Air compressor

Abstract

The invention provides a packaged air-cooled air compressor which can recommend cleaning of a cooler at an appropriate timing while suppressing an increase in cost. A packaged air-cooled air compressor has, in a package: two cooling paths leading to an air-cooled cooler and an electric motor; the cooling path is provided with two suction ports for sucking two cooling air of outside air; the fan and the spraying port are used for gathering cooling air cooled by the cooler and the motor and discharging the cooling air to the outside; the present invention is provided with two temperature sensors for detecting the temperature of bearings disposed at both ends of a shaft of a motor, and is provided with: a control unit for calculating the temperature difference between the bearings disposed at the upstream side (opposite load side) and the downstream side (load side) in the flow direction of cooling air disposed at both ends of the shaft of the motor, and determining that a cooler is clogged when the temperature difference is less than a threshold value; and a display unit that reports a recommendation for cleaning when it is determined that the cooler is clogged.

Description

Technical Field

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

[0002] In a sealed and air-cooled air compressor, it is necessary to prevent the filter for compressed air intake (intake filter) and the air-cooled heat exchanger (cooler) for cooling compressed air and lubricating oil from being clogged and reduced in capacity due to dust contained in the outside air. Therefore, the predetermined operating time or cleaning work for each period is notified through the instruction manual or the touch panel.

[0003] The progress of filter and cooler clogging varies depending on the use environment, etc., and adverse conditions may occur during regular cleaning. For example, if the cleaning timing is late, the compressor stops running due to the increase in the temperature of the compressed air, the power consumption increases due to the reduced function of the compressor body, and the life of the components decreases. In the case of severe dirt, it is believed that the cleaning operation time increases. On the other hand, if the cleaning timing is early, it becomes redundant work, which is believed to lead to reduced operating efficiency of the air compressor and increased costs.

[0004] In the technology shown in Patent Document 1, the following method is disclosed: in an external air filter provided for inhaling compressed air, an existing sensor mounted on a compressor for detecting the pressure (discharge pressure) and temperature (discharge temperature) of the compressed air is used, and threshold values ​​are set for the detected temperature and pressure, thereby inferring the progress of blockage and determining blockage.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2021-14790 Summary of the invention

[0008] Technical problem to be solved by the invention

[0009] In the case of cooler blockage, due to insufficient cooling of the compressed air, according to the technology of Patent Document 1, the blockage of the cooler can be estimated based on the discharge temperature detected by the sensor. However, in the case where the discharge temperature changes due to other reasons such as the blockage of the suction filter, or when multiple coolers such as oil coolers are used, it is believed that the estimation accuracy of the blockage of the cooler becomes lower. In addition, by adding a sensor that detects the flow rate of the cooling air flowing in the cooler part and the pressure difference of the cooling air path, the blockage of the cooler can be estimated, but there is a problem of cost increase due to the addition of sensors, control changes for flow and pressure detection, and the addition of equipment.

[0010] Technical solutions to solve problems

[0011] The following is a solution to the above-mentioned problems.

[0012] A packaged air-cooled air compressor comprises: a compressor body; an electric motor driving the compressor body; a cooler cooling air compressed by the compressor body, the electric motor and the compressor body; and a housing accommodating the compressor body, the electric motor and the cooler.

[0013] The air compressor includes: a cooler duct, which separates a cooler cooling path from a motor cooling path and has an opening portion for merging the cooler cooling path and the motor cooling path, wherein the cooler cooling path cools the cooler by sucking in external air through a cooler air intake port provided in a shell, and the motor cooling path cools the motor by sucking in external air through a motor air intake port provided in the shell; and an exhaust port, which is provided in the shell and discharges the air of the cooler cooling path and the motor cooling path after merging through the opening portion to the outside of the shell.

[0014] The air compressor also includes: a first sensor for detecting the temperature of a load-side bearing of the motor; a second sensor for detecting the temperature of a bearing on the opposite side of the load; a control unit that calculates the 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; and a display unit that notifies a cleaning recommendation when the cooler is determined to be clogged.

[0015] In these technical solutions, the blockage of the cooler can be inferred using existing sensors, thereby suppressing cost increases and reporting recommendations for cooler cleaning at an appropriate time, by utilizing the fact that when the cooler is clogged, the cooling air volume passing through the cooling path of the cooler decreases while the cooling air volume passing through the cooling path of the motor increases, thereby reducing the temperature difference between the two bearings provided at the two axial ends of the motor.

