JPH05118201A - Rotor for high speed rotation - Google Patents

Abstract

PURPOSE:To rise the critical speed of an overhang part, simplify the vibration property of a rotor at a rated speed and facilitate its balancing. CONSTITUTION:The overhang part 9 of a rotor 1 is ended by a thrust bearing collar 10 and a shaft part does not exist in the outside of this collar 10. The weight of this part is lightened by this structure. A center hole 13 is arranged on the shaft part of the overhang part 9 so as to be hollow and then the weight/ the section bend rigidity ratio of this part can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor for high speed rotation of a steam turbine, a gas turbine, an axial compressor or the like, and more particularly to a rotor for high speed rotation having a thrust bearing collar in an overhang portion outside a bearing span.

[0002]

2. Description of the Related Art For example, in a steam turbine, when the capacity is small, it is necessary to reduce the height of the blade. However, if the height of the blade is lowered, the ratio of the gap between the rotating part and the stationary part to the height of the blade becomes large, so the amount of steam that leaks through the above-mentioned gap is larger than the amount of steam that works through the blade. Efficiency increases.

To increase the height of the blade in order to prevent this, it is necessary to reduce the average diameter of the blade. However, if the average diameter of the blades is reduced, the peripheral speed of the blades decreases at the same number of revolutions, so the heat drop that can be efficiently digested by a single stage blade is reduced.

In order to prevent this, it is necessary to increase the rotation speed so that the peripheral speed of the blade does not decrease. For this purpose, high speed rotation is adopted. FIG. 3 shows an example of a conventional high-speed turbine rotor that is rotated at such a high speed.

This rotor 1 has a rated speed of 100,000 r
a pm turbine rotor having front and rear bearing journals 2 and 3 at its front and rear ends, respectively, and a first stage blade 4, between these bearing journals 2, 3.
The second stage blade 5, the third stage blade 6, the fourth stage blade 7 and the fifth stage blade 8 are provided, and the overhang portion 9 provided on the front bearing journal 2 side has the thrust bearing collar 10. A shaft end portion 11 extends outside the thrust bearing collar 10. In addition, 12 shows a coupling.

[0006]

When high-speed rotation is adopted for a rotor of a steam turbine or the like, however, many critical speeds of the rotor come out up to the rated speed. In particular, as shown in FIG. 3, when the thrust bearing collar 10 is provided in the overhang portion 9 outside the bearing span of the rotor 1, the critical speed of this portion becomes lower than the rated speed. That is, when the thrust bearing is provided in the overhang portion 9, it is necessary to reduce the shaft diameter of the thrust pad portion, so that the rigidity of this portion is reduced and the critical speed is reduced.

When the bearing spans of the rotor are flexible and the critical speed of the overhang portion becomes lower than the rated speed as described above, the vibration characteristics at the rated speed become complicated and balancing becomes difficult.

The present invention has been made in order to solve the problems of the prior art, and can increase the critical speed of the overhang portion, thereby simplifying the vibration characteristics of the rotor at the rated speed and facilitating balancing. An object is to provide a rotor for high speed rotation.

[0009]

In order to solve the above-mentioned problems, the present invention relates to a rotor for high speed rotation having a thrust bearing collar in an overhang portion outside a bearing span, and a shaft portion outside the thrust bearing collar. In addition to the above structure, the shaft portion of the overhang portion is hollow.

[0010]

According to the above means, since the rotor ends at the portion of the thrust bearing collar and there is no shaft portion extending outside the thrust bearing collar, the weight of this portion is reduced and the critical speed of the overhang portion is reduced. Go up. Further, by making the shaft portion of the overhang portion hollow, the weight / cross sectional bending rigidity ratio of this portion is reduced, and the critical speed of the overhang portion is increased. It should be noted that these do not impair the function of the thrust bearing.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. FIG. 1 is a view showing a rotor for high speed rotation according to the present embodiment, and FIG. 2 is an enlarged cross-sectional view of a portion A of FIG. In these figures, the same parts as those shown in FIG. 3 are designated by the same reference numerals, and duplicated description will be omitted.

According to the present embodiment, as shown in FIGS. 1 and 2, the rotor 1 for high speed rotation has an overhang portion 9 which ends in a thrust bearing collar 10 and an axial portion outside the thrust bearing collar 10. It has no structure. In other words, the shaft end portion 1 of the conventional rotor shown in FIG.
It has a structure in which 1 is cut and lost. Then, a central hole 13 extending from the center of the end face of the thrust bearing collar 10 is bored in the shaft portion of the overhang portion 9 to make the shaft portion of the overhang portion 9 hollow.

According to the construction described above, the rotor 1 for high speed rotation ends at the portion of the thrust bearing collar 10.
Since there is no shaft portion extending outside the thrust bearing collar 10, the weight of this portion is reduced and the critical speed of the overhang portion 9 is increased. Further, since the shaft portion of this overhang portion 9 is hollow, the weight of this portion /
The cross-sectional bending rigidity ratio decreases, and the critical speed of the overhang portion 9 increases. And, these do not impair the function of the thrust bearing.

[0014]

As described above, according to the present invention, in the rotor for high speed rotation having the thrust bearing collar on the overhang portion on the outer side of the bearing span, there is no shaft portion outside the thrust bearing collar. With
By making the shaft portion of the overhang portion hollow, the critical speed of the overhang portion increases and the vibration characteristics of the rotor at the rated speed are simplified, so that balancing is facilitated. On the other hand, the function of the thrust bearing is not impaired. Therefore, these can improve the reliability of the rotor for high speed rotation.

[Brief description of drawings]

FIG. 1 is a diagram showing a rotor for high speed rotation according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a portion A of FIG.

FIG. 3 is a diagram showing a conventional rotor for high speed rotation.

[Explanation of symbols]

 1 rotor 2 front bearing journal 3 rear bearing journal 4 first stage blade 5 second stage blade 6 third stage blade 7 fourth stage blade 8 fifth stage blade 9 overhang portion 10 thrust bearing collar 12 coupling 13 center hole

Claims (1)

[Claims] 1. A high-speed rotor having a thrust bearing collar in an overhang portion outside a bearing span,
A rotor for high-speed rotation, characterized by having a structure in which there is no shaft portion outside the thrust bearing collar and hollowing the shaft portion of the overhang portion.