Energy harvesting by means of thermo-mechanical device utilizing bistable ferromagnets

• US 7,800,278 B2
• Filed: 01/24/2007
• Issued: 09/21/2010
• Est. Priority Date: 01/25/2006
• Status: Expired due to Fees

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Ujihara, Motoki, Lee, Dong Gun, Carman, Gregory P.
• Primary Examiner(s): Tamai; Karl I
• Application Number:
  US12/162,082
• Publication Number:
  US 20090315335A1
• Time in Patent Office: 1,336 Days
• Field of Search: 310/306, 310/307, 310/339, 290/1.R, 605/27, 605/28
• US Class Current: 310/306
• CPC Class Codes: F03G 7/065 using a shape memory element
• CPC Class Codes: H02K 35/06 with moving flux distributors, and both coil systems and magnets stationary
• CPC Class Codes: H02N 2/18 producing electrical output from mechanical input, e.g. generators for measurement devices G01
• CPC Class Codes: H02N 3/00 Generators in which thermal or kinetic energy is converted into electrical energy by ionisation of a fluid and removal of the charge therefrom discharge tubes functioning as thermionic generators H01J45/00
• CPC Class Codes: H10N 30/304 Beam type
• CPC Class Codes: H10N 30/306 Cantilevers

Abstract

An inventive energy harvesting apparatus may include a ferromagnetic material and/or a shape memory alloys to convert thermal energy to mechanical energy to electrical energy. The apparatus is subjected to a thermal gradient to cause beams to bend thus creating stress/strain in a piezoelectric material, or creating magnetic flux in a magnetic path. The charges created in this process can be transferred to electrical batteries.

Claims

1. An energy harvesting device, comprising:

a ferromagnetic component suitable to be arranged between a heat source and a heat sink;

a mechanical assembly structured to support said ferromagnetic component in a first configuration such that said ferromagnetic component is in thermal contact with said heat source and in a second configuration such that said ferromagnetic component is in thermal contact with said heat sink, said mechanical assembly structured to have a transient state of motion due to said ferromagnetic component satisfying first and second conditions, namely a first condition when a temperature of a ferromagnetic material of said ferromagnetic component T is less than Tc, and a second condition when the temperature of the ferromagnetic material of said ferromagnetic component T is more than Tc,

wherein said mechanical assembly comprises an electromechanical transducer constructed and arranged to produce electrical power while said mechanical assembly is in said transient state of motion between said first and second configurations, and

wherein said mechanical assembly comprises a shape-memory component.

2. An energy harvesting device according to claim 1, wherein said ferromagnetic component comprises a ferromagnetic material having a Curie temperature that is less than a temperature of said heat source.

3. An energy harvesting device according to claim 2, wherein said mechanical assembly comprises a spring structure that is constructed and arranged to cause said ferromagnetic component to be restored to said second condition after said ferromagnetic component heats up to a temperature that is greater than said Curie temperature.

4. An energy harvesting device according to claim 1, wherein a material of said shape-memory component comprises a shape memory alloy having an Austenite phase transformation temperature that is higher than said Curie temperature of said ferromagnetic material such that said shape-memory component causes said mechanical assembly to move said ferromagnetic component through said transient state to said second configuration after being heated to at least said Austenite phase transformation temperature in said first configuration.

5. An electrical device, comprising:

an energy harvester; and

an electrically operable system electrically connected to said energy harvester to receive

electrical energy from said energy harvester,

wherein said energy harvester comprises;

a ferromagnetic component suitable to be arranged between a heat source and a heat sink;

a mechanical assembly structured to support said ferromagnetic component in a first configuration such that said ferromagnetic component is in thermal contact with said heat source and structured to support said ferromagnetic component in a second configuration such that said ferromagnetic component is in thermal contact with said heat sink, said mechanical assembly structured to have a transient state of motion between said first and second configurations,

wherein said mechanical assembly comprises an electromechanical transducer constructed and arranged to produce electrical power while said mechanical assembly is in said transient state of motion between said first and second configurations, and

wherein said mechanical assembly comprises a shape-memory component.

6. An electrical device according to claim 5, further comprising an electrical energy storage unit arrange in at least selective electrical connection with said energy harvester and said electrically operable system, said electrical energy storage unit being suitable to receive and store electrical energy from said energy harvester and to provide electrical energy to said electrically operable system.

7. An electrical device according to claim 5, wherein said electrically operable system comprises electronic components.

8. An electrical device according to claim 5, wherein said electrically operable system comprises a sensor.

9. An electrical device according to claim 7, wherein said electrically operable system comprises a communications unit.

10. An electrical device according to claim 6, wherein said electrical energy storage unit comprises a battery.

11. An electrical device according to claim 6, wherein said electrical energy storage unit comprises a capacitor.

12. A method of harvesting energy, comprising:

arranging an energy harvester having a ferromagnetic component between a heat source and a heat sink; and

receiving electrical energy output from said energy harvester,

wherein said ferromagnetic component is connected to a mechanical assembly having a first configuration such that said ferromagnetic component is in thermal contact with said heat source, a second configuration such that said ferromagnetic component is in thermal contact with said heat sink, and a transient state of motion between said first and second configurations,

wherein said mechanical assembly comprises an electromechanical transducer constructed and arranged to produce electrical power while said mechanical assembly is in said transient state of motion between said first and second configurations, and

wherein said mechanical assembly comprises a shape-memory component.