JP2006262679A - Device diagnosing apparatus, device diagnosing system, and device diagnosing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device diagnosing apparatus for diagnosing a device in detail without attaching a sensor to the device, a device diagnosing system with the device diagnosing apparatus and a device diagnosing method. <P>SOLUTION: If a power supply interrupting signal is acquired through an input section 13, a timing section 14 begins to count a remaining time of a remaining voltage. A voltage detecting section 11 detects the remaining voltage. A voltage comparing section 12 compares the detected remaining voltage with a threshold voltage VH1. If the remaining voltage is smaller than the threshold voltage VH1, a calculating section 15 acquires the remaining time from the timing section 14. If the counted remaining time is within a range between the thresholds TH1, TH2 (TH1<TH2), a diagnosis signal for indicating a normality of the device 5 is outputted. If the remaining time is out of the range between the thresholds TH1, TH2, the diagnosis signal for indicating an abnormality of the device 5 is outputted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a device diagnosis apparatus that diagnoses a device having a rotating body driven by an AC motor, a device diagnosis system including the device diagnosis device, and a device diagnosis method.

  For abnormality diagnosis or preventive maintenance of industrial equipment with rotating bodies driven by AC motors such as blowers, air conditioners, pumps, air compressors, etc., sensors according to the purpose are attached to these equipments. The device is diagnosed based on the detected signal.

  For example, when a transient state during operation / stop of a compressor, etc. is logically determined using signals from sensors that monitor the operation state of a lubricant pump, compressor, etc. In addition, a preventive maintenance method has been proposed in which pre-maintenance is possible by detecting this as an abnormality and displaying the reason for the abnormality on the display unit, thereby preventing sudden stoppage of a compressor or the like (see Patent Document 1).

Also, as a method of diagnosing a pump failure without attaching a sensor such as a flow meter or pressure gauge, the current value of the AC motor when the pump is operating at a constant rotational speed is monitored, and this current value is A diagnostic method for outputting a failure alarm when a set lower limit is exceeded has been proposed (see Patent Document 2).
JP 2000-205140 A JP-A-8-75617

  However, in the example of Patent Document 1, a pressure sensor that detects the pressure of lubricating oil from the pump, an ammeter that detects the drive current of an AC motor that drives the compressor, and a pressure that detects the discharge pressure of the compressor Many sensors are required, such as a meter and a wattmeter that detects the power consumption of the compressor. For this reason, there has been a problem that the mounting work of the sensor is required, and the equipment cost required for the sensor and the labor cost required for sensor maintenance are increased.

  Moreover, in the example of patent document 2, the fall of pump discharge amount is diagnosed as a pump failure by determining whether or not the current value of the AC motor exceeds a preset lower limit value. Yes, it is impossible to diagnose whether the decrease in pump discharge amount is due to the decrease in pump operation efficiency including the efficiency of AC motor or the loss of the rotating body inside the pump. Could not be diagnosed in detail.

  The present invention has been made in view of such circumstances, and detects a residual voltage generated by inertial energy of a rotating body driven by an AC motor, and diagnoses the device according to the length of the remaining time of the detected residual voltage. A device diagnostic apparatus capable of diagnosing a device in more detail than before by attaching a sensor to the device without outputting a sensor to the device, a device diagnostic system and a device diagnostic method including the device diagnostic device The purpose is to provide.

  Another object of the present invention is to output a diagnostic signal indicating an abnormality of a device depending on whether or not the detected remaining time is within a predetermined range, so that a sensor is not attached to the device. Another object of the present invention is to provide a device diagnostic apparatus capable of making a diagnosis according to a device, and a device diagnostic system including the device diagnostic apparatus.

  Another object of the present invention is to output a prohibition signal for prohibiting activation of the device when the residual voltage is higher than the threshold voltage, so that the device can be operated when the AC motor is not stationary. An object of the present invention is to provide a device diagnostic apparatus capable of preventing the device from being damaged by being activated, and a device diagnostic system including the device diagnostic apparatus.

  Another object of the present invention is to output a diagnostic signal indicating an abnormality of the device based on the remaining time measured during the no-load operation and the load operation of the device. It is an object of the present invention to provide a device diagnosis apparatus capable of diagnosing a device and a device diagnosis system including the device diagnosis apparatus.

  Another object of the present invention is to output a diagnostic signal indicating an abnormality of the device based on the interval at which the instantaneous value of the residual voltage intersects with a substantially zero voltage, so that the device is loaded or unloaded. It is an object of the present invention to provide a device diagnosis apparatus capable of diagnosing the operation efficiency of a device without acquiring load information indicating whether or not the device is operating, and a device diagnosis system including the device diagnosis device.

  Another object of the present invention is to store voltage information related to the residual voltage and output the stored voltage information, so that the voltage of the device can be determined based on the residual voltage of the device (for example, a voltage waveform). An object of the present invention is to provide an apparatus diagnosis apparatus capable of facilitating diagnosis and an apparatus diagnosis system provided with the apparatus diagnosis apparatus.

  Another object of the present invention is to provide a device diagnostic apparatus capable of prompting maintenance of a device by outputting a diagnostic signal according to the detection frequency of the residual voltage detected within a predetermined time, An object of the present invention is to provide an apparatus diagnosis system including an apparatus diagnosis apparatus.

  An apparatus diagnosis apparatus according to a first aspect of the present invention is an apparatus diagnosis apparatus for diagnosing an apparatus having a rotating body driven by an AC motor. When the power supplied to the AC motor is cut off, the rotation of the rotating body causes the rotation of the rotating body. Voltage detection means for detecting a residual voltage generated in the AC motor, voltage comparison means for comparing the detected residual voltage with a threshold voltage, and a time at which the residual voltage becomes smaller than the threshold voltage from the time of occurrence of the residual voltage A remaining time measuring means for measuring the remaining time until and a outputting means for outputting a diagnostic signal of the device according to the length of the remaining time.

