JP6044156B2 - Oil drain structure, turbo compressor and turbo refrigerator - Google Patents

Description

  The present invention relates to an oil draining structure, a turbo compressor, and a turbo refrigerator.

  As a refrigerator, a turbo refrigerator having a turbo compressor that compresses and discharges a refrigerant by rotating an impeller with an electric motor is known. In a turbo compressor, lubricating oil is supplied from an oil tank to sliding parts such as a bearing of a rotating shaft of an electric motor and a bearing of a rotating shaft of an impeller. As described above, oil leakage from the seal portion that seals the periphery of the rotating shaft to another space is a problem at the site where the lubricating oil is supplied.

  Patent Document 1 listed below discloses a labyrinth seal device for an oil lubricated plummer block housing that prevents oil leakage of the lubricating oil and prevents the lubricating oil scattered inside the housing from reaching the labyrinth seal. In this labyrinth seal device, the wall portion together with the inner surface of the housing forms a drain groove, and the oil scattered on the upper inner surface of the housing is returned to the lower portion of the housing as an oil sump.

Japanese Patent Laid-Open No. 7-4529

  By the way, the lubricating oil secures the lubricity of the sliding part and suppresses the heat generation of the sliding part. In particular, in a part where the heat generation is large, a large amount of lubricating oil is sprayed from the nozzle. Most of the lubricating oil sprayed on the bearing returns to the oil tank through a predetermined path, but when a large amount of lubricating oil is sprayed in this way, it travels around the rotating shaft along the rotating shaft. It becomes easy to leak into the other space from the seal part to be sealed.

If the lubricating oil leaks to other spaces, the amount of lubricating oil that returns to the oil tank decreases, causing a phenomenon called so-called oil rising that lowers the oil level of the lubricating oil in the oil tank, and lubricates each sliding part. Oil supply may be insufficient.
The above-described conventional technology has a complicated configuration, and increases the cost and the number of parts when applied. In addition, if the structure is complicated, it is difficult to secure the robustness of each part, and it may cause a failure in a part where a large amount of lubricating oil is sprayed. In some cases, a predetermined function cannot be performed.

  The present invention has been made in view of the above problems, and an object thereof is to provide an oil draining structure, a turbo compressor, and a turbo refrigerator that are robust and have a high oil draining effect.

In order to solve the above-described problems, the present invention provides an oil draining structure for a seal portion that is provided on the back side of a bearing to which lubricating oil is sprayed from a nozzle and seals the periphery of a rotating shaft supported by the bearing. a is, the integrally rotatably provided on the rotary shaft, the front side of and the sealing portion a rear side of the bearing, have a stepped portion to increase the diameter of the rear side than the front side, the The step portion has a sleeve shape and is configured separately from the rotating shaft .
By adopting this configuration, in the present invention, by providing a stepped portion having a larger diameter on the front side of the seal portion, a large centrifugal force is generated in the stepped portion, so that the oil draining effect is enhanced. Thus, according to the present invention, it is possible to effectively prevent the lubricating oil from reaching the seal portion by a simple and robust structure in which a step portion is provided on the rotating shaft.

Moreover, in this invention, the said level | step-difference part employ | adopts the structure that it has the return shape for bouncing back the said lubricating oil which transmits the said rotating shaft to the near side.
By adopting this configuration, in the present invention, since the return shape is given to the stepped portion, even if the lubricant is transmitted along the rotating shaft, the lubricant can be rebounded to the near side by a large centrifugal force, The oil draining effect becomes higher.

Moreover, in this invention, the said level | step-difference part employ | adopts the structure that it has the inclined surface inclined to the near side with respect to the said rotating shaft as said return shape.
By adopting this configuration, in the present invention, since the step portion has an inclined surface that is inclined toward the front side with respect to the rotation axis, even if the lubricating oil travels along the rotation axis, the lubrication is performed using a large centrifugal force. Oil can be bounced back.

