Monitoring system

Abstract

To provide a monitoring system capable of more efficiently executing maintenance of a dust filter in an air compressor.SOLUTION: A monitoring system performs monitoring operation on an air compressor in which a compression mechanism configured to be driven by a motor and compress air is provided inside a housing formed so as to allow air to be circulated through a dust filter, where the monitoring operation is an operation of monitoring specific information that has a correlation with the tendency for a temperature inside the housing to rise due to the operation of the compression mechanism.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a monitoring system that performs monitoring operations for an air compressor. Background Art

[0002] Conventionally, air compressors have been used in various fields that utilize compressed air. Generally, in an air compressor, a compression mechanism configured to compress air using a motor is provided inside a ventable housing, such that the compression mechanism is protected by the housing. Further, for example, Patent Document 1 discloses an example of an air compressor in which a compression mechanism and a cooling fan are provided inside a housing.

[0003] In such an air compressor, the cooling fan can be driven to discharge heat generated inside the housing due to driving of the compression mechanism and the like to the outside. Further, by providing a dust filter for removing atmospheric dust at a vent of the housing, it is possible to minimize the entry of dust into the housing while allowing the housing to be ventilated. Prior Art Documents Patent Documents

[0004] Patent Document 1 Japanese Unexamined Patent Application Publication No. 2007-332788 Summary of the Invention Problems to be Solved by the Invention

[0005] As clogging of the dust filter provided in the housing described above progresses, the internal temperature of the housing tends to increase, which may cause various problems. For example, there is a risk that the service life of electrical components inside the housing may be shortened, or the temperature of lubricating oil may increase, which shortens the oil service life and makes sludge more likely to be generated.

[0006] Furthermore, the rate at which dust filters become clogged varies greatly depending on the usage of the air compressor and the surrounding environment (especially the amount of dust). Therefore, it is difficult to perform maintenance efficiently by simply performing regular maintenance on the dust filter (for example, every 500 hours).

[0007] In view of the above-mentioned problems, the present invention aims to provide a monitoring system that enables more efficient maintenance of dust filters in air compressors. [Means for solving the problem]

[0008] The monitoring system according to the present invention is electricity Regarding an air compressor in which a compression mechanism, configured to be driven by a motor and compress air, is installed inside a housing formed to allow ventilation through a dust filter, Data acquisition operation and A monitoring system that performs monitoring operations, The air compressor is configured such that the drive frequency of the electric motor is controlled according to the demand for compressed air, and the data acquisition operation is an operation to acquire time-series monitoring data of at least the drive frequency of the electric motor. The aforementioned monitoring operation is, The load factor of the compression mechanism is calculated based on the ratio of the actual drive frequency to the maximum drive frequency of the electric motor, Monitoring specific information that has a correlation with how easily the temperature inside the enclosure rises. Based on the specified information, the preventive maintenance flag for performing maintenance on the dust filter is updated from off to on. The configuration is such that it performs the action.

[0009] More specifically, the above configuration includes a cooling fan that promotes airflow through the dust filter, and Discharge of compression mechanism The cooling fan is designed to maintain a constant temperature. The fan motor's drive frequency is adjusted by feedback control. It is something that is done, The data acquisition operation is an operation to acquire time-series monitoring data of the drive frequency of the electric motor and the drive frequency of the fan motor. The aforementioned monitoring operation is, This is calculated based on the ratio of the actual drive frequency to the maximum drive frequency of the electric motor. The load factor of the compression mechanism and , calculated based on the ratio of the actual drive frequency to the maximum drive frequency of the fan motor. The operation involves monitoring the relationship between the load rate of the cooling fan and the specified information. The configuration will include the following:

[0010] More specifically, the above configuration is: The air compressor has a cooling fan that promotes airflow through the dust filter, and the drive frequency of the fan motor of the cooling fan is adjusted by feedback control so that the discharge temperature of the compression mechanism is kept constant, and the data acquisition operation is an operation to acquire time-series monitoring data of the drive frequency of the electric motor and the discharge temperature of the compression mechanism. The aforementioned monitoring operation is, This is calculated based on the ratio of the actual drive frequency to the maximum drive frequency of the electric motor. The load factor of the compression mechanism and , the discharge temperature The operation of monitoring the relationship with as the aforementioned specific information. including This will be the structure.

