JP4946114B2 - Rotating machine - Google Patents

Description

  The present invention relates to a rotating machine having an impeller that rotates at high speed, such as a turbine and a compressor.

  One compressor that rotates a rotating machine, for example, an impeller at high speed, is a geared compressor. The geared compressor is briefly described with reference to FIG.

  In FIG. 2, 1 is a shaft box, and a drive shaft 2 and an impeller shaft 3 are rotatably provided on the shaft box 1 via bearings 4 and 5, respectively. The drive shaft 2 and the impeller shaft 3 are driven. It is connected via a gear 6 and a driven gear 7.

  Impellers 11 and 12 are fitted to both end portions 8 and 9 of the impeller shaft 3 by shrinkage fitting, and the impellers 11 and 12 are respectively stored in housings 13 and 14 attached to the axle box 1. Between the housings 13 and 14 and the impeller shaft 3, shaft seal devices 15 and 16 are provided.

  When the drive shaft 2 is rotated by a drive source (not shown) such as a motor, the impeller shaft 3 is rotated at an increased speed via the drive gear 6 and the driven gear 7, and the impeller 11, The impeller 12 is rotated at high speed.

  Due to the rotation of the impeller 11, a fluid to be compressed such as air is sucked from the suction port 17 of the housing 13, and the compressed fluid is discharged from the discharge port (not shown) through the annular channel 18. Similarly, due to the rotation of the impeller 12, the fluid to be compressed is sucked from the suction port 19 of the housing 14, and the compressed fluid is discharged from the discharge port (not shown) through the annular channel 21.

  In a rotating machine, the critical speed (natural frequency) of the rotating part needs to deviate from the rotational speed (rotational frequency) during steady operation in order to avoid resonance. For example, it is desirable that it is higher when the dangerous speed is higher than the driving speed, and lower when the dangerous speed is lower than the driving speed.

  In the compressor described above, the impellers 11 and 12 having a heavy weight are attached to the shaft end portions 8 and 9 that protrude in a cantilever shape and have a small diameter, and the critical speed of the rotating portion is determined by the shaft end portions 8 and 9. 9 greatly depends on the rigidity.

  In general, when designing a compressor, the specifications of the impeller and the rotational speed of the impeller are determined so as to satisfy the required performance, and further specifications of other parts, for example, the shaft diameter of the impeller shaft 3 are determined. Etc. are determined. After the specifications of each part are determined, the critical speed of the rotating part is confirmed by simulation.

  For example, as a result of simulation, if the critical speed of the rotating part matches the steady rotation during operation or is close to the side larger than the steady rotation and there is a possibility of resonance, the dangerous speed of the rotating part is large. Measures are taken to increase the rigidity of the rotating part. As a simple measure, the shaft end portions 8 and 9 are thickened to increase the rigidity of the impeller shaft 3.

  However, when the shaft diameter is increased, the shaft end portions 8 and 9 are insufficient when the necessary wall thickness for obtaining a predetermined fitting force of the fitting portions of the impellers 11 and 12 is insufficient (particularly the tip portion in the impeller axial direction). The shaft diameter is limited. If the shaft diameters of the shaft end portions 8 and 9 cannot be increased as much as necessary, the diameter of the impeller shaft 3 inside the fitting portion must be changed, and the shaft end portion 8 and the support portion of the impeller shaft 3 are rotated. A review of the entire machine is required. For this reason, it takes a lot of time and effort to determine the final specifications of each part.

JP 2001-173594 A

JP 2001-173597 A

  In view of such circumstances, the present invention makes it possible to change the rigidity of the rotating part so that the critical speed of the rotating part does not coincide with or be close to the steady rotation during operation, and the rotation without reexamination of the entire rotating machine. The machine can be manufactured.

  The present invention includes an impeller shaft that is rotated in a steady state and an impeller that is fitted to a shaft end portion of the impeller shaft, and the fitting portion of the shaft end portion and the impeller includes a tight fitting portion and a gap. Torque transmission between the impeller shaft and the impeller is performed by the interference fitting portion, and the shaft shape of the gap fitting portion of the shaft end portion causes the critical speed of the rotating portion to resonate with steady rotation. This relates to a rotating machine set to be suppressed.

