air compressor

Abstract

To provide a package type and air cooling type air compressor which can recommend cooler cleaning at proper timing, while suppressing cost increase.SOLUTION: A package type and air cooling type air compressor includes, in a package; two cooling paths to an air cooling type cooler and a motor; two cooling air suction ports for the cooling paths to take in the outside air; a fan and an exhaust port for exhausting the cooling air after cooling of the cooler and the motor collectively to the outside; and two temperature sensors for detecting the temperature of bearings arranged on both shaft ends of the motor. The air compressor also includes: a control part which calculates a temperature difference in the bearings arranged on the upstream side (anti-load side) and the upstream side (load side) of the flow direction of the cooling air on both ends of the motor shaft, and which determines clogging of the cooler in the case where the temperature difference is below a threshold value; and a display part for notifying of recommendation of cleaning in the case where the cooler is determined to be clogged.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a packaged, air-cooled air compressor. [Background technology]

[0002] In packaged, air-cooled air compressors, the filter for sucking in compressed air (suction filter) and the air-cooled heat exchanger (cooler) for cooling the compressed air and lubricating oil are notified via the instruction manual or touch panel, etc., to prevent performance degradation due to clogging caused by dust and other particles contained in the outside air, and to indicate when cleaning should be performed at specified operating times or intervals.

[0003] The progression of clogged filters and coolers varies depending on the operating environment, etc. If cleaning is not done properly, the compressor may stop operating due to a rise in the temperature of the compressed air, or the compressor may lose function, resulting in increased power consumption and a shortened component life. If the filter is heavily soiled, the amount of cleaning work required may increase. On the other hand, if cleaning is done too early, this may result in extra work, leading to reduced operating efficiency of the air compressor and increased costs.

[0004] The technology shown in Patent Document 1 discloses a method for estimating the progression of clogging and determining whether the filter is clogged by using an existing sensor that detects the pressure (discharge pressure) and temperature (discharge temperature) of the compressed air installed in the compressor in an outside air filter installed for sucking in compressed air, and setting threshold values ​​for the detected temperature and pressure. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-14790 Summary of the Invention [Problem to be solved by the invention]

[0006] When a cooler becomes clogged, the compressed air is not cooled sufficiently, so according to the technology of Patent Document 1, it is possible to estimate cooler clogging based on the discharge temperature detected by a sensor. However, if the discharge temperature changes due to other factors such as a clogged intake filter, or if multiple coolers are used, such as for oil, the accuracy of estimating cooler clogging may be reduced. Also, while cooler clogging can be estimated by adding sensors that detect the flow rate of cooling air flowing through the cooler and the differential pressure in the cooling air path, there is a problem of increased costs due to the addition of sensors, changes to the control for detecting flow rate and pressure, and the addition of equipment. [Means for solving the problem]

[0007] Solutions to the above problems are shown below.

[0008] This is a packaged, air-cooled air compressor that includes a compressor body, a motor that drives the compressor body, a cooler that cools the air compressed by the compressor body, the motor, and the compressor body, and a housing that houses the compressor body, the motor, and the cooler.

[0009] The air compressor has a cooler cooling path that takes in external air through a cooler intake port provided in the housing and cools the cooler, and a motor cooling path that takes in external air through a motor intake port provided in the housing and cools the motor, and separates these paths.The cooler duct has an opening that merges the cooler cooling path and the motor cooling path, and an exhaust port provided in the housing that expels the air from the cooler cooling path and the motor cooling path that have merged through the opening outside the housing.

[0010] The air compressor further includes a first sensor that detects the temperature of the load side bearing of the motor and a second sensor that detects the temperature of the non-load side bearing, a control unit that calculates the temperature difference between the first sensor and the second sensor and determines that the cooler is clogged if the temperature difference is less than a threshold value, and a display unit that notifies the user that cleaning is recommended if it is determined that the cooler is clogged.

