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Method for overload protection of SMA device

An overload protection and overload technology, applied to emergency protection circuit devices, piezoelectric effect/electrostrictive or magnetostrictive motors, control generators, etc., can solve problems such as loss of recovery strain, excessive stretching of wires, etc.

Active Publication Date: 2015-05-20
GM GLOBAL TECH OPERATIONS LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the thermal properties of the SMA material, overload protection is expected to prevent excessive stretching of the wire and thus loss of ability to recover strain when activated

Method used

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  • Method for overload protection of SMA device
  • Method for overload protection of SMA device
  • Method for overload protection of SMA device

Examples

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Embodiment Construction

[0082] Referring now to the drawings, wherein these drawings are for purposes of illustration of certain exemplary embodiments only and not for purposes of limitation, Figure 1A and 1B A temperature-dependent phase diagram illustrating the critical stress for the austenite-martensite crystal transformation of shape memory alloys (SMAs). The axis of abscissa 1 represents temperature and the axis of ordinate 0 represents stress (σ). SMA has strong strain recoverable properties due to the crystalline transformation between martensite and austenite. As a result, SMAs are desirable because they can provide large shape changes or generate large forces.

[0083] figure 2 Roughly explains the stress (σ) and strain (ε) of a material. The axis of abscissa 6 represents strain (ε) and the axis of ordinate 0 represents stress (σ). As shown, the temperature-dependent strain recovers in a hysteresis loop upon heating 14 or upon unloading the material. This capability of reversible, co...

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PUM

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Abstract

A method for detecting a mechanical overload condition of an energized linear actuator to prevent commanding an activation signal to the linear actuator that may mechanically overload the linear actuator includes monitoring feedback variation of a movable element associated with the linear actuator including monitoring a present feedback signal of the movable element, monitoring a previous feedback signal of the movable element, comparing the present feedback signal and the previous feedback signal and determining the feedback variation based on the comparing. The feedback variation is compared to a feedback variation threshold. An input signal associated with the activation signal for controlling the linear actuator is monitored and the input signal compared to an input signal threshold. The electrical overload condition is detected when the feedback variation is less than the feedback variation threshold and the input signal is greater than the input signal threshold.

Description

[0001] Cross References to Related Applications [0002] This application claims the benefit of US Provisional Application No. 61 / 220,562, filed June 25, 2009, which is hereby incorporated by reference. technical field [0003] The present invention relates to detecting and preventing damage to electrified active materials from overload conditions. Background technique [0004] The statements in this section merely provide background information related to the present invention and may not constitute prior art. [0005] The active material provides the excitation (actuation) with relatively low cost and mass. Active materials may include shape memory alloys (SMA), electroactive polymers (EAP), piezoelectric, magnetostrictive and electrostrictive materials. Active materials are able to recover strain from an applied stress or load by applying a current through the active material, increasing the temperature or magnetic field of the active material. The ability to recover t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02P9/10H02H7/085
CPCH02N2/142H02N2/10
Inventor L·郝X·高S·M·奈克
Owner GM GLOBAL TECH OPERATIONS LLC