KR200298995Y1 - Torsional vibration monitoring system - Google Patents

Abstract

The present invention is a series of machine detection systems that provide to the driver the torsional vibration analysis information generated by the axis system device 10 by constantly monitoring and analyzing the torsional vibration state during operation of the power transmission shafting system, in particular an alarm to the driver when abnormal vibration occurs The present invention relates to a torsional vibration monitoring system that provides information on causes of abnormal vibrations.

Torsional vibration monitoring system according to the present invention for achieving the above object, attached to the shaft system device 10 detects the torsional vibration generated in the shaft system device 10 and outputs an electrical signal corresponding thereto; The torsional vibration analysis information generated by the control unit 8 and the control unit 8 generating the torsional vibration analysis information by comparing and evaluating the electrical signal generated by the detection unit 13 based on a predetermined set value are It includes a panel portion 9 for displaying to.

Description

Torsional Vibration Monitoring System {TORSIONAL VIBRATION MONITORING SYSTEM}

The power transmission shaft system 10, for example, a drive shaft system for a ship propulsion shaft system powered by a diesel engine or a steam turbine as a power source inevitably twists due to pulsation of transmission torque during operation, natural vibration of the shaft system, and the like. Vibration occurs, and its amount varies depending on the measurement position, operating speed, load conditions, and the performance of the associated components.

Excessive torsional vibration causes damage and fatigue destruction of the shaft system or related components, so the torsional vibration state generated in the shaft system 10 should be continuously monitored, especially in the propulsion shaft of a ship as shown in FIG. Damage and breakage of the device 10 results in loss of propulsion of the ship, which leads to a great loss of life and economic loss, so some ship safety regulations maintain the performance of torsional vibration dampers 51, elastic couplings 54, etc. State monitoring is mandatory.

Therefore, in order to prevent damage of the shafting device 10 or minimize damage parts and to increase the operation rate of the shafting device 10, the abnormal vibration occurs by continuously monitoring and analyzing the torsional vibration state generated in the shafting device 10. There is a need for a system that can issue an alarm and provide the driver with information such as the cause of abnormal vibrations quickly.

Torsional vibration is usually measured as an amount of change in angle or angular velocity, but depending on the characteristics of the shafting device 10, even a small angular velocity vibration amount may damage the shafting device 10, and even a high angular velocity vibration amount may be used for the shafting device 10. There may not be a problem with the safety. This is because the specifications and mechanical characteristics of the related parts differ depending on the shafting device 10. In order to grasp the characteristics of the shafting device 10, it is necessary to perform a system analysis on the shafting device 10 by a computer program. .

However, in order to perform such a system analysis, components such as those shown in FIG. 4, for example, torsional vibration dampers 51, pistons 52, crankshafts 53, elastic couplings 54, propellers 55 It is necessary to know the elastic modulus (k), the damping coefficient (c), the inertial mass (m), etc., which are related values of vibration characteristics, and so on, and require an advanced computer program and a skilled technician.

Conventionally, there have been devices for measuring torsional vibration, but only the verification of the design and manufacturing results of the shaft system 10 by one-time simple measurement and analysis, and the functional parts related to the shaft system 10, for example, torsional vibration damper (51), it is difficult to check when the donation decreases due to damage, abrasion, etc. of the elastic coupling 54, etc., and the structural problems of the shaft-type device 10 restrict the mounting of the detectors 14 and 15 and the selection of the type. There were still problems such as trend analysis and the inability to accumulate data for introducing a preventive maintenance system.

In addition, conventionally, a system analysis of the shaft system device 10 is required to determine the measurement and analysis results, and the analysis criteria and the determination criteria when the measurement result deviation occurs are ambiguous, and the characteristic factors of related components, that is, the elastic modulus (k), If the damping coefficient (c), the inertial mass (m) and the like were not known, the analysis was impossible.

Accordingly, the present invention is to overcome the above-mentioned problems, by continuously monitoring the torsional vibration state of the shaft system device 10 to generate a warning of visual and audio signals when an abnormality such as degradation of the performance of the functional product, damage of the related parts and the driver To provide a system that can visually display abnormal cause information.

Another object of the present invention is to provide a system having a so-called self-learning function that can set an abnormal vibration determination reference value based on the data accumulated by the test operation when there is no existing analysis data for the shaft system 10. To provide.

