resonant frequency and the fourth resonant frequency obtained based on the second pressure sensor unit 10b are used to calculate a second pressure P2 of the fluid at a second location L2 where the second pressure sensor unit 10b is disposed in the flow path F.

[0054] The excitation source 50 provides a frequency reference to the counter circuit 40. The excitation source 50 outputs to the counter circuit 40 a clock signal that is commonly used to count the first resonant frequency, the second resonant frequency, the third resonant frequency, and the fourth resonant frequency.

[0055] The arithmetic circuit 60 includes one or more processors. In this disclosure, a "processor" refers to, but is not limited to, a general-purpose processor or a dedicated processor specialized for a specific process. The arithmetic circuit 60 calculates the pressure of the fluid at the corresponding location based on the frequency counted by the counter circuit 40. The arithmetic circuit 60 is a circuit that performs calculations using software to output the frequency as a pressure display value.

[0056] For example, the arithmetic circuit 60 calculates a first pressure P1 of the fluid at a first location L1 where the first pressure sensor unit 10a is disposed, using the first and second resonant frequencies counted by the counter circuit 40 and the on-voltage of the first diode 123a output from the first diode 123a of the first sensor element 12a. For example, the arithmetic circuit 60 calculates a second pressure P2 of the fluid at a second location L2 where the second pressure sensor unit 10b is disposed, using the third and fourth resonant frequencies counted by the counter circuit 40 and the on-voltage of the second diode 123b output from the second diode 123b of the second sensor element 12b.

[0057] The arithmetic circuit 60 calculates the flow rate of the fluid based on the pressure difference of the fluid between a plurality of locations. For example, the arithmetic circuit 60 calculates the flow rate of the fluid flowing through the second flow path F2 based on the difference between the first pressure P1 and the second pressure P2, which are the pressure difference of the fluid between the first location L1 where the first pressure sensor unit 10a is arranged and the second location L2 where the second pressure sensor unit 10b is arranged.

[0058] The communication unit 70 includes a communication interface that conforms to any communication standard based on wireless or wired communication. Communication standards include wireless LAN (Local Area Network) standards, short-range wireless communication standards, mobile communication standards such as 4G (4th Generation) and 5G (5th Generation), and Internet standards. The measurement device 1 is connected to an information and communication network via the communication unit 70. The communication unit 70 transmits the calculation results obtained by the arithmetic circuit 60 as needed to an external device that is communicatively connected to the measurement device 1 via the information and communication network.

[0059] The measurement device 1 has a first pressure sensor unit 10a and a second pressure sensor unit 10b arranged at both ends of a second flow path F2 having a known flow path resistance in order to measure the flow rate of the fluid flowing through the flow path F. The measurement device 1 measures the pressure difference between both ends of the second flow path F2 using the first pressure sensor unit 10a and the second pressure sensor unit 10b. The measurement device 1 measures the flow rate of the fluid flowing through the second flow path F2 based on the measured pressure difference and the known flow path resistance of the second flow path F2.

[0060] More specifically, the arithmetic circuit 60 of the measurement device 1 calculates the pressures obtained by the two pressure sensor units 10, which are respectively arranged at both ends of the second flow path F2, and the pressure difference therebetween, to calculate the flow rate of the fluid. The arithmetic circuit 60 calculates the pressure P obtained by each pressure sensor unit 10 based on the following equations (1) to (7). The pressure P corresponds to the above-mentioned first pressure P1 or second pressure P2.

[0061]

number

[0062] As described above, two oscillators are arranged in the sensor element 12 of each pressure sensor unit 10. The subscript "C" in equations (1) to (7) indicates that the parameter is related to one of the two oscillators. The subscript "R" in equations (1) to (7) indicates that the parameter is related to the other of the two oscillators.

[0063] The parameters included in the formulas (1) to (7) are explained in the following Table 1. Note that the subscript "X" in Table 1 corresponds to the above "C" or "R." [Table 1]

[0064] In this disclosure, the "reference state" refers to, for example, a state in which a reference fluid pressure is applied to the diaphragm 11. The "effective gap length" refers to, for example, the distance between the vibrating beam of the corresponding vibrator and the surface of the fixed electrode facing the vibrating beam. The "tension generated in the vibrator in the reference state" refers to, for example, the tensile strain of the vibrating beam.

