Gas compressor

Abstract

The present invention provides a gas compressor, with the aim of optimizing the frequency of cleaning or replacement of a compressed air pre-filter and a cooling air pre-filter. To achieve the above aim, the gas compressor is provided with a compressed air pre-filter configured at a compressed air suction port of a casing for primary removal of dust, and further provided with a suction filter for secondary removal of dust; at least one compressor body for sucking in air via the suction filter and a suction passage to compress the air; a motor for driving the compressor body; an air cooler for cooling the compressed air; a cooling fan for passing cooling air through the air cooler; a cooling air suction port for sucking in air from the outside by the cooling fan; a cooling air pre-filter provided at the cooling air suction port; and a control device for controlling the operation of the compressor, the control device determining the frequency of cleaning or replacement of the compressed air pre-filter and the cooling air pre-filter according to a load rate as an index of the operating state.

Description

Technical Field

[0001] This invention relates to gas compressors. Background Technology

[0002] Gas compressors, such as those that draw in and compress air as a gas, include one or more intake filters for filtering air flowing into the compressor body, which has a reciprocating or rotating body inside. Furthermore, since the compressor body is housed in a casing designed for sound insulation and weather resistance, an external gas filter is sometimes installed at the intake port of the casing to remove dust and other particles from the external gas to a certain extent. Techniques for drawing clean air into the compressor body using multi-stage filters are known. Patent Document 1 is an example of such prior art.

[0003] Patent document 1 discloses a system for predicting the rate of degradation of components of a turbomachinery using state-based monitoring. The system uses a compressor degradation prediction model that provides a function of compressor performance based on sensor data, the degradation rate of one or more filters, or some combination thereof, to predict the rate of degradation of the compressor. Based on the predicted rate of degradation, one or more preventive actions are performed.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-44546 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In Patent Document 1, the filter deterioration prediction model for calculating the filter deterioration rate can predict that the amount of air drawn through the filter and the load operation time of the compressor also have a significant impact on the prediction model. However, it does not specifically mention the relationship with the load rate, which is an indicator of the compressor's operating status, calculated based on parameters such as the compressor's drive method related to the air volume, the ratio of the opening time to the operating time of the compressor's suction valve, or the rotational speed of the motor or prime mover driving the compressor body.

[0009] Furthermore, Patent Document 1 does not specifically describe a method for determining the cleaning or replacement period of the pre-filter when a structure is adopted in which a pre-filter for removing dust from the atmosphere is disposed on the upstream side of the filter chamber.

[0010] Furthermore, the filter in Patent Document 1 is a mechanism for filtering the air drawn into the main body of the turbo compressor. In the case of a compressor with an air-cooled cooler for cooling compressed air, a cooling fan is provided. Sometimes a pre-filter for the cooler is provided at the air inlet of the cooling fan to remove dust once. However, no research is mentioned on the filter deterioration prediction model for the aforementioned pre-filter for the cooler.

[0011] The object of the present invention is to optimize the cleaning and replacement frequency of pre-filters for compressed air and pre-filters for cooling air in view of the above-mentioned problems.

[0012] Technical solutions for solving the problem

[0013] One example of this invention is a gas compressor, which has a pre-filter for compressed air that removes dust once at the compressed air intake port of the housing, and an intake filter that further removes dust a second time; at least one compressor body that draws in and compresses air through the intake filter and intake passage; an electric motor that drives the compressor body; an air cooler for cooling the compressed air; a cooling fan that passes cooling air through the air cooler; a cooling air intake port that draws in external air using the cooling fan; a cooling air pre-filter provided at the cooling air intake port; and a control device for controlling the operation of the compressor. In this gas compressor, the control device determines the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air based on the load rate, which is an indicator of the operating state.

[0014] Invention Effects

[0015] According to the present invention, it is possible to achieve the effect of optimizing the cleaning and replacement frequency of the pre-filter for compressed air and the pre-filter for cooling air. Attached Figure Description

[0016] Figure 1 This is a system diagram showing the components of the gas compressor in Example 1.

[0017] Figure 2 This is a flowchart illustrating the process for determining the timing of cleaning or replacement of the pre-filters for compressed air and cooling air in Example 1.

[0018] Figure 3 This is a flowchart illustrating the process for determining the timing of cleaning or replacing the pre-filter in Example 2.

[0019] Figure 4 This is a system diagram showing the components of the gas compressor in Example 3.

[0020] Figure 5This is a graph showing the relationship between the output frequency of the inverter for the cooling fan in Example 4 and the input current of the inverter.

[0021] Figure 6 This is a flowchart illustrating the process for determining the timing of cleaning or replacing the pre-filter in Example 4.

[0022] Figure 7 This is a system diagram showing the components of the gas compressor in Example 5.

[0023] Figure 8 This is a system diagram showing the components of the gas compressor in Example 6.

[0024] Figure 9 This is a flowchart illustrating the process for determining the timing of cleaning or replacing the pre-filter in Example 7.

[0025] Figure 10 This is a graph showing the pressure loss curve and the cumulative pressure loss curve in Example 7.

[0026] Figure 11 This is a graph showing the pressure loss over operating time in Example 7.

[0027] Figure 12 This is a graph showing the cumulative pressure loss over operating time in Example 7.

[0028] Figure 13 This is a graph showing the slope of the cumulative pressure loss curve over operating time in Example 7.

[0029] Figure 14 This is a flowchart illustrating the process for determining the timing of cleaning or replacing the pre-filter in Example 8.

[0030] Figure 15 This is a flowchart illustrating the process for determining the timing of cleaning or replacing the pre-filter in Example 9. Detailed Implementation

[0031] The embodiments of the present invention are described below using the accompanying drawings.

[0032] Example 1

[0033] In this embodiment, an air-cooled, oil-free two-stage screw air compressor is used as an example for illustration.

[0034] Figure 1 This is a system diagram showing the constituent elements of the gas compressor in this embodiment. Figure 1 In the middle, the gas compressor 1 is a structure that compresses air in two stages. It draws in air by driving the low-pressure stage compressor body 101 and the high-pressure stage compressor body 102, and then compresses and discharges it.