1A shows a detection unit combined with an axis system of a torsional vibration monitoring system according to an embodiment of the present invention;

1B to 1C are diagrams illustrating a case where a detection unit is implemented as an inductive or optical detector;

2 is a diagram illustrating a torsional vibration signal processing process of a torsional vibration monitoring system according to an embodiment of the present invention;

3 is a view showing an appearance of a panel unit connected to a detection unit of a torsional vibration monitoring system according to an embodiment of the present invention;

4 is a view showing the configuration of a ship propulsion shaft system using a diesel engine as a power source according to an embodiment of the present invention.

<Short description of drawing symbols>

8: Control unit 9: Panel part

10: shaft system 11: vibration gear

12: phase difference 13: detection unit

14: vibration detector 15: phase detector

16: liquid crystal display 40: signal regulator

41: program logic element 42: digital signal processing element

45: digital-to-analog signal converter 46: relay circuit

In order to achieve the above object, the present invention, the detection unit 13 and attached to the shaft device 10 detects the torsional vibration generated in the shaft device 10 and outputs an electrical signal corresponding thereto, and the detection unit 13 A control unit 8 for generating torsional vibration analysis information by comparing and evaluating the electrical signal generated by the predetermined setting value, and a panel for displaying the torsional vibration analysis information generated by the control unit 8 to a user. And a controller (9), wherein the controller (8) extracts a valid signal by removing noise from the signal output from the detector (13), and electrically connects the detector (13) with the controller (8). A digital scene for comparing and analyzing the independent signal conditioner 40 and the valid signal from the signal conditioner 40 based on a predetermined set value according to a programmed algorithm. A data memory 43, 44 for storing the valid signal, the set value or comparative analysis data thereby and supplying it to the digital signal processing element 42 as necessary; 40, direct current, alternating current, or AC according to the situation of the control unit 8 and the program logic element 41 which controls the digital signal processing element 42, the data memories 43 and 44, and controls the input / output of the system. It is characterized in that it comprises a power supply unit 47 for supplying power in the form of both direct current and alternating current.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In this case, the same reference numerals are used to refer to the same elements, even though they are shown in different drawings, and detailed descriptions of related well-known functions or configurations are provided in describing the present invention. If it is determined that the subject matter may be obscured, the detailed description thereof will be omitted.

FIG. 1A shows a detector 13 combined with an axis system 10 of a torsional vibration monitoring system according to an embodiment of the present invention. The detector 13 includes a vibration gear 11, a phase gear 12, a vibration detector 14, and a phase detector 15.

According to an embodiment of the present invention, the electrical signal output from the detection unit 13 of the present invention is characterized in that the pulse wave, the torsional vibration is characterized by the change in the pulse interval in the pulse wave.

When torsional vibration occurs in the shafting device 10, the angle or angular velocity of the shafting device 10 is changed in proportion to the amount of torsional vibration. In this case, as shown in FIG. 1A, when the gears 11 and 12 are attached to the outer circumferential surface of the shaft system 10 and the intervals of the pulses generated by using the detectors 14 and 15 are measured, torsional vibration is generated. Otherwise, the interval of pulses is constant, and when torsional vibration occurs, the interval of pulses changes in proportion to the amount of torsional vibration. At this time, the amount of torsional vibration can be known by calculating the change amount of the pulse interval.

The vibration gear 11 may have a disk shape having a plurality of protrusions or slits at equal intervals and generate a plurality of pulses for each rotation of the shaft system 10. The phase gear 12 has one protrusion or slit similar to the vibration gear 11 to generate only one pulse per one rotation of the shaft system 10. At this time, existing accessories such as crank gears, starting ring gears and turbine blades of internal combustion engines can be utilized or new dedicated gears can be attached.

The vibration detector 14 joins the vibration gear 11 to convert a mechanical pulse signal generated from the vibration gear 11 into an electrical pulse signal according to whether the vibration gear 11 protrudes or a slit passes through the detector. To 8). The phase detector 15 also works in conjunction with the phase gear 12 to convert a mechanical pulse signal generated from the phase gear 12 into an electrical pulse signal according to whether the protrusion of the phase gear 12 passes through the detector or the slit. To 8). It is possible to use an inductive, capacitive or optical detector according to an embodiment of the present invention.

