JPH0315239A - turbine generator rotor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

[Conventional technology]

Conventionally, this type of rotor has slots 3 in a rotor core 2 formed integrally with the shaft l, as shown in FIGS. 1 to 3.
A large number of coils 4 are provided in the axial direction, and a coil 4 is inserted into the lower part of these slots 3, and a spacer 6 is placed on this coil 4.
It has a structure in which a plurality of wedges 5A are inserted into the upper part of the slot 3 so that the wedges 5A are positioned through the slots 3.
A prevents the coil 4 from escaping from the slot 3 due to centrifugal force caused by rotation of the rotor.

[Problem to be solved by the invention]

The wedge 5A may be formed into various shapes, but is generally formed into a dovetail shape as shown in FIGS. 2 and 3, and other shapes such as a T-shape and a Christmas tree shape are also used. These wedges 5A are slot 3
Since a plurality of wedges are inserted into the slot 3, there is always a contact end 8 on the contact surface 7' between the wedge 5A and the slot 3, where the end surfaces of the adjacent wedges 5A are in contact with each other. Not only is surface pressure concentrated on this contact end 8 due to centrifugal force, but also a slot is formed when the rotor core 2 rotates with a curvature r due to its own weight or bending vibration, as shown in FIG. An opposing deviation ±δ occurs between the rotor core 2 and the wedge 5A. 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 this area.

In FIG. 4, if the radius of the rotor is r0 and the length of the wedge 5A is 0, the rotor core 2 is located at the upper point A and the lower point B.
When reaching δ (=±
-! -i-Q), but the wedge 5A does not expand or contract because it is divided in the longitudinal direction. Therefore, for each revolution of the rotor, the wedge
Relative slip 2δ (
=-12).

r As mentioned above, the contact pressure is concentrated at the contact end 8, and it is generally known that when a contact surface with high contact pressure is accompanied by relative slip, the fatigue strength will be significantly reduced due to fretting damage. This is a problem.

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 increases rapidly at the contact end 8. If the high surface pressure end undergoes relative sliding, 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. 6. Recognize. The relationship between the contact surface pressure and the fretting fatigue strength is as shown in Figure 7, and from this figure, the contact surface pressure has a great effect on the fretting fatigue strength.
It can be seen that when the contact surface pressure is reduced to a certain extent, the decrease in fatigue strength is rapidly reduced and the strength is improved.

In Utility Model No. 57-27838, slits were provided in the rotor teeth between the body grooves to separate them in the axial direction, and contact was established between the rotor teeth and the wedges due to the difference in thermal expansion. Techniques have been disclosed for alleviating the axial stress generated on the surface. However, this technique did not take into consideration the concentration of pressure on the contact surface between the rotor teeth and the wedges.

Furthermore, Japanese Patent 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. The problem was that the surface pressure actually increased. In view of the above, the present invention alleviates the concentration of surface pressure at the contact surface between the slot and the ends of adjacent wedges inserted into the slots 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 to solve the problem]

In order to achieve the above object, the present invention provides a turbine generator rotor in which a large number of slots are provided in the axial direction on the outer peripheral surface of the rotor, and a coil and a plurality of wedges are inserted into the lower and upper parts of these slots, respectively. , a portion is formed at least in part of the axial end of the wedge, where the wall thickness of the wedge in the direction perpendicular to the contact surface between the wedge and the slot is smaller than the wall thickness at the axial center portion of the wedge. It is characterized by the presence of

[Function and Examples of the Invention]

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

In FIG. 8, 5 is a wedge inserted into a slot (not shown) provided in the rotor core, and the end surface 9 of this wedge 5 has grooves 10 along the contact surface 7A in contact with the slot.
is provided. The other structures are the same as those of the conventional example shown in FIGS. 1 and 2, so drawings and explanations are omitted.

With this configuration, the wedge 5 as shown in FIG.
By reducing the rigidity in the radial direction near the contact end, that is, in the direction perpendicular to the contact surface 7A, and making the contact pressure on the contact surface 7 near the contact end almost uniform, the concentration of surface pressure on the contact surface can be alleviated. can. The surface pressure distribution can be adjusted by appropriately setting the depth Ω of illo and the distance h from the contact surface 7A.

The second embodiment shown in FIG. 10 differs from the first embodiment (FIG. 8) in that a clearance groove 11 is provided at the top of the end surface 9 of the wedge 5.
However, the other structure is the same as that of the first embodiment. With this configuration, the groove 10 can be easily processed and the strength of the end portion of the groove 10 can be prevented from decreasing.

The third embodiment shown in FIG. 11 has a groove 1 provided in the first embodiment.
0, a hollow groove 12 is provided on the end face 9 of the wedge 5. If configured in this manner, it is possible to reduce the radial rigidity of the wedge contact end and alleviate surface pressure concentration on the contact surface between the slot and the wedge, as in the previous embodiment. Therefore, since there is no longer a pawl-like function as in the prior art, 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, 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 is alleviated, and fretting damage caused by bending and deflection of the rotor is alleviated. The fatigue strength can be improved by preventing the occurrence of.

[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 using a conventional wedge, and the tensile and compressive stress distribution at the contact end. Figure, 7th
The figure is a diagram showing the relationship between contact surface pressure and fretting fatigue strength in a conventional example, and Figures 8, 10, and 1 are perspective views of the wedge end of each embodiment of the turbine generator rotor of the present invention. , FIG. 9 is a diagram showing the cross section of the contact end between the slot and the wedge end of the embodiment shown in FIG. 8, and its surface pressure distribution. 2... Rotor core, 3... Slot, 5... Wedge, 7A... Contact surface, 9... Wedge end surface, 10
...Groove, work 1...relief groove, 12...empty part. Figure 2

Claims (1)

[Claims] 1. In 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, and a coil and a plurality of wedges are inserted into the lower and upper parts of these slots, the axis of the wedge A portion is formed in at least a portion of the direction end portion, where the wall thickness of the wedge in the direction perpendicular to the contact surface between the wedge and the slot is smaller than the wall thickness at the axial center portion of the wedge. Turbine generator rotor. 2. A groove is formed in at least a portion of the axial end surface of the wedge along the contact surface between the wedge and the slot, and the groove increases the wall thickness of the wedge in the direction perpendicular to the contact surface between the wedge and the slot. 2. The turbine generator rotor according to claim 1, wherein a portion is formed that is smaller than an axially central portion of the rotor. 3. A cavity opening in the axial direction is formed in the axial end face of the wedge, and the cavity allows the wall thickness of the wedge in the direction perpendicular to the contact surface between the wedge and the slot to be greater than that at the axial center of the wedge. The turbine generator rotor according to claim 1, characterized in that a small portion is formed.