[0065] For example, if pressure P corresponds to a first pressure P1, then f C corresponds to the first resonant frequency. f R corresponds to the second resonant frequency. 0C corresponds to the first resonant frequency in the reference state. 0R corresponds to the second resonant frequency in the reference state. C , L C , d C , ε C , Δε C corresponds to a parameter related to the first oscillator 121a. R , L R , d R , ε R , Δε R corresponds to a parameter related to the second oscillator 122a. CB corresponds to the first bias voltage. V RB corresponds to the second bias voltage. TS corresponds to the on-voltage of the first diode 123a. 0TS corresponds to the on-voltage of the first diode 123a in the reference state. T corresponds to the ambient temperature of the first sensor element 12a.

[0066] For example, if the pressure P corresponds to a second pressure P2, then f C corresponds to the third resonance frequency. R corresponds to the fourth resonant frequency. 0C corresponds to the third resonance frequency in the reference state. 0R corresponds to the fourth resonance frequency in the reference state. C , L C , d C , ε C , Δε C corresponds to a parameter related to the third oscillator 121b.R , L R , d R , ε R , Δε R corresponds to a parameter related to the fourth oscillator 122b. CB corresponds to the third bias voltage. V RB corresponds to the fourth bias voltage. TS corresponds to the on-voltage of the second diode 123b. 0TS corresponds to the on-voltage of the second diode 123b in the reference state. T corresponds to the ambient temperature of the second sensor element 12b.

[0067] In equation (1), "i" and "j" are used to correct the orders of the parameters X and T in the pressure P, respectively. For example, when the vertical axis is set to pressure and the horizontal axis is set to resonance frequency, the graph based on equation (1) does not necessarily change linearly. In order to calculate the pressure P with high accuracy, it is necessary to correct X and T for calculating the pressure P by a predetermined order. Therefore, "n" and "m" are appropriately determined by the user or the like for such correction. ij are the coefficients corresponding to each order.

[0068] The measuring device 1 according to the embodiment described above can improve the accuracy of measuring the flow rate of a fluid flowing through a flow path F. The measuring device 1 has a single reference power supply 20, a single counter circuit 40, and a single excitation source 50, which can be commonly arranged for a plurality of pressure sensor units 10. Therefore, the measuring device 1 enables synchronized simultaneous measurements for each pressure sensor unit 10.

[0069] Additionally, the measurement device 1 can reduce individual differences in the characteristics of each pressure sensor unit 10 and improve the accuracy of flow rate measurement. For example, by providing a common reference power supply 20 for each pressure sensor unit 10, the relative accuracy of the outputs between the sensor elements 12 based on the reference power supply 20 is improved. For example, by providing a common excitation source 50 for each pressure sensor unit 10, the relative quantization error caused by the excitation source 50 is reduced. Furthermore, the long-term stability caused by the reference power supply 20 and the excitation source 50 is improved, and the deterioration of the relative accuracy over time is suppressed.

[0070] The measuring device 1 can also contribute to reducing the substrate area by sharing the electric circuit portion among the multiple pressure sensor units 10. Therefore, it becomes easy to reduce the size of the measuring system including the measuring device 1.

[0071] The measurement device 1 further includes a single arithmetic circuit 60, which makes it possible to arrange multiple pressure sensor units 10 and the arithmetic circuit 60 within the same device. This allows the measurement device 1 to perform synchronized simultaneous measurements for each pressure sensor unit 10, while reducing the space occupied by a measurement system including the measurement device 1 and contributing to its miniaturization.

[0072] The measurement device 1 can measure the flow rate of the fluid flowing through the flow path F with high accuracy by the calculation circuit 60 calculating the flow rate based on the pressure difference of the fluid.

