JP2000166197A - Rotating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of the strength of welded structure between the rotor bar and short circuit ring of a rotating machine. SOLUTION: A rotating machine has a rotor core in which a plurality of radial direction slots 14 are formed concentrically with approximately the same intervals, a short-circuit ring 9 made of copper (or copper alloy) and rotor bars 12 which are inserted into the respective slots 14 of the rotor core and the short circuit ring made of copper (or copper alloy). The rotor bar 12 and the short circuit ring 9 are welded to each other through a welding opening 15 which is formed along the rotor bar 12 in the outer circumferential surface of the short circuit ring 9. With this constitution, welded structure between the rotor bar 12 and the short circuit ring 9 which has improved productivity, very few welding defects and very little deterioration of welding strength can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique used for a rotating electric machine having a cage rotor, and more particularly, to a welding structure of a short-circuit ring and a rotor bar in the cage rotor.

[0002]

2. Description of the Related Art A conventional induction motor will be described below as a conventional rotating electric machine with reference to FIGS.

FIG. 11 shows an example of an industrial large-capacity rotating electric machine. In FIG. 11, a stator core 6 for accommodating a stator winding 7 is fixed to a stator frame 4. The cooling ventilation box 5a is the stator frame 4
It is fixed to.

On the other hand, a rotor core 8 for accommodating a rotor winding is provided.
Are fitted on the rotor shaft 1, and both ends thereof are suppressed in the axial direction by the rotor clamp 11, and are supported by the stator frame 4 via the bearing 2 and the bracket 3.

A fan 10 is fitted to the rotor shaft 1 on one or both sides.

FIG. 12 shows an example of a rotating electric machine for a railway vehicle. In FIG. 12, a stator core 6 for accommodating a stator winding 7 is fixed to a stator frame 4.

On the other hand, a rotor core 8 for accommodating the rotor windings
Are fitted on the rotor shaft 1, and both ends thereof are suppressed in the axial direction by the rotor clamp 11, and are supported by the stator frame 4 via the bearing 2 and the bracket 3.

FIG. 13 shows an end structure of a rotor of a conventional rotary electric machine. A rotor bar 12 made of copper (or copper alloy) is inserted into each radial slot of a rotor core 8 and The ends are fitted in the respective radial slots 14 of the copper (or copper alloy) short-circuit ring 9 as shown in FIG. 14 and joined by silver brazing.

However, there is a problem in that the strength of the rotor bar 12 is greatly reduced due to annealing of the rotor bar 12 due to heat input at the time of brazing, and there is a large variation in adhesion.

JP-A-56-35661, JP-A-56-41761
JP-A-56-56149, each rotor bar 12
A method suitable for automation by rotating a rotor whose ends are fitted in the respective radial slots 14 of the short-circuit ring 9 and welding in a circumferential direction while fixing a welding torch is described.

[0011] Further, in Japanese Utility Model Laid-Open No. 4-35667, the rotor bar 1 is provided.
A method is described in which the end of No. 2 is inserted inside the outer surface of the short-circuit ring and the fillet welding is performed without providing a groove.

As shown in FIG. 15, a bending load acts on the rotor bar 12 due to thermal expansion due to heat generation during operation of the rotating electric machine and strain and stress due to centrifugal force, and large strain and stress are generated at the joint with the short-circuit ring 9. In addition to the problem,
The strength around the insertion end of the short-circuit ring 9 and the rotor bar 12 is reduced. In order to eliminate the possibility of excessive stress being generated at this portion and causing breakage, a retaining ring is conventionally provided on the outer peripheral side of the short-circuit ring 9. 13 are attached.

The adoption of such a retaining ring 13 is disclosed in
It can be seen in the 117468 publication.

[0014]

The silver brazing method as a joining method of the above-described copper (or copper alloy) rotor bar for a rotating electric machine (induction motor) and a copper (or copper alloy) short-circuiting ring for the rotating electric machine (induction motor) described above has an uneven bonding. And the workability is poor, and the rotor bar is exposed to a high temperature for a long time during brazing, so that the rotor bar is completely annealed, resulting in a problem that the strength is significantly reduced.

The conventional welding method is excellent in workability because welding is performed while rotating the rotor in the circumferential direction. However, due to the circumferential arc-shaped inclination and the rotation of the rotor, the molten metal loses gravity. The problem is that there is a high possibility that the welding will flow to the part that is not yet sufficiently heated due to the influence of the influence and cause welding defects due to poor fusion, the defects will develop into cracks and the like, and the strength will decrease, and the rotor bar and the welding direction (circumferential direction of the short-circuit ring) ) Are orthogonal to each other, so that welding is performed on the outer peripheral surface of the short-circuiting ring between the rotor bars, so that the welding area is enlarged, and the rotor bar receives extra welding heat and is subjected to annealing of the rotor bar. There is a problem that the strength is significantly reduced.

