Flow Rate Detector

Abstract

To improve the detection accuracy of a flow rate in a drain trap.SOLUTION: A flow rate detection device 10 comprises: a probe 18 that detects vibrations of a steam trap 2 and outputs a vibration signal; a transmission part 151 that transmits a reference signal; a modulation part 152 that frequency-modulates the vibration signal outputted from the probe 18 with respect to the reference signal transmitted from the transmission part 151; a filter part 154 that extracts components in a predetermined frequency band in the vibration signal frequency-modulated by the modulation part 152; and a derivation part 16 that derives a steam leaking flow rate from vibrations according to the vibration signal extracted by the filter part 154, on the basis of a correlation relationship between vibrations of the steam trap 2 and the steam leaking flow rate which is prepared in advance. The transmission part 151 sweeps the frequency of the reference signal within a predetermined range with lapse of time.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology of the present disclosure relates to a flow rate detection device. [Background technology]

[0002] Conventionally, devices for detecting the drain flow rate of drain traps, etc. For example, the detection device disclosed in Patent Document 1 includes a vibration sensor that detects the vibration of a valve, and a derivation unit that calculates the drain flow rate from the vibration detected by the vibration sensor based on a pre-stored correlation between the drain flow rate and the vibration. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-196716 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the device of Patent Document 1, there is variation in the vibration value detected by the vibration sensor, which may result in a decrease in the detection accuracy of the drain flow rate.

[0005] The technology of the present disclosure has been made in consideration of the above circumstances, and its purpose is to provide a flow rate detection device that can improve the detection accuracy of the flow rate in a drain trap. [Means for solving the problem]

[0006] The technology disclosed herein includes a detection unit, a transmission unit, a modulation unit, a filter unit, and a derivation unit. The detection unit detects vibration of a drain trap and outputs a vibration signal of the vibration. The transmission unit transmits a reference signal. The modulation unit frequency-modulates the vibration signal output from the detection unit with respect to the reference signal transmitted from the transmission unit. The filter unit extracts components of a predetermined frequency band from the vibration signal frequency-modulated by the modulation unit. The derivation unit derives the flow rate from the vibration corresponding to the vibration signal extracted by the filter unit, based on a correlation between the vibration of the drain trap and the flow rate that has been prepared in advance. The transmission unit then sweeps the frequency of the reference signal within a predetermined range over time. [Effects of the Invention]

[0007] According to the flow rate detection device, it is possible to improve the accuracy of detecting the flow rate in the drain trap. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a flow rate detection device. [Figure 2] FIG. 2 is a block diagram showing the configuration of the signal processing unit. [Figure 3] FIG. 3 is a flowchart showing the detection operation of the flow rate detection device. [Figure 4] FIG. 4 is a diagram for explaining the operation of the modulation section. [Figure 5] FIG. 5 is a diagram showing a vibration signal after frequency modulation by a modulation section. [Figure 6] FIG. 6 is a diagram showing a vibration signal after frequency modulation by a conventional modulation section. [Figure 7] FIG. 7 is a diagram for explaining the operation of the filter section. [Figure 8] FIG. 8 is a diagram showing the vibration signal after extraction by the filter unit. [Figure 9] FIG. 9 is a diagram showing a vibration signal after extraction by a conventional filter unit. [Figure 10] FIG. 10 is a diagram in which the vibration level after conversion by the AD conversion unit is plotted for each measurement. DETAILED DESCRIPTION OF THE INVENTION

[0009] Exemplary embodiments will now be described in detail with reference to the accompanying drawings.

[0010] FIG. 1 is a schematic diagram showing the configuration of a flow rate detecting device 10. The flow rate detecting device 10 of this embodiment detects the steam leakage flow rate in a steam trap 2 provided in, for example, a steam system, i.e., the leakage flow rate of steam leaking downstream from the steam trap 2. The steam leakage flow rate is an example of a flow rate. The steam trap 2 is an example of a drain trap, and is provided, for example, in a drain pipe 1. The steam trap 2 is a so-called automatic valve that allows drain to flow downstream when drain flows in from the drain pipe 1, but prevents the outflow of steam when steam flows in from the drain pipe 1.

[0011] As shown in FIG. 1, the flow rate detecting device 10 includes a device body 11 and a probe 18.

