Viscous clutch with return bore through rotor

A method for selective torque transmission, the method comprising:

• delivering a rotational input to a housing assembly that carries a reservoir;
• rotating the housing assembly on a rotationally fixed mounting shaft with a first bearing set, wherein the first bearing set is located radially inward from the reservoir;
• selectively delivering a shear fluid to a working chamber along a fluid delivery path extending from the reservoir to the working chamber, wherein the fluid delivery path extends through an outlet bore along a boundary of the reservoir;
• transmitting torque to a rotor assembly as a function of volume of the shear fluid selectively delivered to the working chamber;
• rotating the rotor assembly on the rotationally fixed mounting shaft with a second bearing set;
• and
• returning the shear fluid from the working chamber to the reservoir along a fluid return path that extends through a substantially radial bore through a disk of the rotor assembly.

A viscous clutch comprising:

• a housing assembly;
• a rotor assembly;
• a reservoir to hold a supply of a shear fluid;
• a working chamber operatively positioned between the housing assembly and the rotor assembly, wherein selective introduction of the shear fluid to the working chamber facilitates selective torque transmission between the housing assembly and the rotor assembly;
• a fluid return bore that extends radially through at least an outer diameter portion of the rotor assembly to the working chamber, the fluid return bore forming at least a portion of a fluid return path from the working chamber to the reservoir;
• an interchangeable pump bore insert positioned at least partially within the fluid return bore, wherein the inter-changeable pump bore insert includes a bore in fluid communication with the fluid return bore;
• and an access opening in the housing assembly configured to allow access to the interchangeable pump bore insert.

A viscous clutch comprising:

• a housing assembly;
• a rotor assembly including a disk;
• a reservoir to hold a supply of a shear fluid;
• a working chamber operatively positioned between the housing assembly and the rotor assembly, wherein selective introduction of the shear fluid to the working chamber facilitates selective torque transmission between the housing assembly and the rotor assembly;
• a fluid return bore that extends radially through at least an outer diameter portion of the rotor assembly to the working chamber, the fluid return bore forming at least a portion of a fluid return path from the working chamber to the reservoir;
• and
• a wiper at an outer diameter portion of the rotor assembly and protruding, at least partially, into the working chamber, wherein the wiper is removably attached to the disk of the rotor assembly.

A viscous clutch comprising:

• a rotationally fixed shaft;
• an input assembly rotationally mounted on the shaft;
• an output assembly rotationally mounted on the shaft, wherein the output assembly includes a disk and a bearing hub connected to the disk for co-rotation therewith, wherein the bearing hub extends beyond a front of the input assembly to provide a forward-facing mounting surface;
• a reservoir to hold a supply of a shear fluid, the reservoir carried by the input assembly;
• a reservoir cover attached to the input assembly, the reservoir cover defining a portion of a boundary of the reservoir;
• a working chamber operatively positioned between the input assembly and the disk of the output assembly;
• an outlet bore in the reservoir cover to allow the shear fluid out of the reservoir to the working chamber along a fluid delivery path;
• an additional outlet bore in the reservoir cover to further allow the shear fluid out of the reservoir to the working chamber along the fluid delivery path;
• an electromagnetically actuated valve assembly including:
• a first valve element that controls flow of the shear fluid between the reservoir and the working chamber through the outlet bore;
• a second valve element that further controls flow of the shear fluid between the reservoir and the working chamber through the additional outlet bore;
• a first axially-extending rod that passes through a first rod opening in the input assembly and that engages the first valve element;
• a second axially-extending rod that passes through a second rod opening in the input assembly and that engages the second valve element;
• and
• a translating armature located rearward of the disk and secured to both the first and second axially-extending rods, such that the first and second valve elements are actuatable concurrently in response to magnetic flux applied to the translating armature;
• and
• a fluid return bore that extends radially through at least an outer diameter portion of the disk of the output assembly to the working chamber, the fluid return bore forming at least a portion of a fluid return path from the working chamber to the reservoir.