[0016] The conventional rotating electric machine has such a problem, so that the reliability cannot be improved more than the present condition.

An object of the present invention is to provide a rotating electric machine capable of improving reliability without reducing the strength of a welded structure of a rotor bar and a short-circuit ring.

[0018]

The basic contents of the means for achieving the object of the present invention are that a short-circuit ring and a rotor bar in a cage rotor of a rotating electric machine are connected to each other along the length of the rotor bar along the length of the rotor bar. A rotating electric machine welded by using a welding groove provided in a direction, and welding both members of a rotor bar and a short-circuit ring of the rotating electric machine using a welding groove provided in a longitudinal direction of the rotor bar along the rotor bar. In this way, welding is improved by improving the dispersion of joints that are common in brazing, and the welding area is smaller than that of welding where the rotor is rotated while welding, and does not contribute to the welding of both members. The reduction in heat input reduces the decrease in strength, and the welding groove is parallel to the longitudinal direction of the rotor bar, so that the molten metal during welding does not flow under the influence of gravity, and To prevent the occurrence of weld defects due to defective, such as causing a decrease in strength and develop into or cracking the defect, it is possible to reduce the cause of strength reduction.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an induction motor as a rotating electric machine.
1 will be described below.

FIG. 11 shows an example of a large-capacity rotating electric machine for industrial use. In FIG. 11, a stator core 6 containing a stator winding 7 is fixed to a stator frame 4. The cooling ventilation box 5a is the stator frame 4
It is fixed to.

On the other hand, the rotor core 8 for accommodating the rotor windings
Are fitted on the rotor shaft 1, and both ends thereof are suppressed in the axial direction by the rotor clamp 11, and are supported by the stator frame 4 via the bearing 2 and the bracket 3.

A fan 10 is fitted to the rotor shaft 1 on one or both sides.

In the end structure of the rotor of the rotating electric machine,
A rotor bar 12 made of copper (or copper alloy) is inserted into each radial slot of the rotor core 8, and an end of each rotor bar 12 is connected to each radius of a short-circuit ring 9 made of copper (or copper alloy) as shown in FIG. The rotor bar 12 and the short-circuit ring 9 are welded to each other after being fitted in the directional slot 14.

For the welding, a material capable of local heating such as high-pulse Tig welding is employed, and consideration is given to suppressing a decrease in strength due to heat input during welding.

A holding ring 13 is mounted on the outer peripheral surface of the short-circuit ring 9 to which the rotor bar 12 is welded.

A plurality of embodiments in which the rotor bar 12 and the short-circuit ring 9 are welded together will be described below. The first embodiment in which the rotor bar 12 and the short-circuit ring 9 are joined by welding is shown in FIG.
This is shown in FIG. That is, the groove 1 on both sides of the rotor bar 12 on the outer peripheral surface of the short-circuit ring 9 as shown in FIG.
5 is provided in parallel with the rotor bar 12 along the rotor bar 12, and the rotor bar 12 and the short-circuit ring 9 are joined by welding as shown in FIG.

According to such a welding operation, difficult work such as pouring a wax into a narrow gap between the rotor bar 12 and the short-circuit ring 9 like a brazing is not required, and the workability is good. In addition, as compared with the conventional welding structure in which a welding bead is applied around the entire outer periphery of the short-circuit ring 9 while rotating the rotor about the rotor shaft 1, the outer periphery of the short-circuit ring 9 between the rotor bars 12 is smaller. Since there is no need to continuously form a weld bead in the circumferential direction (the direction of the arrow A in the figure), the number of weld beads that do not contribute to the joining between the rotor bar 12 and the short-circuit ring 9 is small.
It is possible to provide a welded structure of the rotor bar 12 and the short-circuit ring 9 with less strength reduction and welding defects due to heat input during joining.

Further, since the groove 15 is parallel to the rotor shaft and the rotor bar 12, the annular short-circuit ring 9, the rotor bar 12 and the groove 15 are rotated about the rotor shaft as a center to turn the groove 15 upward. In such a welding, the molten metal rarely flows from the groove 15 to the outer periphery of the short-circuit ring 9 under the influence of gravity, thereby preventing the occurrence of welding defects due to poor fusion. FIG. 16 shows the conventional brazing structure and the welding structure of the present invention in FIG.
It is an outline of the result of the test which applied bending load like No.5.
The curve obtained from the test data of the welded structure is above the curve obtained from the test data of the structure by brazing, and it has been experimentally proved that the welded structure has higher fatigue strength.