  The device diagnosis apparatus according to a second aspect of the present invention includes, in the first aspect, a storage unit that stores a first threshold value and a second threshold value greater than the first threshold value, and the remaining time is shorter than the first threshold value, or When longer than a 2nd threshold value, the diagnostic signal which shows the abnormality of the said apparatus is output, It is characterized by the above-mentioned.

  According to a third aspect of the present invention, in the first or second aspect, when the residual voltage is higher than the threshold voltage, the output means outputs a prohibition signal for prohibiting activation of the device. It is characterized by being.

  A device diagnosis apparatus according to a fourth aspect of the present invention is the device diagnosis apparatus according to the third aspect, further comprising: a cut-off signal acquisition unit that acquires a cut-off signal that cuts off the electric power supplied to the AC motor. Is characterized in that a prohibition signal for prohibiting activation of the device is output.

  A device diagnosis apparatus according to a fifth aspect of the present invention is the device diagnosis device according to any one of the second to fourth aspects of the present invention, further comprising load information acquisition means for acquiring load information indicating the load or no load of the device, And the remaining time measured during load operation and a third threshold value are further stored, and the output means subtracts the latest remaining time measured during load operation from the latest remaining time measured during no-load operation. When the measured time is longer than the third threshold value, a diagnostic signal indicating abnormality of the device is output.

  The device diagnosis apparatus according to a sixth aspect of the present invention is the device diagnosis apparatus according to any one of the second to fifth aspects, further comprising zero-crossing timing means for timing an interval at which the instantaneous value of the residual voltage intersects with a substantially zero voltage. A fifth threshold value is further stored, and the output means detects the abnormality of the device when the time from the generation time of the residual voltage to the time point when the interval exceeds the fourth threshold value is longer than the fifth threshold value. The diagnostic signal shown is output.

  According to a seventh aspect of the present invention, in any one of the second to sixth aspects, the device diagnostic apparatus further stores voltage information related to the residual voltage, and the output means outputs the stored voltage information. It is characterized by the above.

  According to an eighth aspect of the present invention, there is provided the device diagnosis apparatus according to any one of the second to seventh aspects, wherein the residual voltage detection time and the number of detection times are further stored, and the output means is a residual within a predetermined time. A diagnostic signal of the device is output according to the voltage detection frequency.

  A device diagnosis system according to a ninth aspect includes a device having a rotating body driven by an AC motor and the device diagnosis apparatus according to any one of the first to eighth aspects.

  A device diagnosis method according to a tenth aspect of the present invention is the device diagnosis method for diagnosing a device having a rotating body driven by an AC motor, wherein when the power supplied to the AC motor is cut off, the rotation body rotates to rotate the rotating body. The residual voltage generated in the AC motor is detected, the detected residual voltage is compared with the threshold voltage, and the remaining time from the time when the residual voltage is generated to the time when the residual voltage becomes smaller than the threshold voltage is counted. A diagnostic signal of the device is output according to the length of the remaining time.

  In the first invention and the tenth invention, when the AC motor is stopped by cutting off the electric power supplied to the AC motor, the AC is driven by the inertial energy of the rotating body driven by the AC motor. The rotating shaft of the motor continues to rotate together with the rotating body, and the AC motor acts as a generator, and a residual voltage that changes alternately is generated on the input side of the AC motor. The inertial energy includes work energy (equivalent to the operation efficiency of the device) that acts on fluid (air, water, etc.) that is a load loss of the device (for example, a blower, an air conditioner, a pump, and an air compressor) and no load on the device. It is consumed by loss (for example, bearing friction loss, shaft seal friction loss, etc.). The residual voltage is detected by the voltage detection means, and the detected residual voltage and the threshold voltage are compared by the voltage comparison means. The remaining time measuring means measures the remaining time from the time when the power supply is shut off (when the residual voltage is generated) to the time when the residual voltage is smaller than the threshold voltage. Depending on the load loss or no-load loss of the equipment, the consumption of inertial energy changes and the remaining time also changes. In other words, the remaining time changes depending on the presence or absence of equipment aging (decrease in equipment efficiency) and abnormalities (bearing, shaft seal failure, impeller contact due to shaft flatness, increased friction loss due to foreign object biting, etc.) To do. The output means outputs a diagnostic signal of the device according to the length of the time remaining.

  In the second invention, when the remaining time is shorter than the first threshold or longer than the second threshold larger than the first threshold, a diagnostic signal indicating an abnormality of the device is output. If the remaining time is not less than the first threshold and not more than the second threshold, the device is diagnosed as normal. When the remaining time is shorter than the first threshold value, for example, it is determined that the friction loss has increased due to wear of a bearing such as an air conditioner or an air compressor, and a diagnostic signal indicating an abnormality of the device is output. If the remaining time is longer than the second threshold value, for example, it is determined that a foreign matter has adhered to an impeller such as a blower or a pump and the moment of inertia has increased, and a diagnostic signal indicating an abnormality of the device is output.

  In the third invention, when there is a residual voltage higher than the threshold voltage, a prohibition signal for prohibiting the activation of the device is output. If the rotation of the AC motor stops after the AC motor is turned off, the residual voltage becomes zero. However, for example, when air or water flows backward from a discharge port of a device such as a pump or a blower due to a failure of the device, or when an exhaust fan is provided by operating the intake fan of the air conditioner alone, the AC motor power is turned off. When switching from a commercial power supply to an inverter device, there is a residual voltage, and driving the equipment may cause an inrush current to flow through the equipment and damage the equipment. By outputting a prohibition signal, the device is prevented from starting while there is a residual voltage.