[0035] Figure 1 In this design, the low-pressure compressor body 101, the high-pressure compressor body 102, the electric motor 103, and the oil pump 105 are fixed to the speed increaser housing 104. A low-pressure stage pinion 107 is mounted at the front end of the drive shaft of the low-pressure compressor body 101, and a high-pressure stage pinion 108 is mounted at the front end of the drive shaft of the high-pressure compressor body 102. For the drive shaft of the electric motor 103, a bull gear 106 and an oil pump pinion 109 are engaged from the root side of the drive shaft. The bull gear 106 meshes with the low-pressure stage pinion 107 and the high-pressure stage pinion 108. In addition, the oil pump pinion 109 meshes with the oil pump gear 110. Driven by the electric motor 103, the bull gear 106 rotates, thereby driving the low-pressure compressor body 101, the high-pressure compressor body 102, and the oil pump 105.

[0036] When operation begins, the low-pressure stage compressor body 101 and the high-pressure stage compressor body 102 are driven by the electric motor 103, and the suction valve 301 is opened. Air is drawn in from the atmosphere through the compressed air pre-filter 600a provided in the suction port 2a of the gas compressor 1 housing. Dust is separated from the drawn-in air at first. The air passes through the suction duct 2b, and the dust is further separated at second time in the suction filter 601. The clean air flows into the low-pressure stage compressor body 101 through the suction air passage 401, which serves as the suction passage, and the suction valve 301.

[0037] The low-pressure stage compressor body 101 compresses air to a specified pressure. The compressed air then flows through the low-pressure stage discharge air passage 402 and into the intercooler 201. The intercooler 201 is an air-cooled heat exchanger, i.e., an air cooler, which cools the high-temperature compressed air by allowing cooling air generated by the cooling fan 204 to pass through it. The compressed air cooled in the intercooler 201 flows through the high-pressure stage intake air passage 403 and into the high-pressure stage compressor body 102, where it is compressed to a higher pressure. The high-pressure compressed air discharged from the high-pressure stage compressor body 102 flows through the high-pressure stage discharge air passage 404 and into the aftercooler 202. The aftercooler 202 is also an air-cooled heat exchanger, i.e., an air cooler, similar to the intercooler 201, which cools the compressed air with cooling air from the cooling fan 204. The compressed air cooled in the aftercooler 202 then flows through the discharge air passage 405 and is supplied to the demand side of compressed air.

[0038] The pre-filter 600a for compressed air generally has a lower filtration accuracy compared to the intake filter 601, aiming to remove larger foreign objects and dust in one pass, thereby delaying the clogging of the intake filter 601. Similarly, by installing a pre-filter 600b for cooling air at the intake port 3a, larger foreign objects and dust are also removed. Therefore, the air drawn in by the cooling fan 204 through the cooling air intake port 3a and the cooling air duct 3b is relatively clean, reducing the clogging of the cooling fins of the air-cooled intercooler 201, aftercooler 202, and oil cooler 203 by dust. After heat exchange with the high-temperature compressed air and lubricating oil through the intercooler 201, aftercooler 202, and oil cooler 203, the cooling air is discharged to the atmosphere through the exhaust port 4a via the fan duct 4b.

[0039] In the low-pressure stage compressor body 101, the high-pressure stage compressor body 102, the speed increaser housing 104, and the oil pump 105, there are built-in bearings supporting rotating bodies (not shown). In addition, since the large gear 106, the low-pressure stage pinion 107, the high-pressure stage pinion 108, the oil pump pinion 109, and the oil pump gear 110 are meshing and rotating at the same time, these mechanical parts generally require lubricant. In this embodiment, the lubricating oil is stored in the lower part of the speed increaser housing 104.

[0040] When the oil pump 105 is driven by the electric motor 103, lubricating oil is drawn in from the lower part of the speed increaser housing 104, flows through the suction oil pipe 411, enters the oil pump 105, and is discharged. The lubricating oil discharged from the oil pump 105 passes through the discharge oil passage 412, is cooled by the oil cooler 203 (which is an air-cooled heat exchanger), and is then sent to the main oil supply passage 413. An oil filter 603 is installed in the middle of the main oil supply passage 413. In addition, the main oil supply passage 413 branches into a low-pressure stage oil supply passage 414, a high-pressure stage oil supply passage 415, and a speed increaser oil supply passage 416, supplying lubricating oil to the low-pressure stage compressor body 101, the high-pressure stage compressor body 102, and the speed increaser housing 104.

[0041] In the compressed air passage, there is a venting device for releasing the compressed air remaining in the compressed air passage to the outside when the gas compressor is operating without load or when it stops operating. Vent valves 302 and 303 release the compressed air from the discharge side of the high-pressure stage compressor body 102 to the outside of the air passage up to the check valve 304.

[0042] Various detectors are installed throughout the gas compressor 1 to determine whether the gas compressor is operating normally or to control its operation by the control device 703. For example, an intake pressure sensor 501 is provided in the intake air passage 401; a low-pressure stage exhaust air temperature sensor 505 is provided in the low-pressure stage exhaust air passage 402; a high-pressure stage intake air pressure sensor 502 and a high-pressure stage intake air temperature sensor 506 are provided in the high-pressure stage intake air passage 403; a high-pressure stage exhaust air temperature sensor 507 is provided in the high-pressure stage exhaust air passage 404; and an exhaust air pressure sensor 503 is provided in the exhaust air passage 405. Additionally, an oil pressure sensor 504 and an oil temperature sensor 508 are provided in the low-pressure stage oil supply passage 414.

[0043] The operation of the gas compressor 1 is input to the display and input device 701, and the control device 703 controls all the electrical and electronic devices of the gas compressor 1 based on the input value. In addition, the control device 703 receives input from various detectors inside the gas compressor and monitors and judges the operating status of the gas compressor based on a program preset in the storage device 702 to perform control.

[0044] Antenna 704 is a wireless transmission and reception device used to transmit and receive values ​​detected by various detection machines built into the gas compressor 1 and information stored in storage device 702 to an external server 802 via communication network 801.

[0045] Viewers at remote locations (not shown) can access information about the gas compressor stored on an external server 802 via various information terminals.

[0046] Figure 2 This is in this embodiment. Figure 1 The flowchart illustrates the process for determining when to clean or replace the pre-filters for compressed air and cooling air in the gas compressor 1. Furthermore, this embodiment explains that the low-pressure stage compressor body 101 and the high-pressure stage compressor body 102 are constant-speed machines driven by the motor 103 at a certain speed based on the power supply frequency, and the cooling fan 204 also operates at a constant speed based on the power supply frequency.