[0073] The measuring device 1 further includes a communication unit 70 that transmits the calculation results of the arithmetic circuit 60 to an external device, and is thereby able to provide the calculation results of the arithmetic circuit 60 to the external device as information as needed. This allows the measuring device 1 to display the calculation results as information on the external device and prompt the user to confirm the information. The measuring device 1 also allows the external device to display measurement parameters such as the pressures P, pressure difference, and flow rate calculated by the arithmetic circuit 60 and prompt the user to confirm the measurement parameters.

[0074] In the measuring device 1, each of the multiple pressure sensor units 10 has a diaphragm 11 and a sensor element 12, and therefore an output signal having a frequency corresponding to the pressure P received by the diaphragm 11 can be output from each of the multiple pressure sensor units 10. This allows the measuring device 1 to calculate the flow rate of the fluid based on the pressure difference of the fluid between multiple points in the flow path F.

[0075] Since the sensor element 12 of the measuring device 1 has two vibrators and one diode, the calculation circuit 60 receives information on two resonant frequencies and one diode on-voltage, and the measuring device 1 can calculate the pressure P for each pressure sensor unit 10 based on the above-mentioned equations (1) to (3).

[0076] The multiple pressure sensor units 10 include a first pressure sensor unit 10a and a second pressure sensor unit 10b. The counter circuit 40 commonly counts a first frequency for calculating the first pressure P1 and a second frequency for calculating the second pressure P2. This allows the measurement device 1 to have two pressure sensor units 10 within a single device and to simultaneously measure two pressures P.

[0077] It will be apparent to those skilled in the art that the present disclosure may be embodied in other specific forms other than the above-described embodiments without departing from the spirit or essential characteristics thereof. Therefore, the foregoing description is illustrative and not limiting. The scope of the disclosure is defined not by the foregoing description but by the appended claims. All modifications within the range of equivalents of any modifications are intended to be embraced therein.

[0078] For example, the shape, size, arrangement, orientation, and number of each of the above-mentioned components are not limited to those shown in the above description and drawings. The shape, size, arrangement, orientation, and number of each component may be configured arbitrarily as long as the function can be realized. The components of the illustrated measuring device 1 are functional concepts, and the specific form of each component is not limited to those shown.

[0079] In the above embodiment, the measurement device 1 is described as further including a single arithmetic circuit 60 that calculates the pressure of the fluid at a corresponding location based on the frequency counted by the counter circuit 40. However, this is not limited to this. The measurement device 1 does not necessarily have to include the arithmetic circuit 60.

[0080] In the above embodiment, the arithmetic circuit 60 is described as calculating the flow rate based on the pressure difference of the fluid between multiple locations, but this is not limited to this. The arithmetic circuit 60 does not have to calculate the flow rate. In this case, the measurement device 1 may output only the pressures P and the pressure difference of the fluid as information to an external device. The arithmetic circuit 60 may calculate the flow rate based on a method other than the calculation method based on the pressure difference of the fluid between multiple locations.

[0081] In the above embodiment, the measurement device 1 is described as further including a communication unit 70 that transmits the calculation results of the arithmetic circuit 60 to an external device, but this is not limiting. The measurement device 1 does not necessarily have to include the communication unit 70. The measurement device 1 may include the arithmetic circuit 60 but not the communication unit 70, or may not include the arithmetic circuit 60 and the communication unit 70.

[0082] In the above embodiment, each of the multiple pressure sensor units 10 has been described as having a diaphragm 11 that receives fluid pressure and a sensor element 12 that outputs an output signal with a frequency that corresponds to the pressure received by the diaphragm 11, but this is not limited to this. The configuration of the pressure sensor unit 10 is not limited to a combination of the diaphragm 11 and the sensor element 12, and may be any other configuration that can measure the pressure P of the fluid.

[0083] In the above embodiment, the sensor element 12 has been described as having two vibrators that output an output signal and one diode that outputs a voltage proportional to the ambient temperature, but is not limited to this. The sensor element 12 may have any other configuration that can output a signal required for the calculation circuit 60 to calculate the pressure P or flow rate of the fluid.