A second embodiment in which the rotor bar 12 and the short-circuit ring 9 are welded together is shown in FIGS. 2 (a) and 2 (b). That is, the height of the groove bottom of the groove 15 provided on both sides of the rotor bar 12 on the outer peripheral surface of the short-circuit ring 9 and the outer peripheral end surface 12a of the rotor bar 12 fitted into the slot of the short-circuit ring 9 are made to be the same.

In order to realize this, a part of the outer circumferential side of the portion of the rotor bar 12 fitted into the slot of the short-circuit ring 9 is cut, and the rotor bar 12 and the short-circuit ring 9 as shown in FIG. Combine.

The rotor bar 12 and the short-circuit ring 9 are welded along the groove 15 to cover the outer peripheral end surface 12a of the rotor bar 12 as shown in FIG.
A welding bead 18 is applied to the inside 5 and joined.

As described above, the welding area is increased by welding also to the cut surface of the rotor bar 12, that is, the outer peripheral end face 12a of the rotor bar 12, so that the rotor bar 1 having high joining strength can be obtained.
2 and a short-circuit ring 9 can be provided.

A third embodiment in which the rotor bar 12 and the short-circuit ring 9 are welded together is shown in FIGS. 3 (a), 3 (b) and 3 (c).

That is, as shown in FIG. 3A, the height of the slot 14 is reduced so that the outer peripheral surface of the short-circuit ring 9 becomes the same as the plane (neutral surface) 5 including the neutral axis of the cross section of the rotor bar 12. So that the rotor bar 12 and the short-circuit ring 9 are welded together.
As shown in FIG. 3B, fillet welding is performed to form a weld bead 18.

For more reliable welding than fillet welding,
As shown in FIG. 3C, the rotor bar 12 on the outer peripheral surface of the short-circuit ring 9 is formed.
Grooves 15 are provided on both sides, and the short-circuit ring 9 and the rotor bar 12 are welded and joined, and a weld bead 18 is installed in the groove 15.

FIG. 1 shows a case where welding is performed on a plane (neutral plane) 5 including a neutral axis of the cross section of the rotor bar 12 and a case where it is not welded.
7 and FIG. 18, an outline of the bending stress distribution generated in the rotor bar 12 in each case will be described.

FIG. 17 shows a bending stress distribution when welding is performed on the outer peripheral surface of the short-circuit ring 9, and the magnitude of the stress generated by the bending load is represented by the length of an arrow. It can be seen that the bending stress is maximum on the outer peripheral surface.

FIG. 18 shows the short-circuit ring 9 and the rotor bar 1 near the plane (neutral plane) 5 including the neutral axis of the rotor bar 12.
2 shows a stress distribution when welding is performed, and a portion on the outer peripheral side from the welding portion is a case where no welding is performed. In that case, the bending stress of the plane (neutral plane) 5 including the neutral axis of the rotor bar 12 becomes zero theoretically, and the strength can be increased.

A fourth embodiment in which the rotor bar 12 and the short-circuit ring 9 are welded to each other is shown in FIGS. 4A and 4B.

That is, as shown in FIG. 4A, the depth of the groove 15 provided on both sides of the rotor bar 12 on the outer peripheral surface of the short-circuit ring 9 is made deeper than the plane 5 including the neutral axis of the rotor bar 12,
The rotor bar 12 and the short-circuit ring 9 are welded by welding so that the surface of the welding bead 18 is the same as the plane 5 including the neutral axis as shown in FIG.

By welding in this manner, it is possible to provide a welding structure of the rotor bar 12 and the short-circuit ring 9 which is advantageous in strength as shown in FIG.

A fifth embodiment in which the rotor bar 12 and the short-circuit ring 9 are welded to each other is shown in FIGS.

That is, FIG. 5 shows that a groove 16 for welding is also provided around the rotor bar 12 on the side surface of the short-circuit ring 9 of the first embodiment. 12 were welded.

FIG. 6 shows a groove 16 for welding provided around the rotor bar 12 on the side surface of the short-circuit ring 9 of the second embodiment.
Was welded.

FIG. 7A shows fillet welding around the rotor bar 12 on the side of the short-circuit ring 9 of the third embodiment, and FIG. 7B shows the vicinity of the rotor bar 12 on the side of the short-circuit ring 9 of the third embodiment. Also, a groove 16 for welding is provided, and the rotor bar 12 is welded to the side surface of the short-circuit ring 9 using the groove 16.

