gas compressor

Abstract

The objective is to optimize the cleaning or replacement frequency of pre-filters for compressed air and cooling air. [Solution] A gas compressor is provided, comprising a compressed air pre-filter for primary dust removal positioned at the compressed air intake port of the housing, an intake filter for further secondary dust removal, at least one compressor body that draws in and compresses air through the intake filter and intake passage, a motor that drives the compressor body, an air cooler for cooling the compressed air, a cooling fan that passes cooling air to the air cooler, a cooling air intake port that draws in outside air by the cooling fan, a cooling air pre-filter provided at the cooling air intake port, and a control device that controls the operation of the compressor, wherein the control device determines the frequency of cleaning or replacing the compressed air pre-filter and the cooling air pre-filter from the load factor, which is an indicator of the operating state.

Description

Technical Field

[0001] The present invention relates to a gas compressor.

Background Art

[0002] Among gas compressors, for example, in a compressor that sucks and compresses air as a gas, one or more intake filters are provided to filter the air flowing into the compressor main body equipped with a reciprocating body or a rotating body inside. Further, the compressor main body is installed in a housing for sound insulation and weather resistance, and an outside air filter for removing dust and the like in the outside air to some extent may be provided at an intake port provided in the housing. A technique is known in which clean air is sucked into the compressor main body by a multi-stage filter. As this type of conventional technology, for example, there is Patent Document 1.

[0003] In Patent Document 1, in a system for predicting the deterioration rate of components of a turbomachine using state-based monitoring, a compressor deterioration prediction model that provides a function of the performance of a compressor based on sensor data, one or more filter deterioration rates, or some combination thereof is used to predict the compressor deterioration rate for the compressor, and one or more preventive actions are executed based on the predicted compressor deterioration rate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Patent Document 1 discusses a filter degradation prediction model for calculating filter degradation rate. It predicts that the amount of intake air passing through the filter and the compressor's load operation time also have a significant impact on the prediction model. However, it does not specifically mention the relationship between the compressor's drive method, which is related to the amount of air, the ratio of the opening time of the intake valve provided in the compressor to the operating time, or the load factor, which is an indicator of the compressor's operating state and is determined by parameters such as the rotational speed of the motor or prime mover that drives the compressor body.

[0006] Furthermore, Patent Document 1 does not specifically describe any method for determining when to clean or replace a pre-filter in a configuration where a pre-filter for primary removal of atmospheric dust is placed further upstream of the filter house.

[0007] Furthermore, while the filter described in Patent Document 1 filters the air inhaled by the turbo compressor body, in the case of a compressor equipped with an air-cooled cooler for cooling compressed air, a cooling fan may be provided, and a pre-filter for the cooler that removes dust as a primary measure may be installed at the intake port of the cooling fan. However, no consideration of a filter degradation prediction model for the aforementioned pre-filter for the cooler is mentioned.

[0008] In view of the above problems, the object of the present invention is to optimize the frequency of cleaning or replacing pre-filters for compressed air and pre-filters for cooling air. [Means for solving the problem]

[0009] To give one example, the present invention provides a gas compressor comprising: a compressed air pre-filter for primary removal of dust at the compressed air intake port of the housing; an intake filter for further secondary removal of dust; at least one compressor body that draws in and compresses air through the intake filter and intake passage; a motor that drives the compressor body; an air cooler for cooling the compressed air; a cooling fan that passes cooling air to the air cooler; a cooling air intake port that draws in cooling air from the outside air by the cooling fan; a cooling air pre-filter provided at the cooling air intake port; and a control device that controls the operation of the compressor, wherein the control device determines the frequency of cleaning or replacing the compressed air pre-filter and the cooling air pre-filter from the load factor, which is an indicator of the operating state. [Effects of the Invention]

[0010] According to the present invention, the effect of optimizing the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air can be obtained. [Brief explanation of the drawing]

