Drain amount estimation device

Abstract

Provided is a drain amount estimation device capable of quickly estimating the amount of drain mixed in oil.　This drain amount estimation device for estimating the amount of drain mixed in oil that exchanges heat with a cooling medium by an oil cooler 8 comprises: an oil temperature sensor 11A for detecting the oil temperature on the upstream side of the oil cooler 8; an oil temperature sensor 11B for detecting an oil temperature on the downstream side of the oil cooler 8; and a calculation device 12 for calculating the change amount ΔTA of the oil temperature caused by the oil cooler 8 on the basis of detection results of the oil temperature sensors 11A, 11B, and calculating the amount of drain mixed in the oil on the basis of the change amount ΔTA of the oil temperature.

Description

Drain volume estimation device

[0001] The present invention relates to a drain amount estimation device that estimates the amount of drain mixed in oil that is heat exchanged with a cooling medium by a heat exchanger.

[0002] Patent Document 1 discloses a refrigeration system including a compressor that compresses a refrigerant (gas phase) mixed with lubricating oil, an oil separator that separates the refrigerant compressed by the compressor from the lubricating oil, a condenser that condenses the refrigerant separated by the oil separator, an expansion valve that expands the refrigerant (liquid phase) condensed by the condenser, an evaporator that evaporates the refrigerant expanded by the expansion valve, a first line that supplies the refrigerant (gas phase) evaporated by the evaporator to the compressor, and a second line that supplies the lubricating oil separated by the oil separator to the first line.

[0003] The second line has a moisture indicator that detects the amount of moisture (drainage) mixed in the lubricating oil, and a heat exchanger that is located upstream of the moisture indicator and cools the lubricating oil. By lowering the temperature of the lubricating oil using the heat exchanger, thermal damage to the moisture indicator is prevented and the sensitivity of the moisture indicator is increased.

[0004] Japanese Patent Application Laid-Open No. 2002-181420

[0005] As described in Patent Document 1, when a moisture indicator having an adsorbent is used to detect the amount of drain mixed in oil, it is necessary to wait for the adsorbent to dry before repeating the detection, and rapid detection is not possible.

[0006] An object of the present invention is to quickly estimate the amount of drainage mixed into oil.

[0007] In order to solve the above problem, the configurations described in the claims are applied. The present invention includes a plurality of means for solving the above problem, and one example thereof is a drain amount estimation device that estimates the amount of drain mixed in oil that is heat exchanged with a cooling medium by a heat exchanger, the drain amount estimation device comprising: a first oil temperature sensor that detects the temperature of the oil upstream of the heat exchanger; a second oil temperature sensor that detects the temperature of the oil downstream of the heat exchanger; and a computing device that calculates an amount of change in the oil temperature by the heat exchanger based on detection results of the first and second oil temperature sensors, and calculates the amount of drain mixed in the oil based on the amount of change in the oil temperature.

[0008] According to the present invention, the amount of drainage mixed in oil can be quickly estimated.

[0009] Problems, configurations, and effects other than those described above will become clear from the following description.

[0010] FIG. 1 is a diagram showing the configuration of an oil-lubricated air compressor according to a first embodiment of the present invention. FIG. 2 is a diagram showing a specific example of a calculation table according to the first embodiment of the present invention. FIG. 3 is a diagram showing the configuration of an oil-lubricated air compressor according to a second embodiment of the present invention. FIG. 4 is a diagram showing a specific example of a calculation table according to the second embodiment of the present invention. FIG. 5 is a diagram showing the configuration of an oil-lubricated air compressor according to a third embodiment of the present invention. FIG. 6 is a diagram showing a specific example of a calculation table according to the third embodiment of the present invention. FIG. 7 is a diagram showing the configuration of an oil-lubricated air compressor according to a fourth embodiment of the present invention. FIG. 8 is a diagram showing a specific example of a calculation table according to the fourth embodiment of the present invention.

[0011] A first embodiment of the present invention will be described with reference to the drawings, taking an oil-lubricated air compressor as an example of an application of the present invention.

[0012] FIG. 1 is a diagram showing the configuration of an oil-lubricated air compressor according to this embodiment.

