JPH0740774B2 - Turbine generator rotor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a large number of slots on the outer peripheral surface of a rotor in the axial direction. The present invention relates to a turbine generator rotor fixed to.

[0002]

2. Description of the Related Art Conventional rotors of this type are shown in FIGS.
As shown in the figure, a large number of slots 3 are provided in the axial direction in a rotor core portion 2 formed integrally with a shaft 1, and a coil 4 is inserted into the lower part of these slots 3 and the coil 4
It has a structure in which a plurality of wedges 5A are positioned on the upper side of the slot 3 with a spacer 6 therebetween,
The wedge 5A prevents the coil 4 from escaping from the inside of the slot 3 due to the centrifugal force generated by the rotation of the rotor.

[0003]

The wedge 5A is formed in various shapes. Generally, the wedge 5A is formed in a dovetail shape as shown in FIGS.
Shapes such as Christmas tree shapes are used. Since a plurality of these wedges 5A are inserted into the slot 3, the contact surface 7'between the wedge 5A and the slot 3 has a contact end portion 8 where the end surfaces of the adjacent wedges 5A contact each other.
Can be done Not only the surface pressure due to the centrifugal force is concentrated on the contact end portion 8, but also the slot when the rotor core portion 2 is bent and rotated by the curvature r due to its own weight or bending vibration as shown in FIG. A relative slip ± δ occurs between the (rotor core portion 2) and the wedge 5A. For this reason, since large tensile and compressive stresses concentrate in the sliding direction on the rotor core 2 side of the contact end portion 8, there is a drawback that fretting damage occurs in this portion and fatigue cracks easily occur.

In FIG. 4, assuming that the radius of the rotor is r ₀ and the length of the wedge 5A is 1, the rotor core 2 has an upper point A.
And when reaching the lower point B, the wedge 5A expands and contracts by δ shown in the following formula 1 at a position corresponding to the wedge end,
Since the wedge 5A is divided in the longitudinal direction, it does not expand or contract. Therefore, a relative slip 2δ is generated at the contact end portion 8 between the wedge 5A and the rotor core 2 every rotation of the rotor.

[0005]

[Equation 1]

As described above, the contact pressure is concentrated at the contact end portion 8, and it is well known that the fatigue strength is greatly reduced due to fretting damage when the contact surface having a high contact pressure is accompanied by relative slip. However, this is a problem in terms of strength. The surface pressure distribution on the contact surface 7'of the rotor core 2 and the wedge 5A is the fifth
As shown in the figure, it is clear from this figure that the contact pressure at the contact end portion 8 sharply increases. If the high surface pressure end makes a relative slip, a large tensile or compressive stress may concentrate on the contact end 8 on the rotor core 2 side each time a relative slip of the wedge 5A occurs, as shown in FIG. Recognize. The relationship between the contact surface pressure and the fretting fatigue strength is as shown in FIG. 7. From this figure, the contact surface pressure has a great influence on the fretting fatigue strength. It can be seen that the decrease sharply decreases and the strength improves.

In Japanese Utility Model Laid-Open No. 57-27838, a slit is formed in the rotor tooth portion between the body grooves so as to partition the rotor tooth portion in the axial direction. A technique for relieving the axial stress generated in the above is disclosed.
However, in this technique, no consideration was given to the concentration of contact surface pressure between the rotor tooth portion and the wedge.

Further, 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 relative slip amount. In this case, the contact area is reduced. As a result, the contact surface pressure is rather high.

In Japanese Utility Model Publication No. 51-28593, there is a wedge for a rotor in which a hollow groove is provided at both ends of an elliptic or nearly flat bar and diametrical ridges are provided at both ends of the rod to prevent the rotor from falling off. It is disclosed. However, this wedge has a cylindrical shape with hollow portions provided at both axial ends of the rod-shaped body, and the surface pressure exerted by the wedge on the rotor due to bending bending and centrifugal force of the rotor is the side portion of the wedge (see FIG. 2). It is not relaxed on the upper side of the portion where the ridge is formed).

In Japanese Utility Model Publication No. 52-5209, wedge 1
There is disclosed a wedge for a rotor of a rotary electric machine in which a fixing groove 7 is formed on the end surface of the wedge to insert a fixing pin 6 to prevent the wedge 1 from moving in the axial direction. In this wedge,
The groove is formed on the outer peripheral side of the surface that receives the surface pressure due to the bending bending and centrifugal force of the rotor, and the effect of reducing the surface pressure cannot be obtained.

