JPH0475441A - Rotor wedge of electric rotating machine - Google Patents

Abstract

PURPOSE:To realize uniform stress distribution and to eliminate local metal fatigue by applying a coating layer of solid state film lubricant onto the surface of a wedge. CONSTITUTION:A coating layer 16 of solid state film lubricant, composed of solid state lubricant such as ground graphite or molybdenum disulfide kneaded with adhesive, is applied onto the surface of a wedge 8. Consequently, a wedge exhibiting a low frictional coefficient even for high surface pressure is obtained, damage due to fretting can be prevented and the reliability can be improved.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a rotor wedge for a rotating electric machine, and in particular, the present invention relates to a rotor wedge for a rotating electric machine, and in particular, by inserting the wedge into a wedge groove on the outer diameter of a slot provided on the outer periphery of the rotor. The present invention relates to a rotor wedge suitable for a rotating electric machine that fixes a coil or an output lead in a slot.

(Prior Art) In a rotating electric machine having a cylindrical rotor, the rotor coil and lead are housed in slots of the rotor, and the outer circumferential side of the rotor is restrained by a wedge in order to prevent them from flying out due to centrifugal force. FIG. 5 shows a longitudinal cross-sectional view of the iron core of the rotor of a turbine generator, and the rotor (1) is provided with slots (2) in a number corresponding to the number of rotor coils via teeth (la). . A wedge groove (3) into which a wedge can be inserted is formed on the outer peripheral side of the slot.

Figure 6 shows the coil and wedge inserted into this slot, and the rotor coil (4) (6 turns in the figure) is insulated from the rotor (1) by insulators (5) and (6). Between each turn of the rotor coil (4) is an interlayer insulator (
7) are mutually insulated.

When such a rotor rotates, for example, the number of revolutions is 3600.
In a typical large turbine generator, a centrifugal force of up to about 8,000 G (8,000 times the acceleration of gravity) acts every minute.

Therefore, the wedge (8) receives centrifugal force loads from the rotor coil, the insulator, and the wedge itself with respect to the rotor (1) at the shoulder portion (9).

Note that this wedge (8) is divided in the longitudinal direction of the rotor core of the generator, and a typical shape thereof is shown in FIG.

(Problem to be solved by the invention) As mentioned above, since it is subjected to centrifugal force of up to 8000G,
Significant stresses are created in the wedge (8). Figures 8 and 9
The figure shows an example of stress analysis performed using the finite element method near the shoulder corner (1o) of such a wedge.
0), stress concentration occurs and the maximum stress point occurs as shown in the figure. Therefore, the material of the wedge must be selected to sufficiently withstand this stress. Moreover, this stress acts repeatedly each time the rotor is started and stopped. On the other hand, as shown in FIG. 10, the rotor of a rotating electrical machine undergoes static deflection due to the weight of the rotor shaft (11) itself. For example, when the wedge (8) is positioned perpendicular to gravity, the wedge (8) is forcibly deformed by the deflection of the rotor shaft (11). On the other hand, the wedge itself has bending rigidity, and a reaction force is generated near the axial end of the wedge against forced deformation. Arrows (12) and (13) in the figure indicate the direction in which the reaction force is generated. Now, this reaction force acts in the tangential direction, or since the contact part between the wedge and the shaft nice (1a) side is tapered, the reaction force (13) generated in the tangential direction acts on the wedge as shown in Figure 11. Force in the direction perpendicular to the shoulder taper part (I
4) and a force (15) in the direction perpendicular to it. This force (14) acts as a bending stress on the shoulder corner (10) of the wedge.

Therefore, in addition to the stress due to the centrifugal force mentioned above (stress distributed as shown in FIG. 9), stress is also generated due to static deflection of the rotor shaft (11).

This stress increases closer to the end of the wedge. Furthermore, due to the end of the wedge coming into contact with the shaft teeth (la), there is a so-called edge effect, and the stress becomes higher. In other words, the stress generated in the wedge varies as the rotor rotates, so for example, for a rotor rotating at 3600 per minute,
After just 2,780 continuous hours (116 days) of operation, there are 107 cycles of fluctuating stress. This is the number of times the metal material reaches its fatigue limit.

Figure 12 shows how the stress fluctuations that act on the shoulder corner (10) of the wedge act in this way.In addition to the stress fluctuations caused by starting and stopping the rotor, there are also stress fluctuations due to high cycles due to rotation. It shows how it works. Further, FIG. 13 shows the distribution of stress in the stacking direction occurring at the shoulder corner portion (10) of the wedge using arrows and curves, indicating that the stress is higher at the wedge end. This is because, as mentioned above, the effect of bending due to static deflection of the rotor is greater at the end, and the edge effect due to contact is also added.

In this way, when the contact surface pressure at the abutting part between the wedge and the wedge groove increases, fretting occurs at the wedge shoulder, even if the wedge has sufficient fatigue strength based on average stress calculations. A large number of microcracks are generated along with the bit in the contact area, which can reduce the fatigue strength of normal materials by as much as 70 to 80%.

Furthermore, the wedge may be damaged and scattered due to centrifugal force. In such a case, it will be a fatal accident for the rotating electric machine. Specifically, damage to the stationary side (stator of the rotating electric machine) caused by flying objects and damage to other parts due to increased unbalanced vibration of the rotor occur, resulting in loss of function of the rotating electric machine.

The purpose of the present invention is to alleviate the stress at the wedge end.
It is an object of the present invention to provide a rotor wedge for a rotating electric machine which has uniform stress distribution and does not suffer from partial metal fatigue.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above-mentioned problems, as a first means in the present invention, a coating layer of a solid film lubricant is provided on the surface of the wedge.