[0011] These methods utilize the fact that when the cooler becomes clogged, the amount of cooling air passing through the cooler cooling path decreases, and the amount of cooling air passing through the motor cooling path increases, thereby reducing the temperature difference between the two bearings at both ends of the motor shaft.Since existing sensors can be used to estimate cooler clogging, it is possible to suppress cost increases and to notify the recommendation to clean the cooler at the appropriate time. [Effects of the Invention]

[0012] According to the present invention, by using an existing sensor installed in the air compressor to estimate the clogging of the cooler, it is possible to suppress an increase in costs and recommend the cooler cleaning at an appropriate time. Other issues, configurations, and effects will be described in the following description of the embodiment. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of an air-cooled oil-free screw compressor. [Figure 2] FIG. 2 is a diagram illustrating a cooling system structure and a cooling air path. [Figure 3] FIG. 10 is a diagram showing the relationship between the amount of cooling air and the temperature difference between the motor bearings. [Figure 4] FIG. 4 is a flowchart of the control device. DETAILED DESCRIPTION OF THE INVENTION

[0014] Specific embodiments of the present invention will be described below with reference to the drawings.

[0015] FIG. 1 is a schematic diagram of an air-cooled oil-free screw compressor according to this embodiment. The air compressor 100 has a multi-stage compressor body, which includes a low-pressure stage compressor body 2 and a high-pressure stage compressor body 3. Each compressor body includes a casing 5 that houses a pair of male and female screw rotors that mesh with each other, and a speed-increasing gear 6 that rotates and drives the low-pressure stage compressor body 2 and the high-pressure stage compressor body 3. The air compressor 100 is not limited to one having a two-stage compressor body.

[0016] The air compressor 100 further includes a motor (electric motor) 4 that drives each compressor, a compressed air intake port 50 that takes in external air used for compression, a cooler intake port 51 that takes in external air used to cool the cooler, a motor intake port 52 that takes in external air used to cool the motor, a low-pressure stage discharge air cooler 10, a high-pressure stage discharge air cooler 11, an oil cooler 12, a control unit 30 that controls the motor 4, a display unit 31, and a housing 60 that houses them. The low-pressure stage discharge air cooler 10, the high-pressure stage discharge air cooler 11, and the oil cooler 12 are collectively referred to simply as coolers.

[0017] The compressor body of the air compressor 100 has a plurality of compression chambers formed in the tooth grooves of the screw rotor. The low-pressure stage compressor body 2 and the high-pressure stage compressor body 3 are each driven by a motor 4 serving as a drive source, and are rotated via a speed-increasing gear 6. The control unit 30 is composed of, for example, a CPU and memory, and controls the motor 4 as well as the display of the display unit 31. The control unit 30 can also be composed of an FPGA or ASIC instead of a CPU.

[0018] External air used for compression is taken in through a compressed air intake port 50 provided in the housing 60, supplied to the low-pressure stage compressor main body 2 via a compressed air intake duct 42 and an intake filter 1, and compressed to a predetermined pressure. The compressed and heated air is cooled in a low-pressure stage discharge air cooler 10 and then supplied to the high-pressure stage compressor main body 3. The high-pressure stage compressor main body 3 compresses the heated air to a predetermined pressure and cools it in a high-pressure stage discharge air cooler 11 before discharging it to the outside of the compressor 14. The low-pressure stage discharge air cooler 10 and the high-pressure stage discharge air cooler 11 are called air-cooled coolers. The path along which external air used for compression is taken in, passes from the low-pressure stage compressor main body 2 via the low-pressure stage discharge air cooler 10, passes from the high-pressure stage compressor main body 3 via the high-pressure stage discharge air cooler 11, and is discharged to the outside is called the compression system.

[0019] The oil used for lubrication and cooling is supplied to a reservoir 17 in the gear casing 5, and after being cooled in an oil cooler 12 via an oil pump 7, it branches into a lubrication path 15 and a cooling path 16 and is supplied to each device.

[0020] In the lubrication path 15, oil is supplied to the speed-increasing gear 6, the bearings provided in the low-pressure stage compressor body 2, and the high-pressure stage compressor body 3, and then recovered in a reservoir 17 inside the gear casing 5. In the cooling path 16, oil is supplied to the jacket parts of the casings provided in each compressor body, in the order of the high-pressure stage compressor body 3 and the low-pressure stage compressor body 2, and then recovered in the reservoir 17 inside the gear casing 5.

