Morning sickness valve system for viscous clutch

A valve system for reducing morning sickness effects in a viscous clutch having a reservoir with a bore, the valve system comprising:

• a valve element;
• a counterweight portion;
• a pivot located in between the valve element and the counterweight portion, wherein the valve element and the counterweight portion are configured to commonly move about the pivot between open and closed positions;
• a biasing member configured to bias the valve element to cover the bore in the closed position by default, wherein the counterweight portion is configured to counteract the biasing member under centrifugal loading such that the valve element at least partially uncovers the bore in the open position;
• and
• a contacting member, wherein the valve element is configured to contact the contacting member when in the closed position, wherein the contacting member includes a cam.

A method for reducing morning sickness in a viscous clutch having an input member, an output member and a reservoir with a bore, the method comprising:

• biasing a valve element carried with the input member to cover the bore of the reservoir by default;
• pivoting the valve element to at least partially uncover the bore as a function of centrifugal loadings;
• and
• selectively actuating a primary valve assembly to cover the bore, wherein the primary valve assembly is positioned to cover a first end of the bore, and wherein the valve element is positioned to cover an opposite second end of the bore.

An assembly for a viscous clutch, the assembly comprising:

• a reservoir boundary wall having a bore that permits fluid flow, the bore having a first end and an opposite second end;
• a primary valve assembly controllable to selectively cover and uncover the bore at the first end to regulate fluid flow through the bore, wherein the primary valve assembly is biased to uncover the bore by default;
• and
• a morning sickness valve system moveable to cover and uncover the bore at the second end to reduce fluid flow at an idle condition, the morning sickness valve system being operable independent of the primary valve assembly,
• wherein the morning sickness valve system comprises:
• a valve element;
• a counterweight portion;
• a pivot located in between the valve element and the counterweight portion, wherein the valve element and the counterweight portion are configured to commonly move about the pivot between open and closed positions;
• and
• a biasing member configured to bias the valve element to cover the bore in the closed position by default, wherein the counterweight portion is configured to counteract the biasing member under centrifugal loading such that the valve element at least partially uncovers the bore in the open position.