JP7664732B2 - Signal Detection System - Google Patents

Description

The present invention relates to a signal detection system.

Large ships use many rotating machines, including electric motors, and various sensing devices are used to regularly measure the condition of the equipment. However, sudden failures are not uncommon, and the inability to navigate or slow sailing can lead to serious accidents, so maintenance of floating plants is a very sensitive task. Since the conventional methods used on board ships are not sufficient to detect sudden failures, there is a demand for a way to predict early failures in onboard electric motors.

To meet such demands, there is technology that allows abnormality diagnosis without disassembling the device in which the rotating machine is installed. For example, it has been proposed to diagnose abnormalities in rotating parts based on vibration or temperature detection signals from a sensor during inertial rotation of the rotating parts within a specified rotation speed range when the rotary drive means is not energized (see, for example, Patent Document 1). It has also been proposed to detect when the drive current of the electric motor falls below a current threshold value that is equal to or greater than the no-load current of the electric motor and equal to or less than the no-load load current of the rotating machine when the suction port of the rotating machine is closed, and to output the detection result together with an abnormality signal (see, for example, Patent Document 2).

Patent No. 4581693 Patent No. 5561942

However, with the above-mentioned conventional technology, depending on the installation environment of the rotating machine, such as when vibrations generated by other vibration sources are transmitted to the rotating machine being measured via a structure, it is difficult to properly obtain vibration information generated in the rotating machine being measured.

The present invention aims to provide a signal detection system that can properly acquire vibration information generated in a rotating machine being measured, even in a situation where vibrations are propagated to the rotating machine being measured through a structure.

One aspect of the present invention is a signal detection system that detects vibrations in a rotating machine as a measurement target under a condition in which vibrations propagate from another machine through a predetermined structure, the signal detection system comprising:
A first sensor that detects a first signal that varies depending on an operation instruction state for the rotary machine;
a second sensor that directly or indirectly detects a second signal related to vibration generated by the rotating machine;
a control unit that generates a detection instruction signal for controlling a start of detection of the second signal by the second sensor based on the first signal;
A signal detection system comprising:

In such a signal detection system, it is possible to determine whether the rotating machine being measured is in operation or stopped by detecting the first signal that varies depending on the operation instruction state. Therefore, by limiting the measurement period to when the rotating machine being measured is in operation, it is possible to eliminate periods when the influence of vibrations propagating through structures is significant, and to properly obtain vibration information generated by the rotating machine.

The control unit in the signal detection system of the above aspect may include a first control unit that generates a detection instruction signal for controlling the start of detection of the second signal by the second sensor based on the first signal, and a second control unit that controls the start of detection of the second signal by the second sensor based on the detection instruction signal.

The signal detection system of the above aspect may further include a transmitter that transmits the second signal detected by the second sensor to another computing device via wired or wireless communication.

The first sensor in the signal detection system of the above aspect may be a current sensor that detects, as the first signal, the value of a current flowing through a power cable that supplies power to the rotating machine.

The first control unit in the signal detection system of the above aspect may be configured to execute the steps of detecting a current value at a predetermined cycle by the first sensor, and generating a detection indication signal when the AC component is equal to or greater than a predetermined value based on the DC component and AC component contained in the detected current value.

The second control unit in the signal detection system of the above aspect may be configured to execute the steps of detecting the second signal for a predetermined time by the second sensor based on the detection instruction signal, and synthesizing the power spectrum obtained by frequency analysis of the second signal to calculate an overall value.

The transmitter in the signal detection system of the above aspect may be configured to transmit the second signal and the overall value.

The second sensor in the signal detection system of the above aspect may be a sensor that detects at least one of the velocity, acceleration, and acoustic signal of the vibration generated by the first machine as the second signal.

The first sensor and the first control unit in the signal detection system of the above aspect may be provided integrally.

The second control unit in the signal detection system of the above aspect may be provided separately from the first control unit, and the second sensor may be configured to transmit and receive signals to and from the second control unit.

