Leakage oil recovery mechanism for shaft seal part, abnormality determination method for leakage oil recovery mechanism, and operation control method for work machine

Abstract

To provide a leakage oil recovery mechanism capable of efficiently collecting leakage oil from a shaft seal device and easily grasping abnormality occurrence in such a case.SOLUTION: A shaft seal device 155 is provided, on a side of a prime mover 30, with a lubrication oil collection space 21 and a recovery passage 22 communicating therewith, and further provided, on the side of the prime mover 30, with a screw seal 23 generating an air flow from the side of the prime mover 30 toward the lubrication oil collecting space 21, so that the inside of the lubrication oil collection space 21 can be pressurized. Consequently, lubrication oil collected in the lubrication oil collection space 21 is pressed out to a side of the recovery passage 22 to be efficiently recovered, and the pressure in the lubrication oil collection space 21 rises if a defect in recovery of the lubrication oil is caused owing to clogging of the recovery passage 22 etc., thereby capable of determining abnormality occurring on detecting the pressure in the lubrication oil collection space 21 rising to a predetermined threshold or larger indicative of abnormality occurrence.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a working machine equipped with a working machine main body such as a compressor, generator, pump, etc., and a prime mover such as a motor or engine that drives the working machine main body, and relates to an oil leakage recovery mechanism that recovers lubricating oil (oil leakage) that has leaked from a shaft seal formed by sealing the gap between the inner circumference of a shaft hole that penetrates the casing wall surface between the working machine main body and the prime mover and the outer circumference of a rotating shaft inserted into the shaft hole with a shaft seal device, a method for determining abnormalities in the oil leakage recovery mechanism, and a method for controlling the operation of the working machine based on the results of the abnormality determination. [Background technology]

[0002] In work machines such as engine-driven compressors and motor-driven compressors, in which the compressor body (work machine body) is driven by a prime mover such as an engine or motor, a rotating shaft is provided inside the casing of the work machine body, passing through the casing and protruding toward the prime mover.This rotating shaft is formed integrally with the output shaft of the prime mover, or is connected via a coupling or power transmission means, making it possible for the work machine body to be driven by the prime mover.

[0003] In order to provide a rotating shaft that penetrates the wall of the casing and protrudes toward the prime mover in this manner, a shaft hole is provided that penetrates the wall of the casing located between the work machine body and the prime mover, and a bearing is accommodated in this shaft hole, with the rotating shaft rotatably supported by the bearing.

[0004] An oil supply passage for supplying lubricating oil to the bearings that support the rotating shaft is provided, for example, within the thickness of the casing at the position described above, and lubricating oil from the oil supply source is supplied to the bearings through this oil supply passage.

[0005] As described above, if lubricating oil is supplied to a bearing installed in a shaft hole, which is a through hole, the supplied lubricating oil will lubricate the bearing and then leak out into the engine side through the gap between the outer periphery of the rotating shaft and the inner periphery of the shaft hole.

[0006] Therefore, the shaft hole into which the rotating shaft that penetrates the wall of the casing is inserted is sealed by a shaft sealing device consisting of an oil seal or mechanical seal on the engine side of the bearing, preventing the lubricating oil supplied to the bearing from leaking to the engine side.

[0007] Furthermore, the shaft seal section sealed by the shaft seal device is provided with an oil leakage recovery mechanism for recovering leaked lubricating oil and returning it to the lubricating oil lubrication system, etc., to prevent the leaked lubricating oil (leakage oil) from reaching the engine side even if the lubricating oil passes through the shaft seal device and leaks to the engine side.

[0008] As such an oil leakage recovery mechanism, Patent Document 1, cited below, describes a configuration in which, as shown in Figure 6, a shaft seal device 255 is provided on the prime mover (motor) 230 side of a bearing 251 as a mechanism for recovering oil leakage from the shaft seal portion of a motor-driven, oil-cooled screw compressor, and a lubricant oil collection space 221 is provided at the outer periphery of the rotating shaft on the motor 230 side of the shaft seal device 255 to collect the lubricant oil that has passed through the shaft seal device 255, and a recovery flow path 222 is provided at the lower end side of this lubricant oil collection space 221, one end 222a of which is connected, and the other end 222b of this recovery flow path 222 is connected to a storage container 260 that is open to the atmosphere (Figure 1 of Patent Document 1).

[0009] Patent Document 1 also describes a configuration in which the other end 222b of the recovery passage 222 is connected to the intake passage of the compressor main body 210 on the secondary side of the intake control valve (Figures 6 and 7 of Patent Document 1). [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2023-67189 Summary of the Invention [Problem to be solved by the invention]

[0011] In the oil leakage recovery mechanism described in Patent Document 1 mentioned above, by providing a shaft seal device 255 on the motor 230 side of bearing 251, not only is the lubricating oil supplied to bearing 251 sealed so as not to leak to the motor 230 side, but even if lubricating oil leaks from shaft seal device 255, the leaked lubricating oil is collected in lubricating oil collection space 221 and recovered via recovery flow path 222, so that the lubricating oil does not reach the motor 230 side beyond lubricating oil collection space 221.

[0012] However, among the configurations of the oil leakage recovery mechanism described in Patent Document 1 mentioned above, in the configuration in which the other end 222b of the recovery flow path 222 is connected to a storage container 260 that is open to the atmosphere (the configuration shown in Figure 6 attached to the present application), the lubricating oil collected in the lubricating oil collection space 221 falls within the recovery flow path 222 by its own weight and is collected in the storage container 260, which results in poor recovery efficiency.Furthermore, in order to collect the lubricating oil by falling by its own weight, it is necessary to position the storage container 260 at a position lower than the lower end position of the lubricating oil collection space 221, which also creates design constraints.

[0013] On the other hand, in the configuration described in Figures 6 and 7 of Patent Document 1 (not shown in the present application), in which the other end 222b of the recovery passage 222 is connected to the intake passage 281 of the compressor main body 210 on the secondary side of the intake control valve 280, during no-load operation with the intake control valve 280 closed, negative pressure is created within the intake passage 281 of the compressor main body 210, and this negative pressure can be used to efficiently recover the lubricating oil collected in the lubricating oil collection space 221.

[0014] However, during load operation with the intake control valve 280 open, no negative pressure is generated in the intake passage 281 of the compressor body 210 that is sufficient to suck in the lubricating oil in the recovery passage 222.Furthermore, since the intake passage 281 of the compressor body 210 is generally located higher than the lower end of the lubricating oil collection space 221, the lubricating oil in the lubricating oil collection space 221 does not flow into the intake passage 281 by natural fall.Therefore, if the compressor body 210 continues to operate under load for a long period of time, the lubricating oil continues to accumulate in the lubricating oil collection space 221 without being recovered, and the lubricating oil that has accumulated beyond the capacity of the lubricating oil collection space 221 will overflow the lubricating oil collection space 221 and flow out to the motor 230 side.

