Clamp-on ultrasonic flow sensor

Abstract

To provide a clamp-on ultrasonic flow-rate sensor capable of easily determining the abnormality of flow-rate measurement state including the attachment state of an ultrasonic element to a piping.SOLUTION: Two ultrasonic elements are attached to an outer circumferential surface of a pipe. In a measurement mode for measuring a flow-rate of a fluid in the pipe, a flow-rate calculation unit 310 calculates the flow-rate of the fluid in the pipe by controlling the two ultrasonic elements. In a diagnosis mode for diagnosing a state regarding measurement of fluid flow-rate, a measurement determination unit 320 controls one of the ultrasonic elements so as to causes an ultrasonic wave to be transmitted from the ultrasonic element to the fluid inside the pipe. The measurement determination unit 320 also determines the state of flow-rate measurement of the fluid on the basis of a signal outputted from an ultrasonic element that is to receive the ultrasonic wave transmitted from the one of the two ultrasonic elements.SELECTED DRAWING: Figure 23

Description

Technical Field

[0001] The present invention relates to a clamp-on ultrasonic flow sensor for measuring the flow rate of a fluid flowing through a pipe.

Background Art

[0002] An ultrasonic flow sensor that measures the flow rate of a fluid flowing through a pipe by being attached to the pipe is known. For example, in the ultrasonic flow switch described in Patent Document 1, an upper clamp member and a lower clamp member are arranged so as to sandwich the pipe and are coupled using screws. Further, a housing portion that houses two ultrasonic elements is detachably fixed to the upper clamp member. In this state, ultrasonic waves are transmitted from one ultrasonic element through the fluid in the pipe to the other ultrasonic element, and ultrasonic waves are transmitted from the other ultrasonic element through the fluid in the pipe to the one ultrasonic element.

[0003] The time difference between the time when ultrasonic waves are transmitted by one ultrasonic element and the time when the ultrasonic waves are received by the other ultrasonic element, and the time difference between the time when ultrasonic waves are transmitted by the other ultrasonic element and the time when the ultrasonic waves are received by the one ultrasonic element are calculated. Based on the calculated time difference and a predetermined mathematical formula, the flow rate of the fluid flowing through the pipe is calculated.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the ultrasonic flow switch described above, an acoustic couplant is provided between each ultrasonic element and the pipe to reduce the attenuation of ultrasound reaching the fluid in the pipe from each ultrasonic element, and the attenuation of ultrasound reaching each ultrasonic element from the fluid in the pipe. If there is a gap between the acoustic couplant and the outer surface of the pipe, it is not possible to reduce the attenuation of ultrasound generated between each ultrasonic element and the fluid in the pipe. As a result, the accuracy of flow measurement decreases. In this case, the user needs to adjust the contact condition of the acoustic couplant with the pipe.

[0006] A decrease in flow rate measurement accuracy can occur due to factors other than the contact condition of the acoustic couplant with the piping. For example, prolonged use of each ultrasonic element can cause the characteristics of each ultrasonic element to deteriorate, resulting in a decrease in flow rate measurement accuracy. Therefore, when the flow rate measurement accuracy of the ultrasonic flow switch described above decreases, it is difficult for the user to determine the cause.

[0007] Patent Document 2 proposes an ultrasonic flow meter for measuring the flow rate of fluid flowing through a pipe, which diagnoses the deterioration of two ultrasonic transducers used to calculate the flow rate. However, the ultrasonic flow meter described in Patent Document 2 is a so-called in-line type ultrasonic flow sensor in which the two ultrasonic transducers are arranged within the flow path of the pipe. Therefore, in ultrasonic flow sensors of the type in which ultrasonic elements are attached to the outer surface of the pipe, it is not intended to determine whether the mounting condition of the ultrasonic elements is good or bad.

[0008] The object of the present invention is to provide a clamp-on ultrasonic flow sensor that enables users to easily identify abnormalities in the flow measurement state, including the mounting state of the ultrasonic element to the piping. [Means for solving the problem]

[0009] (1) The clamp-on ultrasonic flow sensor according to the first invention is a clamp-on ultrasonic flow sensor for measuring the flow rate of fluid flowing in a pipe, comprising: a first ultrasonic element attached to a part of the outer surface of the pipe, capable of transmitting and receiving ultrasonic waves toward the pipe, and outputting a signal indicating the intensity of the received ultrasonic waves when ultrasonic waves are received; a second ultrasonic element attached to another part of the outer surface of the pipe, capable of transmitting and receiving ultrasonic waves toward the pipe, and outputting a signal indicating the intensity of the received ultrasonic waves when ultrasonic waves are received; and a control unit configured to operate in a measurement mode for measuring the flow rate of the fluid and a diagnostic mode for diagnosing the state related to the measurement of the flow rate of the fluid. The control unit includes a flow rate calculation unit that calculates the fluid flow rate by controlling the first and second ultrasonic elements in measurement mode, and a measurement determination unit that, in diagnostic mode, controls the first ultrasonic element to cause it to transmit ultrasonic waves and determines the measured state of the fluid flow rate in a sequence different from that of the measurement mode, based on signals output from the ultrasonic element that should receive the ultrasonic waves transmitted from the first ultrasonic element. The measurement determination unit makes at least one of the following determinations regarding the measured state of the fluid flow rate: whether the first ultrasonic element is abnormal, and whether the mounting state of the first ultrasonic element is abnormal. The fluid flow rate measurement state includes multiple measurement states corresponding to multiple diagnostic items, and the clamp-on ultrasonic flow sensor displays multiple diagnostic items side by side, and further includes a display unit that displays the judgment result of each measurement state determined by the measurement judgment unit in correspondence with the diagnostic item of that measurement state. .

[0010] In this clamp-on ultrasonic flow sensor, when the control unit is in measurement mode, the flow rate of the fluid flowing through the pipe is measured by controlling the first and second ultrasonic elements. On the other hand, when the control unit is in diagnostic mode, ultrasonic waves are transmitted from the first ultrasonic element towards the pipe.

[0011] If there is an abnormality in the mounting of the first ultrasonic element to the pipe, the ultrasonic waves transmitted from the first ultrasonic element toward the pipe will either not be transmitted to the pipe or will be greatly attenuated at the surface of the pipe. Similarly, ultrasonic waves that should be transmitted from inside the pipe to the first ultrasonic element will either not be transmitted to the first ultrasonic element or will be greatly attenuated at the surface of the pipe. The same applies to the second ultrasonic element; if there is an abnormality in the mounting of the second ultrasonic element to the pipe, the ultrasonic waves transmitted from the second ultrasonic element toward the pipe will either not be transmitted to the pipe or will be greatly attenuated at the surface of the pipe. Similarly, ultrasonic waves that should be transmitted from inside the pipe to the second ultrasonic element will either not be transmitted to the second ultrasonic element or will be greatly attenuated at the surface of the pipe.

[0012] Therefore, the output signal of the ultrasonic element that should receive the transmitted ultrasonic waves makes it easy to determine at least the mounting status of the first ultrasonic element to the piping. Consequently, users can easily identify any abnormalities in the flow rate measurement status, including the mounting status of the ultrasonic element to the piping. According to the above configuration, in order to determine the measurement state of the fluid flow rate, at least one of the following is determined: whether the first ultrasonic element is abnormal or whether the mounting state of the first ultrasonic element is abnormal or not. Furthermore, the display unit described above allows users to easily understand the measurement status of the fluid flow rate through the piping.

[0013] (2 ) system While in diagnostic mode, the system may perform determinations of multiple measurement states according to a predetermined sequence of diagnostic items. This ensures that the order of the diagnostic items is appropriately determined, thereby enabling appropriate determination of multiple measurement states.

[0014] (3) The multiple diagnostic items include a first diagnostic item for determining whether the first ultrasonic element is abnormal, a second diagnostic item for determining whether the mounting state of the first ultrasonic element is abnormal, a third diagnostic item for determining whether the inside of the pipe is filled with fluid, and a fourth diagnostic item for determining whether there are more than a predetermined amount of bubbles in the fluid inside the pipe. The control unit may, while in diagnostic mode, perform a determination of the measurement state corresponding to the first and second diagnostic items as part of the diagnostic mode sequence, and then perform a determination of the measurement state corresponding to the third and fourth diagnostic items.

[0015] The measurement status corresponding to the first and second diagnostic items can be determined, for example, based on the ultrasonic waveform corresponding to the path of the ultrasonic waves transmitted from the first ultrasonic element to the surface of the pipe.

[0016] On the other hand, the measurement status corresponding to the third and fourth diagnostic items can be determined, for example, based on the ultrasonic waveform corresponding to the path of the ultrasonic waves transmitted from the first ultrasonic element from the surface of the pipe to the inside of the pipe.

[0017] Therefore, if the ultrasonic waveform corresponding to the path of the ultrasonic waves transmitted from the first ultrasonic element to the surface of the pipe is not normal, it is not possible to accurately determine the measurement status corresponding to the third and fourth diagnostic items. With the above configuration, the measurement status corresponding to the third and fourth diagnostic items is determined after the measurement status corresponding to the first and second diagnostic items has been determined, thus improving the accuracy of determining the measurement status corresponding to the third and fourth diagnostic items.

[0018] (4) The clamp-on ultrasonic flow sensor may further include a mode switching unit that receives input for the operating mode to which the control unit should switch, and switches the operating mode of the control unit to the received operating mode. In this case, the user can determine an abnormality in the measurement state of the clamp-on ultrasonic flow sensor at a desired timing.

[0019] (5) The flow rate calculation unit may include a first calculation unit that calculates the flow rate of the fluid based on the propagation time difference of ultrasonic waves between the first ultrasonic element and the second ultrasonic element. Thereby, for a fluid with a low content rate of bubbles or particles, etc., the flow rate can be calculated with high accuracy.

[0020] (6) The flow rate calculation unit may include a second calculation unit that calculates the flow rate of the fluid based on the frequency shift of the ultrasonic wave received by the first ultrasonic element when the first ultrasonic element transmits the ultrasonic wave. Thereby, for a fluid with a relatively high content rate of bubbles or particles, etc., the flow rate can be calculated with high accuracy.

[0021] (7) The ultrasonic element to receive the ultrasonic wave transmitted from the first ultrasonic element includes the first ultrasonic element, and a transmission member for transmitting ultrasonic waves is provided between the first ultrasonic element and the pipe. The measurement determination unit is in the first range of the time axis corresponding to the first part in the transmission member of the ultrasonic wave path in the ultrasonic wave waveform indicating the change in the intensity of the ultrasonic wave indicated by the signal output from the first ultrasonic element, and determines whether the first ultrasonic element is abnormal as the measurement state based on whether the intensity of the ultrasonic wave satisfies a predetermined first condition. It may include an element determination unit.

[0022] In this case, the user can easily determine whether the first ultrasonic element is abnormal as the measurement state in the clamp-on ultrasonic flow sensor.

[0023] (8) The ultrasonic element to receive the ultrasonic wave transmitted from the first ultrasonic element includes the first ultrasonic element, and the measurement determination unit is in the second range of the time axis corresponding to the second part including the outer peripheral surface of the pipe in the ultrasonic wave path in the ultrasonic wave waveform indicating the change in the intensity of the ultrasonic wave indicated by the signal output from the first ultrasonic element, and determines whether the mounting state of the first ultrasonic element is abnormal as the measurement state based on whether the intensity of the ultrasonic wave satisfies a predetermined second condition. It may include a mounting determination unit.

[0024] In this case, the user can easily determine whether or not the mounting state of the first ultrasonic element is abnormal as a measurement state in the clamp-on ultrasonic flow sensor.

[0025] (9) The ultrasonic element to receive the ultrasonic wave transmitted from the first ultrasonic element includes the first ultrasonic element, and the measurement determination unit is in a third range of the time axis corresponding to a third portion including the inner peripheral surface of the pipe among the ultrasonic paths in the ultrasonic waveform indicating the change in the intensity of the ultrasonic wave indicated by the signal output from the first ultrasonic element. It may include a filling determination unit that determines whether or not the inside of the pipe is filled with fluid as a measurement state based on whether or not the intensity of the ultrasonic wave satisfies a predetermined third condition.

[0026] In this case, the user can easily determine whether or not the inside of the pipe is filled with fluid as a measurement state in the clamp-on ultrasonic flow sensor.