  In the fourth aspect of the invention, when a shut-off signal for shutting off the power supplied to the AC motor is obtained, if a residual voltage higher than the threshold voltage exists, a prohibit signal for prohibiting the start of the device is output. To do. By outputting a prohibition signal, the device is prevented from starting while there is a residual voltage.

  In the fifth invention, the load information acquisition means acquires the load information indicating the no-load state or the load state of the device. The remaining time counting means measures the remaining time when the device is shut off during no-load operation and when it is shut off during load operation according to the acquired load information, and stores the measured remaining time. To do. For example, a discharge gate valve or a damper is attached to a blower, a pump, etc., and when these are opened (during load operation), inertial energy is a fluid (air) that is a load loss of equipment such as a blower, a pump, etc. , Water, etc.) and the total load loss that is the sum of the no-load loss (eg, bearing friction loss, shaft seal friction loss, etc.) of the equipment. On the other hand, when the discharge gate valve or damper is closed (during no-load operation), air, water, etc. do not flow, so inertial energy is no-load loss of equipment (for example, bearing friction loss, shaft seal friction loss, etc. ) Only consumed. As a result of comparing the time obtained by subtracting the latest remaining time measured during load operation from the latest remaining time measured during no-load operation with the third threshold, if the time is longer than the third threshold, the rotation of the device It is determined that the operating efficiency of the device is reduced because the consumption of inertial energy of the body is small and the work energy consumed by the fluid is reduced.

  In the sixth aspect of the invention, the interval at which the instantaneous value of the alternating voltage that changes alternately intersects the substantially zero voltage is measured, and the measured interval is compared with the fourth threshold value. When the time from when the residual voltage occurs to the time when the interval exceeds the fourth threshold is longer than the fifth threshold, a diagnostic signal indicating an abnormality of the device is output. The air compressor sends compressed air to the oil separator tank to separate the oil from the compressed air, and the compressed air separated from the oil is sent to the compressed air chamber via a check valve provided at the discharge port of the oil separator tank. send. When the air compressor is stopped (corresponding to the time when the residual voltage is generated), the check valve is closed because the air pressure decreases. After the air compressor is stopped, until the check valve is closed, inertial energy is consumed due to work energy acting on the air and no-load loss due to the inside of the air compressor device. When the check valve is closed, a reverse pressure is transiently applied in the oil separator tank, the reverse pressure acts on the rotating body of the air compressor, and a large amount of inertia energy is consumed. For this reason, the interval at which the instantaneous value of the residual voltage intersects with a substantially zero voltage increases. When the reverse pressure is consumed by inertial energy, the reverse pressure disappears and the inertial energy is consumed only by the no-load loss of the air compressor. That is, when there is no change in the remaining time of the residual voltage and the time from when the residual voltage is generated to when the interval exceeds the fourth threshold value, the degree of consumption of inertial energy of the rotating body of the device is small, and the air It is determined that the operating efficiency of the device is reduced, such as being hard to be consumed by the working energy, that is, clogging of the filter of the air intake port of the air compressor.

  In the seventh invention, voltage information relating to the residual voltage is stored, and the stored voltage information is output as, for example, a voltage waveform.

  In the eighth invention, the number of times of detection of the residual voltage is stored, and a diagnostic signal for the device is output according to the frequency of detection of the residual voltage within a predetermined time.

  In the ninth invention, the apparatus includes a device having a rotating body driven by an AC motor, and the device diagnostic apparatus according to any one of the first to eighth inventions.

  In the first invention, the ninth invention, and the tenth invention, the inertial energy of the rotating body driven by the AC motor when the power supplied to the input side of the AC motor is shut off and the AC motor is stopped. By detecting the residual voltage generated by, and outputting the diagnostic signal of the device according to the length of the remaining time until the detected residual voltage becomes lower than the threshold voltage, the sensor is not attached to the device and compared with the conventional one. The device can be diagnosed in detail.

  In the second and ninth inventions, the sensor is attached to the device by comparing the detected remaining time with a threshold value and outputting a diagnostic signal indicating the device abnormality according to the comparison result. In addition, diagnosis according to the device can be performed.

  In the third invention, the fourth invention, and the ninth invention, when the residual voltage is higher than the threshold voltage, by outputting a prohibition signal for prohibiting the activation of the device, when the AC motor is not stationary, the device By starting up, it is possible to prevent an inrush current from flowing and damaging the device.

  In the fifth and ninth inventions, a diagnostic signal indicating an abnormality of the device is output based on a difference between the remaining time measured during the no-load operation of the device and the remaining time measured during the load operation. By doing so, the operation efficiency of the device can be diagnosed.

  In the sixth and ninth aspects of the invention, the interval at which the instantaneous value of the residual voltage crosses the substantially zero voltage is measured, and the time from the occurrence of the residual voltage to the time when the interval exceeds the fourth threshold is When it is longer than 5 thresholds, it is possible to diagnose the operation efficiency of the device without acquiring load information indicating whether the device is operating with a load or no load by outputting a diagnosis signal indicating the abnormality of the device. it can.

  In the seventh and ninth aspects of the invention, voltage information relating to the residual voltage is stored, and the stored voltage information is output, so that the diagnosis of the device is performed based on the residual voltage of the device (for example, a voltage waveform). Can be easily.

  In the eighth and ninth inventions, maintenance of the device can be promoted by outputting a diagnostic signal in accordance with the frequency of detection of the residual voltage within a predetermined time.

Embodiment 1
Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof. FIG. 1 is a block diagram showing a configuration of a device diagnostic apparatus 1 according to the present invention. In the figure, reference numeral 2 denotes a three-phase AC commercial power source. A device 5 (for example, a blower, an air conditioner, a pump, an air compressor, a crane, or the like) is connected to the commercial power source 2 via a power line 3, and the power line 3 is connected to the middle of the power line 3. A power breaker 4 for opening and closing is provided. By controlling the power breaker 4, the power supplied to the device 5 is turned on and off. The device 5 includes an induction motor 51, a rotating body 53 such as a fan or an impeller, and a drive belt 52 is attached to the rotation shaft of the induction motor 51. The rotation of the rotation shaft of the induction motor 51 is changed to the drive belt 52. To the rotating body 53.