Moreover, in this invention, the structure that the said level | step-difference part is integrally formed with the said rotating shaft is employ | adopted.
By adopting this configuration, in the present invention, since the step portion is formed integrally with the rotating shaft, the number of parts is reduced, and a simpler and more robust structure can be achieved.

In the present invention, the seal portion includes a labyrinth seal and an oil seal provided on the front side of the labyrinth seal, and is provided so as to be rotatable integrally with the rotary shaft. And a groove portion for trapping the lubricating oil is employed on the back side of the labyrinth seal.
By adopting this configuration, in the present invention, even if the lubricating oil exceeds the oil seal, the lubricating oil can be trapped by the groove provided in the rotating shaft, so that the lubricating oil is prevented from reaching the labyrinth seal. can do.

In the present invention, a configuration is adopted in which a second stepped portion is provided on the rotating shaft so as to be integrally rotatable, and has a diameter on the back side larger than that on the near side across the groove portion.
By adopting this configuration, in the present invention, the second stepped portion can prevent the lubricating oil from exceeding the groove portion, and can more reliably suppress the lubricating oil from reaching the labyrinth seal. .

  Further, in the present invention, a turbo compressor that compresses gas by rotating an impeller with an electric motor, and as an oil draining structure for a seal portion of a rotating shaft of at least one of the electric motor and the impeller, The configuration of having the oil draining structure described above is adopted.

  In the present invention, the condenser that liquefies the compressed refrigerant, the evaporator that evaporates the liquefied refrigerant by the condenser and cools the object to be cooled, and the refrigerant evaporated by the evaporator A turbo refrigerator having a turbo compressor that compresses and supplies the turbo compressor to the condenser, and has the turbo compressor described above as the turbo compressor.

  According to the present invention, an oil removal structure, a turbo compressor, and a turbo refrigerator that are robust and have a high oil removal effect can be obtained.

It is a systematic diagram of the turbo refrigerator in 1st Embodiment of this invention. It is sectional drawing which shows the structure of the oil draining structure in 1st Embodiment of this invention. It is sectional drawing which shows the structure of the oil draining structure in 2nd Embodiment of this invention. It is sectional drawing which shows the structure of the oil draining structure in 3rd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a system diagram of a turbo chiller 1 according to a first embodiment of the present invention.
The turbo refrigerator 1 of the present embodiment uses, for example, chlorofluorocarbon as a refrigerant and air-conditioning cold water as a cooling object. As shown in FIG. 1, the turbo refrigerator 1 includes a condenser 2, an economizer 3, an evaporator 4, and a turbo compressor 5.

  The condenser 2 is connected to the gas discharge pipe 5a of the turbo compressor 5 via the flow path R1. Refrigerant (compressed refrigerant gas X1) compressed by the turbo compressor 5 is supplied to the condenser 2 through the flow path R1. The condenser 2 liquefies the compressed refrigerant gas X1. The condenser 2 includes a heat transfer pipe 2a through which cooling water flows, and cools the compressed refrigerant gas X1 by heat exchange between the compressed refrigerant gas X1 and the cooling water.

  The compressed refrigerant gas X1 is cooled by heat exchange with the cooling water, liquefied, becomes refrigerant liquid X2, and accumulates at the bottom of the condenser 2. The bottom of the condenser 2 is connected to the economizer 3 via the flow path R2. An expansion valve 6 for reducing the pressure of the refrigerant liquid X2 is provided in the flow path R2. The economizer 3 is supplied with the refrigerant liquid X2 decompressed by the expansion valve 6 through the flow path R2. The economizer 3 temporarily stores the decompressed refrigerant liquid X2, and separates the refrigerant into a liquid phase and a gas phase.