[0011] More specifically with the above configuration, The air compressor has a cooling fan that promotes ventilation through the dust filter, and the drive frequency of the fan motor of the cooling fan is adjusted by feedback control so that the discharge temperature of the compression mechanism is kept constant, and the data acquisition operation is an operation to acquire time-series monitoring data of the drive frequency of the electric motor, the exhaust temperature from the inside to the outside of the housing, and the ambient temperature outside the housing. the monitoring operation is This is calculated based on the ratio of the actual drive frequency to the maximum drive frequency of the electric motor. between the load factor of said compression mechanism and , calculated based on the exhaust temperature and the ambient temperature an operation of monitoring a relationship with a temperature difference as said specific information including which is configured as such.

[0012] More specifically with the above configuration, said specific information obtained in a state where said dust filter is not clogged is stored as reference information, and said monitoring operation is configured to include an operation of determining whether a difference between said specific information and said reference information satisfies a predetermined reference condition.

[0013] More specifically with the above configuration, the present invention comprises each communication unit provided corresponding to each of said plurality of air compressors, and a server capable of communicating with each said communication unit, wherein each said communication unit is configured to transmit the corresponding said air compressor The aforementioned time-series monitor data obtained from to said server, and said server, based on information received from each said communication unit The aforementioned time-series monitoring data , performs said monitoring operation for each of said plurality of air compressors The aforementioned specific information and is configured to perform said monitoring operation.

Effects of the Invention

[0014] According to the monitoring system of the present invention, maintenance of dust filters in an air compressor can be performed more efficiently.

Brief Description of Drawings

[0015] [Figure 1] FIG. 1 is a schematic configuration diagram of a monitoring system 900 according to the present embodiment. [Figure 2] FIG. 2 is a schematic configuration diagram of an air compressor 100 according to the present embodiment. [Figure 3] FIG. 3 is an explanatory diagram showing an example of an external appearance of a housing 20. [Figure 4] FIG. 4 is a flowchart related to a data collection operation. [Figure 5] This is a flowchart related to the situation determination process. [Figure 6] This is an explanatory diagram regarding the relationship R1 between the load factor Lc and the load factor Lf. [Modes for carrying out the invention]

[0016] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. The monitoring system according to this embodiment is a system that performs monitoring operations for each of the multiple air compressors.

[0017] 1. Configuration of the monitoring system, etc. First, the configuration of the monitoring system according to this embodiment will be described. Figure 1 illustrates a schematic configuration of the monitoring system 900 according to this embodiment. The monitoring system 900 is configured to include a LAN (Local Area Network) 300 and a server 500. The LAN 300 is configured to include a mesh-type wireless network 210.

[0018] The wireless network 210 is a communication network composed of communication devices (nodes) consisting of a slave unit (hereinafter referred to as "communication unit 200"), a repeater 201, and a master unit 202, each of which is provided in a one-to-one correspondence with each of the multiple air compressors 100. The wireless network 210 enables wireless communication between multiple nodes located within a local area, such as a factory, and in cases where radio waves cannot reach directly, the nodes in between can relay the signals to enable mutual communication.

[0019] One of the features of the wireless network 210's communication protocol is its multi-hop function, which allows packets to be sent to the target node by passing through multiple nodes (hopping). Therefore, even when a communication unit 200 is installed in a location where radio waves are difficult to reach due to distance or other reasons, mutual communication with other nodes becomes possible by installing a repeater 201. Furthermore, when adding a new communication unit 200, the burden of wiring work is reduced, and the communication network can be easily expanded. In addition, by arranging the nodes in a mesh pattern, even if a node fails, communication can still be maintained through other functioning nodes.

[0020] In LAN300, all communication units 200 are connected to a master unit 202 via a wireless network 210, and the master unit 202 is further connected to a server 500 via a data line termination device 203 and the internet 400. This allows the server 500 to communicate with each communication unit 200. Information transmitted from each communication unit 200 is sent to the server 500 via LAN300 and the internet 400.

[0021] In this way, the monitoring system 900 can have the server 500 collect the information transmitted from each communication unit 200. Furthermore, if necessary, the server 500 can be connected to another LAN via the internet 400 to expand the scale of the monitoring system 900.

[0022] Each communication unit 200 can communicate with the corresponding air compressor 100 (control device 10, described later), acquire a set of monitor data (data of the monitoring results for each item) from the air compressor 100, and transmit this set of monitor data, along with the device ID, to the server 500. The device ID is information that allows the air compressor 100 to be identified by other air compressors 100. Based on the information received from each communication unit 200, the server 500 can monitor each of the multiple air compressors 100. The server 500 has the device IDs for all air compressors 100 pre-registered, and can record information for each device ID.

