Patent ID: 6305675
Filing Date: 2001-10-23
Classification: B06B,B60K,F16F

Abstract:
An oscillating force generator for an active-type vibration damper comprising:a yoke member made of a magnetic material and having an annular groove open in one of axially opposite end faces thereof, such that said yoke member has an inner and an outer circumferential wall portion which cooperate to partially define said annular groove;a coil disposed in said annular groove of said yoke member, said coil being energized by an electric current applied thereto so that a magnetic circuit is formed around said coil, and that said inner and outer circumferential wall portions of said yoke member are magnetized as respective opposite magnetic poles at open end portions thereof; andan oscillating member made of a magnetic material and disposed opposite to said one end face of said yoke member in an axial direction of said yoke member with a predetermined axial distance therebetween, said oscillating member having an inner and an outer circumferential portion which are located nearest to said open end portions of said inner and outer circumferential wall portions of said yoke member, respectively,said coil being energized for generating a magnetic force acting on said oscillating member so that an oscillating force is generated between said oscillating member and said yoke member in said axial direction,at least one of said open end portions of said inner and outer circumferential wall portions of said yoke member being directly opposed in said axial direction to said inner and/or outer circumferential portions of said oscillating member, while at least the other open end portion of said inner and outer circumferential wall portions of said yoke member having a first circumferential edge portion which is located nearest to a second circumferential edge portion of said inner and/or outer circumferential portions of said oscillating member, said first and second circumferential edge portions being offset from each other in a direction perpendicular to said axial direction, while being opposed to each other in a direction inclined with respect to said axial direction.