[0012] The probe 18 is an example of a detection unit that detects vibrations (e.g., vibration level) of the steam trap 2. The probe 18 detects vibrations of the steam trap 2, for example, by being pressed against the casing of the steam trap 2. The probe 18 outputs a vibration signal of the detected vibrations. For example, the probe 18 has a piezoelectric element (not shown). When the probe 18 is pressed against the casing of the steam trap 2, the mechanical vibrations of the steam trap 2 act on the piezoelectric element as pressure fluctuations. This causes a voltage fluctuation in the piezoelectric element, and a vibration signal related to this voltage fluctuation is output.

[0013] The probe 18 is connected to the device main body 11 via a cable 18a. The probe 18 outputs a vibration signal related to the steam trap 2 to the device main body 11 via the cable 18a. More specifically, the probe 18 amplifies and outputs the component at or near the resonant frequency of the probe 18 in the vibration signal of the detected vibration.

[0014] The device main body 11 and the probe 18 may be integrally formed. Alternatively, the device main body 11 and the probe 18 may be wirelessly connected by a wireless communication standard such as Bluetooth (registered trademark).

[0015] The device main body 11 derives the steam leakage flow rate in the steam trap 2 based on the vibration signal output from the probe 18. Specifically, the device main body 11 has an input unit 12, a memory unit 13, a display unit 14, a signal processing unit 15, and a derivation unit 16.

[0016] The input unit 12 receives an input operation from a user (e.g., an operator). The input unit 12 outputs an input signal corresponding to the input operation by the user. The input unit 12 is, for example, an input key or a touch panel that is overlaid on the display unit 14 described later.

[0017] The storage unit 13 is a computer-readable storage medium that stores various programs and various data. The storage unit 13 is formed by a magnetic disk such as a hard disk, an optical disk such as a CD-ROM or DVD, or a semiconductor memory. Specifically, the storage unit 13 pre-stores the correlation between the vibration (vibration level) of the steam trap 2 and the steam leakage flow rate (hereinafter also referred to as correlation data). More specifically, the storage unit 13 stores the correlation data for each model of the steam trap 2.

[0018] Display unit 14 displays, for example, the steam leakage flow rate derived by derivation unit 16. Display unit 14 may also display, in addition to the steam leakage flow rate, the vibration level output from signal processing unit 15 to derivation unit 16. Display unit 14 is, for example, a liquid crystal display or an organic EL display.

[0019] The signal processing unit 15 performs predetermined processing on the vibration signal output from the probe 18 to the device main body 11. The signal processing unit 15 outputs a vibration level corresponding to the vibration signal that has been subjected to the predetermined processing to the derivation unit 16. The specific configuration of the signal processing unit 15 will be described later.

[0020] The derivation unit 16 derives the steam leakage flow rate from the vibration corresponding to the vibration signal extracted by the filter unit 155 (described later) based on a correlation between the vibration of the steam trap 2 and the steam leakage flow rate prepared in advance. In other words, the derivation unit 16 reads the correlation from the storage unit 13, and derives the steam leakage flow rate from the vibration level output from the signal processing unit 15 based on the correlation. The derivation unit 16 is realized by, for example, a microcomputer or a processor and various semiconductor memories.

[0021] 2 is a block diagram showing the configuration of signal processing unit 15. Signal processing unit 15 has transmitting unit 151, modulating unit 152, amplifying unit 153, filtering unit 154, and AD converting unit 155.

[0022] The transmitter 151 transmits a reference signal. That is, the transmitter 151 outputs the reference signal to the modulator 152. The transmitter 151 then sweeps the frequency of the reference signal within a predetermined range (hereinafter also referred to as a predetermined variation range) over time. More specifically, the transmitter 151 varies the frequency of the reference signal by making it go back and forth within the predetermined range once or multiple times within a predetermined measurement time. The predetermined measurement time is the measurement time (i.e., detection time) of one vibration by the probe 18. That is, the probe 18 continues to be pressed against the steam trap 2 for the predetermined measurement time. The predetermined measurement time is, for example, 15 seconds.

[0023] More specifically, the predetermined fluctuation range is a range that includes the variation width of the frequency of the vibration signal output from the probe 18. The variation width is the error in the frequency of the vibration signal for each detection (each measurement) by the probe 18. In other words, all frequencies of the vibration signal output from the probe 18 are within the predetermined fluctuation range.