[0027] (10) The ultrasonic element to receive the ultrasonic wave transmitted from the first ultrasonic element includes the first ultrasonic element, and the measurement determination unit is in a fourth range of the time axis corresponding to a fourth portion inside the pipe among the ultrasonic paths in the ultrasonic waveform indicating the change in the intensity of the ultrasonic wave indicated by the signal output from the first ultrasonic element. It may include a bubble determination unit that determines whether or not there are bubbles in the fluid inside the pipe equal to or more than a predetermined amount as a measurement state based on whether or not the intensity of the ultrasonic wave satisfies a predetermined fourth condition.

[0028] In this case, the user can easily determine whether or not there are bubbles in the fluid inside the pipe equal to or more than a predetermined amount as a measurement state in the clamp-on ultrasonic flow sensor.

[0029] (11) The ultrasonic element to receive the ultrasonic wave transmitted from the first ultrasonic element includes the second ultrasonic element, and the measurement determination unit may include a transmission / reception determination unit that determines the ultrasonic wave transmission state between the first ultrasonic element and the second ultrasonic element as a measurement state based on the signal output from the second ultrasonic element.

[0030] In this case, the user can easily determine whether the ultrasonic transmission state between the first ultrasonic element and the second ultrasonic element is normal as a measurement state in the clamp-on type ultrasonic flow sensor.

[0031] (12) The clamp-on ultrasonic flow sensor according to the second invention is a clamp-on ultrasonic flow sensor for measuring the flow rate of a fluid flowing in a pipe, comprising: an ultrasonic element attached to a part of the outer surface of the pipe, capable of transmitting and receiving ultrasonic waves toward the pipe, and outputting a signal indicating the intensity of the received ultrasonic waves when ultrasonic waves are received; and a control unit configured to operate in a measurement mode for measuring the flow rate of a fluid and a diagnostic mode for diagnosing the state related to the measurement of the flow rate of a fluid, wherein the control unit includes a flow rate calculation unit that calculates the flow rate of a fluid by controlling the ultrasonic element in the measurement mode, and a measurement determination unit that causes the ultrasonic element to transmit ultrasonic waves by controlling the ultrasonic element in the diagnostic mode and determines the measurement state of the flow rate of a fluid based on the signal output from the ultrasonic element, wherein the measurement determination unit determines at least one of the following: whether the ultrasonic element is abnormal or not, and whether the mounting state of the ultrasonic element is abnormal or not, and the measurement state of the flow rate of a fluid includes a plurality of measurement states corresponding to a plurality of diagnostic items, and the clamp-on ultrasonic flow sensor further comprises a display unit that displays the plurality of diagnostic items side by side and displays the determination result of each measurement state determined by the measurement determination unit in correspondence with the diagnostic item of the measurement state. In this clamp-on ultrasonic flow sensor, when the control unit is in measurement mode, the ultrasonic element is controlled to measure the flow rate of the fluid flowing through the pipe. On the other hand, when the control unit is in diagnostic mode, ultrasonic waves are transmitted from the ultrasonic element towards the pipe. If there is an abnormality in the mounting of the ultrasonic element to the piping, the ultrasonic waves transmitted from the ultrasonic element to the piping will either not be transmitted to the piping or will be significantly attenuated at the surface of the piping. Similarly, ultrasonic waves that should be transmitted from inside the piping to the ultrasonic element will either not be transmitted to the ultrasonic element or will be significantly attenuated at the surface of the piping. Therefore, the output signal of the ultrasonic element that should receive the transmitted ultrasound can be used to easily determine at least the mounting status of the ultrasonic element to the piping. Consequently, users can easily identify any abnormalities in the flow rate measurement status, including the mounting status of the ultrasonic element to the piping. According to the above configuration, the measurement status of the fluid flow rate is determined by making at least one of the following determinations: whether the ultrasonic element is abnormal, and whether the mounting condition of the ultrasonic element is abnormal. Furthermore, the display unit described above allows users to easily understand the measurement status of the fluid flow rate through the piping.

[0032] (13) The control unit, while in diagnostic mode, performs a determination of at least one of several measurement states in a predetermined sequence of diagnostic items as the diagnostic mode sequence. The display unit, during the operation of the control unit based on the sequence, displays the determination result by the measurement determination unit for each measurement state for which a determination has been performed, so as to identify the diagnostic item corresponding to that measurement state. For each measurement state for which a determination has not been performed, the display unit indicates that a determination was not made by the measurement determination unit, so as to identify the diagnostic item corresponding to that measurement state. This may be displayed. This allows the user to easily understand the measurement status of the fluid flow rate through the piping, categorized by the type of measurement status. [Effects of the Invention]

[0037] According to the present invention, users can easily identify abnormalities in the flow rate measurement state, including the mounting state of the ultrasonic element to the piping. [Brief explanation of the drawing]

[0038] [Figure 1] This is a side view of an ultrasonic flow sensor according to one embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view showing the configuration of the sensor head in Figure 1. [Figure 3] This diagram illustrates the operation of the sensor head using the propagation time difference method. [Figure 4] This diagram illustrates the operation of the sensor head in the pulsed Doppler method. [Figure 5] This diagram illustrates the operation of the sensor head in a more specific way using the pulsed Doppler method. [Figure 6] This figure shows the relationship between the ultrasonic signal intensity detected over time and the Doppler frequency. [Figure 7]This figure shows the fluid flow rate calculated using the propagation time difference method and the pulsed Doppler method. [Figure 8] This diagram illustrates possible causes of abnormalities in the flow rate measurement status by an ultrasonic flow sensor. [Figure 9] This diagram illustrates possible causes of abnormalities in the flow rate measurement status by an ultrasonic flow sensor. [Figure 10] This diagram illustrates possible causes of abnormalities in the flow rate measurement status by an ultrasonic flow sensor. [Figure 11] This diagram illustrates possible causes of abnormalities in the flow rate measurement status by an ultrasonic flow sensor. [Figure 12] This diagram illustrates possible causes of abnormalities in the flow rate measurement status by an ultrasonic flow sensor. [Figure 13] This figure shows an example of the screen transitions displayed on the display unit in Figure 1 when using the anomaly diagnosis function. [Figure 14] This figure shows an example of the screen transitions displayed on the display unit in Figure 1 when using the anomaly diagnosis function. [Figure 15] This figure shows an example of the screen transitions displayed on the display unit in Figure 1 when using the anomaly diagnosis function. [Figure 16] This figure shows an example of the screen transitions displayed on the display unit in Figure 1 when using the anomaly diagnosis function. [Figure 17] This figure shows an example of the screen transitions displayed on the display unit in Figure 1 when using the anomaly diagnosis function. [Figure 18] This figure shows an example of the screen transitions displayed on the display unit in Figure 1 when using the anomaly diagnosis function. [Figure 19] This figure shows an example of the screen transitions displayed on the display unit in Figure 1 when using the anomaly diagnosis function. [Figure 20] This figure shows an example of the screen transitions displayed on the display unit in Figure 1 when using the anomaly diagnosis function. [Figure 21] This figure shows an example of the screen transitions displayed on the display unit in Figure 1 when using the anomaly diagnosis function. [Figure 22]This figure shows an example of the screen transitions displayed on the display unit in Figure 1 when using the anomaly diagnosis function. [Figure 23] This is a block diagram illustrating the functional configuration of the control unit in the control board shown in Figure 3. [Figure 24] This flowchart shows the flow of the anomaly diagnosis process to implement the anomaly diagnosis function. [Figure 25] This flowchart shows the flow of the anomaly diagnosis process to implement the anomaly diagnosis function. [Modes for carrying out the invention]

[0039] Hereinafter, a clamp-on type ultrasonic flow sensor according to one embodiment of the present invention will be described with reference to the drawings. In the following description, the clamp-on type ultrasonic flow sensor will be abbreviated as ultrasonic flow sensor.

[0040] [1] Schematic configuration of an ultrasonic flow sensor Figure 1 is a side view of an ultrasonic flow sensor according to one embodiment of the present invention. As shown in Figure 1, the ultrasonic flow sensor 100 consists of a sensor head 10, a clamp part 20, and a display unit 30. The sensor head 10 is attached to a pipe P and calculates the flow rate of the fluid flowing through the pipe P. The maximum inner diameter (diameter) of the pipe P is, for example, the inner diameter corresponding to the nominal pipe diameter "50A" specified in the JIS standard. For example, the inner diameter of a steel pipe with a nominal pipe diameter of "50A" is 52.9 mm. In the following description, an example in which the sensor head 10 is attached to the upper surface of a horizontally extending pipe P will be described.

[0041] The sensor head 10 includes a connector 12. The connector 12 is located on the upper surface of the sensor head 10.

[0042] The clamp portion 20 includes an upper clamp member 21 and a lower clamp member 22. The upper clamp member 21 and the lower clamp member 22 are positioned to sandwich the pipe P and are connected to each other by a plurality of clamp fixing screws 23. This attaches the clamp portion 20 to the outer surface of the pipe P. As shown by the dashed arrows in Figure 1, two sensor fixing screws 101 are screwed through the sensor head 10 into the upper surface of the upper clamp member 21. This holds the sensor head 10 in place by the clamp portion 20 with its lower surface in contact with the pipe P.

[0043] The display unit 30 includes a housing 31, a connector 32, a control unit 33, a memory element 34, an operation unit 35, a display unit 36, an indicator light 37, connection ports 38, 39, and a power supply circuit 40. The housing 31 has a substantially rectangular parallelepiped shape and can be mounted on the upper surface of the sensor head 10 as shown by the dotted arrow in Figure 1. The control unit 33, the memory element 34, and the power supply circuit 40 are provided inside the housing 31.

[0044] Connector 32 is provided on the lower surface of the housing 31. By connecting connector 12 and connector 32, the display unit 30 and the sensor head 10 can communicate. In this embodiment, connector 12 and connector 32 are connected in two ways: directly and indirectly. When connector 12 and connector 32 are directly connected, the housing 31 is attached to the upper surface of the sensor head 10, thereby connecting connector 12 and connector 32. When connector 12 and connector 32 are connected via a cable (not shown), the housing 31 may be attached to the sensor head 10 or detached from the sensor head 10. In other words, because connector 12 and connector 32 are connected in two ways, the display unit 30 is detachably attached to the sensor head 10, and the connector 32 of the display unit 30 and the connector 12 of the sensor head 10 are connected.

[0045] The control unit 33 includes, for example, a CPU (Central Processing Unit) and a memory unit. The control unit 33 controls the operation of the memory element 34, the display unit 36, and the indicator light 37. The control unit 33 also compares the flow rate calculated by the sensor head 10 with a predetermined threshold and generates a switching signal based on the comparison result. Therefore, the generated switching signal is a binarized signal indicating whether the flow rate value calculated by the sensor head 10 is in a state where the flow rate value is greater than or equal to a predetermined threshold, or in a state where the flow rate value is less than a predetermined threshold. This switching signal is used by an external device capable of controlling other devices to switch the on and off states of those other devices according to the flow rate of the fluid flowing through the pipe P. In this way, when other devices are controlled according to the flow rate of the fluid flowing through the pipe P, the ultrasonic flow sensor 100 can be said to function as a flow switch that changes the operating state of other devices based on whether or not a fluid with a flow rate greater than or equal to a threshold is flowing in the pipe P.

[0046] In this embodiment, the switching signal is generated by comparing the flow rate value calculated by the sensor head 10 with a predetermined threshold value. However, any control that reflects whether the flow rate of the fluid flowing through the pipe P is above a certain amount or below a certain amount in the switching signal is acceptable. As will be described later, in this example, the flow rate value calculated by the sensor head 10 is calculated based on the fluid velocity calculated by the sensor head 10 and the cross-sectional area of ​​the pipe P. For example, a configuration in which the calculated velocity is compared with a threshold value related to the velocity and a switching signal is generated may also be used.

[0047] The memory element 34 includes, for example, a ring buffer. The memory element 34 sequentially stores log data, which associates the time with the flow rate calculated by the sensor head 10, at predetermined time intervals. The log data may include the maximum flow rate, minimum flow rate, integrated flow rate, or the level of the switching signal. When log data is stored in the entire storage area of ​​the memory element 34, the first stored log data is overwritten with the latest log data. Therefore, log data stored in the memory element 34 is retained for a certain period of time until it is overwritten by the latest log data.

[0048] The operation unit 35 is provided on the upper surface of the housing 31 so as to be able to receive input operations from the user. In Figure 1, a plan view of the operation unit 35 is shown in a vent extending from the upper surface of the display unit 30. In this embodiment, the operation unit 35 includes a confirmation button 35a and four selection buttons 35b to 35e. The four selection buttons 35b to 35e are arranged to surround the confirmation button 35a. More specifically, when the user views the ultrasonic flow sensor 100 from a predetermined positional relationship, the selection buttons 35b, 35c, 35d, and 35e are arranged in this order above, below, left, and right relative to the confirmation button 35a. The user can input various parameters by operating the operation unit 35.