  A voltage detection line 6 for detecting a voltage between two phases is connected to the power supply line 3 between the power breaker 4 and the device 5, and the voltage detection line 6 is connected to the device diagnostic apparatus 1. is there. In addition, a control line 41 for transmitting a power cutoff signal indicating the open / close state of the power breaker 4 is connected to the device diagnostic apparatus 1. Thereby, the device diagnostic apparatus 1 acquires the open / close state of the power breaker 4.

  When the power circuit breaker 4 is opened and the commercial power source 2 is disconnected from the device 5 for the device 5 in the operating state, the device 5 shifts from the operating state to the stopped state, but the rotation shaft of the induction motor 51 rotates. The rotor of the induction motor 51 continues to rotate due to the inertial energy of the rotating body 53 that rotates in conjunction with the motor, and the induction motor 51 acts as a generator. Between the power lines 3 connected to the induction motor 51 Residual voltage that changes alternately is generated. As the inertial energy of the rotating body 53 is consumed, the peak value of the residual voltage gradually decreases, and the residual voltage continues to be generated until the rotation of the rotating body 53 stops.

  In the device diagnostic apparatus 1, reference numeral 13 denotes an input unit. When the power breaker 4 is opened, the input unit 13 acquires a power cut-off signal and outputs the acquired power cut-off signal to the calculation unit 15.

  The voltage detection unit 11 detects a residual voltage generated in the power supply line 3 and outputs the detected residual voltage to the voltage comparison unit 12. The voltage comparison unit 12 is realized by an operational amplifier or the like, compares the residual voltage input from the voltage detection unit 11 with a threshold voltage VH1 (for example, 50 mV), and when the residual voltage becomes lower than 50 mV, the residual voltage A residual voltage zero signal indicating zero voltage is output to the calculation unit 15.

  The arithmetic unit 15 is realized by a microprocessor, and outputs a time measurement start signal for starting time measurement to the time measurement unit 14 when a power cut-off signal is acquired from the input unit 13. When the voltage comparison unit 12 outputs a residual voltage zero signal, the calculation unit 15 obtains the time measured by the time measurement unit 14, and thereby the time from when the residual voltage is generated to the time when the residual voltage is less than 50 mV. Get the remaining time, which is time. The calculation unit 15 compares the acquired remaining time with the threshold values (TH1, TH2) stored in advance in the storage unit 16 to output a diagnostic signal indicating an abnormality of the device to the output unit 17. The diagnostic contents are output to the display unit 19.

  The calculation unit 15 acquires voltage information (for example, time and voltage value at the time) of the residual voltage detected by the voltage detection unit 11 via the voltage comparison unit 12, and stores the acquired voltage information in the storage unit 16. Remember. The computing unit 15 stores the detected number of detected residual voltages in the storage unit 16 together with the detection time. In addition, the calculation unit 15 compares the stored detection frequency with a predetermined threshold value CH1, and outputs a diagnostic signal when the detection frequency within a predetermined time exceeds the predetermined threshold value CH1.

  The storage unit 16 stores a device diagnosis database 161 for diagnosing device abnormality. FIG. 2 is an explanatory diagram showing a record layout of the device diagnosis database 161. The device diagnosis database 161 stores device diagnosis contents according to the length of the remaining time for each device type. For example, in the blower, when the remaining time of the residual voltage is 27 to 33 seconds, it is diagnosed that the state of the blower is normal. When the remaining time is shorter than the threshold value TH11 of 27 seconds, it is diagnosed that the state of the blower is abnormal due to bearing wear, and when the remaining time is shorter than the threshold value TH12 of 15 seconds, the state of the blower is due to the drive belt running out. Is diagnosed as abnormal. Further, when the remaining time of the residual voltage is longer than the threshold value TH2, which is 33 seconds, it is diagnosed that the state of the blower is abnormal because foreign matter is attached to the impeller. The same applies to other air conditioners, pumps, compressors and the like. Needless to say, the remaining time is appropriately changed according to the capacity and rating of each device.

  The output unit 17 outputs the diagnosis result (normality, abnormality, etc.) of the device and the diagnosis content (abnormal state of the device) to the outside based on the diagnostic signal input from the calculation unit 15. In addition, the display unit 19 includes a display, and displays the diagnostic result of the device and the diagnostic content on the display based on the diagnostic signal input from the calculation unit 15.

  The operation unit 18 includes a keyboard, a mouse, an operation switch, and the like, and the remaining time threshold values (TH1, TH2) stored in the device diagnosis database 161, diagnosis contents, and the like by operations of an administrator who manages device diagnosis, etc. Can be registered, updated, or deleted. In addition, when the diagnostician operates from the operation unit 18, voltage information regarding the residual voltage stored in the storage unit 16 can be read and displayed on the display unit 19 as a voltage waveform. Thereby, the diagnosis of an apparatus can be performed in detail. For example, when a foreign object adheres to the fan, the rotational balance of the fan is not balanced, the symmetry of the residual voltage waveform is broken, and the peak value lowering curve changes. Such an abnormality can be diagnosed by checking the voltage waveform.

  Next, the operation of the device diagnostic apparatus 1 according to the present invention will be described. FIG. 3 is a flowchart showing a processing procedure of the device diagnostic apparatus 1 according to the present invention. When the power breaker 4 is opened and the commercial power supply 2 supplied to the operating device 5 (for example, a blower) is cut off, the impeller of the blower continues to rotate due to inertial energy. For this reason, the rotor of the induction motor 51 continues to rotate, the induction motor 51 acts as a generator, and a residual voltage is generated between the power lines 3 connected to the induction motor 51.

