Patent ID: 6114793
Filing Date: 2000-09-05
Classification: H02K

Abstract:
An automotive alternator comprising:a shaft supported in a case so as to be able to rotate freely;a rotor disposed in said case and composed of a pair of pole cores which have a plurality of trapezoidal claw-shaped magnetic poles projecting from outer circumferential edge portions thereof, respectively, and which are secured to said shaft facing each other so that said claw-shaped magnetic poles intermesh; anda stator having a stator core and a stator coil disposed within said case so as to be positioned around the periphery of said rotor, whereineach of shoulder portions positioned on both axial ends of the diametrically outermost portions of said claw-shaped magnetic poles is formed into a beveled or curved outer circumferential surface; andeach of diametrically outermost leading-edge face portions positioned on the leading edges in the direction of rotation at both axial ends of said diametrically outermost portions of said claw-shaped magnetic poles is formed into an outer circumferential surface inclined in a circumferential direction by a surface which passes through a point A where the inner circumferential edge of a diametrically outermost leading-edge face positioned on said leading edge in the direction of rotation of said diametrically outermost portion of each of said claw-shaped magnetic poles intersects a plane which passes through an axial end of said stator core and perpendicularly intersects the axis of said shaft, and a point B located on a ridge line where said diametrically outermost leading-edge face intersects said beveled or curved outer circumferential surface formed in said shoulder portion,wherein an angle .alpha., defined by a ridge line where said beveled or curved outer circumferential surface formed on said shoulder portion intersects the outer circumferential surface of said diametrically outermost portion of said claw-shaped magnetic pole and a ridge line where said circumferentially-inclined outer circumferential surface formed in said diametrically outermost leading-edge face portion of said claw-shaped magnetic pole intersects said outer circumferential surface of said diametrically outermost portion of said claw-shaped magnetic pole, is greater than or equal to 40 degrees and less than or equal to 70 degrees.