  The top of the economizer 3 is connected to the economizer connecting pipe 5b of the turbo compressor 5 through the flow path R3. The gas phase component X3 of the refrigerant separated by the economizer 3 is supplied to the turbo compressor 5 through the flow path R3 to the second compression stage 12 without passing through the evaporator 4 and the first compression stage 11, and the efficiency Is to increase. On the other hand, the bottom of the economizer 3 is connected to the evaporator 4 via a flow path R4. The flow path R4 is provided with an expansion valve 7 for further reducing the pressure of the refrigerant liquid X2.

  The evaporator 4 is supplied with the refrigerant liquid X2 further reduced in pressure by the expansion valve 7 through the flow path R4. The evaporator 4 evaporates the refrigerant liquid X2 and cools the cold water by the heat of vaporization. The evaporator 4 includes a heat transfer tube 4a through which cold water flows, and cools the cold water and evaporates the refrigerant liquid X2 by heat exchange between the refrigerant liquid X2 and the cold water. Refrigerant liquid X2 takes heat by heat exchange with cold water and evaporates to become refrigerant gas X4.

  The top of the evaporator 4 is connected to a gas suction pipe 5c of the turbo compressor 5 via a flow path R5. The refrigerant gas X4 evaporated in the evaporator 4 is supplied to the turbo compressor 5 through the flow path R5. The turbo compressor 5 compresses the evaporated refrigerant gas X4 and supplies it to the condenser 2 as the compressed refrigerant gas X1. The turbo compressor 5 is a two-stage compressor including a first compression stage 11 that compresses the refrigerant gas X4 and a second compression stage 12 that further compresses the refrigerant compressed in one stage.

  The first compression stage 11 is provided with an impeller 13, and the second compression stage 12 is provided with an impeller 14, which are connected by a rotating shaft 15. The turbo compressor 5 rotates the impellers 13 and 14 by the electric motor 10 to compress the refrigerant. The impellers 13 and 14 are radial impellers, and have blades including a three-dimensional twist (not shown) that guides the refrigerant sucked in the axial direction in the radial direction.

  An inlet guide vane 16 for adjusting the suction amount of the first compression stage 11 is provided in the gas suction pipe 5c. The inlet guide vane 16 is rotatable so that the apparent area from the flow direction of the refrigerant gas X4 can be changed. Diffuser flow paths are provided around the impellers 13 and 14, respectively, and the refrigerant derived in the radial direction is compressed and pressurized in the flow paths, and further is scrolled by a scroll flow path provided therearound. Can be supplied to the compression stage. An outlet throttle valve 17 is provided around the impeller 14 so that the discharge amount from the gas discharge pipe 5a can be controlled.

  The turbo compressor 5 includes a sealed casing 20. The housing 20 is partitioned into a compression flow path space S1, a first bearing housing space S2, a motor housing space S3, a gear unit housing space S4, and a second bearing housing space S5. Impellers 13 and 14 are provided in the compression flow path space S1. The rotating shaft 15 that connects the impellers 13 and 14 is provided so as to be inserted into the compression flow path space S1, the first bearing housing space S2, and the gear unit housing space S4. A bearing 21 that supports the rotary shaft 15 is provided in the first bearing housing space S2.

  In the motor housing space S3, a stator 22, a rotor 23, and a rotating shaft 24 connected to the rotor 23 are provided. The rotating shaft 24 is provided so as to be inserted into the motor housing space S3, the gear unit housing space S4, and the second bearing housing space S5. In the second bearing housing space S5, a bearing 31 that supports the non-load side of the rotating shaft 24 is provided. A gear unit 25, bearings 26 and 27, and an oil tank 28 are provided in the gear unit housing space S4.

  The gear unit 25 includes a large-diameter gear 29 that is fixed to the rotary shaft 24, and a small-diameter gear 30 that is fixed to the rotary shaft 15 and meshes with the large-diameter gear 29. The gear unit 25 transmits the rotational driving force so that the rotational speed of the rotary shaft 15 increases (increases) with respect to the rotational speed of the rotary shaft 24. The bearing 26 supports the rotating shaft 24. The bearing 27 supports the rotating shaft 15. The oil tank 28 stores lubricating oil supplied to each sliding portion such as the bearings 21, 26, 27, and 31.