Figure 1b shows the internal structure and appearance of an inductive detector used as the vibration and phase detector of the present invention. The inductive detector is a detector most commonly used for measuring the rotational speed of a rotating body, and the basic structure thereof includes a magnet 73 and a coil 72 inside the case 71 as shown in FIG. The epoxy 74 resin is filled and fixed firmly. In addition, a screw is machined outside the case 71 so that it can be easily attached to the structure.

Referring to the principle of operation, first, when a magnetic material passes through the detector end, the electromotive force is generated in the coil 72, and when there is no magnetic material, the electromotive force is dissipated. If this operation is repeated and the plurality of protrusions pass continuously, the output signal outputs a signal of a continuous waveform. At this time, since the output signal has a weak self electromotive force, noise may be mixed between the detector and the signal processor. Therefore, the signal amplification and the converter 75 are incorporated to correct an incomplete signal, and the output voltage is also amplified by several volts. To print.

Figure 1c shows the internal structure and appearance of the optical encoder used as the detection unit of the present invention. In the case of configuring the detection unit using an optical encoder, after processing the slit 79 on the opaque disk 81 integrated with the rotating shaft, the light is emitted from the light source 78 on one side of the disk, and the light receiving sensor 80 on the opposite side of the disk is processed. ) To detect the light. At this time, when the disk 81 rotates together with the rotation shaft, the light flickers on the light receiving sensor 80 side according to whether the slit 79 passes, and the light receiving sensor 80 converts the light into an electrical signal and outputs the light.

In the case of using the optical encoder as the detection unit of the present invention, the number of slits 79 can be processed up to several thousand according to the precision machining of the rotating disc 81, and the resolution is excellent, and the slit 79 and the light receiving sensor 80 By installing a plurality of) in the radial direction, the vibration detector and the phase detector can be implemented as one light source 78 at once. However, since the rotary shaft system and the rotary shaft must be directly connected, a structure and space for installing an encoder at the end of the rotary shaft system have a disadvantage in that the rotary shaft system needs to be directly connected.

According to an embodiment of the present invention, if the optical encoder can be attached to the end of the shaft system device 10, the gears 11 and 12 and the detectors 14 and 15 may be integrated to form the detector 13 having a simple structure. Can be. In this case, the torsional vibration is recognized as an optical signal and converted into an electrical signal.

Figure 2 shows a torsional vibration signal processing of the torsional vibration monitoring system according to an embodiment of the present invention.

The signal output from the detector 13 is transmitted to the controller 8, and the controller 8 controls the signal conditioner 40, the program logic element 41, the digital signal processing element 42, and the data memory 43, 44. And additionally include communication ports 26,27, digital-to-analog signal converters 45, and relay circuits 46, in some embodiments.

The signal regulator 40 receives a pulse generated by the detector 13, removes electrical mechanical noise, etc. generated from a peripheral device, extracts a valid signal, and electrically insulates the detector 13 from the controller 8 to isolate the circuit. It is configured to make a signal analysis, such as to correct the shape of the output signal, and to adjust the easy to analyze.

The program logic element 41 controls the overall input / output flow of the system, adjusts the path input from the signal regulator 40, and adjusts or communicates with the user's input switches 20, 21, 22, 23, and 24. The digital signal processing element 42, the storage device, the liquid crystal display device 16, the relay circuit 46 and the like are adjusted and controlled according to the input conditions of the external equipment such as an external computer.

The digital signal processing element 42 analyzes, compares and evaluates the torsional vibration signal according to an algorithm programmed with the core device of the system. The pulse signal input from the program logic element 41 may cause distortion of the pulse signal due to structural machining errors of the gears 11 and 12 or vibration of the detection unit 13, and these may be mistaken as normal vibration signals. Includes the ability to eliminate these factors as they may affect the results of the analysis.

The digital signal processing element 42 may selectively analyze the measured torsional vibration signal in order to provide useful torsional vibration analysis information to the user, such as a time axis graph, an order axis graph, a speed axis graph, etc. It is provided to the user in the form of comparing and analyzing the back and generates an alarm signal when the reference value is exceeded. The data for the comparison and analysis can be input and changed by the user as an environment setting value, for example, the number of torsional vibration input pulses per rotation of the shaft device 10, the position of the phase detection pulse (angle), It includes reference values for alarm generation.

The function of the digital signal processing element 42 is processed according to a programmed algorithm, which is protected from being erased or modified by the user except for some user options such as setting value change, thereby ensuring reliability.