[0016] Effects of the Invention

[0017] According to the present invention, by using an existing sensor provided in an air compressor to estimate cooler clogging, it is possible to suppress cost increases and recommend cooler cleaning at an appropriate timing. Other issues, structures, and effects than those described above will become clear from the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of an air-cooled oil-free screw compressor.

[0019] Figure 2 A diagram illustrating the cooling system structure and cooling air paths.

[0020] Figure 3 This is a graph showing the relationship between the cooling air volume and the motor bearing temperature difference.

[0021] Figure 4 It is a figure which shows the flowchart of a control apparatus. DETAILED DESCRIPTION

[0022] Hereinafter, specific embodiments of the present invention will be described based on the drawings.

[0023] Figure 1 This is a schematic diagram of an air-cooled oil-free screw compressor according to the present embodiment.

[0024] The air compressor 100 has a low-pressure stage compressor body 2 and a high-pressure stage compressor body 3 as a multi-stage compressor body. Each compressor body has a casing 5 that accommodates a pair of mutually meshing male and female screw rotors and a speed increasing gear 6 that drives the low-pressure stage compressor body 2 and the high-pressure stage compressor body 3 to rotate. In addition, the air compressor 100 is not limited to a structure in which the compressor body is composed of two stages.

[0025] The air compressor 100 also includes a motor 4 for driving each compressor, a compressed air intake port 50 for sucking in external air for compression, a cooler intake port 51 for sucking in external air for cooling the cooler, a motor intake port 52 for sucking in external air for cooling the motor, a low-pressure stage exhaust air cooler 10, a high-pressure stage exhaust air cooler 11, an oil cooler 12, a control unit 30 for controlling the motor 4, a display unit 31, and a housing 60 for storing them. The low-pressure stage exhaust air cooler 10, the high-pressure stage exhaust air cooler 11, and the oil cooler 12 are collectively referred to as coolers.

[0026] 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 side compressor body 2 and the high-pressure stage side compressor body 3 are respectively driven to rotate via a speed increasing gear 6 by a motor 4 serving as a driving source. The control unit 30 is composed of, for example, a CPU and a memory, and in addition to controlling the motor 4, it also performs display control of the display unit 31. The control unit 30 may also be composed of an FPGA or an ASIC instead of a CPU.

[0027] External air for compression is sucked in from the compressed air intake port 50 provided in the housing 60, and is supplied to the low-pressure stage compressor body 2 via the compressed air intake pipe 42 and the intake filter 1, and is compressed to a specified pressure. The compressed air that becomes high temperature is cooled by the low-pressure stage exhaust air cooler 10 and then supplied to the high-pressure stage compressor body 3. The air that becomes high temperature after being compressed to a specified pressure by the high-pressure stage compressor body 3 is cooled by the high-pressure stage exhaust air cooler 11 and then discharged to the outside 14 of the compressor. The low-pressure stage exhaust air cooler 10 and the high-pressure stage exhaust air cooler 11 are called air-cooled coolers. The path of the air that is sucked in for compression and discharged to the outside from the low-pressure stage compressor body 2 via the low-pressure stage exhaust air cooler 10 and from the high-pressure stage compressor body 3 via the high-pressure stage exhaust air cooler 11 is called a compression system.

[0028] The oil used for lubrication and cooling is supplied to the reservoir 17 of the gear case 5 , cooled by the oil cooler 12 via the oil pump 7 , and then branched into the lubrication path 15 and the cooling path 16 to be supplied to each device.

[0029] In the lubrication path 15, oil is supplied to the bearings of the speed increasing gear 6, the low-pressure stage compressor body 2, and the high-pressure stage side compressor body 3, and then recovered to the storage part 17 in the gear case 5. In the cooling path 16, oil is supplied to the sleeve part of the shell of each compressor body in the order of the high-pressure stage side compressor body 3 and the low-pressure stage compressor body 2, and then recovered to the storage part 17 in the gear case 5.

[0030] Cooling air from the low-pressure stage exhaust air cooler 10, the high-pressure stage exhaust air cooler 11, and the oil cooler 12 is sucked into the air compressor 100 from the cooler air intake port 51 provided in the housing 60. Cooling air for cooling the motor is sucked into the air compressor 100 from the motor air intake port 52 provided in the housing 60.