  Such a casing 20 is provided with seal portions 32 and 33 for sealing the periphery of the rotary shaft 15 between the compression flow path space S1 and the first bearing housing space S2. Further, the casing 20 is provided with a seal portion 34 that seals the periphery of the rotary shaft 15 between the compression flow path space S1 and the gear unit accommodation space S4. The casing 20 is provided with a seal portion 35 that seals the periphery of the rotary shaft 24 between the gear unit accommodation space S4 and the motor accommodation space S3. Further, the casing 20 is provided with a seal portion 36 that seals the periphery of the rotary shaft 24 between the motor housing space S3 and the second bearing housing space S5.

  The motor housing space S3 is connected to the condenser 2 via the flow path R6. The refrigerant liquid X2 is supplied from the condenser 2 through the flow path R6 to the motor housing space S3. The refrigerant liquid X2 supplied to the motor housing space S3 flows around the stator 22, and cools the motor housing space S3 by heat exchange between the stator 22 and the periphery thereof. The motor housing space S3 is connected to the evaporator 4 via the flow path R6. The evaporator 4 is supplied with the refrigerant liquid X2 that has lost heat in the motor housing space S3 through the flow path R7.

  The oil tank 28 has an oil supply pump 37. The oil supply pump 37 is connected to the second bearing housing space S5 via the flow path R8. Lubricating oil is supplied from the oil tank 28 through the flow path R8 to the second bearing housing space S5. The lubricating oil supplied to the second bearing housing space S5 is supplied to the bearing 31 to ensure lubricity of the sliding portion of the rotating shaft 24 and to suppress (cool) heat generation of the sliding portion. The second bearing housing space S5 is connected to the oil tank 28 via the flow path R9. The lubricating oil supplied to the second bearing housing space S5 returns to the oil tank 28 through the flow path R9.

Here, when the lubricating oil supplied to the second bearing housing space S5 leaks from the seal portion 36 to the motor housing space S3, the lubricating oil passes through the flow path R7 from the motor housing space S3 to the evaporator. 4, the lubricating oil returning to the oil tank 28 is reduced and the liquid level is lowered.
Hereinafter, the configuration of the oil draining structure for preventing the oil rising phenomenon will be described with reference to FIG.

FIG. 2 is a cross-sectional view showing the configuration of the oil draining structure A in the first embodiment of the present invention.
As shown in FIG. 2, the end of the rotating shaft 24 on the side opposite to the load is disposed in the second bearing housing space S5. The rotary shaft 24 is rotatably supported by a ball bearing 31. An inner ring 31 a of the bearing 31 is fixed to the rotating shaft 24 by a nut 40. The outer ring 31 b of the bearing 31 is fixed to the housing 20 by a seal housing 41. For this reason, the inner ring 31 a rotates with the rotary shaft 24 in a state where the outer ring 31 b is fixed.

  Above the second bearing housing space S5, a nozzle 42 for spraying lubricating oil onto the bearing 31 is provided. The nozzle 42 is connected to the flow path R8. The nozzle 42 sprays the lubricating oil in the oil tank 28 pressurized by the oil supply pump 37 toward the bearing 31 in the axial direction. The bottom of the second bearing housing space S5 is connected to the flow path R9. The lubricating oil sprayed on the bearing 31 accumulates at the bottom of the second bearing housing space S5, and is returned to the oil tank 28 through the flow path R9.

  A seal portion 36 is provided on the back side of the bearing 31 to which the lubricating oil is sprayed from the nozzle 42. The seal portion 36 includes a labyrinth seal 43 and an oil seal 44. The labyrinth seal 43 is provided on the back side and the oil seal 44 is provided on the front side with respect to the nozzle 42. The labyrinth seal 43 has a plurality of fins facing the outer peripheral surface of the rotating shaft 24. The oil seal 44 is longer than the fins of the labyrinth seal 43 and has a plurality of fins facing the outer peripheral surface of the rotating shaft 24.