[0011] [Figure 1] This is a system diagram showing the components of the gas compressor in Example 1. [Figure 2] This is a flowchart illustrating the process for determining when to clean or replace the pre-filters for compressed air and cooling air in Example 1. [Figure 3] This is a flowchart illustrating the process for determining when to clean or replace the pre-filter in Example 2. [Figure 4] This is a diagram showing the components of the gas compressor in Example 3. [Figure 5] This figure shows the relationship between the output frequency of the cooling fan inverter and the inverter input current in Example 4. [Figure 6] This is a flowchart illustrating the process for determining when to clean or replace the pre-filter in Example 4. [Figure 7] This is a system diagram showing the components of the gas compressor in Example 5. [Figure 8] This is a diagram showing the components of the gas compressor in Example 6. [Modes for carrying out the invention]

[0012] Examples of the present invention will be described below with reference to the figures. [Examples]

[0013] In this embodiment, an air-cooled, oil-free, two-stage screw air compressor is used as an example of the gas compressor.

[0014] Figure 1 is a system diagram showing the components of the gas compressor in this embodiment. In Figure 1, the gas compressor 1 is configured to compress air in two stages, and the low-pressure stage compressor body 101 and the high-pressure stage compressor body 102 are driven to draw in, compress, and discharge air.

[0015] In Figure 1, the low-pressure stage compressor body 101, the high-pressure stage compressor body 102, the motor 103, and the oil pump 105 are fixed to the speed increaser case 104. A low-pressure stage pinion 107 is attached to the tip of the drive shaft of the low-pressure stage compressor body 101, and a high-pressure stage pinion 108 is attached to the tip of the drive shaft of the high-pressure stage compressor body 102. A bull gear 106 and an oil pump pinion 109 are fitted to the drive shaft of the motor 103 from the base side of the drive shaft. The bull gear 106 meshes with the low-pressure stage pinion 107 and the high-pressure stage pinion 108, and the oil pump pinion 109 meshes with the oil pump gear 110. When the motor 103 is driven, the bull gear 106 rotates, which drives the low-pressure stage compressor body 101, the high-pressure stage compressor body 102, and the oil pump 105.

[0016] At the start of operation, the motor 103 drives the low-pressure stage compressor body 101 and the high-pressure stage compressor body 102, and the suction valve 301 opens. Air is sucked in from the atmosphere through the compressed air pre-filter 600a provided at the air inlet 2a of the housing of the gas compressor 1. Dust is primarily separated from the sucked-in air, and the air passes through the intake duct 2b. Further dust is secondarily separated by the intake filter 601, and highly clean air flows into the low-pressure stage compressor body 101 through the intake air path 401, which is the intake passage, and the suction valve 301.

[0017] The low-pressure stage compressor body 101 compresses air to a predetermined pressure, and the compressed air flows into the intercooler 201 through the low-pressure stage discharge air path 402. The intercooler 201 is an air-cooled heat exchanger, that is, an air cooler. The high-temperature compressed air is cooled by passing through the cooling air generated by the cooling fan 204. The compressed air cooled by the intercooler 201 passes through the high-pressure stage intake air path 403 and flows into the high-pressure stage compressor body 102, where the air is compressed to a higher pressure. The high-pressure compressed air discharged from the high-pressure stage compressor body 102 passes through the high-pressure stage discharge air path 404 and flows into the aftercooler 202. The aftercooler 202 is also an air-cooled heat exchanger similar to the intercooler 201, that is, an air cooler, and cools the compressed air by the cooling air of the cooling fan 204. The compressed air cooled by the aftercooler 202 passes through the discharge air path 405 and is supplied to the destination that requires the compressed air.

[0018] The pre-filter 600a for compressed air generally has a relatively lower filtration accuracy than the intake filter 601, and is intended to primarily remove relatively large foreign objects and dust, thereby expecting to delay the clogging of the intake filter 601. Similarly, by attaching the pre-filter 600b for cooling air to the intake port 3a for cooling air, relatively large foreign objects and dust are removed in the same way. Therefore, the air sucked in by the cooling fan 204 through the intake port 3a for cooling air and the cooling air duct 3b becomes somewhat clean, and it is possible to reduce the clogging of dust on the cooling fin portions of the air-cooled intercooler 201, aftercooler 202, and oil cooler 203. The cooling air that has passed through the intercooler 201, aftercooler 202, and oil cooler 203 and exchanged heat with the high-temperature compressed air and lubricating oil passes through the fan duct 004b and is discharged to the atmosphere from the exhaust port 004a.

