NO-BACK BRAKE FUNCTIONALITY MONITOR
First Claim
Patent Images
1. A no-back device for an actuator having a ball screw subject to an axially directed load, the no-back device comprising:
- a housing arranged to receive a portion of the ball screw, wherein the ball screw is mounted for rotation in first and second opposite rotational directions relative to the housing; and
a first brake mechanism responsive when the axial load is in a first load direction, the first brake mechanism acting between the housing and the ball screw to produce a first torque resisting rotation of the ball screw in the first rotational direction and not substantially resisting rotation of the ball screw in the second rotational direction, wherein the first brake mechanism includes a first ratchet wheel and a first pawl, the first pawl being pivotally mounted to the housing by a first pivot pin, wherein the first pawl engages the first ratchet wheel to prevent rotation of the first ratchet wheel relative to the housing when the ball screw rotates in the first rotational direction and the first pawl permits rotation of the first ratchet wheel relative to the housing when the ball screw rotates in the second rotational direction;
wherein the first pivot pin includes a first sensor generating a signal representative of the first torque produced by the first brake mechanism.
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Accused Products
Abstract
A no-back device usable in a Horizontal Stabilizer Trim Actuator (HSTA) includes a ratchet and pawl brake mechanism in which a pivot pin supporting the pawl includes a sensor for directly measuring torque developed by the brake mechanism. A signal generated by the sensor may be evaluated to determine the apparent operational integrity of the no-back device.
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Citations
16 Claims
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1. A no-back device for an actuator having a ball screw subject to an axially directed load, the no-back device comprising:
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a housing arranged to receive a portion of the ball screw, wherein the ball screw is mounted for rotation in first and second opposite rotational directions relative to the housing; and a first brake mechanism responsive when the axial load is in a first load direction, the first brake mechanism acting between the housing and the ball screw to produce a first torque resisting rotation of the ball screw in the first rotational direction and not substantially resisting rotation of the ball screw in the second rotational direction, wherein the first brake mechanism includes a first ratchet wheel and a first pawl, the first pawl being pivotally mounted to the housing by a first pivot pin, wherein the first pawl engages the first ratchet wheel to prevent rotation of the first ratchet wheel relative to the housing when the ball screw rotates in the first rotational direction and the first pawl permits rotation of the first ratchet wheel relative to the housing when the ball screw rotates in the second rotational direction; wherein the first pivot pin includes a first sensor generating a signal representative of the first torque produced by the first brake mechanism. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for testing operational integrity of a no-back device having a brake mechanism configured to apply a torque resisting rotation of a ball screw in a braked rotational direction and not substantially resisting rotation of the ball screw in a freewheeling rotational direction opposite the braked rotational direction, the method comprising:
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measuring the torque produced by the brake mechanism when the ball screw is rotated in the braked rotational direction, wherein the torque is measured using a sensor associated with a structural member of the brake mechanism, the sensor generating a braking torque signal representative of the torque produced by the brake mechanism when the ball screw is rotated in the braked rotational direction; and evaluating the braking torque signal to determine operational integrity of the no-back device. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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Specification