JPS62135245A - Induction machine squirrel cage rotor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a squirrel-cage rotor for an induction machine, in which a rotor conductor made of copper, brass, etc. is provided with short-circuit rings made of the same material at both ends. In this type of rotor, it is desired that the rotor conductor and the short-circuit ring be easily joined together, and that the mutual joint be strong enough to withstand thermal stress and mechanical stress. be done.

[Prior art and its problems]

In general, the squirrel cage rotor of an induction motor is widely used as a rotor of an induction motor for normal use because it has a simpler structure, is stronger, easier to handle, and is less expensive than a wound rotor. In this case, in a general induction machine as illustrated in FIG. A rotor conductor 16, which is usually made of a single piece of copper, brass, etc., is housed inside a plurality of axial through grooves formed near the outer peripheral surface of the rotor core 6 fixed to the rotor shaft 7. At the same time, shorting rings 25 made of a similar material and made of a single piece are provided at both ends thereof. As a special example, it is known that the rotor conductor 16 and the short-circuit ring 26 are integrally formed and attached to the rotor core 6, but generally the rotor conductor 16 and the short-circuit ring 26 are separately formed. As illustrated in FIGS. 9 and 10, short-circuit rings 26 are applied to both ends of the rotor conductor 16 near both end surfaces of the rotor core 6, and they are joined together using a suitable brazing material. .

However, in the squirrel-cage rotor configuration of an induction machine as illustrated in FIGS. 9 and 10, when the induction machine is overloaded, the current in the rotor conductor 16 and the short-circuit ring 26 becomes excessive. Due to the t1 heat loss, the rotor conductor 1
6 and the temperature of the short-circuited ring increases significantly, causing thermal expansion. In this case, the axial expansion of the rotor conductor 16 causes all the conductors 1
6 is not necessarily uniform, and centrifugal force accompanying rotation acts on the short circuit ring 26, which is relatively heavy and also causes thermal expansion. Fatigue occurs in the rotor conductor 16 and short-circuit ring 26 near the mutual joint due to both thermal stress and mechanical stress, and as the above phenomenon is repeated each time the induction machine is operated, finally near the joint. The disadvantage is that cuts in the rotor conductor 16 or in the shorting ring 26 are unavoidable.

[Purpose of the invention]

A conventional squirrel cage type induction machine in which both ends of a rotor conductor, which is a single piece, is housed inside a plurality of grooves in the axial direction of the rotor core, and both ends thereof are short-circuited by a short-circuiting ring, which is also made from a single piece. In view of the above-mentioned drawbacks of the rotor, the present invention provides a structure in which the short-circuit ring and the rotor conductor can be easily joined in the rotor core, the cooling efficiency is the same, and the centrifugal force acting on itself is reduced. By configuring the rotor conductor to reduce the thermal stress and mechanical stress generated near the joint between the rotor conductor and the short-circuit ring, it is possible to prevent a breakage accident of the rotor conductor or the short-circuit ring. It is an object of the present invention to provide a squirrel cage rotor for an induction machine that can prevent the above problems.

[Key points of the invention]

In order to achieve the above object, the present invention provides the squirrel cage rotor as described above, in which the short circuit ring is constituted by a plurality of annular bodies made of conductors having appropriate cross-sectional shapes, and each of the annular bodies is connected to the rotor. By axially arranging them at both ends of the conductor and fixing them by appropriate means, it is possible to reduce the centrifugal force acting on the short-circuit ring and improve its cooling efficiency.

[Embodiments of the Invention] Next, the present invention will be described in detail based on embodiments shown in the drawings.

In the induction machine according to the present invention as well, as illustrated in FIG. A rotor core 6 fixed to a rotor shaft 7
A rotor conductor usually made of a single piece of copper, brass, etc. is housed inside a plurality of axial through grooves formed near the outer circumferential surface of the rotor conductor, and the rotor conductor made of the same material and the rotor conductor made of the same material are housed at both ends of the rotor conductor. As in the case of conventional induction machines, a separately prepared shorting ring is provided.

However, in the squirrel-cage rotor of an induction machine according to the present invention, the short-circuit ring is formed by arranging a plurality of annular bodies made of conductors having appropriate cross-sectional shapes in the axial direction at both ends of the rotor conductor, and using appropriate means. The rotor conductor is fixed to the rotor conductor.

In the embodiment shown in FIGS. 1 and 2, the rotor core 6 has a deep groove-shaped slot, and a rectangular rotor conductor 1 having a long side in the radial direction of the rotor core 6 is inserted into the slot. are housed, the annular bodies 2a, 2b and 2 are inserted into the three holes arranged in the rotor conductor l in the axial direction.
A short-circuit ring 2 is formed by passing through and fixing C over the entire rotor conductor l. In this case, each of the rings 2a, 2b and 2C is initially cut at one place, and after being attached to the conductor l through each hole of the rotor conductor 1, the rings 2a, 2b and 2C are cut off at one place.
The cut portions b and 2C and the portion to be joined to the rotor conductor l are brazed and fixed to form the short-circuit ring 2.

Comparing the squirrel cage rotor according to the present invention as described above with a conventional squirrel cage rotor in which a single short-circuit ring is brazed to the rotor conductor, the annular bodies 2a, 2b, and 2C
If the mutual bonding area between the short-circuit ring and the rotor conductor l increases, and the cross-sectional area of the short-circuit ring itself is the same, the surface area and therefore the heat dissipation area will also increase, which will reduce the overload of the induction machine. At this time, the heat dissipation efficiency of the heat loss due to overcurrent of the rotor conductor l and the short-circuit ring 2 is improved, the temperature rise is reduced, and the annular bodies 2a, 2b, and 2
Since each of C is much lighter than a single short-circuit ring, the centrifugal force acting on them is reduced, which occurs near the mutual joint between the rotor conductor 1 and each of the annular bodies 2a, 2b and 2C. The annular body 2a forms a rotor conductor l or a short-circuit ring in the vicinity of the mutual joint by significantly relaxing thermal stress and mechanical stress.