[0031] In the cooler cooling path, external air of the cooler cooling wind is sucked in from the cooler air intake port 51 by the cooling fan 13, and supplied to the low-pressure stage exhaust air cooler 10, the high-pressure stage exhaust air cooler 11, and the oil cooler 12 through the cooler duct 41 for respective cooling.

[0032] In the motor cooling path, the self-cooling fan provided on the cooling air intake side of the motor inhales the external air for cooling the motor from the motor air intake port 52. The inhaled external air passes through the motor cooling air intake duct (motor duct 40), and is sequentially supplied to the load-opposite side bearing 61, the housing, and the load-side bearing 62 provided on the motor 4, and the bearings are cooled individually via the bracket portion for storage. The air after the motor cooling is introduced into the cooler duct 41 from the opening 54 at the top of the cooler duct 41 together with the air that has become high temperature due to the compressor body 2, 3 and its piping, electrical components, etc., which are heat-generating bodies other than the cooler portion provided inside the air compressor 100. The air is discharged to the outside of the air compressor from the cooling air exhaust port 53 provided on the exhaust side of the cooling fan 13 together with the air after the cooler cooling.

[0033] The cooler cooling path and the motor cooling path are configured such that cooling air is sucked from the outside using different air intake ports (cooler air intake port 51 for cooler cooling air, motor air intake port 52 for motor cooling air) provided in the housing 60 of the air compressor 100, and discharged to the outside from a cooling air exhaust port 53 of the air compressor 100 through a common fan 13. The cooler duct 41 has the function of supplying external air to the low-pressure stage exhaust air cooler 10, the high-pressure stage exhaust air cooler 11, and the oil cooler 12 through the cooler air intake port 51, and is separated from the motor cooling path in the housing 60 of the air compressor 100.

[0034] In the motor 4 provided in the air compressor 100, for the purpose of protecting against fire or damage caused by temperature rise, a motor load-side bearing temperature sensor 20 is provided in the bracket portion that accommodates the load-side bearing 62, and a motor opposite-load-side bearing temperature sensor 21 is provided in the bracket portion that accommodates the opposite-load-side bearing 61. The temperature detected by each sensor is recorded in the control unit 30, and when the temperature exceeds a preset temperature, the compressor is stopped, and the main reason for the compressor stopping, such as "motor temperature abnormality", is displayed on the display unit 31.

[0035] Figure 2 The figure shows the arrangement of the low-pressure stage exhaust air cooler 10, the high-pressure stage exhaust air cooler 11, the oil cooler 12 (various coolers) and the equipment related to the cooling of the motor 4 and the outline of the flow of cooling air in the cooler cooling path and the motor cooling path of the present embodiment. The high-pressure stage exhaust air cooler 11 is provided on the entire surface in the depth direction of the paper surface, the low-pressure stage exhaust air cooler 10 is provided on the front side of the paper surface below the high-pressure stage exhaust air cooler 11, and the oil cooler 12 is provided on the rear side of the paper surface below the high-pressure stage exhaust air cooler 11.

[0036] like Figure 2 As shown, the cooling path of the air compressor 100 is divided into an upper cooler cooling path and a lower motor cooling path. The air intakes of the cooler cooling path and the motor cooling path inhale external air for cooling from two different cooler air intakes 51 and motor air intakes 52, respectively. However, at the opening 54 at the upper part of the cooler duct 41, the two paths (cooler cooling path and motor cooling path) merge, and the cooling air is discharged from a common cooling air exhaust port 53 by the fan 13.

[0037] Therefore, when the air volume passing through various coolers is reduced due to the blockage of various coolers, the air volume for cooling the motor is increased. That is, the flow rate of the cooler cooling path is reduced and the flow rate of the motor cooling path is increased. In the motor cooling path, the cooling air for the motor cools the load-side bearing 62 and the opposite-load-side bearing 61, but structurally, it is easy to cool the opposite-load-side bearing 61, so there is a tendency for the load-side bearing 62 to become high temperature. Therefore, when the cooling air volume increases, the same cooling effect as the opposite-load-side bearing 61 can be obtained at the load-side bearing 62, so the temperature difference between the bearings becomes smaller. These characteristics are used to determine the blockage of the cooler.