[0049] The parameters input from the control unit 35 include parameters related to initial settings for calculating the flow rate, frequently used parameters, and infrequently used parameters. Parameters related to initial settings include, for example, the material of the pipe P and the outer diameter of the pipe P according to the standard. For the convenience of the user, it is preferable that the outer diameter of the pipe P input as a parameter related to initial settings is the nominal diameter defined by the standard.

[0050] Frequently used parameters include, for example, response time, display resolution, hysteresis, zero-cut flow rate, direction of fluid flow, and the period for detecting microbubble density (described later). These frequently used parameters are related to the switching signal. Therefore, when the user adjusts the output based on the actual output results from the ultrasonic flow sensor 100, they are set to arbitrary values.

[0051] Infrequently used parameters include, for example, the flow rate calculation mode, the outer diameter of pipe P, the thickness of pipe P, the speed of sound in pipe P, and the kinematic viscosity of the fluid. These parameters affect the flow rate value calculated by the sensor head 10. Therefore, infrequently used parameters are changed to arbitrary values ​​when the user adjusts the values ​​in the process leading up to the output of the ultrasonic flow sensor 100, rather than the output itself.

[0052] Furthermore, the parameters related to the dimensions of the piping P, which are included in the parameters used infrequently, are parameters whose values ​​are changed when the user fine-tunes the value corresponding to the nominal diameter. Some or all of the above parameters may be entered via selection. The parameters entered from the operation unit 35 are provided to the sensor head 10. In addition, the user can input a desired threshold value for the flow rate by operating the operation unit 35.

[0053] In addition to the above example, the parameters that can be input from the operation unit 35 may include multiple monitoring ranges (such as the first to fourth ranges TA1 to TA4 on the time axis in Figure 8) used in the abnormality diagnosis process described later.

[0054] The display unit 36 ​​is provided on the upper surface of the housing unit 31. The display unit 36 ​​displays the fluid flow rate calculated by the sensor head 10. In other words, since the display unit 30 equipped with the display unit 36 ​​that displays the flow rate is detachable from the sensor head 10, the user can visually check the flow rate of the portion of the piping P where the sensor head 10 is installed at a suitable position by positioning the display unit 30 in a suitable position.

[0055] Furthermore, in the ultrasonic flow sensor 100 according to this embodiment, multiple types of abnormality determinations are performed to determine whether or not an abnormality has occurred in the flow measurement state by the ultrasonic flow sensor 100. The display unit 36 ​​then displays the result of the abnormality determination. Details of the abnormality determination and the display of the determination result on the display unit 36 ​​will be described later.

[0056] The indicator light 37 includes, for example, multiple light-emitting diodes that emit light in different colors, and is provided on the upper surface of the housing 31. The indicator light 37 lights up or flashes in a manner that allows for the identification of the level of the switching signal generated by the control unit 33. That is, the indicator light 37 lights up or flashes in a manner that allows for the identification of an indication that the flow rate of the fluid flowing through the pipe P is above a certain amount, and an indication that the flow rate of the fluid flowing through the pipe P is below a certain amount. Similar to the display unit 36, the indicator light 37 is provided on the display unit 30, so that the user can visually confirm the flow rate status of the portion of the pipe P where the sensor head 10 is provided at a suitable position.

[0057] Connection port 38 includes, for example, a USB (Universal Serial Bus) port and is provided on the side of the housing 31. When connection port 38 is connected to an external information processing device via a cable (not shown), log data stored in memory element 34 is output to the information processing device. Connection port 39 includes, for example, an M12 port and is provided on the end face of the housing 31. When connection port 39 is connected to an external device such as a personal computer or a programmable logic controller via a cable (not shown), a switching signal generated by the control unit 33 is output to the external device.

[0058] The power supply circuit 40 converts the voltage supplied by the external commercial power supply into a voltage suitable for the ultrasonic flow sensor 100, and supplies the converted voltage to the control unit 33, memory element 34, display unit 36, and indicator light 37. The power supply circuit 40 also supplies the converted voltage to each part of the sensor head 10 through the connector 32.

[0059] Figure 2 is a schematic cross-sectional view showing the configuration of the sensor head 10 in Figure 1. As shown in Figure 2, the sensor head 10 includes a housing 11, a connector 12, a control board 13, two wedge materials 14, two ultrasonic elements 15, an acoustic couplant 16, an ultrasonic shielding plate 17, and an indicator light 18.

[0060] The housing 11 has a roughly rectangular parallelepiped shape with an opening at the bottom. A connector 12 is exposed on the top surface of the housing 11. A wedge material 14 is exposed at the opening at the bottom of the housing 11. The housing 11 houses the control board 13 and the ultrasonic element 15.

[0061] The connector 12 is provided on the upper surface of the housing 11. As described above, the connector 12 is positioned so that it can be connected to the connector 32 when the housing 31 of the display unit 30 in Figure 1 is attached to the housing 11.

[0062] The control board 13 includes a transmitting circuit 131, a receiving circuit 132, and a control unit 133, and is located inside the housing 11. The transmitting circuit 131 outputs a drive signal to each of the two ultrasonic elements 15 for transmitting ultrasonic waves. The receiving circuit 132 includes an amplification circuit and amplifies the signal output by each of the two ultrasonic elements 15 upon receiving ultrasonic waves. The receiving circuit 132 also includes an A / D (analog-to-digital) converter and converts the analog signals output from each of the two ultrasonic elements 15 into digital signals, which are then supplied to the control unit 133.

[0063] The control unit 133 includes, for example, a CPU and a memory unit 331 (Figure 23), and controls the operation of the transmission circuit 131, the reception circuit 132, and the indicator light 18. The memory unit 331 stores a flow rate measurement program for calculating the flow rate of fluid in the piping P. The memory unit 331 also stores an abnormality diagnosis program for determining whether or not an abnormality has occurred in the flow rate measurement state.

[0064] The control unit 133 executes a flow rate measurement program and an anomaly diagnosis program. In this case, the control unit 133 operates each of the two ultrasonic elements 15 by controlling the transmitting circuit 131 and the receiving circuit 132. When the flow rate measurement program is executed, the control unit 133 calculates the flow rate of the fluid flowing through the piping P based on various signals obtained from the two ultrasonic elements 15 and predetermined parameters. Details of the flow rate calculation method will be described later.

[0065] Furthermore, when the abnormality diagnosis program is executed, the control unit 133 determines whether or not an abnormality has occurred in the flow rate measurement state based on various signals obtained from the two ultrasonic elements 15 and predetermined parameters. Details of the method for determining whether or not an abnormality has occurred in the flow rate measurement state will be described later.

[0066] Each wedge material 14 is positioned between each ultrasonic element 15 and the piping P when the sensor head 10 is attached to the clamp portion 20. Each wedge material 14 is made of a non-metallic material that has high rigidity and high acoustic transparency. Preferably, each wedge material 14 is made of a material with high environmental resistance. In this example, each wedge material 14 is made of PPS (polyphenylene sulfide) resin and PEEK (polyether ether ketone) resin, but it may also be made of ULTEM® resin. Each wedge material 14 has an element coupling surface 14a facing diagonally upward and a piping coupling surface 14b facing downward.

[0067] In the following description, when distinguishing between the two wedge materials 14, one wedge material 14 will be referred to as wedge material 14A, and the other wedge material 14 as wedge material 14B. The wedge materials 14A and 14B are arranged in the longitudinal direction of the housing 11 with their element coupling surfaces 14a facing diagonally upward and outward, and are attached to the opening at the bottom of the housing 11. This creates a space inside the housing 11 that prevents the ingress of liquids such as water and oil.

[0068] Each ultrasonic element 15 is configured to operate selectively between transmission mode and reception mode. In transmission mode, the ultrasonic element 15 transmits ultrasound by receiving a drive signal from the transmission circuit 131. In reception mode, the ultrasonic element 15 receives ultrasound from an external source and outputs an analog signal indicating the intensity of the received ultrasound. Each ultrasonic element 15 may be composed of a composite element. In this case, since the reverberation time of the transmitted ultrasound is short, noise is reduced when the same ultrasonic element 15 operates in transmission mode and then in reception mode. In the pulse Doppler method described later, it is preferable that the ultrasonic element 15 transmitting the ultrasound receives the ultrasound signal reflected by the reflector in order to receive the ultrasound signal reflected by the reflector at a position where the intensity of the ultrasound signal is high. Therefore, in the pulse Doppler method, it is preferable that the ultrasonic element 15 is a composite element in order to improve the received intensity of the ultrasound signal. Note that even in the propagation time difference method, there is a certain effect because the noise is reduced when operating in transmission mode and then in reception mode.

[0069] In the following description, when distinguishing between the two ultrasonic elements 15, one ultrasonic element 15 will be referred to as ultrasonic element 15A, and the other ultrasonic element 15 as ultrasonic element 15B. The ultrasonic elements 15A and 15B are joined to the element bonding surfaces 14a of the wedge materials 14A and 14B, respectively. As a result, the ultrasonic elements 15A and 15B are installed inside the housing portion 11 at a predetermined angle with respect to the piping P.

[0070] The acoustic couplant 16 has a solid shape and is made of a soft elastic material such as polymer rubber or a gel-like substance. The acoustic couplant 16 is provided at the bottom of the housing portion 11 so as to contact the pipe coupling surface 14b of each wedge material 14. The lower surface of the acoustic couplant 16 protrudes slightly from the lower surface of the housing portion 11. The acoustic couplant 16 matches the acoustic impedance between each wedge material 14 and the pipe P by contacting the pipe P with its lower surface. Therefore, it is preferable that the acoustic couplant 16 has an acoustic impedance value between the acoustic impedance value of each wedge material 14 and the acoustic impedance value of the pipe P.

[0071] The ultrasonic shielding plate 17 is made of, for example, foamed rubber and has a flat plate shape. The ultrasonic shielding plate 17 is positioned between the wedge materials 14A and 14B so as to penetrate the acoustic couplant 16 when it is upright. In this case, the direct transmission of ultrasonic components that do not pass through the pipe P between the wedge materials 14A and 14B is prevented.

[0072] The indicator light 18 includes, for example, multiple light-emitting diodes and lights up or flashes in a manner that allows the user to identify the level of the switching signal, similar to the indicator light 37 of the display unit 30. Therefore, when the display unit 30 is directly connected to the sensor head 10, the user can easily identify the level of the switching signal by looking at the indicator light 37 of the display unit 30. On the other hand, the display unit 30 can be separated from the sensor head 10 by connecting the display unit 30 and the sensor head 10 with a cable. In this state, the user can install the display unit 30 on any mounting surface. Even when the display unit 30 is separated from the sensor head 10, the user can easily identify the level of the switching signal by looking at the indicator light 18 of the sensor head 10.

[0073] As described above, the sensor head 10 is fixed to the clamp portion 20 in Figure 1 by two sensor fixing screws 101. This allows the sensor head 10 to be attached to the pipe P while the acoustic couplant 16 is pressed against the pipe P. In this state, the sensor head 10 operates. The operation of the sensor head 10 will be described below.

[0074] [2] Operation of the sensor head The user can select one of the following flow rate calculation modes for the sensor head 10 by operating the control unit 35 in Figure 1: propagation time difference mode, pulse Doppler mode, or hybrid mode. In propagation time difference mode, the sensor head 10 operates using the propagation time difference method to calculate the flow rate. In pulse Doppler mode, the sensor head 10 operates using the pulse Doppler method to calculate the flow rate. In hybrid mode, the sensor head 10 operates using both the propagation time difference method and the pulse Doppler method to calculate the flow rate.

[0075] Figure 3 is a diagram illustrating the operation of the sensor head 10 in the propagation time difference method. In the propagation time difference method, first the ultrasonic element 15A transmits ultrasonic waves, and the ultrasonic element 15B receives ultrasonic waves. The ultrasonic waves transmitted diagonally downward by the ultrasonic element 15A are incident on the wedge material 14A as shown by arrow A1. The ultrasonic waves incident on the wedge material 14A pass through the acoustic couplant 16 and are incident on the fluid in the pipe P as shown by arrow A2. The ultrasonic waves that have passed through the fluid are reflected by the inner wall of the pipe P and propagate through the fluid in the direction of arrow A3. The ultrasonic waves propagating in the direction of arrow A3 pass through the acoustic couplant 16 and are incident on the wedge material 14B as shown by arrow A4. The ultrasonic waves incident on the wedge material 14B are received by the ultrasonic element 15B. The control unit 133 measures the propagation time AB from the time the ultrasonic waves transmitted by the ultrasonic element 15A are received by the ultrasonic element 15B.