[0047] When the operator of gas compressor 1 starts operation using the display and input device 701, the motor 103 starts, driving the low-pressure stage compressor body 101 and the high-pressure stage compressor body 102. The suction valve 301 opens, and air drawn in from the atmosphere, having passed through the pre-filter 600a and suction filter 601 to remove dust, flows into the low-pressure stage compressor body 101 for the first stage of compression. Thereafter, the air continues to compress... Figure 1The system flows in the direction shown in the diagram, and eventually becomes compressed air at a specified pressure, which is supplied to the compressed air demander from the exhaust air passage 405.

[0048] In addition, at the same time as the motor 103 starts, the cooling fan 204 also starts. The air, as the cooling wind from the outside gas, passes through the cooling air pre-filter 600b to remove most of the dust, and then passes through the intercooler 201, aftercooler 202, and oil cooler 203 to exchange heat with the high-temperature fluid before being exhausted from the exhaust port 4a.

[0049] Figure 2 In step S101, when the motor 103 starts and the suction valve 301 opens to begin drawing in air, if the suction pressure Ps detected by the suction pressure sensor 501 (which is a gauge pressure and therefore a negative value) is greater than the preset suction pressure alarm value Ps0, the process proceeds to step S103. Conversely, if Ps ≤ Ps0, it indicates that the suction filter is clogged. In this case, there is a possibility that the exhaust air temperature may become abnormally high due to an increased pressure ratio inside the compressor body, potentially causing a malfunction. Therefore, to prevent this, the process proceeds to step S102, where an alarm is quickly displayed via the display and input device 701, the communication network 801 to an external server 802, or via the server 802 to an information terminal (not shown) that is being remotely monitored. Then, the process ends.

[0050] In step S103, if the cumulative operating time Hc from the final cleaning instruction to the current time is an integer multiple of the specified judgment period H, proceed to step S104; otherwise, end the process.

[0051] Next, after step S104, the frequency of cleaning or replacing the pre-filter is determined. To maintain the performance and reliability of the gas compressor, it is preferable that the cleaning or replacement of the pre-filter is performed simultaneously for both the cooling air pre-filter and the compressed air pre-filter. Therefore, the average load rate R of the gas compressor and the average load rate Rf of the cooling fan can be compared, and the value of the larger load rate can be used to determine the frequency of cleaning or replacing the pre-filter. In the case of constant speed control where the cooling fan 204 always operates at a certain speed regardless of the operating state of the gas compressor 1, the frequency of cleaning or replacing the pre-filter can also be determined solely based on the average load rate R of the gas compressor. Therefore, in subsequent processing, the process will be explained based on the average load rate R of the gas compressor. When using the average load rate Rf of the cooling fan, R will be replaced with Rf for processing.

[0052] In step S104, if the average load rate R of the gas compressor is relative to the medium load rate judgment value RM and satisfies R≤RM, proceed to step S106; otherwise, proceed to step S105.

[0053] Here, the average load rate R is defined as follows. Specifically, assuming the motor 103 operates at a constant speed, let the cycle time T3 be the time between one load operation and one no-load operation. The current load rate Rc[%] is calculated as: Load operation time T2 ÷ Cycle time T3. Here, cycle time T3 = No-load operation time T1 + Load operation time T2. T1, T2, and T3 refer to the times in the previous cycle of the current gas compressor's operating cycle. The current load rate Rc is calculated by summing the N load operations (= number of cycles) from the last load rate up to the current point, dividing by N, and thus obtaining the average load rate R, which can be expressed as: Average load rate R = ∑Rc / N.

[0054] If in step S104 it is determined that R>RM and proceeds to step S105, the determination period H of the pre-filter is substituted with the specified high-frequency cleaning period HH, such as 100 hours, and the process proceeds to step S109.

[0055] If in step S104 it is determined that R≤RM and proceeds to step S106, then if the average load rate R satisfies R≤RL relative to the low load rate judgment value RL, proceed to step S108. If this condition is not met, proceed to step S107.

[0056] In step S107, the judgment period H of the pre-filter is substituted into the normal cleaning period HM, for example, 200 hours, and the process proceeds to step S109.

[0057] If in step S106 it is determined that R≤RL and proceeds to step S108, the determination period H of the pre-filter is substituted with the low-frequency cleaning period HL, for example 400 hours, and proceeds to step S109.

[0058] In step S109, relative to the judgment period H of the pre-filter substituted in the steps preceding S109, the difference H-Hc between the final cleaning instruction and the current cumulative operating time is calculated. If H-Hc ≤ 0, that is, because the cumulative operating time Hc between the final cleaning instruction and the current time exceeds the period (judgment period H) during which the pre-filter should be cleaned, it is determined that the period for cleaning the pre-filter has arrived, and the process proceeds to step S110. A message recommending cleaning or replacing the pre-filter is displayed on the display and input device 701, and data recommending cleaning or replacing the pre-filter is sent to the server 802 via the communication network 801. Afterwards, the process proceeds to step S111, where the cumulative operating time Hc between the final cleaning instruction and the current time is initialized to 0, and the process ends.

[0059] If the condition H-Hc≤0 is not met in step S109, that is, if the cumulative operating time Hc from the final cleaning instruction to the current time has not reached the judgment cycle H, the process ends.

[0060] according to Figure 2 The flowchart shows that the load rate of the gas compressor is related to the amount of air passing through the pre-filter 600a for compressed air intake. When the average load rate R is higher than the medium load rate RM, the amount of air passing through the pre-filter 600a for compressed air increases, and the amount of dust captured by the pre-filter 600a for compressed air also increases proportionally. Therefore, in this case, it is recommended to select a high-frequency cleaning cycle HH, indicating that the pre-filter needs to be cleaned or replaced at a faster cycle than usual.

[0061] On the other hand, when the average load rate R is lower than the low load rate judgment value RL, the amount of dust captured by the pre-filter 600a with compressed air is also reduced, so the cleaning frequency can be less. Therefore, a low frequency cleaning cycle HL is selected, the pre-filter cleaning cycle becomes longer, and the number of times the pre-filter needs to be cleaned can be reduced for the user.

[0062] As described above, according to this embodiment, the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air can be optimized in accordance with the type and load rate of the gas compressor.

