Constant force actuator

A method for imparting a substantially constant force to an object, comprising:

• positioning a constant force actuator adjacent the object, the constant force actuator having first and second force transmitting members linearly movable relative to one another and having a movement control element located on at least one of said first and second force transmitting members, and further having a pair of linkage arms each having a first end pivotally connected to a respective one of said first and second force transmitting members and each having second ends pivotally interconnected and defining a pivotal linkage angularly movable from a retracted position to an extended force transmitting position, and a linkage arm movement control guide having a predetermined movement control geometry and having linkage moving engagement with said movement control element during a portion of the extension movement of said pivotal linkage from said retracted position to said extended position, said method comprising:
• initiating extension movement of said constant force actuator from said contracted position of said pivotal linkage by moving at least a first of said force transmitting members linearly toward said second force transmitting member and causing reaction of said movement control element with said linkage arm movement control guide and developing a linkage movement force oriented for extension movement of said pivotal linkage and developing a substantially constant linkage transmitting force;
• continuing extension movement of said constant force actuator by forcible interaction of said linkage arm movement control guide and said movement control element until a predetermined intermediate angular relation of said pivotal linkage has been reached and said linkage arm movement control guide and said movement control element have separated;
• further continuing said extension movement of said constant force actuator by further moving said first and second force transmitting members toward one another and applying linear force from said force transmitting members directly to said pair of linkage arms;
• and
• from the extended condition of said constant force actuator causing contracting movement thereof by relative linear movement of said force transmitting members away from one another, said force transmitting members inducing contracting movement of said pivotal linkage.

A substantially constant force actuator, comprising:

• a pair of force transmitting members disposed for relative linear movement;
• and
• a linkage in force receiving relation with said force transmitting members and having a force transmitting element movable by said linkage in a direction substantially perpendicular to said relative linear movement of said force transmitting members and disposed for force transmitting contact with an object,
• said linkage having at least one movement control guide of predetermined geometry in force reacting engagement with at least one of said force transmitting members and translating said relative linear movement of said force transmitting members to extension and contraction movement of said linkage and linear movement of said force transmitting element.

A substantially constant force actuator, comprising:

• a pair of force transmitting members linearly movable relative to one another from positions of predetermined maximum spacing to positions of predetermined minimum spacing;
• a linear force transmitting mechanism forcibly moving said force transmitting members linearly to and from said positions of predetermined maximum spacing and predetermined minimum spacing;
• a movement control element located on at least one of said pair of force transmitting members;
• at least one pair of linkage arms each having a first end and a second end, said first ends of said linkage arms being pivotally connected to respective ones of said force transmitting members and said second ends of said linkage arms being pivotally interconnected, said at least one pair of linkage arms being angularly positionable at a predetermined minimum angle with said force transmitting members at said predetermined maximum spacing and being positionable at a predetermined maximum angle with said force transmitting members at said predetermined minimum spacing;
• a linkage arm guide defined by at least one of said linkage arms and having linkage moving engagement with said movement control element during extension movement of said linkage arms from said predetermined minimum angle to a predetermined intermediate angle;
• and
• said force transmitting members transmitting linkage movement force directly to said first and second linkage arms during extension movement of said linkage arms from said predetermined intermediate angle to said predetermined maximum angle.

A constant force actuator mechanism, comprising;

• a pair of force transmitting members, at least one of which is linearly movable to establish relative positions of predetermined maximum and minimum spacing thereof;
• a linear force transmitting mechanism moving said at least one force transmitting member linearly to and from said positions of predetermined maximum and minimum spacing;
• at least one movement control element located on at least one of said pair of force transmitting members;
• at least two pairs of linkage arms, each linkage arm having a first end and a second end, said first ends of said linkage arms being pivotally connected to a respective one of said force transmitting members, said second ends of said linkage arms being pivotally interconnected, said pairs of linkage arms each having angulating movement and being angularly positionable from minimum angles with said force transmitting members at said predetermined maximum spacing to maximum angles with said force transmitting members at said predetermined minimum spacing;
• power energized tractor elements mounted to each of said pairs of linkage arms and disposed for force transmitting engagement with a surface for traction movement of said constant force mechanism along the surface;
• and
• at least one linkage arm actuator defined by at least one of said linkage arms and having linkage moving engagement with said movement control element during at least a portion of the angulating movement of said linkage arms from said predetermined minimum angle to said predetermined maximum angle.