JP2007303431A - Thrust bearing unit, turbo compressor using the same, and assembling method of thrust bearing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid a bend of a shaft caused by assembling in a thrust bearing unit of a turbo compressor. <P>SOLUTION: The turbo compressor transmits power of a drive unit to an impeller via a step-up gear. The step-up gear has a gear wheel 1 formed in a helical gear and a rotary drive shaft 2 with thrust bearings 8a and 8b formed on both side sections of the gear wheel 1. A rotary driven shaft 4 has a small gear 3 engaged with the gear wheel and formed in a helical gear, thrust collars 6a and 6b arranged on both side sections of the small gear 3, and thrust collar fixing means 7a to 7d arranged at a counter small gear side of the thrust collars. The thrust collars are press-fitted into a rotary driven shaft. A ring-shaped fixing groove 9 is formed on the rotary driven shaft, and the width of the thrust collar fixing means before fitting the thrust collar fixing means into the ring-shaped groove is formed wider than the width of the groove. Preload is generated by extending the rotary driven shaft so that the thrust collar fixing means is fitted into the groove. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thrust bearing device, and more particularly to a thrust bearing device suitable for use in a turbo compressor.

  An example of a conventional thrust bearing used in a compressor or the like is described in Patent Document 1. In the thrust bearing described in this publication, sleeves that do not come into contact with the shaft are provided on both sides of the shaft side base portion of the thrust collar in order to fasten the thrust collar to the shaft with low hydraulic pressure and facilitate assembly. And the same taper as the taper formed in the shaft is formed in the fitting portion that bulges from both ends of the sleeve to the shaft side. The taper of the shaft and the taper of the fitting portion are tightly fitted.

Japanese Utility Model Publication No. 6-75503

  In the thrust bearing described in Patent Document 1, since the thrust collar is fixed to the rotating shaft with an interference fit, a larger tightening margin can be obtained as compared with the case where the thrust collar is press-fitted into the shaft. However, when the power of the driving machine is transmitted to the rotating shaft via the speed increaser, as in the case of a turbo compressor, the inner diameter portion is enlarged due to the centrifugal force acting on the inner diameter portion of the thrust collar. The effective margin is reduced. As a result, the fastening force between the rotating shaft and the thrust collar is reduced, and the thrust collar may move irregularly. If the thrust collar moves irregularly, abnormal vibration is generated in the shaft portion, and the impeller attached to the rotating shaft may be damaged.

  In order to solve this problem, a method in which a thrust collar is shrink-fitted on a rotating shaft has been frequently used. When this shrink fitting is used, a much larger tightening margin can be obtained as compared with the case where the thrust collar is hydraulically fitted to the rotating shaft. However, when the thrust collar is shrink-fitted onto the shaft, the thrust collar is once heated to a temperature higher than that of the rotating shaft and then fitted to the rotating shaft. Temperature distribution occurs in the circumferential direction and the axial direction. This temperature distribution causes the rotating shaft to bend when the thrust collar is gradually cooled.

  The bending of the rotating shaft that occurs when the thrust collar is gradually cooled is within an allowable range in terms of strength of the rotating shaft, and there is no problem. However, in a turbo compressor or the like that transmits power from the drive unit to the impeller via the speed increaser, the gearing of the speed increaser is affected. That is, the center distance of the pair of gears fluctuates, causing uneven rotation on the rotating shaft. Unevenness of rotation of the rotating shaft can generate a translational force on the gear shaft and contribute to an increase in shaft vibration.

  The present invention has been made to solve the above-described problems of the prior art, and an object thereof is to reduce the bending of the rotating shaft caused by attaching a thrust bearing device to the rotating shaft of a turbo compressor or the like. . Another object of the present invention is to reduce noise radiated from a gear box through propagation of vibration generated in a rotating shaft portion of a turbo compressor. Thereby, it aims at improving the reliability of a turbo compressor.

  A feature of the present invention that achieves the above object is that, in a turbo compressor that transmits the power of a drive machine to an impeller through a speed increaser, the speed increaser has a large gear formed on a helical gear and the large gear. A rotary drive shaft having thrust bearing surfaces formed on both side portions, a small gear meshing with the large gear, a helical gear formed on a helical gear, a thrust collar disposed on both side portions of the small gear, and the thrust collar A rotating driven shaft having a thrust collar fixing means disposed on the counter-small gear side, the thrust collar is press-fitted into the rotating driven shaft, and a ring-shaped groove is formed on the rotating driven shaft. The width of the thrust collar fixing means before the collar fixing means is fitted into the ring-shaped groove is formed wider than the width of the groove, and the thrust collar fixing means is fitted into the groove by extending the rotary driven shaft. Combine and preload It lies in the fact that caused.