[0076] After ultrasonic element 15B receives ultrasonic waves transmitted from ultrasonic element 15A, ultrasonic element 15B transmits ultrasonic waves, and ultrasonic element 15A receives ultrasonic waves transmitted from ultrasonic element 15B. The ultrasonic waves transmitted diagonally downward by ultrasonic element 15B are incident on the wedge material 14B as indicated by arrow B1. The ultrasonic waves incident on the wedge material 14B pass through the acoustic couplant 16 and are incident on the fluid in pipe P as indicated by arrow B2. The ultrasonic waves that have passed through the fluid are reflected by the inner wall of pipe P and propagate through the fluid in the direction of arrow B3. The ultrasonic waves propagating in the direction of arrow B3 pass through the acoustic couplant 16 and are incident on the wedge material 14A as indicated by arrow B4. The ultrasonic waves incident on the wedge material 14A are received by ultrasonic element 15A. The control unit 133 measures the propagation time BA from when the ultrasonic waves transmitted by ultrasonic element 15B are received by ultrasonic element 15A.

[0077] After measuring propagation times AB and BA, the control unit 133 of the control board 13 measures the propagation time difference Δt. The propagation time difference Δt is the difference between propagation time AB and propagation time BA. Based on the propagation time difference Δt, the control unit 133 calculates the flow rate V of the fluid flowing through the pipe P using the following equation (1).

[0078] Here, C' is the velocity of the ultrasonic waves in the wedge material 14, and θ' is the angle of incidence of the ultrasonic waves onto the wedge material 14. C is the velocity of the ultrasonic waves in the fluid, and θ is the angle of incidence of the ultrasonic waves onto the fluid. d is the inner diameter of the pipe P, and λ is the pipe friction coefficient (Blasius coefficient). The velocity C', the angle of incidence θ', the angle of incidence θ, and the Blasius coefficient are known and stored as predetermined parameters in the memory unit 331 (Figure 23) of the control unit 133.

[0079] In the calculation of flow rate using the propagation time difference method in propagation time difference mode, the velocity C and the inner diameter d of the pipe P are input by the user. Note that d in equation (1) or equation (2) described later 2 π / 4 is the cross-sectional area of ​​pipe P, and the value obtained by dividing the flow rate V by the cross-sectional area is the flow velocity of the fluid flowing through pipe P.

[0080]

number

[0081] Thus, in the propagation time difference method, two ultrasonic elements are required: one that transmits an ultrasonic signal that propagates along the direction of fluid flow, and another that transmits an ultrasonic signal that propagates against the direction of fluid flow. Each of these ultrasonic elements is positioned to receive the ultrasonic signal transmitted from the other ultrasonic element. In this example, since both ultrasonic elements 15A and 15B are positioned above the pipe P, the ultrasonic elements 15 can be positioned by working from one side of the pipe P. In particular, in this example, since both ultrasonic elements 15A and 15B are housed in the housing 11, the installation of the sensor head 10 is easy.

[0082] In this embodiment, the speed C is input by the user, but the speed of sound in the pipe P may also be input. Since the value of the speed of sound in pipe P, which is determined from the material of pipe P, does not deviate much from the actual value, the user can easily input a highly accurate value by referring to a table that correlates the material of pipe P with the speed of sound. Furthermore, although the speed of sound in pipe P is used to calculate the propagation time in the fluid from the propagation time from one ultrasonic element 15 to the other, the proportion of pipe P in the propagation path from one ultrasonic element 15 to the other is small, so the error in the ultrasonic propagation speed in pipe P has little effect on the calculated flow rate V. For this reason, the accuracy required for the value input by the user is low, and the user can input the value in a simple manner. In the example where the speed of sound in pipe P is input, the speed of the ultrasonic signal in the fluid is calculated using the propagation time difference method after the propagation time of the ultrasonic signal in the fluid. Since this speed is a value that approximates the speed C, a flow rate V that approximates the flow rate V when speed C is input is calculated. In this way, by appropriately changing the input value, the burden on the user who inputs the value can be reduced. The speed of sound in the pipe P may be calculated by the control unit 133 based on the user's selection of the material of the pipe P and the nominal diameter defined by the standard.

[0083] Figure 4 is a diagram illustrating the operation of the sensor head 10 in the pulsed Doppler method. In the pulsed Doppler method, the operating mode of the ultrasonic element 15B alternates between transmission mode and reception mode. In transmission mode, the ultrasonic element 15B transmits a pulsed ultrasonic signal consisting of several pulses. The ultrasonic waves transmitted diagonally downward by the ultrasonic element 15B are incident on the wedge material 14B as indicated by arrow C1. The ultrasonic waves incident on the wedge material 14B pass through the acoustic couplant 16 and are incident on the fluid in the pipe P as indicated by arrow C2.

[0084] Here, the fluid flowing through pipe P contains microbubbles as reflectors that reflect ultrasonic waves. Microbubbles are, for example, tiny bubbles with a diameter of 10 μm to 50 μm. Microbubbles are also likely to occur in coolant fluids such as water-soluble cutting fluids that cool the machining points of machine tools. Coolant fluids contain surfactants, and since they are circulated and reused after coming into contact with air, a large number of microbubbles are likely to occur in the coolant fluid flowing through pipe P, which constitutes part of the circulation system.

[0085] A portion of the ultrasonic waves reflected by the microbubbles passes through the acoustic couplant 16, as indicated by arrow C3, and is incident on the wedge material 14B, as indicated by arrow C4. The ultrasonic waves incident on the wedge material 14B are received by the ultrasonic element 15B in receiving mode. Thus, in the pulsed Doppler method, the time it takes for the ultrasonic waves transmitted from the ultrasonic element 15B to be reflected by the microbubbles and reach the ultrasonic element 15B is short and determined by the position of the microbubbles, so it is preferable that the ultrasonic element 15B is a composite element with a short reverberation time.

[0086] The control unit 133 measures the Doppler frequency Δf. The Doppler frequency Δf is the difference between the frequency of the ultrasound transmitted by the ultrasonic element 15B and the frequency of the ultrasound received by the ultrasonic element 15B, and is proportional to the flow velocity of the microbubbles flowing through the pipe P, i.e., the fluid flow velocity. Based on the measured Doppler frequency Δf, the control unit 133 calculates the flow rate V of the fluid flowing through the pipe P using the following equation (2). Here, f is the frequency of the ultrasound transmitted by the ultrasonic element 15B. The frequency f is known and is stored as a predetermined parameter in the memory unit 331 of the control unit 133. Details of the frequency f will be described later.

[0087]

number

[0088] Thus, in the pulsed Doppler method, it is sufficient to measure the frequency of the ultrasonic signal when a pulsed ultrasonic signal is transmitted to a fluid and reflected by a reflector contained in the fluid. In this example, a single ultrasonic element 15B transmits a pulsed ultrasonic signal and measures the frequency of the ultrasonic signal reflected by microbubbles, thus minimizing the number of ultrasonic elements required for the pulsed Doppler method and contributing to the miniaturization of the sensor head 10. In particular, in this example, the ultrasonic element 15B is composed of a composite element and has a short reverberation time, so when measuring the frequency of the ultrasonic signal reflected by microbubbles, the influence of reverberation when the ultrasonic signal was transmitted is less likely to occur.

[0089] Furthermore, the sensor head 10, which calculates flow rate using the pulsed Doppler method, may also include an ultrasonic element that measures the frequency of ultrasound reflected by a reflector, in addition to the ultrasonic element that transmits the ultrasonic signal. In this case, since the ultrasonic element that measures the frequency is a different ultrasonic element from the ultrasonic element that transmits the ultrasonic signal, a decrease in detection accuracy due to reverberation is less likely to occur.

[0090] Figure 5 is a diagram illustrating the operation of the sensor head 10 in a more specific way using the pulsed Doppler method. As shown in Figure 5, the fluid does not flow at a uniform velocity through the flow path of pipe P, but rather flows with a predetermined velocity distribution. The flow velocity of the fluid flowing near the center of the flow path of pipe P is greater than the flow velocity of the fluid flowing near the inner wall of pipe P.

[0091] In the pulsed Doppler method, the time it takes for the ultrasonic waves transmitted by the ultrasonic element 15B to reach the microbubble, and the time it takes for the ultrasonic waves reflected by the microbubble to reach the ultrasonic element 15B, differ depending on the depth to which the microbubble flows. In this example, the depth to which the microbubble flows is the position of the microbubble in the radial direction of the pipe P. Therefore, the control unit 133 measures the Doppler frequency for each time interval from when the ultrasonic waves are transmitted until the ultrasonic waves reflected by the microbubble are received.

[0092] In this embodiment, the connector 12 is positioned closer to the ultrasonic element 15A than to the ultrasonic element 15B. In other words, the distance between the connector 12 and the ultrasonic element 15A is smaller than the distance between the connector 12 and the ultrasonic element 15B. The power supply circuit 40 is provided near the part of the control board 13 to which the connector 12 is connected. In the pulsed Doppler method, the frequency of the ultrasonic signal received by the ultrasonic element 15 is easily affected by the power supply circuit 40. For this reason, it is preferable that the ultrasonic element 15B, which is relatively far from the connector 12, receives the ultrasonic signal in the pulsed Doppler method.

[0093] Figure 6 shows the relationship between the detected ultrasonic signal intensity and the Doppler frequency over time. The horizontal axis in Figure 6 represents the Doppler frequency. The vertical axis in Figure 6 represents the ultrasonic signal intensity. In the example in Figure 6, waveforms S1 to S4 corresponding to multiple time points are shown by solid, dotted, dashed, and double-dash lines, respectively. Waveforms S1 to S4 are the waveforms detected for ultrasonic waves reflected by microbubbles flowing at depths d1 to d4 in Figure 5, and are detected at multiple different time points t1 to t4.

[0094] The control unit 133 measures the centroid position of waveforms S1 to S4 as the Doppler frequency corresponding to depths d1 to d4. The control unit 133 also calculates the fluid (microbubble) velocity at each depth d1 to d4 based on the measured Doppler frequencies. As described above, the fluid velocity is calculated as the value obtained by dividing the flow rate V in equation (2) by the cross-sectional area.

[0095] Thus, in the pulsed Doppler method, the position of the fluid (microbubbles) can be spatially resolved, and the fluid velocity distribution can be identified. In the examples in Figures 5 and 6, the fluid velocity is calculated for each depth d1 to d4, but the number of depth points may be appropriately determined according to the diameter of the pipe P or the processing speed of the control unit 133. The control unit 133 averages the identified fluid velocity distribution and calculates the fluid flow rate by multiplying the averaged velocity distribution by the cross-sectional area of ​​the flow path in the pipe P.

[0096] In hybrid mode, the sensor head 10 alternately performs the propagation time difference method and the pulsed Doppler method. The operating period for the propagation time difference method and the operating period for the pulsed Doppler method are, for example, 150 ms each, but the embodiment is not limited to this. The operating period for the propagation time difference method or the operating period for the pulsed Doppler method may be shorter or longer than 150 ms. Also, the operating period for the propagation time difference method and the operating period for the pulsed Doppler method do not have to be the same.

[0097] In this example, the ultrasonic element 15B transmits and receives ultrasonic signals using the propagation time difference method, and also transmits pulsed ultrasonic signals using the pulsed Doppler method, and measures the frequency of the ultrasonic waves reflected by the reflector. With this configuration, the number of ultrasonic elements can be minimized in the sensor head 10, which is capable of calculating flow rate using both the propagation time difference method and the pulsed Doppler method, thus having a certain effect on miniaturizing the sensor head 10.

[0098] A sensor head 10 capable of calculating flow rate using both the propagation time difference method and the pulsed Doppler method may have a configuration in which ultrasonic elements used for flow rate calculation using the propagation time difference method and ultrasonic elements used for flow rate calculation using the pulsed Doppler method are provided separately. For example, in this embodiment, ultrasonic elements 15A and 15B are used only for flow rate calculation using the propagation time difference method, and ultrasonic elements used for flow rate calculation using the pulsed Doppler method are provided separately. In this configuration, the ultrasonic elements used for flow rate calculation using the propagation time difference method are not used for flow rate calculation using the pulsed Doppler method, and the ultrasonic elements used for flow rate calculation using the pulsed Doppler method are not used for flow rate calculation using the propagation time difference method. Therefore, in the hybrid mode with this configuration, the operating period for the propagation time difference method and the operating period for the pulsed Doppler method may overlap, and the system is less susceptible to changes in flow rate during the switching between operating periods.