[0063] Example 2

[0064] This embodiment illustrates an example of instructing the pre-filter to be cleaned or replaced taking into account changes in the input current of the cooling fan.

[0065] The system diagram showing the components of the gas compressor in this embodiment is for... Figure 1 The structure includes a current meter for measuring the input current of the cooling fan 204; the system diagram is omitted.

[0066] Figure 3 This is a flowchart illustrating the process for determining when to clean or replace the pre-filter in this embodiment. Figure 3 In, with Figure 2 The same processing steps are accompanied by the same symbols, and their descriptions are omitted. Figure 3 In, with Figure 2 The difference is that step S201 has been added.

[0067] When the cooling fan 204 operates at a constant speed based on the power supply frequency, and the pre-filter 600b for cooling air becomes clogged, the amount of air drawn in through the cooling air intake 3a decreases. As the amount of air drawn in decreases, the power consumption of the cooling fan decreases compared to when the pre-filter 600b is less clogged, and therefore the input current also decreases. Therefore, in step S201, a predetermined threshold Ith is set for the input current If of the cooling fan 204. If the cooling fan input current If is less than the predetermined threshold Ith, it is determined that the clog of the pre-filter 600b has progressed to a certain extent. An instruction to clean or replace the pre-filter 600b, or both the pre-filter 600b and the compressed air pre-filter 600a, is displayed on the display / input device 701 to alert the user and prompt them to take appropriate action.

[0068] As described above, according to this embodiment, in addition to the effects of Embodiment 1, it also has the effect of being able to detect the blockage of the pre-filter 600b for cooling air in advance.

[0069] Example 3

[0070] This embodiment illustrates the case of inverter-driven cooling fan and variable speed control of its rotation speed.

[0071] Figure 4 This is a system diagram showing the constituent elements of the gas compressor in this embodiment. Figure 4 In, with Figure 1 The same structures are labeled with the same reference numerals in the accompanying drawings, and their descriptions are omitted. Figure 4 In, with Figure 1 The difference lies in the fact that the control device 703 has a cooling fan inverter 703a inside, which serves as a speed control device for the cooling fan.

[0072] In this embodiment Figure 4 The process flow diagram for determining the timing of cleaning or replacement of the pre-filters for compressed air and cooling air in gas compressor 1 is shown below. Figure 2The calculation method for the average load rate differs from that for a constant-speed cooling fan, but it is the same for a cooling fan that is driven by an inverter and has variable speed control. An example of the variable-speed average load rate calculation method is shown below. For an inverter-driven cooling fan, the current load rate Rfc = (load time T2 · current fan inverter frequency ffc [Hz]) ÷ (operation cycle time T3 · rated fan inverter frequency frr [Hz]). The average load rate Rf[%] is obtained by averaging this over N load cycles from the last load rate to the last operation cycle, resulting in Rf[%] = ∑Rfc / N.

[0073] As described above, according to this embodiment, similar to Embodiment 1, the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air can be optimized in accordance with the type and load rate of the gas compressor.

[0074] Example 4

[0075] Example 2 illustrates an example of instructing the pre-filter to be cleaned or replaced considering changes in the cooling fan input current. However, in Example 2, the cooling fan 204 is controlled at a constant speed. In contrast, when the cooling fan is controlled at a variable speed, for example, when the speed of the cooling fan 204 is reduced during no-load operation compared to when it is under load, the input current of the cooling fan 204 also decreases due to the reduced speed. Therefore, simply using the threshold value of the input current to determine the clogging status of the pre-filter may not yield an accurate assessment.

[0076] Therefore, in this embodiment, an example is described where the blockage of the pre-filter 600b for cooling air can be detected in advance when the cooling fan is driven by an inverter and its speed is controlled by a variable speed.

[0077] The system diagram showing the components of the gas compressor in this embodiment is for... Figure 4 The structure is the same as that of the current meter for measuring the input current of the inverter 703a for the cooling fan. Therefore, its description is omitted.

[0078] Figure 5 This is a graph showing the relationship between the output frequency of the inverter for the cooling fan in this embodiment and the inverter input current value. Figure 5 Regarding the relationship between the output frequency fffc of the inverter for cooling fans and the input current Iif of the inverter for cooling fans, when the pre-filter is clogged, the input current Iif decreases relative to the same output frequency fffc compared to the normal state.

[0079] Figure 6 This is a flowchart illustrating the process for determining when to clean or replace the pre-filter in this embodiment. Figure 6In, with Figure 3 The same processing steps are labeled with the same reference numerals, and their descriptions are omitted. Figure 6 In, with Figure 3 The difference is that step S201 is replaced with step S301.

[0080] Figure 6 In step S301, prior knowledge Figure 5 The characteristics of the output frequency fc and input current Iif of the inverter for the cooling fan, as shown in the diagram, indicate that if the predicted value Io of the inverter input current at the specified output frequency is less than, for example, 60%, the measured input current Iif is blocked. An instruction to clean or replace the filter 600b is then displayed on the display / input device 701 to alert the user. Furthermore, values ​​such as 60% are related to the frequency of filter blockage; therefore, it is preferable to set a parameter that the user can adjust according to the actual operating environment of the gas compressor 1.

[0081] As described above, according to this embodiment, in addition to the effects of Embodiment 3, it also has the effect of being able to detect the blockage of the pre-filter 600b for cooling air in advance.

[0082] Example 5

[0083] In this embodiment, the gas compressor is described as a variable speed motor that can control the speed of the motor by using an inverter for the motor as a frequency conversion device, and the speed of the cooling fan is controlled by variable speed by inverter drive.

[0084] Figure 7 This is a system diagram showing the constituent elements of the gas compressor in this embodiment. Figure 7 In, with Figure 4 The same structures are labeled with the same reference numerals, and their descriptions are omitted. Figure 4 In, with Figure 4 The difference is that the control device 703 has an inverter 703b for the motor that serves as a speed control device inside the control device 703.

[0085] In this embodiment Figure 7 The process flow diagram for determining the timing of cleaning or replacement of the pre-filters for compressed air and cooling air performed by gas compressor 1 is as follows: Figure 2The calculation method for the average load rate differs from that of a constant-speed motor in the case of a variable-speed motor where the motor speed can be controlled using the motor inverter 703b. An example of the calculation method for the average load rate of the variable-speed motor is shown, where the inverter's output frequency is varied by changing the motor speed of the motor 103 while maintaining a constant exhaust air pressure during load operation. The current load rate Rc can be expressed as Rc[%] = (load time T2 · current frequency fc[Hz]) ÷ (operation cycle time T3 · rated frequency fr[Hz]). Therefore, the average load rate R[%] of the variable-speed motor during the pre-filter cleaning judgment cycle is calculated as ∑Rc / (load times N[times]).