  The rotary shaft 24 has a stepped portion 50 which is on the back side of the bearing 31 and on the front side of the seal portion 36 and has a diameter on the back side larger than that on the front side. The step portion 50 is formed integrally with the rotary shaft 24 and can rotate integrally with the rotary shaft 24. The step portion 50 has a step surface 51 that is perpendicular to the rotating shaft 24. The step surface 51 is formed in an annular shape in the circumferential direction of the rotating shaft 24. A space is formed around the stepped surface 51 by the bearing 31 and the seal housing 41 so that the lubricating oil can flow.

  The rotating shaft 24 has a groove 52 that traps the invading lubricating oil on the back side of the oil seal 44 and on the front side of the labyrinth seal 43. The groove 52 is formed integrally with the rotary shaft 24 and can rotate integrally with the rotary shaft 24. The groove 52 is formed in an annular shape with a predetermined depth in the circumferential direction on the outer peripheral surface of the rotating shaft 24. An opening 53 for returning the lubricating oil to the bottom of the second bearing housing space S5 is provided in the lower part of the seal housing 41 corresponding to the groove 52. The opening 53 communicates with the space around the step surface 51.

  Then, the effect | action of the oil draining structure A is demonstrated.

  As shown in FIG. 2, the lubricating oil supplied from the nozzle 42 is sprayed on the bearing 31 in the axial direction. The lubricating oil sprayed on the bearing 31 reduces the friction of the bearing 31 and absorbs heat from the bearing 31 to suppress the temperature rise of the bearing 31. A part of the lubricating oil sprayed on the bearing 31 flows out to the inner side of the bearing 31 as it is, and flows in the axial direction toward the seal portion 36 along the outer peripheral surface of the rotating shaft 24.

  The oil draining structure A is provided on the rotary shaft 24 so as to be able to rotate integrally, and has a stepped portion 50 on the back side of the bearing 31 and on the front side of the seal portion 36 that has a larger diameter on the back side than on the front side. . The step portion 50 has a step surface 51 perpendicular to the rotating shaft 24, and prevents the progress of the lubricating oil on the front side of the seal portion 36. Further, the step portion 50 is rotated integrally with the rotary shaft 24 at a high speed (for example, 3600 rpm), so that the damped lubricating oil is repelled radially outward of the rotary shaft 24 by the centrifugal force, thereby removing oil drainage. Do.

  As described above, in the present embodiment, by providing the stepped portion 50 having a larger diameter on the front side of the seal portion 36, a large centrifugal force is generated in the stepped portion 50, so that the oil draining effect is enhanced. Therefore, according to this oil draining structure A, it is possible to effectively prevent the lubricating oil from reaching the seal portion 36 by a simple and robust structure in which the step portion 50 is provided on the rotating shaft 24. In the present embodiment, since the step portion 50 is formed integrally with the rotating shaft 24, the number of parts is reduced, and a simpler and more robust structure can be achieved.

  Further, the oil draining structure A is provided on the rotary shaft 24 so as to be integrally rotatable, and has a groove portion 52 that traps lubricating oil on the back side of the oil seal 44 and on the near side of the labyrinth seal 43. The groove portion 52 traps a minute amount of lubricating oil that has entered the back side from the oil seal 44 beyond the step portion 50 by the groove shape. According to this oil draining structure A, it is possible to prevent the lubricating oil from reaching the labyrinth seal 43 by the groove portion 52, so that leakage of the lubricating oil from the seal portion 36 can be prevented more reliably.

