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Electrically activated surface mount thermal fuse

A technology of thermal fuse and activation state, which is applied in the direction of circuits, electric switches, electrical components, etc., and can solve the problem that the reflow oven cannot be installed on the circuit board, etc.

Active Publication Date: 2014-05-07
LITTELFUSE INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] One disadvantage of existing thermal fuses is that during installation of the thermal fuse, care must be taken to prevent the thermal fuse from reaching a temperature at which the sensing element changes state
As a result, existing thermal fuses cannot be mounted to circuit boards via reflow ovens operating at temperatures that would cause the sensing element to disconnect prematurely

Method used

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  • Electrically activated surface mount thermal fuse
  • Electrically activated surface mount thermal fuse
  • Electrically activated surface mount thermal fuse

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Embodiment Construction

[0023] To overcome the above problems, a reflowable thermal fuse is provided. Generally, the reflowable thermal fuse includes a conductive element through which a load current flows and a resilient element adapted to exert a force on the conductive element. In some embodiments, the conducting element is combined with the sensing element. When the temperature of the sensing element exceeds a threshold value, the sensing element loses its elasticity and becomes susceptible to deformation and / or rupture via the force exerted by the elastic element on the conducting element. Eventually, the conducting element breaks mechanically under this force, resulting in an open circuit state. In other embodiments, the sensing element and the conducting element are separate, and the sensing element is used to maintain the conducting element in a low resistance state.

[0024] During the reflow process, the sensing element loses its elasticity. In order to prevent the force exerted by the e...

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PUM

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Abstract

A reflowable thermal fuse includes a conduction element with first and second ends, disposed within a housing. The reflowable thermal fuse also includes an elastic element disposed within the housing and adapted to apply force on the conduction element in an activated state of the reflowable thermal fuse. A restraining element is utilized to secure the elastic element and prevent the elastic element from applying force on the conduction element in an installation state of the reflowable thermal fuse. Application of an activating current through the restraining element causes the restraining element to break and thereby release the elastic element and place the reflowable thermal fuse in the activated state.

Description

Technical field [0001] The present invention generally relates to electronic protection circuits. More specifically, the present invention relates to electrically activated surface mount thermal fuses. Background technique [0002] Protection circuits are often used in electronic circuits to isolate a faulty circuit from other circuits. For example, protection circuits can be used to prevent cascading failures of circuit modules in electric vehicle engine controllers. Protection circuits can also be used to prevent more serious problems, such as fires caused by power circuit failures. [0003] One type of protective circuit is a thermal fuse. Thermal fuses function in a manner similar to a typical glass tube fuse. That is, during normal operating conditions, the fuse acts like a short circuit, and during fault conditions, the fuse acts like an open circuit. The thermal fuse switches between these two modes of operation when its temperature exceeds a specified temperatur...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01H37/76
CPCH01H37/761H01H2037/046H01H2037/762H01H2037/763Y10T29/49107
Inventor 马太·P·加勒陈建华马丁·A·马太哈斯恩
Owner LITTELFUSE INC