  The device diagnostic apparatus 1 acquires a power shutdown signal (S10), and starts measuring time for measuring the remaining time of the residual voltage (S11). The device diagnostic apparatus 1 detects the residual voltage (S12), and compares the detected residual voltage with the threshold voltage VH1 (S13). If the residual voltage is greater than the threshold voltage VH1 (NO in S13), the device diagnostic apparatus 1 continues the processing from step S12. When the residual voltage is smaller than the threshold voltage VH1 (YES in S13), the device diagnostic apparatus 1 acquires the remaining time (S14). The device diagnosis apparatus 1 compares the remaining time with a predetermined threshold (TH1, TH2) (S15), and when the remaining time is within the range between the threshold TH1 and the threshold TH2 (TH1 <TH2) (YES in S15). The device diagnostic apparatus 1 outputs a diagnostic signal indicating that the device 5 is normal (S16), and ends the process. On the other hand, when the remaining time is not within the range between the threshold TH1 and the threshold TH2 (TH1 <TH2) (NO in S15), the device diagnostic apparatus 1 outputs a diagnostic signal indicating that the device 5 is abnormal (S17). The process is terminated.

  The failure of the blower is a drive belt shortage, abnormal vibration or abnormal noise due to bearing wear, foreign matter adhering to the impeller, and the like. When there is no abnormality in the blower, the inertial energy of the impeller (rotating body 53) is consumed by work energy acting on the air, which is a load loss of the blower, and no load loss of the blower (for example, a bearing friction loss). In time, the generated residual voltage disappears.

  However, when there is an abnormality in the blower, for example, when the degree of bearing wear is large and maintenance is required, the frictional loss of the bearing increases, so the inertia energy of the impeller is normal for the blower. It is consumed earlier than in some cases, and the remaining time from the time when the residual voltage occurs until the time when the residual voltage disappears becomes shorter.

  Further, since the inertia moment of the impeller of the blower is larger than the inertia moment of the rotating shaft of the induction motor 51, when the drive belt is cut, the inertia energy of the impeller is not transmitted to the induction motor 51, and the rotation of the induction motor 51 is performed. The rotation of the shaft stops in a short time compared to the case where the blower is normal.

  Further, when foreign matter adheres to the impeller of the blower, the inertial energy of the impeller increases due to the presence of the foreign matter, and the remaining time of the residual voltage becomes longer than when the blower is normal.

  FIG. 4 is a time chart showing an example of the residual voltage. For example, when the commercial power supplied to the blower with the rated voltage of 200 V is cut off at time t = 0, a residual voltage is generated almost simultaneously with the cut-off, and as shown in FIG. At time t = t1, the residual voltage disappears. In this case, the remaining time is t1.

  As shown in FIG. 4B, when the degree of bearing wear of the blower is large and the blower is abnormal, the remaining time is t2 (t2 <t1). Moreover, as shown in FIG.4 (c), when a foreign material adheres to the impeller of an air blower, remaining time will be t3 (t3> t1).

  Therefore, by detecting the remaining time of the residual voltage and comparing it with predetermined thresholds TH1 and TH2, it is possible to make a detailed diagnosis of the presence / absence of the fan and the details of the abnormality.

  The devices that can be diagnosed are not limited to the blower, and other devices can diagnose the presence / absence of abnormality and the details of the abnormality. For example, in the case of a compact air conditioner in which a heat exchanger and a fan are integrated, the fan is directly connected to the rotating shaft of the induction motor, and a drive belt is not necessary. In addition, since such an air conditioner is used in a relatively clean usage environment, dust or the like rarely accumulates on the fan, the moment of inertia of the fan is not easily changed, and the fan efficiency is hardly reduced. Air conditioner abnormalities are mainly due to bearing wear. Therefore, by detecting a change in the remaining time of the residual voltage, it is possible to diagnose whether there is an abnormality in the air conditioner.

  In the case of submersible pumps, special carbon thrust bearings are used for bearings such as freshwater submersible pumps. However, the impeller and liner ring come into contact with each other due to wear of the bearings, and the rotational torque of the impeller increases. There are many failures that fall into the load operating state. In this case, inertial energy is consumed by the increased rotational torque, and the remaining time of the residual voltage is shortened as compared with the case where the pump is normal.

  Also, in the sewage / dirt pump, if a large foreign object is sucked in, the foreign object gets caught between the impeller and the casing, the pump enters a restrained state, an overcurrent flows through the induction motor, and the pump operation stops. There is a time. However, in this case, it is difficult to determine whether the stoppage of the pump is abnormal due to pump restraint or an overcurrent due to an increase in load. In the case of pump restraint due to foreign object biting, no residual voltage is generated. Therefore, if the remaining time of the residual voltage is approximately 0 seconds when the power shut-off signal is acquired, the pump abnormality is Can be diagnosed.

  Further, when foreign matter such as a piece of cloth adheres to the impeller of the pump, inertial energy increases due to the attached foreign matter, and the remaining time becomes longer than normal as in the case of the blower. Therefore, by detecting a change in the remaining time of the residual voltage, it is possible to diagnose whether there is an abnormality in the pump.

  In the case of an air compressor, there are malfunctions such as abnormal vibration or abnormal noise due to bearing wear, running out of the drive belt, and the like. When there is an abnormality in the air compressor, for example, when the degree of bearing wear is large, the bearing friction loss increases, so the inertia energy of the rotor is consumed earlier than when the air compressor is normal, The remaining time from the time when the residual voltage occurs until the time when the residual voltage disappears becomes shorter.

  In addition, since the rotational torque of the rotor of the air compressor is larger than that of the induction motor, the inertia energy is not consumed by the rotational torque of the rotor when the drive belt is broken, and the remaining time of the residual voltage is Longer than when the machine is normal. Therefore, by detecting a change in the remaining time of the residual voltage, it is possible to diagnose the presence or absence of an abnormality in the air compressor.