[0015] In order to prevent the lubricating oil in the lubricating oil collection space 221 from leaking to the motor 230 side in this way, it is necessary to periodically forcibly switch the operating state of the compressor main body 210 to no-load operation and recover the lubricating oil before it accumulates in the lubricating oil collection space 221 beyond its capacity. However, since compressed air is not generated during no-load operation, a forced switch to no-load operation creates the problem that air work machines and the like that operate using compressed air supplied from the compressor must also be stopped.

[0016] Therefore, there is a demand for a leaked oil recovery mechanism that can efficiently recover leaked oil collected in the lubricating oil collection space while the work machine body is operating, regardless of the operating state of the work machine.

[0017] Furthermore, in the conventional oil leakage recovery mechanism 220 described above, if a large amount of leaked oil flows into the lubricant oil collection space 221 due to a decrease in performance of the shaft seal device 255 caused by aging, exceeding the collection capacity of the oil leakage recovery mechanism 220, or if the recovery flow path 222 becomes narrow due to clogging, recovery failure will occur in which all of the lubricant oil collected in the lubricant oil collection space 221 cannot be recovered.Furthermore, if the recovery flow path 222 becomes completely blocked due to clogging, recovery failure will occur in which none of the lubricant oil in the lubricant oil collection space 221 can be recovered, and if the accumulated lubricant oil that cannot be recovered exceeds the capacity of the lubricant oil collection space 221, it will flow out to the prime mover (motor) 230 side.

[0018] Furthermore, in a configuration in which the motor-side end 215a of the axial hole 215 is arranged inside the motor housing 231, such as the motor-driven compressor described in Patent Document 1 shown in Figure 6, the lubricating oil that moves beyond the lubricating oil collection space 221 toward the motor 230 leaks into the motor housing 231.

[0019] As a result, even if such a lubricating oil leak occurs, it cannot be confirmed by simply inspecting the outside of the motor housing 231 visually, and if the lubricating oil leak is discovered late, the inside of the motor housing 231 may become contaminated, which may cause the motor 230 to malfunction.

[0020] Therefore, it is desirable to be able to identify the occurrence of such poor oil recovery problems before the lubricating oil leaks into the engine, or at an early stage when it begins to leak into the engine.

[0021] However, among conventional oil leakage recovery mechanisms, there is no mechanism that is capable of detecting an abnormality that causes the aforementioned poor recovery of the lubricating oil collected in the lubricating oil collection space 221, even if such an abnormality occurs.

[0022] Therefore, the present invention has been made to eliminate the drawbacks of the above-mentioned conventional technology, and aims to provide an oil leakage recovery mechanism for the shaft seal section that can efficiently recover lubricating oil that has leaked from the shaft seal device and been collected in the lubricating oil collection space, and that can easily detect any abnormalities that result in poor recovery of the lubricating oil collected in the lubricating oil collection space, a method for determining abnormalities in the oil leakage recovery mechanism, and a method for controlling the operation of a work machine based on the results of the determination. [Means for solving the problem]

[0023] 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 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.

[0024] In order to achieve the above object, the shaft seal leak oil recovery mechanism 20 of the present invention is as follows: In a shaft seal leaked oil recovery mechanism (20), bearings (151, 152) are housed in a shaft hole (15) that penetrates a wall surface of a casing between a work machine body (10) and a prime mover (30) (an end cover (14a) of a casing (14) of a speed increasing device (13) in the embodiment shown in Figs. 1 to 3), and a rotating shaft (131) that connects the work machine body (10) and the prime mover (30) is rotatably supported by the bearings (151, 152), and the shaft seal device (155) is provided on the prime mover (30) side of the bearings (151, 152) to prevent leakage of lubricating oil supplied to the bearings (151, 152), a lubricating oil collecting space (21) is provided on the prime mover (30) side of the shaft seal device (155) to collect lubricating oil that has passed through the shaft seal device (155), and a recovery flow path (22) whose one end (22a) is connected to a lower end of the lubricating oil collecting space (21) to recover the lubricating oil collected in the lubricating oil collecting space (21), A screw seal 23, 23' is provided at a position closer to the motor 30 than the lubricant collecting space 21, and introduces air from the motor 30 side into the lubricant collecting space 21 by rotation of the rotary shaft 131, The lubricant oil collecting space 21 is characterized by the provision of a pressure detection means 27 (such as a pressure switch or pressure sensor) that detects when the pressure in the lubricant oil collecting space 21 rises above a predetermined threshold value TH and outputs a detection signal (claim 1).

[0025] The oil leakage recovery mechanism 20 of the shaft seal section configured as described above may be provided with a control device (electronic control device) 26 that receives the detection signal from the pressure detection means 27 and stops the operation of the prime mover 30 and / or causes the warning notification means 50 to issue a warning (Claim 2).

[0026] The oil leakage recovery mechanism 20 of the shaft seal portion having the above-mentioned configuration is provided with an air discharge flow path 24, one end 24a of which is connected to the lubricating oil collecting space 21 and the other end 24b of which is open to the atmosphere, and an opening / closing valve 25 for opening and closing the air discharge flow path 24, The control device 26 When the detection signal is not received from the pressure detection means 27, the on-off valve 25 is closed, It may be configured such that, upon receiving the detection signal from the pressure detection means 27, the operation of the prime mover 30 is stopped and the on-off valve 25 is opened (claim 3).

[0027] When such an air discharge flow path 24 is provided, the pressure detection means 27 may be configured to detect that the pressure in the lubricant collection space 21 has risen above the threshold value TH based on the pressure in the part of the air discharge flow path 24 that is on the lubricant collection space 21 side (the primary side of the opening / closing valve 25) relative to the opening / closing valve 25.

[0028] The outer diameter of the rotating shaft 131 and the inner diameter of the shaft hole 15 at the portion where the screw seal 23' is formed may be formed in a tapered shape that becomes larger from the motor 30 side toward the lubricant oil collection space 21 side (Claim 4).