[0019] The low-pressure stage compressor body 101, high-pressure stage compressor body 102, speed increasing device case 104, and oil pump 105 incorporate bearings for supporting internal rotating bodies (not shown). Also, since the bull gear 106, low-pressure stage pinion 107, high-pressure stage pinion 108, oil pump pinion 109, and oil pump gear 110 rotate while meshing with each other, these mechanical parts generally require a lubricant. In this embodiment, lubricating oil is stored in the lower part of the speed increasing device case 104.

[0020] When the oil pump 105 is driven by the motor 103, lubricating oil is sucked in from the lower part of the speed increasing device case 104, passes through the suction oil pipe 411, flows into the oil pump 105, and is discharged. The lubricating oil discharged from the oil pump 105 passes through the discharge oil path 412, is cooled by the oil cooler 203 which is an air-cooled heat exchanger, and then is sent to the main oil supply path 413. An oil filter 603 is installed in the middle of the main oil supply path 413. Also, the main oil supply path 413 branches into a low-pressure stage oil supply path 414, a high-pressure stage oil supply path 415, and a speed increasing device oil supply path 416 to supply lubricating oil to the low-pressure stage compressor body 101, high-pressure stage compressor body 102, and speed increasing device case 104.

[0021] The compressed air path includes a release device for releasing compressed air remaining in the compressed air path when the gas compressor is operating under no load or when it is stopped. Release valves 302 and 303 release compressed air from the air path from the discharge side of the high-pressure stage compressor body 102 to the check valve 305.

[0022] Various sensors are installed throughout the interior of the gas compressor 1 for the control device 703 to determine whether the gas compressor is operating normally and to control the operation of the gas compressor. For example, an intake pressure sensor 501 is provided on the intake air path 401, a low-pressure stage discharge air temperature sensor 505 is provided on the low-pressure stage discharge air path 402, a high-pressure stage intake air pressure sensor 502 and a high-pressure stage intake air temperature sensor 506 are provided on the high-pressure stage intake air path 403, a high-pressure stage discharge air temperature sensor 507 is provided on the high-pressure stage discharge air path 404, and a discharge air pressure sensor 503 is provided on the discharge air path 405. In addition, an oil pressure sensor 504 and an oil temperature sensor 508 are provided on the low-pressure stage oil supply path 414.

[0023] The operation of the gas compressor 1 is input to the display and input device 701, and based on the input values, the control device 703 controls all electrical and electronic devices of the gas compressor 1. The control device 703 also receives input from various detectors inside the gas compressor and monitors, judges, and controls the operating status of the gas compressor based on a program set in advance in the storage device 702.

[0024] Antenna 704 is a wireless transceiver that transmits and receives values ​​detected by various detection devices built into the gas compressor 1 and information stored in the storage device 702 to an external server 802 via the communication network 801.

[0025] Viewers in remote locations (not shown in the diagram) can access information about the gas compressor stored on the external server 802 via various information terminals.

[0026] Figure 2 is a flowchart of the process for determining when to clean or replace the pre-filters for compressed air and cooling air, performed by the gas compressor 1 in Figure 1 in this embodiment. In this embodiment, the low-pressure stage compressor body 101 and the high-pressure stage compressor body 102 are fixed-speed machines in which the motor 103 is driven at a constant speed based on the power supply frequency, and the cooling fan 204 is also operated at a constant rotational speed based on the power supply frequency, and this explanation describes a case where this is fixed-speed control.

[0027] When the operator of the gas compressor 1 initiates operation from the display / input device 701, the motor 103 starts, driving the low-pressure stage compressor body 101 and the high-pressure stage compressor body 102, and the intake valve 301 opens. Air drawn in from the atmosphere passes through the compressed air pre-filter 600a and the intake filter 601, and with most of the dust removed, flows into the low-pressure stage compressor body 101, where it is compressed for the first stage. Thereafter, it flows along the flow direction shown in the system diagram in Figure 1, and finally, compressed air at a predetermined pressure is supplied to the compressed air demand destination from the discharge air path 405.