[0086] As described above, according to this embodiment, similar to Embodiments 1 and 3, the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air can be optimized in accordance with the type and load rate of the gas compressor.

[0087] Example 6

[0088] In Example 5, the intake port 2a for compressed air and the intake port 3a for cooling air are independent. In this example, we will describe a structure in which the intake port 3a for cooling air can replace the intake port 2a for compressed air and perform the same function.

[0089] Figure 8 This is a system diagram showing the constituent elements of the gas compressor in this embodiment. Figure 8 In, with Figure 7 The same structures are labeled with the same reference numerals, and their descriptions are omitted. Figure 8 In, with Figure 7 The difference is that it does not have an air intake port 2a for compressed air, while the air intake port 3a for cooling air also functions as the air intake port 2a for compressed air. Additionally, it does not have a pre-filter 600a for compressed air, while the pre-filter 600b for cooling air also functions as the pre-filter 600a for compressed air.

[0090] Thus, in this embodiment, the structure in which the cooling air intake 3a also serves as the compressed air intake 2a is the same as in Embodiment 5, which allows for the optimization of the frequency of cleaning or replacing the pre-filter used for both compressed air and cooling air in accordance with the type and load rate of the gas compressor.

[0091] In addition, the structure of the cooling air intake 3a can also be used as the intake 2a for compressed air, as shown in Examples 1 to 3, in various combinations where the gas compressor is a constant speed machine or a variable speed machine, or the cooling fan is a constant speed control or a variable speed control.

[0092] Example 7

[0093] In this embodiment, compared to Example 1, the suction pressure Ps is considered to be the pressure loss (pressure drop) relative to atmospheric pressure. The absolute value of the suction pressure (a negative value with atmospheric pressure as the zero reference) is taken as the pressure loss δp. The cumulative pressure loss S is calculated by summing these values ​​over the operating time. Based on the combination of the change in cumulative pressure loss over each specified time, i.e., the slope ΔS of the cumulative pressure loss curve, and the average load rate R, the degree of clogging of the pre-filter is inferred, thus enabling the method of increasing or decreasing the judgment cycle.

[0094] Figure 9 This is in this embodiment. Figure 1 The process flow diagram shows the timing for cleaning or replacing the pre-filters used by the gas compressor 1 for compressed air and cooling air. Figure 9 In, relative to Figure 2 Instead of steps S104 to S109, the following steps are added: Step S113, which determines whether the relationship between (ΔS / Hn) < (ΔSn / Hn) holds true in the slope of the cumulative pressure loss curve ΔS / H, the slope of the cumulative pressure loss curve at the time of the current determination, and the slope of the cumulative pressure loss curve at the time of the previous determination (ΔSn-1 / Hn-1); Step S115, which determines whether (ΔSn / Hn) < (ΔSn-1 / Hn-1) holds true if Step S113 does not hold true; and Step S115, which determines whether (ΔSn / Hn) < (ΔSn-1 / Hn-1) holds true if Step S115 does not hold true. Step S119: Checking if S1 / H1) < (ΔSn / Hn); Steps S114 and S118: Checking if the relationship between average load rate R and medium load rate judgment value RM is true; Steps S116 and S120: Checking if the relationship between average load rate R and low load rate judgment value RL is true; Steps S123 and S122: Multiplying the judgment period Hn by a reduction coefficient α1 or α2 (where α2 < α1 < 1) and substituting the new judgment period Hn; Steps S117, S124, and S126: Maintaining the current judgment period Hn; Steps S125 and S121: Multiplying the judgment period Hn by an increase coefficient β1 or β2 (where 1 < β1 < β2) and substituting the new judgment period Hn; Substituting... Figure 2The steps are as follows: S109, S127 (determining whether the judgment period Hn is below the lower limit judgment period HLL); S128 (substituting the lower limit judgment period HLL into the judgment period Hn if the above step S127 is true); S129 (determining whether the judgment period Hn is above the upper limit judgment period HHH); and S130 (substituting the upper limit judgment period HHH into the judgment period Hn if the above step S129 is true).

[0095] Figure 10 This is a graph of the pressure loss curve and the cumulative pressure loss curve when the horizontal axis is the operating time, the left vertical axis is the pressure loss δp, and the right vertical axis is the cumulative pressure loss S. Figure 10 In the case of a compressor with only a suction filter and a constant load rate, for example, without a pre-filter, the pressure loss curve 900 is a step-like curve (because it is a numerical value). The pressure loss δp begins to rise from approximately 80% of the operating time when a suction filter blockage alarm (the right end of the curve) is triggered, and then increases sharply within a short period, triggering another suction filter blockage alarm. On the other hand, with a pre-filter, the pressure loss curve 910 shows a short rise in pressure loss δp when pre-filter blockage has developed, followed by a decrease when the pre-filter is cleaned or replaced. A peak in pressure loss due to pre-filter blockage and cleaning can be observed. However, besides pre-filter and suction filter blockage, the pressure loss δp also changes accordingly with the compressor load rate, and the change in compressor load rate increases and decreases faster and more dramatically than the progression of filter blockage. Therefore, the instantaneous pressure loss δp is difficult to use for judging pre-filter blockage. Therefore, a cumulative pressure loss curve is calculated, which accumulates the measured pressure loss δp as a function of operating time t.

[0096] Figure 10 In the curve 960, which has a pre-filter, the cumulative pressure loss is further increased because the pressure loss corresponding to the pre-filter blockage is added, compared to the cumulative pressure loss curve 950 without a pre-filter. Therefore, the cumulative pressure loss of the curve 960 with a pre-filter is greater than that of the curve 950 without a pre-filter.

[0097] Figure 11 This is a graph representing the pressure loss δp relative to the operating time t in this embodiment. The cumulative pressure loss from the operating time 0 to the operating time tn of the nth judgment is Sn = ∑(δpn). Here, the difference between the operating time tn-1 of the (n-1)th judgment and the operating time tn of the nth judgment is the judgment period Hn, and let the increase in the cumulative pressure loss Sn in the judgment period Hn be ΔSn. Figure 11 In this context, the increase in cumulative pressure loss ΔSn from the (n-1)th judgment to the nth judgment is equal to the area enclosed by the curves of operating time tn, operating time tn-1, and pressure loss δp.