FIG. 2 is a diagram showing an example of the configuration of a signal detection system for detecting a marine electric motor power supply signal and vibration data. 1 is an image showing an entire marine electric motor, which is an example of a rotating machine to be measured. FIG. 2 is a perspective view showing an example of a first sensor (current sensor) installed on a power cable. FIG. 1 is a diagram illustrating an example of an operation flow of the signal detection system. 1A is a graph showing measurement data obtained in Comparative Example 1 of the present invention, and FIG. 1B is a graph showing measurement data obtained in Example 1 of the present invention. 1 is a trend graph showing the results of a monitoring test carried out in Example 2 of the present invention. 13 is a graph showing the results of FFT analysis of detection data (A) before open inspection and (B) after open inspection in the monitoring test of Example 2.

The configuration of the present invention will be described in detail below based on an example of an embodiment shown in the drawings.

The signal system of the present invention is a signal detection system that detects vibrations in a rotating machine as a measurement target under conditions in which vibrations are propagated from another machine through a specified structure. Below, one embodiment of the present invention will be described, giving an example of the application to a system for detecting abnormalities in a marine electric motor 100 of a ship 1000 (see FIG. 1, etc.).

The marine electric motor 100 that is the subject of abnormality detection is composed of a motor 102, a power cable 104 for the motor 102, a blower unit 106 driven by the motor 102, etc. (see Figures 1 and 2). The blower unit 106 is driven when the diesel engine 200 is started, etc., and supercharges the diesel engine 200 when it is started, etc.

The signal detection system 1 of this embodiment, which detects an abnormality in a marine electric motor 100, includes a first sensor 10, a second sensor 20, a transmitter 30, a receiver 40, a control unit, etc. (see FIG. 1, etc.). By configuring such a signal detection system 1 to transmit and receive data between the transmitter 30 installed at any position in the engine room of a large ship, for example, and the receiver 40 (possibly via a repeater), it becomes possible to collect data at a position away from the rotating machine that is the target of abnormality detection and to perform analysis of the data.

The first sensor 10 is used as a sensor (trigger input device) that detects a first signal that varies depending on the operation instruction state to the marine motor 100. In this embodiment, a current sensor (motor operation detection sensor) that detects an electric signal of the power cable 104 is adopted, and the current sensor is used as the above-mentioned first sensor 10 (see FIG. 3). The current sensor is preferably provided on the power cable 104 and further provided close to the motor 102. When power is supplied to the motor 102, a current flows through the power cable 104. The power supplied to the motor 102 varies depending on the operation instruction state of the motor 102, for example, whether the motor 102 is stopped or operating. As a result, the current flowing through the power cable 104 varies depending on the operation instruction state to the motor 102. The above-mentioned current sensor detects the current value at this time and transmits the detection signal (first signal) to the first control unit 11 described later (see FIG. 1, etc.).

The first control unit 11 generates a trigger signal (detection instruction signal) that indicates that it is suitable timing for vibration measurement by the second sensor 20 (i.e., a signal for starting detection by the second sensor 20) based on the detection signal (first signal) transmitted from the first sensor 10, as described below. A suitable timing for vibration measurement by the second sensor 20 is, for example, a timing when the motor 102 is being driven.

The first signal that varies depending on the operating instruction state may be a signal that can be obtained from a control system of the rotating machine, for example, a signal that instructs the rotating machine on the rotation speed. The first signal that varies depending on the operating instruction state may also be a signal that can be obtained from outside the rotating machine without connecting to the control system of the rotating machine, for example, as described above, a current signal that indicates the amount of power supplied to the rotating machine. If the first signal is a signal that can be obtained without connecting to the control system of the rotating machine, this is preferable in that the operating state of the rotating machine can be grasped without modifying the existing control system of the rotating machine.

The second sensor 20 is a sensor that directly or indirectly detects a second signal related to vibrations generated in the marine electric motor 100. In this embodiment, a vibration sensor attached to the housing of the motor 102 is used to detect a signal related to vibrations (second signal) (see FIG. 1). The detected signal is transmitted to the transmitter 30. The signal related to vibrations (second signal) detected by the second sensor 2 may be at least one of the speed, acceleration, and acoustic signal of the vibrations generated by the motor 102. The second sensor 20 may directly detect the vibrations generated by the marine electric motor 100 as at least one physical quantity of the acceleration, speed, and position of the marine electric motor 100. In this case, it is preferable that the second sensor 20 is provided in the marine electric motor 100. In addition, the second sensor 20 may indirectly detect the vibrations generated by the marine electric motor 100, for example, as an acoustic signal. In this case, it is preferable that the second sensor 20 is provided at a position separated from the marine electric motor 100. In addition, a member that transmits vibrations may be provided between the second sensor 20 and the marine electric motor 100, which is the object that generates the vibrations, and the second sensor 20 may indirectly detect the vibrations via the member.