[0099] Figure 7 shows the fluid flow rates calculated using the propagation time difference method and the pulsed Doppler method. The horizontal axis of Figure 7 represents the density of microbubbles contained in the fluid relative to the actual flow rate. The vertical axis of Figure 7 represents the relative value of the calculated fluid flow rate. The flow rate measured using the propagation time difference method is shown by a thick solid line, and the flow rate measured using the pulsed Doppler method is shown by a thin solid line.

[0100] As shown in Figure 7, in the propagation time difference method, 100% of the flow rate can be calculated when the microbubble density is relatively low. However, when the microbubble density is relatively high, the flow rate cannot be calculated. On the other hand, in the pulsed Doppler method, a flow rate close to 100% can be calculated when the microbubble density is relatively high. In particular, the flow rate can be calculated with relatively high accuracy when the microbubble density is between value V1 and value V2, which is higher than value V1.

[0101] Therefore, in hybrid mode, the control unit 133 treats the calculated flow rate as a composite of the flow rate calculated by the propagation time difference method and the flow rate calculated by the pulse Doppler method. Consequently, in hybrid mode, the switching signal described above is generated based on a flow rate value that is a composite of the flow rate value calculated by the propagation time difference method and the flow rate value calculated by the pulse Doppler method, and the indicator light 37 lights up or blinks based on a flow rate value that is a composite of the flow rate value calculated by the propagation time difference method and the flow rate value calculated by the pulse Doppler method.

[0102] In hybrid mode, the control unit 133 determines the combined ratio of the flow rate calculated by the propagation time difference method and the flow rate calculated by the pulsed Doppler method, based on the stability of the flow rate calculation. The stability of the flow rate calculation includes, for example, the signal intensity of the detected ultrasonic waves. In hybrid mode, the control unit 133 may also correct the calculated flow rate based on parameters such as the outer diameter of the pipe P or the kinematic viscosity of the fluid.

[0103] [3] Abnormality in the flow rate measurement status by the ultrasonic flow sensor 100 In the ultrasonic flow sensor 100 having the above configuration, the flow rate of the fluid in the piping P may become impossible to measure or the measurement accuracy may be significantly reduced due to various reasons. In such cases, when flow rate measurement is impossible or the measurement accuracy is significantly reduced, i.e., when an abnormality occurs in the flow rate measurement state, the user must identify the cause of the abnormality and perform recovery work according to that cause. The possible causes of abnormalities in the flow rate measurement state are explained below.

[0104] Figures 8 to 12 are diagrams illustrating possible causes of abnormalities in the flow rate measurement state by the ultrasonic flow sensor 100. The upper part of Figure 8 shows a schematic cross-sectional view of the state in which ultrasonic waves emitted from one ultrasonic element 15A toward pipe P are properly incident on the fluid FL inside pipe P through the wedge material 14A, acoustic couplant 16, and pipe P. The lower part of Figure 8 shows a graph of ultrasonic waveforms obtained by alternately switching the operating mode of the ultrasonic element 15A between transmission mode and reception mode. In the graph in the lower part of Figure 8, the horizontal axis represents time, and the vertical axis represents the ultrasonic signal intensity (voltage). The horizontal axis (time axis) corresponds to the path of the ultrasonic waves shown by the thick solid line in the upper part of Figure 8.

[0105] (1) Abnormality of the ultrasonic element 15 When ultrasound is properly transmitted into the pipe P, as shown in Figure 8, a waveform with a relatively large signal intensity is generated in the first range TA1 of the time axis corresponding to a portion of the ultrasound path between the ultrasound element 15A and the wedge material 14A (for example, the portion within the upper ellipse UP1). However, if ultrasound is not emitted from the ultrasound element 15A or the intensity of the emitted ultrasound is significantly reduced due to deterioration of the ultrasound element 15A, as shown in Figure 9, the ultrasound cannot reach the fluid FL in the pipe P. Therefore, in order to transmit ultrasound from the sensor head 10 into the pipe P, it is necessary to replace the ultrasound element 15 with a properly functioning ultrasound element 15. In the following explanation, an abnormality in the measurement state caused by the ultrasound element 15 will be referred to as an "element abnormality".

[0106] (2) Abnormalities in the installation condition When ultrasound is properly transmitted into pipe P, as shown in Figure 8, a waveform with a relatively small signal intensity is generated in a second range TA2 of the time axis corresponding to a portion of the ultrasound path that includes the outer surface of pipe P (for example, the portion within the upper ellipse UP2). This waveform is caused by the difference in acoustic impedance between the wedge material 14 and pipe P. As shown in Figure 10, if a gap is formed between, for example, the acoustic couplant 16 and pipe P, the acoustic impedance between the wedge material 14 and pipe P does not match. In this case, a waveform with a significantly large signal intensity is generated in the second range TA2, and almost no ultrasound is transmitted into pipe P. Therefore, in order to transmit ultrasound from the sensor head 10 into pipe P, the acoustic couplant 16 must be in close contact with the outer surface of pipe P. In the following description, an abnormality in the measurement state caused by the mounting state of the sensor head 10 to pipe P will be referred to as an "mounting abnormality".

[0107] (3) Abnormality when the pipe P is not filled with fluid When ultrasound is properly transmitted into pipe P, as shown in Figure 8, a waveform with a relatively small signal intensity is generated in the third range TA3 of the time axis corresponding to a portion of the ultrasound path that includes the inner surface of pipe P (for example, the portion within the upper ellipse UP3). This waveform is caused by the difference in acoustic impedance between pipe P and fluid FL. Therefore, as shown in Figure 11, if a layer of air AR exists in the ultrasound path because pipe P is not filled with fluid FL, a waveform with a significantly large signal intensity is generated in the third range TA3, and almost no ultrasound is transmitted to the fluid FL in pipe P. Consequently, in order to transmit ultrasound from the sensor head 10 to the fluid FL in pipe P, it is necessary to change the mounting position of the sensor head 10 relative to pipe P or change the orientation of the sensor head 10. In the following description, an abnormality in the measurement state caused by insufficient filling of fluid FL in pipe P will be referred to as a "non-filling abnormality".

[0108] (4) Abnormality when an excessive amount of bubbles are present in the fluid FL When ultrasound is properly transmitted into pipe P, as shown in Figure 8, a waveform with extremely low signal intensity is generated in the fourth time range TA4, which corresponds to a portion of the ultrasound path within pipe P (for example, the portion within the upper ellipse UP4). This waveform is the waveform of the ultrasound traveling through the fluid FL. Therefore, if there is nothing obstructing the propagation of ultrasound within the fluid FL, its signal level will be equivalent to the noise level.

[0109] However, as shown in Figure 12, if, for example, an excessive amount of microbubbles is present in the fluid FL, i.e., if the microbubble density in the fluid FL is extremely high, the ultrasound propagating through the fluid FL will be significantly attenuated. Such significant attenuation of ultrasound makes it impossible to calculate the fluid FL flow rate using the pulsed Doppler method explained with Figure 7.

[0110] Therefore, when measurement errors occur due to microbubbles in the fluid FL, it is necessary to change the mounting position and orientation of the sensor head 10 relative to the pipe P so that ultrasonic waves are transmitted towards areas with low microbubble density inside the pipe P. Alternatively, if the high density of microbubbles in the fluid FL is due to the fluid velocity of the fluid FL, it is necessary to change the velocity of the fluid FL flowing through the pipe P. In the following explanation, an abnormality in the measurement state caused by the presence of an excessive amount of bubbles in the fluid FL will be referred to as a "bubble abnormality."

[0111] [4] Abnormality diagnosis function for measurement status As described above, there are several possible causes for abnormalities in the flow rate measurement. Therefore, if any abnormality occurs in the flow rate measurement, the user must identify the cause of the abnormality and take appropriate action to resolve it. However, it is not easy to identify the cause of an abnormality when the sensor head 10 is attached to the piping P.

[0112] Therefore, the ultrasonic flow sensor 100 according to this embodiment has an abnormality diagnosis function that determines whether or not there is an abnormality in the flow measurement state in response to the user's request and identifies the type of abnormality.

[0113] When the abnormality diagnosis function is used, the fluid flow rate measurement operation of the ultrasonic flow sensor 100 is temporarily stopped. In this state, for each of the two ultrasonic elements 15, multiple abnormality judgments corresponding to multiple types of abnormalities are performed in the following order. The order of multiple abnormality judgments corresponding to multiple types of abnormalities described below corresponds to an example of a sequence pre-set in the diagnostic mode of the present invention.

[0114] (1) Component abnormality detection The presence or absence of an element abnormality is determined. During this determination, for example, one of the ultrasonic elements 15 operates by switching alternately between transmission mode and reception mode. As a result, a portion of the ultrasonic waveform acquired when the ultrasonic element 15 is in reception mode that is located within a first range TA1 (Figure 8) on the time axis is extracted. It is determined whether or not the intensity of the extracted ultrasonic waveform is above a predetermined first threshold.

[0115] If the intensity of the extracted ultrasonic waveform is equal to or greater than a first threshold, it is determined that no element abnormality has occurred, i.e., one of the ultrasonic elements 15 is normal. If the intensity of the extracted ultrasonic waveform is less than the first threshold, it is determined that an element abnormality has occurred in one of the ultrasonic elements 15. This determination operation is performed similarly for the other ultrasonic element 15 after the determination for one ultrasonic element 15 has been completed.

[0116] The first threshold value and the first range TA1 are parameters predetermined according to the specifications of the ultrasonic element 15, and are stored in the storage unit 331 (Figure 23) of the control unit 133 at the time of factory shipment of the ultrasonic flow sensor 100. Furthermore, the first range TA1 may be stored in the storage unit 331 of the control unit 133 by the user operating the operation unit 35 of the display unit 30. In addition, the first threshold value and the first range TA1 stored in the storage unit 331 of the control unit 133 may be changed by the user operating the operation unit 35.

[0117] (2) Installation abnormality detection The presence or absence of an installation abnormality is determined. During this determination, for example, one of the ultrasonic elements 15 operates by switching alternately between transmission mode and reception mode. As a result, a portion of the acquired ultrasonic waveform that is located within a second range TA2 (Figure 8) on the time axis is extracted. It is determined whether or not the intensity of the extracted ultrasonic waveform is below a predetermined second threshold.

[0118] If the intensity of the extracted ultrasonic waveform is below the second threshold, it is determined that there is no installation abnormality, i.e., one of the ultrasonic elements 15 is properly installed in the piping P. If the intensity of the extracted ultrasonic waveform is greater than the second threshold, it is determined that an installation abnormality has occurred in one of the ultrasonic elements 15. This determination operation is performed for the other ultrasonic element 15 after the determination for one ultrasonic element 15 has been completed.

[0119] The second threshold value and the second range TA2 are parameters predetermined according to the specifications of the ultrasonic element 15, and are stored in the storage unit 331 of the control unit 133 at the time of factory shipment of the ultrasonic flow sensor 100. Furthermore, the second range TA2 may be stored in the storage unit 331 of the control unit 133 by the user operating the operation unit 35 of the display unit 30. In addition, the second threshold value and the second range TA2 stored in the storage unit 331 of the control unit 133 may be changed by the user operating the operation unit 35.

[0120] (3) Determination of abnormal non-filling The presence or absence of a non-charge abnormality is determined. During this determination, for example, one of the ultrasonic elements 15 operates by switching alternately between transmission mode and reception mode. As a result, a portion of the acquired ultrasonic waveform that is located within a third range TA3 (Figure 8) on the time axis is extracted. It is determined whether or not the intensity of the extracted ultrasonic waveform is below a predetermined third threshold.

[0121] If the intensity of the extracted ultrasonic waveform is below the third threshold, it is determined that no non-filling abnormality has occurred, that is, the pipe P is filled with fluid FL, and the ultrasonic waves transmitted from one ultrasonic element 15 are being properly transmitted to the fluid FL inside the pipe P. If the intensity of the extracted ultrasonic waveform is greater than the third threshold, it is determined that a non-filling abnormality has occurred for one of the ultrasonic elements 15. That is, it is determined that the ultrasonic waves transmitted from one ultrasonic element 15 are not being transmitted to the fluid FL inside the pipe P. This determination process is performed for the other ultrasonic element 15 after the determination for one ultrasonic element 15 has been completed.

