JPH04121045A - Squirrel-cage rotor - Google Patents

Abstract

PURPOSE:To prevent separation of a conductor due to a centrifugal force and to improve an exciting current, a power factor, an efficiency by providing a groove on the outer periphery of a core, burying the conductor in the groove, and engaging a thin-wall pipe of a magnetic element with the outer periphery of the core. CONSTITUTION:A rectangular groove 32 is provided on the outer periphery of a columnar core 31 integral with the shaft 31a of a magnetic element supported by bearings 39a, 39b, and a soft copper conductor 33 is buried from its radial outside. A thin-wall pipe 35 of a magnetic element is engaged with the outer periphery of the core 31 in which the conductor 33 is buried in the groove 32. According to this structure, the conductor 33 is burdened with centrifugal force generated by a high speed rotation on the thin-wall pipe 35 to eliminate a fear of separation of the conductor 33, and the bending rigidity of a squirrel-cage rotor 30 is increased by the pipe 35. The groove 32 is closed by the pipe of the magnetic element to reduce a magnetic resistance of an air gap between stators, to improve an exciting current, a power factor, an efficiency, and to particularly suppress temperature rise of a light load. Thus, even if it is left to stand in a working field as a concrete vibrator with the switch remaining closed, fear of burning can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a squirrel cage rotor of a small diameter and axially long electric motor used in concrete vibrators and the like.

[Conventional technology]

Fig. 2 is a perspective view of a general concrete pie break common to the conventional example and the embodiment, Fig. 3 is a joint cross-sectional view of the conventional example 1 with a rotated cross-section added, and Fig. 4 is a sectional view of a main part of Conventional Example 2. In addition, Figure 4 is a patent application flat>
No. 114802.

In FIG. 2, the high break consists of an electric motor 1 and a vibrating part 2 having an eccentric vibrator with an eccentric center of gravity. For example 200
Connected to a high frequency power source of ~250 Hz. The electric motor 1 and the vibrating part 2 are combined and made quite elongated as a whole, which is convenient for pushing into fresh concrete and removing air bubbles by vibration.

In the conventional example 1 shown in Part 3, the squirrel cage rotor 10 is extremely long and slender, and the total length is 5 to 10 times the diameter. cannot be formed. Therefore, a rectangular groove 12 is cut in the outer periphery of the cylindrical core 11 that is integral with the magnetic shaft 11a, and a conductor 13 made of mild steel or the like is buried from the outside in the radial direction and is pressed against the wall of the groove 12 by hitting with a hammer. Fix it. The short-circuiting ring 14 is rounded by applying a U-shaped conductor, and is soldered to the conductor 13 in a ring shape at the same time as the part a is soldered to the conductor 13.

In conventional example 2 shown in FIG. 4, in order to prevent the conductor from coming off the groove due to centrifugal force, a concave I425 is formed in the groove 22 of the iron core 21, which is integrated with the axis of the squirrel-cage type mass rotor 20, and the conductor 23 is The conductor 23 is inserted into the concave groove 25 in the radial direction by pressing it from the outside with a roller or the like to plastically deform the conductor 23 and push it into the concave groove 25.

In both Conventional Examples 1 and 2, the reason why the conductor 13 or 23 is buried from the outside in the radial direction instead of being inserted in the axial direction as usual is because the cage-shaped quantity trochanter 10.20 is long and narrow, and the groove IL21 is even longer and narrower. This is because unless a gap is provided, the conductor cannot be inserted in the axial direction. If a gap is provided, the conductor may be destroyed during use as a vibrator. Because the conductor is embedded from the radial direction, the groove becomes a so-called open slot, which increases the magnetic resistance of the air gap, which mainly causes an increase in excitation current and a decrease in power factor and efficiency.Mechanically, it separates due to centrifugal force at high speed rotation. There is a risk that

[Problem to be solved by the invention]

In the prior art described above, since the electric motor has a small diameter and is long in the axial direction, the grooves in the rotor core are naturally elongated in the axial direction G. Therefore, it is not possible to insert a rod-shaped conductor through the iron core twice in the axial direction.
It will be buried from the outside in the radial direction, and the groove will be a so-called open slot. Therefore, mechanically, the conductor easily separates from the groove due to the centrifugal force of high-speed rotation, and it is necessary to strike it from the outer periphery to cause it to plastically deform. Electrically, when the effective gap length is 71, an increase in excitation current and a decrease in power factor and efficiency are unavoidable, and this tendency is particularly strong when there is no load or a light load close to no load. When used as a concrete vibrator in areas with large rises, cooling is good because there is an electric motor inside the ready-mixed concrete. The load is almost light, there is no cooling by fresh concrete, and the temperature rise is large enough to cause burnout.

The purpose of this invention is to reliably prevent separation of the conductor due to centrifugal force Q in squirrel-cage type mass trochanters that are long and slender and operate at high rotational speeds where neither a laminated iron core nor an aluminum die-cast conductor can be used. The object of the present invention is to provide a squirrel-cage type quantum trochanter with increased power factor and efficiency.

[Means for Solving Two Problems] The squirrel cage type quantum trochanter of the present invention includes a cylindrical iron core that is integral with the shaft, and a rod-shaped conductor that extends in the axial direction on the outer circumference of the iron core and is embedded from the radially outer side. a plurality of grooves that are open to the outer periphery, a conductor buried in the grooves, an annular shorting ring fixed to both ends of the conductor, and a magnetic material fitted to the outer diameter of the iron core. It consists of a thin-walled pipe.