[0024] The modulation unit 152 frequency-modulates the vibration signal output from the probe 18 with respect to the reference signal transmitted from the transmission unit 151. The modulation unit 152 outputs the frequency-modulated vibration signal to the amplification unit 153. The amplification unit 153 amplifies the vibration signal output from the modulation unit 152 and outputs it to the filter unit 154. The filter unit 154 extracts components of a predetermined frequency band from the vibration signal frequency-modulated by the modulation unit 152. That is, the filter unit 154 extracts components of a predetermined frequency band from the vibration signal output from the amplification unit 153. The AD conversion unit 155 converts the vibration signal extracted by the filter unit 154 into a vibration level by AD conversion. The vibration level converted by the AD conversion unit 155 is input to the derivation unit 16.

[0025] Next, the operation of detecting a steam leakage flow rate by the flow rate detecting device 10 configured as above will be described with reference to Fig. 3. Fig. 3 is a flowchart showing the detection operation by the flow rate detecting device 10.

[0026] First, prior to step S1, the user inputs the type of steam trap 2 to be detected using input unit 12. Next, the user presses probe 18 against the steam trap 2 to be detected, thereby detecting vibrations of the steam trap 2 (step S1). Specifically, one vibration measurement (detection) is performed by keeping probe 18 pressed against steam trap 2 for a predetermined measurement time (e.g., 15 seconds).

[0027] In the next step S2, the probe 18 amplifies the vibration signal of the detected vibration. Specifically, the probe 18 amplifies the components of the vibration signal at or near the resonant frequency of the probe 18. This enhances the vibration signal. In this example, the resonant frequency is 42 kHz. The vibration signal thus amplified by the probe 18 is output to the modulation unit 152 of the device main body 11.

[0028] Fig. 4 is a diagram for explaining the operation of modulation section 152. Fig. 5 is a diagram showing vibration signals A1 to A3 after frequency modulation by modulation section 152. Fig. 6 is a diagram showing vibration signals A1 to A3 after frequency modulation by a conventional modulation section.

[0029] In the following step S3, the modulation unit 152 frequency-modulates the vibration signal output from the probe 18. Specifically, the modulation unit 152 frequency-modulates the vibration signal output from the probe 18 relative to the reference signal transmitted from the transmission unit 151. For ease of explanation, as shown in FIG. 4, three vibration signals A1 to A3 (i.e., vibration signals obtained by three measurements) that vary from one another are collectively shown. In this example, the modulation unit 152 modulates the vibration signals A1 to A3 to a frequency of 2 kHz, which is in the audible range. In other words, the modulation unit 152 shifts the vibration of the steam trap 2, which is in the ultrasonic range, into the audible range. In this example, the reference frequency of the reference signal B transmitted from the transmission unit 151 is set to 40 kHz. The frequency of the reference signal B then sweeps over time within a predetermined fluctuation range X. Furthermore, in this example, the fluctuation range X is set to 40 KHz (i.e., the reference frequency) to 45 KHz, taking into consideration the variation width Y of the frequencies of the three vibration signals A1 to A3 and the pass band of the filter unit 154. The variation width Y is a range that includes the resonance frequency (42 KHz).

[0030] In this way, in modulation section 152, vibration signals A1 to A3 are frequency-modulated while the frequency of reference signal B is swept within predetermined fluctuation range X. Therefore, as shown in Fig. 5, the amplitude of each of the three vibration signals A1 to A3 is substantially averaged in a certain frequency band. In other words, the amplitude of each is substantially averaged in a certain frequency band within frequency range R corresponding to fluctuation range X. Moreover, since fluctuation range X is a range that takes into account variation width Y and the pass band of filter section 154, the amplitude is averaged corresponding to the entire pass band of filter section 154.

[0031] If the vibration signals A1 to A3 were frequency modulated without sweeping the frequency of reference signal B as in the conventional method, i.e., while maintaining the frequency of reference signal B at the reference frequency, the amplitudes of none of the three vibration signals A1 to A3 would be averaged, as shown in Figure 6.

[0032] The vibration signals A1 to A3 frequency-modulated by the modulation unit 152 are output to the amplification unit 153. The amplification unit 153 amplifies the vibration signals A1 to A3 output from the modulation unit 152 (step S4). This enhances the vibration signals A1 to A3, the amplitudes of which have been substantially averaged. The vibration signals A1 to A3 amplified by the amplification unit 153 are output to the filter unit 154.