[0023] 2. Air compressor configuration, etc. Next, we will explain the configuration of the air compressor 100. Figure 2 shows a schematic configuration of the air compressor 100.

[0024] As shown in this figure, the air compressor 100 has a configuration in which the following elements are arranged inside the housing 20: a compression mechanism 1, an oil separator 2, an automatic temperature control valve 3, an oil cooler 4, an oil filter 6, an inverter 7, an intake filter 8, a cooling fan 9, a control device 10, and a fan motor 91. The compression mechanism 1 includes a compressor body 51 and an electric motor 52, etc.

[0025] In this embodiment, the air compressor 100 is configured as an oil-lubricated air compressor, and the compressor body 51 compresses the air Aa drawn in from the outside into compressed air Ab, which can then be discharged to, for example, various pneumatic devices. The air compressor 100 can employ various configurations as long as they do not depart from the spirit of the present invention, and may also be configured as an oil-free air compressor.

[0026] Furthermore, as illustrated in Figure 3, the housing 20 is formed to allow ventilation through a dust filter 12 for removing dust from the atmosphere. More specifically, at least a portion of the housing 20 is provided with vents that allow for ventilation between the inside and outside, and the dust filter 12 is positioned to cover these vents from the outside.

[0027] In this way, by providing the dust filter 12 at the ventilation opening of the housing 20, the housing 20 can be ventilated while minimizing the entry of dust into the inside of the housing 20. The dust filter 12 may be detachable from the housing 20, making it easy to remove the dust filter 12 from the housing 20 for cleaning or to replace it with a new one as needed.

[0028] In Figure 2, the white arrows schematically show the paths of air Aa and compressed air Ab, and the thick arrow schematically shows the lubricating oil circulation circuit X through which the lubricating oil Lu circulates. The path for introducing air Aa from the outside to the inside of the housing 20 may be a path through the dust filter 12, or it may be a separate path (for example, a dedicated path for air Aa). In this embodiment, the compressed air Ab that comes out of the compressor body 51 is discharged to the outside through the oil separator 2. The lubricating oil circulation circuit X shown in Figure 2 is a path that circulates the lubricating oil Lu by passing it through predetermined locations (such as the compressor body 51) in the compression mechanism 1 where friction reduction and cooling are performed using lubricating oil Lu.

[0029] The lubricating oil circulation circuit X has a path through which lubricating oil Lu flows from the compressor body 51 to the compressor body 51, passing sequentially through the oil separator 2, automatic temperature control valve 3, oil cooler 4, and oil filter 6. The lubricating oil circulation circuit X also has an auxiliary path Xa connecting the position between the oil cooler 4 and oil filter 6 to the automatic temperature control valve 3.

[0030] The compressor body 51 is driven by an electric motor 52 and operates to compress air Aa to produce compressed air Ab. In this embodiment, a rotary (screw) compressor is used as the compressor body 51, and the compressor body 51 uses lubricating oil Lu to reduce friction and cool the screw rotor (remove compression heat and frictional heat). The electric motor 52 is configured to be driven by AC power supplied from an external source (such as commercial power) and drives the rotor of the compressor body 51.

[0031] The compressed air Ab generated by the compressor body 51 contains lubricating oil Lu. Therefore, the oil separator 2 receives the compressed air Ab from the compressor body 51, separates the lubricating oil Lu contained in this compressed air Ab, and temporarily stores it. The portion of the lubricating oil circulation circuit X from the compressor body 51 to the oil separator 2 is the path for the lubricating oil Lu contained in the compressed air Ab.

[0032] The automatic temperature control valve 3 is a three-way valve that plays a role in regulating the temperature of the lubricating oil Lu. In this embodiment, the automatic temperature control valve 3 operates, for example, to increase the amount of lubricating oil Lu passing through the auxiliary path Xa when the temperature of the lubricating oil Lu is lower than a predetermined reference value. This reduces the amount of lubricating oil Lu passing through the oil cooler 4, thereby suppressing the temperature drop of the lubricating oil Lu.

[0033] The oil cooler 4 includes a water-cooled oil cooler that cools the lubricating oil Lu by water cooling, and an air-cooled oil cooler that cools the lubricating oil Lu by air cooling. The water-cooled oil cooler recovers waste heat contained in the lubricating oil Lu, and while primary cooling the lubricating oil Lu through heat exchange with the cooling water, it also warms the cooling water. The warm water generated by the water-cooled oil cooler is used in the factory as boiler feedwater, etc.