[0122] The third threshold and the third range TA3 are parameters predetermined according to the specifications of the ultrasonic element 15, and are stored in the storage unit 331 of the control unit 133 at the time of factory shipment of the ultrasonic flow sensor 100. Furthermore, the third range TA3 may be stored in the storage unit 331 of the control unit 133 by the user operating the operation unit 35 of the display unit 30. In addition, the third threshold and the third range TA3 stored in the storage unit 331 of the control unit 133 may be changed by the user operating the operation unit 35.

[0123] (4) Abnormal bubble detection The presence or absence of bubble abnormalities is determined. During this determination, for example, one of the ultrasonic elements 15 operates by switching alternately between transmission mode and reception mode. As a result, a portion of the acquired ultrasonic waveform that is located within the fourth range TA4 (Figure 8) on the time axis is extracted. It is determined whether or not the intensity distribution of the extracted ultrasonic waveform conforms to predetermined conditions (hereinafter referred to as bubble conditions). Here, the bubble conditions are, for example, that the slope of the envelope of the extracted ultrasonic waveform is maintained below a predetermined fourth threshold.

[0124] If the intensity distribution of the extracted ultrasonic waveform follows the bubble condition, it is determined that no bubble abnormality has occurred, i.e., there are no excessive amounts of microbubbles in the fluid FL in pipe P. If the intensity distribution of the extracted ultrasonic waveform does not follow the bubble condition, it is determined that there are excessive amounts of microbubbles in the fluid FL in pipe P. This determination process is performed for the other ultrasonic element 15 after the determination for one ultrasonic element 15 has been completed.

[0125] The fourth threshold and the fourth range TA4 are parameters predetermined according to the specifications of the ultrasonic element 15, and are stored in the storage unit 331 of the control unit 133 at the time of factory shipment of the ultrasonic flow sensor 100. Furthermore, the fourth range TA4 may be stored in the storage unit 331 of the control unit 133 by the user operating the operation unit 35 of the display unit 30. In addition, the fourth threshold and the fourth range TA4 stored in the storage unit 331 of the control unit 133 may be changed by the user operating the operation unit 35.

[0126] (5) Determination of transmission / reception abnormalities The ultrasonic flow sensor 100 comprises two ultrasonic elements 15. For example, in the propagation time difference method, the flow rate is calculated by the transmission and reception of ultrasonic waves between the two ultrasonic elements 15. Therefore, with the sensor head 10 attached to the pipe P, the ultrasonic waves transmitted from ultrasonic element 15A must be received by ultrasonic element 15B. Also, the ultrasonic waves transmitted from ultrasonic element 15B must be received by ultrasonic element 15A.

[0127] While the above-described element abnormality detection, mounting abnormality detection, non-filling abnormality detection, and bubble abnormality detection can determine an abnormality in the measurement state for each of the two ultrasonic elements 15, it cannot determine whether there is an abnormality in the transmission and reception of ultrasonic waves between the two ultrasonic elements 15.

[0128] Therefore, before or after the element abnormality detection, mounting abnormality detection, non-filling abnormality detection, and air bubble abnormality detection (in this example, after the four abnormality detections), it is determined whether there is an abnormality in the transmission and reception of ultrasound between the two ultrasonic elements 15. During this determination, for example, one ultrasonic element 15A operates in transmission mode and the other ultrasonic element 15B operates in reception mode. Based on the waveform obtained from the output signal of ultrasonic element 15B, it is determined whether or not it is receiving ultrasound transmitted from ultrasonic element 15A. If ultrasonic element 15B is receiving ultrasound from ultrasonic element 15A, it is determined whether or not the signal strength of the received ultrasound is above a predetermined fifth threshold.

[0129] If ultrasonic element 15B receives ultrasound from ultrasonic element 15A and the signal strength of that ultrasound is equal to or greater than the fifth threshold, the transmission of ultrasound from ultrasonic element 15A to ultrasonic element 15B is determined to be normal. If ultrasonic element 15B does not receive ultrasound transmitted from ultrasonic element 15A, the transmission of ultrasound from ultrasonic element 15A to ultrasonic element 15B is determined to be abnormal. Also, if the signal strength of the ultrasound received by ultrasonic element 15B from ultrasonic element 15A is less than the fifth threshold, the transmission of ultrasound from ultrasonic element 15A to ultrasonic element 15B is determined to be abnormal. This determination operation is also performed when the transmission and reception relationship is reversed. That is, one ultrasonic element 15A is operated in receiving mode and the other ultrasonic element 15B is operated in transmitting mode. Then, it is determined whether or not ultrasound was properly transmitted from ultrasonic element 15B to ultrasonic element 15A.

[0130] The fifth threshold value is a parameter predetermined according to the specifications of the ultrasonic element 15, and is stored in the storage unit 331 of the control unit 133 at the time of factory shipment of the ultrasonic flow sensor 100. The fifth threshold value stored in the storage unit 331 of the control unit 133 may also be changed by the user's operation of the operation unit 35.

[0131] (6) Disabling the abnormality diagnosis function As described above, the ultrasonic propagation paths required for element abnormality detection, mounting abnormality detection, non-filling abnormality detection, bubble abnormality detection, and transmission / reception abnormality detection increase in this order. Therefore, if an abnormality in the measurement state is detected in any of the above multiple detections, it is highly likely that subsequent abnormality detections will not be performed properly. Accordingly, in the abnormality diagnosis function according to this embodiment, if an abnormality is detected in any one of the multiple abnormality detections, only the completed detection result is presented to the user, and the abnormality diagnosis is terminated. In this way, if an abnormality is detected, subsequent abnormality detections that should be performed after that abnormality detection are not performed. As a result, the detection results for the diagnostic items for which a detection has been performed have a certain degree of reliability.

[0132] [5] Example of screen display in the display section 36 of the display unit 30 The user can, for example, instruct the ultrasonic flow sensor 100 to use the abnormality diagnosis function by operating the control unit 35 while referring to the screen displayed on the display unit 36 ​​in Figure 1. Figures 13 to 22 show examples of screen transitions displayed on the display unit 36 ​​in Figure 1 when the abnormality diagnosis function is used.

[0133] Figure 13 shows the initial screen. As shown in Figure 13, the display unit 36 ​​has a main display area 361 and a sub-display area 362. In the initial screen, the main display area 361 displays several (four in this example) function icons 361a indicating the various functions of the ultrasonic flow sensor 100. These function icons 361a include function icons 361a that combine a checkbox and the string "Status". These function icons 361a are used to check the flow measurement status by the ultrasonic flow sensor 100. The sub-display area 362 schematically displays the buttons of the operation unit 35 in Figure 1 (confirm button 35a and selection buttons 35b to 35e) that the user should operate.

[0134] The user can move the cursor on the main display area 361 and select the desired function icon 361a by operating the control unit 35 while referring to the sub-display area 362. In the example in Figure 13, the cursor is indicated by a dotted-dot frame.

[0135] In the initial screen shown in Figure 13, the function icon 361a for checking the flow rate measurement status by the ultrasonic flow sensor 100 is selected, and this selection is confirmed. In this case, as shown in Figure 14, the diagnostic execution icon 361b and the detailed display icon 361c are displayed in the main display area 361.

[0136] The diagnostic execution icon 361b is used to specify the execution of the abnormality diagnosis function for the measurement state, that is, the execution of the abnormality diagnosis process described later. On the other hand, the detailed display icon 361c is used to display various information, such as the settings of various parameters related to the measurement state, and various information regarding malfunctions of the ultrasonic flow sensor 100, such as response delay. The user can move the cursor on the main display area 361 and select either the diagnostic execution icon 361b or the detailed display icon 361c. In the example in Figure 14, the cursor is indicated by a dotted line frame, similar to the example in Figure 13.

[0137] In the screen shown in Figure 14, the diagnostic execution icon 361b is selected, and the selection is confirmed. In this case, as shown in Figure 15, a confirmation window 363 is displayed on the display unit 36. The confirmation window 363 displays a message (a message to confirm the transition from measurement mode to diagnostic mode, which will be described later) indicating that it will be temporarily impossible to measure the flow rate of the fluid FL in the piping P while the abnormality diagnosis process is being executed. In addition, the buttons on the operation unit 35 in Figure 1 that the user should operate (confirm button 35a and selection buttons 35b to 35e) are schematically displayed.

[0138] The user can command the execution of the abnormality diagnosis process by operating the confirmation button 35a (Figure 1) on the operation unit 35 while viewing the confirmation window 363. On the other hand, the user can return the display state of the display unit 36 ​​to the display state shown in Figure 14 by operating the selection button 35d on the operation unit 35.

[0139] In the screen shown in Figure 15, the abnormality diagnosis process is started when the confirmation button 35a (Figure 1) on the operation unit 35 is operated. In this case, as shown in Figure 16, a message indicating that the diagnosis has started is displayed in the main display area 361, along with a schematic diagram of the progress meter 361d and the sensor head 10. The progress meter 361d includes multiple light-emitting units arranged in a straight line in one direction within the main display area 361. In the progress meter 361d, as the abnormality diagnosis process progresses, the multiple light-emitting units light up sequentially, for example, from left to right. This displays the degree of progress of the abnormality diagnosis process.

[0140] When the abnormality diagnosis process is initiated, first, an abnormality check is performed on each of the ultrasonic elements 15A and 15B. At this time, as shown in Figure 17, the main display area 361 of the display unit 36 ​​displays a schematic diagram of the sensor head 10 showing the state in which an abnormality check is being performed, along with a message indicating that an abnormality check is currently being performed. In addition, a string indicating the ultrasonic element currently being checked (ultrasonic element 15A in the example of Figure 17) is displayed, and the display mode of the progress meter 361d is updated.

[0141] Next, once the element abnormality check is completed for each of the ultrasonic elements 15A and 15B, an installation abnormality check is performed. At this time, as shown in Figure 18, the main display area 361 of the display unit 36 ​​displays a schematic diagram of the sensor head 10 showing the state in which an installation abnormality check is being performed, along with a message indicating that an installation abnormality check is currently being performed. In addition, a string indicating the ultrasonic element currently being checked (ultrasonic element 15A in the example of Figure 18) is displayed, and the display mode of the progress meter 361d is updated.

[0142] Next, once the installation abnormality check is completed for each of the ultrasonic elements 15A and 15B, a non-charge abnormality check is performed. At this time, as shown in Figure 19, the main display area 361 of the display unit 36 ​​displays a schematic diagram of the sensor head 10 showing the state in which a non-charge abnormality check is being performed, along with a message indicating that a non-charge abnormality check is currently being performed. In addition, a string indicating the ultrasonic element currently being checked (ultrasonic element 15A in the example of Figure 19) is displayed, and the display mode of the progress meter 361d is updated.

[0143] Next, once the non-filling abnormality determination is completed for each of the ultrasonic elements 15A and 15B, the bubble abnormality determination is performed. At this time, as shown in Figure 20, the main display area 361 of the display unit 36 ​​displays a schematic diagram of the sensor head 10 showing the state in which the bubble abnormality determination is being performed, along with a message indicating that the bubble abnormality determination is currently being performed. In addition, a string indicating the ultrasonic element currently being determined (ultrasonic element 15A in the example of Figure 20) is displayed, and the display mode of the progress meter 361d is updated.

[0144] Next, once the bubble abnormality detection is complete for each of the ultrasonic elements 15A and 15B, a transmission / reception abnormality detection is performed. At this time, as shown in Figure 21, the main display area 361 of the display unit 36 ​​displays a schematic diagram of the sensor head 10 showing the state in which the transmission / reception abnormality detection is being performed, along with a message indicating that the transmission / reception abnormality detection is currently being performed. In addition, a string of characters showing how ultrasound is being transmitted and received between the two ultrasonic elements in the current transmission / reception abnormality detection is displayed, and the display mode of the progress meter 361d is updated. In the example in Figure 21, it is shown that ultrasound is transmitted and received in such a way that ultrasound transmitted from ultrasonic element 15A is received by ultrasonic element 15B.

[0145] Finally, once the series of abnormality checks described above for each of the ultrasonic elements 15A and 15B are completed, the main display area 361 of the display unit 36 ​​displays the check result list 361e and the message frame 361f, as shown in Figure 22.