[0028] Furthermore, simultaneously with the start of the motor 103, the cooling fan 204 is also started, and air is drawn in from the outside as cooling air. After the cooling air pre-filter 600b is added to remove most of the dust, the air passes through the intercooler 201, aftercooler 202, and oil cooler 203, where it exchanges heat with the high-temperature fluid, and is then exhausted from the exhaust port 004a.

[0029] In step S101 of Figure 2, when the motor 103 starts and the suction valve 301 opens to begin drawing in air, if the suction pressure Ps (which is a negative value because it is a gauge pressure) detected by the suction pressure sensor 501 is greater than the preset suction pressure alarm value Ps0, then the process proceeds to step S103. If Ps ≤ Ps0, it means that the intake filter is clogged. In this case, the pressure ratio inside the compressor body increases, which can cause the discharge air temperature to become abnormally high and potentially lead to a malfunction. To prevent this, the process proceeds to step S102, where an alarm is promptly displayed on an external server 802 or an information terminal (not shown) remotely monitored via the display / input device 701 or communication network 801. This flowchart then concludes.

[0030] In step S103, if the cumulative operating time Hc from the last cleaning instruction to the present is an integer multiple of the predetermined judgment period H, proceed to step S104; otherwise, terminate this flowchart.

[0031] Next, in step S104 and beyond, the frequency of cleaning or replacing the pre-filter is determined. However, to maintain the performance and reliability of the gas compressor, it is preferable to clean or replace both the cooling air pre-filter and the compressed air pre-filter simultaneously, without distinguishing between them. Therefore, the average load factor R of the gas compressor and the average load factor Rf of the cooling fan may be compared, and the value of the larger load factor may be used to determine the frequency of cleaning or replacing the pre-filter. Alternatively, if the cooling fan 204 is operated at a constant rotational speed regardless of the operating state of the gas compressor 1 using fixed-speed control, the frequency of cleaning or replacing the pre-filter may be determined using only the average load factor R of the gas compressor. Accordingly, the following processing will be explained using the average load factor R of the gas compressor, but if the average load factor Rf of the cooling fan is used, R should be read as Rf during processing.

[0032] In step S104, if the average load factor R of the gas compressor satisfies the medium load factor determination value RM, proceed to step S106; otherwise, proceed to step S105.

[0033] Here, the average load factor R is defined as follows. That is, if the rotational speed of motor 103 is fixed speed, for example, if the operating cycle time T3 is a cycle in which one load operation and one no-load operation are performed, the current load factor Rc[%] is calculated as = load operation time T2 ÷ operating cycle time T3. Here, operating cycle time T3 = no-load operation time T1 + load operation time T2. However, T1, T2, and T3 refer to the respective times in the operating cycle immediately preceding the operating cycle in which the gas compressor is currently operating. The average load factor R can be obtained by summing this current load factor Rc for the number of load operations (= number of operating cycles) N from the last load factor determination to the present, and dividing this by N, and that is, the average load factor R can be expressed as average load factor R = ΣRc / N.

[0034] If it is determined in step S104 that R>RM and the process proceeds to step S105, a predetermined high-frequency cleaning cycle HH, for example 100 hours, is substituted for the pre-filter determination cycle H, and the process proceeds to step S109.

[0035] If it is determined in step S104 that R ≤ RM and the process proceeds to step S106, and the average load factor R satisfies R ≤ RL relative to the low load factor determination value RL, the process proceeds to step S108. Otherwise, the process proceeds to step S107.

[0036] In step S107, the normal cleaning cycle HM, for example 200 hours, is substituted for the pre-filter determination cycle H, and the process proceeds to step S109. If it is determined in step S106 that R ≤ RL and the process proceeds to step S108, the low-frequency cleaning cycle HL, for example 400 hours, is substituted for the pre-filter determination cycle H, and the process proceeds to step S109.

[0037] In step S109, the difference between the pre-filter determination period H, which was substituted in the step prior to step S109, and the cumulative operating time Hc from the last cleaning instruction to the present, H-Hc, is calculated. If H-Hc ≤ 0, that is, if the cumulative operating time Hc from the last cleaning instruction to the present exceeds the period (determination period H) for which the pre-filter should be cleaned, it is determined that it is time to clean the pre-filter, and the process proceeds to step S110, where a message recommending cleaning or replacing the pre-filter is displayed on the display / input device 701, and data recommending cleaning or replacing the pre-filter is sent to the server 802 via the communication network 801. After that, the process proceeds to step S111, where the cumulative operating time Hc from the last cleaning instruction to the present is initialized to 0, and this flowchart ends.