[Effect]

Since the groove is open on the outer periphery in the radial direction, the conductor can be buried in the groove from the outside in the radial direction without a thin-walled vibrator. If a thin-walled pipe made of magnetic material is fitted after burying, the thin-walled vibrator will withstand the centrifugal force applied to the conductor, and at the same time, the groove will be closed with the magnetic material, increasing the effective gap length of the air gap with respect to the stator, and increasing the excitation current. Improvements in power factor and efficiency are particularly noticeable during no-load or light loads close to no-load. Therefore, it is possible to provide an electric motor that is sturdy and has no risk of burning when used in concrete hybridizers and the like.

3 Embodiment] FIG. 1 shows an embodiment, and is a joint sectional view with a rotating cross section added, and is used in the state shown in FIG. 2. Items with the same reference numerals as those in the conventional example and each figure have approximately the same functions,
Explanations may be omitted below.

In FIG. 1, in the electric motor 1 to which the vibrating part 2, only a part of which is shown, is fixed, a stator core 36 around which a stator coil 36a is wound is press-fitted into the inner diameter of a stator frame 37 on the stator side, and Bearings 39a are attached to the brackets 38a and 38b,
39b.

A magnetic shaft 31a supported by the bearings 39a and 39b.
A rectangular or U-shaped groove 32 is cut in the outer periphery of a cylindrical iron core 31 that is integral with the cylindrical core 31, and a conductor 33 made of soft copper or the like is buried from the outside in the radial direction. The short-circuiting ring 34 is rounded by applying a U-shaped conductor, and at the same time as the conductor 33 is soldered or welded to the conductor 33 at part a, it is welded to the conductor 33 in a two-ring shape.

As a characteristic structure of the squirrel cage rotor 30 of the embodiment, the conductor 33 is buried in the groove 324, and a thin magnetic pipe 35 is fitted onto the outer diameter of the iron core 31. Shrink fit, press fit, adhesive, etc. can be used for fitting. Thin wall pipe 35) and short circuit ring 34
The short-circuit ring may have a length that spans , or may be made a little shorter than the conductor 33, and the conductor and the short-circuit ring may be brazed together after fitting. The thin-walled pipe 35 is not limited to one long pipe, and may be divided into a plurality of short pipes.

According to the structure of this embodiment, the thin-walled pipe 35 bears the centrifugal force due to high-speed rotation of the conductor 33, so there is no fear of the conductor 33 coming off, and the bending rigidity of the squirrel-cage-shaped mass trochanter 30 is also increased by the thin-walled pipe 35. do. The groove 32 is closed with a thin magnetic pipe, which reduces the magnetic resistance of the air gap between the stators, improves the excitation current, power factor, and efficiency, and suppresses temperature rise, especially under light loads, making it suitable for use as a concrete vibrator in the workplace. There is no risk of burnout even if the switch is left on.

To explain a modification of the above embodiment, the diameter of the shaft 31a at both ends of the short-circuit ring 34 can be made equal to or thicker than the diameter of the short-circuit ring. Even if it is not possible to form the shape as shown in Figure 4, the centrifugal force resistance of the conductor can be ensured by using a thin-walled pipe. axis 31
If a is made thicker, the bearings 39a and 39b will also be larger, and even if the diameter of the stator frame 3τ is limited, the rigidity of the bearings, shaft, and rotor will increase, so a thinner concrete vibrator will provide durable rotation even during high-speed operation. You can have a child.

〔Effect of the invention〕

The squirrel cage rotor of the present invention includes a cylindrical iron core that is integral with the shaft, and a plurality of G holes that extend in the axial direction on the outer periphery of this iron core and that allow rod-shaped conductors to be embedded from the radially outer side. , a conductor buried in this groove, an annular short-circuit ring fixed at both ends of the conductor, and a thin-walled magnetic pipe fitted to the outer diameter of the iron core. Even in cases where the squirrel-cage rotor is extremely long and slender and the conductor must be buried in the groove from the outside in the radial direction, the mechanical seal improves the centrifugal force resistance of the conductor and the bending rigidity of the rotor. Electrically, it has the effect of improving excitation current, power factor, and efficiency, and preventing burnout accidents under light loads such as when using concrete vibrators, where switches are left open in the workplace. . Milling the grooves to increase the dimensions of the shaft and bearings; this has the effect of increasing the strength of the shaft, bearings, and rotor even in a thinner electric motor, and making it possible to rotate at higher speeds as a high break.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment, and is a vertical cross-sectional view with a rotating cross-section attached, Fig. 2 is a perspective view of a general concrete vibrator common to the conventional example and the embodiment, and Fig. 3 is a conventional concrete vibrator. FIG. 4 is a vertical cross-sectional view showing Example 1, with a rotating cross-section added; FIG. 4 is a cross-sectional view of a main part of Conventional Example 2; ■...Electric motor, 2...Vibration part, 10.20 30.
...Squirrel cage trochanter, 11,21.31...Iron core, 11
a. 31a...shaft, 12,22.32...groove, 13.2
3□33...Conductor, 14.34...Short ring, 25.
... Concave groove, 5... Thin wall pipe. Figure Figure Figure Figure

Claims (1)

[Claims] 1) A cylindrical iron core integral with the shaft, a plurality of grooves extending in the axial direction on the outer periphery of this iron core and opening in the outer periphery so that rod-shaped conductors can be buried from the outside in the radial direction; 1. A squirrel-cage rotor comprising a conductor, an annular short-circuit ring fixed to both ends of the conductor, and a thin-walled magnetic pipe fitted to the outer diameter of the iron core.