[0146] In the judgment result list 361e shown in Figure 22, each of the strings for element abnormality, installation abnormality, non-charge abnormality, bubble abnormality, and transmission / reception abnormality is preceded by one of several types of marks indicating the judgment result. Specifically, for items where the judgment result was "no abnormality," a check mark is placed to indicate that it is normal (element abnormality). On the other hand, for items where the judgment result was "abnormality," a warning mark is placed to indicate that it is abnormal (installation abnormality). On the other hand, for items where no abnormality judgment was performed, a hyphen is placed to indicate that no abnormality judgment was performed. Messages corresponding to multiple judgment results are displayed in the message frame 361f. In the example in Figure 22, the content of the recovery work corresponding to the occurrence of an installation abnormality is shown.

[0147] In the display configuration of the display unit 36 ​​shown in Figures 16 to 22 above, the sub-display area 362 displays a mark indicating the OK button 35a of the operation unit 35 and the word "Stop". This allows the user to operate the OK button 35a at any desired timing during and after the execution of the abnormality diagnosis process. If the OK button 35a is operated during the abnormality diagnosis process, the process is interrupted, and the ultrasonic flow sensor 100 returns to the state before the start of the abnormality diagnosis process.

[0148] In the following explanation, as shown in Figures 16 to 22, the screen that shows the current processing status during the anomaly diagnosis process will be referred to as the diagnosis progress screen.

[0149] [6] Functional configuration of the control unit 133 in the control board 13 Figure 23 is a block diagram illustrating the functional configuration of the control unit 133 in the control board 13 shown in Figure 3. As shown in Figure 23, the control unit 133 includes a storage unit 331 and also includes a flow rate calculation unit 310, a measurement and determination unit 320, a mode switching unit 332, and a display control unit 333 as functional units. These functional units are realized by the CPU of the control unit 133 executing a flow rate measurement program and an abnormality diagnosis program stored in the storage unit 331. Note that some or all of the above functional units may be realized by hardware such as electronic circuits.

[0150] The flow rate calculation unit 310 includes a first calculation unit 311 and a second calculation unit 312. The first calculation unit 311 propagates ultrasonic waves between two ultrasonic elements 15A and 15B by controlling a transmitting circuit 131 and a receiving circuit 132. As a result, the first calculation unit 311 calculates the flow rate of the fluid FL in the pipe P based on the difference in ultrasonic wave propagation time between the two ultrasonic elements 15A and 15B.

[0151] The second calculation unit 312 controls the transmission circuit 131 to cause one ultrasonic element (for example, ultrasonic element 15A) to transmit ultrasonic waves to the fluid FL in the pipe P. The second calculation unit 312 also receives a signal output to the receiving circuit 132 when one ultrasonic element receives ultrasonic waves from the fluid FL, and calculates the flow rate of the fluid FL in the pipe P based on the frequency shift of the ultrasonic waves.

[0152] The measurement and determination unit 320 includes an element determination unit 321, an installation determination unit 322, a filling determination unit 323, a bubble determination unit 324, and a transmission / reception determination unit 325. The element determination unit 321 controls the transmission circuit 131 and the reception circuit 132 and performs the above-mentioned element abnormality determination based on a first threshold value and a first range TA1 etc. stored in the storage unit 331.

[0153] The mounting determination unit 322 controls the transmitting circuit 131 and the receiving circuit 132 and performs the above-mentioned element abnormality determination based on the second threshold value and the second range TA2 etc. stored in the storage unit 331. The charging determination unit 323 controls the transmitting circuit 131 and the receiving circuit 132 and performs the above-mentioned non-charging abnormality determination based on the third threshold value and the third range TA3 etc. stored in the storage unit 331.

[0154] The bubble detection unit 324 controls the transmitting circuit 131 and the receiving circuit 132 and performs the above bubble abnormality determination based on the fourth threshold value and the fourth range TA4 etc. stored in the storage unit 331. The transmission / reception determination unit 325 controls the transmitting circuit 131 and the receiving circuit 132 and performs the above bubble abnormality determination based on the fifth threshold value etc. stored in the storage unit 331.

[0155] When the user operates the operation unit 35 and commands the execution of an abnormality diagnosis process, the mode switching unit 332 stops the flow rate measurement operation by the flow rate calculation unit 310 and starts the abnormality diagnosis operation by the measurement determination unit 320. Also, when the measurement determination unit 320 commands the end of the abnormality diagnosis, the mode switching unit 332 stops the abnormality diagnosis operation by the measurement determination unit 320 and starts the flow rate measurement operation by the flow rate calculation unit 310.

[0156] The display control unit 333 displays multiple types of judgment results from the measurement judgment unit 320 regarding the flow rate measurement status by the ultrasonic flow sensor 100 on the display unit 36 ​​of the display device 30. In addition, the display control unit 333 displays information related to various abnormality judgments performed by the measurement judgment unit 320 (such as a diagnostic progress screen) on the display unit 36.

[0157] [7] Anomaly diagnosis process Figures 24 and 25 are flowcharts illustrating the flow of the abnormality diagnosis process for realizing the abnormality diagnosis function. The abnormality diagnosis process in Figures 24 and 25 is performed by the CPU of the control unit 133 executing the abnormality diagnosis program stored in the memory unit 331, and is repeated at predetermined intervals when the ultrasonic flow sensor 100 is powered on. In the initial state, the ultrasonic flow sensor 100 is assumed to be in a normal operating state, that is, measuring the flow rate of the fluid FL in the piping P at predetermined intervals.

[0158] In the following description, the operating mode of the control unit 133 when the ultrasonic flow sensor 100 is in a normal operating state will be referred to as the measurement mode. In the measurement mode, the control unit 133 transmits ultrasonic waves from at least one of the two ultrasonic elements 15, and measures the flow rate of the fluid in the piping P based on the signal output when a predetermined ultrasonic element 15 receives the ultrasonic waves, in a predetermined order (sequence).

[0159] Furthermore, in the following description, the operating mode of the control unit 133 when the abnormality diagnosis function is used in the ultrasonic flow sensor 100 will be referred to as the diagnostic mode. In the measurement mode, the control unit 133 transmits ultrasound from at least one of the two ultrasonic elements 15, and performs a plurality of abnormality judgments in a predetermined order (sequence) based on the signal output when a predetermined ultrasonic element 15 receives ultrasound.

[0160] As shown in Figure 24, first, the mode switching unit 332 determines whether or not the execution of an abnormality diagnosis process has been commanded by the user operating the operation unit 35 (step S101). This command is given to the mode switching unit 332 when, for example, the diagnostic execution icon 361b in Figure 14 is selected and its selection is confirmed. If the execution of an abnormality diagnosis process is not commanded, the mode switching unit 332 repeats the process in step S101. On the other hand, if the execution of an abnormality diagnosis process is commanded, the display control unit 333 in Figure 23 displays a confirmation window 363 on the display unit 36 ​​of the display unit 30 to confirm the switch from measurement mode to diagnostic mode (step S102).

[0161] Subsequently, the mode switching unit 332 determines whether or not the execution of the abnormality diagnosis process has been re-commanded (step S103). This re-command is given to the mode switching unit 332, for example, when the confirmation button 35a (Figure 1) of the operation unit 35 is operated while the display state of Figure 15 is shown. If the execution of the abnormality diagnosis process is not re-commanded, the mode switching unit 332 repeats the process of step S101. On the other hand, if the execution of the abnormality diagnosis process is re-commanded, the mode switching unit 332 switches the operating mode of the control unit 133 from measurement mode to diagnosis mode (step S104). As a result, the behavior of the ultrasonic flow sensor 100, which measures the flow rate of fluid in the piping P, is switched to sequentially perform multiple abnormality judgments. The display control unit 333 also starts displaying a diagnosis progress screen that shows the current processing content during the abnormality diagnosis process (step S105).

[0162] Next, the element determination unit 321 of the measurement determination unit 320 performs an element abnormality determination for each of the two ultrasonic elements 15 (step S106) and determines whether there is an element abnormality (step S107). If an element abnormality is found in step S107, the display control unit 333 displays a result list screen showing all the determination results obtained so far on the display unit 36 ​​(step S120). After that, the display control unit 333 proceeds to the process in step S117, which will be described later.

[0163] If there is no element abnormality in step S107, the mounting determination unit 322 of the measurement determination unit 320 performs a mounting abnormality determination for each of the two ultrasonic elements 15 (step S108) and determines whether there is a mounting abnormality (step S109).

[0164] If there is an installation abnormality in step S109, the display control unit 333 proceeds to the process of step S120. If there is no installation abnormality in step S109, the filling determination unit 323 of the measurement determination unit 320 performs a non-filling abnormality determination for each of the two ultrasonic elements 15 (step S110) and determines whether there is a non-filling abnormality (step S111). If there is a non-filling abnormality in step S111, the display control unit 333 proceeds to the process of step S120.

[0165] If there is no non-filling abnormality in step S111, the bubble determination unit 324 of the measurement determination unit 320 performs a bubble abnormality determination for each of the two ultrasonic elements 15 (step S112) and determines whether there is a bubble abnormality (step S113). If there is a bubble abnormality in step S113, the display control unit 333 proceeds to the process of step S120.

[0166] If there is no bubble abnormality in step S113, the transmission / reception determination unit 325 of the measurement determination unit 320 performs a transmission / reception abnormality determination between the two ultrasonic elements 15 (step S114) and determines whether there is a transmission / reception abnormality (step S115). If there is a transmission / reception abnormality in step S115, the display control unit 333 proceeds to the process of step S120.

[0167] If there are no transmission or reception errors in step S115, the display control unit 333 displays a results list screen on the display unit 36 ​​indicating that all judgment results were normal (step S116). Subsequently, the display control unit 333 terminates the display of the results list for various abnormal judgments, for example, when it receives a command from the user to terminate the display of the results list (step S117). Finally, the mode switching unit 332 switches the operating mode of the control unit 133 from diagnostic mode to measurement mode (step S118). This completes the abnormal diagnosis process.

[0168] In addition, in the above abnormality diagnosis process, steps S114 and S115 may be performed between steps S103 to S106.

[0169] [8] Effects The ultrasonic flow sensor 100 described above operates in one of the following modes: propagation time difference mode, pulse Doppler mode, or hybrid mode, when the control unit 133 is in measurement mode and the sensor head 10 is attached to the pipe P. This allows the flow rate of the fluid in the pipe P to be measured.

[0170] The user can instruct the ultrasonic flow sensor 100 to use the abnormality diagnosis function by operating the control unit 35 of the display unit 30. In this case, the measurement mode sequence of the ultrasonic flow sensor 100 is interrupted, and the measurement of the fluid flow rate in the pipe P is stopped. When the diagnostic mode sequence is started, the ultrasonic element 15A first switches between transmission mode and reception mode alternately. As a result, ultrasonic waves are transmitted from the ultrasonic element 15A towards the pipe P, and ultrasonic waves reflected from the outside are received by the ultrasonic element 15A. Based on the output signal of the ultrasonic element 15A, element abnormality detection, installation abnormality detection, non-filling abnormality detection and bubble abnormality detection for the ultrasonic element 15A are performed according to a predetermined sequence.

[0171] Similar to ultrasonic element 15A, ultrasonic element 15B is also subjected to detection of element abnormalities, mounting abnormalities, non-filling abnormalities, and air bubble abnormalities. Furthermore, transmission and reception abnormalities are detected when ultrasonic waves are transmitted and received between ultrasonic elements 15A and 15B. Subsequently, the various detection results are displayed on the display unit 36 ​​of the display unit 30. This makes it easy for the user to understand any abnormalities in the flow rate measurement status by the ultrasonic flow sensor 100.

[0172] [9] Other embodiments (1) In the above embodiment, the sensor head 10 is configured to operate in any of the following flow rate calculation modes: propagation time difference mode, pulse Doppler mode, and hybrid mode, but the embodiment is not limited thereto. The sensor head 10 only needs to be configured to operate in pulse Doppler mode. Therefore, the sensor head 10 does not need to be configured to operate in propagation time difference mode or hybrid mode. In this case, the ultrasonic flow sensor 100 does not need to include either of the ultrasonic elements 15A or 15B. Note that if the ultrasonic flow sensor 100 does not include either of the ultrasonic elements 15A or 15B, the abnormality diagnosis function does not include transmission / reception abnormality determination.

[0173] (2) In the above embodiment, various abnormality determinations of the abnormality diagnosis function are performed in response to commands made by the user operating the operation unit 35, but the embodiment is not limited thereto. Various abnormality determinations of the abnormality diagnosis function may be performed automatically by the control unit 133 at predetermined timings.

