Structure for discharging residual lubricating oil on the primary side of an oil filter in an oil-flooded compressor

Abstract

To prevent overflowing of a residual lubrication oil at the primary side of an oil filter during replacement of the lubrication oil and replacement of the oil filter to improve maintainability in an oil cooling type compressor in which an oil cooler is disposed at a higher position than the oil filter.SOLUTION: An oil cooling type compressor includes a compressor body 10, a receiver tank 11, and an oil cooler 12. In the oil cooling compressor, a lubrication oil circulation system which supplies lubrication oil cooled by the oil cooler 12 to the compressor body 10 via an oil filter 20 again is formed. Further, the oil cooler 12 is disposed at a position higher than the oil filter 20. In the oil cooling type compressor, an oil discharge passage 50 which is branched from a lower end of a primary side passage of the oil filter 20 and discharges the lubrication oil at the primary side of the oil filter is formed, and opening / closing means 51 which can open or close the oil discharge passage 50 is provided.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a structure for discharging residual oil on the primary side of an oil filter included in a lubricating oil circulation system in an oil-cooled compressor in which the lubricating oil circulation system is formed. [Background technology]

[0002] A conventional oil-cooled compressor 70 that compresses the compressed gas together with lubricating oil for cooling, lubrication, and sealing comprises, as shown in Figure 7, a compressor main body 71 that compresses the compressed gas together with lubricating oil and discharges it, a receiver tank 72 that introduces the compressed gas discharged from the compressor main body 71 and separates it into the compressed gas and lubricating oil (primary separation), and an oil cooler 73 that cools the lubricating oil recovered in the receiver tank 72, and a lubricating oil circulation system is formed in which the lubricating oil cooled by this oil cooler 73 is supplied again into the working space of the compressor main body 71 via an oil filter 74 (Patent Document 1).

[0003] The oil-cooled compressor 70 has a pipe 76 connecting the compressor body 71 and the receiver tank 72, a pipe 77 connecting the receiver tank 72 and the oil cooler 73, a pipe 78 connecting the oil cooler 73 and the oil filter 74, and a pipe 79 connecting the oil filter 74 and the compressor body 71 (see Figure 7).

[0004] In addition, this oil-cooled compressor 70 is formed with an intake system that introduces air, which is the gas to be compressed, into the intake port of the compressor main body 71 via an air filter 81 and an intake valve 82, and a compressed gas supply system is formed in which the compressed gas after gas-liquid separation (primary separation) in the aforementioned receiver tank 72 is further passed through a separator (not shown) to remove any remaining lubricating oil in the compressed gas, and then the compressed gas is supplied to the consumer side to which an air work machine, etc., not shown, is connected via supply piping 84 equipped with an aftercooler 83, etc., and these components are housed and packaged in a soundproof box together with a driving source 85 such as a motor or engine that drives the compressor main body 71 (a motor in the illustrated example) (see Figure 7).

[0005] Furthermore, in the above-mentioned oil-cooled compressor 70, the oil cooler 73 is disposed opposite the exhaust port provided on the top plate of the soundproof box, and as a result, the oil cooler 73 is disposed at a relatively high position within the soundproof box compared to other components such as the receiver tank 72 that stores lubricating oil.

[0006] As mentioned above, oil-flooded compressors circulate the lubricating oil used for cooling, sealing, and lubrication, and as the oil oxidizes and becomes contaminated over time, its performance deteriorates. For this reason, the lubricating oil in oil-flooded compressors must be replaced at scheduled maintenance intervals.

[0007] On the other hand, if deteriorated lubricating oil is mixed with new lubricating oil and used, the new lubricating oil will deteriorate more quickly due to the influence of the properties of the deteriorated lubricating oil. Therefore, for example, when replacing the lubricating oil in the oil-cooled compressor 70 of Patent Document 1 mentioned above, it is necessary to drain not only the lubricating oil stored in the receiver tank 72, but also the lubricating oil stored in equipment other than the receiver tank 72.

[0008] However, as described above, the oil-cooled compressor 70 is arranged so that the oil cooler 73 is above the receiver tank 72, i.e., specifically, so that the bottom of the oil cooler 73 is higher than the upper limit of the oil level in the receiver tank 72. Therefore, when the oil-cooled compressor 70 is stopped and the pressure in the receiver tank 72 drops to atmospheric pressure or a pressure close to atmospheric pressure, the lubricating oil in the oil cooler 73 flows back into the receiver tank 72 through the piping 77 connecting the receiver tank 72 and the oil cooler 73 and is recovered. However, the backflow of lubricating oil through the piping 77 does not allow the entire amount of lubricating oil in the oil cooler 73 to be recovered, and the lubricating oil will still remain in the oil cooler 73.