It becomes possible to prevent mechanical damage such as cutting of 2b and 2c. Furthermore, since the temperature rise in the short-circuit ring 2 is reduced as described above, in some cases, the cross-sectional area of each annular body may be reduced accordingly to make the short-circuit ring even lighter. It is also possible to further alleviate the mechanical stress occurring in 2a, 2b and 2C.

As another embodiment having the same effect as the embodiment shown in FIGS. 1 and 2 for the purpose of the present invention, first, in the embodiment shown in FIGS. The annular body 21a is cut at a certain place.

21b and 21c or 22a, 22b and 22C are housed in open grooves formed at both ends of the rotor conductor 11 or 12, and the annular body itself is connected and fixed to the rotor conductor 11 or 12 by appropriate brazing. The work is easier compared to the embodiments shown in FIGS. 1 and 2. In particular, the embodiment shown in FIG.
There is an advantage that it can be easily implemented even when the cross-sectional shape of the cross-sectional shape is circular.

Furthermore, in the embodiment shown in FIG. 5, slopes are formed at both ends of the rotor conductor 13, and an annular body 23 is fixed on the slopes.
The farther a, 23b, and 23c are located from the end face of the rotor core 6, the larger the im diameter J becomes and becomes an axial quantity, so the mechanical stress generated at the end of the rotor conductor 13 due to centrifugal force. As a result, the fundamental durability of the end portion of the conductor 13 can be improved.

Furthermore, in the embodiment shown in FIG.
a, 24b and 24c are arranged inside the end of the rotor conductor 14 to reduce the ring diameter and reduce the weight, thereby reducing the mechanical stress generated in the rotor conductor 14 due to centrifugal force. Similar to the example shown in FIG. 5, there is an advantage that the mechanical durability of the shaft end of the rotor conductor 14 can be improved. In this case, as shown in FIG. 4, a downward open groove may be formed on the lower surface of the end of the rotor conductor 14, and the annular bodies 24a, 24b, and 24c may be fixed in the open groove.

Furthermore, in the embodiment shown in FIG. 7, C is an annular body 23a having a circular cross-sectional shape as in the embodiment shown in FIG.

An annular body 25 with a rectangular cross section in place of 23h and 23c
a, 25b and 25c are fixed to the stepped outer surface formed at the end of the rotor conductor 15, and has the same advantages as the embodiment shown in FIG. It goes without saying that the annular body having a rectangular cross-sectional shape can also be used as appropriate in the embodiments shown in FIGS. 1 to 6 depending on the circumstances.

In the embodiments shown in FIGS. 1 to W and 7, the case where the short-circuiting ring is composed of three annular bodies has been described above, but it is possible to construct the short-circuiting ring by using other than three annular bodies so as to be effective for the purpose of the present invention. It is even more acceptable to construct it with the number of annular bodies.

〔Effect of the invention〕

As explained above, the present invention provides a squirrel-cage rotor for an induction machine in which short-circuit rings made of the same material are provided at both ends of a rotor conductor made of copper, brass, etc., in which the short-circuit rings are connected to a plurality of The annular body is made of a conductor having an appropriate cross-sectional shape, and each of the annular bodies is arranged axially at both ends of the rotor conductor and fixed by appropriate means. In addition to being extremely easy to join with the rotor conductor, the heat dissipation area of the short-circuit ring increases and its cooling efficiency improves, reducing the temperature rise in the rotor conductor and the short-circuit ring during overload. Since the weight of the short-circuit ring is divided into multiple annular bodies, the centrifugal force acting on them is reduced, thereby reducing thermal stress and mechanical stress at the joint between the rotor conductor end and the annular body. This has the effect of reducing stress and preventing mechanical damage such as cutting between the rotor conductor and the annular body forming the short-circuit ring in the vicinity of the joint.

[Brief explanation of drawings]

1 to 7 show different embodiments of the configuration of the short-circuit ring of the squirrel-cage rotor of the induction machine and the means for joining the short-circuit ring to the rotor conductor according to the present invention, one side of the rotor conductor. FIG. 8 is a schematic longitudinal cross-sectional view of an induction machine having a squirrel cage rotor, and FIG. 9 is a schematic longitudinal cross-sectional view of an induction machine having a squirrel cage rotor. 10 is a schematic vertical cross-sectional view of the vicinity of one end of a conductor of a conventional squirrel cage rotor, and FIG. 1O is a schematic front view of the same portion as FIG. 9. 1.11, 12, 13, 14.15... rotor conductor,
2a, '2b, 2c, 21a, 21b, 21c. 22a, 22b, 22c, 23a, 23b, 23c, 2
4a, 24b, 24c, 25a, 25b. 25c...Annular body, 6...Rotor core. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 10. figure

Claims (1)

[Claims] 1) In a squirrel-cage rotor for an induction machine in which short-circuit rings made of the same material are provided at both ends of a rotor conductor made of copper, brass, etc., the short-circuit rings are formed from a plurality of conductors having appropriate cross-sectional shapes. A squirrel-cage rotor for an induction machine, characterized in that the annular bodies are arranged in the axial direction at both ends of the rotor conductor and fixed by appropriate means.