Patent ID: 8714939

Claim:
A water pump, comprising: a housing having a pumping chamber defined therein wherein the pumping chamber has an inlet and an outlet; a pumping mechanism disposed in the pumping chamber of the housing and configured to pump a fluid from the inlet to the outlet in response to a rotational force; a pulley for receiving an input torque; a clutch disk having a front side that faces the pulley and a rear side that faces the pumping mechanism, the clutch disk having an annular friction area on the front side thereof, wherein rotation of the clutch disk provides a rotational force to the pumping mechanism; a clutch ring connected to the pulley for rotation simultaneously therewith, the clutch ring fabricated at least in part from a ferromagnetic material wherein the clutch ring is moveable between a disengaged position, wherein an air gap is formed between the clutch ring and the clutch disk, and an engaged position, wherein the clutch ring engages the annular friction area of the clutch disk to rotate the clutch disk in unison with the clutch ring thereby providing the rotational force to the pumping mechanism in response to the input torque received by the pulley; a biasing element that is connected to the clutch ring and the pulley to bias the clutch ring toward the pulley to move the clutch ring toward the disengaged position; at least one magnet disposed on the clutch disk, wherein the at least one magnet exerts an attracting force on the clutch ring to attract the clutch ring toward the engaged position; and an electromagnetic coil operable to selectively produce an electromagnetic field that diminishes the attracting force exerted on the clutch ring by the at least one magnet to move the clutch ring between the engaged and disengaged positions, wherein the clutch ring is in the engaged position when the electromagnetic coil is de-energized, and the clutch ring is in the disengaged position when the electromagnetic coil is energized.