Prosthetic joint with dynamic torque compensator
First Claim
Patent Images
1. A constant torque joint comprising:
- first and second brace extensions;
a joint coupling said extensions together for angular rotation with respect to each other;
a cable extending from said joint, a part of said cable defining a moment art length; and
a spring attached to one end of said cable, said spring having defined spring performance characteristics;
said joint further comprising;
a pivot pin, a pulley pin, and an anchor pin, said cable being maintained in contact with said pivot pin and being at least partially wrapped around said pulley pin;
an arcuate slot in said joint capturing said pulley pin;
a cam slot and a radial slot each in said joint and capturing said anchor pin;
said arcuate and cam slots each being oriented in respective angles about a joint axis of said joint, a configuration of each said arcuate and cam slot being a function of said defined spring performance characteristics, said pulley pin maintaining a generally constant distance from said joint axis while travelling within said arcuate slot, a distance from said anchor pin to said joint axis corresponding to said moment arm length varying as said anchor pin travels within said cam and radial slots; and
another end of said cable being secured to said anchor pin, said cable being wrapped at least partially about said pivot and pulley pins so that upon rotation of said first and second extensions relative to each other said pulley pin travels within said arcuate slot and said anchor pin travels within said cam and radial slots to vary said moment arm length and compensate for vagaries of said defined spring performance characteristics and produce a constant torque in said joint and between said joint extensions throughout the full range of movement of said extensions with respect to each other.
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Abstract
A constant torque joint utilizes joint elements extending respectively between brace attachments for use in an anatomical brace. The brace has a range of motion dependent upon the particular application and in one embodiment from about 65° to about 215° with an included angle of motion of approximately 150°. A constant torque in the joint is provided by a spring-loaded cable wherein a cam driven cable anchor pin is utilized to compensate for variations in the spring cable joint system to produce a constant torque within the joint throughout the full range of motion of the joint.
78 Citations
29 Claims
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1. A constant torque joint comprising:
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first and second brace extensions; a joint coupling said extensions together for angular rotation with respect to each other; a cable extending from said joint, a part of said cable defining a moment art length; and a spring attached to one end of said cable, said spring having defined spring performance characteristics; said joint further comprising; a pivot pin, a pulley pin, and an anchor pin, said cable being maintained in contact with said pivot pin and being at least partially wrapped around said pulley pin; an arcuate slot in said joint capturing said pulley pin; a cam slot and a radial slot each in said joint and capturing said anchor pin; said arcuate and cam slots each being oriented in respective angles about a joint axis of said joint, a configuration of each said arcuate and cam slot being a function of said defined spring performance characteristics, said pulley pin maintaining a generally constant distance from said joint axis while travelling within said arcuate slot, a distance from said anchor pin to said joint axis corresponding to said moment arm length varying as said anchor pin travels within said cam and radial slots; and another end of said cable being secured to said anchor pin, said cable being wrapped at least partially about said pivot and pulley pins so that upon rotation of said first and second extensions relative to each other said pulley pin travels within said arcuate slot and said anchor pin travels within said cam and radial slots to vary said moment arm length and compensate for vagaries of said defined spring performance characteristics and produce a constant torque in said joint and between said joint extensions throughout the full range of movement of said extensions with respect to each other. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A joint to provide for constant torque pivotal movement between a pair of extensions, said joint comprising:
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a first and a second plate juxtapositioned to each other, one of the extensions projecting from each said plate; a cable extending from the joint, a part of said cable defining a moment arm length; a spring attached to one end of said cable, said spring having defined spring performance characteristics; a pivot pin, a pulley pin, and an anchor pin, said cable being maintained in contact with said pivot pin and being at least partially wrapped around said pulley pin; an arcuate slot in said first plate, said arcuate slot capturing said pulley pin; a cam slot in said first plate and a radial slot in said second plate, said cam and radial slots each capturing said anchor pin; said arcuate and cam slots each being oriented in respective angles about a joint axis of said joint, a configuration of each arcuate and cam slot being a function of said defined spring performance