Passive joint device, cable guide, and power transmission mechanism
Inventors
Assignees
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Publication Number
US-11883953-B2
Publication Date
2024-01-30
Expiration Date
Abstract
A passive joint device for supporting a rotation-side member rotatably about a horizontal axis in a vertical direction with respect to a fixed-side member, includes: a cylindrical cam member having a pair of cam surfaces symmetrically arranged about a horizontal axis, a pedestal slidably disposed along the horizontal axis fixed to the rotation-side member, the pedestal having a pair of cam followers that contact with each of the pair of cam surfaces, a spring disposed inside the horizontal axis and biasing the pedestal toward the fixed-side member along the horizontal axis, wherein the spring force causes the pair of cam followers to come into contact with the pair of cam surfaces, and provide upward rotational force to the rotation-side member to reduce the downward rotational force of the rotation-side member.
Core Innovation
The disclosure relates to a passive joint device for supporting a rotation-side member rotatably about a horizontal axis in a vertical direction with respect to a fixed-side member. The device includes a cylindrical cam member fixed to the fixed-side member, where the cam member has a pair of cam surfaces symmetrically arranged on a cylindrical surface about the horizontal axis and formed obliquely along the horizontal axis.
A pedestal is slidably disposed along the horizontal axis within the horizontal axis fixed to the rotation-side member, and the pedestal has a pair of cam followers that contact with each of the pair of cam surfaces. A spring is disposed inside the horizontal axis fixed to the rotation-side member, and the spring biasing the pedestal toward the fixed-side member along the horizontal axis causes the pair of cam followers to come into contact with the pair of cam surfaces.
The spring force pushes the pair of cam surfaces and provides upward rotational force to the rotation-side member. The upward rotational force reduces the downward rotational force of the rotation-side member by the weight applied to the rotation-side member, thereby counteracting distal self-weight. The disclosure also provides a pipe-shaped cable guide device for routing a pair of cables, including arcuate cable guide surfaces that route the cables through the joint while accommodating relative motion between the fixed-side member and the rotation-side member.
Further, a power transmission mechanism uses worm gear(s) and a rotation operation member that rotates about an axis perpendicular to the passive joint axis, including an offset-shaft implementation where a second rotation shaft is offset from the horizontal axis to make the axis of rotation orthogonal to the horizontal axis.
Claims Coverage
The only independent claim identified is clm-00001. It is supported by multiple dependent claims that refine aspects of the cam-follower arrangement, pedestal sliding support, cam-surface geometry, cable guidance, and power transmission geometry.
Spring-biased pedestal with oblique symmetric cam surfaces for upward rotational force
A cylindrical cam member fixed to the fixed-side member has a pair of cam surfaces symmetrically arranged on the cylindrical surface about the horizontal axis and formed obliquely along the horizontal axis; a spring disposed inside the horizontal axis fixed to the rotation-side member biases a pedestal slidable along the horizontal axis toward the fixed-side member, so that spring force causes a pair of cam followers to come into contact with the pair of cam surfaces, push the pair of cam surfaces, and provide upward rotational force to the rotation-side member to reduce the downward rotational force by the weight applied to the rotation-side member.
Rotationally mounted cam followers at opposite ends of the pedestal
The cam followers are rotationally mounted at opposite ends of the pedestal.
Slide bearing support for pedestal sliding along the horizontal axis
A slide bearing is rotatably mounted on the pedestal and supports the pedestal slidably along the horizontal axis relative to the horizontal axis.
Curved cam surface matching spring displacement and load characteristics
A cam surface is made as a curved surface that matches the spring displacement and load characteristics.
Pipe-shaped cable guide with arcuate guide portions for a pair of cables
A guide member includes a pipe-shaped, horizontally axis-rotatable component that slidably guides a pair of cables and rotates about the horizontal axis as the cables move in the same direction due to relative rotation between the fixed-side member and the rotation-side member.
Orthogonal rotation operation member via offset second rotation shaft
The second rotation shaft is offset from the horizontal axis, making the rotation member’s axis of rotation orthogonal to the horizontal axis.
Overall, the claim set centers on a spring-biased, slidable pedestal with cam followers contacting an obliquely formed, symmetrically arranged cylindrical cam surface to generate upward rotational force that reduces the effect of the rotation-side member’s weight, with further refinements to cam-follower mounting, sliding support, cam-surface shaping, cable routing, and orthogonal power-transmission geometry.
Stated Advantages
Reduces the downward rotational force of the rotation-side member by the weight applied to the rotation-side member.
Documented Applications
Not explicitly described in patent.
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