  In this embodiment, since the groove part 52 is integrally formed with the rotating shaft 24, it can be set as a simple and robust structure similarly. The lubricating oil trapped in the groove 52 is guided below the rotary shaft 24 and introduced into the opening 53 formed in the seal housing 41. The lubricating oil introduced into the opening 53 merges with the lubricating oil drained by the stepped portion 50 and accumulates at the bottom of the second bearing housing space S5. Then, the lubricating oil accumulated at the bottom of the second bearing housing space S5 is returned to the oil tank 28 from the flow path R9.

  Therefore, according to the above-described embodiment, the oil for the seal portion 36 that seals the periphery of the rotating shaft 24 provided on the back side of the bearing 31 to which the lubricating oil is sprayed from the nozzle 42 and supported by the bearing 31. A stepped portion 50 which is a cutting structure A and is provided on the rotary shaft 24 so as to be integrally rotatable, and on the back side of the bearing 31 and on the front side of the seal portion 36, has a larger diameter on the back side than on the front side. By adopting the configuration of having the oil removal structure A, the oil removal structure A which is robust and has a high oil removal effect is obtained. Further, according to the turbo compressor 5 and the turbo refrigerator 1 having the oil draining structure A, oil leakage to the evaporator 4 through the seal portion 36 is prevented, and occurrence of an oil rising phenomenon in the oil tank 28 is prevented. be able to.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the following description, the same or equivalent components as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

FIG. 2 is a cross-sectional view showing the configuration of the oil draining structure A in the second embodiment of the present invention.
As shown in FIG. 2, the second embodiment is different from the above-described embodiment in that the step surface 51 b of the step portion 50 has a return shape.

  The step portion 50 according to the second embodiment can rotate integrally with the rotary shaft 24, but is separate from the rotary shaft 24. In the second embodiment, the stepped portion 50 is formed in a sleeve shape from the viewpoint of the workability of the shape of the stepped surface 51b, and is separated from the rotating shaft 24. On the outer peripheral surface of the stepped portion 50, a groove portion 52 for trapping lubricating oil is provided on the back side of the oil seal 44 and on the near side of the labyrinth seal 43, as in the above embodiment.

  The step portion 50 has a return shape for repelling the lubricating oil transmitted through the rotating shaft 24 to the near side. The stepped portion 50 has a stepped surface 51b which is an inclined surface inclined to the near side with respect to the rotating shaft 24 as the return shape. The step surface 51b is provided such that an angle with respect to the rotation shaft 24 is an acute angle in the longitudinal axis section. The step surface 51b is formed in an annular shape in the circumferential direction of the rotary shaft 24 at the end surface of the sleeve.

According to the oil draining structure A of the second embodiment having the above-described configuration, the following action is obtained.
First, the lubricating oil that flows out to the back side of the bearing 31 and travels through the rotary shaft 24 can be blocked by the step surface 51 b of the step portion 50. Further, the step portion 50 can perform oil draining by rotating at a high speed integrally with the rotary shaft 24. Here, since the step surface 51b of the second embodiment is an inclined surface that is inclined toward the front with respect to the rotation shaft 24, the dammed lubricating oil is rebounded to the front side by using the large centrifugal force. Can do.

  According to such a return shape of the stepped portion 50, the lubricating oil is rebounded to the near side away from the seal portion 36, so that it is difficult for the lubricating oil to get over the stepped portion 50. For this reason, according to the oil draining structure A of 2nd Embodiment, the oil draining effect in the level | step-difference part 50 becomes higher. Therefore, oil leakage at the seal portion 36 can be prevented more reliably.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In the following description, the same or equivalent components as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

FIG. 3 is a cross-sectional view showing the configuration of the oil draining structure A in the third embodiment of the present invention.
As shown in FIG. 3, the third embodiment differs from the above embodiment in that the rotating shaft 24 has a second stepped portion 54.

  The rotary shaft 24 of the third embodiment has a second step portion 54 that has a diameter on the back side larger than that on the near side across the groove portion 52. The second step portion 54 is formed integrally with the rotary shaft 24 and can rotate integrally with the rotary shaft 24. The second step portion 54 has a step surface 55 that is perpendicular to the rotating shaft 24. The step surface 55 is formed in an annular shape in the circumferential direction of the rotating shaft 24. A space is formed around the step surface 55 by the seal housing 41 so that the lubricating oil can flow.