characteristics, said pulley pin maintaining a generally constant distance from said joint axis while travelling within said arcuate slot in response to movement of the extensions relative to each other, a distance from said anchor pin to said joint axis corresponding to said moment arm length varying as said anchor pin travels within said cam and radial slots in response to movement of the extensions relative to each other; and another end of said cable being secured to said anchor pin, said cable being wrapped at least partially about said pivot and pulley pins so that upon movement of the extensions relative to each other said pulley pin travels within said arcuate slot and said anchor pin travels within said cam and radial slots to vary said moment arm length and compensate for vagaries of said defined spring performance characteristics and produce a constant torque in the joint and between the extensions throughout the full range of movement of the extensions. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. A joint to provide for constant torque pivotal movement between a pair of extensions, said joint comprising:
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a cable extending from the joint; a spring attached to one end of said cable said spring being mounted between a movable abutment and a stop, said stop being fixed relative to one of said extensions, said one end of said cable being secured to said abutment; a pivot pin, a pulley pin, and an anchor pin, said cable being maintained in contact with said pivot pin and being at least partially wrapped around said pulley pin; an upper and a lower moving plate, said spring and said cable being positioned between said moving plates, each said moving plate having an arm extending from a generally circular portion, each said moving plate circular portion having an arcuate slot capturing said pulley pin, a cam slot capturing said anchor pin and a pivot aperture capturing said pivot pin, said arms of said upper and lower moving plates being aligned with each other to form one of the extensions; a bushing positioned between said upper and lower moving plates, said upper and lower moving plates being fixed with respect to each other and with respect to said bushing; an upper and a lower stationary plate, each said stationary plate having an arm extending from a generally circular portion, each said stationary plate having a radial slot capturing said anchor pin, said pulley pin being fixed relative to said stationary plates, said moving plates and said bushing being positioned between said stationary plates, said arms of said upper and lower stationary plates being aligned with each other to form the other of the extensions; said arcuate slots and said cam slots each being oriented in respective angles about a joint axis of the joint, said pulley pin maintaining a generally constant distance from said joint axis while travelling within said arcuate slots in response to movement of the extensions relative to each other, a distance from said anchor pin to said joint axis varying as said anchor pin travels within said cam and radial slots in response to movement of the extensions relative to each other; and another end of said cable being secured to said anchor pin, said cable being wrapped at least partially about said pivot and pulley pins so that upon;
movement of the extensions relative to each other said pulley pin travels within said arcuate slot and said anchor pin travels within said cam and radial slots to compress said spring and produce a constant torque in the joint and between the extensions throughout the full range of movement of the extensions. - View Dependent Claims (22, 23, 24, 25)
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26. A constant torque joint comprising;
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a joint having a pivot axis; a cable mounted in said joint for applying resistance to movement of said joint; a spring coupled to a first end of said cable; a cable anchor attached to a second end of said cable and movable within said joint as a function of a spring rate of said spring over a deflection range of said spring to provide a constant torque in response to movement of said joint; said cable having a moment arm length which varies with the movement of said cable anchor to compensate for vagaries of said spring; and an anchor pin captured in said joint, said moment arm length being defined by a position of said anchor pin relative to said pivot axis of said joint. - View Dependent Claims (27, 28)
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29. A constant torque joint comprising:
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a joint having a pivot axis; a cable mounted in said joint for applying resistance to movement of said joint; a tensioning apparatus for applying tension to said cable, said tensioning apparatus having a deflection range and a force rate; a cable anchor attached to said cable and movable within said joint as a function of said force rate over said deflection range of said tensioning apparatus to provide a constant torque in response to movement of said joint; said cable having a moment arm length which varies with the movement of said cable anchor to compensate for vagaries of said tensioning apparatus; and an anchor pin captured in said joint, said moment arm length being defined by a position of said anchor pin relative to said pivot axis of said joint.
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Specification