Nut assembly using partial nuts to limit harmonic error
First Claim
1. A nut assembly for translating rotational motion of a lead screw, which has threads formed about a central axis, to substantially linear motion of a supporting structure while compensating for selected harmonic error associated with the lead screw, said nut assembly comprising:
- one or more arcuate partial nuts in a spaced-apart arrangement about the central axis, each said partial nut having an are length that minimizes thread contact while maintaining a grip on the lead screw, each said partial nut further having threads complimentary to the threads of the lead screw such that, when said one or more partial nuts are in engagement with the lead screw, the rotational motion of the lead screw is translated to motion of said one or more partial nuts along the central axis;
a nut housing enclosing said one or more partial nuts, said nut housing comprising at least two segments, each said segment aligned with the central axis such that an occurrence of the selected harmonic error causes at least one said segment to be angularly displaced relative to the central axis of the lead screw for averaging the motion of the one or more partial nuts along the central axis and compensating for the selected harmonic error so as to produce substantially linear motion; and
means for connecting said nut housing with the supporting structure to transmit the substantially linear motion of said nut housing to the supporting structure.
12 Assignments
0 Petitions
Accused Products
Abstract
A nut assembly intended for use with a lead screw in precision movement devices for compensating for harmonic error from the lead screw by utilizing one or more partial nuts which are opposed along an axis of the lead screw such that the partial nuts ride the lead screw independently. An averaging apparatus is used to hold the partial nuts such that as the partial nuts follow the harmonic error, the error is averaged through the averaging apparatus to compensate for the harmonic error allowing the resulting motion of the nuts to be substantially linear.
23 Citations
21 Claims
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1. A nut assembly for translating rotational motion of a lead screw, which has threads formed about a central axis, to substantially linear motion of a supporting structure while compensating for selected harmonic error associated with the lead screw, said nut assembly comprising:
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one or more arcuate partial nuts in a spaced-apart arrangement about the central axis, each said partial nut having an are length that minimizes thread contact while maintaining a grip on the lead screw, each said partial nut further having threads complimentary to the threads of the lead screw such that, when said one or more partial nuts are in engagement with the lead screw, the rotational motion of the lead screw is translated to motion of said one or more partial nuts along the central axis; a nut housing enclosing said one or more partial nuts, said nut housing comprising at least two segments, each said segment aligned with the central axis such that an occurrence of the selected harmonic error causes at least one said segment to be angularly displaced relative to the central axis of the lead screw for averaging the motion of the one or more partial nuts along the central axis and compensating for the selected harmonic error so as to produce substantially linear motion; and
means for connecting said nut housing with the supporting structure to transmit the substantially linear motion of said nut housing to the supporting structure. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A nut assembly for translating rotational motion of a lead screw, which has threads formed about a central axis, to substantially linear motion of a supporting structure while compensating for selected harmonic error associated with the lead screw, said nut assembly comprising
one or more partial nuts in a spaced arrangement about the central axis, and having complimentary threads to the threads of the lead screw such that, when in engagement with the lead screw, the rotational motion of the lead screw is translated to horizontal motion of the one or more partial nuts; -
ring member having a rigid annular ring structure to enclose said one or more partial nuts around said lead screw; connection means for securing said nut assembly to said supporting structure; and at least one flexible member connecting said ring member with the connection means, said at least one flexible member being adapted to allow angular motion while restricting axial motion between the ring member and the connection means, said at least one flexible member located relative to the one or more partial nuts such that horizontal motion of the one or more partial nuts is averaged by the at least one flexible member thereby propagating the substantially linear motion compensated for selected harmonic error to the supporting structure. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A nut assembly for compensating for harmonic error in a lead screw which has threads formed about a central axis, said nut assembly comprising
one or more partial nuts adapted to move independently of each other in a spaced arrangement about the central axis, and having threads complimentary to the threads of the lead screw such that, when in engagement with the lead screw, the rotational motion of the lead screw is translated to motion of said one or more partial nuts along the central axis; - and
a nut housing enclosing said one or more partial nuts said nut housing having a gimbal structure to support the one or more partial nuts and to compensate for the selected harmonic error such that said nut housing moves along the central axis with a substantially uniform motion. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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Specification