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How to Make Inductor Cores More Efficient

Patent

EP2238601

Owner

OSRAM GmbH

Filing Date

November 24, 2008

Priority Date

January 31, 2008

Portfolio

Components - OSRAM

Intro

This invention proposes an new type of inductor core unit for an inductor in order to achieve a longer operating period of the inductor with low sound emission while tolerating temperature fluctuations. The patent is active in Germany and France. It has counterparts in the U.S., China, Korea and Taiwan.

Claims

1. Inductor having an electrical conductor for generating a magnetic field and having at least one inductor core unit (10) which is arranged in the re...
  1. Inductor having an electrical conductor for generating a magnetic field and having at least one inductor core unit (10) which is arranged in the region of the conductor and comprises an inductor core (12) composed of two inductor core parts (12a, 12b) composed of a magnetizable material and also at least one air gap (16), a filling material (18) being introduced at least into part of the air gap (16) for the purpose of mechanical stabilization, wherein the filling material (18) is embodied in such a way that it has a coefficient of thermal expansion (αF) which is increased between 10% and 50% in comparison with that of the magnetizable material of the inductor core, characterized in that the filling material comprises a water-hardened cement which, with addition of water, is present as a pasty composition which is introduced into a section (16b) of the air gap (16), and by means of compression of the two inductor core parts (12a, 12b), a force-locking connection is produced between the inductor core (12) and the coil former (14), such that an assembly that is particularly stable mechanically arises after the filling material (18) has cured.
  2. Inductor according to Claim 1, characterized in that the magnetizable material of which the inductor core (12) is composed comprises at least one type of ferrite and/or an iron powder and/or a molypermalloy powder and/or a nanocrystalline magnetic material.
  3. Inductor according to either of Claims 1 and 2, characterized in that the electrical conductor is wound, preferably multiply, onto a coil former (14).
  4. Inductor according to Claims 1 to 3, characterized in that the cement comprises a silicate, preferably zirconium silicate and/or sodium silicate and/or calcium silicate, and/or comprises an oxide, preferably silicon dioxide and/or magnesium oxide and/or aluminum oxide and/or iron oxide and/or calcium oxide, and/or comprises a hydroxide, preferably calcium hydroxide, and/or comprises a sulfate, preferably calcium sulfate and/or comprises a phosphate, preferably magnesium phosphate.
  5. Method for producing an inductor core unit (10) for an inductor, in which an inductor core (12) composed of two inductor core parts (12a, 12b) composed of a magnetizable material with at least one air gap (16) is provided and a filling material (18) is introduced at least into part of the air gap (16) for the purpose of mechanical stabilization, wherein a filling material (18) is chosen, the coefficient of thermal expansion (αF) is increased between 10% and 50% in comparison with that of the magnetizable material of the inductor core, characterized in that the filling material comprises a water-hardenable cement which, with addition of water, is present as a pasty composition which is introduced into a section (16b) of the air gap (16), and by means of compression of the two inductor core parts (12a, 12b), a force-locking connection is produced between the inductor core (12) and the coil former (14), such that an assembly that is particularly stable mechanically arises after the filling material 18 has cured.
  6. Method according to Claim 5, characterized in that at least one type of ferrite is used as magnetizable material for the inductor core (12).
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Abstract

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ElectronicComponents
May 30, 2018

This invention is related to a method for production of an inductor core unit for an inductor in order to achieve a longer operating period of the inductor with low sound emission while tolerating temperature fluctuations. To achieve mechanical stabilization of the inductor core prior art proposes filling materials (usually organic adhesives or silicones) in the air gaps having values of the coefficient of thermal expansion which are five to ten times higher than that of the inductor core material. This causes cracking in the filling material of the gap of the inductor core unit or in the magnetizable material of the inductor core, consequently reducing mechanical stability and amplifying sound emissions from inductor core unit. The invention proposes to use filling material ,whose value for the coefficient of thermal expansion lies in the range of ±70% of the value of the coefficient of thermal expansion of the magnetizable material of which the inductor core is made. The temperature fluctuations during operation then lead to a comparable temperature-dependent expansion behaviour of the inductor core, and of the filling material, such that no cracks or mechanical damage occur.
Applications: The proposed inductor can be used as a resonance, step-controller or lamp inductor for electronic ballasts.

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Tech 101
May 30, 2018

The patent discloses the fabrication of an inductor core unit. Currently for mechanical stabilization of inductor core a magnetizable filling material is introduced in air gap, which generates an audible sound due to high temperature and reduce stability of inductor core. Proposed inductors use filling material with a coefficient of thermal expansion in a range of ±70% of that of inductor core magnetizable material. Also, the filling material uses water hardened cement selected from group of inorganic binder such as silicate, hydroxide, sulfate and phosphate so that inductor core has high operating period and low sound emission.
Applications: The technology may be implemented in inductors, coils or chokes.
Companies: Any company that produces inductors could be interested.

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Buggi
March 07, 2018

This Patent is about producing high quality Transformers or chokes with an Ferrite core known as "E"-core or the like. Normally some kind of plastic or epoxy glue is used to glue the two parts of that "E" core together. This has the problem that the thermal expansion coefficient of the glue is much higher than that of the ceramic ferrite material of the "E"-core. This leads to cracks and an inconsistent air gap of the part over the lifetime. Sometimes this is mitigated ba using a very soft glue, on the other hand this leads to an inconsistent air gap due to the elasticity of the glue. The invention overcomes this by using a ceramic cement to glue the two "E"-core halfes together forming a very sturdy and long lasting part which has no crack issues over the lifetime. As the independent claim is fairly broad, this is a good and valuable patent. This applies also to the US patent, as the claim of the US patent is even broader than the European one. GoodIP: Thank you for your review, Buggi! :-)

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