The transmitter 30 is a device that transmits a second signal (vibration value) and other information on the equipment operating conditions to the receiver 40 via wireless communication. The receiver 40 is a device that receives the signal transmitted from the transmitter 30.

In this embodiment, a wireless sensor network type wireless transmitter (child device) and receiver (parent device) capable of wireless communication are used as the transmitter 30 and receiver 40. When such a wireless transmitter/receiver is adopted,
- By simply attaching a sensor to the equipment to be measured, it is possible to easily monitor the status of equipment. - By connecting to the Internet, it is possible to perform advanced diagnosis automatically. - Wiring work associated with installation is unnecessary or extremely small. - Highly accurate equipment status management is possible at low cost. - It is possible to start with a small-scale introduction to important equipment and then expand later. - As data is collected automatically, there is no need for measurement work. - Advanced diagnostic reports can be obtained through remote automatic diagnosis. - Automatic data collection is possible using an online system. - Web-based automatic diagnosis is possible by utilizing previous diagnostic know-how, etc.

In addition, the adoption of a wireless transmitter/receiver that can provide the above-mentioned advantages can, for example, eliminate the need for a conventional online continuous monitoring system.
・Wiring work required ・High installation cost ・Expansion and relocation are difficult (construction, settings, etc.)
・Not connected to automated diagnosis by experts ・Only available for important equipment. Furthermore, conventional offline diagnostic devices (e.g. portable diagnostic devices) have various issues.
This will lead to solving various issues such as: - Measurement work is required - Measurement variations can occur - The measurement cycle is long, making it difficult to detect sudden abnormalities - There are areas that cannot be measured - Automated diagnosis by experts is manual - It is difficult to expand the number of devices to be diagnosed - There are cases where this can lead to a decrease in diagnostic accuracy.

In this embodiment, the transmitter (child unit) 30 is installed near the motor 102 and is wired to the first sensor 10 and the second sensor 20 by cables 10a and 20a, respectively (see FIG. 1). A signal is wirelessly transmitted from the transmitter 30 to the receiver (parent unit) 40. Although not specifically shown in this embodiment, if the signal strength cannot be ensured because the distance between the transmitter 30 and the receiver 40 exceeds a predetermined value, a repeater that relays the signal may be provided between the transmitter 30 and the receiver 40.

The control unit includes an arithmetic device that performs various control processes in the signal detection system 1. The specific configuration of the control unit is not particularly limited. As an example, the control unit in the signal detection system 1 of this embodiment includes a first control unit 11 and a second control unit 32. The first control unit 11 generates a detection instruction signal for controlling the start of detection of the second signal by the second sensor 20 based on the first signal (driving detection signal) detected by the first sensor 10. The second control unit 32 controls the start of detection of the second signal by the second sensor 20 based on the detection instruction signal.

In this embodiment, the first control unit 11 is configured, for example, by a control circuit (microcomputer) that is integrated with the first sensor 10. It does not matter whether the circuit is an analog circuit or a digital circuit. The second control unit 32 is provided, for example, in the transmitter 30 (see FIG. 1). The first sensor 10 and the first control unit 11 may be integrated or may be provided separately. The second sensor 20 in the signal detection system 1 of this embodiment is configured to transmit and receive signals to and from the second control unit 32.

The signal detection system 1 of this embodiment also includes a calculation device that performs various calculations. In this embodiment, the calculation element of the control unit (for example, the first control unit 11 or the second control unit 32) described above may be used as the calculation device. The specific form of the calculation device is not particularly limited, and for example, the calculation device provided in the transmitter 30 or the receiver 40 may be used as the calculation device of the system as it is. The signal detection system 1 may include not only such a calculation device but also other calculation devices. Specific examples of other calculation devices include a repeater (not shown) or a personal computer with analysis software installed. The second sensor 20 in the signal detection system 1 of this embodiment transmits the detected second signal (vibration data) to the other calculation device as described above.

Next, various processes such as signal detection, external operation, and signal transmission in the signal detection system 1 of this embodiment will be described with examples (see FIG. 4). In this embodiment, the first control unit 11 and the second control unit 32 are set for operation in the setting mode, and operate in the measurement mode according to the conditions set in the setting mode.

