JPS5935554A - Squirrel-cage type induction motor - Google Patents

Abstract

PURPOSE:To prevent the deformation of an end ring which is produced by a strong centrifugal force due to high speed rotation of a rotor by providing a projection which is projected from the end ring at the inner peripheral side, and allowing the projection to press a rotor core side at the retainer for the rotor core end side. CONSTITUTION:A projection 3A like a flange which is projected integrally at the inner peripheral side is formed on the end ring 3A of a squirrel-cage type rotor. On the other hand, a projection 7a which is projected at the outer peripheral side of a retainer 7 for a rotor core end plate is integrally formed. When the rotor is rotated at a high speed, a moment external force F1 produced due to the centrifugal force is acted on the end ring 3A and a cooling fin 4, but since the end ring 3A is pressed at the inner peripheral side projection 3Aa is by the projection 7a of the retainer 7 on the rotor core 1 side, a force F1 of the direction resisting against the force F1 due to the centrifugal force is acted to prevent the end ring from being deformed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a squirrel cage induction motor used as a main motor for driving an electric railway vehicle, and particularly to a squirrel cage induction motor with an improved rotor.

[Technical background of the invention and its problems]

In general, squirrel-cage type conductive motors are used to drive general industrial machinery because they do not have commutators and brushes that pose maintenance constraints compared to DC electric motors, and have a simple and robust structure. It is widely used as a source.

In the electric railway rolling stock industry, DC motors are the mainstream main motor for driving vehicles, but with the recent development of Nokwar Electronics, AC variable speed power supplies (VVVF inverter main circuit for vehicles) that can be mounted on vehicles have been developed. With the development of power sources (power supplies), drive systems that use the squirrel-cage induction motor as the main drive motor are attracting attention because they are easy to maintain and inspect, have excellent power regeneration efficiency, and are highly energy-saving. .

However, the above-mentioned squirrel cage induction motor operates at a commercial frequency of 50 Hz or 60 Hz when driving general industrial machinery.
Since the power source is used, the speed, that is, the maximum rotational speed is 2
Even in the case of the pole machine 60H2, the speed is about 3600 rpm.

On the other hand, when used as a main electric motor for a vehicle, the maximum speed or maximum rotational speed required varies depending on the mode of operation, such as suburban, long-distance express, or subway. For example, even in the case of a drive motor for a suburban commuter train with a maximum running speed of about 120 km/h, the required maximum rotation speed is generally higher than the maximum rotation speed for general industrial use. is calculated to be approximately 500 Orpm. As a result, the rotor of a squirrel-cage induction motor is forced to rotate at a higher speed and is subjected to stronger centrifugal force when used as a traction motor for a vehicle than when used for general industrial machinery as mentioned above. become. For example, keep the rotor diameter the same and increase the rotation speed to 360.
If the rotation speed is increased from Orpm to 500Orpm, the centrifugal force will be (5000/3600)" = 1.93 times, or about twice as much.For this reason, conventional squirrel cage induction motors for driving general industrial machinery Applying the same structure to vehicles as is is problematic in terms of equipment reliability and lifespan.

Figure 1 shows the squirrel-cage rotor of a conventional squirrel-cage induction motor for general industrial use.The rotor core 1 is made of a large number of laminated silicon steel plates, and the rotor core 1 is formed by aluminum casting. The child par 2, end ring 3, and cooling fins 4 are fitted onto the shaft 5 to rotate. If the rotor is rotated at high speed (approximately 500 rpm) for a long period of time, a strong centrifugal force will cause the end ring to
The cooling fins 4 are deformed from the normal imaginary line shown in FIG. 2 to the solid line, and the deformation becomes so large that the cooling fins 4 come into contact with the stator coil end 6, causing dielectric breakdown. There is a problem with permanent damage to the electric motor.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and an object of the present invention is to provide an induction motor having a squirrel cage rotor that can sufficiently withstand the strong centrifugal force caused by high-speed rotation.

[Summary of the invention]

This invention provides an end ring of a squirrel-cage rotor with a protrusion that protrudes inward, and a rotor core end temporary retainer that protrudes toward the outer circumference so that the protrusion of the end ring is provided with a protrusion on the opposite side of the rotor core. The presser foot that connects to the surface has a protrusion that reliably prevents deformation of the end ring caused by the strong centrifugal force caused by the high-speed rotation of the squirrel cage rotor, ensuring squirrel cage rotation without mechanical damage. It is a squirrel cage induction motor with a child.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. In the figure, parts having the same configuration as those in FIG. 1 are given the same reference numerals to simplify the explanation. Here, 3A in the figure is an end ring that is integrally provided at both ends (one end side not shown) of the rotor par 2 of the squirrel cage rotor.
This end ring 13 is formed with a protrusion jAa, such as a seven-flange, that protrudes integrally from the inner circumferential side thereof. This protrusion JAa has a wall thickness approximately half that of the end ring 3A, and is biased towards the rotor core 1 side of the end ring 3A, and the surface 3 A a of the protrusion 3Aa on the opposite side to the rotor core 1 side. '
and the inner peripheral surface of the end ring 3A form an inverted hook shape. On the other hand, 7 in the figure is a 1 made of rolled steel etc. that fits into the shaft 5 and is fixed by a key 8.
A protrusion 7a protruding toward the outer circumferential side of the rotor core end temporary holder 7 is integrally formed with the rotor core end holder. This protrusion 7a is biased toward the side opposite to the rotor core side of the rotor core end temporary presser 70, and has the above-mentioned hook-shaped end ring 3.
The protrusion 3Aa of A is brought into contact with a surface 3Aa' on the side opposite to the rotor core side, and the protrusion JAa is inserted between and pressed against the end plate of the rotor core 1.