The data memories 43 and 44 store data processed by the digital signal processing element 42 and the program management element and supply them to them as necessary.

According to another embodiment of the present invention, the set value for providing the torsional vibration analysis information to the user is changeable by the user's input, and the torsional vibration analysis information by the control unit 8 is linked accordingly Is changed.

According to another embodiment of the present invention, the control unit 8 of the present invention, by continuously supplementing the torsional vibration analysis information measured and analyzed for a predetermined period of time to compensate for the characteristic value of a similar condition within a predetermined deviation And a new torsion monitoring process is performed based on the characteristic value.

According to another embodiment of the present invention, the controller 8 may include communication ports 26 and 27 for connection with an external device, in which case the digital-analog signal converter 45 or the relay circuit 46 is provided. It may also include additionally.

The output data after the comparative analysis, that is, the torsional vibration analysis information processed by the digital signal processing element 42, is a digital signal, so that it must be converted into an analog signal in order to be represented in an external device, for example, a vibrometer, a speedometer, or the like. A transducer 45 is needed. This outputs the amount of torsional vibration, the rotational speed of the shaft system 10, etc. as an electrical analog signal of voltage variation.

The relay circuit 46 compares the torsional vibration signal measured on the basis of the environmental setting value by the digital signal processing element 42 to the user through an external device according to the data, i.e., torsional vibration analysis information. It functions to drive. For example, when the measured torsional vibration amount (torsional vibration signal) exceeds a predetermined alarm generation reference value (environmental setting value), the digital signal processing element 42 generates a drive signal for driving the relay circuit 46. By doing so, the relay circuit 46 switches on the external equipment so that an alarm of the external equipment such as a warning light or a siren is activated or an alarm signal is transmitted to the central signal processing device.

The power supply 47 drives a power source for driving the system, and may select and use a DC / AC power source according to a use condition, and includes a device for protecting from physical and electrical shock.

3 is a front view of an exterior of the panel unit 9 connected to the detection unit 13 of the torsional vibration monitoring system according to an exemplary embodiment of the present invention.

According to another embodiment of the present invention, the panel portion 9 of the present invention, the input switch (20, 21, 22, 23, 24) for the user to adjust and operate the system from the outside, and the control unit A liquid crystal display 16 for displaying the torsional vibration analysis information outputted from (8) to a user, and light emitting display elements 17 and 18 to emit light when an alarm occurs according to the torsional vibration analysis information and to inform the user of the torsional vibration analysis information; 19) characterized by including.

The liquid crystal display 16 displays the adjustment state of the system, the torsional vibration analysis information, the alarm occurrence situation and the cause of the abnormal vibration to the user, and the information is displayed in the form of a graph or text. The light emitting display elements 17, 18, and 19 auxiliaryly display information such as a power supply state and an alarm occurrence state together with the liquid crystal display device 16. The input switches 20, 21, 22, 23, and 24 include general keys used to control the system such as a user entering a configuration value or adjusting a system adjustment state. For example, an arrow key and an confirmation key (ack key), the enter key, the mode key, and the like. The panel unit 9 is located inside the case 71 for supporting and protecting them together with the control unit 8. The case 71 includes a terminal block for inputting and outputting signals to and from the detector 13 and external equipment. do.

Hereinafter, the operation of the torsional vibration monitoring system according to an embodiment of the present invention will be described according to three modes (operation mode, setting mode, transmission mode).

1) operation mode

When power is supplied to the installed torsional vibration monitoring system, the power light emitting display device 17 lights up, and the liquid crystal display device 16 sequentially shows the manufacturer's brand, the class of the algorithm, and the adjustment status of the important system, and then the operation standby state. There is.

At this time, if the axis system device 10 is started and a signal is detected by the detection unit 13, and the rotation speed of the shaft reaches a predetermined speed or is rotating within the operating area, the system is in a normal operation state and the liquid crystal display device 16 ) Displays basic information such as the current torsional vibration amount, alarm generation set value and rotational speed together with the speed graph, and keeps only the power light emitting display element 17 lit.

When the amount of torsional vibration changes or the rotational speed changes in the normal operation state, the contents of the liquid crystal display 16 are changed and displayed. When the amount of torsional vibration exceeds the alarm generation setting value, an alarm indication is immediately displayed on the liquid crystal display 16. Blinks, and at the same time, the vibration warning alarm light emitting display element 18 lights up.