  In the case of a hoist used for cargo handling, if the number of starts exceeds the specified frequency, it is necessary to replace consumable parts such as brakes, electromagnetic switches, and wire ropes. By comparing the cumulative value of the number of times of detection with a predetermined threshold value CH1, it is possible to diagnose the time for replacement of consumables.

  Moreover, when stopping the hoist in driving | running | working, stop time becomes long by abrasion of a brake. Since the residual voltage is generated until the hoist completely stops, it is possible to diagnose the hoist brake abnormality by judging the length of the residual time.

  In the above-described embodiment, the remaining time is compared with the threshold value, and the diagnostic signal of the device is output according to the length of the remaining time. However, the output diagnostic signal is particularly limited. Instead, it can be changed according to the type of device to be diagnosed. For example, a threshold value to be compared with the remaining time can be set in a plurality of stages, and the degree of abnormality can be notified in stages according to the comparison result with the threshold value set in stages. That is, in order to avoid a sudden shutdown due to an abnormality, it may be configured to output a forecast signal that prompts preventive maintenance, a warning signal that informs that the life of the device is approaching, an abnormal signal that requires an emergency, etc. .

  In the above-described embodiment, the time point when the power shut-off signal is acquired is set as the time point when the residual voltage is generated. However, the present invention is not limited to this. For example, instead of acquiring the power shutoff signal, the voltage supplied to the induction motor is detected by the device diagnostic apparatus 1, and when the voltage drops to a predetermined voltage, for example, when the voltage drops from 200V to 50V, the residual voltage It can also be set as the time of occurrence.

  In the above-described embodiment, the threshold voltage to be compared with the residual voltage is 50 mV. However, the threshold voltage is not limited to this, and is appropriately changed according to the type and rating of the device used. be able to. For example, values such as 100 mV and 200 mV may be used.

  In the above-described embodiment, when the power-off signal is acquired, it is determined whether or not the remaining time of the residual voltage is approximately 0 seconds, and the pump abnormality due to foreign object biting is diagnosed. However, the present invention is not limited to this, and a hoist lock can be diagnosed. That is, when a brake lock is generated by using an inching while using a hoist, this can be diagnosed to prevent motor burnout.

Embodiment 2
By acquiring the load state of the device, the device can be diagnosed in more detail. FIG. 5 is a block diagram illustrating a configuration of the device diagnosis apparatus 1 according to the second embodiment. A difference from the first embodiment is that a valve opening / closing signal indicating a load state of the device is acquired from the device 5 (for example, a blower, a pump, etc.).

  In the figure, 54 is a damper or a gate valve. The device 5 outputs a valve opening / closing signal indicating the opening / closing state of the damper or the gate valve to the input unit 13 of the device diagnostic apparatus 1 via the signal line 55. The input unit 13 outputs the valve opening / closing signal input from the device 5 to the calculation unit 15. Thereby, the calculating part 15 can acquire the load state of the apparatus 5. In addition, the same part as Embodiment 1 attaches | subjects the same code | symbol, and abbreviate | omits description.

  When the damper or gate valve of the device 5 is open, air or water can flow through the flow path of the device 5, and inertial energy is a fluid (air, water, etc.) that is a load loss of the device 5 such as a blower or a pump. ) And the total load loss that is the sum of the no-load loss (for example, bearing friction loss, shaft seal friction loss, etc.) of the device 5 (during load operation). On the other hand, when the damper or gate valve of the device 5 is closed, air and water do not flow, so inertial energy is consumed only with no-load loss (for example, bearing friction loss, shaft seal friction loss, etc.) of the device 5. (During no-load operation)

  The device diagnostic apparatus 1 obtains a valve opening / closing signal to determine whether the device 5 is in a load state, that is, whether it is in a load operation or a no-load operation, and measures the remaining time of the residual voltage. The load state of the device 5 is also stored in the storage unit 16 together. The device diagnosis apparatus 1 diagnoses a difference in work energy acting on the fluid of the device 5, that is, a decrease in load operation efficiency of the device 5 based on a difference in remaining time between the no-load operation and the load operation of the device 5.

  FIG. 6 is an explanatory diagram showing the change over time in the remaining time during no-load operation and load operation of the device 5. As shown in FIG. 6A, when the device 5 is new (for example, when the device is installed or when maintenance is completed), the remaining time measured when the valve is fully closed (no load operation), and the valve fully opened Let ta be the time difference from the remaining time measured at the time (load operation). As the device 5 is used, the load operation efficiency of the device 5 and the no-load loss inside the device increase. Therefore, as shown in FIG. 6B, the time is measured when the valve is fully closed (during no-load operation). The remaining time is shorter than in the case of a new product, and the remaining time measured when the valve is fully opened (load operation) is also shorter than in the case of a new product. In this case, let tb be the time difference between the remaining time measured when the valve is fully closed (no load operation) and the remaining time measured when the valve is fully opened (load operation).

  The time difference between the remaining time measured when the valve is fully closed (during no load operation) and the remaining time measured when the valve is fully opened (during load operation) is the work energy acting on the fluid of the device 5, that is, the device 5 Therefore, if tb and ta are substantially equal, it can be diagnosed that there is no decrease in load operation efficiency of the device 5, while the difference between the most recently measured tb and ta is When the threshold TH3 stored in the storage unit 16 is exceeded, the degree of inertia energy consumption of the rotating body of the device is small, and the work energy consumed by the fluid is reduced. Can be diagnosed as decreased.

Embodiment 3
The device can be diagnosed in more detail without acquiring the load state of the device. FIG. 7 is a block diagram illustrating a configuration of the device diagnosis apparatus 1 according to the third embodiment. The difference from the first and second embodiments is that the device diagnostic apparatus 1 includes a zero-cross detection unit 10 that detects a zero-cross of a residual voltage (that is, a point in time when an instantaneous value of the residual voltage crosses a substantially zero voltage).