[0013] The oil-lubricated air compressor of this embodiment includes an electric motor 1, a compressor main body 2 that is driven by the electric motor 1 and compresses air while injecting oil into a working chamber, an air filter 3 that is provided on the suction side of the compressor main body 2 and removes foreign matter from the air, a separator 4 that separates oil from the compressed air discharged from the compressor main body 2, an oil pipe 5 that supplies the oil separated in the separator 4 to the working chamber of the compressor main body 2, and a compressed air pipe 6 that supplies the compressed air separated in the separator 4 to equipment (not shown) that consumes the air.

[0014] The compressor body 2 has, for example, a pair of intermeshing male and female screw rotors and a casing that houses the screw rotors, with multiple working chambers formed in the tooth grooves of the screw rotors. Each working chamber moves axially as the rotor rotates, and sequentially performs an intake process to draw in air, a compression process to compress the air, and a discharge process to discharge the compressed air. The compressor body 2 is designed to inject oil into the working chambers for the purposes of cooling the heat of compression, sealing the working chambers, and lubricating the rotors.

[0015] The separator 4 has, for example, a swirl flow path that swirls the compressed air, separates oil from the compressed air by centrifugal separation, and stores the separated oil. However, if moisture in the air condenses and generates drainage, the drainage will be mixed with the oil. The oil piping 5 is provided with an oil filter 7 that removes foreign matter from the oil, an oil cooler 8 (heat exchanger), and the like. A cooling medium (e.g., cooling water) is supplied to the oil cooler 8 through a cooling medium line 9, and the oil is cooled by heat exchange with the cooling medium. The compressed air piping 6 is provided with an aftercooler 10. A cooling medium is supplied to the aftercooler 10 through the cooling medium line 9, and the aftercooler 10 cools the compressed air by heat exchange with the cooling medium.

[0016] The oil-lubricated air compressor of this embodiment is equipped with a drain amount estimation device that estimates the amount of drain mixed in the oil that is heat exchanged with the cooling medium by the oil cooler 8. The oil-lubricated air compressor of this embodiment is equipped with, as components that constitute the drain amount estimation device, an oil temperature sensor 11A (first oil temperature sensor) that detects the temperature of the oil on the upstream side (oil inlet side) of the oil cooler 8, an oil temperature sensor 11B (second oil temperature sensor) that detects the temperature of the oil on the downstream side (oil outlet side) of the oil cooler 8, and a calculation device 12.

[0017] The arithmetic unit 12 includes a processor that executes calculations and control according to a program, and a memory that stores the program and data. The arithmetic unit 12 calculates the amount of change (drop) ΔTA in the oil temperature caused by the oil cooler 8 based on the detection results of the oil temperature sensors 11A and 11B. Then, the arithmetic unit 12 calculates the amount of drainage mixed into the oil based on the amount of change ΔTA in the oil temperature. More specifically, the arithmetic unit 12 stores, for example, a calculation table (see FIG. 2 ) that indicates the relationship between the amount of change in the oil temperature caused by the oil cooler 8 and the amount of drainage mixed into the oil, and uses this calculation table to calculate the amount of drainage from the calculated amount of change ΔTA in the oil temperature.

[0018] The above-described calculation table is based on the idea that the greater the amount of drain mixed in the oil, the greater the heat capacity of the mixture of oil and drain, and the smaller the amount of change in oil temperature caused by the oil cooler 8. The calculation table may be created based on data measured using a test compressor, or may be created using a heat balance calculation formula. However, the amount of change in cooling medium temperature and oil pressure caused by the oil cooler 8 uses representative values ​​(fixed values).

[0019] The computing device 12 displays the calculated amount of drain on the monitor 13, or if the calculated amount of drain is equal to or greater than a predetermined value, displays a warning message on the monitor 13. This prompts the user to remove the drain or change the oil.

[0020] In the present embodiment described above, the amount of drainage mixed in the oil can be detected more quickly than when a moisture indicator having an adsorbent is used, and the estimation accuracy of the amount of drainage can be improved.

[0021] A second embodiment of the present invention will be described with reference to the drawings. In this embodiment, parts equivalent to those in the first embodiment are given the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0022] FIG. 3 is a diagram showing the configuration of an oil-lubricated air compressor according to this embodiment.