[0033] Fig. 7 is a diagram for explaining the operation of filter section 154. Fig. 8 is a diagram showing vibration signals A1 to A3 after extraction by filter section 154. Fig. 9 is a diagram showing vibration signals A1 to A3 after extraction by a conventional filter section.

[0034] In the following step S5, filter unit 154 extracts components of a predetermined frequency band Z from vibration signals A1 to A3 output from amplifier unit 153. That is, in filter unit 154, the components of the predetermined frequency band Z are extracted by a band-pass filter having the predetermined frequency band Z as its passband, as shown in Fig. 7, for example. The three vibration signals A1 to A3 processed in this way by filter unit 154 are extracted as signals with little variation from one another, as shown in Fig. 8, for example. That is, by extracting the components of frequency band Z in which the amplitudes of the three vibration signals A1 to A3 are substantially averaged, three vibration signals A1 to A3 with little variation from one another are obtained.

[0035] If vibration signals A1 to A3 that have been frequency modulated without sweeping the frequency of reference signal B are processed by filter section 154 as in the conventional method, they will be extracted as three vibration signals A1 to A3 that vary greatly from one another, as shown in Figure 9, for example.

[0036] In the following step S6, the AD conversion unit 155 performs AD conversion on the vibration signals A1 to A3 extracted by the filter unit 154 to derive vibration levels. FIG. 10 is a diagram in which the vibration levels after conversion by the AD conversion unit 155 are plotted for each measurement. Note that FIG. 10 plots vibration levels for 25 measurements as an example. It can be seen that the vibration levels thus converted and derived by the AD conversion unit 155 (vibration levels indicated by circles in FIG. 10) have reduced variation for each measurement compared to conventional vibration levels (vibration levels indicated by triangles in FIG. 10). This vibration level is output to the derivation unit 16.

[0037] In the following step S7, the derivation unit 16 derives the steam leakage flow rate. Specifically, the derivation unit 16 reads out correlation data corresponding to the model of the steam trap 2 input by the input unit 12 from the storage unit 13. Then, the derivation unit 16 derives the steam leakage flow rate from the vibration level output from the signal processing unit 15 (more specifically, the AD conversion unit 155) based on the correlation data read out from the storage unit 13. As described above, since there is little variation in the vibration level between measurements, a highly accurate steam leakage flow rate can be derived.

[0038] In the following step S8, the steam leakage flow rate derived by derivation unit 16 is displayed on display unit 14. This allows the user to specifically grasp the detected steam leakage flow rate. Note that in this step S8, in addition to the steam leakage flow rate, the vibration level output from signal processing unit 15 (more specifically, AD conversion unit 155) to derivation unit 16 may also be displayed on display unit 14. When step S8 is completed, the steam leakage flow rate detection operation ends.

[0039] As described above, the flow rate detecting device 10 of the embodiment includes the probe 18 (detection unit), the transmitting unit 151, the modulating unit 152, the filter unit 154, and the derivation unit 16. The probe 18 detects the vibration level (vibration) of the steam trap 2 (drain trap) and outputs vibration signals A1 to A3 representing the vibration level. The transmitting unit 151 transmits the reference signal B. The modulating unit 152 frequency-modulates the vibration signals A1 to A3 output from the probe 18 with respect to the reference signal B transmitted from the transmitting unit 151. The filter unit 154 extracts components of a predetermined frequency band Z from the vibration signals A1 to A3 frequency-modulated by the modulating unit 152. The derivation unit 16 derives the steam leakage flow rate from the vibration level corresponding to the vibration signals A1 to A3 extracted by the filter unit 154, based on a correlation between the vibration of the steam trap 2 and the steam leakage flow rate, which has been prepared in advance. Then, the transmitting unit 151 sweeps the frequency of the reference signal B within a predetermined variation range X (predetermined range) over time.