[0084] 3 is a schematic diagram showing an example of the configuration of a measurement device 1 according to a modified example of the present disclosure. In the above embodiment, the multiple pressure sensor units 10 have been described as including a first pressure sensor unit 10a and a second pressure sensor unit 10b, but this is not limited to this. The multiple pressure sensor units 10 may include three or more pressure sensor units 10 instead of two. For example, the multiple pressure sensor units 10 may further include a third pressure sensor unit 10c for measuring a third pressure P3 of the fluid at a third location L3, in addition to the first pressure sensor unit 10a and the second pressure sensor unit 10b.

[0085] Accordingly, the plurality of diaphragms 11 may further include a third diaphragm 11c in addition to the first diaphragm 11a and the second diaphragm 11b. The plurality of sensor elements 12 may further include a third sensor element 12c in addition to the first sensor element 12a and the second sensor element 12b. The plurality of amplifiers 30 may further include a third amplifier 30c in addition to the first amplifier 30a and the second amplifier 30b.

[0086] In this case, the single counter circuit 40 may commonly count a first frequency for calculating a first pressure P1 of the fluid at a first location L1 where the first pressure sensor unit 10a is located, a second frequency for calculating a second pressure P2 of the fluid at a second location L2 where the second pressure sensor unit 10b is located, and a third frequency for calculating a third pressure P3 of the fluid at a third location L3 where the third pressure sensor unit 10c is located.

[0087] As described above, the measurement device 1 can also be applied to a multi-input system based on multiple pressure sensor units 10. The measurement device 1 can simultaneously measure the first pressure P1, second pressure P2, and third pressure P3 generated in the first flow path F1, second flow path F2, and third flow path F3, respectively. The configuration of the measurement device 1 is not limited to two or three inputs, and can be changed depending on the pressure P to be measured so as to have four or more inputs.

[0088] Even in the above case, the measurement device 1 has a single reference power supply 20, a single counter circuit 40, and a single excitation source 50 for the multiple pressure sensor units 10. In the measurement device 1, the reference power supply 20 and the excitation source 50 each contribute to the relative accuracy and relative quantization error of the outputs between the sensor elements 12. By sharing the reference power supply 20 and the excitation source 50, which primarily affect the relative accuracy, for the multiple pressure sensor units 10, the measurement device 1 can achieve measurements with higher accuracy over the long term compared to a case in which single-input pressure sensor units 10 are individually arranged in multiple flow paths F. The measurement device 1 exhibits similar effects not only in a two-input device configuration as in the above embodiment, but also in a device configuration with three or more inputs.

[0089] In the above embodiment, the output signal from the sensor element 12 is based on a current, but is not limited to this. The output signal from the sensor element 12 may be based on a voltage.

[0090] The measurement device 1 according to an embodiment of the present disclosure can be used, for example, in a system configuration of a pressure sensor that performs two-input simultaneous measurement for the purpose of improving simultaneous measurement capability, measurement accuracy, and long-term stability. For example, the measurement device 1 can be used as a compact, high-precision flow rate measurement device that can be built into an apparatus.

[0091] Some embodiments of the present disclosure will be described below as examples, however, it should be noted that the embodiments of the present disclosure are not limited to these examples. [Appendix 1] A measuring device that contributes to measuring the flow rate of a fluid flowing through a flow path, comprising: a plurality of pressure sensor units respectively disposed at a plurality of locations in the flow path; a single reference power supply that provides a common voltage reference for each of the plurality of pressure sensor units; a single counter circuit that commonly counts the frequency of an output signal output from each of the plurality of pressure sensor units, the frequency being used to calculate the pressure of the fluid at the corresponding location, which is associated with the flow rate; a single excitation source providing a frequency reference for said counter circuit; Equipped with Measuring equipment. [Appendix 2] 10. The measurement device of claim 1, a single calculation circuit for calculating the pressure of the fluid at the corresponding location based on the frequency counted by the counter circuit; Measuring equipment. [Appendix 3] 10. The measurement device of claim 2, the calculation circuit calculates the flow rate based on a pressure difference of the fluid among the plurality of locations. Measuring equipment. [Appendix 4] 4. The measurement device according to claim 2 or 3, a communication unit that transmits the calculation result of the calculation circuit to an external device; Measuring equipment. [Appendix 5] 5. The measurement device according to claim 1, further comprising: Each of the plurality of pressure sensor units includes a diaphragm that receives the pressure of the fluid, and a sensor element that outputs the output signal at the frequency corresponding to the pressure received by the diaphragm. Measuring equipment. [Appendix 6] 6. The measurement device of claim 5, The sensor element has two vibrators that output the output signal and one diode that outputs a voltage proportional to the ambient temperature. Measuring equipment. [Appendix 7] 7. The measurement device according to any one of claims 1 to 6, the plurality of pressure sensor units include a first pressure sensor unit and a second pressure sensor unit, the single counter circuit commonly counts a first frequency for calculating a first pressure of the fluid at a first location where the first pressure sensor unit is disposed, and a second frequency for calculating a second pressure of the fluid at a second location where the second pressure sensor unit is disposed. Measuring equipment. [Explanation of symbols]