[0038] If step S109 does not satisfy H-Hc≦0, that is, if the cumulative operating time Hc from the last cleaning instruction to the present has not reached the judgment period H, this flowchart terminates.

[0039] According to the flowchart in Figure 2, the load factor of the gas compressor is related to the amount of air passing through the intake compressed air pre-filter 600a. When the average load factor R is higher than the medium load factor determination value RM, the amount of air passing through the compressed air pre-filter 600a increases, and the amount of dust collected by the compressed air pre-filter 600a increases proportionally. In this case, the recommended cleaning cycle is the high-frequency cleaning cycle HH, and it is determined that it is desirable to clean or replace the pre-filter at a faster interval than usual.

[0040] On the other hand, if the average load factor R is lower than the low load factor judgment value RL, the amount of dust collected by the compressed air pre-filter 600a will also decrease, so the cleaning frequency will be less frequent. Therefore, a low-frequency cleaning cycle HL will be selected, the pre-filter cleaning cycle will be longer, and the user will be able to reduce the number of times they have to clean the pre-filter.

[0041] As described above, according to this embodiment, it is possible to optimize the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air according to the type of gas compressor and the load factor. [Examples]

[0042] In this embodiment, we will describe an example of issuing instructions to clean or replace the pre-filter while taking into account changes in the input current of the cooling fan.

[0043] The system diagram showing the components of the gas compressor in this embodiment is omitted because, compared to the configuration in Figure 1, it includes an ammeter for measuring the input current of the cooling fan 204.

[0044] Figure 3 is a flowchart of the process for determining when to clean or replace the pre-filter in this embodiment. In Figure 3, the same processing steps as in Figure 2 are denoted by the same reference numerals, and their descriptions are omitted. The difference between Figure 3 and Figure 2 is the addition of step S201.

[0045] In the case of fixed-speed control where the cooling fan 204 is operated at a constant speed according to the power supply frequency, as clogging of the cooling air pre-filter 600b progresses, the amount of air drawn in through the cooling air intake port 3a decreases. As the amount of intake air decreases, the power consumption of the cooling fan decreases compared to when the clogging of the cooling air pre-filter 600b is minimal, and therefore the input current also decreases. For this reason, in step S201, a predetermined threshold Ith is set for the input current If of the cooling fan 204, and if the cooling fan input current If is less than the predetermined threshold Ith, it is determined that clogging of the cooling air pre-filter 600b has progressed to a considerable extent, and instructions for cleaning or replacing the cooling air pre-filter 600b, or both the cooling air pre-filter 600b and the compressed air pre-filter 600a, are displayed on the display / input device 701 to prompt the user to take attention and take action.

[0046] As described above, this embodiment has the added benefit of being able to determine in advance whether the cooling air prefilter 600b is clogged, in addition to the effects of the first embodiment. [Examples]

[0047] This embodiment describes a case where the cooling fan is driven by an inverter and its rotational speed is controlled at a variable speed.

[0048] Figure 4 is a system diagram showing the components of the gas compressor in this embodiment. In Figure 4, the same components as in Figure 1 are denoted by the same reference numerals, and their descriptions are omitted. In Figure 4, the difference from Figure 1 is that the control device 703 is equipped with a cooling fan inverter 703a, which is a variable speed control device for the cooling fan.

[0049] In this embodiment, the flowchart for determining the timing of cleaning or replacing the pre-filters for compressed air and cooling air performed by the gas compressor 1 in Figure 4 is the same as in Figure 2. However, in the case of a cooling fan that is inverter-driven and whose rotational speed is variable-speed controlled, the method for calculating the average load factor differs from that of a fixed-speed fan. As an example of how to calculate the average load factor for a variable-speed fan, in the case of an inverter-driven cooling fan, the current load factor Rfc = (load time T2 * current fan inverter frequency ffc [Hz]) ÷ (operating cycle time T3 * rated fan inverter frequency ffr [Hz]). The average load factor Rf [%] = ΣRfc / N is obtained by averaging this over the number of load cycles N from the last load factor determination to the last operating cycle.