[0029] In addition, in a configuration in which the end 15a of the shaft hole 15 on the prime mover 30 side is positioned within the housing 31 of the prime mover 30, an intake chamber 28 isolated from the internal space of the housing 31 may be provided between the outer surface of the rotating shaft 131 on the prime mover 30 side and the inner surface of the shaft hole 15 relative to the screw seal 23, and an intake flow path 71 may be provided (for example, within the thickness of the end cover 14a of the casing 14) whose one end 71a is connected to the intake chamber 28 and whose other end 71b opens outside the housing 31 (claims 5 and 6).

[0030] In addition, the method for determining an abnormality in the oil leakage recovery mechanism of the shaft seal of the present invention is as follows: A method for determining an abnormality in an oil leakage recovery mechanism (20) of a shaft seal portion, the method comprising: accommodating bearings (151, 152) in a shaft hole (15) that penetrates a wall surface of a casing between a work machine body (10) and a prime mover (30); rotatably supporting a rotating shaft (131) that connects the work machine body (10) and the prime mover (30) on the bearings (151, 152); a shaft seal device (155) on the prime mover (30) side of the bearings (151, 152) that prevents leakage of lubricating oil supplied to the bearings (151, 152); a lubricating oil collecting space (21) on the prime mover (30) side of the shaft seal device (155) that collects lubricating oil that has passed through the shaft seal device (155); and a recovery flow path (22) having one end (22a) connected to a lower end of the lubricating oil collecting space (21) that recovers the lubricating oil collected in the lubricating oil collecting space (21), By providing screw seals 23, 23' at a position closer to the motor 30 than the lubricant collecting space 21, which introduce air from the motor 30 side into the lubricant collecting space 21 by the rotation of the rotating shaft 131, the introduction of air into the lubricant collecting space 21 continues while the rotating shaft 131 is rotating, The pressure in the lubricant collecting space 21 is monitored, When the pressure in the lubricating oil collecting space 21 rises to or exceeds a predetermined threshold value TH, it is determined that an abnormality has occurred in the leaked oil recovery mechanism 20 (claim 7).

[0031] Furthermore, the operation control method of the working machine of the present invention includes: A method for controlling the operation of a work machine including: bearings (151, 152) housed in a shaft hole (15) that penetrates the wall of a casing between a work machine body (10) and a prime mover (30); a rotating shaft (131) that connects the work machine body (10) and the prime mover (30) that is rotatably supported by the bearings (151, 152; a shaft seal device (155) on the prime mover (30) side of the bearings (151, 152) that prevents leakage of lubricating oil supplied to the bearings (151, 152); a lubricating oil collecting space (21) on the prime mover (30) side of the shaft seal device (155) that collects lubricating oil that has passed through the shaft seal device (155); and a recovery flow path (22) whose one end (22a) is connected to the lower end of the lubricating oil collecting space (21) that collects the lubricating oil collected in the lubricating oil collecting space (21), By providing screw seals 23, 23' at a position closer to the motor 30 than the lubricant collecting space 21, which introduce air from the motor 30 side into the lubricant collecting space 21 by the rotation of the rotating shaft 131, the introduction of air into the lubricant collecting space 21 continues while the rotating shaft 131 is rotating, The pressure in the lubricant collecting space 21 is monitored, When the pressure in the lubricant collection space 21 rises above a predetermined threshold value TH, the operation of the prime mover 30 is stopped and / or the warning notification means 50 is caused to issue a warning (Claim 8).

[0032] In the operation control method for the work machine having the above configuration, an air release passage having one end connected to the lubricating oil collecting space and the other end open to the atmosphere, and an opening / closing valve for opening and closing the air release passage; When the pressure in the lubricating oil collecting space is less than the threshold value, the on-off valve is closed, When the pressure in the lubricant oil collecting space reaches or exceeds the threshold value, the operation of the prime mover may be stopped and the on-off valve may be opened (claim 9). [Effects of the Invention]

[0033] With the configuration of the present invention described above, the present invention can achieve the following significant effects.

[0034] By providing screw seals 23, 23' on the engine 30 side of the lubricant oil collection space 21 to generate an air flow toward the lubricant oil collection space 21, leaked oil collected in the lubricant oil collection space 21 while the rotating shaft 131 is rotating is pushed back toward the lubricant oil collection space 21 by the screw seals 23, 23', not only preventing the lubricant oil from leaking toward the engine 30 side, but also increasing the pressure within the lubricant oil collection space 21 due to the introduction of the air flow generated by the screw seals 23, 23', allowing the lubricant oil collected in the lubricant oil collection space 21 to be pressurized into the recovery flow path 22, thereby enabling the leaked oil to be recovered efficiently.

[0035] Furthermore, by adopting a configuration in which an air flow generated by the screw seals 23, 23' is introduced into the lubricant collection space 21 to pressurize the lubricant, it is possible to recover the lubricant even when the other end 22b of the recovery flow path 22 is connected to an open-to-air storage container (not shown) located at a position higher than the lower end of the lubricant collection space 21, thereby increasing the degree of freedom in design.

[0036] Furthermore, by making it possible to recover the lubricating oil in the lubricating oil collection space 21 by pressurizing it, if the other end 22b of the recovery flow path 22 is connected to the intake flow path of the oil-cooled screw compressor on the secondary side of the intake control valve, it becomes possible to recover the lubricating oil not only during no-load operation with the intake control valve closed, but also during loaded operation with the intake control valve open.

[0037] As a result, it is no longer necessary to force the compressor to operate at no load periodically, which was necessary with conventional oil leakage recovery mechanisms that recover lubricating oil through the intake passage of the compressor body.

[0038] In addition, by introducing the air flow generated by the screw seals 23, 23' into the lubricant collection space 21, if a large amount of lubricant oil flows into the lubricant collection space 21 from the shaft seal device 155, exceeding the recovery capacity of the leaked oil recovery mechanism 20, resulting in poor recovery in which not all of the lubricant oil in the lubricant collection space 21 is recovered, or if the recovery flow path 22 becomes narrow or blocked due to clogging, resulting in poor recovery in which only a portion of the lubricant oil in the lubricant collection space 21 or none of it can be recovered at all, the pressure in the lubricant collection space 21 will increase compared to when the lubricant oil in the lubricant collection space is being recovered normally.

[0039] Therefore, as an example, by setting a lower limit value of the pressure in the lubricant collection space 21 when such poor recovery of lubricant occurs, or a predetermined lower pressure than the lower limit value as a threshold value TH, and providing a pressure detection means 27 such as a pressure switch or pressure sensor to detect when the pressure in the lubricant collection space 21 reaches or exceeds the threshold value TH and output a detection signal, it becomes possible to early detect and determine the occurrence of abnormalities such as poor recovery of lubricant, or the causes thereof, such as deterioration of the shaft seal device 155 or clogging of the recovery flow path 22.