  In this feature, the thrust collar fixing means is formed in a split shape, and when the thrust collar fixing means is fitted in the groove, the rotating driven shaft is heated or pulled from both ends of the rotating driven shaft. It is desirable to stretch.

  Another feature of the present invention that achieves the above object is a bearing device for use in a turbo compressor, which is a thrust bearing formed on both side surfaces of a large gear that constitutes a speed increasing gear, and an oil film is interposed in the thrust bearing. A pair of thrust collars that slide in sliding motion, and a pair of thrust collar fixing means that is disposed on the side of the thrust collar opposite to the small gear and that holds the thrust collar on a rotary driven shaft provided with a small gear. The collar is press-fitted into the rotary driven shaft, and a ring-shaped groove is formed on the rotary driven shaft.The width of the thrust collar fixing means before the thrust collar fixing means is fitted into the ring-shaped groove is: The groove is formed wider than the width of the groove, and the rotary driven shaft is extended to fit the thrust collar fixing means into the groove to generate preload.

  In this feature, the thrust collar fixing means is formed in a split shape, and the width before the thrust collar fixing means is fitted into the groove formed on the rotary driven shaft is wider than the width of the groove. Is desirable.

  Still another feature of the present invention that achieves the above object is to provide a thrust bearing device comprising a pair of thrust collars that slide through an oil film on thrust bearings formed on both sides of a large gear. Is inserted into a rotary driven shaft provided with a small gear that meshes with the large gear, and a thrust collar fixing means for pressing the thrust collar from the axial direction is formed in a groove formed in the rotary driven shaft, with a margin in the axial direction. It is because it was made to fit.

  In this feature, when the thrust collar fixing means is fitted to the rotary driven shaft with an interference in the axial direction, the rotary driven shaft is heated, and the width of the groove formed on the shaft is set to the thrust collar. It is better to expand the width of the fixing means or pull the rotary driven shaft in the axial direction so that the width of the groove formed in the shaft is wider than the width of the thrust collar fixing means. When the thrust collar fixing means is formed in a split shape and is fitted to the rotating driven shaft with a margin in the axial direction, the outer diameter of the rotating driven shaft is fixed to the split collar fixing means. It is preferable to fit in the inner diameter side direction from the side and fasten the fitted thrust collar fixing means using the fastening means.

  According to the present invention, since the thrust collar used in the thrust bearing device is pressed on the two side surfaces of the rotating shaft, the rotating shaft is not thermally deformed, and the bending that may occur on the small gear shaft is avoided. it can. As a result, vibration and noise generated at the rotating shaft of the turbo compressor can be reduced, and the reliability of the turbo compressor is improved.

  An embodiment of a turbo compressor according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing the main part of a two-stage centrifugal compressor 20. A large gear shaft 2 connected to a driving machine (not shown) through a coupling is provided with a large gear 1. A centrifugal impeller 5a for the first stage compression section and a centrifugal impeller 5b for the second stage compression section are attached to both ends of the small gear shaft 4 provided with the small gear 3 that meshes with the large gear 1. Yes. Both the large gear 1 and the small gear 3 are formed of helical teeth.

  Radial bearings (not shown) are attached to both ends of the rotary shaft (large gear shaft) 2 provided with the large gear 1 to support a radial load acting on the large gear shaft 2 and Make it rotatable. Although not shown, a thrust bearing is also attached to the large gear shaft 2. Conical sliding surfaces 8 a and 8 b are formed on both side surfaces of the large gear 1 from the position where the outer diameter is smaller than that of the large gear 1 toward the inner diameter side. The sliding surfaces 8a and 8b slide with thrust collars 6a and 6b described later.

In the rotation shaft (small gear shaft) 4 provided with the small gear 3, thrust collars 6a and 6b are arranged at positions corresponding to the sliding surfaces 8a and 8b formed on the side surface of the large gear 1. The thrust collars 6a and 6b are formed to have a larger diameter than the small gear 3, and have a conical surface that is substantially the same inclination and opposite to the sliding surface formed on the side of the large gear 1. Yes. Therefore, the thrust collars 6a and 6b sandwich the small gear 3 from both side surfaces. A radial bearing (not shown) is disposed between the small gear 3 and the impellers 5 a and 5 b, and the radial bearing rotatably supports a radial load acting on the small gear shaft 4.

