1. Field of the Invention
The present invention relates to a core, particularly a core for a motor, formed from powder which has a high degree of freedom of shape (i.e. which can be formed into a wide variety of shapes), and to a motor for a vehicle using the core. The core can beneficially be used in place of a conventional electric steel plate.
2. Description of the Related Art
Because an increasing number of vehicles are manufactured to be electrically operated and be more environmentally friendly, conventional vehicle systems that have been driven by hydraulic pressure have developed into systems that are electrically driven. This has caused an increase in the type and number of motors that are used in vehicles. For example, high-grade vehicles may have as many as 100 or more motors.
As the demand for motors has increased in this way, motors are also required to be smaller and more lightweight. For instance, the size and weight of motors have been reduced in such a manner that conventional DC motors are either structurally changed into BLDC (“brushless DC”) motors or high-performance magnets are utilized. Furthermore, high frequency and high rotation of vehicle use may contribute to a further need to increase the output of the motor and to decrease the size further.
FIG. 1 shows a conventional motor for vehicles, and FIG. 2 shows a stator core used in the motor of FIG. 1. Conventionally, a core 30 which constitutes a large volume of a motor 70 comprises a laminated electric steel plate 32. The high flux density, high permeability and high strength of this electric steel plate 32 provide advantages, and, thus, it is widely applied to a core 30 of a motor for vehicles.
However, the electric steel plate 32 is problematic because only a 2D magnetic circuit is formed and the degree of freedom of shape is low. Upon designing the motor 70, the confined structure of the electric steel plate 32 cannot be easily applied. For example, the core 30 comprising the electric steel plate is configured such that a rotor 10 is positioned in the core 30 and a wire 60 is wound on the outer surface thereof. As such, wound wire may be disposed on the outer surface of the core at a height that increases the core size, and as a result the axial length of the motor may increase.
Further, the type of wire 60 typically used is a copper (Cu) wire, which is expensive and has a high density. As a result, use of wound Cu wire can result in an increase in cost and weight.
Further, the conventional electric steel plate 32 has a low degree of freedom of shape, such that an electric steel plate 32 is generally formed with undesirably sharp corners. These sharp corners can cause the coating of the wire 60 to undesirably peel off. To prevent this peeling, an insulating part, such as an insulator 50, is additionally attached to the outer surface of the core 30 to prevent the coating of the wire from peeling off.
This related art is merely utilized to enhance understanding about the background of the present invention, and should not be regarded as conventional techniques known to those having ordinary knowledge in the art.
USPTO Backgrounds
USPTO Backgrounds