[0034] The air-cooled oil cooler is configured to allow the lubricating oil Lu to pass through after it has passed through the water-cooled oil cooler, and to secondarily cool the lubricating oil Lu through heat exchange between the lubricating oil Lu and cooling air (outside air drawn into the housing 20 by the operation of the cooling fan 9). The oil cooler 4 may have only one of the water-cooled oil cooler or the air-cooled oil cooler. The oil filter 6 is a filter that removes impurities such as iron rust and sludge from the lubricating oil Lu.

[0035] The lubricating oil Lu circulating in the lubricating oil circulation circuit X first plays a role in reducing friction in the compressor body 51, and then flows into the oil separator 2 where it is separated from the compressed air Ab. This lubricating oil Lu is temporarily stored in the oil separator 2, and then cooled as it passes through the automatic temperature control valve 3 and the oil cooler 4. After impurities are removed from this cooled lubricating oil Lu in the oil filter 6, it flows into the compression mechanism 1 where it is used for friction reduction and cooling where necessary, and then returns to the compressor body 51.

[0036] Furthermore, the compressed air Ab separated by the oil separator 2 is cooled by an aftercooler (not shown) located inside the housing 20 before being supplied to the outside. The aftercooler preferably includes a water-cooled aftercooler that cools the compressed air Ab by water cooling, and an air-cooled oil cooler that cools the compressed air Ab by air cooling. The water-cooled aftercooler recovers the waste heat contained in the compressed air Ab, and while primary cooling the compressed air Ab through heat exchange between the compressed air Ab and the cooling water, it also warms the cooling water. The cooling water may be supplied in series to the water-cooled oil cooler and the water-cooled aftercooler, or in parallel.

[0037] The air-cooled aftercooler is configured to pass the compressed air Ab that has passed through the water-cooled aftercooler, and to secondarily cool the compressed air Ab through heat exchange between the compressed air Ab and the cooling air (outside air drawn into the enclosure 20 by the operation of the cooling fan 9). The aftercooler may consist of only one of the two types: a water-cooled aftercooler or an air-cooled aftercooler.

[0038] The inverter 7 converts AC power supplied from an external source to the electric motor 52 into AC power. The operation of the inverter 7 can be controlled by the control device 10, which in turn allows the control device 10 to control the drive frequency Fm of the electric motor 52. Increasing the drive frequency Fm increases the rotational speed of the electric motor 52, which in turn increases the amount of compressed air Ab produced by the compressor body 51.

[0039] The intake filter 8 is installed in the intake path of air Aa to the compressor body 51 and is a filter that removes dust. The air Aa drawn in from outside the housing 20 has dust removed as it passes through the intake filter 8 before being sent to the compressor body 51.

[0040] The cooling fan 9 promotes airflow through the dust filter 12 to cool the inside of the enclosure 20, and also blows cooling air to the air-cooled oil cooler and air-cooled aftercooler mentioned above. The temperature inside the enclosure 20 tends to rise more easily than the ambient temperature due to heat generated by electrical components such as the electric motor 52 and the heat of air compression in the compressor body 51. Since a rise in the temperature inside the enclosure 20 can lead to deterioration of electrical components and lubricating oil Lu, it is important to cool the inside of the enclosure 20 appropriately with the cooling fan 9.

[0041] The drive frequency Ff of the fan motor 91 that drives the cooling fan 9 can be controlled by the control device 10. The higher the drive frequency Ff, the higher the rotational speed of the fan motor 91, which further promotes airflow through the dust filter 12 and enhances the cooling effect of the cooling fan 9.

[0042] The control device 10 controls and monitors each part of the air compressor 100 to ensure that the air compressor 100 operates normally. The control device 10 can also communicate with the communication unit 200 (see Figure 1) which is compatible with the air compressor 100.

[0043] The control device 10 drives the cooling fan 9 so that the temperature of a predetermined location within the housing 20 (in this embodiment, the inside of the oil separator 2) is kept constant. More specifically, the control device 10 monitors the internal temperature of the oil separator 2 as the discharge temperature Td and adjusts the drive frequency Ff of the fan motor 91 using PID feedback control so that this discharge temperature Td is kept constant. This discharge temperature Td may also be the temperature of the lubricating oil Lu temporarily stored in the oil separator 2. If an oil-free type air compressor 100 is used, for example, the two-stage discharge temperature may be used as the discharge temperature Td.

