Abstract: A brushless motor including a toothed part with a tooth main body and a tip part. Protruding slant parts are formed on both sides of the tooth tip part. A tip surface is formed on the inner diameter of the tip part to face a magnet. A groove part is recessed in the center of the tip surface and extends in the axial direction. A depth d of the groove part satisfies 0<d?(Lx?Rt)/3. A width Wg of the groove part satisfies Wt>Wg?Wt/2 (Lx: distance between rotor center and a tooth/slant intersection X; X: intersection between an extension line P of a circumferential side surface of the tooth main body and an extension line Q of a slope of the slant part; Rt: radius of the inner diameter of the tooth tip surface; Wt: width of the tooth main body).

Abstract: A rack-assist type electric power steering device (10) uses a motor (1) as a drive source. The stator (11) of the motor (1) includes a stator core (13) having ring-like yoke portion (16) and teeth (17) projecting from the yoke portion (16) in the inner direction. In the stator core (13), the ratio (Wy:Wt) between the width (Wy) of the yoke portion (16) in the radial direction and the width (Wt) of the teeth (17) in the circumferential direction is 1:1.4 to 1.8.

Abstract: [Problems] To provide a motor for EPS which can exhibit a desired performance while satisfying severe limitation on physical size. [Means for Solving Problems] In a motor for a rack assist type electric power steering system arranged coaxially around a rack shaft coupled with a steering wheel and supplying a steering assist force to the rack shaft, the motor has a six-pole, nine-slot structure and the ratio between the number of turns and the wire diameter of a winding (number of turns/wire diameter of winding) is set in the range of 15-25. Consequently, a motor for EPS in which physical size, output, heat generation, steering feeling, cost, and the like, are satisfied in good balance can be obtained. Since numeric values conforming to EPS specification are set for the ratio of number of turns/wire diameter of winding, specification at each part of the motor can be determined in accordance with these values resulting in optimization of design or reduction in manhour of design.

Abstract: Brushless motor (1) which is an electric motor, is provided with a stator unit (3) inserted in and engaged with case (2). A part of the coating material (21) for coating the coil (17) of the stator unit (3) enters the receiving part (13) formed in the bottom part (2B) of the case (2); and the bottom part (2B) of the case (2) and the coil (17) are linked by this coating material (21). While coating, the coating material (21) is dripped from the opening side of the case (2) with the stator unit (3) in the inserted condition in the case (2).

Abstract: [PROBLEMS] To provide a motor for EPS which can exhibit a desired performance while satisfying severe limitation on physical size. [MEANS FOR SOLVING PROBLEMS] In a motor for a rack assist type electric power steering system arranged coaxially around a rack shaft coupled with a steering wheel and supplying a steering assist force to the rack shaft, the motor has a six-pole, nine-slot structure and the loading ratio (2P?/(ZI/a)) of its magnetic loading (2P?) to electric loading (ZI/a) is set in the range of 100-300. Consequently, a motor for EPS in which physical size, output, steering feeling, cost, and the like, are satisfied in good balance can be obtained. Since a numeric value conforming to EPS specification is set for the loading ratio, specification at each part of the motor can be determined in accordance with that value, resulting in optimization of design or reduction in manhour of design.