[0092] 1. Measuring equipment 10 Pressure sensor section 10a First pressure sensor section 10b Second pressure sensor section 10c Third pressure sensor section 11 Diaphragm 11a First diaphragm 11b Second diaphragm 11c Third diaphragm 12 Sensor element 12a First sensor element 121a First oscillator 122a 2nd oscillator 123a First diode 12b Second sensor element 121b Third oscillator 122b 4th oscillator 123b Second diode 12c Third sensor element 20 Reference power supply 30 amps 30a 1st amplifier 30b Second amplifier 30c 3rd amplifier 40 Counter Circuit 50 Excitation source 60 Arithmetic circuit 70 Communications Department F flow path F1 First flow path F2 Second flow path F3 Third flow path L1 1st place L2 2nd place L3 Third Place P1 First pressure P2 Second pressure P3 Third pressure 100 Measurement System 110 First pressure gauge 111 diaphragm 112 Sensor element 113 Reference power supply 114 Amplifier 115 Counter Circuit 116 Excitation source 117 Arithmetic circuit 120 Second pressure gauge 121 diaphragm 122 Sensor element 123 Reference power supply 124 Amplifier 125 Counter Circuit 126 Excitation source 127 Arithmetic circuit 130 Arithmetic unit

Claims

1. A measuring device that contributes to measuring the flow rate of a fluid flowing through a flow path, comprising: a plurality of pressure sensor units respectively disposed at a plurality of locations in the flow path; a single reference power supply that provides a common voltage reference for each of the plurality of pressure sensor units; a single counter circuit that commonly counts the frequency of an output signal output from each of the plurality of pressure sensor units, the frequency being used to calculate the pressure of the fluid at the corresponding location, which is associated with the flow rate; a single excitation source providing a frequency reference for said counter circuit; Equipped with performing synchronized simultaneous measurements for each of the pressure sensor units; Measuring equipment.

2. 2. The measuring device according to claim 1, a single calculation circuit that calculates the pressure of the fluid at the corresponding location based on the frequency counted by the counter circuit; Measuring equipment.

3. 3. The measuring device according to claim 2, the calculation circuit calculates the flow rate based on a pressure difference of the fluid among the plurality of locations. Measuring equipment.

4. The measuring device according to claim 2 or 3, a communication unit that transmits the calculation result of the calculation circuit to an external device; Measuring equipment.

5. 4. The measuring device according to claim 1, Each of the plurality of pressure sensor units includes a diaphragm that receives the pressure of the fluid, and a sensor element that outputs the output signal at the frequency corresponding to the pressure received by the diaphragm. Measuring equipment.

6. 6. The measuring device according to claim 5, The sensor element has two vibrators that output the output signal and one diode that outputs a voltage proportional to the ambient temperature. Measuring equipment.

7. 4. The measuring device according to claim 1, the plurality of pressure sensor units include a first pressure sensor unit and a second pressure sensor unit, the single counter circuit commonly counts a first frequency for calculating a first pressure of the fluid at a first location where the first pressure sensor unit is disposed, and a second frequency for calculating a second pressure of the fluid at a second location where the second pressure sensor unit is disposed. Measuring equipment.

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