[0044] The control device 10 also controls the drive frequency Fm of the electric motor 52 according to, for example, the demand for compressed air Ab. This makes it possible to increase the drive frequency Fm as the demand for compressed air Ab increases, thereby generating more compressed air Ab. Furthermore, the control device 10 monitors the ambient temperature Ta (temperature outside the housing 20) of the air compressor 100 and the exhaust temperature Te, which is the temperature of the exhaust from the inside of the housing 20 to the outside. The exhaust temperature Te may be the temperature of the compressed air Ab just before it is discharged from the housing 20 (compressed air Ab after passing through the air-cooled aftercooler), or it may be the temperature of the air just before it is discharged from the housing 20 via the dust filter 12 by the cooling fan 9.

[0045] Here, the load factor of the cooling fan 9 is influenced by the load factor of the compression mechanism 1, and the larger the load factor of the compression mechanism 1, the larger the load factor of the cooling fan 9. The load factor of the cooling fan 9 [%] is the ratio of the actual drive frequency of the fan motor 91 to its maximum drive frequency, or the ratio of the actual rotational speed to its maximum rotational speed, and indicates the relative magnitude of the airflow provided by the cooling fan 9. The load factor of the compression mechanism 1 [%] is the ratio of the actual drive frequency of the electric motor 52 to its maximum drive frequency, or the ratio of the actual rotational speed to its maximum rotational speed, and indicates the relative magnitude of the heat input from compression.

[0046] When the dust filter 12 becomes clogged, the load on the cooling fan 9 increases as a primary phenomenon in order to maintain the airflow. Furthermore, as the clogging progresses, the airflow decreases even when the load on the cooling fan 9 is adjusted to the maximum, so as a secondary phenomenon, the discharge temperature Td increases, and the exhaust temperature Te also increases. In addition, when the exhaust temperature Te rises, the temperature difference between the exhaust temperature Te and the ambient temperature Ta increases.

[0047] As the dust filter 12 becomes more clogged, the temperature inside the housing 20 rises more easily due to the operation of the compression mechanism 1. Therefore, by monitoring information that correlates with this tendency to rise in temperature (hereinafter sometimes referred to as "specific information"), it becomes possible to determine whether or not maintenance of the dust filter 12 is necessary. Examples of this specific information include the information relating (correlation) shown in (A) to (C) below. (A) Relationship between the load factor of the compression mechanism 1 and the load factor of the cooling fan 9 (B) Relationship between the load factor and discharge temperature Td of the compression mechanism 1 (C) Relationship between the load factor and temperature difference (exhaust temperature Te - ambient temperature Ta) of compression mechanism 1

[0048] Therefore, in the monitoring system 900 according to this embodiment, monitoring operations are performed focusing on the relationships described in (A) to (C) above to determine whether or not maintenance of the dust filter 12 is necessary. The specific details of the operation of the monitoring system 900 will be described below.

[0049] 3. Operation of the monitoring system, etc. The monitoring system 900 performs monitoring operations for each air compressor 100 to determine whether maintenance of the dust filter 12 is required. In this embodiment, the monitoring system 900 performs data collection operations to have the server 500 collect a group of monitor data M from each air compressor 100, and status determination operations to determine whether predetermined conditions have been met based on the group of monitor data M.

[0050] First, the data acquisition operation will be explained below with reference to the flowchart shown in Figure 4. When the main power of the corresponding air compressor 100 is turned ON, each communication unit 200 starts the operation to acquire the monitor data group M (step S11). In this embodiment, the monitor data group M includes the aforementioned monitor data for the drive frequency Fm of the electric motor 52, the drive frequency Ff of the fan motor 91, the discharge temperature Td, the ambient temperature Ta, and the exhaust temperature Te. Each monitor data includes values ​​(time-series data) that are acquired sequentially in synchronization at a predetermined period (for example, every minute), and all values ​​in each monitor data are accompanied by information on the date and time when the value was acquired. Each communication unit 200 continuously receives and acquires the monitor data group M from the control device 10 of the corresponding air compressor 100 and temporarily records it until it is transmitted to the server 500.

[0051] Furthermore, each communication unit 200 performs the operation to acquire the monitor data group M while monitoring for the timing to transmit the monitor data group M (step S12). Whenever this transmission timing arrives (Yes in step S12), each communication unit 200 transmits the monitor data group M newly recorded since the previous transmission, along with the device ID of the corresponding air compressor 100, to the server 500 (step S13). In this embodiment, each communication unit 200 is configured to transmit the monitor data group M to the server 500 at regular intervals (for example, intervals of 30 to 120 minutes), and transmits the newly recorded monitor data group M to the server 500 at each of these intervals.