A pair of thrust collar fixing spacers formed in a split ring shape on the back side of each thrust collar 6a, 6b, that is, on the impeller 5a, 5b side, in order to hold the thrust collar 6a, 6b in the axial direction. 7a, 7b; 7c, 7d are arranged. In order to connect the thrust collar fixing spacers 7a and 7b, a thrust hole 11a is formed in the thrust collar fixing spacer 7a, and a screw hole 11b is formed in the thrust collar fixing spacer 7b. Similarly, a thrust hole 11c is formed in the thrust collar fixing spacer 7c, and a screw hole 11d is formed in the thrust collar fixing spacer 7d. From this, holes 11a, 11c and screw holes 11b,
A tightening screw is screwed into 11d.

  In the turbo compressor 20 configured as described above, when a driving machine (not shown) is driven to rotate, the large gear shaft 2 connected via the coupling rotates, and the large gear integrated with the large gear shaft 2 is rotated. 1 also rotates. The small gear 3 that meshes with the large gear 1 rotates synchronously with the large gear 1, and the impellers 5a and 5b attached to both ends of the small gear shaft 4 with which the small gear 3 is integrated rotate. When the impellers 5a and 5b that form a flow path with a casing (not shown) rotate, the gas sucked from the first stage impeller 5a rises in pressure, and after being led from the casing to the intercooler, the second The air is sucked into the step impeller 5b and further boosted. And after cooling with an aftercooler, it is led to a demand source. The large gear 1 and the small gear 3 are accommodated in a gear casing (not shown) and are lubricated with lubricating oil supplied to the meshing surface.

By the way, in this embodiment, in order to generate compressed gas, the gear ratio between the large gear 1 and the small gear 3 is set to 10 times or more, and the rotational speed of the motor as a driving machine is increased. And the rotational speed of each impeller 5a, 5b is raised to about 50,000 rotations / minute which is a predetermined rotational speed. At that time, torque corresponding to the work of the impellers 5a and 5b is applied to the small gear shaft 4 provided with the small gear 3. That is, torque is transmitted from the large gear 1 to the small gear 3 by a torque corresponding to the work of the impellers 5a and 5b.

  Here, since both the large gear 1 and the small gear 3 are helical gears as described above, this transmission torque generates an axial load component. Furthermore, an axial load component is generated even when the impellers 5a and 5b compress the gas. Therefore, the resultant force of the axial load component of the transmission torque and the axial load component due to the compression action of the impeller is supported as an axial load on a thrust bearing attached to at least one of the large gear shafts 2.

Here, the rotational speed of the large gear shaft 2 provided with the large gear 1 is 1 / lower than the rotational speed of the small gear shaft 4.
When the thrust bearing is attached to the large gear shaft 2 and supported by the load, the bearing loss that increases in accordance with the rotational speed can be reduced as compared with the case where the thrust bearing is attached to the small gear shaft 4. Therefore, as described above, in this embodiment, a pair of thrust collars 6a and 6b is attached to the small gear shaft 4 provided with the small gear 3 in order to reduce bearing loss. Further, conical sliding surfaces 8a and 8b are formed on the side surfaces of the large gear 1, and are brought into sliding contact with the sliding surfaces of the thrust collars 6a and 6b through an oil film of lubricating oil. As a result, the axial load generated on the small gear shaft 4 of the small gear 3 is transmitted to the thrust bearing provided on the large gear shaft 2 of the large gear 1. In a machine that rotates at a high speed, such as the small gear shaft 4 of the small gear 3, the loss in the thrust collar is significantly smaller than the loss when the thrust bearing is provided.

Thrust bearings 8a and 8b are formed on the large gear shaft 2 of the large gear 1, and the thrust bearing 8a,
Details of a mechanism for transmitting a thrust load from the thrust collars 6a and 6b provided on the small gear shaft 4 of the small gear 3 in 8b will be described with reference to FIG. FIG. 2 is a perspective view of the thrust bearings 8a and 8b and the thrust collars 6a and 6b, and is a diagram in the middle of assembly.

  In the small gear shaft 4 formed integrally with the small gear 3 shown in this embodiment, the thrust collar fixing spacers 7a and 7b are larger than the outer diameters of the thrust collars 6a and 6b arranged on both sides of the small gear 3. A ring-shaped groove structure having a small outer diameter is employed. Further, the end side of the thrust collar fixing spacers 7a and 7b is made larger in diameter than the thrust collar fixing spacers 7a and 7b. The reason for this is as follows.