[0009] Therefore, the oil-cooled compressor 70 of the above-mentioned Patent Document 1 is structured so that the lubricating oil stored in the oil cooler 73 can be discharged to the receiver tank 72. Specifically, as shown in FIG. 7, a tank oil discharge port 91 is provided at the bottom of the receiver tank 72 which communicates with the internal space of the receiver tank 72, a tank oil discharge piping 92 connected below the tank oil discharge port 91, and a tank oil discharge port opening / closing means 93 for opening and closing the tank oil discharge port 91 is provided at the bottom of the oil cooler 73. A cooler oil drain port 96 is provided in the oil cooler side drain means 95, which is equipped with a cooler drain valve 97 below the cooler oil drain port 96 for opening and closing the cooler oil drain port 96, and the secondary side of the cooler drain valve 97 provided in the cooler side oil drain means 95 is connected to the space within the receiver tank 72.By simply opening the cooler drain valve 97 and the tank oil drain opening and closing means 93, lubricating oil can be smoothly drained from both the oil cooler 73 and the receiver tank 72 through the single oil discharge port 94 provided in the tank side oil drain means 90. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 6168877 Summary of the Invention [Problem to be solved by the invention]

[0011] However, in the oil-cooled compressor 70 disclosed in the above-mentioned Patent Document 1, even though the lubricating oil could be extracted from both the oil cooler 73 and the receiver tank 72, the lubricating oil still remained in the piping 78 between the oil cooler 73 and the oil filter 74 (the primary side of the oil filter 74).

[0012] Typically, the oil filter 74 is detachably attached to, for example, a filter mounting fixture and connected to the piping 78 and the piping 79 via the filter mounting fixture, so that it is possible to drain the lubricating oil in the piping 78 by removing the oil filter 74. However, the oil-cooled compressor 70 disclosed in the above-mentioned Patent Document 1 is configured such that the oil cooler 73 is positioned above the oil filter 74. Therefore, when the oil filter 74 is removed, the lubricating oil that had accumulated in the piping 78 between the oil cooler outlet side 73b and the oil filter 74 (in the primary side of the oil filter 74) overflows from the filter mounting fixture all at once, contaminating the interior of the machine, resulting in poor maintainability. This problem occurred not only when changing the lubricating oil as described above, but also when changing the oil filter.

[0013] Therefore, the present invention has been developed to solve the problems in the above-mentioned conventional technology, and aims to provide a discharge structure for residual lubricating oil on the primary side of the oil filter in an oil-cooled compressor in which the oil cooler is located above the oil filter as described above, which prevents the residual lubricating oil on the primary side of the oil filter from overflowing when changing the lubricating oil or the oil filter, and enables improved maintainability. [Means for solving the problem]

[0014] The means for solving the problems are described below together with the reference numerals used in the description of the embodiment of the invention. These reference numerals are intended to clarify the correspondence between the description of the claims and the description of the embodiment of the invention, and needless to say, are not used to restrict the interpretation of the technical scope of the present invention.

[0015] In order to achieve the above object, the discharge structure of residual lubricating oil on the primary side of the oil filter in the oil-cooled compressor 1 of the present invention comprises a compressor body 10 that discharges compressed gas together with lubricating oil supplied into an internal working space, a receiver tank 11 that introduces the compressed gas discharged by the compressor body 10 and separates the gas and liquid, and an oil cooler 12 that cools the lubricating oil separated in the receiver tank 11, a lubricating oil circulation system is formed in which the lubricating oil cooled in the oil cooler 12 is supplied again to the compressor body 10 via an oil filter 20, and in the oil-cooled compressor 1 in which the oil cooler 12 is arranged above the oil filter 20, The secondary side of the oil cooler and The oil filter 20 branches off from the lower end of the primary side flow passage, The secondary side of the oil cooler and An oil drain passage 50 is formed to drain the lubricating oil from the primary side of the oil filter 20, and , The oil discharge passage 50 is characterized by being provided with an opening / closing means 51 (a valve 51 in FIGS. 1, 2, and 6) that can open and close the oil discharge passage 50 (claim 1: see FIGS. 1 to 6).