[0040] Furthermore, based on the detection signal from the pressure detection means 27, the prime mover 30 can be stopped to bring the work machine to an emergency stop, and / or the warning notification means 50 can be made to issue a warning to make the operator aware of the occurrence of an abnormality, thereby not only preventing the leakage of lubricating oil to the prime mover side that would otherwise occur if operation were to continue in an abnormal state, but also enabling the operator to take the necessary measures (such as replacing the shaft seal device or clearing clogging).

[0041] In particular, as shown in Figures 1 to 5, in a configuration in which the work machine main body 10 and the motor 30, which is the prime mover, are separated by a common wall surface (end cover 14a of casing 14), the end 15a of the shaft hole 15 on the motor 30 side is positioned within the motor housing 31, so that lubricating oil that passes through the shaft hole 15 and leaks toward the motor 30 side accumulates within the motor housing 31.

[0042] As a result, it is not possible to determine whether lubricating oil is leaking from the end 15a of the shaft hole 15 simply by observing from the outside of the motor housing 31, and it is extremely useful in a work machine with such a structure to be able to detect early on any abnormalities in poor recovery that can cause lubricating oil to leak to the motor 30 side.

[0043] In a configuration in which an air discharge flow path 24 is provided, one end 24a of which is connected to the lubricating oil collection space 21 and the other end 24b of which is open to the atmosphere, and an on-off valve 25 is provided to open and close the air discharge flow path 24, when the pressure detection means 27 is not outputting a detection signal, the on-off valve 25 is closed and the work machine main body 10 is operated with the air discharge flow path 24 closed, thereby increasing the pressure in the lubricating oil collection space 21 and smoothly recovering leaked oil, and on the other hand, when the prime mover 30 is stopped, the on-off valve 25 is opened to open the air discharge flow path 24, releasing the pressure in the lubricating oil collection space 21 and reducing the pressure in the lubricating oil collection space 21 to atmospheric pressure.

[0044] Since the screw seals 23, 23' provided on the engine 30 side relative to the lubricant collection space 21 are non-contact seals, when the rotation of the rotating shaft 131 stops due to the engine 30 being stopped, the screw seals 23, 23' no longer exert their effect of pushing the lubricant back toward the lubricant collection space 21. However, if the pressure in the lubricant collection space 21 remains high at this time, there is a risk that the lubricant in the lubricant collection space 21 will blow out toward the engine 30 through the gaps that occur in the screw seals 23, 23'.

[0045] In response to this, the pressure in the lubricating oil collecting space 21 is released via the air release passage 24 when the prime mover 30 is stopped, thereby making it possible to prevent the above-mentioned blowing out of the lubricating oil.

[0046] Furthermore, in a configuration in which an air discharge flow path 24 communicating with the lubricant oil collection space 21 is provided, pressure changes within the lubricant oil collection space 21 can be easily detected by detecting pressure changes within the air discharge flow path 24.

[0047] In a configuration in which the outer diameter of the rotating shaft 131 and the inner diameter of the shaft hole at the forming portion of the screw seal 23' are formed in a tapered shape that becomes larger from the motor 30 side toward the lubricant collection space 21 side, not only does the increased amount of air introduced into the lubricant collection space 21 increase the force pushing the lubricant back toward the lubricant collection space 21 and improve sealing performance, but the increased amount of air introduced into the lubricant collection space 21 also enhances the effect of pressurizing the lubricant to the recovery flow path 22.

[0048] Furthermore, in a configuration in which the end 15a of the shaft hole 15 on the prime mover 30 side is positioned within the housing (motor housing) 31 of the prime mover 30, an intake chamber 28 isolated from the internal space of the housing 31 is provided between the rotating shaft 131 on the prime mover 30 side and the inner wall of the shaft hole 15 for the screw seal 23, and an intake flow path 71 is provided whose one end 71a is connected to the intake chamber 28 and whose other end 71b opens outside the housing 31, thereby eliminating the need to provide an intake hole 70 in the housing 31 for introducing air into the screw seal 23 and improving the dustproof performance of the prime mover 30 (prime mover housing 31). [Brief explanation of the drawings]

[0049] [Figure 1] 1 is a partially cross-sectional plan view of a motor-driven oil-free screw compressor equipped with an oil leakage recovery mechanism for a shaft seal according to the present invention. [Figure 2] 1 is a cross-sectional side view of a motor-driven oil-free screw compressor equipped with an oil leakage recovery mechanism for a shaft seal according to the present invention. [Figure 3] 1 is a partially cross-sectional side view of a motor-driven oil-free screw compressor equipped with an oil leakage recovery mechanism for a shaft seal according to the present invention. [Figure 4] 10 is a partially cross-sectional side view of a motor-driven oil-free screw compressor equipped with a modified shaft seal oil recovery mechanism of the present invention. FIG. [Figure 5] FIG. 10 is a partial cross-sectional side view of a motor-driven oil-free screw compressor equipped with an oil leakage recovery mechanism for a shaft seal portion according to another modified example of the present invention. [Figure 6]FIG. 1 is an explanatory diagram of a conventional oil leakage recovery mechanism for a shaft seal (corresponding to FIG. 1 of Patent Document 1). DETAILED DESCRIPTION OF THE INVENTION

[0050] Hereinafter, a working machine equipped with a mechanism for recovering oil leaked from a shaft seal according to the present invention will be described with reference to the accompanying drawings.

[0051] In the following explanation, we will explain the configuration in which the oil leakage recovery mechanism of the present invention is installed in the shaft seal section of a motor-driven oil-free screw compressor, but the working machines to which the oil leakage recovery mechanism of the present invention can be applied are not limited to motor-driven working machines, but can also be applied to engine-driven working machines, and as working machines, it can be applied to various working machines that are driven by prime movers such as engines and motors, including generators and pumps, in addition to compressors.

[0052] [Overall configuration of motor-driven oil-free screw compressor] 1 and 2 show the overall configuration of a motor-driven oil-free screw compressor 1 equipped with a leaked oil recovery mechanism 20 of the present invention.

[0053] This oil-free screw compressor 1 includes a compressor body 10 that compresses the gas to be compressed without supplying oil into the compression working space, and a motor 30 that serves as a prime mover for driving this compressor body 10.

[0054] Of these, the compressor body 10 is composed of a low-pressure stage compressor body 11 that draws in air as the gas to be compressed and performs primary compression, as shown in Figure 1, a high-pressure stage compressor body 12 that performs secondary compression as the gas to be compressed the compressed air generated by the primary compression by this low-pressure stage compressor body 11, and a speed increase device 13 that increases the rotation speed of the low-pressure stage compressor body 11 and the high-pressure stage compressor body 12.