[0050] As described above, according to this embodiment, similar to Embodiment 1, it is possible to optimize the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air according to the type of gas compressor and the load factor. [Examples]

[0051] In Example 2, an example was described in which instructions for cleaning or replacing the pre-filter were given considering changes in the cooling fan input current. However, in Example 2, the cooling fan 204 was controlled at a fixed speed, whereas if the cooling fan is controlled at a variable speed, for example, if the rotational speed of the cooling fan 204 is reduced during no-load operation compared to during load operation, the input current of the cooling fan 204 will also decrease due to the decrease in rotational speed. Therefore, simply determining the clogging state of the pre-filter based solely on the input current threshold is not necessarily an accurate judgment.

[0052] Therefore, this embodiment describes an example in which clogging of the cooling air pre-filter 600b can be determined in advance when the cooling fan is driven by an inverter and its rotation speed is variably controlled.

[0053] The system diagram showing the components of the gas compressor in this embodiment is the same as the configuration in Figure 4, but with the addition of an ammeter to measure the input current of the cooling fan inverter 703a. Therefore, the other components are the same and are omitted from the description.

[0054] Figure 5 shows the relationship between the output frequency of the cooling fan inverter and the inverter input current value in this embodiment. In Figure 5, the relationship between the output frequency ffc of the cooling fan inverter and the input current Iif of the cooling fan inverter is such that when the pre-filter is clogged, the input current Iif decreases for the same output frequency ffc compared to normal conditions.

[0055] Figure 6 is a flowchart of the process for determining when to clean or replace the pre-filter in this embodiment. In Figure 6, the same processing steps as in Figure 3 are denoted by the same reference numerals, and their explanations are omitted. The difference in Figure 6 from Figure 3 is that step S201 has been replaced with step S301.

[0056] In step S301 of Figure 6, the characteristics of the cooling fan inverter's output frequency fff and input current Iif, which are assumed in advance as shown in Figure 5, are determined. If the measured cooling fan inverter input current Iif is, for example, 60% or less of the predicted value Io of the inverter input current at a predetermined output frequency, it is determined that the cooling air pre-filter 600b is clogged, and instructions for cleaning or replacement are displayed on the display / input device 701 to alert the user and prompt action. Since the value such as 60% is related to the frequency of pre-filter clogging, it is desirable that the user adjust this parameter according to the actual installation environment of the gas compressor 1.

[0057] As described above, this embodiment has the added benefit of being able to determine in advance whether the cooling air prefilter 600b is clogged, in addition to the effects of the third embodiment. [Examples]

[0058] In this embodiment, we will describe a case where the gas compressor is a variable-speed machine whose motor rotation speed can be controlled by a motor inverter, which is a frequency converter, and the cooling fan is inverter-driven and its rotation speed is variable-speed controlled.

[0059] Figure 7 is a diagram showing the components of the gas compressor in this embodiment. In Figure 7, the same components as in Figure 4 are denoted by the same reference numerals, and their descriptions are omitted. In Figure 4, the difference is that the control device 703 is equipped with a motor inverter 703b, which is a variable speed control device, inside the control device 703.

[0060] In this embodiment, the flowchart for determining the timing of cleaning or replacing the pre-filters for compressed air and cooling air performed by the gas compressor 1 in Figure 7 is the same as in Figure 2. However, in the case of a variable-speed machine where the rotational speed of the motor can be controlled by the motor inverter 703b, the method for calculating the average load factor differs from that of a constant-speed machine. As an example of how to calculate the average load factor of a variable-speed machine, the rotational speed of the motor 103 is changed by changing the output frequency of the inverter so that the discharge air pressure remains constant during load operation. The current load factor Rc can be expressed as Rc[%]=(load time T2·current frequency fc[Hz])÷(operating cycle time T3·rated frequency fr[Hz]). Therefore, the average load factor R[%] of the variable-speed machine in the pre-filter cleaning determination cycle can be obtained as R[%]=ΣRc / (number of load cycles N[cycles]).