[0021] The cooling air from the low-pressure stage discharge air cooler 10, the high-pressure stage discharge air cooler 11, and the oil cooler 12 is taken into the air compressor 100 through a cooler intake port 51 provided in the housing 60. The cooling air for cooling the motor is taken into the air compressor 100 through a motor intake port 52 provided in the housing 60.

[0022] In the cooler cooling path, external air for the cooler cooling is taken in from the cooler intake port 51 by the cooling fan 13, and is supplied to the low-pressure stage discharge air cooler 10, the high-pressure stage discharge air cooler 11, and the oil cooler 12 via the cooler duct 41, thereby cooling each of them.

[0023] In the motor cooling path, external air for cooling the motor is taken in from the motor intake port 52 by a self-cooling fan provided on the cooling air intake side of the motor. The taken-in external air passes through the motor cooling air intake duct (motor duct 40) and is then supplied to the anti-load side bearing 61 provided on the motor 4, the housing, and the load side bearing 62 in that order. The bearing is then supplied to the housing bracket, The air after cooling the motor is collected together with air that has become hot due to heat-generating elements other than the cooler unit provided inside the air compressor 100, such as the compressor bodies 2 and 3, their piping, and electrical components, and is drawn into the cooler duct 41 through an opening 54 at the top of the cooler duct 41, and is then released outside the air compressor together with the air that has cooled the cooler through a cooling air exhaust port 53 provided on the exhaust side of the cooling fan 13.

[0024] The cooler cooling path and the motor cooling path are configured so that cooling air is taken in from the outside through different intake ports (cooler intake port 51 for cooler cooling air, motor intake port 52 for motor cooling air) provided in the housing 60 of the air compressor 100 and discharged to the outside from a single cooling air exhaust port 53 of the air compressor 100 by a common fan 13. The cooler duct 41 supplies outside air via the cooler intake port 51 to the low-pressure stage discharge air cooler 10, the high-pressure stage discharge air cooler 11, and the oil cooler 12, and also has the function of separating it from the motor cooling path within the housing 60 of the air compressor 100.

[0025] To protect the motor 4 provided in the air compressor 100 from fire or damage due to temperature rise, a motor load-side bearing temperature sensor 20 is provided on the bracket that houses the load-side bearing 62, and a motor anti-load-side bearing temperature sensor 21 is provided on the bracket that houses the anti-load-side bearing 61. The control unit 30 records the temperatures detected by each sensor, and if a preset temperature is exceeded, the compressor is stopped and the display unit 31 displays the reason for the compressor stopping, such as "abnormal motor temperature."

[0026] 2 shows an outline of the arrangement of the low-pressure stage discharge air cooler 10, the high-pressure stage discharge air cooler 11, and the oil cooler 12 (various coolers) and the flow of cooling air in the cooler cooling path and motor cooling path of this embodiment. The high-pressure stage discharge air cooler 11 is provided across the entire depth direction of the page, the low-pressure stage discharge air cooler 10 is provided in the front part of the page below the high-pressure stage discharge air cooler 11, and the oil cooler 12 is provided in the rear part of the page below the high-pressure stage discharge air cooler 11.

[0027] 2, the cooling path of air compressor 100 is divided into an upper cooler cooling path and a lower motor cooling path. The cooler cooling path and motor cooling path have two separate intake ports, cooler intake port 51 and motor intake port 52, which each take in external air for cooling. However, the two paths (cooler cooling path and motor cooling path) join at opening 54 at the top of cooler duct 41, and cooling air is discharged from a single shared cooling air exhaust port 53 by fan 13.

[0028] Therefore, if the airflow through the various coolers decreases due to clogging of the coolers, the airflow for cooling the motor increases. In other words, the flow rate in the cooler cooling path decreases, while the flow rate in the motor cooling path increases. In the motor cooling path, the cooling air for the motor cools the load side bearing 62 and the non-load side bearing 61, but because the structure makes it easier to cool the non-load side bearing 61, the load side bearing 62 tends to become hotter. Therefore, if the cooling airflow increases, the load side bearing 62 will achieve the same cooling effect as the non-load side bearing 61, and the temperature difference between the two bearings will become smaller. These characteristics are used to determine whether the coolers are clogged.

