Patent ID: 7293636
Filing Date: 2007-11-13
Classification: F16D,Y10T

Abstract:
1. An electronically controlled viscous fan drive used on an internal combustion engine comprising: a cast output coupling member including a housing member coupled to a cover member; an actuator shaft partially disposed within said cast output coupling member; a cast input coupling assembly coupled to said actuator shaft and substantially contained within said cast output coupling member, said cast input coupling assembly capable of rotating at a given input speed, a reservoir cover coupled within said output coupling member and sealingly engaged to said cast input coupling member; a pair of cold pump out slots defined by said reservoir cover and said cast input coupling member; a fluid reservoir chamber defined by said reservoir cover and said cast input coupling member; a quantity of viscous fluid contained within said fluid reservoir chamber; a pair of fill holes, each of said pair of fill holes defined between a respective one of said pair of cold pump out slots and said fluid reservoir chamber; a fluid operating chamber defined by said cast input coupling member and said cover member, said fluid reservoir chamber fluidically coupled to said fluid operating chamber through said pair of cold pump out passageways, said fluid operating chamber further being fluidically coupled to said fluid reservoir chamber through a radial passage defined within said housing member; a valve disk coupled to said actuator shaft and disposed between said input coupling member and said reservoir cover, said valve disk being closely coupled with said pair of fill holes and controlling said amount of said viscous fluid entering said fluid operating chamber from said fluid reservoir chamber through said cold pump out passageways and through said pair of fill holes, wherein said amount of viscous fluid within said fluid operating chamber and said given input speed define an output rotational speed of said cast output coupling member; an actuator coupled around a portion of said actuator shaft, said actuator capable of axial movement along the length of said input coupling assembly in response to said magnetic flux to position said valve disk relative to said pair of fill holes between an engaged position, a partially engaged position, or in a disengaged position; a spring coupled along said actuator shaft and biasing said valve disk in a first position in the absence of said magnetic flux from said actuator, said first position selected from the group consisting of said engaged position and said disengaged position; wherein said engaged position is characterized such that said valve disk is positioned wherein said pair of fill holes are not covered by said valve disk, therein allowing maximum flow of said viscous fluid from said fluid reservoir chamber to said fluid operating chamber to drive said output coupling member at a maximum rotational speed at said given input speed; wherein said disengaged position is characterized is characterized such that said valve disk is positioned wherein said pair of fill holes are covered by said valve disk to prevent flow of said amount of viscous fluid from said fluid reservoir chamber to said fluid operating chamber; and wherein said partially engaged position is characterized such that said valve disk is positioned wherein said pair of fill holes are partially covered by said valve disk to allow a limited amount of said viscous fluid to flow from said fluid reservoir chamber to said fluid operating chamber to drive said output coupling member at a rotational speed less than said maximum rotational speed.