  In the device 5 (for example, an air compressor), 56 is an air suction port, and a filter 57 is attached to the air suction port 56. The air compressed by the rotary body 53 of the air compressor is separated into oil and air in the oil separator tank 58 and sent to the compressed air tank via a check valve 59 attached to the discharge port of the oil separator tank 58. It is.

  When acquiring the power cutoff signal from the input unit 13, the arithmetic unit 15 outputs a zero cross detection start signal for starting detection of the zero cross of the residual voltage to the zero cross detection unit 10. When the zero-cross detection start signal is input from the calculation unit 15, the zero-cross detection unit 10 sends the zero-cross detection signal to the calculation unit 15 every time the instantaneous value of the residual voltage detected by the voltage detection unit 11 crosses substantially zero voltage. Output.

  Whenever the zero cross detection signal is received from the zero cross detection unit 10, the calculation unit 15 acquires the time measured by the time measurement unit 14 and calculates the zero cross interval of the residual voltage. The calculation unit 15 compares the calculated zero-cross interval with the threshold value (TH4) stored in the storage unit 16, and the calculated zero-cross interval exceeds the threshold value (TH4) from the time when the residual voltage is generated. Calculate time to time. When the calculated time is longer than the threshold (TH5) stored in the storage unit 16, the calculation unit 15 outputs a diagnostic signal indicating an abnormality of the device.

  When the air compressor in operation is shut off and stopped, the rotating body 53 continues to rotate due to the inertial energy of the rotating body 53, but the pressure released to the compressed air tank disappears and the check valve 59 is blocked. To do. When the check valve 59 is closed, the reverse pressure acts on the rotating body 53 due to the pressure in the oil separator tank 58, and a large amount of inertia energy is consumed. Thereafter, when the reverse pressure gradually decreases, the effect of the reverse pressure is lost, and inertial energy is consumed due to the no-load loss of the air compressor, and the rotating body 53 stops.

  FIG. 8 is a time chart showing an example of the residual voltage when the air compressor is stopped. FIG. 8A shows the residual voltage at the normal time. At t = 0, the power supply is cut off and a residual voltage is generated. Until the check valve 59 is closed, the inertial energy of the rotating body 53 is the total load that is the sum of the work energy acting on the air that is the load loss and the no-load loss (for example, bearing friction loss) of the air compressor. It is consumed by loss (during load operation).

When the check valve 59 is closed at t = tC ₁ , the reverse pressure is applied to the rotating body 53 by the pressure in the oil separator tank 58, and the inertia energy is largely consumed, so the waveform of the residual voltage changes. That is, the interval at which the instantaneous value of the residual voltage crosses 0V is increased. In addition, the peak value of the residual voltage decreases.

When t = tC ₂ , the reverse pressure is consumed by inertial energy, and when the reverse pressure disappears, the inertial energy is consumed only by no-load loss (for example, bearing friction loss) of the air compressor (during no-load operation) , T = tC ₃ , the inertial energy is consumed, and the rotation of the rotating body 53 is stopped.

FIG. 8B shows the residual voltage at the time of abnormality. As shown in the figure, time tC ₃ ′ is substantially equal to time tC _3, and when time tC ₁ ′ is longer than tC ₁ , inertial energy is not easily consumed by work energy acting on air, that is, the air compressor Indicates that the load operating efficiency is decreasing.

  Accordingly, the device diagnostic apparatus 1 is configured such that when there is no change in the remaining time of the residual voltage and the time from when the residual voltage occurs until the time when the zero-crossing interval exceeds the threshold (TH4) is longer than the threshold (TH5), the air compressor It is determined that the operating efficiency of the equipment is reduced, such as clogging of the air inlet filter.

In the case of an air compressor, a filter is attached to the air suction port, and a decrease in operating efficiency results in a decrease in discharge air pressure due to filter clogging. As an example, in a 7.5 kW air compressor, the filter intake resistance at the time of cleaning the filter is increased by 200 mmHg, the discharge air amount is reduced by 24%, and the shaft power is reduced by 10% with respect to the normal time. Further, the filter intake resistance at the time of filter replacement has an increase of 500 mmHg, the amount of discharge air is reduced by 35%, and the shaft power is reduced by 23% with respect to the normal time. Since the work energy acting on the air corresponds to the shaft power, if the shaft power is reduced by 10%, the time tC _{1 of the} residual voltage is considered to be increased by 10%.

When one of the four filters at the suction port of a 7.5 kW air compressor is closed (discharged air volume is reduced by approximately 25%) and when it is not closed, the residual voltage is measured. The time tC ₁ when the filter is not used is 2275 ms, whereas the time tC ₁ when one filter is closed is 2500 ms, and the time tC ₁ is increased by about 10%, which is about 10% reduction in shaft power. Match. Therefore, it is possible to diagnose the filter cleaning time, the filter replacement time, and the like according to the magnitude of the residual voltage time tC ₁ .

  In the above embodiment, the device is diagnosed according to the remaining time of the residual voltage. However, the residual voltage is compared with the predetermined threshold value VH1, and the residual voltage is larger than the predetermined threshold value VH1. In this case, a prohibition signal for prohibiting the activation of the device can be output to prevent the activation of the device and protect the device.

  For example, in an apparatus including an induction motor and an inverter device, the power supplied to the induction motor may be switched between a commercial power source and the inverter device in order to perform an energy saving operation. In this case, when switching from the commercial power source to the inverter device, there is a problem that an inrush current flows in the inverter device due to the reverse phase of the residual voltage, and the inverter device is damaged. The device diagnostic apparatus 1 according to the present invention detects the residual voltage, and outputs the prohibition signal so that the switching to the inverter device is not performed while the residual voltage exists, thereby preventing the above-described problem. it can.