[0061] As described above, according to this embodiment, similar to embodiments 1 and 3, it is possible to optimize the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air according to the type of gas compressor and the load factor. [Examples]

[0062] In Example 5, the intake port 2a for compressed air and the intake port 3a for cooling air are separate and independent of each other. However, in this example, it is also possible to have a configuration in which the intake port 3a for cooling air serves the function of the intake port 2a for compressed air.

[0063] Figure 8 is a system diagram showing the components of the gas compressor in this embodiment. In Figure 8, components identical to those in Figure 7 are denoted by the same reference numerals, and their explanations are omitted. In Figure 8, the difference from Figure 7 is that there is no intake port 2a for compressed air, and the intake port 3a for cooling air also functions as the intake port 2a for compressed air. Also, there is no pre-filter 600a for compressed air, and the pre-filter 600b for cooling air also functions as the pre-filter 600a for compressed air.

[0064] Thus, in this embodiment, even with a configuration in which the cooling air intake 3a also serves as the compressed air intake 2a, it is possible to optimize the frequency of cleaning or replacing the pre-filter, which serves both compressed air and cooling air, according to the type of gas compressor and load factor, similar to Embodiment 5.

[0065] Furthermore, the configuration in which the cooling air intake port 3a also serves as the compressed air intake port 2a can be applied to each combination shown in Examples 1 to 3, such as whether the gas compressor is a fixed-speed or variable-speed machine, or whether the cooling fan is fixed-speed controlled or variable-speed controlled.

[0066] Although embodiments have been described above, the present invention is not limited to the embodiments described above and includes various modifications. For example, the gas compressor described in the embodiments above was described using an oil-free two-stage screw air compressor as an example, but it is not limited to this type of fluid machine, and may also be a single-stage compressor having only one compressor body, or it may be applicable to an oil-lubricated compressor in which lubricating oil is injected into the compression chamber inside the compressor body for the purpose of cooling and sealing the compressed air and lubricating the sliding surfaces of a pair of male and female screw rotors (not shown).

[0067] Furthermore, although the gas compressors in Examples 1 to 6 described above are air-cooled, even water-cooled compressors have an air intake 2a for compressed air, and if a small cooling fan is provided for ventilation inside the casing, or if a self-cooling fan is provided on the non-load side of the motor 103, an air intake 3a for cooling air, regardless of size, is often provided. Therefore, the above embodiments can also be applied to water-cooled compressors.

[0068] Furthermore, the compression method is not limited to the twin-screw type containing a pair of male and female screw rotors as in the above-described embodiment, but can also be applied to all positive displacement compressors such as single-screw types, tooth types, and reciprocating types, as well as centrifugal and axial-flow turbo compressors, which consist of one screw rotor and multiple gate rotors.

[0069] Furthermore, the embodiments described above are detailed explanations provided to facilitate understanding of the present invention, and are not necessarily limited to those comprising all the described configurations. It is also possible to replace parts of the configuration of one embodiment with those of another embodiment, and to add configurations from other embodiments to a given embodiment. Additionally, it is possible to add, delete, or replace parts of the configurations in each embodiment with those of other embodiments. [Explanation of Symbols]

[0070] 1: Gas compressor, 2a: Intake port, 2b: Intake duct, 3a: Cooling air intake port, 3b: Cooling air duct, 101: Low-pressure stage compressor body, 102: High-pressure stage compressor body, 103: Motor, 201: Intercooler, 202: Aftercooler, 204: Cooling fan, 600a: Pre-filter for compressed air, 600b: Pre-filter for cooling air, 601: Intake filter, 701: Display and input device, 702: Memory device, 703: Control device, 703a: For cooling fan Inverter, 703b: Motor inverter, Ps: Suction pressure, Ps0: Suction pressure alarm setting value, R: Average load factor of gas compressor, Rc: Current load factor of gas compressor, Rf: Average load factor of cooling fan, Rfc: Current load factor of cooling fan, RH: High load factor judgment value, RM: Medium load factor judgment value, RL: Low load factor judgment value, HH: High frequency cleaning cycle, HM: Normal cleaning cycle, HL: Low frequency cleaning cycle, Hc: Cumulative operating time from the last cleaning instruction to the present, H: Judgment cycle

