JPH04138056A - brushless motor - Google Patents

Abstract

PURPOSE:To obtain an axial gap type brushless motor having excellent heat dissipating properties, a small size, a large torque, high performance, high durability and high reliability by providing an axial refrigerant passage in a hollow radial center of a rotary shaft of a rotor in the motor, and providing a cooling fan in the rotor. CONSTITUTION:Reference numerals 101 and 102 denote rotors; 103, a rotary shaft coupled to the rotor, and a yoke 111 and a coil 112 are secured to a stationary flange 113 to constitute a stator. The shaft 103 becomes hollow at the radial center, and has a structure communicating with the exterior at one side of a shaft end and an axial center. In this case, cooling of the interior of a motor is performed by any of introducing and sucking refrigerant from the shaft end side into the rotary shaft by using an external unit. A fan is provided in the rotor to cool the interior of the motor and the rotor without using the external unit, and cooling performance is also improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a brushless motor used for power in industrial, household, etc. applications.

(Prior Art) Brushless motors are roughly divided into radial gap type and axial gap type in terms of structure. In conventional general axial gap type brushless motors, when the axial thickness of the coil is increased, the air gap on the magnetic circuit becomes larger and the magnetic resistance increases. Applications are limited to those that require a particularly thin design, such as motors, and have almost never been used as power motors that require small size, high efficiency, and high torque.

As an axial gap type brushless motor for power use,
As shown in FIG. 6, there is a structure in which a stator in which a coil is wound around a columnar yoke made of a soft magnetic material is arranged between a pair of opposing rotors 301 and 302.

Due to its structure, it is possible to increase the coil diameter and reduce Joule loss, and the shape of the yoke also reduces eddy current loss, hysteresis loss, and magnetic resistance, making it possible to achieve high efficiency and high output with a small size. That's what I was trying to get.

(Problems and objects to be solved by the invention) However, in the axial gap type brushless motor having the structure shown in Fig. 6, when the stator is expanded in the radial direction to use a large diameter coil, the volume occupied by the coil becomes large. In contrast, the heat dissipation area becomes smaller and the heat dissipation performance deteriorates. Furthermore, if the stator is enlarged in the axial direction, the heat dissipation of the coil improves, but iron loss in the yoke increases and the amount of heat generated increases. Furthermore, even if a refrigerant such as air is introduced from the outside to cool the stator, it is difficult to cool the center of the stator.Therefore, it is necessary to pursue a compact and high-performance product for powering electric vehicles, etc. In some cases, such a structure has problems such as insufficient heat dissipation, limited torque due to temperature rise due to Joule heat in the coil, and further reduced durability and reliability. Ta.

The present invention is intended to solve these problems, and its purpose is to provide a brushless motor that has excellent heat dissipation, is small in size, can obtain large torque, has high performance, and is also excellent in durability and reliability.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the brushless motor of the present invention is an axial gap type brushless motor. It is characterized by having the following. Further, the brushless motor is characterized in that the rotor is provided with a cooling fan.

(Example) Embodiments of the present invention will be described below based on the drawings.

In the cross-sectional view of the brushless motor shown in FIG.
1 and 102 are rotors, 103 is a rotating shaft coupled to the rotor, 111 is a yoke made of a soft magnetic material, 11
2 is a coil wound around the yoke 111;
The yoke 111 and the coil 112 are attached to a fixing flange 113
The stator is fixed by a yoke 111, a coil 112, and a fixing flange 113. FIG. 2 is a front view of the rotating shaft 103 shown in FIG. 1. The rotating shaft 103 is hollow at its center, and has a structure that communicates with the outside at one end of the shaft and at the center of the axis. There is.

In this case, the inside of the motor can be cooled by either introducing or suctioning the refrigerant from the shaft end into the flow path within the rotating shaft using an external device.

Further, FIG. 3 shows a front view of a rotor in another embodiment of the present invention. In this embodiment, the rotor has a structure in which a fan is provided on the radial center side. In this embodiment, the fan is integrated with the rotor, but it can also be made separate.

FIGS. 4 and 5 show examples of the directions in which the refrigerant flows by combining rotor fans in different directions, but these methods allow forcible cooling of the inside of the motor without using an external device.

Further, when an external device is used, the cooling effect is improved compared to the structure of the embodiment shown in FIG. The rotor fan also serves as a cooling fin, contributing to the cooling of the rotor and eventually the permanent magnets, thereby preventing a decrease in magnetic flux density caused by the temperature characteristics of the permanent magnets.

(Effects of the Invention) As explained above, the brushless motor of the present invention has a relatively simple structure in which the rotating shaft is hollow, and can effectively cool the inside of the motor, making it compact and high performance. be able to. Further, by providing a fan in the rotor, it becomes possible to cool the inside of the motor and the rotor without using an external device, and the cooling performance is also improved.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of the brushless motor of the present invention, and FIG.
3 and 3 are front views of the components of the brushless motor according to the present invention, FIGS. 4 and 5 are refrigerant circulation path diagrams of the brushless motor of the present invention, and FIG. 6 is a vertical cross-section of a conventional brushless motor. It is a diagram. 101.102 Rotor rotating shaft Yoke coil fixing member Fan integrated rotor Figure 2 Figure 3

Claims (2)

[Claims] (1) In the axial gap type brushless motor,
A brushless motor characterized in that the radial center of the rotor rotation shaft is hollow and an axial refrigerant flow path is provided. (2) The brushless motor according to claim 1, wherein the rotor is provided with a cooling fan.