[0023] The oil-lubricated air compressor of this embodiment is equipped with, as components constituting the drain amount estimation device, in addition to the oil temperature sensors 11A, 11B and the calculation device 12 described above, a cooling medium temperature sensor 14A (first cooling medium temperature sensor) that detects the temperature of the cooling medium on the upstream side (cooling medium inlet side) of the oil cooler 8, and a cooling medium temperature sensor 14B (second cooling medium temperature sensor) that detects the temperature of the cooling medium on the downstream side (cooling medium outlet side) of the oil cooler 8.

[0024] As in the first embodiment, the calculation device 12 calculates the amount of change ΔTA in the oil temperature caused by the oil cooler 8 based on the detection results of the oil temperature sensors 11A, 11B. Also, based on the detection results of the cooling medium temperature sensors 14A, 14B, the calculation device 12 calculates the amount of change (rise) ΔTB in the cooling medium temperature caused by the oil cooler 8. Then, based on the amount of change ΔTA in the oil temperature and the amount of change ΔTB in the cooling medium temperature, the calculation device 12 calculates the amount of drainage mixed into the oil.

[0025] More specifically, the calculation device 12 stores a calculation table (see FIG. 4 ) showing the relationship between the amount of change in oil temperature caused by the oil cooler 8 and the amount of drain mixed into the oil for each condition where the amount of change in cooling medium temperature caused by the oil cooler 8 is ΔTBa, ΔTBb (where ΔTBb<ΔTBa), or ΔTBc (where ΔTBc>ΔTBa), for example. Then, using the calculation table described above, the amount of drain is calculated from the calculated amount of change in oil temperature ΔTA and amount of change in cooling medium temperature ΔTB.

[0026] In this embodiment, the amount of drainage mixed in the oil can be detected quickly, as in the first embodiment, and the estimation accuracy of the drainage amount can be improved compared to the first embodiment.

[0027] A third embodiment of the present invention will be described with reference to the drawings. In this embodiment, parts equivalent to those in the first embodiment are given the same reference numerals, and descriptions thereof will be omitted where appropriate.

[0028] FIG. 5 is a diagram showing the configuration of an oil-lubricated air compressor according to this embodiment.

[0029] The oil-lubricated air compressor of this embodiment is equipped with, as devices constituting the drain amount estimation device, in addition to the oil temperature sensors 11A, 11B and the calculation device 12 described above, an oil pressure sensor 15A (first oil pressure sensor) that detects the oil pressure on the upstream side (oil inlet side) of the oil cooler 8, and an oil pressure sensor 15B (second oil pressure sensor) that detects the oil pressure on the downstream side (oil outlet side) of the oil cooler 8.

[0030] As in the first embodiment, the calculation device 12 calculates the amount of change ΔTA in oil temperature caused by the oil cooler 8 based on the detection results of the oil temperature sensors 11A, 11B. Also, based on the detection results of the oil pressure sensors 15A, 15B, the calculation device 12 calculates the amount of change ΔP in oil pressure (pressure loss) caused by the oil cooler 8. Then, based on the amount of change ΔTA in oil temperature and the amount of change ΔP in oil pressure, the calculation device 12 calculates the amount of drainage mixed into the oil.

[0031] More specifically, the calculation device 12 stores a calculation table (see FIG. 6 ) showing the relationship between the amount of change in oil temperature caused by the oil cooler 8 and the amount of drain mixed into the oil for each condition where the amount of change in oil pressure caused by the oil cooler 8 is ΔPa, ΔPb (where ΔPb<ΔPa), or ΔPc (where ΔPc>ΔPa), for example. Then, using the calculation table described above, the amount of drain is calculated from the calculated amount of change in oil temperature ΔTA and amount of change in oil pressure ΔP.

[0032] In this embodiment, the amount of drainage mixed in the oil can be detected quickly, as in the first embodiment, and the estimation accuracy of the drainage amount can be improved compared to the first embodiment.

[0033] A fourth embodiment of the present invention will be described with reference to the drawings. In this embodiment, parts equivalent to those in the first to third embodiments are given the same reference numerals, and descriptions thereof will be omitted where appropriate.

[0034] FIG. 7 is a diagram showing the configuration of an oil-lubricated air compressor according to this embodiment.

[0035] The oil-lubricated air compressor of this embodiment includes the above-mentioned oil temperature sensors 11A, 11B, cooling medium temperature sensors 14A, 14B, oil pressure sensors 15A, 15B, and a calculation device 12 as components that constitute the drain amount estimation device.

