Fully immersed magnetic transformer with multiple condensing surfaces and method

• US 6,384,703 B1
• Filed: 12/11/2000
• Issued: 05/07/2002
• Est. Priority Date: 12/11/2000
• Status: Expired due to Fees

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Ramos, Sergio, Asbury, Victor O.
• Primary Examiner(s): Donovan, Lincoln
• Assistant Examiner(s): NGUYEN, TUYEN T
• Application Number:
  US09/734,959
• Time in Patent Office: 512 Days
• Field of Search: 336/58, 336/60, 336/61, 336/83, 336/179, 336/183
• US Class Current: 336/58
• CPC Class Codes: H01F 27/18 by evaporating liquids
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 50/10 using inductive coupling

Abstract

A sealed transformer for use in charging the batteries of an electric automobile includes a housing that contains the secondary windings, a core and a dielectric fluid. A removable primary winding coupler is inserted into the housing to complete a magnetic circuit. During operation of the magnetic circuit, heat is continuously generated by the primary and secondary windings and the core. The fluid undergoes a first phase change and boils as it absorbs the generated heat. The boiling fluid absorbs additional heat and undergoes a second phase change is it turns into a vapor. The heat of vaporization is released into thin windows formed in the transformer housing when the vapors contact the relatively cooler windows and re-condense into a liquid. A continuous cycle of boiling, vaporizing, and condensing occurs during operation of the transformer to cool the transformer and to improve the power density of the transformer.

Claims

1. A vapor cooled automobile charging transformer for use with a primary inductive charge coupler having a primary electric winding that attaches to a fixed power supply, comprising:

a housing having a through-slot for receiving the inductive charge coupler, the housing including multiple window surfaces and an interior and exterior;

a transformer secondary winding disposed in the housing interior;

a magnetic core disposed in the housing interior for completing a magnetic circuit through the primary and secondary windings, the secondary winding and core continuously generating heat during operation; and

a dielectric liquid retained within the housing interior and submersing the core and secondary windings, the dielectric liquid continuously absorbing the heat generated by the core and secondary windings, wherein some of the liquid first boils and then changes phase and vaporizes, whereby the vapors contact the windows and immediately cool, causing the vapors to condense to a liquid state, whereupon during the phase change from vapor to liquid, the heat of vaporization is released and conducted out of the housing.

2. The vapor cooled transformer of claim 1, wherein the dielectric liquid absorbs and releases heat during a dual phase change, the first phase change occurring when the fluid boils and the second phase change occurring when the vapors cool and re-condense into a liquid.

3. The vapor cooled transformer of claim 1, wherein the fluid remains at a constant pressure during operation of the transformer.

4. The vapor cooled transformer of claim 2, wherein the vapors return to a liquid state upon contacting one of the housing condensing windows.

5. The vapor cooled transformer of claim 4, wherein the exterior of the housing is cooled with a second fluid, thereby increasing a heat removal rate of the transformer.