Viscous fluid clutch and reservoir by-pass valve therefor

A viscous fluid clutch comprising:

• a first member secured for rotation with a shaft;
• a second member rotatably disposed on said shaft relative to said first member;
• shear surfaces disposed on said first and second members and forming an operating chamber therebetween;
• a fluid storage chamber adjacent said operating chamber;
• pump means disposed radially distal said shaft and operative to displace fluid from said operating chamber radially inwardly to a return passage during relative rotation between said first and second members;
• and
• valve means disposed proximate the axis of said shaft and having a valving element selectively operable between a first position in which said return passage is in fluid communication with said fluid storage chamber and a second position in which said return passage is in fluid communication with said operating chamber said valving element being further operative to interrupt fluid flow from said fluid storage chamber to said operating chamber while in said first position and to establish fluid communication from said fluid storage chamber to said operating chamber while in said second position.

A viscous fluid clutch comprising:

• a clutch member secured for rotation with a shaft;
• a cover member rotatably disposed on said shaft relative to said clutch member;
• shear surface disposed on said clutch and cover members and forming an operating chamber therebetween;
• a reservoir cover affixed to said cover member adjacent said clutch member and defining a fluid storage chamber in combination with said cover member;
• at least one pump defined by adjacent portions of said clutch member and cover member radially distal siad shaft and operative to displace fluid from said operating chamber radially inwardly to a return passage during relative rotation between said clutch member and said cover member;
• and
• a valve disposed coaxially with said shaft and comprising,
• a pole piece disposed coaxially with said shaft and mounted for rotation with said cover member, said pole piece defining an axially aligned cavity which exits the end thereof nearest said reservoir cover and further comprises at least one substantially radially disposed port interconnecting said cavity with said return passage,
• a valving element comprising a spring and a by-pass tube, and displacable between a first position axially spaced from said pole piece wherein said return passage is in fluid communication with said fluid storage chamber and a second position in which said by-pass tube abutts the end of said pole piece wherein said return passage is in fluid communication with said operating chamber, a by-pass port defined by said tube registering with said cavity and opening into said operating chamber, said by-pass tube passing through an aperture in said reservoir cover in both said positions;
• said spring means biasing said valving element into said first position;
• and
• actuation means operative to displace said valving element from said first position to said second position.

A viscous fluid clutch comprising:

• a first member secured for rotation with a shaft;
• a second member rotatably disposed on said shaft relative to said first member;
• shear surfaces disposed on said first and second members and forming an operating chamber therebetween;
• a fluid storage chamber adjacent said operating chamber;
• pump means operative to displace fluid from said operating chamber to a return passage;
• a valving element selectively displaceable between a first position in which said return passage is in direct fluid communication with said fluid storage chamber and a second position in which said return passage is in direct fluid communication with said operating chamber;
• resilient means operative to bias said valving element into said first position;
• a solenoid disposed substantially coaxially with said shaft and operative to displace said valving element from said first position to said second position;
• and
• a pole piece coaxially mounted for rotation with said second member and defining a bearing surface supportive of said solenoid, said pole piece further defining an axially aligned cavity which exits the end thereof nearest said valving element, and at least one substantially radially disposed port interconnecting said cavity with said return passage.

A viscous fluid clutch comprising:

• a first member secured for rotation with a shaft;
• a second member rotatably disposed on said shaft relative to said first member;
• shear surfaces disposed on said first and second members and forming an operating chamber therebetween;
• a fluid storage chamber adjacent said operating chamber;
• pump means operative to displace fluid from said operating chamber to a return passage;
• and
• a valve blade disposed within said fluid storage chamber and selectively displaceable between a first position in which said return passage is in direct fluid communication with said fluid storage chamber and a second position in which said return passage is in direct fluid communication with said operating chamber, said valve blade operative to overlay drain ports interconnecting the radially outwardmost portion of said fluid storage chamber with said operating chamber when in said first position, thereby preventing fluid communication therebetween, said valve blade being further operative to uncover said drain ports in said second position, thereby permitting fluid communication between said fluid storage chamber and said operating chamber.

A viscous fluid clutch comprising:

• a first member secured for rotation with a shaft;
• a second member rotatably disposed on said shaft relative to said first member;
• shear surfaces disposed on said first and second members and forming an operating chamber therebetween;
• a fluid storage chamber adjacent said operating chamber;
• pump means operative to displace fluid from said operating chamber to a return passage;
• a valving element displaceable between a first position in which said return passage is in direct fluid communication with said fluid storage chamber and a second position in which said return passage is in direct fluid communication with said operating chamber;
• and
• resilient means operative to bias said valving element into said first position and comprising an elongated leaf spring disposed within said fluid storage chamber, at least one end of said leaf spring being secured to said second member, said spring being supportive of a valve blade affixed substantially normally thereto.