[0052] Meanwhile, the server 500 waits to receive the monitor data group M and device ID from each communication unit 200 (step S21). Whenever the server 500 receives the monitor data group M and device ID from any of the communication units 200 (Yes in step S21), the server 500 records the monitor data group M as information related to the device ID (step S22).

[0053] By performing this series of data collection operations (steps S11 to S22), it becomes possible to have the server 500 collect information from the monitor data group M for each air compressor 100.

[0054] Next, the situation determination operation will be explained below with reference to the flowchart shown in Figure 5. In this embodiment, this situation determination operation is performed by the server 500 based on the monitor data group M when a new monitor data group M is recorded in the server 500 by the data collection operation.

[0055] Based on the monitor data group M, the server 500 calculates the load factor Lc of the compression mechanism 1, the load factor Lf of the cooling fan 9, and the temperature difference ΔT (= exhaust temperature Te - ambient temperature Ta) between the exhaust temperature Te and the ambient temperature Ta (step S31). The server 500 has pre-registered information on the maximum drive frequency Fmo of the electric motor 52 and the maximum drive frequency Ffo of the fan motor 91. The server 500 calculates the load factor Lc[%] of the compression mechanism 1 as the ratio of the drive frequency Fm of the electric motor 52 to the maximum drive frequency Fmo of the electric motor 52 (= drive frequency Fm / maximum drive frequency Fmo × 100), and calculates the load factor Lf[%] of the cooling fan 9 as the ratio of the drive frequency Ff of the fan motor 91 to the maximum drive frequency Ffo of the fan motor 91 (= drive frequency Ff / maximum drive frequency Ffo × 100).

[0056] Furthermore, the load factor Lc of the compression mechanism 1 may be calculated as the ratio of the actual rotational speed of the electric motor 52 to the maximum rotational speed of the electric motor 52, and the load factor Lf of the cooling fan 9 may be calculated as the ratio of the actual rotational speed of the fan motor 91 to the maximum rotational speed of the fan motor 91. In addition, if the air volume of the cooling fan 9 in the air compressor 100 can be detected by an air volume sensor or the like, the value of that air volume may be used instead of the load factor Lf of the cooling fan 9.

[0057] Next, the server 500 determines whether the difference Z between the reference information B and any of the following relationships R1 (the relationship between the load factor Lc of the compression mechanism 1 and the load factor Lf of the cooling fan 9), R2 (the relationship between the load factor Lc of the compression mechanism 1 and the discharge temperature Td), and R3 (the relationship between the load factor Lc of the compression mechanism 1 and the temperature difference ΔT) has reached a predetermined reference condition C (step S32). Each of these relationships R1 to R3 corresponds to specific information that has a correlation with how easily the temperature inside the housing 20 rises due to the operation of the compression mechanism 1.

[0058] Here, the relationship R1 between the load factor Lc of the compression mechanism 1 and the load factor Lf of the cooling fan 9 is expressed as a position on a coordinate system, assuming a coordinate system that shows the relationship between load factors Lc and Lf as shown in Figure 6. For example, when the load factor Lc is X1 and the load factor Lf is Y1, the relationship R1 is represented by the coordinates (X1, Y1) in Figure 6. Furthermore, the reference information B for relationship R1 is represented, for example, by the reference line Ba shown in Figure 6 (i.e., information that identifies the load factor Lf for any load factor Lc). In this example, the difference Z between the relationship R1 represented by the coordinates (X1, Y1) and the reference information B is Y1-Y2 (i.e., the difference between load factors Lf after unifying the load factor Lc), as shown in Figure 6.

[0059] In this embodiment, the reference information B (reference line Ba) relating to relation R1 is information that identifies the load factor Lf for any load factor Lc in the air compressor 100 when the dust filter 12 is not clogged (for example, in an unused state with no clogging at all). Furthermore, the reference condition C relating to relation R1 can be set, for example, as the allowable increase amount α (for example, a value selected in the range of 5 to 10%) for the load factor Lf in the reference information B at that time. In this case, in the example of Figure 6, if the equation Z≧α is satisfied, then the difference between relation R1 and reference information B has reached reference condition C. That is, when the load factor Lc is X1, if the load factor Lf increases by α or more from Y2 to Y1, then Z≧α is satisfied. Note that although relation R1 has been described here as an example, relation R2 and relation R3 are similar, except that the load factor Lf is replaced by the discharge temperature Td or the temperature difference ΔT.

