JPH0429304B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a rotor with a plurality of slots provided in the axial direction on the outer peripheral surface of the rotor, a coil and a plurality of wedges inserted into the lower and upper parts of these slots, respectively. This invention relates to a turbine generator rotor in which a coil is fixed in a slot by a wedge.

[Conventional technology]

As shown in FIGS. 1 to 3, a conventional rotor of this type has a large number of slots 3 in the axial direction in a rotor core 2 formed integrally with a shaft 1, and a coil 4 in the lower part of each of these slots 3. In addition to inserting
It has a structure in which a plurality of wedges 5A are inserted into the upper part of the slot 3 so that they are positioned on top of the coil 4 via a spacer 6, and the wedges 5A cause the coil 4 to be pushed into the slot 3 by the centrifugal force caused by the rotation of the rotor. It prevents you from escaping from within.

[Problem to be solved by the invention]

The wedge 5A may be formed in various shapes, but generally it is formed in a tabtail shape as shown in FIGS. 2 and 3, and other shapes such as a T-shape and a Christmas tree shape are also used. Since a plurality of these wedges 5A are inserted into the slot 3, a contact end 8 is always formed at the contact surface 7' between the wedge 5A and the slot 33, where the end surfaces of the adjacent wedges 5A touch each other. Not only is surface pressure concentrated on this contact end 8 due to centrifugal force, but also when the rotor core 2 rotates with a curvature r due to its own weight or bending vibration, as shown in FIG. (rotor core 2) and wedge 5
Relative slip ±δ occurs between A and A. For this reason, large tensile and compressive stresses are concentrated in the sliding direction on the rotor core 2 side of the contact end 8, which has the drawback of causing fretting damage and making fatigue cracks more likely to occur.

In Fig. 4, if the radius of the rotor is r ₀ and the length of the wedge 5A is l, the rotor core 2 is at the upper point A.
When reaching the lower point B, the wedge 5A expands and contracts by δ (=1/2r ₀ /6l) at a position corresponding to the end of the wedge, but does not expand or contract because the wedge 5A is divided in the longitudinal direction. Therefore, a relative slip 2δ (=r ₀ /rl) occurs at the contact end 8 between the wedge 5A and the rotor core 2 for each rotation of the rotor.

As mentioned above, the contact pressure is concentrated at the contact end 8, and it is generally known that if a contact surface with high contact pressure is accompanied by relative slip, the fatigue strength will be significantly reduced due to fretting damage, which is a problem in terms of strength. It is.
The surface pressure distribution on the contact surface 7' between the rotor core 2 and the wedge 5A is as shown in FIG. 5, and it is clear from this figure that the surface pressure rapidly increases at the contact end 8. If the high surface pressure ends undergo relative sliding, a large tensile or compressive stress will be concentrated on the contact end 8 on the rotor core 2 side each time the wedge 5A relative slips, as shown in FIG. Recognize. The relationship between the contact pressure and the fretting fatigue strength is shown in Figure 7. This figure shows that the contact pressure has a great effect on the fretting fatigue strength, and when the contact pressure decreases to a certain extent, the fatigue strength decreases. It can be seen that the strength decreases rapidly and the strength improves.

In Utility Model Application Publication No. 57-27838, slits are provided in the rotor teeth between the body grooves to separate them in the axial direction. Techniques are disclosed to alleviate the resulting axial stresses. However, in this technique, no consideration was given to concentration of pressure on the contact surface between the rotor teeth and the wedges.

Furthermore, Japanese Patent Application Laid-Open No. 57-135647 discloses a technique in which the contact area between the wedge and the rotor is reduced to reduce the amount of relative slip.
By reducing the contact area, the contact surface pressure can be reduced by
The problem was that it became more expensive.