[0055] This speed increasing device 13 is equipped with a rotating shaft 131 that is connected to and rotated by a motor 30 described later, a drive gear 132 attached to the rotating shaft 131, and two driven gears 133, 134 that are smaller in diameter than the drive gear 132 and rotate in mesh with the drive gear 132.One of the driven gears 133, 134, 133, is attached to the input shaft 11a of the low-pressure stage compressor body 11, and the other, 134, is attached to the input shaft 12a of the high-pressure stage compressor body 12.By rotating the rotating shaft 131 and drive gear 132 of the speed increasing device 13 using the motor 30, both the low-pressure stage compressor body 11 and the high-pressure stage compressor body 12 can be rotated at an increased speed via the driven gears 133, 134.

[0056] The casing 14 of the speed increasing device 13 has a shaft hole 15 that penetrates the end cover 14a of the casing 14, and the rotating shaft 131 of the speed increasing device 13 is rotatably supported within this shaft hole 15 via bearings 151 and 152.

[0057] As shown in Figures 1 to 3, in this embodiment, the rotating shaft 131 of the speed increaser 13 is formed integrally with the rotor shaft of the motor 30, and this rotating shaft 131 passes through the end cover 14a of the casing 14 of the speed increaser 13 and protrudes into the housing 31 of the motor 30, becoming the rotor shaft of the motor 30 within the motor housing 31.

[0058] The end cover 14a of the casing 14 of the speed increasing device 13 has a cylindrical boss 16 concentric with the aforementioned shaft hole 15 on the surface facing the motor 30, and by attaching the cylindrical main body part of the motor housing 31 to this boss 16, the end cover of the motor housing 31 on the speed increasing device 13 side is formed by the aforementioned boss 16 and the part of the end cover 14a of the casing 14 of the speed increasing device 13 located on the inner circumference of the boss 16, and in the illustrated embodiment, the casing 14 of the speed increasing device 13 and the motor housing 31 have a structure in which they share part of their construction.

[0059] In addition, the boss 16 mentioned above has an intake hole 70 that penetrates the thickness of the boss 16, and is configured so that outside air can be taken into the motor housing 31 through this intake hole 70.

[0060] [Shaft seal] As shown in Figure 3, the shaft hole 15 provided in the end cover 14a of the casing 14 is provided with bearings 151 and 152 that rotatably support the aforementioned rotating shaft 131, and an oil supply space 153 is provided between the inner circumference of the shaft hole 15 located on the prime mover (motor) 30 side of the bearings 151 and 152 and the outer circumference of the rotating shaft 131 for introducing lubricating oil to be supplied to the bearings 151 and 152, and an oil supply passage 154 is connected to this oil supply space 153 for introducing lubricating oil from an oil supply source not shown.

[0061] Furthermore, a shaft sealing device 155 consisting of a mechanical seal, an oil seal, etc. is provided on the motor 30 side of this oil supply space 153 to seal the gap between the outer periphery of the rotating shaft 131 and the inner periphery of the shaft hole 15, thereby preventing the lubricating oil introduced into the oil supply space 153 from leaking toward the motor 30 side.

[0062] [Oil spill recovery mechanism] (1) Lubricant collection space and recovery flow path Even when a shaft seal device 155 consisting of the aforementioned mechanical seal, oil seal, etc. is provided, the lubricating oil supplied to the oil supply space 153 may leak past the shaft seal device 155 and toward the motor 30, so an oil leakage recovery mechanism 20 is provided in the part where such a shaft seal is performed (shaft seal section) to recover the lubricating oil (leakage oil) that has leaked through the shaft seal device 155.

[0063] This oil leakage recovery mechanism 20 has in common with the configuration of the conventional oil leakage recovery mechanism (Patent Document 1) described with reference to Figure 6 in that it is equipped with a lubricating oil collection space 21 provided on the motor 30 side of the aforementioned shaft seal device 155 and a recovery flow path 22 whose one end 22a is connected to the lower end of this lubricating oil collection space 21.

[0064] In this embodiment, in which the working machine main body (compressor main body) 10 is an oil-free screw compressor, the other end 22b (see Figure 2) of the recovery flow path 22 is connected to an oil reservoir 19 formed in the casing 14 of the speed increasing device 13, which is open to the atmosphere via an oil mist filter 18 (see Figure 1) (see Figure 2).However, if, instead of this configuration, the working machine main body 10 is an oil-cooled screw compressor, although not shown in the figure, the other end 22b of the recovery flow path 22 may be connected to the suction flow path of the oil-cooled screw compressor main body on the secondary side of the intake control valve.

[0065] In this way, if the other end 22b of the recovery flow path 22 is connected to the suction flow path of the oil-cooled screw compressor main body on the secondary side of the intake control valve, the compressed air that was being compressed when the oil-cooled screw compressor main body is stopped will flow back to the suction flow path side, causing the pressure in the suction flow path to rise, and a backflow of lubricating oil and compressed air may occur from the other end 22b of the recovery flow path 22 toward the lubricating oil collection space 21.Therefore, in order to prevent such backflow from occurring, the other end 22b of the recovery flow path 22 is connected to the suction flow path of the oil-cooled screw compressor main body via a check valve.

[0066] (2) Thread seal In addition to the configuration of the conventional oil leakage recovery mechanism described with reference to Figure 6, the oil leakage recovery mechanism 20 of the present invention further includes a screw seal 23 on the motor 30 side of the lubricant oil collection space 21, and this screw seal 23 generates an air flow from the motor 30 side toward the lubricant oil collection space 21 when the rotating shaft 131 rotates.

[0067] In this way, by introducing the air flow generated by the screw seal 23 into the lubricant collection space 21, the pressure within the lubricant collection space 21 increases, and this pressure is used to pressurize the lubricant collected within the lubricant collection space 21 into the oil reservoir 19 of the speed increase device 13 via the recovery flow path 22, thereby enabling smooth and efficient recovery of the lubricant.

[0068] In the embodiment shown in Figure 3, the outer diameter of the rotating shaft 131 and the inner diameter of the shaft hole 15 at the portion where the screw seal 23 is formed are both shaped to have a constant diameter in the longitudinal direction of the rotating shaft 131, but instead of this configuration, as shown in Figure 4, the outer diameter of the rotating shaft 131 and the inner diameter of the shaft hole 15 at the portion where the screw seal 23' is formed may be formed in a tapered shape that becomes larger from the motor 30 side toward the lubricant collection space 21 side.

[0069] By forming it in such a tapered shape, a difference in peripheral speed and pressure occurs between the part of the screw seal 23' on the motor 30 side and the part on the lubricant collection space 21 side, increasing the force with which the screw seal 23' draws in air and increasing the amount of air introduced into the lubricant collection space 21. Not only is the effect of pushing the lubricant back toward the lubricant collection space 21 strengthened, but the increased amount of air introduced into the lubricant collection space 21 also enhances the effect of pressurizing the lubricant to the recovery flow path 22, making it possible to recover the lubricant more efficiently.

[0070] (3) Air release flow path and electromagnetic on-off valve In the oil leakage recovery mechanism 20 of the present invention, not only is the lubricating oil collection space 21 connected to the recovery flow path 22, but one end 24a of the air discharge flow path 24 is also connected to the upper end side of the lubricating oil collection space 21.

[0071] The other end 24b of this air discharge flow path 24 is open to the atmosphere, and an opening / closing valve 25 such as an electromagnetic opening / closing valve is provided in the air discharge flow path 24 to open and close it.When the opening / closing valve 25 is opened, the lubricating oil collection space 21 is opened to the atmosphere via the air discharge flow path 24, and when the opening / closing valve 25 is closed, the opening of the lubricating oil collection space 21 to the atmosphere via the air discharge flow path 24 can be terminated.

[0072] In this way, the oil leakage recovery mechanism 20 of the present invention is provided with, in addition to the screw seals 23, 23' mentioned above, an air discharge flow path 24 and an on-off valve 25 for opening and closing the air discharge flow path 24. Therefore, when the rotating shaft 131 is rotated with the air discharge flow path 24 closed by the on-off valve 25, the air inside the motor housing 31 is introduced into the lubricant oil collection space 21 by the screw seals 23, 23', thereby increasing the pressure inside the lubricant oil collection space 21. As a result, the lubricant oil that has been collected in the lubricant oil collection space 21 and accumulated at the bottom of the space can be smoothly recovered by being pressure-fed into the oil reservoir 19 of the speed increaser 13 via the recovery flow path 22.

[0073] On the other hand, when the motor 30 is stopped and the rotation of the rotating shaft 131 is stopped, the on-off valve 25 is opened to release the pressure in the lubricant collection space 21. Although the sealing performance of the screw seals 23, 23', which are non-contact seals, is reduced when the rotation of the rotating shaft 131 is stopped, the pressure in the lubricant collection space 21 is reduced to atmospheric pressure, so the lubricant in the lubricant collection space 21 is prevented from blowing out toward the motor 30 through the gaps that occur in the screw seals 23, 23'.

[0074] (4) Pressure detection means The oil leakage recovery mechanism 20 of the present invention is further provided with a pressure detection means 27 such as a pressure switch or pressure sensor that outputs a detection signal when the pressure in the lubricant collection space 21 exceeds a predetermined threshold value TH, and in this embodiment, the pressure in the lubricant collection space 21 can be detected by providing a pressure detection means 27 that detects the pressure in the air discharge flow path 24 on the lubricant collection space 21 side (primary side of the opening / closing valve 25) of the aforementioned opening / closing valve 25.

[0075] In the oil leakage recovery mechanism 20 of the present invention, when the rotating shaft 131 is rotated with the air discharge passage 24 closed by the on-off valve 25, the air flow generated by the screw seals 23, 23' is introduced, causing the pressure in the lubricant collection space 21 to increase.However, when the lubricant (leaked oil) in the lubricant collection space 21 is being recovered normally by the oil leakage recovery mechanism 20, such as when there is no lubricant leakage from the shaft seal device 155, or when there is leakage but the amount is small and within the recovery capacity of the oil leakage recovery mechanism 20, the air introduced into the lubricant collection space 21 is discharged together with the lubricant via the recovery passage 22 to the oil reservoir 19 of the speed increaser 13, and no excessive pressure increase occurs in the lubricant collection space 21.

[0076] However, if the amount of oil leakage increases due to a decrease in the sealing ability of the shaft seal device 155 due to aging or other reasons, and a large amount of lubricating oil is collected in the lubricating oil collection space 21, exceeding the collection capacity of the leaked oil recovery mechanism 20, poor recovery of the lubricating oil will occur, with only a portion of the lubricating oil collected in the lubricating oil collection space 21 being able to be recovered, and the pressure in the lubricating oil collection space 21 will increase because the discharge of air from the lubricating oil collection space 21 through the recovery flow path 22 will be restricted.

[0077] Furthermore, if the recovery flow path 22 becomes narrow or blocked due to clogging, the amount of lubricating oil recovered from the lubricating oil collection space 21 will decrease, or recovery will be poor and the recovery of lubricating oil will stop.As a result, the amount of air discharged from the lubricating oil collection space 21 will decrease, or the discharge of air will stop altogether, and in this case too the pressure within the lubricating oil collection space 21 will increase.

[0078] In this way, in the oil leakage recovery mechanism 20 of the present invention, by adopting a configuration in which screw seals 23, 23' are provided on the motor 30 side of the lubricant oil collection space 21, not only is it possible to efficiently recover the lubricant oil collected in the lubricant oil collection space 21 by pressurizing it, but also, if a recovery failure occurs in the oil leakage recovery mechanism 20 in which the lubricant oil collected in the lubricant oil collection space 21 cannot be recovered normally, the pressure in the lubricant oil collection space 21 will rise compared to when the lubricant oil is being recovered normally, and by monitoring the pressure in the lubricant oil collection space 21, it is possible to determine whether such an abnormal recovery failure has occurred.

[0079] Taking note of the above point, the oil leakage recovery mechanism 20 of the shaft seal portion of the present invention is provided with a pressure detection means 27 for detecting the pressure in the air discharge flow path 24 on the lubricating oil collection space 21 side (the primary side of the opening / closing valve 25) of the aforementioned opening / closing valve 25, and this pressure detection means 27 is configured to detect when the pressure in the air discharge flow path 24, and therefore the pressure in the lubricating oil collection space 21, has reached or exceeded a predetermined threshold value TH, and to output a detection signal.

[0080] As an example, the aforementioned threshold value TH may be determined by measuring or calculating the pressure in the air discharge flow path 24 (lubricant collection space 21) when poor recovery of lubricant in the lubricant collection space 21 occurs, such as when lubricant leaks from the shaft seal device 155 in an amount that exceeds the recovery capacity of the leaked oil recovery mechanism 20, or when the recovery flow path 22 is clogged, and the minimum pressure among these, or a pressure that is lower than the minimum pressure by a predetermined margin, may be set as the aforementioned threshold value TH.