[Settings mode]
In the setting mode, the operation settings of the trigger input device and the transmitter, in other words, the settings for the first control unit 11 and the second control unit 32, are performed. In this embodiment, the operation settings for the trigger input device correspond to the settings for the first control unit 11, and the operation settings for the transmitter 30 correspond to the settings for the second control unit 32. The operation settings may be performed by a general-purpose PC on which a specific software is installed. The transmitter 30 is configured to be capable of transmitting and receiving data to and from the general-purpose PC wirelessly and/or via a wire. The general-purpose PC can perform the operation settings of the trigger input device via the transmitter 30.

Here, the general-purpose PC may be connected to the transmitter 30 (child unit) by wire (e.g., LAN cable) or wirelessly, and may be connected to the receiver 40 (parent unit) by wire (e.g., LAN cable) or wirelessly, and connected to the transmitter 30 via the receiver 40 (parent unit). At this time, the general-purpose PC transmits and receives data to the transmitter 30 via the receiver 40. That is, when a setting instruction is given to the receiver 40, the instruction is transmitted to the transmitter 30 by wireless communication (possibly via a repeater). Furthermore, the instruction is transmitted to a trigger input device that is connected to the transmitter 30 by wire.

In the setting mode, first, the sleep time of the trigger input device (first control unit 11) is set. The sleep time determines the interval at which the current sensor detects the current supplied to the marine electric motor 100. Note that the current sensor may be a sensor that detects magnetic fluctuations in the X, Y and Z axis directions to measure whether a predetermined amount of current is flowing. For this reason, a magnetic sensor is described in step SP1 of FIG. 4. The sleep time is, for example, 5 minutes.

Furthermore, as a setting for the trigger input device (first control unit), a reference value for AC/DC judgment used in step SP3 of FIG. 4 described later, that is, a reference value for whether or not the current value acquired by the current sensor contains an AC component of a predetermined value or more, is set. The presence of an AC component of a predetermined value or more indicates that the motor 102 is operating. In this embodiment, in order to set the reference value, the current sensor detects the current value while the motor 102 is operating. The DC component is extracted as an offset value from the waveform of the detected current value, and the reference value is set based on the offset value. The reference value may be the offset value itself, or may be a value obtained by adding a predetermined value to the offset value. Here, the reference value may be set automatically based on the predetermined software described above, or may be set manually by an operator checking the waveform of the current value.

In the setting mode, the measurement time of the vibration sensor is set as a setting for the transmitter (second control unit 32). The measurement time is, for example, one minute. Note that, if the rotation speed of the motor 102 can be estimated from the current value detected by the current sensor, the measurement time may be determined by the rotation speed of the motor 102. In this case, the measurement time is, for example, five rotations.

In the setting mode, the measurement period by the second sensor 20 is set. More specifically, in this embodiment, the reception exclusion time of the detection instruction signal generated in the first control unit 11 (trigger input device) is set as a setting for the transmitter (second control unit 32). During the reception exclusion time, the second control unit 32 does not perform detection by the vibration sensor even if a detection instruction signal is transmitted from the first control unit 11. That is, the reception exclusion time determines the measurement period in which the vibration sensor detects the vibration of the rotating device to be measured. In other words, the reception exclusion time determines the time from when the vibration sensor detects a signal (second signal) related to the vibration generated by the measurement object at a certain point in time to the next point in time. The reception exclusion time is, for example, one day. In this embodiment, the reception exclusion time is configured to be set in order to determine the measurement period by the vibration sensor, but this is not limited to the method as long as it is a method for setting the measurement period by the vibration sensor. For example, instead of the setting for the second control unit 32, the generation exclusion time of the detection instruction signal or the output exclusion time of the detection instruction signal may be set as a setting for the first control unit 11 (trigger input device).

As mentioned above, the first control unit 11 and the second control unit 32 may be integrated into a single computing device. Therefore, settings in the setting mode may be performed for a single control unit (computing device).

After the settings for the first control unit 11 and the second control unit 32 are completed, the first control unit 11 and the second control unit 32 are set to the measurement mode.

[Measurement mode]
In the measurement mode, the first control unit 11 and the second control unit 32 operate according to the conditions set in the setting mode. As shown in FIG. 4, the processes of steps SP1 to SP4 are executed by the first control unit 11, and the processes of steps SP5 to SP7 are executed by the second control unit 32.