In view of the above, the present invention alleviates the concentration of surface pressure at the contact surface between the slot and adjacent wedge ends inserted into the slot of the rotor core, and prevents the occurrence of fretting damage due to bending deflection of the rotor. The object of the present invention is to provide a turbine generator rotor with high fatigue strength.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a plurality of slots in the axial direction on the outer peripheral surface of the rotor, and coils are arranged in the lower part of these slots and adjacent to each other in the axial direction in the upper part. In a turbine generator rotor formed by inserting a plurality of wedges, at least an operating point is provided at a position facing the gap formed between the axial end faces of adjacent wedges on the slot surface that contacts the wedges. A groove in which an opening with a width larger than the maximum width between the axial end faces of the wedges, which is generated due to the deflection of the rotor, is faced between the ends of the wedge is formed so that the front ends intersect with the slot surfaces. It is formed along the intersection line of the
The position is a position where the end face in the axial direction of the wedge remains within the opening of the groove even if the end face in the axial direction moves relative to the slot face due to the difference between the deflection of the rotor and the deflection of the wedge during operation. It is characterized by:

[Function and Examples of the Invention]

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

The embodiment shown in FIG.
A groove 13 for stress relaxation is provided in the portion in contact with the wedge to prevent concentration of tensile and compressive stress in the sliding direction at the contact end due to relative sliding between the wedge and the slot 3 (rotor core 2). The state of contact between the wedge and the slot (rotor core 2) at the groove 13 is as shown in FIG.
It can be seen that the groove 13 is divided into two places at both ends.

In the above embodiment, both end surfaces 9 of adjacent wedges 5
are in close contact with each other, but when both end surfaces 9 of adjacent wedges 5 are separated by a distance Δl as shown in FIG. 10, the width of the groove 13' may be made sufficiently longer than Δl.

FIG. 11 shows the surface pressure distribution at the contact end between the slot (rotor core 2) and the wedge 5 in the embodiment (FIG. 8). This figure shows that the concentration of surface pressure at the contact ends 8 between the wedge 5 and the rotor core 2 (both ends of the groove 13) is significant as in the conventional example; The relative slip between the wedge 5 and the rotor core 2 as shown in FIG. 12 can be followed fairly easily. Therefore, there is no longer a pawl-like function as in the prior art, and a rotor with high fatigue strength can be obtained without the risk of tensile or compressive stress being particularly concentrated.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to alleviate the concentration of surface pressure at the contact surface between the slot and the ends of adjacent wedges inserted into the slot provided in the rotor core, and to prevent fretting damage caused by bending and deflection of the rotor. This can prevent the occurrence of fatigue and improve fatigue strength.

[Brief explanation of drawings]

Fig. 1 is a partial sectional view of a conventional turbine generator rotor, Fig. 2 is a partially cutaway side view of Fig. 1, Fig. 3 is a perspective view showing the assembled state of the slot and wedge of Fig. 2, and Fig. 4 The figure is a front view of the deformation state of the rotor, and Figures 5 and 6 are diagrams showing the cross section of the contact end and its surface pressure distribution when a conventional wedge is used, and the tensile and compressive stress distribution at the contact end. 7 is a diagram showing the relationship between contact surface pressure and fretting fatigue strength in the conventional example, FIG. 8 is a perspective view of the slot portion of the embodiment according to the present invention, and FIGS. 9 and 10 are diagrams in FIG. 11 and 12 show the surface pressure distribution at the contact end of the slot and wedge of the embodiment shown in FIG. 8, and the tensile/compressive stress distribution at the contact portion, respectively. FIG. 2...Rotor core, 3...Slot, 5...Wedge, 7B...Contact surface, 9...Wedge end surface,
13...Groove.

Claims (1)

[Claims] 1. A turbine generator rotor in which a large number of slots are provided in the axial direction on the outer circumferential surface of the rotor, a coil is inserted in the lower part of these slots, and a plurality of wedges adjacent to each other in the axial direction are inserted in the upper part of the slots. Formed between the axial end faces of adjacent wedges of the contacting slot surfaces.
A groove having an opening having a width larger than at least the maximum distance between the axial end faces of the wedges, which is generated due to deflection of the rotor during operation, faces between the ends of the wedges. A gap is formed along an intersection line that intersects with the slot surface, and the position is such that the axial end surface of the wedge is formed in the slot due to the difference between the deflection of the rotor and the deflection of the wedge during operation. A turbine generator rotor characterized in that the end face remains within the opening of the groove even when moved relative to the face.