[0016] The bottom of the oil cooler 12 may be disposed higher than the upper limit of the oil level in the receiver tank 11, and the oil drain passage 50 may be connected to the receiver tank 11. (Claim 2: see Figs. 1 and 2).

[0017] The oil drain passage 50 may be designed to lead to the outside of the aircraft (claim 3: see FIG. 6).

[0018] The oil filter 20 may be attached to a filter mounting fixture 30, and the oil drain passage 50 may be formed branching off from the filter mounting fixture 30 located at the lower end of the primary side passage of the oil filter 20 (Claim 4: see Figure 5). [Effects of the Invention]

[0019] The discharge structure for residual lubricating oil on the primary side of the oil filter in the oil-cooled compressor of the present invention described above provides a means for draining deteriorated lubricating oil accumulated in the primary side flow path of the oil filter 20 by opening the oil discharge flow path 50 during oil change without removing the oil filter 20.

[0020] Furthermore, due to the discharge structure of the residual lubricating oil on the primary side of the oil filter in the oil-cooled compressor of the present invention, when replacing the oil filter 20, the oil discharge passage 50 can be opened when removing the oil filter 20, thereby preventing the overflow of residual lubricating oil accumulated in the primary passage of the oil filter. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic circuit diagram showing a first embodiment of the present invention. [Figure 2] 3 is a diagram illustrating a discharge structure for residual lubricating oil on the primary side of the oil filter in the first embodiment. FIG. [Figure 3] 3A is an enlarged view of the filter mounting fixture 30 in FIG. 2, and FIG. 3B is a cross-sectional view of FIG. [Figure 4] FIG. 3 is a diagram illustrating the flow of lubricating oil flowing from the primary side of the oil filter 20 in the first embodiment. [Figure 5] 10A is an enlarged view of a filter attachment part 30 in the second embodiment, and FIG. 10B is a cross-sectional view of FIG. [Figure 6] 10 is a diagram illustrating a discharge structure for residual lubricating oil on the primary side of an oil filter in a third embodiment. FIG. [Figure 7] FIG. 1 is a schematic circuit diagram of a conventional oil-cooled compressor. DETAILED DESCRIPTION OF THE INVENTION

[0022] First, a first embodiment of the present invention will be described below with reference to the accompanying drawings.

[0023] In FIG. 1, reference numeral 1 denotes an oil-cooled compressor that compresses gas to be compressed together with lubricating oil for cooling, lubrication, and sealing.

[0024] As shown in Figure 1, the oil-cooled compressor 1 comprises a compressor main body 10 that compresses and discharges the compressed gas together with lubricating oil, a receiver tank 11 that introduces the compressed gas discharged from the compressor main body 10 and separates it into the compressed gas and lubricating oil (primary separation), and an oil cooler 12 that cools the lubricating oil recovered in the receiver tank 11, and a lubricating oil circulation system is formed in which the lubricating oil cooled by this oil cooler 12 is supplied again into the working space of the compressor main body 10 via an oil filter 20.

[0025] The oil-cooled compressor 1 also has a pipe 41 connecting the compressor main body 10 and the receiver tank 11, a pipe 42 connecting the receiver tank 11 and the oil cooler 12, a pipe 43 connecting the oil cooler 12 and the oil filter 20, and a pipe 44 connecting the oil filter 20 and the compressor main body 10.

[0026] In addition, the oil-cooled compressor 1 is formed with an intake system that introduces air, which is the gas to be compressed, into the intake port of the compressor main body 10 via an air filter 14 and an intake valve 15, and a compressed gas supply system is formed in which the compressed gas after gas-liquid separation (primary separation) in the receiver tank 11 is further passed through a separator (not shown) to remove any remaining lubricating oil in the compressed gas, and the compressed gas is then introduced into the consumption side to which an air work machine, etc. (not shown) is connected via supply piping 45 equipped with an aftercooler 16, etc. These components are housed in a soundproof box and packaged together with a driving source 17 such as a motor or engine that drives the compressor main body 10 (a motor in the example shown).

[0027] Furthermore, as in a conventional oil-cooled compressor, the bottom of the oil cooler 12 may be positioned higher than the upper limit of the oil level in the receiver tank 11, and a cooler side oil drain means 18 may be provided which is equipped with a cooler oil drain port 18a provided at the bottom of the oil cooler 12 in addition to the lubricating oil inlet 12a and outlet 12b provided in the oil cooler 12, and a cooler drain valve 18b below the cooler oil drain port 18a for opening and closing the cooler oil drain port 18a, so that the secondary side of the cooler drain valve 18b provided in the cooler side oil drain means 18 is connected to the space within the receiver tank 11 (see Figure 1).

[0028] The basic configuration of such an oil-cooled compressor 1 is the same as that of known oil-cooled compressors, and it is also possible to replace this configuration with various known configurations of oil-cooled compressors.

[0029] In the oil-cooled compressor 1 of the present invention having the components described above, the oil cooler 12 is installed above the oil filter 20, as shown in Fig. 2. In this embodiment, as shown in Fig. 2, the bottom of the oil cooler 12 is arranged higher than the upper limit of the oil level in the receiver tank 11, but the present invention is not limited to this.

[0030] 3(b), the oil filter 20 includes a cylindrical casing 21 with an open bottom, a filter element (filter paper) 22 arranged inside the casing 21, and an end plate 23 that closes the bottom opening of the casing 21. The end plate 23 also has a lubricating oil outlet 23b in the center and multiple inlets 23a formed on the outside of the outlet 23b.

[0031] The oil filter 20 is attached to a filter mounting fixture 30. As shown in Fig. 3(b), the filter mounting fixture 30 includes a main body 31 connected to the pipes 43 and 44 (only the connecting portions are shown in Fig. 3), the oil filter 20 is detachably installed on the top surface of the main body, and an inlet passage 33 for introducing lubricating oil into the oil filter 20 and an outlet passage 34 for discharging the lubricating oil filtered by the oil filter 20 are formed inside the main body 31.

[0032] In detail, the inside of the main body 31 of the filter mounting fixture 30 has a cylindrical portion 34a that is integrally formed so as to penetrate vertically through the central interior of the main body 31 and protrude upward from the top surface of the main body, and the cylindrical portion 34a is connected to the outlet 23b by threading an external thread formed on the outer periphery of the upper portion of the cylindrical portion 34a into an internal thread formed on the outlet 23b of the oil filter 20, for example, and is connected to the piping 44 at the lower portion to form the outlet path 34. Furthermore, the inside of the main body 31 of the filter mounting fixture 30 forms the inflow path 33 on the outside of the cylindrical portion 34a that is connected to the piping 43 at the side of the main body and that is connected to the inflow path 23a of the oil filter 20 on the top surface of the main body 31 (see FIG. 3(b)).

[0033] It should be noted that the oil filter 20 and filter mounting fixture 30 described above are merely examples, and in the present invention, they can be replaced with other known oil filters 20 and filter mounting fixtures 30. For example, in the above example, the oil filter 20 is mounted above the filter mounting fixture 30 in a vertical position, but it may also be mounted below the filter mounting fixture 30, or the oil filter 20 may be mounted horizontally on the filter mounting fixture 30. Furthermore, the oil filter 20 may be designed to be connected directly to the pipes 43 and 44 without using the filter mounting fixture 30 described above.

[0034] The discharge structure for residual lubricating oil on the primary side of the oil filter in the oil-cooled compressor of the present invention includes an oil drain passage 50 that branches off from the lower end of the primary flow passage of the oil filter 20 and drains the lubricating oil on the primary side of the oil filter 20. In this embodiment, the oil filter 20 is attached to the filter mounting fixture 30 and connected to the piping 43 via the filter mounting fixture 30, so that the primary flow passage of the oil filter 20 is formed by the piping 43 and the filter mounting fixture 30 (inlet passage 33). As shown in Figures 2 and 3, the oil drain passage 50 is provided, branching off from a nipple elbow 43a that is part of the piping 43 and located at the lower end of the primary flow passage. In this embodiment, the oil drain passage 50 is connected to a receiver tank 11 that is located below the oil filter 20 and the nipple elbow 43a (the lower end of the primary flow passage of the oil filter 20) (see Figure 2).

[0035] In this embodiment, a circular opening 43b is provided at the bottom of the nipple elbow 43a, and a circular opening is also provided on the side wall of the receiver tank 11, and the female threads formed on the inner circumference of each opening can be screwed into the male threads on both ends of the oil drain flow path 50 (piping) to enable installation, but the method of providing the oil drain flow path 50 between the nipple elbow 43a and the receiver tank 11 is not limited to this, and other known methods may also be used.

[0036] 2, the oil drain passage 50 is provided with an opening / closing means (valve) 51 for opening and closing the oil drain passage 50. The opening / closing means 51 can be opened or closed manually or electrically. In the case of an electrically operated opening / closing means, the opening / closing means 51 may be operated by a switch provided on a control panel, for example, or it may be automated by interlocking with the start switch of the compressor main body 10. In this case, the opening / closing means 51 can be closed when the compressor main body 10 is operating and opened when the compressor main body is stopped (the opening / closing means 51 is a normally open solenoid valve), so that the lubricating oil in the piping 43 can be communicated with the receiver tank every time the compressor is stopped. Interlocking the opening / closing means 51 as described above eliminates the need to open or close the opening / closing means 51 and prevents forgetting to open or close the opening / closing means 51.

[0037] In the present embodiment configured as described above, the valve 51 is normally closed, and the lubricating oil in the piping 43 (the primary side of the oil filter 20) passes through the inlet passage 33 of the filter mounting fixture 30, flows into the oil filter 20 from the inlet 23a, passes from the outside to the inside of the filter element 22 and is filtered, and then flows out from the outlet 23b to the piping 44 via the outlet passage 34 of the filter mounting fixture 30, so that the oil can be supplied to the compressor main body 10, as shown in Figure 4.

[0038] On the other hand, when changing the lubricating oil, by opening the valve 51, the lubricating oil in the piping 43 flows from the opening 43b of the nipple elbow 43a through the oil drain passage 50 and into the receiver tank 11, avoiding the oil filter 20, so that the lubricating oil in the piping 43 can be drained into the receiver tank 11 without removing the oil filter 20. In this embodiment, the upper limit oil level position of the receiver tank 11 is set below the nipple elbow 43a (the lower end of the primary-side passage), so that the lubricating oil can be drained into the receiver tank 11 without an external force such as a pump, but the present invention is not limited to this.

[0039] Furthermore, even when replacing the oil filter 20, by opening the valve 51, the lubricating oil flowing from the piping 43 (the primary side of the oil filter 20) can be discharged into the receiver tank 11, avoiding the oil filter 20, so that even if the oil filter 20 is removed, the residual lubricating oil in the piping 43 (the primary side of the oil filter 20) will not overflow from the filter mounting fixture 30.

[0040] The lubricating oil accumulated in the receiver tank 11 can be discharged from a tank oil drain port 11b provided at the bottom. As in conventional oil-cooled compressors, a tank oil drain pipe 11c may be connected below the tank oil drain port 11b, and a tank oil drain port opening / closing means 11d constituted by an opening / closing valve may be provided at the lower end of the tank oil drain pipe 11c, thereby forming tank-side oil draining means 11a, so that the tank oil drain port 11b of the receiver tank 11 can be opened and closed very easily by opening and closing the valve that is the tank oil drain port opening / closing means 11d, without attaching or detaching a drain bolt (see FIG. 1).

[0041] Next, a second embodiment of the present invention will be described.

[0042] In the following, the present embodiment will be described focusing on the differences from the first embodiment, and the description of the similar parts will be omitted. Furthermore, the parts corresponding to the first embodiment will be described with the same reference numerals.

[0043] The discharge structure for residual lubricating oil on the primary side of the oil filter in the oil-cooled compressor of the present invention is provided with an oil drain passage 50 that branches off from the lower end of the primary side passage of the oil filter 20 and drains the lubricating oil on the primary side of the oil filter. In this embodiment, as in the first embodiment, the oil filter 20 is connected to the piping 43 via the filter mounting fixture 30, and the primary side passage of the oil filter 20 is formed by the piping 43 and the filter mounting fixture 30 (inlet passage 33), and a drain oil passage 50 is provided that branches off from the filter mounting fixture 30 located at the lower end of the primary side passage of the oil filter 20, similar to the nipple elbow 43a.

[0044] As shown in Figure 5, an opening 35 communicating with the inlet passage 33 is provided at the bottom of the filter mounting fixture 30, and a female thread is formed inside the opening 35 to allow the oil drain passage 50 to be attached.

[0045] In the present embodiment configured as described above, the valve 51 is normally closed, so that the lubricating oil in the piping 43 (the primary side of the oil filter 20) passes through the inlet passage 33 of the filter mounting fixture 30, flows into the oil filter 20 from the inlet 23a, passes from the outside to the inside of the filter element 22 and is filtered, and then flows out from the outlet 23b to the piping 44 via the outlet passage 34 of the filter mounting fixture 30, so that the oil can be supplied to the compressor main body 10.