  According to the present invention, in a rotating machine including an impeller shaft that is normally rotated and an impeller that is fitted to a shaft end portion of the impeller shaft, the fitting portion of the shaft end portion and the impeller includes: The interference fitting portion and the gap fitting portion, and the interference fitting portion is set in a fitting state so that torque is transmitted between the impeller shaft and the impeller, and simulates the critical speed of the rotating portion, and the shaft The shaft shape of the gap fitting portion at the end portion is related to a rotating machine in which the critical speed is set to have such rigidity that suppresses resonance during steady rotation.

  The present invention also relates to a rotating machine in which the gap fitting portion of the shaft end portion has a larger diameter than the interference fitting portion, and the gap fitting portion of the shaft end portion gradually increases in diameter from the interference fitting portion. This relates to a rotating machine having a tapered shape.

  Further, the present invention relates to a rotary machine in which the gap fitting portion of the shaft end portion has a diameter smaller than that of the interference fitting portion, and the gap fitting portion of the shaft end portion is gradually narrower than the interference fitting portion. The present invention relates to a rotating machine having a tapered shape as a diameter.

  According to the present invention, it includes an impeller shaft that rotates normally and an impeller that is fitted to the shaft end portion of the impeller shaft, and the fitting portion of the shaft end portion and the impeller is an interference fitting portion. And the clearance fitting portion transmits torque between the impeller shaft and the impeller, and the shaft shape of the gap fitting portion of the shaft end portion is such that the critical speed of the rotating portion is a steady rotation. Since it is set to suppress the resonance, the resonance can be suppressed with a simple structure, and the change of the shaft end part to suppress the resonance does not require a review of the entire rotating machine, so it can be easily performed in a short time, Production costs can be reduced.

  Further, according to the present invention, in a rotating machine including an impeller shaft that is rotated in a steady state and an impeller that is fitted to the shaft end of the impeller shaft, the shaft end and the impeller are fitted together. The part has a tight fitting part and a gap fitting part, and the tight fitting part is set in a fitting state so that torque is transmitted between the impeller shaft and the impeller, and simulates the critical speed of the rotating part, The shaft shape of the gap fitting portion at the end of the shaft is set so that the critical speed has such rigidity as to suppress resonance during steady rotation, so that resonance can be suppressed with a simple structure and resonance can be suppressed. The change of the shaft end for this purpose does not require a review of the entire rotating machine, so it can be done easily in a short time and exhibits excellent effects such as reduced production costs.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a view showing a part of a rotating part of a rotating machine according to the present invention.

  In FIG. 1, the same components as those shown in FIG. In the figure, an arrow A indicates the bearing center position.

  A shaft end 8 having a small diameter is formed at the end of the impeller shaft 3, and the shaft end 8 has a fitting portion 8a into which the impeller 11 is shrink-fitted and a large diameter with respect to the fitting portion 8a. And a shaft end reinforcing portion 8b. The fitting hole 23 formed in the impeller 11 is a stepped hole including a fitting hole 23a into which the fitting portion 8a is fitted and a play hole 23b into which the shaft end reinforcing portion 8b is fitted. ing.

  The impeller 11 is fixed to the shaft end 8 by shrink fitting, and a nut 24 is screwed onto the tip of the shaft end 8 and attached.

  The shaft diameter of the fitting portion 8a is set so as to have a thickness required when the fitting hole 23a portion is shrink-fitted, and the fitting shaft length is determined by the fixing force generated by shrink fitting. It is set to be sufficient for torque transmission between the wheel 11 and the impeller shaft 3. Further, the shaft end reinforcing portion 8b and the play hole 23b have a sufficiently large clearance fit, and the shaft end reinforcing portion is used when the fitting portion 8a and the fitting hole 23a are shrink-fitted. 8b and the play hole 23b do not interfere with each other.

  The portion where the play hole 23b is formed is a portion where the centrifugal force of the impeller 11 acts greatly when the impeller 11 is rotated at a high speed, and the play hole 23b is caused by the action of the centrifugal force. Expands. In the portion where the play hole 23b is formed, even if the shaft end reinforcing portion 8b portion is shrink-fitted into the play hole 23b, the effect of shrink-fitting is not exhibited due to expansion by centrifugal force. Therefore, even if the shaft end reinforcing portion 8b is fitted into the play hole 23b, the fixing force of the impeller 11 is not affected and the fixing force is not insufficient.