[0098] Figure 12 This is a graph showing the cumulative pressure loss S over operating time t in this embodiment, with the horizontal axis representing operating time and... Figure 11 correspond. Figure 12 In the curve 970, the cumulative pressure loss curve always increases to the right, and the magnitude of its slope varies depending on the degree of clogging of the pre-filter and the compressor load rate. Here, the increase in cumulative pressure loss ΔSn (=Sn-(Sn-1)) in the judgment cycle Hn is expressed by the slope of the cumulative pressure loss ΔSn / Hn, and the slope of the cumulative pressure loss in the previous judgment, i.e., the (n-1)th judgment cycle Hn-1, is similarly expressed as (ΔSn-1 / Hn-1). Let... Figure 11 The judgment period Hn-2 (=(tn-2)-(tn-3)) has the same length as the judgment period Hn-1 (=(tn-1)-(tn-2)), and the pressure loss δp during this period is a constant value. Therefore Figure 12 The curve of cumulative pressure loss S in the judgment period Hn-2 and judgment period Hn-1 has the same slope (ΔSn-2 / Hn-2) and (ΔSn-1 / Hn-1). On the other hand, Figure 11 During the judgment period Hn-1 (=(tn-1)-(tn-2)) and the judgment period Hn (=(tn)-(tn-1)), the pressure loss δp increases. At this time, the increase in cumulative pressure loss ΔSn is greater than ΔSn-1 and ΔSn-2. Therefore, the slope ΔSn / Hn is greater than (ΔSn-2 / Hn-2) and (ΔSn-1 / Hn-1) mentioned above.

[0099] Figure 13 Is for Figure 10 The cumulative pressure loss curves 950 (without pre-filter) and 960 (with pre-filter) are used to generate and compare the slopes ΔS / H980 and ΔS' / H990 of the cumulative pressure loss curves 950 and 960, respectively. It can be seen that the slope ΔS / H980 of the cumulative pressure loss curve without a pre-filter increases rapidly during the operating time, particularly during the period when the blockage of the intake filter 601 rapidly develops from the middle of the operation. On the other hand, the slope ΔS' / H990 of the cumulative pressure loss curve with a pre-filter also changes due to the occurrence of pre-filter blockage and the removal of blockage through cleaning, and a peak can be identified. By calculating the slope of the cumulative pressure loss in this way, the determination of the pre-filter blockage state becomes easier.

[0100] Furthermore, as Figure 9 shown, by combining with the average load factor R of the compressor, for example, when the load factor is large, it is possible to distinguish between an increase in the cumulative pressure loss caused by a large amount of air passing through the filter and an increase in the cumulative pressure loss caused by the development of clogging of the pre-filter. Thus, it is possible to change the determination cycle H for cleaning the pre-filter according to the degree of clogging of the filter.

[0101] For example, Figure 9 in, in step S113, when (ΔSn-1 / Hn-1) < (ΔSn / Hn) holds, it proceeds to step S114. This indicates that the pressure loss has increased compared to the previous determination. In step S114, when R ≤ RM does not hold, it is determined as a high load factor and proceeds to step S117. Since it is presumed to be a state of high load factor and large pressure loss, the determination cycle H maintains the current determination cycle. On the other hand, when R ≤ RM holds in step S114, it proceeds to step S116. Here, if R ≤ RL holds, it is determined as a low load factor and proceeds to step S122. At this time, although it is a low load factor but the pressure loss is large, it is therefore determined that the clogging of the pre-filter has developed to a considerable extent, and it is updated to a shorter determination cycle Hn × α2 obtained by multiplying the current determination cycle Hn by the reduction factor α2. On the other hand, when R ≤ RL does not hold in step S116, that is, it is determined as a medium load factor in the range of RL < R ≤ RM, and in the next step S123, it is updated to a shorter determination cycle Hn × α1 obtained by multiplying the current determination cycle Hn by the reduction factor α1. Here, the reduction factors have the relationship of α2 < α1 < 1. As a result, in a state where the load factor is smaller and the pressure loss is larger, the determination cycle H is shortened more.

[0102] On the other hand, when (ΔSn-1 / Hn) < (ΔSn / Hn) does not hold in step S113, proceed to step S115. In step S115, further determine whether (ΔSn / Hn) < (ΔSn-1 / Hn-1) holds. If it holds, proceed to step S118. If it does not hold, that is, (ΔSn / Hn) = (ΔSn-1 / Hn-1), which indicates that there is no change in pressure loss during the previous and current judgment cycles, proceed to step S119. In step S118 above, if R ≤ RM holds, proceed to the next step S120. If R ≤ RL holds in step S120, it is determined as a low load rate, and proceed to step S124. At this time, it is determined as a low load rate and the pressure loss is small, and the judgment cycle Hn maintains the current judgment cycle. On the other hand, when R ≤ RM does not hold in step S118, it is determined as a high load rate, and proceed to step S121. Since it is speculated that the situation is a high load rate and the pressure loss is small, it can be determined that the progress of the clogging of the pre-filter is slow. Therefore, it is updated to a longer judgment cycle Hn × β2 obtained by multiplying the current judgment cycle Hn by the increase coefficient β2. When R ≤ RL does not hold in step S120, that is, it is determined as a medium load rate within the range of RL < R ≤ RM. In the next step S125, it is updated to a longer judgment cycle Hn × β1 obtained by multiplying the current judgment cycle Hn by the increase coefficient β1. Here, there is a relationship of 1 < β1 < β2 for the increase coefficient. As a result, in the state where the pressure loss is small, the larger the load rate, the longer the judgment cycle Hn is extended.