[0029] FIG. 3 is a graph showing the relationship between the motor cooling airflow rate and the bearing temperature difference. The bearing temperature difference Tfb is calculated by the control unit 30 by subtracting the temperature Tb detected by the non-load-side bearing temperature sensor 21 from the temperature Tf detected by the load-side bearing temperature sensor 20. During normal operation when the various coolers are not clogged, the bearing temperature difference Tfb is large. However, if the various coolers become clogged and the motor cooling airflow rate increases, the bearing temperature difference Tfb decreases. That is, if the cooler becomes clogged and the bearing temperature difference Tfb falls below a threshold, the control unit 30 determines that the cooler is clogged and displays a message such as "Cleaning the Cooler" on the display unit 31 to recommend cleaning the cooler. The cooler clog determined by the control unit 30 refers to a state in which one, two, or all of the low-pressure stage discharge air cooler 10, high-pressure stage discharge air cooler 11, and oil cooler 12 are clogged.

[0030] Here, an advantage of determining cooler clogging using the bearing temperature difference is that although the bearing temperature changes depending on the motor rotation speed and current, the load condition of the compressor body, and the temperature of the external air, the influence of these factors can be eliminated by using the temperature difference between the anti-load side bearing 61 and the load side bearing 62. Furthermore, this temperature difference is not limited to the bearings, and a temperature sensor used in another heat-generating part (for example, a coil) can also be used.

[0031] In this embodiment, the determination of cooler clogging is applied only when the air compressor 100 is operating under load. This is because, during unloaded operation, the load on the compressor bodies 2 and 3 is low, resulting in a lower bearing temperature between the non-load-side bearing 61 and the load-side bearing 62, and a smaller temperature difference between them. However, during unloaded operation, the temperatures of the compressed air and oil cooled in the cooler cooling path are low. Therefore, even if the cooler is clogged, no particular problem will arise even if cleaning is not performed. Therefore, it is considered that determination of clogging is unnecessary. Here, "loaded operation" refers to a state in which the compressor is operating under load while discharging compressed air. On the other hand, "unloaded operation" refers to a state in which the compressor is operating under low load while discharging a small amount of intake air so as not to stop the compressor.

[0032] 4 is a flowchart of the control device. When the control unit 30 starts control in step S40, the control unit 30 first determines in step S41 whether the operating state of the air compressor 100 is load operation or unload operation, and if it is load operation, the process proceeds to step S42.

[0033] In step S42, the temperature Tf detected by the load side bearing temperature sensor 20 and the temperature Tb detected by the anti-load side bearing temperature sensor 21 are detected. Note that the order of steps S41 and S42 can be reversed without causing any problems, and temperature detection by the load side bearing temperature sensor 20 and the anti-load side bearing temperature sensor 21 may be performed in an operating state other than load operation.

[0034] In step S43, the control unit 30 calculates the bearing temperature difference Tfb=Tf-Tb based on the temperature detected in step S42.

[0035] In step S44, the control unit 30 determines whether the bearing temperature difference Tfb is smaller than a predetermined threshold. If the bearing temperature difference Tfb is smaller than the predetermined threshold, the process proceeds to step S45; if not, the process returns to step S42 and performs temperature detection. In this step, it may be determined whether the bearing temperature difference Tfb is equal to or smaller than the predetermined threshold. In either case, the predetermined threshold is stored in advance in a memory (not shown) of the control unit 30.

[0036] In step S45, the control unit 30 outputs a warning signal to the display unit 31 informing the display unit 31 that the cooler is clogged.

[0037] In step S46, the display unit 31 displays "Clean Cooler" to recommend cleaning the cooler based on the warning signal output from the control unit 30. This display may take other forms as long as it is capable of recommending cleaning the cooler to the user.

[0038] As described above, according to this embodiment, by using the existing sensors provided in the air compressor 100, the anti-load side bearing temperature sensor 21 and the load side bearing temperature sensor 20, clogging of the cooler can be estimated, thereby suppressing cost increases and recommending cooler cleaning at an appropriate time.