  In order to transmit the axial load generated in the small gear shaft 4 to the thrust bearings 8a and 8b on the large gear 1 side, the thrust collars 6a and 6b are press-fitted and fixed to the small gear shaft 4 provided with the small gear 3. ing. In press-fitting, the diameter of the fitting portion of the small gear shaft 4 is formed slightly larger than the inner diameter of the thrust collars 6a and 6b, and the thrust collars 6a and 6b are pushed out in the axial direction by hydraulic pressure or the like. As a result, when stationary, the small gear shaft 4 bites into the inner diameter side of the thrust collars 6a and 6b, and a sufficient fixing force can be obtained.

  On the other hand, when the small gear shaft 4 is rotated at a high speed, the inner diameters of the thrust collars 6a and 6b are enlarged by the centrifugal force acting on the thrust collars 6a and 6b. The tightening allowance is reduced and the tightening force is insufficient. In order to solve this problem, the inner diameters of the thrust collars 6a and 6b when stationary may be made sufficiently smaller than the outer diameter of the small gear shaft 4. However, in this case, the tightening allowance increases and it becomes difficult to hydraulically fit the thrust collars 6a and 6b to the rotating shaft, and it is necessary to use shrink fitting or the like. The shrinkage fit causes the above-mentioned problems.

  Therefore, in this embodiment, the thrust collars 6a and 6b are brought into contact with the thrust collar fixing spacers 7a and 7b; 7c and 7d from the counter-small gear side, so that a preload is applied in the axial direction to supplement the fixing force. Yes. Specifically, the thrust collar fixing spacers 7a and 7b; The small gear shaft 4 provided with the small gear 3 is formed with a fixing groove 9 which is slightly narrower than the width of the thrust collar fixing spacers 7a to 7d in a normal state.

  When the thrust collar fixing spacers 7a to 7d are fitted into the fixing groove 9, both ends of the small gear shaft 4 on which the small gear is formed are pulled with tensions 10a and 10b, and the width of the fixing groove 9 is set to the thrust collar fixing spacer 7a. Extend more than ~ 7d width. Thereafter, the thrust collar fixing spacers 7a to 7d are fitted into the fixing groove 9 from the radial direction. The double-shaped thrust collar fixing spacers 7a to 7d fitted in the fixing groove 9 are fastened with bolts for each pair. The tensions 10a and 10b applied to the small gear shaft 4 are removed.

  In the fixed groove 9 portion of the small gear shaft 4 after the tension is removed, radial and axial preloads are generated on the thrust collar fixed spacers 7a and 7b. In this series of assembly, the squareness of both side surfaces of the fixing groove 9 and both side surfaces corresponding to the fitting portions of the thrust collar fixing spacers 7a to 7d to the fixing groove 9 is managed to a predetermined value. Thereby, the small gear shaft 4 is prevented from bending.

  In this embodiment, the thrust collars 6a and 6b are arranged on both sides of the small gear 3. However, the thrust collar fixing spacers 7a to 7d are formed directly on the side surface of the large gear 1 without providing the thrust collars 6a and 6b. The thrust bearings 8a and 8b can be brought into contact with each other. In this case, the number of parts can be reduced. Further, in this embodiment, the thrust collar fixing spacers 7a to 7d are formed in a substantially semicircular split shape, but since the mating surfaces of the thrust collar fixing spacers 7a to 7d extend in the axial direction, the radial direction toward the axial center The line may be inclined with respect to the straight line. For example, a tangential direction from the inner peripheral surface may be used as the mating surface.

  When the thrust collar fixing spacer acts as a thrust collar, both the surface facing the thrust collar fixing spacer and the thrust collar fixing spacer are conical surfaces and are in line contact via the oil film. When the mating surface of the thrust collar fixing spacer is formed in this way, the contact line can pass smoothly when the contact line moves near the joint of the thrust collar fixing spacer as the rotary shaft rotates. Furthermore, in this embodiment, the thrust collar fixing spacers 7a to 7d are split into two, but it goes without saying that the thrust collar fixing spacers 7a to 7d may be composed of three or more parts.

  In the embodiment shown in FIG. 1, another example in which the thrust collar fixing spacers 7a to 7d are fitted in the fixing groove 9 will be described below. This is an example in which the thrust collar fixing spacers 7 a to 7 d are shrink-fitted into the fixing groove 9. The dimensional relationship between the fixing groove 9 and the thrust collar fixing spacers 7a to 7d is the same as that of the embodiment shown in FIG.

  The small gear shaft 4 provided with the small gear 3 is set to a temperature higher than that of the thrust collar fixing spacers 7a and 7b, and the width of the fixing groove 9 is extended beyond the width of the thrust collar fixing spacers 7a and 7b. The thrust collar fixing spacers 7a to 7d are fitted into the fixing groove 9 from the radial direction. The thrust collar fixing spacers 7a to 7d are fastened with bolts for each pair. The small gear shaft 4 is cooled. As a result, radial and axial preloads are generated between the thrust collar fixing spacers 7 a to 7 d and the fixing groove 9.