[0060] If, as a result of the determination in step S32 described above, the difference Z between the reference information B and any of the relationships R1 to R3 reaches the reference condition C (Yes in step S32), the server 500 updates the preventive maintenance flag to ON (step S33) and then terminates the current status determination operation. In other words, the server 500 has previously recorded and stored information on the preventive maintenance flag (initial value is "OFF") indicating whether maintenance of the dust filter 12 is necessary for each device ID, and the operation in step S33 updates the preventive maintenance flag corresponding to the device ID related to the current status determination operation (the device ID corresponding to the monitor data group M used in the current status determination operation) to "ON".

[0061] On the other hand, if the difference Z between any of the relationships R1 to R3 and the reference information B does not reach the reference condition C (No. in step S32), the server 500 terminates the current status determination operation without performing the operation in step 33.

[0062] The status of the preventive maintenance flag for each device ID, which is recorded and stored on the server 500, can be checked by the business operator (facility management agent) responsible for the maintenance of each air compressor 100, making it easy to determine which air compressor 100 requires maintenance of the dust filter 12. This allows, for example, a field engineer performing maintenance work under the aforementioned business operator to incorporate maintenance (cleaning, replacement, etc.) of the dust filter 12 of the air compressor 100 corresponding to a particular device ID into their action plan when the preventive maintenance flag for that device ID is turned ON. Furthermore, the preventive maintenance flag that has been set to "ON" can be updated to "OFF" after maintenance is performed, thereby enabling further monitoring.

[0063] As described above, the monitoring system 900 of this embodiment allows for efficient maintenance of the dust filter 12 for each air compressor 100, and minimizes the risk of various problems caused by clogging of the dust filter 12.

[0064] 4. Others As described above, the monitoring system 900 according to this embodiment is a monitoring system that performs monitoring operations with respect to an air compressor 100, which is provided inside a housing 20 formed to allow ventilation via a dust filter 12, and which has a compression mechanism 1 configured to be driven by an electric motor 52 to compress air Aa. This monitoring operation is an operation that monitors specific information that has a correlation with how easily the temperature inside the housing 20 rises due to the driving of the compression mechanism 1. Therefore, with the monitoring system 900, it becomes possible to perform maintenance on the dust filter 12 in the air compressor 100 more efficiently.

[0065] The monitoring system 900 also monitors the relationship R1 between the load factor Lc of the compression mechanism 1 and the load factor Lf of the cooling fan 9, the relationship R2 between the load factor Lc of the compression mechanism 1 and the discharge temperature Td, and the relationship R3 between the load factor Lc of the compression mechanism 1 and the temperature difference ΔT as specific information, and determines whether the difference between the specific information and the reference information B has reached the reference condition C. The monitoring system 900 may monitor only one or two of the relationships R1 to R3 instead of all of them.

[0066] Furthermore, regarding the type of air compressor, in this embodiment, an inverter-type air compressor 100, in which the amount of air compression can be adjusted by controlling the drive frequency of the electric motor 52 (main motor), was given as an example. However, it is also possible to use a load / unload type air compressor that is controlled to repeatedly cycle between load operation (a state in which compressed air is produced) and unload operation (a state in which it is idle and waiting).

[0067] In this case, the load factor of the compression mechanism can be set to 100% during load operation and 10% during unload operation, for example. In this example, the load factor is considered to be 10% considering that the bearing and shaft seal parts of the compression mechanism are also subjected to load during unload operation. In this case, the contents of the monitor data group M can be changed from the drive frequency Fm to the load operation signal (a signal that indicates ON during load operation) and the unload operation signal (a signal that indicates ON during unload operation). Then, in the operation of step S31, if the load operation signal is ON, the load factor Lc of the compression mechanism should be set to 100%, and if the unload operation signal is ON, the load factor Lc of the compression mechanism should be set to 10%.

[0068] The monitoring system 900 also includes a communication unit 200, each corresponding to one of the multiple air compressors 100, and a server 500 capable of communicating with each communication unit 200. Each communication unit 200 transmits information relating to the specific information of the corresponding air compressor 100 to the server 500, and the server 500 performs monitoring operations for each of the multiple air compressors 100 based on the information received from each communication unit 200.

[0069] Therefore, according to the monitoring system 900, the server 500 can monitor each of the multiple air compressors 100, enabling efficient monitoring. Furthermore, if, for example, multiple air compressors 100 are distributed throughout the factory, the data transmitted from the communication unit 200 to the server 500 may include location information of the air compressor 100 corresponding to that communication unit 200.