In view of the above, the present invention alleviates the surface pressure concentration on the contact surface between the adjacent wedge end portions inserted into the slots of the rotor core and the slots, and prevents the occurrence of fretting damage due to bending bending of the rotor. It is an object of the present invention to provide a turbine generator rotor having high fatigue strength by preventing it.

[0012]

In order to achieve the above object, the present invention provides a large number of slots on the outer peripheral surface of a rotor in the axial direction, and a coil and a plurality of wedges are provided in the lower and upper parts of these slots, respectively. In the inserted turbine generator rotor, a portion of the wedge axial end surface along the wedge surface that receives radial surface pressure due to centrifugal force projects in the axial direction, and the projecting portion is perpendicular to the wedge surface and parallel to the axial direction. It is characterized in that the cross section cut by a flat plane has a substantially triangular shape that becomes thinner toward the tip.

[0013]

The operation will be described in the section of the next embodiment.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The operation and embodiments of the present invention will be described below with reference to the drawings.

In FIG. 8, reference numeral 5 denotes a wedge inserted in a slot (not shown) provided in the rotor core, and an axial end surface 9 of the wedge 5 is vacant along a contact surface 7A in contact with the slot. How section 12 is provided. The surface of the eave-shaped protruding portion forming the hollow portion 12 that faces the slot surface forms a wedge surface 7A, and this protruding portion is perpendicular to the wedge surface 7A and parallel to the axial direction. The cross section cut by a plane is formed in a shape that is substantially triangular, with the tip becoming thinner. Other structures are the same as those of the conventional example shown in FIGS. 1 and 2, and therefore the drawings and description thereof are omitted.

According to this structure, the rigidity in the radial direction near the contact end (axial end) of the wedge 5, that is, in the direction perpendicular to the contact surface 7A, is reduced, and the surface pressure of the contact surface 7 near the contact end is reduced. By making them substantially uniform, the surface pressure concentration on the contact surface between the slot and the wedge surface 7A can be relieved. The surface pressure distribution can be adjusted by appropriately setting the depth of the hollow portion 12 and the distance from the contact surface 7A. Therefore, since the function of raising the claw as in the conventional case is eliminated, it is possible to obtain a rotor having high fatigue strength without fear that tensile or compressive stress is particularly concentrated.

[0017]

As described above, according to the present invention, the surface pressure concentration at the contact surface between the adjacent wedge end portions inserted into the slots provided in the rotor core and the slots is alleviated, and the rotor is bent. It is possible to prevent the occurrence of fretting damage due to bending and improve the fatigue strength.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a conventional turbine generator rotor.

2 is a partially cutaway side view of FIG. 1. FIG.

FIG. 3 is a perspective view showing an assembled state of the slot and wedge of FIG.

FIG. 4 is a front view of a deformed state of a rotor.

FIG. 5 is a diagram showing a cross section of a contact end portion and a surface pressure distribution thereof when a conventional wedge is used, and a tensile / compressive stress distribution chart of the contact end portion.

FIG. 6 is a diagram showing a cross-section of a contact end and a surface pressure distribution thereof when a conventional wedge is used, and a tensile / compressive stress distribution diagram of the contact end.

FIG. 7 is a diagram showing a relationship between contact surface pressure and fretting fatigue strength in a conventional example.

FIG. 8 is a perspective view of a wedge end portion of the embodiment of the turbine generator rotor of the present invention.

[Explanation of symbols]

 2 Rotor core 3 Slot 5 Wedge 7A Contact surface 9 Wedge end surface 12 Cavity part

Claims (1)

[Claims] 1. A turbine generator rotor comprising a rotor outer peripheral surface provided with a number of slots in the axial direction, and a coil and a plurality of wedges respectively inserted in the lower and upper parts of these slots. A portion along the wedge surface that receives radial surface pressure due to centrifugal force projects in the axial direction, and a cross section obtained by cutting the projecting portion with a plane perpendicular to the wedge surface and parallel to the axial direction has a substantially triangular shape in which the tip portion becomes thinner. A turbine-generator rotor characterized in that it does not.