[0103] When the above step S115 does not hold, proceed to step S119. In step S119, the slope of the initial cumulative pressure loss ΔS1 / H1 obtained from the increase amount ΔS1 of the cumulative pressure loss during the judgment period H1 between the first pre-filter judgment and the second pre-filter judgment after the compressor starts running is compared with the slope of the cumulative pressure loss ΔSn / Hn at the current judgment. When (ΔS1 / H1) < (ΔSn / Hn) holds, proceed to step S126, substitute the current judgment period Hn for Hn, and maintain the length of the judgment period. When it does not hold, converge to the load rate judgment process of step S118. As the effect of step S119, even if the slopes of the pressure losses in the previous and current judgment periods are the same and unchanged, when the clogging of the pre-filter progresses and the absolute value of the slope is large, it is preferable not to extend the judgment period Hn. Therefore, the slope of the initial cumulative pressure loss ΔS1 / H1, which is one of the evaluation benchmarks for the slope of the cumulative pressure loss, is compared with the slope of the cumulative pressure loss ΔSn / Hn at the current judgment. When (ΔS1 / H1) < (ΔSn / Hn) holds, the length of the judgment period is maintained. Regarding the slope of the initial cumulative pressure loss ΔS1 / H1, since it is assumed that the clogging degree of the suction filter 601 is small and it is predicted that the influence of the slope of the cumulative pressure loss caused by the clogging of the pre-filter is likely to occur, by using the slope of the cumulative pressure loss ΔS1 / H1 at this time as the evaluation benchmark, the appropriateness of the slope of the cumulative pressure loss ΔSn / Hn at the current judgment is improved.

[0104] The judgment period Hn changes according to the magnitude of the slope of the cumulative pressure loss and the magnitude of the average load rate. For the judgment period updated in steps S121, S122, S123, and S125, in order not to continuously become shorter due to the reduction coefficient α or continuously become longer due to the increase coefficient β due to conditions, the upper limit judgment period HHH and the lower limit judgment period HLL are predefined, so that the judgment period H does not change to exceed the above upper and lower limits. After the above steps S122 and S123, proceed to step S127. When Hn ≤ HLL holds, substitute HLL for the judgment period Hn and proceed to step S110. Similarly, after the above steps S121 and S125, proceed to step S129. When HHH ≤ Hn holds, substitute HHH for the judgment period Hn and proceed to step S110. After the above steps S117, S124, and S126, the judgment period Hn is maintained in the state at the previous judgment, so proceed to the above step S110.

[0105] As described above, according to this embodiment, the determination of the clogging status of the pre-filter becomes easier based on the combination of the slope ΔS of the cumulative pressure loss curve and the average load rate R. Similar to Embodiment 1, the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air can be optimized in accordance with the type and load rate of the gas compressor.

[0106] Example 8

[0107] In this embodiment, an example is described for Embodiment 7, which, as in Embodiment 2, indicates the cleaning or replacement of the pre-filter taking into account changes in the input current of the cooling fan.

[0108] Figure 14 This is a flowchart illustrating the process for determining when to clean or replace the pre-filter in this embodiment. Figure 14 In, with Figure 9 The same processing steps are appended with the same symbols, and their descriptions are omitted. Figure 14 In, with Figure 9 The difference is that step S201 has been added.

[0109] Figure 14 In, such as Figure 3 As explained in the text, in step S201, a predetermined threshold Ith is preset for the input current If of the cooling fan 204. If the input current If of the cooling fan is less than the predetermined threshold Ith, it is determined that the blockage of the cooling fan pre-filter has developed to a certain extent, and the process proceeds to step S102 to display an alarm.

[0110] As described above, according to this embodiment, in addition to the effects of Embodiment 7, it also has the effect of being able to determine the blockage of the pre-filter for cooling air in advance.

[0111] Example 9

[0112] In this embodiment, an example is described where, in Example 8, the cooling fan is driven by an inverter and its speed is controlled by a variable speed, and the blockage of the pre-filter 600b for the cooling air is detected in advance.

[0113] Figure 15 This is a flowchart illustrating the process for determining when to clean or replace the pre-filter in this embodiment. Figure 15 In, with Figure 14 The same processing steps are appended with the same symbols, and their descriptions are omitted. Figure 15 In, with Figure 14 The difference is that step S201 is replaced with step S301.

[0114] Figure 15 In, such as Figure 6As explained, if the predicted value Io of the inverter input current at the specified output frequency and the measured value Iif of the inverter input current for the cooling fan are, for example, only 60% or less, it is determined that the cooling fan pre-filter is blocked, and the process proceeds to step S102 to display an alarm.

[0115] As described above, according to this embodiment, similar to Embodiment 8, it has the effect of being able to determine the blockage of the pre-filter for cooling air in advance.

[0116] The embodiments described above are examples, but the present invention is not limited to the above embodiments and includes various modifications. For example, the gas compressor described in the above embodiments is an oil-free two-stage screw air compressor, but it is not limited to this type of fluid machinery. For example, it can also be a single-stage compressor with only one compressor body, or it can be applied to an oil-supply compressor that injects lubricating oil into the compression chamber inside the compressor body for the purpose of cooling and sealing compressed air and lubricating the sliding surfaces of the male and female screw rotors (not shown).

[0117] Furthermore, the gas compressors of Embodiments 1 to 9 described above are air-cooled, but even water-cooled compressors, in the case of having an air intake 2a for compressed air, a small cooling fan for air exchange in the housing, and a self-cooling fan on the side of the motor 103 opposite to the load, most are provided with an air intake 3a for cooling air, regardless of size. Therefore, the above embodiments can also be applied to water-cooled compressors.

[0118] In addition, the compression method is not limited to the twin-screw type with a male and female screw rotor in the above embodiment. It can also be applied to various positive displacement compressors such as single-screw, gear, and reciprocating compressors, which consist of a screw rotor and multiple gate rotors, as well as centrifugal and axial flow turbo compressors.

[0119] Furthermore, the above embodiments are described in detail for ease of understanding of the present invention and are not limited to having all the structures described. Additionally, a portion of the structure of one embodiment can be replaced with the structure of another embodiment, and structures of other embodiments can be added to the structure of one embodiment. Furthermore, for a portion of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0120] Explanation of reference numerals in the attached figures

[0121] 1: Gas compressor; 2a: Inlet; 2b: Inlet duct; 3a: Inlet for cooling air; 3b: Cooling air duct; 101: Low-pressure stage compressor body; 102: High-pressure stage compressor body; 103: Electric motor; 201: Intercooler; 202: Aftercooler; 204: Cooling fan; 600a: Pre-filter for compressed air; 600b: Pre-filter for cooling air; 601: Inlet filter; 701: Display and input device; 702: Storage device; 703: Control device; 703a: Inverter for cooling fan; 703b: Inverter for electric motor; 900, 910: Pressure loss curves Lines 950, 960, 970: Cumulative pressure loss curves; 980, 990: Slope of the cumulative pressure loss curves; Ps: Suction pressure; Ps0: Suction pressure alarm setpoint; R: Average load rate of the gas compressor; Rc: Current load rate of the gas compressor; Rf: Average load rate of the cooling fan; Rfc: Current load rate of the cooling fan; RH: High load rate judgment value; RM: Medium load rate judgment value; RL: Low load rate judgment value; HH: High-frequency cleaning cycle; HM: Normal cleaning cycle; HL: Low-frequency cleaning cycle; Hc: Cumulative running time from the final cleaning instruction to the present; H: Judgment cycle.