[0081] Alternatively, the pressure in the air discharge flow path 24 (lubricant collection space 21) when the leaked oil is being normally collected by the leaked oil collection mechanism 20 can be measured or calculated, and the maximum value of the obtained value, or a pressure that is higher than the maximum value by a predetermined margin, can be set as the threshold value TH.

[0082] By setting the threshold value TH to such a value, it becomes possible to detect poor recovery of lubricating oil in the leaked oil recovery mechanism 20, and therefore leakage of lubricating oil into the motor casing 31, before it occurs or at an early stage of occurrence.

[0083] (5) Warning notification means The motor-driven oil-free screw compressor 1 equipped with the oil leakage recovery mechanism 20 of the present invention can be provided with a warning notification means 50 as shown in FIG.

[0084] In the example shown in Figure 3, a warning light 51 and an alarm 52 that issues a warning sound are provided as the warning notification means 50, but the warning notification means 50 may also be configured to display a warning using an LCD panel or the like provided on the control panel of the oil-free screw compressor, and various known means can be used as the warning notification means.

[0085] (6) Control device As shown in Figure 3, the oil leakage recovery mechanism 20 of the present invention is further provided with a control device 26 consisting of an electronic control device such as a microcontroller that controls the operation of the aforementioned opening / closing valve 25, the motor 30 which is the prime mover, and the warning notification means 50 such as a warning light 51 and an alarm 52 based on a detection signal from the pressure detection means 27.

[0086] When this control device 26 does not receive a detection signal from the aforementioned pressure detection means 27, i.e., when the pressure in the air discharge flow path 24 (lubricant collection space 21) is below the threshold value TH, it enables current to be applied to the motor 30, closes the opening / closing valve 25, and keeps the warning notification means 50, such as the warning light 51 and alarm 52, in a stopped state.

[0087] As a result, the rotating shaft 131 rotates with the air discharge flow path 24 closed by closing the on-off valve 25, and the lubricating oil collected in the lubricating oil collection space 21 by the introduction of the air flow generated by the screw seals 23, 23' is pushed out into the oil reservoir 19 of the speed increaser 13 through the recovery flow path 22 and recovered.

[0088] On the other hand, when the control device 26 receives a detection signal from the pressure detection means 27 that detects that the pressure in the air discharge flow path 24 (lubricant collection space 21) has exceeded the threshold value TH, it determines that an abnormality has occurred in the oil leakage recovery mechanism 20, cuts off the power supply to the motor 30, and opens the opening / closing valve 25, stopping the motor 30 and the work machine main body 10 while leaving the lubricant collection space 21 open to the atmosphere, and activates the warning notification means 50 such as a warning light 51 and an alarm 52.

[0089] In this way, the control device 26 brings the motor 30 to an emergency stop, thereby preventing the oil leakage recovery mechanism 20 from continuing to operate while the oil leakage recovery mechanism 20 is failing to recover the oil leakage. The occurrence of the recovery failure is notified to the operator by, for example, lighting up the warning light 51 or emitting a warning sound from the alarm 52, so that the operator can then take necessary measures such as replacing the shaft seal device 155 or clearing clogging of the recovery flow path 22.

[0090] In addition, when the motor 30 is stopped in an emergency, the opening / closing valve 25 is opened to the atmosphere through the air release passage 24, thereby reducing the internal pressure to atmospheric pressure, thereby preventing the lubricating oil in the lubricating oil collection space 21 from spraying out toward the motor 30 through the screw seals 23, 23' even when the motor 30 is stopped.

[0091] [Example of change] In the embodiment described with reference to Figures 1 to 4, the motor side end 15a of the shaft hole 15 is positioned within the motor housing 31, and the screw seals 23, 23' are formed up to the position of the end 15a of the shaft hole 15, so that the screw seals 23, 23' suck in air from within the motor housing 31 and send it out towards the lubricant oil collection space 21, and an air intake hole 70 is provided in the boss 16 that forms part of the motor housing 31, so that outside air can be introduced into the motor housing 31 through this air intake hole 70.

[0092] In contrast to this, in the embodiment shown in Figure 5, an intake chamber 28 isolated from the internal space of the motor housing 31 is provided on the outer periphery of the rotating shaft 131 located on the motor 30 side relative to the screw seal 23, and an intake flow path 71 having one end 71a connected to the intake chamber 28 and the other end 71b opening outside the motor housing 31 is formed within the thickness of the end cover 14a of the casing 14 of the speed increaser 13 in the illustrated embodiment.

[0093] As a result, the screw seal 23 draws in air from outside the motor housing 31 via the intake chamber 28 and the intake flow path 71, and the air thus drawn in is introduced into the lubricating oil collection space 21.

[0094] As shown in Figures 1 to 4, in a configuration in which the screw seals 23, 23' introduce air inside the motor housing 31 into the lubricant collection space 21, the air is sucked in by the screw seals 23, 23', creating a negative pressure inside the motor housing 31, so it is necessary to provide an intake hole 70 to take in outside air into the motor housing 31.However, since there is a risk that dust and other particles may be inhaled along with the air through this intake hole 70, the presence of the intake hole 70 is a factor that reduces the dustproof performance of the motor 30 (motor housing 31).

[0095] In contrast, in the configuration shown in Figure 5, air from outside the motor housing 31 is directly introduced into the intake chamber 28 located on the motor 30 side of the screw seal 23, thereby preventing negative pressure from building up inside the motor housing 31.As a result, there is no need to introduce outside air into the motor housing 31, and the motor housing 31 can be made into an airtight structure, making it possible to improve the dustproof performance of the motor 30 (motor housing 31) (for example, the IP protection rating, which is a protection rating standardized by the International Electrotechnical Commission). [Explanation of symbols]