  In each of the above embodiments, the rotating shaft and the large gear are separated, but a large gear integrated with the rotating shaft may be used. In this case, bending of the shaft can be reduced. Further, although the small gear and the rotation shaft are integrally formed, the small gear may be fixed to the rotation shaft using a key or the like. Further, when the centrifugal load is relatively small, the thrust collar may be fixed to the shaft with a key or the like, and the axial preload may be applied to the thrust collar fixing spacer by the above-described methods.

It is a principal part perspective view of one Example of the turbo compressor which concerns on this invention. It is a perspective view of the thrust bearing part of the turbo compressor shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Large gear, 2 ... Large gear shaft (drive shaft), 3 ... Small gear, 4 ... Small gear shaft (rotation driven shaft),
5a, 5b ... impeller, 6a, 6b ... thrust collar, 7a, 7b ... thrust collar fixing spacer (thrust collar fixing means), 8a, 8b ... sliding surface (thrust bearing), 9 ... fixing groove, 10a, 10b ... tension.

Claims (8)

  In the turbo compressor that transmits the power of the driving machine to the impeller through the speed increaser, the speed increaser includes a large gear formed on a helical tooth and thrust bearing surfaces formed on both side surfaces of the large gear. A rotary drive shaft having a gear, a small gear formed on a helical gear meshing with the large gear, a thrust collar disposed on both side surfaces of the small gear, and a thrust collar fixed disposed on a side opposite to the small gear of the thrust collar The thrust collar is press-fitted into the rotary driven shaft, and a ring-shaped groove is formed in the rotary driven shaft, and the thrust collar fixing means is connected to the ring-shaped shaft. The width of the thrust collar fixing means before being fitted into the groove is formed wider than the width of the groove. The thrust collar fixing means is fitted into the groove by extending the rotary driven shaft and preloaded. From Turbo compressor, characterized in that is.   The thrust collar fixing means is formed in a split shape, and when the thrust collar fixing means is fitted in the groove, the rotating driven shaft is heated or stretched by pulling from both ends of the rotating driven shaft. The turbo compressor according to claim 1.   A bearing device used for a turbo compressor, which is a thrust bearing formed on both side surfaces of a large gear constituting a speed increasing gear, a pair of thrust collars that slide on the thrust bearing via an oil film, and the thrust Holding a collar on a rotary driven shaft provided with a small gear, and having a pair of thrust collar fixing means disposed on the opposite side of the thrust collar, the thrust collar being press-fitted into the rotary driven shaft, A ring-shaped groove is formed on the driven shaft, and the width of the thrust collar fixing means before the thrust collar fixing means is fitted into the ring-shaped groove is wider than the width of the groove. And a bearing device characterized in that a preload is generated by extending a rotary driven shaft and fitting a thrust collar fixing means into the groove.   The thrust collar fixing means is formed in a split shape, and the width before the thrust collar fixing means is fitted into the groove formed on the rotary driven shaft is wider than the width of the groove. The thrust bearing device according to claim 3. In a method of assembling a thrust bearing device having a pair of thrust collars that slide through an oil film on thrust bearings formed on both sides of a large gear,
The thrust collar is press-fitted into a rotary driven shaft provided with a small gear that meshes with a large gear, and a thrust collar fixing means for pressing the thrust collar from the axial direction is inserted into a groove formed in the rotary driven shaft in the axial direction. A method for assembling a thrust bearing device, wherein the thrust bearing device is fitted.   When the thrust collar fixing means is fitted to the rotary driven shaft with a margin in the axial direction, the rotary driven shaft is heated and the width of the groove formed on the shaft is set to the width of the thrust collar fixing means. 6. The method of assembling a thrust bearing device according to claim 5, wherein the thrust bearing device is further spread out.   When the thrust collar fixing means is fitted to the rotary driven shaft with an interference in the axial direction, the rotary driven shaft is pulled in the axial direction, and the width of the groove formed on the shaft is set to the thrust collar fixing means. The method for assembling the thrust bearing device according to claim 5, wherein the method is wider than the width of the thrust bearing device. The thrust collar fixing means is formed in a split shape, and when the thrust collar fixing means is fitted to the rotary driven shaft with an allowance in the axial direction, the split collar fixing means is split. 6. The method for assembling a thrust bearing device according to claim 5, wherein the shaft is fitted in the direction from the outer diameter side to the inner diameter side of the rotary driven shaft, and the fitted thrust collar fixing means is fastened using fastening means.

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