At this time, if the amount of torsional vibration decreases within the time delay setting value and remains within the alarm generation setting value, the alarm state is released and the liquid crystal display device 16 and the vibration warning alarm light emitting display element 18 maintain normal operation conditions. The relay circuit 46 does not work. However, if alarm alarm status persists above the time delay setting value, the alarm relay circuit 46 operates to send an alarm to the driver. In this situation, the driver recognizes the alarm condition and sets the ack input switch 24. Until it is pressed, the alarm relay circuit 46 remains in operation regardless of whether the amount of vibration is reduced.

In addition, when the ignition failure of some cylinders occurs in the shaft-type device 10 including a diesel engine, the torsional vibration monitoring system detects this and detects an alarm display on the liquid crystal display 16 and at the same time, a misfire alarm light emitting display element. (19) lights up, and the alarm occurrence / release condition is the same as the above-mentioned vibration amount exceeding alarm occurrence.

If the user wants to change the graph of the liquid crystal display device 16 in the normal operation state, press the up input switch or the down input switch (21, 22) to select one of the speed, time, and count graphs, and the enter input switch (23). When is pressed, the selected graph and information are displayed on the liquid crystal display device 16, and the alarm occurrence / release conditions are the same as those of the speed graph.

2) setting mode

This mode is used when the user wants to change the setting value of the torsional vibration monitoring system. When the mode input switch 20 is pressed, a password input window appears on the liquid crystal display 16, and when the correct password is input, the enter input switch 23 is pressed to display a mode selection screen. Here, after selecting the setting using the up / down input switches 21 and 22 and pressing the enter input switch 23, the setting mode is entered. In the same way, the up / down and enter input switches 23 are used to display the lower window. The setting value can be changed. After completing the change, press the enter input switch 23 to return to the operation mode and the setting process is completed. The system then operates based on the changed setting value.

According to an embodiment of the present invention, the control unit 8 continuously compensates the torsional vibration analysis information measured and analyzed for a predetermined period of time to obtain characteristic values of similar conditions within a predetermined deviation, and calculates the characteristic values. As a standard, a new torsion monitoring process is performed. Here, the characteristic values are measured by test operation of the shaft system device for various values representing mechanical properties of the components of the shaft system device 10 specified, for example, damping coefficient, elastic modulus, inertial mass, and the like, to generate torsional vibration analysis information. The environment setting value.

Therefore, in such a setting mode, when there is no system analysis result for the shaft system device 10 or when it is difficult to set the alarm occurrence reference value due to the deviation of the analysis result and the measurement result, the reference value can be set by self-learning in the present system. This means that if a predetermined amount of torsional vibration occurs during operation for a predetermined period of time, e. It operates by the same algorithm as setting to the occurrence reference value. This function is a useful function that can be used regardless of the system analysis of the shafting device 10, since the set value is determined based on the torsional vibration signal actually generated by the shafting device 10 to be monitored. Extend the scope of application

3) transmission mode

The transmission mode is used when a user or a torsional vibration monitoring system operator transmits the system setting contents and vibration signals to an external computer or an external device such as a printing press using the system.

When the mode input switch 20 is pressed, a password input window appears on the liquid crystal display 16, and after the correct password is input, when the enter input switch 23 is pressed, a mode selection screen is displayed. Here, select the transmission mode by using the up / down input switches 21 and 22 and press the enter input switch 23 to enter the transmission mode, and in the same manner, the setting value using the up / down and enter input switches 23. You can check and change it. After the change is completed, press the enter input switch 23 to display a screen asking whether to transmit, and select 'Yes' and press the enter input switch 23 to start data transmission. At this time, the liquid crystal display 16 displays 'data transmission', and when the transmission is completed, 'transmission success' is displayed. Pressing the enter input switch 23 in this state returns to the operation mode.

The above-described embodiments are only intended to specifically illustrate the present invention, and the spirit of the present invention is not limited only to these embodiments. Therefore, it can be seen that all simple modifications or changes of the present invention belong to the scope of the idea of the present invention.

As described above, according to the present invention, the torsional vibration generated in the shaft system device 10 is easily and continuously monitored, and when abnormal vibration occurs, the driver provides a torsional vibration analysis information for this to establish a prompt countermeasure. Do it.