FIG. 8 shows a groove 16 for welding provided around the rotor bar 12 on the outer circumferential surface of the short-circuit ring 9 of the fourth embodiment, and the rotor bar 12 is also welded to the side surface of the short-circuit ring 9 using the groove 16. It is intended to improve the reliability of the joining strength by joining and increasing the joining area.

A sixth embodiment in which the rotor bar 12 and the short-circuit ring 9 are joined by welding is shown in FIGS. 9A and 9B.

FIG. 9A shows the shape of the groove at the welding start point in welding using the grooves 15, 16 between the short-circuit ring 9 and the rotor bar 12 of the rotating electric machine.

As can be seen from FIG. 9A, the groove longitudinal direction of the welding start point, that is, the groove shape 17a of the section in the welding direction is an arc shape.

The welding is started from the welding start point by using such grooves 15 and 16, and the short-circuit ring 9 and the rotor bar 1 are welded.
2 is welded.

According to such a groove shape 17a, stress concentration at the welding start point can be reduced.

FIG. 9B shows the groove shape of the groove 15 before welding when the cross section is taken along a plane perpendicular to the rotor bar.

FIG. 10 shows a seventh embodiment in which the rotor bar 12 and the short-circuit ring 9 are welded to each other.

That is, the welding is started from the welding start point using the grooves 15 and 16 in FIG. 10 and the short-circuit ring 9 and the rotor bar 12 are welded as in the sixth embodiment. The groove shape at the end of the groove 15 on the welding start point side is different from that of the sixth embodiment as follows. As shown in FIG. 10, the groove shape 17b at the end of the groove 15 on the welding start point side is an inclined shape.

By reducing the angle of inclination of the inclined shape of the groove 17b, the molten metal at the time of welding is made to flow slowly, so that the member to be welded at the time of welding is surely heated, and fusion which is likely to occur at the inclined portion. Welding defects due to defects can be reduced.

[0056]

According to the first aspect of the present invention, since the strength reliability of the welded joint structure between the short-circuit ring of the rotating electric machine and the rotor bar can be improved, the effect of improving the product reliability of the rotating electric machine can be obtained.

According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, the joining area between the short-circuit ring and the rotor bar is increased, so that the welding structure of the rotor bar and the short-circuit ring having high joining strength can be rotated. The effect of further improving the product reliability of the electric machine is obtained.

According to the third aspect of the invention, in addition to the effect of the first aspect of the present invention, the bending stress applied to the welded portion between the rotor bar and the short-circuit ring is reduced, and the welding between the rotor bar and the short-circuit ring having high joining strength is performed. By providing the structure, the effect of further improving the product reliability of the rotating electric machine can be obtained. According to the invention of claim 4,
In addition to the effect of the first aspect of the present invention, the rotor bar and the short-circuit ring are welded and joined also on the side surface of the short-circuit ring to increase the joint area, and a welding structure of the rotor bar and the short-circuit ring with high reliability in joining strength is provided. The effect of further improving the product reliability of the electric machine is obtained.

According to the fifth aspect of the present invention, in addition to the effect of the first aspect of the present invention, the stress concentration at the welding start point of the rotor bar and the short-circuit ring is reduced to provide a welded structure between the rotor bar and the short-circuit ring having high joining strength. And further improve the reliability of the rotating electric machine.

According to the invention of claim 6, in addition to the effect of the invention of claim 1, by making the groove shape of the cross section in the welding direction at the welding start point inclined, it is possible to suppress the molten metal from flowing down. It is possible to ensure the heating of the member to be welded, provide a welded structure of the rotor bar and the short-circuit ring with less welding defects due to non-welding, and further improve the reliability of the rotating electric machine.

[Brief description of the drawings]

1A and 1B show a rotor welding structure of a rotating electric machine according to a first embodiment of the present invention, and FIG. 1A shows a state before welding;
(B) is a perspective view showing a state after welding.

FIGS. 2A and 2B show a rotor welding structure of a rotating electric machine according to a second embodiment of the present invention, and FIG.
(B) is a perspective view showing a state after welding.

3A and 3B show a rotor welding structure of a rotating electric machine according to a third embodiment of the present invention, and FIG. 3A shows a state before welding;
(B) is a perspective view showing a state after fillet welding, and (c) is a perspective view showing a state after welding using a groove.

4A and 4B show a rotor welding structure of a rotating electric machine according to a fourth embodiment of the present invention, and FIG. 4A shows a state before welding;
(B) is a perspective view showing a state after welding.

FIG. 5 is a perspective view showing a rotor welding structure of a rotary electric machine according to a fifth embodiment of the present invention, showing a case where the present invention is applied to the first embodiment;

FIG. 6 is a perspective view showing a rotor welding structure of a rotary electric machine according to a fifth embodiment of the present invention, which is applied to the second embodiment.