  As described above, the portion of the impeller shaft 3 that has the greatest influence on the critical speed is the shaft end portion 8 to which the impeller 11 is attached and the shaft diameter is reduced. Increasing the rigidity of the end 8 is effective in increasing the rigidity of the impeller shaft 3.

  By increasing the diameter of the shaft end reinforcing portion 8b, the rigidity of the shaft end portion 8 can be increased without affecting torque transmission, and the critical speed of the impeller shaft 3 can be increased. Moreover, it is not necessary to change anything about the shaft diameter of the impeller shaft 3 and the other portions such as the impeller 11 to increase the diameter of the shaft end reinforcing portion 8b. Therefore, the rigidity of the impeller shaft 3 can be increased without changing the performance of the rotating machine.

  Further, as an example of the procedure for determining the diameter of the shaft end reinforcing portion 8b, the specifications, steady rotational speed, bearings, etc. of the impeller 11 are determined so as to satisfy the performance required as a rotating machine. Then, the diameter of the shaft end reinforcing portion 8b is provisionally determined, and a simulation is performed when the rotating portion is steadily rotated to obtain the critical speed of the rotating portion.

  As a result of the simulation, if the critical speed is equal to or close to the steady rotational speed and there is a possibility that the rotating part may resonate, the diameter of the shaft end reinforcing part 8b is increased or decreased, Alternatively, the shape is changed and the rigidity of the shaft end 8 is changed so that the critical speed of the impeller shaft 3 does not coincide with the steady rotation, or is separated from the steady rotation.

  After changing the diameter and shape of the shaft end 8, it is confirmed again by simulation whether the rotating part does not resonate at steady rotation.

  Note that the change of the shaft end reinforcing portion 8b does not affect the support portion of the impeller shaft 3 and the like, and therefore, it is not necessary to review the entire rotating machine, and the shaft end reinforcing portion 8b is changed. Is simple.

  Further, the shape of the shaft end reinforcing portion 8b only needs to be changed in rigidity so that the critical speed of the shaft deviates from the operating speed. When the critical speed of the shaft is higher than the operating speed, the diameter gradually increases from the tip side. When the critical speed of the shaft is lower than the operating rotational speed, the shaft end reinforcing portion 8b may have a small diameter so that the critical speed of the shaft is reduced, or from the tip side. It is good also as a taper shape used as a gradually small diameter. The shaft end reinforcing portion 8b may not be in contact with the play hole 23b, and accuracy is not required for processing and finishing of the shaft end reinforcing portion 8b and the play hole 23b.

It is a side view which shows the principal part of the impeller shaft in embodiment of this invention. It is the schematic which shows an example of a rotary machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft box 3 Impeller shaft 5 Bearing 6 Drive gear 7 Driven gear 8 Shaft end part 8a Fitting part 8b Shaft end reinforcement part 11 Impeller 23 Fitting hole 23a Fitting hole 23b Play hole

Claims (4)

An impeller shaft that is supported and steadily rotated via a bearing , and an impeller that is fitted to a shaft end portion that protrudes from the bearing of the impeller shaft, the fitting portion of the shaft end portion and the impeller Has a tight fitting portion formed on the tip side and a gap fitting portion formed on the bearing side, and torque transmission between the impeller shaft and the impeller is performed by the tight fitting portion, and the shaft end portion is rotary machine, characterized in that the clearance fit section the shaft shaped as clamping fit rigid than portion is increased is formed, the critical speed of the rotating section is set so as to suppress the resonance of the steady rotation. In a rotary machine comprising an impeller shaft that is supported and steadily rotated via a bearing , and an impeller that is fitted to a shaft end portion that protrudes from the bearing of the impeller shaft, the shaft end portion and the blade The fitting portion of the vehicle has a tight fitting portion and a gap fitting portion, and the fitting state is set so that torque is transmitted between the impeller shaft and the impeller, and the critical speed of the rotating portion is set. simulating the said shaft end shaft shaped as a clearance fit portion increases rigidity than the clamping fitting portion is formed, the critical speed of the rotating section is set to suppress like the resonance with the steady rotation A rotating machine characterized by that.   The rotary machine according to claim 1 or 2, wherein the gap fitting portion at the shaft end portion has a larger diameter than the interference fitting portion.   The rotary machine according to claim 1 or 2, wherein the gap fitting portion at the shaft end portion has a tapered shape that gradually increases in diameter from the interference fitting portion.

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