Energy harvester utilizing external magnetic field

• US 7,808,236 B1
• Filed: 01/11/2007
• Issued: 10/05/2010
• Est. Priority Date: 12/09/2002
• Status: Expired due to Fees

• Current Assignee: Ferro Solutions, Inc.
• Original Assignee: Ferro Solutions, Inc.
• Inventors: O'Handley, Robert C., Bono, David C., Huang, Jiankang
• Primary Examiner(s): LeDynh; Bot L
• Application Number:
  US11/652,272
• Publication Number:
  US 20100253089A1
• Time in Patent Office: 1,363 Days
• Field of Search: 324/109, 324/151.R, 324/244, 324/249, 324/260, 365/157, 737/79, 738/610.8, 738/617.7, 738/626.9
• US Class Current: 324/249
• CPC Class Codes: G01R 33/18 Measuring magnetostrictive properties
• CPC Class Codes: H10N 30/00 Piezoelectric or electrostrictive devices integrated devices or assemblies of multiple devices H10N39/00
• CPC Class Codes: H10N 35/00 Magnetostrictive devices integrated devices or assemblies of multiple devices H10N39/00

Abstract

Apparatus and method for harvesting energy from the environment and/or other external sources and converting it to useful electrical energy. The harvester does not contain a permanent magnet or other local field source but instead relies on the earth'"'"'s magnetic field of another source of a magnetic field that is external to the sensing device. One advantage of these new harvesters is that they can be made smaller and lighter than energy harvesters that contain a magnet and/or an inertial mass.

Claims

1. An energy harvester without a local field source comprising:

a magnetic field sensing element including one or more layers of magnetostrictive material having a magnetization vector that responds to variations in an applied magnetic field by generating a stress, and one or more layers of electroactive material, mechanically bonded to the layer of magnetostrictive material, that responds to the stress by generating a voltage; and

a circuit coupled to the sensing element that converts the voltage to electrical power for immediate use or storage;

wherein the sensing element is mounted to an object that moves relative to the applied magnetic field, such that changes in orientation of the sensing element with respect to the applied field generates the voltage.

2. The energy harvester of claim 1, wherein the sensing element includes electrodes for measuring the voltage generated and wherein the electrodes are configured such that the distance between the electrodes and cross sectional area between the electrodes are tailored to produce a desired electrical power;

and

wherein the magnetization vector rotates relative to the electrode axis due to changes in the orientation of the sensor in the applied external field.

3. The energy harvester of claim 2, wherein local vibrations also change the orientation of the sensor with respect to the applied external field.