Claims

1. A gas compressor comprising: a pre-filter for primary dust removal at a compressed air intake port of a housing; an intake filter for secondary dust removal; at least one compressor body for compressing air drawn in via the intake filter and an intake passage; an electric motor for driving the compressor body; an air cooler for cooling the compressed air; a cooling fan for passing cooling air through the air cooler; a cooling air intake port for drawing in gas from external gas using the cooling fan; a cooling air pre-filter provided at the cooling air intake port; and a control device for controlling the operation of the compressor. The gas compressor is characterized in that: The control device determines the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air based on the load rate, which is an indicator of the operating status. The compressor body is a constant speed compressor. Let T3 be the cycle time for the compressor body to operate under load and without load once, T1 be the time for no-load operation, T2 be the time for load operation, N be the number of cycles, T3 = T1 + T2, the current load rate Rc = T2 ÷ T3, and the average load rate R = ∑Rc / N. The control device calculates the average load rate R as the load rate, and determines the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air by comparing the average load rate R with the load rate judgment value.

2. The gas compressor as described in claim 1, characterized in that: The cooling fan is speed-controlled. The control device calculates the average load rate Rf of the cooling fan, compares the average load rate R of the compressor body with the average load rate Rf of the cooling fan, and uses the value of the larger load rate to determine the frequency of cleaning or replacement of the pre-filter for compressed air and the pre-filter for cooling air.

3. The gas compressor as described in claim 1, characterized in that: The cooling fan is speed-controlled. It includes an ammeter for measuring the input current of the cooling fan and a display device. When the input current of the cooling fan is less than a predetermined threshold, the control device displays an instruction on the display device to clean or replace the pre-filter for cooling air, or the pre-filter for compressed air and the pre-filter for cooling air.

4. The gas compressor as described in claim 1, characterized in that: The cooling fan is variable speed controlled. It has a speed control device for controlling the speed of the cooling fan. Let T3 be the cycle time for the cooling fan to operate under load and without load once, T1 be the time for no-load operation, T2 be the time for load operation, T3 = T1 + T2, the current frequency of the speed control device be ffc, the rated frequency of the speed control device be frr, the number of operation cycles be N, and the current load rate of the cooling fan be Rfc = (T2·ffc) ÷ (T3·ffr). The control device calculates Rf = ∑Rfc / N as the average load rate Rf of the cooling fan. The cleaning or replacement frequency of the pre-filter for compressed air and the pre-filter for cooling air is determined by comparing the average load rate R of the compressor body with the average load rate Rf of the cooling fan, and comparing the value of the larger load rate with the load rate judgment value.

5. A gas compressor comprising: a pre-filter for primary dust removal at a compressed air intake port of a housing; an intake filter for secondary dust removal; at least one compressor body for compressing air drawn in via the intake filter and an intake passage; an electric motor for driving the compressor body; an air cooler for cooling the compressed air; a cooling fan for passing cooling air through the air cooler; a cooling air intake port for drawing in gas from external gas using the cooling fan; a cooling air pre-filter provided at the cooling air intake port; and a control device for controlling the operation of the compressor. The gas compressor is characterized in that: The control device determines the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air based on the load rate, which is an indicator of the operating status. The compressor body is a variable speed motor. It has a speed control device for speed control of the compressor body. Let T3 be the cycle time for the compressor body to operate under load and without load once, T1 be the time for no-load operation, T2 be the time for load operation, T3 = T1 + T2, the current frequency of the speed control device be fc [Hz], the rated frequency of the speed control device be fr [Hz], the number of operation cycles be N, the current load rate Rc = (T2·fc) ÷ (T3·fr), and the average load rate R = ∑Rc / N. The control device calculates the average load rate R as the load rate, and determines the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air by comparing the average load rate R with the load rate judgment value.

6. The gas compressor as described in any one of claims 1, 4, and 5, characterized in that: The cooling air intake and the cooling air pre-filter replace the compressed air intake and the compressed air pre-filter, and thus also have their functions.

7. A gas compressor comprising: a pre-filter for primary dust removal at a compressed air intake port of a housing; an intake filter for secondary dust removal; at least one compressor body for compressing air drawn in via the intake filter and an intake passage; an electric motor for driving the compressor body; an air cooler for cooling the compressed air; a cooling fan for passing cooling air through the air cooler; a cooling air intake port for drawing in gas from external gas using the cooling fan; a cooling air pre-filter provided at the cooling air intake port; and a control device for controlling the operation of the compressor. The gas compressor is characterized in that: The control device determines the frequency of cleaning or replacing the pre-filter for compressed air and the pre-filter for cooling air based on the load rate, which is an indicator of the operating status. Equipped with an inhalation pressure sensor, The compressor body is a constant speed compressor. Let T3 be the cycle time for the compressor body to operate under load and without load once, T1 be the time for no-load operation, T2 be the time for load operation, N be the number of cycles, T3 = T1 + T2, the current load rate Rc = T2 ÷ T3, and the average load rate R = ∑Rc / N. The control device calculates the cumulative value of the suction pressure detected by the suction pressure sensor corresponding to the operating time, i.e., the cumulative pressure loss, and determines the cleaning or replacement frequency of the pre-filter for compressed air and the pre-filter for cooling air based on the change in the cumulative pressure loss over a specified period of time and the average load rate R.

8. The gas compressor as described in claim 7, characterized in that: The cooling fan is speed-controlled. It includes an ammeter for measuring the input current of the cooling fan and a display device. When the input current of the cooling fan is less than a predetermined threshold, the control device displays an instruction on the display device to clean or replace the pre-filter for cooling air, or the pre-filter for compressed air and the pre-filter for cooling air.

Images