Claims

1. A gas compressor comprising: a compressed air pre-filter for primary removal of dust at the compressed air intake port of the housing; an intake filter for further secondary removal of dust; at least one compressor body that draws in and compresses air through the intake filter and intake passage; a motor that drives the compressor body; an air cooler for cooling the compressed air; a cooling fan that passes cooling air to the air cooler; a cooling air intake port that draws in cooling air from the outside air by the cooling fan; a cooling air pre-filter provided at the cooling air intake port; and a control device that controls the operation of the compressor, The control device is characterized in that it determines the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air based on the load factor, which is an indicator of the operating state, for a gas compressor.

2. In the gas compressor according to claim 1, The compressor body is a fixed-speed machine, If we assume that the operating cycle time for the compressor body to perform one load operation and one no-load operation is T3, the no-load operation time is T1, the load operation time is T2, the number of operating cycles is N, T3 = T1 + T2, the current load factor Rc = T2 ÷ T3, and the average load factor R = ΣRc / N, then, The control device is characterized by calculating the average load factor R as the load factor, and determining the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air by comparing the average load factor R with the load factor determination value.

3. In the gas compressor according to claim 2, The cooling fan has fixed speed control. The control device is characterized by calculating the average load factor Rf of the cooling fan, comparing the average load factor R of the compressor body with the average load factor Rf of the cooling fan, and using the value of the larger load factor to determine the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air.

4. In the gas compressor according to claim 1, The cooling fan has fixed speed control. An ammeter for measuring the input current of the cooling fan, Having a display device, The control device is characterized in that, when the input current of the cooling fan is less than a predetermined threshold, it displays an instruction on the display device to clean or replace the pre-filter for compressed air and the pre-filter for cooling air.

5. In the gas compressor according to claim 3, The cooling fan is variable speed controlled, The cooling fan has a variable speed control device that controls the cooling fan at a variable speed, Let T3 be the operating cycle time for performing one load operation and one unload operation of the cooling fan, T1 be the unload operation time, T2 be the load operation time, T3 = T1 + T2, ffc be the current frequency of the variable speed control device, ffr be the rated frequency of the variable speed control device, N be the number of operating cycles, and Rfc = (T2 * ffc) ÷ (T3 * ffr), then The control device is characterized by calculating Rf = ΣRfc / N as the average load factor Rf of the cooling fan.

6. In the gas compressor according to claim 1, The cooling fan is variable speed controlled, A variable speed control device for controlling the cooling fan at a variable speed, An ammeter for measuring the input current of the variable speed control device, Having a display device, The control device is characterized in that, based on the relationship between the output frequency of the variable speed control device and the corresponding predicted value of the input current estimated in advance, if the input current measured by the ammeter is less than the predicted value of the input current by a predetermined amount, the control device displays an instruction on the display device to clean or replace the pre-filter for compressed air and the pre-filter for cooling air.

7. In the gas compressor according to claim 1, The compressor body is a variable speed machine, The compressor body has a variable speed control device that controls the speed of the compressor body, Let T3 be the operating cycle time for the compressor body to perform one load operation and one no-load operation, T1 be the no-load operation time, T2 be the load operation time, T3 = T1 + T2, the current frequency of the variable speed control device be fc [Hz], the rated frequency of the variable speed control device be fr [Hz], the number of operating cycles be N, the current load factor Rc = (T2 * fc) ÷ (T3 * fr), and the average load factor R = ΣRc / N. The control device is characterized by calculating the average load factor R as the load factor, and determining the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air by comparing the average load factor R with the load factor determination value.

8. In the gas compressor according to claim 1, A gas compressor characterized in that, instead of the compressed air intake port and the compressed air prefilter, the cooling air intake port and the cooling air prefilter perform the same function.

9. In the gas compressor according to claim 1, It has a suction pressure sensor, The control device calculates the cumulative pressure loss, which is the cumulative value of the suction pressure detected by the suction pressure sensor over the operating time, and determines the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air from the amount of change in the cumulative pressure loss per predetermined time and the average load factor of the gas compressor.

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