[0039] Although the present embodiment has been described with reference to an air-cooled oil-free screw compressor, the determination of cooler clogging according to the present invention can also be applied to oil-cooled air compressors and single-stage or multi-stage air compressors. [Explanation of symbols]

[0040] 1: Intake filter, 2: Low-pressure stage compressor body, 3: High pressure stage compressor body, 4: Motor, 5: Gear casing, 6: Speed ​​increasing gear, 7: Oil pump, 10: Low pressure stage discharge air cooler, 11: High pressure stage discharge air cooler, 12: Oil cooler, 13: Cooling fan, 15: Lubrication path, 16: Cooling path, 17: Reservoir, 20: Temperature sensor for motor load side bearing, 21: Temperature sensor for motor non-load side bearing, 30: control unit, 31: Display section, 40: Motor cooling air intake duct, 41: Cooler duct, 42: Compressed air intake duct, 50: compressed air intake, 51: Cooler intake for cooler cooling air, 52: Motor cooling air intake for motor, 53: Cooling air exhaust port, 54: Opening at the top of the cooler duct, 60: Housing, 100: Air compressor.

Claims

1. An air compressor comprising: a compressor body; a motor that drives the compressor body; a cooler that cools air compressed by the compressor body, the motor, and the compressor body; and a housing that houses the compressor body, the motor, and the cooler, a cooler duct that separates a cooler cooling path that takes in external air through a cooler intake port provided in the housing to cool the cooler and a motor cooling path that takes in external air through a motor intake port provided in the housing to cool the motor, and has an opening that merges the cooler cooling path and the motor cooling path; an exhaust port provided in the housing for discharging air from the cooler cooling path and the motor cooling path, which are joined by the opening, to the outside of the housing; a first sensor for detecting the temperature of a load side bearing of the motor and a second sensor for detecting the temperature of a non-load side bearing; a control unit that calculates a temperature difference between the first sensor and the second sensor, and determines that the cooler is clogged when the temperature difference is less than a threshold value; Air compressor.

2. 2. The air compressor according to claim 1, It has a display unit, When the control unit determines that the cooler is clogged, the control unit outputs a warning signal to the display unit, The display unit displays a message recommending cleaning of the cooler based on a warning signal from the control unit. Air compressor.

3. 3. The air compressor according to claim 2, The control unit It is determined whether the air compressor is in a load operation, and when the air compressor is in a load operation, the temperature difference between the first sensor and the second sensor is calculated, and if the temperature difference is less than a threshold value, it is determined that the cooler is clogged. Air compressor.

4. 4. The air compressor according to claim 3, The compressor body has a multi-stage configuration including a low-pressure stage compressor body and a high-pressure stage compressor body. Air compressor.

5. 4. The air compressor according to claim 3, The cooler is an air cooler that cools the air compressed by the compressor body; an oil cooler that cools the motor and the compressor body; Air compressor.

6. 6. The air compressor according to claim 5, the compressor body has a multi-stage configuration including a low-pressure stage compressor body and a high-pressure stage compressor body, The air cooler includes a low-pressure stage discharge air cooler that cools compressed air from the low-pressure stage compressor body, and a high-pressure stage discharge air cooler that cools compressed air from the high-pressure stage compressor body. Air compressor.

7. A compressor body, a motor that drives the compressor body; an air cooler that cools the air compressed by the compressor body; an oil cooler that cools the motor and the compressor body; An air compressor having the compressor body, the motor, and a housing that houses the air cooler and the oil cooler, The housing includes: a cooler intake port for taking in external air used to cool the air cooler and the oil cooler; a motor intake port for taking in external air used to cool the motor, The air compressor is a cooler duct separating a cooler cooling path that cools the air cooler and the oil cooler with air taken in through the cooler intake port from a motor cooling path that cools the motor with air taken in through the motor intake port within the housing; the cooler duct has an opening at which the cooler cooling path and the motor cooling path join together, The air compressor is a cooling air exhaust port for discharging the air of the cooler cooling path and the motor cooling path joined by the opening to the outside of the air compressor; a first sensor for detecting the temperature of a load side bearing of the motor and a second sensor for detecting the temperature of a non-load side bearing; a control unit that calculates a temperature difference between the first sensor and the second sensor, and determines that the air cooler or the oil cooler is clogged when the temperature difference is less than a threshold value, and outputs a warning signal; a display unit that displays a message recommending cleaning of the cooler based on a warning signal from the control unit. Air compressor.

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