JPH06245447A - Electric motor - Google Patents

Abstract

PURPOSE:To more improve cooling by heat-dissipation fins in an electric motor equipped with a rotor having the heat-dissipation fins. CONSTITUTION:The electric motor is equipped with a rotor having a rotor core 1 having a shaft hole into which a rotating shaft is fitted, a plurality of rotor bars buried in the peripheral part of the rotor core 1 along the axial direction, end rings 3 connected with respective ends of the rotor bars and respectively arranged on both end faces of the rotor core 1 and a plurality of heat-dissipation fins 4 formed integrally with the end rings 3. When the heat-dissipation fins 4 are radially extended toward the axis from the end rings 3 and joined to the end faces of the rotor core 1, the heat of the rotor core 1 is conducted from the junction of the rotor core 1 and heat-dissipation fins 4 directly to the fins 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an electric motor provided with a rotor having cooling fins for cooling.

[0002]

2. Description of the Related Art For example, an electric vehicle such as a battery forklift is equipped with a traveling electric motor, and the electric motor is required to have excellent heat dissipation because the battery forklift travels at a low speed. Therefore, as a conventional electric motor, there is known a motor provided with a heat radiation fin as shown in FIG. This rotor includes a rotor core 11 having a shaft hole 11a into which a rotation shaft (not shown) is fitted, a plurality of rotor bars 12 embedded in the peripheral edge of the rotor core 11 along the axial direction, and each end of the rotor bar 12. End rings 13 connected to the end portions of the rotor core 11 along the peripheral edges of the rotor core 11 and a plurality of heat dissipating fins 14 integrally formed on the side end surfaces of the end ring 13. There is. In this case, the heat is dissipated from the heat dissipating fins 14 into the air as the rotor rotates, so that the heat dissipating fins 14 are cooled, and accordingly, the heat is conducted from the end ring 13 to the heat dissipating fins 14.
3 is also cooled.

[0003]

However, in the case of the above-mentioned conventional rotor, the heat dissipated from the radiation fins 14 is mainly the heat generated in the end ring 13, so that the rotor bar 12
The heat generated in the rotor core 11 is not sufficiently dissipated through the heat radiation fins 14. For this reason, the temperature of the rotor as a whole rises, leading to a decrease in the efficiency of the electric motor.

The present invention has been devised in view of the above problems, and it is an object to be solved to further improve the cooling by the radiation fins in the electric motor having the rotor having the radiation fins.

[0005]

In order to solve the above-mentioned problems, the first invention is to provide a cylindrical rotor core having a shaft hole into which a rotary shaft is fitted, and a peripheral edge portion of the rotor core along the axial direction. A plurality of embedded rotor bars, an end ring connected to each end of the rotor bar and arranged on both end faces of the rotor core along the peripheral edges thereof, respectively, and a plurality of integrally formed end rings. The heat radiating fins described above are included, and the heat radiating fins extend in the centripetal direction from the end ring and include a rotor joined to the end surface of the rotor core.

The second invention adopts a novel structure in which the electric motor of the first invention is mounted for traveling of an electric vehicle.

[0007]

In the electric motors according to the first and second aspects of the invention, the heat generated in the end ring of the rotor is conducted to the heat radiation fins to be dissipated, and the heat generated in the rotor core is mainly generated between the rotor core and the heat radiation fins. The heat is dissipated by conducting directly from the joint to the heat dissipating fins. Further, the heat generated in the rotor bar is conducted to the radiating fins through the end ring and the rotor core to be radiated. As a result, the entire rotor is efficiently cooled by the radiation fins.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view showing a main part of a rotor for an electric motor according to this embodiment, and FIG. 2 is a sectional view taken along the line AA of FIG. In the figure, reference numeral 1 denotes a rotor iron core formed by stacking a large number of thin silicon steel plates into a cylindrical shape, and a shaft hole 1a into which a rotation shaft (not shown) is fitted is formed at the center thereof. A large number of rotor bars 2 made of aluminum die casting are embedded in the peripheral edge of the rotor core 1 along the axial direction. Further, cylindrical end rings 3 formed integrally with the rotor bar 2 by aluminum die casting are provided on both end surfaces of the rotor core 1, respectively.

Then, each end ring 3 is integrally formed with the end ring 3 by aluminum die casting.
The individual radiation fins 4 are radially arranged. The radiating fins 4 project outward from the outer end face of the end ring 3, extend in the centripetal direction from the inner peripheral face, and are joined to the end face of the rotor iron core 1. Also, the end ring 3
A portion between the adjacent heat dissipating fins 4 on the inner peripheral surface is formed with an inclined surface 3a having a smaller diameter as it approaches the end surface of the rotor core 1.