  In addition, in an air conditioner equipped with an intake fan and an exhaust fan, only the intake fan may be operated independently during a trial operation after installation or after maintenance, and the exhaust fan may be circulated by the air sent by the intake fan. is there. When the exhaust fan is started in this state, the electric motor starting current flows more than usual, which may cause contact welding of the electromagnetic switch, damage to the power supply equipment, damage to the exhaust fan, and the like. The device diagnostic apparatus 1 according to the present invention detects the residual voltage, and outputs the prohibition signal so that the exhaust fan is not started while the residual voltage exists, thereby preventing the above-described problem. .

  Moreover, the sewage and filth pumps used for manholes adjust the water level in the manholes by alternately operating two pumps. If one of the check valves on the pump side fails due to, for example, clogging of foreign matter, the sewage flows back from the pump side where the check valve is normal to the pump side where the check valve is faulty, even if the pump body is normal. In addition, a sewage tank overflow accident occurs. In such a case, the check valve failure can be diagnosed by the residual voltage generated by the rotation of the pump in which the check valve is broken due to the water sent from the pump having the normal check valve.

  In the above-described embodiment, the device diagnosis apparatus 1 is separate from the device 5, but is not limited to this, and the device diagnosis apparatus 1 of the present invention is built in each device 5. May be. Regardless of whether the device diagnosis apparatus is configured separately from the device or provided inside the device, the device diagnosis system can be configured. Moreover, the structure which diagnoses a some apparatus with the apparatus diagnostic apparatus 1 may be sufficient.

It is a block diagram which shows the structure of the apparatus diagnostic apparatus which concerns on this invention. It is explanatory drawing which shows the record layout of an apparatus diagnosis database. It is a flowchart which shows the process sequence of the apparatus diagnostic apparatus which concerns on this invention. It is a time chart which shows the example of a residual voltage. It is a block diagram which shows the structure of the apparatus diagnostic apparatus in Embodiment 2. FIG. It is explanatory drawing which shows the time-dependent change of the remaining time at the time of a no-load driving | operation of an apparatus, and a load driving | operation. FIG. 10 is a block diagram illustrating a configuration of a device diagnostic apparatus in a third embodiment. It is a time chart which shows the example of the residual voltage at the time of stopping an air compressor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Apparatus diagnostic apparatus 5 Apparatus 51 Induction motor 53 Rotor 10 Zero cross detection part 11 Voltage detection part 12 Voltage comparison part 13 Input part 14 Time measuring part 15 Calculation part 16 Storage part 17 Output part 18 Operation part 19 Display part

Claims (10)

In a device diagnostic apparatus for diagnosing a device having a rotating body driven by an AC motor,
Voltage detecting means for detecting a residual voltage generated in the AC motor due to rotation of the rotating body when power supplied to the AC motor is cut off;
Voltage comparison means for comparing the detected residual voltage with a threshold voltage;
A remaining time measuring means for measuring a remaining time from a time when the residual voltage is generated to a time when the residual voltage is smaller than the threshold voltage;
An apparatus diagnosis apparatus comprising: output means for outputting a diagnosis signal of the apparatus according to the length of the time remaining. Storage means for storing a first threshold value and a second threshold value greater than the first threshold value;
2. The device diagnosis according to claim 1, wherein when the remaining time is shorter than the first threshold or longer than the second threshold, a diagnostic signal indicating an abnormality of the device is output. apparatus. When the residual voltage is higher than the threshold voltage,
The output means includes
3. The apparatus diagnosis apparatus according to claim 1, wherein a prohibition signal for prohibiting activation of the apparatus is output. A cutoff signal acquisition means for acquiring a cutoff signal for cutting off power supplied to the AC motor;
When obtaining the blocking signal,
The output means includes
The apparatus diagnosis apparatus according to claim 3, wherein a prohibition signal for prohibiting activation of the apparatus is output. Load information acquisition means for acquiring load information indicating the load or no load of the device,
The remaining time measured during no-load operation and load operation of the device, and a third threshold value are further stored,
The output means includes
When a time obtained by subtracting the latest remaining time measured during load operation from the latest remaining time measured during no-load operation is longer than the third threshold, a diagnostic signal indicating an abnormality of the device is output. The apparatus diagnosis apparatus according to claim 2, wherein the apparatus diagnosis apparatus is provided. Zero cross timing means for timing the interval at which the instantaneous value of the residual voltage crosses the substantially zero voltage,
A fourth threshold and a fifth threshold are further stored;
The output means includes
A diagnostic signal indicating an abnormality of the device is output when the time from the occurrence of the residual voltage to the time when the interval exceeds the fourth threshold is longer than the fifth threshold. The apparatus diagnostic apparatus in any one of Claims 2 thru | or 5. Voltage information related to the residual voltage is further stored.
The output means includes
7. The apparatus diagnosis apparatus according to claim 2, wherein the stored voltage information is output. The residual voltage detection time and the number of detections are further stored,
The output means includes
8. The apparatus diagnosis apparatus according to claim 2, wherein a diagnosis signal of the apparatus is output in accordance with a detection frequency of a residual voltage within a predetermined time.   A device diagnosis system comprising: a device having a rotating body driven by an AC motor; and the device diagnosis apparatus according to any one of claims 1 to 8. In a device diagnosis method for diagnosing a device having a rotating body driven by an AC motor,
When the electric power supplied to the AC motor is cut off, a residual voltage generated in the AC motor due to the rotation of the rotating body is detected,
Compare the detected residual voltage with the threshold voltage,
The remaining time from the time of occurrence of the residual voltage to the time when the residual voltage becomes smaller than the threshold voltage is counted,
A device diagnosis method, comprising: outputting a diagnosis signal of the device according to the length of the time remaining.

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