Therefore, the rotor of the squirrel cage induction motor having the above-mentioned configuration is
When rotated at high speed, a moment external force F due to strong centrifugal force is applied to the end ring 3A and the cooling fins 4! acts in the direction of the arrow.

This moment external force F1 causes the conventional end ring 3 to deform as shown in FIG. Since it is pressed against the rotor core 1 side by 7a, the force F2 acting in the direction of resisting the moment external force F1 due to the centrifugal force acts on the rotor core 1, thereby preventing deformation as in the conventional case. ◎This allows the cooling fins 4 to sufficiently withstand high-speed rotation without causing mechanical damage such as contact with the stator coil end 6 and causing dielectric breakdown, and is suitable for use in driving electric railway vehicles. It can be used as a main motor.

Note that the present invention is not limited to the above-mentioned embodiments, and may be applied to the protrusion of the end ring 3A shown in FIG. 4, 9A, etc.
b and the protrusion 7b of the rotor core end temporary retainer 7, the joint surfaces 3A b' and 7b' are made into a dovetail-shaped taper shape so as to be inclined with respect to the axis of the shaft 5, so that the joint surfaces 3A b' and 7b' are tapered in a dovetail shape to be inclined with respect to the axis of the shaft 5. A configuration may also be adopted in which a larger end ring 3A and cooling fins 4 are provided with a deformation prevention effect.

Furthermore, configurations in which the cooling fins 4 are omitted from each of the above-described embodiments are also applicable.

Furthermore, in each of the above embodiments, the case of a squirrel cage rotor made of aluminum casting was described, but as shown in FIGS. 5 and 6, copper end rings separately formed at both ends of two rotor bars using copper rods The above-described method can also be applied to a squirrel cage rotor in which the end ring 3B is fitted, and in FIG.
The mutual contact surfaces 3 B a' and 7 B a' with the protrusions 3 B a and 7 B a are perpendicular to the axis of the shaft 5, and FIG. Bb' and 7Bb' are dovetail-shaped 29-shaped so as to be inclined with respect to the axis of the shaft 5.

〔Effect of the invention〕

Since this invention has been made as described in detail above, even if a strong centrifugal force is applied by rotating the squirrel cage rotor at high speed, the end ring will not be deformed, and the structure is high enough to withstand continuous high speed rotation. This results in a squirrel cage induction motor that is reliable and has a long life, and can be used as a main motor for driving electric railway vehicles. In addition, the structure is simple, and especially when manufactured by aluminum casting, the protrusion can be cast integrally, so the manufacturing man-hour is the same as that of the conventional one, and there is no problem in mass production.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the squirrel-cage rotor of a conventional squirrel-cage induction motor for general industrial machinery, Figure 2 is a cross-sectional view showing the deformed end ring of the conventional squirrel-cage rotor, and Figure 3 is FIG. 4 is a cross-sectional view of the squirrel-cage rotor portion of a squirrel-cage induction electric machine showing one embodiment of the present invention; FIG. 4 is a cross-sectional view of the squirrel-cage rotor portion showing another embodiment of the present invention; FIGS. The figures show further different embodiments of the present invention, and are sectional views of squirrel-shaped rotor parts. 1... Rotor core, 2.2 A inner rotor par, 3.
3 A -3B-...end ring, 3Aa ・3Ab
・, 9Ba3 B b ...Protrusion, '13Aa"3
Ab'-3Ba'-3Bb' - surface opposite to the rotor core side, 4... cooling fins, 5... shaft, 6...
・Rotor coil end, 7/7B... Rotor core end temporary holding, 7a/7b/7Ba7Bb... Holding is a protrusion. Applicant's agent Patent attorney Takehiko Suzue 2i No. 41 Figure 2 Figure 3

Claims (1)

[Claims] The end rings at both ends of the rotor part of the squirrel-cage rotor are provided with protrusions that protrude inwardly, and the rotor core end plates are provided with protrusions that protrude outwardly to meet the rotor core side of the protrusions on the end rings. A squirrel-cage induction motor characterized in that a presser foot to be joined to the opposite side is configured by providing a protrusion.