According to the oil draining structure A of the third embodiment having the above-described configuration, the following action is obtained.
First, the lubricating oil that has entered the back side from the oil seal 44 beyond the stepped portion 50 can be trapped by the groove portion 52. Here, in 3rd Embodiment, since the back | inner side from the groove part 52 is a wall high by the 2nd level | step-difference part 54, it can prevent that the trapped lubricating oil reaches the labyrinth seal 43 beyond the groove part 52. it can. Therefore, according to the third embodiment, oil leakage at the seal portion 36 can be more reliably prevented.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, in the above embodiment, one stepped portion 50 is provided on the back side of the bearing 31 and on the front side of the seal portion 36, but the present invention is not limited to this configuration and may be multistaged.

  Further, for example, in the above embodiment, an inclined surface inclined toward the front side with respect to the rotation shaft 24 is adopted as the return shape, but the present invention is not limited to this configuration, and may be an R-shaped curved surface.

  Further, for example, in the above-described embodiment, the oil draining structure A of the present invention is applied for the seal portion 36. However, the present invention is not limited to this configuration, and for example, the oil draining structure A of the present invention is applied to the seal portion. It may be applied for 32, 33, 34, 35.

  DESCRIPTION OF SYMBOLS 1 ... Turbo refrigerator, 2 ... Condenser, 4 ... Evaporator, 5 ... Turbo compressor, 10 ... Electric motor, 13, 14 ... Impeller, 24 ... Rotating shaft, 31 ... Bearing, 36 ... Seal part, 42 ... Nozzle, 43 ... Labyrinth seal, 44 ... Oil seal, 50 ... Stepped portion, 51 ... Stepped surface, 52 ... Groove portion, 54 ... Second stepped portion, A ... Oil draining structure

Claims (7)

An oil draining structure for a seal portion that is provided on the back side of a bearing to which lubricating oil is sprayed from a nozzle and seals the periphery of a rotating shaft supported by the bearing,
The integrally rotatably provided on the rotary shaft, the front side of and the sealing portion a rear side of the bearing, have a stepped portion to increase the diameter of the rear side than the front side,
The oil draining structure , wherein the stepped portion is sleeve-shaped and is separate from the rotating shaft .   2. The oil draining structure according to claim 1, wherein the stepped portion has a return shape for repelling the lubricating oil transmitted through the rotating shaft to the near side.   3. The oil draining structure according to claim 2, wherein the stepped portion has an inclined surface inclined to the near side with respect to the rotation axis as the return shape. The seal portion includes a labyrinth seal and an oil seal provided on the near side of the labyrinth seal,
Wherein the rotary shaft integrally provided with rotatable, in front of and the labyrinth seal an inner side of the oil seal, according to claim 1-3, wherein the lubricating oil has a groove to trap, it is characterized by The oil draining structure according to any one of the above. 5. The oil draining structure according to claim 4 , further comprising a second stepped portion that is provided on the rotating shaft so as to be integrally rotatable, and has a diameter on the back side larger than that on the near side across the groove portion. A turbo compressor that compresses gas by rotating an impeller with an electric motor,
A turbo compression comprising the oil drainage structure according to any one of claims 1 to 5 as an oil drainage structure for a seal portion of a rotating shaft of at least one of the electric motor and the impeller. Machine. A condenser for liquefying the compressed refrigerant;
An evaporator that evaporates the liquefied refrigerant by the condenser and cools an object to be cooled;
A turbo compressor having a turbo compressor that compresses the refrigerant evaporated by the evaporator and supplies the compressed refrigerant to the condenser;
A turbo refrigerator having the turbo compressor according to claim 6 as the turbo compressor.

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