In addition, according to the present invention, a wide selection range of the detection unit 13 makes it easy to measure the torsional vibration, and when the function of the related functional parts of the shaft system device 10 is degraded by continuous protection monitoring, accidents are taken as a precaution. It is possible to prevent the alarm, even if the system analysis of the shafting device 10 is not possible, it is possible to set the alarm occurrence reference value, and to accumulate trend analysis data for the introduction of a preventive maintenance system. This can prevent economic losses and increase the operating rate of the monitored equipment.

In addition, according to the present invention, since the function is performed according to the programmed algorithm, the function can be easily extended by modifying the program according to the characteristics of the equipment to be monitored, thereby increasing the applicability.

Claims (10)

A torsional vibration monitoring system that monitors and analyzes the state of torsional vibration during operation of the power transmission shaft system and provides the torsional vibration analysis information to the driver. A detection unit (13) attached to the shaft system device (10) for detecting torsional vibration generated in the shaft system device (10) and outputting an electrical signal corresponding thereto; A controller (8) for generating torsional vibration analysis information by comparing and evaluating the electrical signal generated by the detector (13) based on a predetermined set value; And And a panel unit 9 for displaying the torsional vibration analysis information generated by the controller 8 to a user. Here, the control unit 8, A signal adjuster (40) for removing noise from the signal output from the detector (13) to extract a valid signal, and electrically separating the detector (13) from the controller (8); A digital signal processing element (42) for comparing and analyzing the valid signal from the signal conditioner (40) based on a predetermined set value according to a programmed algorithm; A data memory (43, 44) for storing said valid signal, said set value or comparative analysis data thereby and supplying it to said digital signal processing element (42) as needed; A program logic element (41) for controlling the signal regulator (40), the digital signal processing element (42), the data memories (43, 44), etc. and controlling the input / output of the system; And Torsional vibration monitoring system, characterized in that it comprises a power supply (47) for supplying power in the form of direct current, alternating current, or both direct current and alternating current according to the situation of the control unit (8). The torsional vibration monitoring system according to claim 1, wherein the electrical signal output from the detection unit (13) is a pulse wave, and the torsional vibration is expressed as a change in pulse interval in the pulse wave. The method of claim 2, wherein the detection unit 13, A disk-shaped vibration gear 11 having a plurality of protrusions or slits arranged at equal intervals and a vibration detector 14 for generating an electrical signal in the form of a pulse in response to the protrusion or slit when the vibration gear 11 is rotated. Torsional vibration monitoring system comprising a. The method of claim 2, wherein the detection unit 13, A disk-shaped phase tooth 12 having one protrusion or slit and a phase detector 15 for generating an electrical signal in the form of a pulse in response to the protrusion or slit when the phase tooth 12 is rotated. Torsional vibration monitoring system. The method according to claim 1 or 2, wherein the control unit 8, Characterized in that it further comprises a communication port (26, 27) for connecting to an external equipment, and a digital-to-analog signal converter (45) for converting the torsional vibration analysis information into a signal form recognizable by the external equipment, Torsional Vibration Monitoring System. The method according to claim 1 or 2, wherein the control unit 8, Torsional vibration monitoring system, characterized in that it further comprises a communication port (26,27) for connecting to the external equipment, and a relay circuit 46 for performing a contact output to the external equipment according to the torsional vibration analysis information . The method of claim 6, wherein the external equipment, Torsional vibration detection system, characterized in that the siren to generate a visual, audio warning signal. The method according to claim 1 or 2, wherein the control unit 8, The torsional vibration analysis information measured and analyzed is continuously supplemented for a predetermined period of time to obtain characteristic values of similar conditions within a predetermined deviation, and a new torsion monitoring process is performed based on the characteristic values. Vibration monitoring system. The torsional vibration monitoring according to claim 1 or 2, wherein the set value is changeable by a user input, and the torsional vibration analysis information by the control unit 8 is changed accordingly. system. The panel unit 9 according to claim 1 or 2, An input switch (20, 21, 22, 23, 24) for externally controlling and operating the system by a user; A liquid crystal display (16) for displaying the torsional vibration analysis information output from the control unit (8) to a user; And And a light emitting display element (17, 18, 19) which emits light when an alarm occurs according to the torsional vibration analysis information and informs the user of the torsional vibration analysis information.