[0070] Although embodiments of the present invention have been described above, the configuration of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the invention. In other words, the above embodiments should be considered to be illustrative in all respects and not restrictive. The technical scope of the present invention is indicated not by the above description of embodiments, but by the claims, and should be understood to include all modifications that fall within the meaning and scope equivalent to the claims. [Explanation of Symbols]

[0071] 1. Compression mechanism 2 Oil Separator 3. Automatic temperature control valve 4. Oil cooler 6. Oil filter 7 Inverter 8. Intake filter 9 Cooling fan 10 Control device 12 Dust filters 20 cabinets 51 Compressor body 52 Electric motor 91 Fan motor 100 Air Compressor 200 communication units 201 Repeater 202 Main Unit 203 Data Line Termination Equipment 210 Wireless Networks 300 LAN 400 Internet 500 servers 900 monitoring systems Aa Air Ab Compressed air Lu Lubricant X Lubricating oil circulation circuit Xa Auxiliary path

Claims

1. A monitoring system for performing data acquisition and monitoring operations, relating to an air compressor having a compression mechanism configured to be driven by an electric motor and to compress air, installed inside a housing formed to allow ventilation through a dust filter, The air compressor is configured such that the drive frequency of the electric motor is controlled according to the demand for compressed air. The data acquisition operation is an operation to acquire time-series monitoring data of at least the drive frequency of the electric motor, The aforementioned monitoring operation is, The system monitors specific information that has a correlation between the load factor of the compression mechanism, calculated based on the ratio of the actual drive frequency to the maximum drive frequency of the electric motor, and the ease with which the temperature inside the housing rises. A monitoring system characterized by an operation to update a preventive maintenance flag for performing maintenance on the dust filter from off to on, based on the aforementioned specific information.

2. The air compressor has a cooling fan that promotes airflow through the dust filter, and the drive frequency of the fan motor of the cooling fan is adjusted by feedback control so that the discharge temperature of the compression mechanism is kept constant. The data acquisition operation is an operation to acquire time-series monitoring data of the drive frequency of the electric motor and the drive frequency of the fan motor. The monitoring system according to claim 1, characterized in that the monitoring operation includes monitoring the relationship between the load factor of the compression mechanism, which is calculated based on the ratio of the actual drive frequency to the maximum drive frequency of the electric motor, and the load factor of the cooling fan, which is calculated based on the ratio of the actual drive frequency to the maximum drive frequency of the fan motor, as the specific information.

3. The air compressor has a cooling fan that promotes airflow through the dust filter, and the drive frequency of the fan motor of the cooling fan is adjusted by feedback control so that the discharge temperature of the compression mechanism is kept constant, The data acquisition operation is an operation to acquire time-series monitoring data of the drive frequency of the electric motor and the discharge temperature of the compression mechanism. The monitoring system according to claim 1, characterized in that the monitoring operation includes monitoring the relationship between the load factor of the compression mechanism, which is calculated based on the ratio of the actual drive frequency to the maximum drive frequency of the electric motor, and the discharge temperature, as the specific information.

4. The air compressor has a cooling fan that promotes airflow through the dust filter, and the drive frequency of the fan motor of the cooling fan is adjusted by feedback control so that the discharge temperature of the compression mechanism is kept constant. The data acquisition operation involves acquiring time-series monitoring data of the drive frequency of the electric motor, the exhaust temperature from the inside to the outside of the housing, and the ambient temperature outside the housing. The monitoring system according to claim 1, characterized in that the monitoring operation includes monitoring the relationship between the load factor of the compression mechanism, which is calculated based on the ratio of the actual drive frequency to the maximum drive frequency of the electric motor, and the temperature difference, which is calculated based on the exhaust temperature and the ambient temperature, as the specific information.

5. The aforementioned specific information, obtained when the dust filter is not clogged, is stored as reference information. The aforementioned monitoring operation is, A monitoring system according to any one of claims 1 to 3, characterized in that it includes an operation to determine whether the difference between the specified information and the standard information has reached a predetermined standard condition.

6. Each of the multiple air compressors is provided with a corresponding communication unit, The system includes a server capable of communicating with each of the aforementioned communication units, Each of the aforementioned communication units transmits the time-series monitoring data acquired from the corresponding air compressor to the server. The monitoring system according to any one of claims 1 to 3, characterized in that the server performs the monitoring operation for the specific information for each of the plurality of air compressors based on the time-series monitoring data received from each of the communication units.

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