[0040] According to this configuration, the vibration signals A1 to A3 are frequency-modulated while the frequency of the reference signal B is swept within a predetermined fluctuation range X, so that the amplitudes of the vibration signals A1 to A3 are substantially averaged in a certain frequency band. Then, the filter unit 154 extracts the components of the frequency band Z in which the amplitudes of the vibration signals A1 to A3 output from the modulation unit 152 are substantially averaged, thereby obtaining vibration signals A1 to A3 with little variation between measurements. Therefore, it is possible to obtain a vibration level with little variation between measurements. Then, the steam leakage flow rate is derived from such a vibration level, so that a highly accurate steam leakage flow rate can be derived. Therefore, it is possible to improve the accuracy of detecting the steam leakage flow rate.

[0041] In the flow rate detecting device 10 of the above embodiment, the predetermined fluctuation range X (predetermined range) is a range that takes into consideration the frequency variation width Y of the vibration signals A1 to A3 output from the probe 18 and the pass band of the filter section 154.

[0042] According to this configuration, the fluctuation range X is a range that takes into account the variation width Y and the pass band of the filter unit 154, so the amplitude is averaged over the entire pass band of the filter unit 154. This makes it possible to further reduce the variation in the vibration signals A1 to A3, and therefore the variation in the vibration level. This makes it possible to further improve the accuracy of detecting the steam leakage flow rate.

[0043] In the flow rate detecting device 10 of the above embodiment, the probe 18 amplifies and outputs the components at or near the resonant frequency of the probe 18 in the vibration signals A1 to A3 of the detected vibration.

[0044] According to this configuration, the components at or near the resonant frequency in the vibration signals A1 to A3 are amplified, so that the vibration signals A1 to A3 are further emphasized. As a result, the modulation section 152 can more appropriately modulate the vibration signals A1 to A3.

[0045] Other Embodiments As described above, the above embodiment has been described as an example of the technology disclosed in this application. However, the technology of the present disclosure is not limited to this and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate. Furthermore, the components described in the above embodiment can be combined to create new embodiments. Furthermore, the components described in the accompanying drawings and detailed description may include not only components essential for solving the problem, but also components that are not essential for solving the problem in order to exemplify the technology. Therefore, the fact that these non-essential components are described in the accompanying drawings or detailed description should not be interpreted as immediately determining that these non-essential components are essential.

[0046] For example, if the variation in vibration level is reduced to an allowable range, the fluctuation range X of the reference signal B may be set to a range narrower than the variation width Y of the vibration signals A1 to A3.

[0047] Furthermore, the numerical values ​​of the resonance frequency of the probe 18, the fundamental frequency of the reference signal B, and the fluctuation range X of the reference signal B are not limited to those described above.

[0048] Furthermore, while the embodiment described above describes the detection of a steam leakage flow rate as a flow rate, the technology of the present disclosure can also be applied to the detection of a drain flow rate as a flow rate. In this case, the memory unit 13 pre-stores a correlation between the vibration (vibration level) of the steam trap 2 and the drain flow rate. Then, the derivation unit 16 derives the drain flow rate from the vibration corresponding to the vibration signal extracted by the filter unit 154, based on the correlation between the vibration of the steam trap 2 and the drain flow rate. [Industrial Applicability]

[0049] As described above, the technology of the present disclosure is useful for a flow rate detection device. [Explanation of symbols]

[0050] 2 Steam trap (drain trap) 10 Flow detection device 16 Derivation part 18 Probe (detection part) 151 Transmission Department 152 Modulation section 154 Filter section

Claims

1. a detection unit that detects vibration of the drain trap and outputs a vibration signal of the vibration; a transmitter that transmits a reference signal; a modulation unit that frequency-modulates the vibration signal output from the detection unit with respect to the reference signal transmitted from the transmission unit; a filter unit that extracts components of a predetermined frequency band from the vibration signal frequency-modulated by the modulation unit; a derivation unit that derives a flow rate from vibrations corresponding to the vibration signal extracted by the filter unit based on a correlation between the vibration of the drain trap and a flow rate that has been prepared in advance, The transmitting unit sweeps the frequency of the reference signal within a predetermined range over time. A flow rate detection device characterized by:

2. 2. The flow rate detection device according to claim 1, The predetermined range is a range that includes a variation width of the frequency of the vibration signal output from the detection unit. A flow rate detection device characterized by:

3. 3. The flow rate detecting device according to claim 1, The detection unit amplifies and outputs a component of the vibration signal of the detected vibration that is at or near the resonant frequency of the detection unit. A flow rate detection device characterized by:

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