Viscous clutch with controlled drain back
AssigneesBehr America, Inc., Behr Industry America, L.P.
InventorsDavid L. McDermott, Joseph G. Sawyer
Life of this patent
Estimating the term…
Abstract
A viscous fluid clutch for controlling the rotation of an engine cooling fan has a dividing disk separating a storage chamber from a working chamber. The dividing disk includes an opening having a geometry that defines a drain-back path to the working chamber regardless of the angular orientation of the clutch.
Claims18
A viscous fluid clutch for a fan assembly, said viscous fluid clutch being movable between an engaged position and a released position, said viscous fluid clutch comprising:
- a clutch input portion;
- a clutch output portion rotatably supported with respect to said clutch input portion, said clutch output portion being adapted to transfer torque to said fan assembly, said clutch output portion cooperating with said clutch input portion to defining a working area;
- a viscous fluid disposed within said working area when said viscous fluid clutch is in said engaged position, said clutch input portion transmitting driving torque to said clutch output portion by shearing said viscous fluid within said working area when said viscous fluid clutch is in said engaged position;
- and
- a drain-back mechanism defining at least a portion of a viscous fluid storage chamber, said drain-back mechanism disposed to permit viscous fluid flow from said storage chamber to said working area, wherein the viscous fluid flow is a selected amount, and permit substantially the same amount of viscous fluid to flow from said storage chamber to said working area when said viscous fluid clutch is in said released position regardless of the angular orientation of said viscous fluid clutch.
A dividing disk for use in an electro-viscous fluid clutch operable in an on condition and an off condition, said viscous fluid clutch including a storage chamber for storing viscous fluid and a working chamber for providing a clutch coupling when a selected amount of viscous fluid is resident therein and the electro-viscous clutch is in the on condition, said dividing disk comprising:
- a disk body including a rim portion disposed for fixed attachment to said clutch and a depressed portion, disposed radially inwardly from said rim portion, for at least partially defining said storage chamber;
- and
- an opening centrally located within said depressed portion of the dividing disk disposed to permit viscous fluid flow from said storage chamber to said working area, wherein the viscous fluid flow is a selected amount, and permit substantially the same amount of viscous fluid to flow from said storage chamber to said working chamber when said viscous fluid clutch is in an off state regardless of the angular orientation of said dividing disk.
A method for making a rotatable viscous clutch assembly for an engine of a vehicle which has an inoperative condition, a start-up condition, and an operative condition, the clutch assembly including an input section, an output section, a viscous fluid storage chamber, and a working chamber disposed to contain viscous fluid for selectively engaging said input section with said output section when the vehicle is in the operative condition, the method comprising the steps of:
- determining a selected volume of viscous fluid required to be present in the working chamber for engaging the input section with the output section when the vehicle is in the start-up condition;
- developing a contour for a flow path between the storage chamber and the working chamber in a plurality of angular orientations of the viscous clutch assembly such that an amount of viscous fluid will drain back from the storage chamber to the working chamber thereby providing the selected volume of viscous fluid such that substantially the same volume of viscous fluid is in the working chamber when the vehicle is in the inoperative condition;
- and
- creating the flow path between the storage chamber and the working chamber based on said contour.
Dependencies are inferred from the claim text.