[0096] 1 (Motor-driven) oil-free screw compressor 10 Work machine body (compressor body) 11 Low-pressure stage compressor body 11a Input shaft (of low-voltage compressor body) 12 High-pressure stage compressor body 12a Input shaft (of the high-pressure stage compressor body) 13 Speed ​​increasing device 131 Rotation axis 132 Drive gear 133,134 Driven gear 14 Casing (of speed increasing device) 14a End cover (of the speed increaser casing) 15 Shaft hole 15a End of shaft hole on the motor side 151,152 Bearings 153 Refueling space 154 Oil supply channel 155 Shaft sealing device 16. Boss 18 Oil mist filter 19 Oil Sump 20 Oil spill recovery mechanism 21 Lubricating oil collection space 22 Recovery channel 22a One end (of the recovery channel) 22b other end (of the recovery flow path) 23,23' Thread Seal 24 Air discharge channel 24a One end (of the air discharge channel) 24b Other end (of the air discharge channel) 25 On-off valve (solenoid on-off valve) 26 Control device 27 Pressure detection means 28 Intake chamber 30 Prime mover (motor) 31 Motor housing 50 Warning notification means 51 Warning light 52 Alarm 70 Air intake 71 Intake passage 71a One end (of intake passage) 71b other end (of intake passage) 210 Compressor body 215 Shaft hole 215a Motor side end of shaft hole 220 Oil spill recovery mechanism 221 Lubricating oil collection space 222 Recovery channel 222a One end (of the recovery channel) 222b other end (of recovery channel) 230 Prime mover (motor) 231 Motor housing 251 Bearings 255 Shaft sealing device 260 Storage Container 280 Intake control valve 281 Suction flow path TH threshold

Claims

1. An oil leakage recovery mechanism for a shaft seal portion, which includes a bearing housed in a shaft hole penetrating a wall surface of a casing between a work machine body and a prime mover, a rotating shaft connecting the work machine body and the prime mover being rotatably supported by the bearing, a shaft seal device on the prime mover side of the bearing that prevents leakage of lubricating oil supplied to the bearing, a lubricating oil collecting space on the prime mover side of the shaft seal device that collects lubricating oil that has passed through the shaft seal device, and a recovery flow path one end of which is connected to a lower end of the lubricating oil collecting space and that recovers the lubricating oil collected in the lubricating oil collecting space, A screw seal is provided at a position closer to the motor with respect to the lubricant oil collecting space, and the screw seal introduces air from the motor side into the lubricant oil collecting space by rotation of the rotating shaft. The oil leakage recovery mechanism for the shaft seal is characterized by including a pressure detection means for detecting when the pressure in the lubricating oil collection space rises above a predetermined threshold and outputting a detection signal.

2. The oil leakage recovery mechanism for the shaft seal portion as described in claim 1, characterized in that a control device is provided which receives the detection signal from the pressure detection means and stops operation of the prime mover and / or causes the warning notification means to issue a warning.

3. an air release flow path having one end connected to the lubricating oil collecting space and the other end open to the atmosphere, and an opening / closing valve for opening and closing the air release flow path; The control device When the detection signal is not received from the pressure detection means, the on-off valve is closed; 3. The mechanism for recovering oil leaked from a shaft seal according to claim 2, wherein the operation of the prime mover is stopped and the on-off valve is opened upon receiving the detection signal from the pressure detection means.

4. An oil leakage recovery mechanism for a shaft seal portion as described in any one of claims 1 to 3, characterized in that the outer diameter of the rotating shaft and the inner diameter of the shaft hole at the screw seal forming portion are formed in a tapered shape that becomes larger from the motor side toward the lubricating oil collection space side.

5. The end of the shaft hole on the motor side is disposed within the housing of the motor, 4. A shaft seal leak oil recovery mechanism as claimed in any one of claims 1 to 3, characterized in that an intake chamber isolated from the internal space of the housing is provided between the outer peripheral surface of the rotating shaft on the motor side and the inner peripheral surface of the shaft hole with respect to the thread seal, and an intake flow path is provided whose one end is connected to the intake chamber and whose other end opens outside the housing.

6. The end of the shaft hole on the motor side is disposed within the housing of the motor, 5. The oil leakage recovery mechanism for the shaft seal portion according to claim 4, characterized in that an intake chamber isolated from the internal space of the housing is provided between the outer peripheral surface of the rotating shaft on the motor side and the inner peripheral surface of the shaft hole with respect to the thread seal, and an intake flow path is provided whose one end is connected to the intake chamber and whose other end opens outside the housing.

7. A method for determining an abnormality in an oil leakage recovery mechanism of a shaft seal portion, the method comprising: accommodating a bearing in a shaft hole penetrating a wall surface of a casing between a work machine body and a prime mover; rotatably supporting a rotating shaft connecting the work machine body and the prime mover on the bearing; and providing, on the prime mover side of the bearing, a shaft seal device for preventing leakage of lubricating oil supplied to the bearing; a lubricating oil collecting space on the prime mover side of the shaft seal device for collecting lubricating oil that has passed through the shaft seal device; and a recovery flow path having one end connected to a lower end of the lubricating oil collecting space for recovering the lubricating oil collected in the lubricating oil collecting space, A screw seal is provided at a position closer to the motor with respect to the lubricant oil collecting space, which introduces air from the motor side into the lubricant oil collecting space by rotation of the rotating shaft. This allows air to continue to be introduced into the lubricant oil collecting space while the rotating shaft is rotating. monitoring the pressure in the lubricant oil collection space; A method for determining an abnormality in an oil leakage recovery mechanism of a shaft seal portion, characterized in that when the pressure in the lubricating oil collection space rises above a predetermined threshold, it is determined that an abnormality has occurred in the oil leakage recovery mechanism.

8. A method for controlling the operation of a work machine including a shaft seal device on the motor side of the bearing that prevents leakage of lubricating oil supplied to the bearing, a lubricating oil collecting space on the motor side of the shaft seal device that collects lubricating oil that has passed through the shaft seal device, and a recovery flow path that has one end connected to a lower end of the lubricating oil collecting space and that recovers the lubricating oil collected in the lubricating oil collecting space, the method comprising: accommodating a bearing in a shaft hole that penetrates a wall surface of a casing between the work machine body and the motor; A screw seal is provided at a position closer to the motor with respect to the lubricant oil collecting space, which introduces air from the motor side into the lubricant oil collecting space by rotation of the rotating shaft. This allows air to continue to be introduced into the lubricant oil collecting space while the rotating shaft is rotating. monitoring the pressure in the lubricant oil collection space; A method for controlling the operation of a work machine, characterized in that when the pressure in the lubricant oil collection space rises above a predetermined threshold, operation of the prime mover is stopped and / or a warning notification means is caused to issue a warning.

9. an air release flow path having one end connected to the lubricating oil collecting space and the other end open to the atmosphere, and an opening / closing valve for opening and closing the air release flow path; When the pressure in the lubricant oil collecting space is less than the threshold value, the on-off valve is closed, 9. The operation control method for a work machine according to claim 8, wherein operation of the prime mover is stopped and the on-off valve is opened when the pressure in the lubricant oil collecting space is equal to or greater than the threshold value.

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