[0038] Figure 3 It is a graph showing the relationship between the cooling air volume of the motor 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 bearing temperature sensor 21 on the opposite side of the load from the temperature Tf detected by the load-side bearing temperature sensor 20. During normal operation without clogging of various coolers, the bearing temperature difference Tfb becomes larger. However, when clogging of various coolers occurs and the cooling air volume of the motor increases, the bearing temperature difference Tfb becomes smaller. That is, when the clogging of the cooler intensifies and the bearing temperature difference Tfb is less than the threshold, the control unit 30 determines that the cooler is blocked, and displays "cooler cleaning" and the like for recommending cooler cleaning through the display unit 31. The blockage of the cooler determined by the control unit 30 refers to the state in which any one or two of the low-pressure exhaust air cooler 10, the high-pressure exhaust air cooler 11, and the oil cooler 12, or all of them are blocked.

[0039] Here, the advantage of using the bearing temperature difference to judge the blockage of the cooler is that the bearing temperature changes according to the rotation speed and current of the motor, the load condition of the compressor body, and the temperature of the outside air, but these influences can be eliminated by setting it as the temperature difference between the load-side bearing 61 and the load-side bearing 62. In addition, the temperature difference is not limited to the bearing, and a temperature sensor used in other heat-generating parts (such as a coil) can also be used.

[0040] The blockage judgment of the cooler of this embodiment is only applicable when the operating state of the air compressor 100 is load operation. The reason is that the load of the compressor body 2, 3 is low during unload operation, so the bearing temperature of the load-opposite side bearing 61 and the load-side bearing 62 becomes lower, and the temperature difference becomes smaller. However, when unloading, the temperature of the compressed air and oil cooled by the cooler cooling path becomes lower, so even if the cooler is blocked and is not cleaned, there will be no particular problem, so it is considered that blockage judgment is not necessary. Here, load operation refers to a state of operation while discharging compressed air accompanied by a load. On the other hand, unloading operation refers to a state of operation at a low load while discharging a small amount of intake air in order not to stop the compressor.

[0041] Figure 4 When the control of the control unit 30 starts in step S40, first, in step S41, the control unit 30 determines whether the operation state of the air compressor 100 is loaded operation or unloaded operation, and in the case of loaded operation, the process moves to step S42.

[0042] In step S42, the temperature Tf detected by the load-side bearing temperature sensor 20 and the temperature Tb detected by the opposite-load-side bearing temperature sensor 21 are detected. In addition, even if the order of step S41 and step S42 is reversed, there is no problem, and the temperature detection based on the load-side bearing temperature sensor 20 and the opposite-load-side bearing temperature sensor 21 can also be performed in an operating state other than load operation.

[0043] In step S43 , the control unit 30 calculates the bearing temperature difference Tfb=Tf−Tb based on the temperature detected in step S42 .

[0044] In step S44, the control unit 30 determines whether the bearing temperature difference Tfb is less than a predetermined threshold value. If the bearing temperature difference Tfb is less than the predetermined threshold value, the process proceeds to step S45. Otherwise, the process returns to step S42 to perform temperature detection. In this step, it may also be determined that the bearing temperature difference Tfb is less than a predetermined threshold value. In short, the predetermined threshold value is pre-stored in the memory (not shown) of the control unit 30.

[0045] In step S45 , the control unit 30 outputs a warning signal of the blockage of the cooler to the display unit 31 .

[0046] In step S46, the display unit 31 displays "Clean the cooler" to recommend cleaning the cooler based on the warning signal output from the control unit 30. This display may be in other forms as long as it can recommend cleaning the cooler to the user.

[0047] As described above, according to this embodiment, by estimating cooler clogging using the existing sensors of the air compressor 100, namely, the counter-load side bearing temperature sensor 21 and the load side bearing temperature sensor 20, cost increases can be suppressed and cooler cleaning can be recommended at an appropriate timing.

[0048] Furthermore, this embodiment describes an air-cooled oil-free screw compressor, but the determination of cooler clogging in the present invention can also be applied to an oil-cooled air compressor or a single-stage or multi-stage air compressor.