The rotor bar 2, the end ring 3 and the radiating fins 4 in this embodiment are formed by casting the rotor core 1 by aluminum die casting at the same time. The rotor of the present embodiment configured as described above has a rotary shaft fitted in the shaft hole 1a of the rotor core 1 and is incorporated in a housing having a stator or the like to be used as an electric motor for a battery forklift or the like. It When the rotor iron core 1, the rotor bar 2 and the end ring 3 generate heat due to the operation of this electric motor, the heat generated in the end ring 3 is released by the heat radiation fins 4.
The heat generated in the rotor iron core 1 is mainly conducted to the heat radiation fins 4 directly from the joint portion between the rotor iron core 1 and the heat radiation fins 4. Further, the heat generated in the rotor bar 2 is conducted to the heat radiation fin 4 via the end ring 3 and the rotor core 1. The radiating fins 4 thus conducting the heat are cooled by radiating the heat from the radiating fins 4 into the air as the rotor rotates, and the rotor core 1, the rotor bar 2 and the end ring 3 are also cooled accordingly. To be done.
As a result, the entire rotor is efficiently cooled by the radiation fins 4.

When the rotor rotates, an air flow is generated which flows in the centrifugal direction between the radiation fins 4 arranged in a radial pattern. This air flow smoothly flows from the inner peripheral surface 3a formed by the tapered surface of the end ring 3 to the outer end surface without turbulence. Thereby, the radiation fin 4 is efficiently cooled. As described above, according to the rotor of the present embodiment, since the heat radiation fins 4 extend in the centripetal direction from the inner peripheral surface of the end ring 3 and are joined to the end surfaces of the rotor core 1, the heat radiation fins 4 allow the rotor core to move. Since 1 is also directly cooled, the entire rotor can be efficiently cooled, and the cooling by the radiation fins 4 can be further improved. Therefore, when the electric motor of the present embodiment is used as a traveling electric motor of an electric vehicle that travels at a low speed such as a battery forklift, it is possible to effectively prevent the efficiency of the electric motor from being lowered.

Further, in the present embodiment, the portion between the adjacent heat dissipating fins 4 on the inner peripheral surface of the end ring 3 is formed by the inclined surface 3a having a smaller diameter as it approaches the end surface of the rotor core 1. As a result, the airflow smoothly flows to efficiently cool the heat radiation fins 4, and the cooling by the heat radiation fins 4 can be improved. Although the radiating fins 4 in the above embodiment are formed so as to project outward from the outer end surface of the end ring 3, as shown in FIG. It is possible to omit the heat dissipation fins 5 so as to extend in the centripetal direction only from the inner peripheral surface of the end ring 3 and to be joined to the end surface of the rotor core 1. As a result, the size in the axial direction can be reduced, so that the rotor can be downsized.

[0013]

According to the first aspect of the present invention, since the heat radiation fins of the rotor extend in the centripetal direction from the end rings and are joined to the end faces of the rotor core, the heat of the rotor iron core is directly applied to the heat radiation fins from the joints. By conducting the heat, the entire rotor can be efficiently cooled, and the cooling by the radiation fins can be further improved.

Further, according to the second invention, since the electric motor of the first invention is mounted as a traveling electric motor of an electric vehicle, the effect of improving the cooling performance of the heat radiation fins is properly exerted, and the efficiency of the electric motor is reduced. It can be effectively prevented.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of an electric motor rotor according to an embodiment.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a perspective view showing a main part of a rotor for an electric motor according to another embodiment.

FIG. 4 is a partial perspective view of a conventional rotor for an electric motor.

[Explanation of symbols]

1 ... Rotor iron core 1a ... Shaft hole 2 ... Rotor bar
3 ... End ring 3a ... Inclined surface 4 ... Radiating fin

Claims (2)

[Claims] 1. A cylindrical rotor core having a shaft hole into which a rotary shaft is fitted, a plurality of rotor bars embedded along the peripheral direction of the rotor core along the axial direction, and each end of the rotor bar. The rotor core has end rings arranged on both end faces of the rotor core along respective peripheral edges thereof, and a plurality of heat dissipating fins formed integrally with the end ring, wherein the heat dissipating fins are the end rings. An electric motor including a rotor extending in a centripetal direction from the end and joined to an end surface of the rotor core. 2. A vehicle mounted on an electric vehicle for traveling.
The electric motor described.