<Step SP1>
In step SP1, the first control unit 11 waits for a preset sleep time (for example, 5 minutes).

<Step SP2>
In step SP2, the first control unit 11 activates the current sensor and acquires the current value detected by the current sensor. The current sensor may be in a constantly activated state. However, from the viewpoint of reducing power consumption, it is preferable to stop the operation of the current sensor during the sleep time.

<Step SP3>
In step SP3, the first control unit 11 judges whether the AC component included in the current value is equal to or greater than a predetermined value. More specifically, the first control unit 11 compares the acquired current value with a reference value previously set in the setting mode, and judges that the AC component included in the current value is equal to or greater than a predetermined value when the acquired current value is greater than the offset value by a predetermined value or more. Note that the AC component included in the current value being equal to or greater than a predetermined value indicates that the motor 102 is operating. If the answer is YES in step SP3, proceed to step SP4. If the answer is NO in step SP3, return to before step SP1 and wait during the sleep time.

<Step SP4>
In step SP4, the first control unit 11 outputs a trigger to the second control unit 32. That is, the first control unit 11 outputs a detection instruction signal to the second control unit 32 to instruct the second control unit 32 to obtain a signal (second signal) related to the vibration of the measurement target by the vibration sensor.

<Step SP5>
In step SP5, the second control unit 32 acquires a trigger, that is, acquires the detection instruction signal output from the first control unit 11.

<Step SP6>
In step SP6, the second control section 32 judges whether the trigger reception stop state has ended, in other words, whether the trigger reception ignoring time set in the setting mode has elapsed. If the answer is YES in step SP6, the process proceeds to step SP7, and if the answer is NO in step SP6, the process returns to before step SP1.

<Steps SP7 to SP10>
In step SP7, the second control unit 32 detects (measures) a signal (second signal) related to the vibration of the measurement target by using the vibration sensor (second sensor). Furthermore, the second control unit 32 performs at least one of FFT analysis and data compression on the detection value obtained at the measurement time set in the setting mode. The data compression may be performed by reducing the time resolution of the second signal, or by calculating an overall value. In this embodiment, the second control unit 32 provided in the transmitter 30 transmits at least one of the detection value (raw data) of the detected second signal, the result of FFT analysis on the detection value, and the compressed value of the raw data (e.g., overall value) via the receiver 40 to a calculation device (e.g., a general-purpose PC) in which analysis software for determining the presence or absence of an abnormality in the rotating device is installed (step SP8). After that, the calculation device performs analysis, and the analysis result is displayed on a predetermined display unit (step SP9).

As described above, the first control unit 11 detects the current value at a predetermined cycle using the first sensor 10. Furthermore, the first control unit 11 generates a detection instruction signal based on the direct current component and alternating current component (DC/AC) contained in the detected current value when the AC component is equal to or greater than a predetermined value. In this manner, the first control unit 11 in the signal detection system 1 of this embodiment determines whether or not to generate a trigger signal based on the DC/AC value contained in the current value. In this embodiment, the first control unit is a microcomputer, and is provided integrally with the first sensor 10.

The second control unit 32 also has a processor for calculating an overall value (a value obtained by summing up the sound pressure levels at each frequency obtained as a result of frequency analysis using FFT). In the present embodiment, the second control unit 32 provided in the transmitter 30 is configured to be able to transmit to the receiver 40 all of the detection value ("raw data") of the second signal indicating the vibration detected by the vibration sensor, the "result of FFT analysis of the raw data," and the "overall value (O/A)," or any selected data among them. As described above, the signal detection system 1 in the present embodiment is configured to be able to arbitrarily set the measurement period of the vibration sensor (second sensor 20), but in addition to this, in the setting mode, the calculation period of the overall value may be configured to be individually set. Furthermore, in the setting mode, the signal detection system 1 in the present embodiment may be configured to be able to individually set the timing of transmitting at least one piece of information among the "raw data," "result of FFT analysis," and "overall value (O/A)" or a plurality of pieces of information from the transmitter 30 to the receiver 40 for each piece of information to be transmitted. For example, the "overall value," which contains relatively less information than the "raw data," may be set to be sent more frequently than the "raw data."