The second method is 1. The cross section of the wedge has a convex shape in which the shoulder portion of the wedge is in contact with the wedge groove, and a relief portion toward the upper portion of the wedge is provided on an extension of the shoulder portion at least at one end of the wedge.

(Function) According to the first means, fretting becomes less likely to occur by reducing the friction coefficient of the contact surface between the wedge and the wedge groove.

According to the second means, by alleviating the stress concentration at the wedge end by the relief part, even if the stress distribution in the longitudinal direction of the wedge increases the stress at the wedge end due to rotor deflection or edge effect. At the maximum stress, the stress does not increase at the wedge end, and a nearly uniform stress distribution can be achieved.

Therefore, both the first and second means can locally prevent damage to the wedge due to fatigue, and provide a highly reliable rotor wedge for a rotating electric machine.

(Examples) Example 1 A first example of the present invention will be described below with reference to FIG. 1. In this Example 1, the surface of the wedge (8) is coated with a solid lubricant such as crushed graphite or molybdenum disulfide mixed with an adhesive, and then dried to form a solid film lubricant coating layer (1B) ( 1st
Although the figure shows diagonal lines, the cross section is not shown). The rest is the same as the conventional example shown in FIGS. 5 to 7.

By providing a coating layer of a solid film lubricant on the surface of the wedge (8) in this way, a wedge with a low coefficient of friction can be created even under high surface pressure, and damage caused by fretting can be prevented. Its reliability can be improved.

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIG. In this second embodiment, the cross section of the wedge (8) has a convex shape with a tapered shoulder (9) abutting the wedge groove;
Both ends of this wedge (8) (if the load under the wedge is extremely biased to one side, only one end on the side with the larger load may be used)
A relief part (17) extending linearly is provided on the extension of the shoulder part. This is done by widening the taper at the end of the wedge at the same angle as the taper angle of the shoulder (9) of the wedge, thereby eliminating the wedge groove corner where stress concentration occurs. The rest is the same as the conventional example shown in FIGS. 5 to 7.

In this way, as shown by the arrow and curve in Figure 3,
Contrary to the conventional example shown in FIG. 18, the stress distribution decreases at the ends. This is because the tapered relief part (17) is provided at the end of the wedge (8) according to the second embodiment.
This is because the stress concentration is eliminated and the maximum stress is reduced, and the stress generated in the wedge can be averaged to prevent damage due to local metal fatigue, and its reliability can be improved.

Example 3 ′! In the third embodiment shown in Fig. J4, a relief portion (17) is provided in an arc shape extending from the shoulder portion (9) toward the wedge portion.

The rest is the same as in Example 2.

Even in this case, the same effects as in the second embodiment can be obtained.

[Effects of the Invention] As explained above, according to the present invention, the stress distribution is made uniform by relaxing the stress at the wedge end, and a highly reliable rotating electrical machine that does not suffer from local metal fatigue can be achieved. A rotor wedge can be provided.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a first embodiment of a rotor wedge for a rotating electric machine according to the present invention, FIG. 2 is a perspective view showing a second embodiment, and FIG.
The figure is an explanatory view showing the longitudinal distribution of stress occurring at the shoulder corner of the rotor wedge in the embodiment shown in Fig. 2, Fig. 4 is a perspective view showing the third embodiment, and Fig. 5 is a conventional example and the present invention. FIG. 6 is a cross-sectional view showing a common part of the shaft to which each of the embodiments is applied, FIG. 6 is a cross-sectional view showing the structure inside the slot of FIG. 5, FIG. 7 is a perspective view showing the wedge of the conventional example, and FIG. The figure is a stress analysis model diagram of the shoulder corner of the rotor wedge, which is common to the conventional example and each embodiment of the present invention.
Fig. 9 is a contour diagram of the stress in Fig. 8, Fig. 10 is an explanatory diagram showing the force acting on the rotor wedge due to static deflection of the rotor, and Fig. 11 is a vector diagram showing an exploded reaction force in Fig. 1D. , FIG. 12 is an explanatory diagram showing the variation of stress generated at the rotor wedge shoulder corner according to the operating pattern of the rotating electrical machine, and FIG. 13 is a longitudinal direction of the stress generated at the rotor wedge shoulder corner shown in FIG. 7 in the conventional example. It is an explanatory diagram showing distribution. 2...Slot, 3...Wedge groove, 4...Rotor coil, 8...Wedge, 9...Shoulder part,
16... Coating layer, 17... Relief part. Agent: Patent Attorney Nori Ogo

Claims (2)

[Claims] (1) Rotation of a structure in which a slot extending in the axial direction is dug on the outer circumference of the rotor, a rotor coil or lead lead is inserted into the slot, and a wedge is inserted into the outer circumference to fix the rotor coil or lead lead in the slot. A rotor wedge for a rotating electrical machine, characterized in that a coating layer of a solid film lubricant is provided on the surface of the wedge. (2) Rotation of a structure in which a slot extending in the axial direction is dug on the outer circumference of the rotor, a rotor coil or lead lead is inserted into the slot, and a wedge is inserted into the outer periphery to fix the rotor coil or lead lead in the slot. In electrical machinery, the cross section of the wedge is shaped like a convex shape with a tapered shoulder abutting the wedge groove, and at least one end of the wedge is provided with a relief section toward the upper part of the wedge on the extension of the taper of the shoulder. A rotor wedge for a rotating electrical machine featuring: