Patent ID: 6025664
Filing Date: 2000-02-15
Classification: H02K,Y10T

Abstract:
Vehicle braking apparatus comprising:a brake drum connected to a rotational shaft;an annular member formed of a ferromagnetic material;a guide frame for supporting said annular member in a position within and spaced from an inner surface of said brake drum;a plurality of annularly arranged permanent magnets circumferentially spaced apart within said brake drum in positions of uniform pitch, the polarities of said permanent magnets facing said inner surface of said brake drum alternating circumferentially;a cylindrical body defining an uninterrupted wall between said inner surface of said brake drum and said annular member; said cylindrical body being at least partially formed from a magnetically permeable material and comprising first portions disposed directly between said inner surface of said brake drum and outer surfaces of said circumferentially spaced apart permanent magnets and second portions disposed between said inner surface of said brake drum and spaces between said circumferentially spaced apart permanent magnets; said first portions having a uniform given thickness and being formed from a first material having a given magnetic permeability and said second portions having a uniform thickness less than said given thickness and being formed from a second material having a magnetic permeability substantially less than said given magnetic permeability; andan actuator means for producing axial movement of said annularly arranged permanent magnets into active positions within said brake drum and between said inner surface of said brake drum and said annular member, and inactive positions out of said brake drum.