The signal detection system 1 of this embodiment may have a "fixed cycle mode" in which the measurement cycle of the second sensor 20 is set to a predetermined cycle as described above. Furthermore, the signal detection system 1 of this embodiment may have a "command mode" in which an operator uses an arbitrary computing device (e.g., a general-purpose PC) to give an instruction to the second sensor 20 via the receiver 40 and the transmitter 30, thereby acquiring a detection value at the time of the instruction. Furthermore, the signal detection system 1 of this embodiment may have a "direct acquisition mode" in which an operator connects an arbitrary computing device (e.g., a general-purpose PC) to the transmitter 20 by wire and can directly acquire the detection value of the second sensor 20 by contact input to the transmitter 30. The "fixed cycle mode", "command mode", and "direct acquisition mode" may be configured to be executable in parallel or independently.

The second control unit 32 in the signal detection system 1 of this embodiment causes the second sensor 20 to detect the second signal for a predetermined time based on the detection instruction signal. Furthermore, the second control unit 32 of this embodiment calculates an overall value by synthesizing a power spectrum obtained by frequency analysis of the second signal (a signal related to vibration of the motor 102). The transmitter 30 transmits the second signal and the overall value to the receiver 40.

As described above, the signal detection system 1 of this embodiment determines whether the rotating machine to be measured (in this embodiment, the marine electric motor 100) is in operation or not by detecting the first signal that varies depending on the operation instruction state, and based on the determination result (trigger signal), it is possible to set the measurement period only when the motor 102 of the marine electric motor 100 is in operation. This makes it possible to exclude periods when the influence of vibrations propagating through structures, etc. is large (i.e., in the case of the marine electric motor 100, periods when power to drive the motor 102 is not being supplied), and to properly obtain vibration information generated by the rotating machine.

The rotating machine to be measured is not limited to an electric motor, and may be a rotating device driven by an electric motor, such as a blower, pump, or fan, in which an abnormality in the rotating machine manifests itself as vibrations that are different from normal vibrations.

We conducted various studies and tests on the case where the rotating machine to be measured for signal detection is a ship's auxiliary blower. The results are explained below (see Figure 5, etc.).

[Study Example 1]
The main causes of auxiliary blower failures, the parameters suitable for detecting abnormalities leading up to failure, and the occurrence frequencies are known to be as follows (see Table 1).

As for the motor that drives the auxiliary blower, similarly to the above, the main causes of failure, the parameters suitable for detecting abnormalities leading up to failure, and the occurrence frequency are known to be as follows (see Table 2).

In light of the above, most abnormal symptoms in blowers can be identified by measuring vibrations, specifically by calculating the rotation frequency [Hz] by dividing the equipment's rotation speed by 60 [seconds]. However, as explained in the above embodiment, in doing so, it is necessary to take into full consideration the operating state of the equipment being measured and the vibrations from surrounding equipment (e.g., the main engine of a ship) that may affect the detection of abnormalities in the equipment being measured, and further investigation was carried out with this point in mind.

Next, noise data was obtained after implementing measures using the signal detection system 1 according to the present invention, and compared with noise data obtained before implementing the measures. This is explained below as Example 1 and Comparative Example 1 (see FIG. 5).

[Comparative Example 1]
The motor 102 for an auxiliary blower in a ship was used as the measurement target, and vibration diagnosis tests were conducted under conditions where the influence of vibrations from the ship's main engine was significant. An example of noise data obtained at this time is shown in the figure (see FIG. 5(A)). In this noise data, "main engine RPM" indicates the RPM [mm/s] of the main engine (M/E), "blower operation" indicates the operation state of the auxiliary blower, that is, whether the motor 102 is in "RUN" state or "STOP" state, and "vibration velocity value" is measurement data (one-hour average of overall value calculated from the speed) obtained by processing a signal (second signal) related to vibration detected by a vibration sensor.

The results of the above test confirmed that the vibration velocity value was high even though the auxiliary blower was stopped (meaning that the measurement data contained disturbances caused by vibrations from the main engine, etc., propagating through structures, etc., and this had a large impact) (see Figure 5 (A)). Under these circumstances, the vibration velocity value fluctuated widely and was unstable, ranging from 0.5 to 4 mm/s (see the area enclosed in a rectangular frame in Figure 5 (A)), making it difficult to set a threshold value, and it was concluded that appropriate condition monitoring would not be possible with vibration diagnosis unless appropriate measures were taken.

