Pump and wiper assembly, associated viscous clutch and associated method

A method of using a viscous clutch that includes a working chamber and a reservoir, wherein an output slip speed of the viscous clutch is controllable by varying a volume of a shear fluid present in the working chamber, the method comprising:

• partially shielding a first portion of the reservoir from a remaining portion of the reservoir with a wall;
• selectively controlling shear fluid flow from the reservoir to the working chamber through a release bore that is directly fluidically connected to the first portion of the reservoir;
• pumping the shear fluid from the working chamber to the reservoir with a leading wiper and a leading pump bore associated with the leading wiper, wherein the leading pump bore directly fluidically connects to the first portion of the reservoir;
• and
• pumping the shear fluid from the working chamber to the reservoir with a trailing wiper and a trailing pump bore associated with the trailing wiper, wherein the trailing pump bore directly fluidically connects to the first portion of the reservoir.

A viscous clutch comprising:

• an input member rotatable about an axis of rotation;
• an output member selectively rotatable about the axis of rotation;
• a working chamber bounded by the input member and the output member, wherein torque can be selectively transmitted between the input member and the output member through fluid frictional forces based upon a volume of a shear fluid present in the working chamber;
• a reservoir defining an interior volume capable of holding a supply of the shear fluid;
• a release bore that fluidically connects the reservoir to the working chamber;
• a leading wiper that extends into the working chamber;
• a leading pump bore positioned adjacent to the leading wiper, wherein the leading pump bore fluidically connects the working chamber to the reservoir;
• a trailing wiper that extends into the working chamber, wherein the trailing wiper has a width that is greater than a width of the leading wiper in an axial direction;
• and
• a trailing pump bore positioned adjacent to the trailing wiper and downstream of the leading pump bore, wherein the trailing pump bore fluidically connects the working chamber to the reservoir.