[0046] On the other hand, when changing the lubricating oil, by opening the valve 51, the lubricating oil in the piping 43 flows from the opening 35 of the filter mounting fixture 30 through the oil drain passage 50, avoiding the oil filter 20 and into the receiver tank 11, so that the lubricating oil in the piping 43 can be drained into the receiver tank 11 without removing the oil filter 20.

[0047] Similarly, when replacing the oil filter 20, by opening the valve 51, the lubricating oil flowing from the piping 43 can be discharged into the receiver tank 11, bypassing the oil filter 20, so that even if the oil filter 20 is removed, the residual lubricating oil in the piping 43 (primary side of the oil filter) will not overflow from the filter mounting fixture 30.

[0048] Next, a third embodiment of the present invention will be described.

[0049] In the following, the present embodiment will be described focusing on the differences from the first embodiment, and the description of the similar parts will be omitted. Furthermore, the parts corresponding to the first embodiment will be described using the same reference numerals.

[0050] In this embodiment, as shown in FIG. 6, the oil drain passage 50 is designed to lead to the outside of the aircraft instead of the receiver tank 11.

[0051] In this embodiment, the primary side of the oil drain passage 50 is connected to the bottom of the nipple elbow 43a (same as in embodiment 1 above), but this is not limited to this as long as it is the lower end of the primary side of the oil filter 20, and it may, for example, be connected to the bottom of the filter mounting fixture 30 (same as in embodiment 2 above). [Explanation of symbols]

[0052] 1 Oil-cooled compressor 10 Compressor body 11 Receiver tank 11a Tank side oil drainage means 11b Tank oil drain port 11c Tank oil drain piping 11d Tank oil drain opening / closing means 12 Oil cooler 12a Entrance 12b exit 14 Air filter 15 Intake valve 16 Aftercooler 17 Power Source 18 Cooler side oil drainage means 18a Cooler oil drain port 18b Cooler drain valve 20 Oil filter 21 Casing 22 Filter element (filter paper) 23 End plate 23a Inlet 23b Outlet 30 Filter mounting fixture 31 Main Unit 33 Inflow channel 34 Outflow channel 34a Cylindrical part 35 Aperture 41 Piping (between compressor body 10 and receiver tank 11) 42 Piping (between receiver tank 11 and oil cooler 12) 43 Piping (between oil cooler 12 and oil filter 20) 43a nipple elbow 43b opening 44 Piping (between oil filter 20 and compressor body 10) 45 Supply piping 50 Oil drain flow path 51 Valve (opening and closing means) 70 Oil-cooled compressor 71 Compressor body 72 Receiver Tank 73 Oil cooler 73a entrance 73b exit 74 Oil filter 76 Piping (between compressor body 71 and receiver tank 72) 77 Piping (between receiver tank 72 and oil cooler 73) 78 Piping (between oil cooler 73 and oil filter 74) 79 Piping (between oil filter 74 and compressor body 71) 81 Air Filter 82 Intake valve 83 Aftercooler 84 Supply piping 85 Power Source 90 Tank side oil drainage means 91 Tank oil drain port 92 Tank oil drain piping 93 Tank oil drain opening and closing means 94 Oil outlet 95 Cooler side oil drainage means 96 Cooler oil drain port 97 Cooler drain valve

Claims

1. An oil-cooled compressor comprising: a compressor body that discharges compressed gas together with lubricating oil supplied into an operating space; a receiver tank that introduces the compressed gas discharged from the compressor body and separates it into gas and liquid; and an oil cooler that cools the lubricating oil separated in the receiver tank, in which a lubricating oil circulation system is formed in which the lubricating oil cooled in the oil cooler is supplied again to the compressor body via an oil filter, and the oil cooler is located above the oil filter, The oil filter is then cooled to room temperature and the oil temperature is reduced to 100°C. This reduces the amount of oil that is used for the oil cooler.

2. The oil filter is then placed in a position above the receiver tank, and the oil cooler is then placed in a position above the receiver tank. This allows the oil to flow through the receiver tank and into the oil cooler.

3. 2. The structure for discharging residual lubricating oil on the primary side of an oil filter in an oil-cooled compressor according to claim 1, wherein the oil discharge passage is configured to lead to the outside of the compressor.

4. The oil filter is attached to a filter mounting fixture, and the oil drain passage is formed to branch off from the filter mounting fixture located at the lower end of the primary flow passage of the oil filter.

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