[0036] As in the first embodiment, the calculation device 12 calculates the amount of change ΔTA in the oil temperature caused by the oil cooler 8 based on the detection results of the oil temperature sensors 11A, 11B. Also, as in the second embodiment, the calculation device 12 calculates the amount of change ΔTB in the coolant temperature caused by the oil cooler 8 based on the detection results of the coolant temperature sensors 14A, 14B. Also, as in the third embodiment, the calculation device 12 calculates the amount of change ΔP in the oil pressure caused by the oil cooler 8 based on the detection results of the oil pressure sensors 15A, 15B. Then, the calculation device 12 calculates the amount of drainage mixed into the oil based on the amount of change ΔTA in the oil temperature, the amount of change ΔTB in the coolant temperature, and the amount of change ΔP in the oil pressure.

[0037] More specifically, the calculation device 12 stores a calculation table (see FIG. 8) that shows the relationship between the amount of change in oil temperature caused by the oil cooler 8 and the amount of drain mixed into the oil for each condition where the amount of change in the temperature of the cooling medium caused by the oil cooler 8 and the amount of change in the oil pressure are different. Then, using the calculation table described above, the amount of drain is calculated from the calculated amount of change in oil temperature ΔTA, amount of change in cooling medium temperature ΔTB, and amount of change in oil pressure ΔP.

[0038] In this embodiment, similar to the first to third embodiments, the amount of drain mixed in the oil can be detected quickly, and the estimation accuracy of the drain amount can be improved compared to the first to third embodiments.

[0039] Although the drain amount estimation device of the present invention has been described above as being applicable to an oil-lubricated air compressor, the present invention is not limited to this. For example, the drain amount estimation device of the present invention may be applied to the refrigeration system described in Patent Document 1 instead of the moisture indicator.

[0040] 8...Oil cooler (heat exchanger), 11A...oil temperature sensor (first oil temperature sensor), 11B...oil temperature sensor (second oil temperature sensor), 12...arithmetic unit, 14A...cooling medium temperature sensor (first cooling medium temperature sensor), 14B...cooling medium temperature sensor (second cooling medium temperature sensor), 15A...oil pressure sensor (first oil pressure sensor), 15B...oil pressure sensor (second oil pressure sensor)

Claims

1. A drain amount estimation device that estimates the amount of drain mixed in oil that is heat exchanged with a cooling medium by a heat exchanger, comprising: a first oil temperature sensor that detects the temperature of the oil upstream of the heat exchanger; a second oil temperature sensor that detects the temperature of the oil downstream of the heat exchanger; and a calculation device that calculates the amount of drain mixed in the oil based on the detection results of the first and second oil temperature sensors, and calculates the amount of drain mixed in the oil based on the amount of change in the oil temperature.

2. A drain amount estimation device as defined in claim 1, further comprising a first cooling medium temperature sensor that detects the temperature of the cooling medium upstream of the heat exchanger, and a second cooling medium temperature sensor that detects the temperature of the cooling medium downstream of the heat exchanger, wherein the calculation device calculates the amount of change in temperature of the cooling medium caused by the heat exchanger based on the detection results of the first and second cooling medium temperature sensors, and calculates the amount of drain mixed in the oil based on the amount of change in temperature of the oil and the amount of change in temperature of the cooling medium.

3. A drain amount estimation device as claimed in claim 1, further comprising a first oil pressure sensor that detects the pressure of the oil upstream of the heat exchanger, and a second oil pressure sensor that detects the pressure of the oil downstream of the heat exchanger, wherein the arithmetic unit calculates the amount of change in the oil pressure caused by the heat exchanger based on the detection results of the first and second oil pressure sensors, and calculates the amount of drain mixed into the oil based on the amount of change in the oil temperature and the amount of change in the oil pressure.

4. A drain amount estimation device as claimed in claim 2, further comprising a first oil pressure sensor that detects the pressure of the oil upstream of the heat exchanger, and a second oil pressure sensor that detects the pressure of the oil downstream of the heat exchanger, wherein the arithmetic unit calculates the amount of change in the oil pressure caused by the heat exchanger based on the detection results of the first and second oil pressure sensors, and calculates the amount of drain mixed into the oil based on the amount of change in the oil temperature, the amount of change in the temperature of the cooling medium, and the amount of change in the oil pressure.

Images