[0174] (3) In the above embodiment, the ultrasonic elements 15A and 15B are provided as part of the ultrasonic flow sensor 100, but the embodiment is not limited thereto. The two ultrasonic elements 15A and 15B may be provided separately from each other, as long as ultrasonic waves can be transmitted and received between the two ultrasonic elements 15A and 15B through the fluid flowing in the piping P.

[0175] (4) In the above embodiment, the ultrasonic element 15A and the ultrasonic element 15B are arranged to be aligned along the direction in which the pipe P extends, but the embodiment is not limited thereto. The ultrasonic element 15A and the ultrasonic element 15B may be arranged to face each other across the pipe P.

[0176] (5) In the abnormality diagnosis process according to the above embodiment, element abnormality determination, mounting abnormality determination, non-filling abnormality determination, bubble abnormality determination, and transmission / reception abnormality determination are performed in this order, but some of these multiple abnormality determinations may be omitted. For example, in the abnormality diagnosis process, element abnormality determination, mounting abnormality determination, bubble abnormality determination, and transmission / reception abnormality determination are performed in this order, and non-filling abnormality determination may be omitted.

[0177]

[10] Correspondence between each component of the claim and each part of the embodiment The following describes examples of the correspondence between each component of the claims and each part of the embodiments, but the present invention is not limited to the following examples. Various other elements having the configuration or function described in the claims can also be used as each component of the claims.

[0178] In the above embodiment, piping P is an example of piping, fluid FL is an example of fluid, ultrasonic flow sensor 100 is an example of a clamp-on type ultrasonic flow sensor, ultrasonic elements 15, 15A are an example of a first ultrasonic element and ultrasonic elements, ultrasonic elements 15, 15B are an example of a second ultrasonic element, control unit 133 is an example of a control unit, flow rate calculation unit 310 is an example of a flow rate calculation unit, measurement and determination unit 320 is an example of a measurement and determination unit, mode switching unit 332 is an example of a mode switching unit, first calculation unit 311 is an example of a first calculation unit, and second calculation unit 312 is an example of a second calculation unit.

[0179] Furthermore, the wedge material 14 and the acoustic couplant 16 are examples of transmission members, the first range TA1 is an example of the first range, the element determination unit 321 is an example of the element determination unit, the second range TA2 is an example of the second range, the mounting determination unit 322 is an example of the mounting determination unit, the third range TA3 is an example of the third range, the filling determination unit 323 is an example of the filling determination unit, the fourth range TA4 is an example of the fourth range, the bubble determination unit 324 is an example of the bubble determination unit, the transmission / reception determination unit 325 is an example of the transmission / reception determination unit, and the display unit 36 ​​is an example of the display unit. [Explanation of Symbols]

[0180] 10...Sensor head, 11, 31...Housing, 12, 32...Connector, 13...Control board, 14, 14A, 14B...Wedge material, 14a...Element coupling surface, 14b...Pipe coupling surface, 15, 15A, 15B...Ultrasonic element, 16...Acoustic couplant, 17...Ultrasonic shielding plate, 18...Indicator light, 20...Clamp part, 21...Upper clamp member, 22...Lower clamp member, 23...Clamp fixing screw, 30...Display unit, 33, 133...Control unit, 34...Memory element, 35...Operation unit, 35a...Confirm button, 35b, 35c, 35d, 35e...Selection button, 36...Display unit, 37...Indicator light, 38, 39...Connection port, 40...Power supply circuit, 100...Ultrasonic flow sensor, 101...Fixing screw, 131...Transmission circuit, 13 2...Receiving circuit, 310...Flow rate calculation unit, 311...First calculation unit, 312...Second calculation unit, 320...Measurement and determination unit, 321...Element determination unit, 322...Installation determination unit, 323...Filling determination unit, 324...Bubble determination unit, 325...Transmission and reception determination unit, 331...Memory unit, 332...Mode switching unit, 333...Display control unit, 361...Main display area, 361a...Function icon, 361b...Diagnosis execution icon, 361c...Detailed display icon, 361d...Progress meter, 361e...Determination result list, 361f...Message frame, 362...Sub display area, 363...Confirmation window, AR...Air, FL...Fluid, P...Piping, TA1...First range, TA2...Second range, TA3...Third range, TA4...Fourth range

Claims

1. A clamp-on ultrasonic flow sensor for measuring the flow rate of fluid flowing through a pipe, A first ultrasonic element is attached to a portion of the outer surface of the aforementioned pipe, capable of transmitting ultrasonic waves toward the pipe and receiving ultrasonic waves, and outputting a signal indicating the intensity of the ultrasonic waves received when ultrasonic waves are received. A second ultrasonic element is attached to another part of the outer surface of the aforementioned pipe, and is capable of transmitting ultrasonic waves toward the pipe and receiving ultrasonic waves, and outputs a signal indicating the intensity of the ultrasonic waves received when ultrasonic waves are received. The system includes a control unit configured to operate in a measurement mode for measuring the flow rate of the fluid and a diagnostic mode for diagnosing the state related to the measurement of the fluid flow rate. The control unit, A flow rate calculation unit that calculates the flow rate of the fluid by controlling the first and second ultrasonic elements in the measurement mode, The diagnostic mode includes a measurement determination unit that controls the first ultrasonic element to transmit ultrasonic waves from the first ultrasonic element and determines the measurement state of the fluid flow rate in a sequence different from the measurement mode, based on the signal output from the ultrasonic element among the first and second ultrasonic elements that is to receive the ultrasonic waves transmitted from the first ultrasonic element. The measurement and determination unit makes at least one of the following determinations to determine the measurement state of the fluid flow rate: whether the first ultrasonic element is abnormal, and whether the mounting state of the first ultrasonic element is abnormal. The measurement state of the fluid flow rate includes multiple measurement states corresponding to multiple diagnostic items, The clamp-on ultrasonic flow sensor further includes a display unit that displays the plurality of diagnostic items side by side and displays the determination result of each measurement state determined by the measurement determination unit in correspondence with the diagnostic item of that measurement state.

2. The clamp-on ultrasonic flow sensor according to claim 1, wherein the control unit, while in the diagnostic mode, performs determination of the plurality of measurement states in the order of the plurality of diagnostic items predetermined as a sequence of the diagnostic mode.

3. The aforementioned plurality of diagnostic items include a first diagnostic item for determining whether the first ultrasonic element is abnormal, a second diagnostic item for determining whether the mounting state of the first ultrasonic element is abnormal, a third diagnostic item for determining whether the inside of the piping is filled with the fluid, and a fourth diagnostic item for determining whether there are bubbles in the fluid inside the piping that exceed a predetermined amount. The clamp-on ultrasonic sensor according to claim 2, wherein the control unit, while in the diagnostic mode, determines the measurement state corresponding to the first and second diagnostic items as part of the diagnostic mode sequence, and then determines the measurement state corresponding to the third and fourth diagnostic items.

4. The clamp-on ultrasonic flow sensor according to any one of claims 1 to 3, further comprising a mode switching unit that receives input for an operating mode to be switched to in the control unit and switches the operating mode of the control unit to the received operating mode.

5. The flow rate calculation unit is, A clamp-on ultrasonic flow sensor according to any one of claims 1 to 4, comprising a first calculation unit that calculates the flow rate of the fluid based on the difference in ultrasonic wave propagation time between the first ultrasonic element and the second ultrasonic element.

6. The flow rate calculation unit is, A clamp-on ultrasonic flow sensor according to any one of claims 1 to 5, comprising: a second calculation unit that calculates the flow rate of the fluid based on the frequency shift of the ultrasonic waves received by the first ultrasonic element when the first ultrasonic element transmits ultrasonic waves.

7. The ultrasonic element to receive ultrasonic waves transmitted from the first ultrasonic element includes the first ultrasonic element, A transmission member for transmitting ultrasonic waves is provided between the first ultrasonic element and the piping. The clamp-on ultrasonic flow sensor according to claim 1, wherein the measurement determination unit includes an element determination unit that determines whether the first ultrasonic element is abnormal as a measurement state, based on whether the ultrasonic intensity in the ultrasonic waveform, which shows a change in the ultrasonic intensity indicated by the signal output from the first ultrasonic element, satisfies a predetermined first condition in a first range of the time axis corresponding to a first portion of the ultrasonic path within the transmission member.

8. The ultrasonic element to receive ultrasonic waves transmitted from the first ultrasonic element includes the first ultrasonic element, The clamp-on ultrasonic flow sensor according to claim 1 or 7, wherein the measurement determination unit includes an installation determination unit that determines whether the installation state of the first ultrasonic element is abnormal as a measurement state, based on whether the ultrasonic intensity satisfies a predetermined second condition in a second range of the time axis corresponding to a second portion of the ultrasonic path including the outer surface of the piping, in an ultrasonic waveform showing a change in the ultrasonic intensity indicated by the signal output from the first ultrasonic element.

9. The ultrasonic element to receive ultrasonic waves transmitted from the first ultrasonic element includes the first ultrasonic element, The clamp-on ultrasonic flow sensor according to any one of claims 1, 7, or 8, wherein the measurement determination unit includes a filling determination unit that determines whether the inside of the pipe is filled with the fluid as the measurement state, based on whether the ultrasonic intensity satisfies a predetermined third condition in a third range of the time axis corresponding to a third portion of the ultrasonic path including the inner surface of the pipe, in an ultrasonic waveform showing a change in the ultrasonic intensity indicated by the signal output from the first ultrasonic element.

10. The ultrasonic element to receive ultrasonic waves transmitted from the first ultrasonic element includes the first ultrasonic element, The clamp-on ultrasonic flow sensor according to any one of claims 1 or 7 to 9, wherein the measurement determination unit includes a bubble determination unit that determines whether or not a predetermined amount or more of bubbles exist in the fluid in the pipe as the measurement state, based on whether or not the ultrasonic intensity satisfies a predetermined fourth condition in a fourth range of the time axis corresponding to a fourth portion of the ultrasonic path inside the pipe in the ultrasonic waveform showing a change in the ultrasonic intensity indicated by the signal output from the first ultrasonic element.

11. The ultrasonic element to receive ultrasonic waves transmitted from the first ultrasonic element includes the second ultrasonic element, The clamp-on ultrasonic flow sensor according to any one of claims 1 or 7 to 10, wherein the measurement determination unit includes a transmission / reception determination unit that determines the ultrasonic transmission state between the first ultrasonic element and the second ultrasonic element as the measurement state based on a signal output from the second ultrasonic element.

12. A clamp-on ultrasonic flow sensor for measuring the flow rate of a fluid flowing in a pipe, An ultrasonic element is attached to a portion of the outer surface of the aforementioned pipe, capable of transmitting ultrasonic waves toward the pipe and receiving ultrasonic waves, and outputting a signal indicating the intensity of the received ultrasonic waves when ultrasonic waves are received. The system includes a control unit configured to operate in a measurement mode for measuring the flow rate of the fluid and a diagnostic mode for diagnosing the state related to the measurement of the fluid flow rate. The control unit, A flow rate calculation unit that calculates the flow rate of the fluid by controlling the ultrasonic element in the measurement mode, The diagnostic mode includes a measurement and determination unit that controls the ultrasonic element to transmit ultrasonic waves from the ultrasonic element and determines the measurement state of the fluid flow rate based on the signal output from the ultrasonic element, The measurement and determination unit makes at least one of the following determinations to determine the measurement state of the fluid flow rate: whether the ultrasonic element is abnormal or whether the mounting state of the ultrasonic element is abnormal. The measurement state of the fluid flow rate includes multiple measurement states corresponding to multiple diagnostic items, The clamp-on ultrasonic flow sensor further includes a display unit that displays the plurality of diagnostic items side by side and displays the determination result of each measurement state determined by the measurement determination unit in correspondence with the diagnostic item of that measurement state.

13. The control unit, while in the diagnostic mode, performs a determination of at least one of the plurality of measurement states in the order of the plurality of diagnostic items predetermined as the sequence of the diagnostic mode. The aforementioned display unit is During the operation of the control unit based on the sequence, For each measurement state in which a determination has been made among the multiple measurement states, the determination result by the measurement determination unit is displayed so that the diagnostic item corresponding to that measurement state can be identified. The clamp-on ultrasonic flow sensor according to claim 1 or 12, wherein, for each of the multiple measurement states for which a determination has not been performed, the measurement determination unit displays that a determination was not performed, so as to identify the diagnostic item corresponding to that measurement state.

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