[0049] Description of Reference Numerals

[0050] 1: Suction filter,

[0051] 2: Low-pressure stage compressor body,

[0052] 3: High-pressure stage compressor body,

[0053] 4: Electric motor,

[0054] 5: Gear box,

[0055] 6: Speed ​​increasing gear,

[0056] 7: Oil pump,

[0057] 10: Cooler for exhaust air at low pressure stage,

[0058] 11: Cooler for high pressure exhaust air,

[0059] 12: Oil cooler,

[0060] 13: Cooling fan,

[0061] 15: Lubrication path,

[0062] 16: Cooling path,

[0063] 17: Storage Department,

[0064] 20: Temperature sensor for motor load side bearing,

[0065] 21: Temperature sensor for the bearing on the opposite side of the motor load,

[0066] 30: Control Department,

[0067] 31: Display unit,

[0068] 40: Motor cooling air intake duct,

[0069] 41: Cooler pipe,

[0070] 42: Suction pipe for compressed air,

[0071] 50: Inlet for compressed air,

[0072] 51: Cooler air intake for cooler cooling air,

[0073] 52: Motor cooling air intake port,

[0074] 53: Cooling air exhaust port,

[0075] 54: Opening on the top of the cooler pipe,

[0076] 60: Shell,

[0077] 100: Air compressor.

Claims

1. An air compressor comprising: a compressor body; a motor for driving the compressor body; a cooler for cooling air compressed by the compressor body, the motor and the compressor body; and a housing for accommodating the compressor body, the motor and the cooler, wherein the air compressor comprises: a cooler duct separating a cooler cooling path from a motor cooling path and having an opening for merging the cooler cooling path and the motor cooling path, wherein the cooler cooling path cools the cooler by sucking in external air through a cooler air intake port provided in the housing, and the motor cooling path cools the motor by sucking in external air through a motor air intake port provided in the housing; an exhaust port provided in the housing to discharge the air of the cooler cooling path and the motor cooling path after the air flows through the opening to the outside of the housing; a first sensor for detecting a temperature of a load-side bearing of the motor and a second sensor for detecting a temperature of an opposite-load-side bearing; The control unit calculates a temperature difference between the first sensor and the second sensor, and determines that the cooler is clogged when the temperature difference is smaller than a threshold value.

2. The air compressor according to claim 1, characterized in that: A display unit is provided. When the control unit determines that the cooler is clogged, the control unit outputs a warning signal to the display unit. The display unit performs a display for recommending cooler cleaning based on the warning signal from the control unit.

3. The air compressor according to claim 2, characterized in that: The control unit determines whether the air compressor is in load operation, calculates a temperature difference between the first sensor and the second sensor when the air compressor is in load operation, and determines that the cooler is clogged when the temperature difference is smaller than a threshold value.

4. The air compressor according to claim 3, characterized in that: The compressor body is a multi-stage structure of a low-pressure stage side compressor body and a high-pressure stage side compressor body.

5. The air compressor according to claim 3, characterized in that: The cooler has: an air cooler for cooling the air compressed by the compressor body; and An oil cooler cools the electric motor and the compressor body.

6. The air compressor according to claim 5, characterized in that: The compressor body is a multi-stage structure of a low-pressure stage side compressor body and a high-pressure stage side compressor body. The air cooler includes: a low-pressure exhaust air cooler for cooling compressed air from the low-pressure side compressor body; and a high-pressure exhaust air cooler for cooling compressed air from the high-pressure side compressor body.

7. An air compressor comprising: Compressor body; an electric motor driving the compressor body; an air cooler for cooling the air compressed by the compressor body; an oil cooler for cooling the electric motor and the compressor body; and a housing for accommodating the compressor body, the electric motor, the air cooler, and the oil cooler, The air compressor is characterized in that The housing has: A cooler air intake port for taking in external air used for cooling the air cooler and the oil cooler; and an air intake port for the motor for taking in external air used for cooling the motor, The air compressor has a cooler duct in the housing, the cooler duct separating a cooler cooling path from a motor cooling path, the cooler cooling path cooling the air cooler and the oil cooler using air sucked from the cooler air intake port, and the motor cooling path cooling the motor using air sucked from the motor air intake port, The cooler pipe has an opening portion that allows the cooler cooling path and the motor cooling path to merge. The air compressor has a cooling air exhaust port for exhausting the air in the cooler cooling path and the motor cooling path that have merged through the opening to the outside of the air compressor. And has: a first sensor for detecting a temperature of a load-side bearing of the motor and a second sensor for detecting a temperature of an opposite-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; and A display unit for displaying a recommendation for cleaning the cooler based on the warning signal from the control unit.

Images