[Example 1]
Considering that the influence of the vibration of the main engine continues even when the auxiliary blower is stopped, it is meaningless to compare the measured values to observe the condition of the auxiliary blower at fixed points, and it is more important to focus on the rotation frequency generated by the auxiliary blower when the auxiliary blower is operating and measure it so as to eliminate the influence of disturbance as much as possible. Based on this knowledge, after implementing noise countermeasures, a vibration diagnosis test was performed under the same conditions as those of the above-mentioned Comparative Example 1. An example of the noise data obtained at this time is shown in the figure (see FIG. 5(B)). In addition, it was confirmed by frequency analysis whether there was an abnormality in the auxiliary blower, more specifically, whether there were any frequency characteristics that are said to appear at each abnormality symptom, and then, as an example, a threshold was set. As a result, in this example, it was concluded that if a threshold value of approximately 1.5 [mm/s] is set, it is possible to determine that the blower is normal if it falls below this threshold value. As the threshold value, a standard for determining whether the condition is good or bad is set, and a value that serves as a guide for monitoring, such as normal if it is within 0 to 1, is used.

[Example 2]
Monitoring tests suited to the shipboard environment were carried out for the first, second and third periods, and the results are described below as Example 2 (see Figs. 6 and 7).

The speed values of the auxiliary blower data detected during the above period are shown on a trend graph (see Figure 6). The trend graph is divided into three ranges according to the speed [mm/s] value: normal range, caution range, and abnormal range. When compared with these ranges, it was found that many of the speed values were in the abnormal range during the first period (January to April 2020) (see symbol *1 in Figure 6). After that, an open inspection was conducted during the second period (early May 2020), and monitoring was conducted during the third period (mid-May 2020), and it was found that the speed values had decreased (see symbol *2 in Figure 6). In addition, the results of FFT analysis of the detection data before and after the open inspection also confirmed that the speed values had decreased (see Figures 7 (A) and (B)).

The present invention is suitable for use in a signal detection system that detects vibrations in a rotating machine as a measurement target in a situation where vibrations are transmitted from another machine through a specified structure.

1...signal detection system, 10...first sensor, 10a...cable, 11...first control unit, 20...second sensor, 20a...cable, 30...transmitter, 32...second control unit, 40...receiver, 100...marine motor (rotating machine to be measured), 102...motor, 104...power cable, 106...blower unit, 200...diesel engine (other machine), 300...casing (structure) constituting the engine

Claims (7)

A signal detection system for detecting vibrations in a rotating machine as a measurement target in a situation where vibrations propagate from a machine other than a rotating machine through a housing constituting the other machine , the signal detection system comprising:
A first sensor that detects a first signal that varies depending on an operation instruction state for the rotary machine;
a second sensor that directly or indirectly detects a second signal related to vibration generated by the rotating machine; and
a control unit that generates a detection instruction signal for controlling a start of detection of the second signal by the second sensor based on the first signal ,
The control unit is
a first control unit that generates a detection instruction signal for controlling a start of detection of the second signal by the second sensor based on the first signal;
a second control unit that controls a start of detection of the second signal by the second sensor based on the detection instruction signal,
the first sensor is a current sensor that detects, as the first signal, a value of a current flowing through a power cable that supplies power to the rotating machine;
The first control unit is
detecting a current value at a predetermined period by the first sensor;
generating the detection indication signal when the AC component is equal to or greater than a predetermined value based on a DC component and an AC component included in the detected current value;
A signal detection system configured to: The device further includes a transmitter that transmits the second signal detected by the second sensor to another computing device by wired communication or wireless communication.
The signal detection system of claim 1 . The second control unit is
detecting the second signal for a predetermined time by the second sensor based on the detection instruction signal;
a step of calculating an overall value by synthesizing a power spectrum obtained by frequency-analyzing the second signal;
3. The signal detection system of claim 2 , configured to perform the following: The signal detection system of claim 3 , wherein the transmitter is configured to transmit the second signal and the overall value. The signal detection system according to any one of claims 1 to 4 , wherein the second sensor is a sensor that detects at least one of a velocity, an acceleration, and an acoustic signal of vibration generated by the rotating machine as the second signal. 6. The signal detection system according to claim 1 , wherein the first sensor and the first control unit are integrally provided. The signal detection system according to any one of claims 1 to 6, wherein the second control unit is provided separately from the first control unit, and the second sensor is configured to transmit and receive signals between the second control unit and the second sensor.