FIGS. 7A and 7B show a rotor welding structure of a rotary electric machine according to a fifth embodiment of the present invention. FIG. 7A shows a case where the present invention is applied to the third embodiment, and FIG. It is the perspective view showing the case where it deform | transformed and applied.

FIG. 8 is a perspective view showing a rotor welding structure of a rotary electric machine according to a fifth embodiment of the present invention, which is applied to the fourth embodiment.

FIG. 9 shows a rotor welding structure of a rotary electric machine according to a sixth embodiment of the present invention, and FIG. 9 (a) is a cross-sectional view of a welding groove used in manufacturing the welding structure in a longitudinal direction of the welding groove. FIG. 4B is a cross-sectional view showing a state in which a rotor bar is incorporated in the welding groove, in a cross section in a groove width direction of the welding groove.

FIG. 10 is a longitudinal sectional view of a welding groove used for manufacturing a rotor welding structure of a rotary electric machine according to a seventh embodiment of the present invention.

FIG. 11 is a sectional view of an industrial large-capacity rotary electric machine.

FIG. 12 is a sectional view of a rotating electric machine for a railway vehicle.

FIG. 13 is a cross-sectional perspective view illustrating a relationship between a rotor bar, a short-circuit ring, and a holding ring of a conventional rotating electric machine.

FIG. 14 is a partial perspective view illustrating the shape of a slot provided in a short-circuit ring of the rotating electric machine.

FIG. 15 is a perspective view for explaining a coupled state of a rotor bar and a short-circuit ring of the rotating electric machine and a load applied thereto.

FIG. 16 is a graph comparing the fatigue strength of the welded structure and the brazed structure.

17A and 17B are diagrams showing stress distributions of respective parts when a bending stress is applied to the welded structure of the rotor bar and the short-circuit ring of the rotary electric machine similar to the embodiment of the present invention shown in FIG. 5, and FIG. The figure is a front sectional view showing the joint structure and the stress distribution together.
(B) is a right side view of the structure of (a), and (c) is a top view of the structure of (a).

FIG. 18 is a diagram showing a stress distribution of each part when a bending stress is applied to the welded structure of the rotor bar and the short-circuit ring of the rotating electric machine similar to the third and fourth embodiments of the present invention, and FIG. It is the front sectional view which combined the joint structure and the stress distribution, and (b) is a right side view of the structure of (a).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotor shaft, 2 ... Bearing, 3 ... Bracket, 4 ...
Stator frame, 5: plane including the neutral axis of the rotor bar cross section (neutral plane), 5a: cooling ventilation box, 6: stator core, 7: stator winding, 8: rotor core, 9: short-circuit ring, 10 ... Fan,
11: rotor clamp, 12: rotor bar, 13: retaining ring, 14: radial slot of the shorting ring, 15: groove on both sides of the rotor bar on the outer peripheral surface of the shorting ring, 16: groove and welding around the rotor bar on the side of the shorting ring, 17a, 17b ... groove shape,
18 ... Weld beads.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Saburo Usami 502, Kandachicho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratory, Hitachi, Ltd. (72) Inventor Masataka Tanaka 3-1-1 Kochicho, Hitachi-shi, Hitachi F-term in the Hitachi Plant of Hitachi, Ltd. (reference) 5H013 LL03 MM07 PP03

Claims (6)

[Claims] 1. A rotating electric machine in which a short-circuiting ring and a rotor bar of a cage rotor of a rotating electric machine are welded using welding grooves provided along the rotor bar in a longitudinal direction of the rotor bar. 2. A rotating electric machine according to claim 1, wherein the portion of the rotor bar welded to the short-circuit ring is disposed inside the outer peripheral surface of the short-circuit ring, and the upper surface of the inner rotor bar portion is welded to the short-circuit ring. . 3. The rotor bar according to claim 1, wherein the welding portion between the short-circuit ring and the rotor bar is at least in a neutral plane including a neutral axis of a cross section of the rotor bar, and the rotor bar portion on the outer peripheral side of the welding portion is a non-welding portion. The remaining rotor welding structure of the rotating electric machine. 4. The rotating electric machine according to claim 1, wherein an end of the rotor bar is welded to the short-circuit ring by using a welding groove provided along a rotor bar on a side surface of the short-circuit ring. 5. The rotating electric machine according to claim 1, wherein the longitudinal section of the welding groove at the welding start point is arc-shaped. 6. The rotating electric machine according to claim 1, wherein the longitudinal section of the welding groove at the welding start point is inclined.