Power generator

• US 9,935,255 B2
• Filed: 10/23/2014
• Issued: 04/03/2018
• Est. Priority Date: 10/25/2013
• Status: Expired due to Fees

• Current Assignee: Institut Polytechnique De Grenoble
• Original Assignee: Institut Polytechnique De Grenoble
• Inventors: Delamare, Jrome, Ricart, Thibault
• Primary Examiner(s): Lam, Thanh
• Application Number:
  US15/031,928
• Publication Number:
  US 20160276573A1
• Time in Patent Office: 1,258 Days
• Field of Search: 310 26, 310328
• CPC Class Codes: H02N 2/18 producing electrical output from mechanical input, e.g. generators for measurement devices G01
• CPC Class Codes: H02N 2/186 Vibration harvesters
• CPC Class Codes: H10N 30/00 Piezoelectric or electrostrictive devices integrated devices or assemblies of multiple devices H10N39/00
• CPC Class Codes: H10N 30/30 with mechanical input and electrical output, e.g. functioning as generators or sensors
• CPC Class Codes: H10N 35/101 with mechanical input and electrical output, e.g. generators, sensors

Abstract

A power generator including a converter with an electromechnical transducer and a magnetostrictive layer to convert a variation of a magnetic field into a mechanical deformation exerted on the transducer. There is a magnetic field source including a group of several permanent magnets. One of the group or the converter is movable, between first and second positions. The group has several first permanent magnets, one having an aspect ratio of between 1/10 and ten and most of the field lines that loop back do not pass through another first permanent magnet. The first permanent magnets are arranged such that the magnetic field induced inside the magnetostrictive material in the first position by one of the first permanent magnets is parallel to and in the direction opposite to the magnetic field induced at the same instant in the magnetostrictive material by the next first permanent.

Claims

1. A power generator comprising:

a converter able to convert a variation of a magnetic field into a difference of potentials between two electric terminals, the converter comprising to that effect;

an electromechnical transducer able to transform directly a mechanical deformation exerted on this electromechanical transducer into a difference of potentials between the two electric terminals, and

a magnetostrictive layer extending essentially parallel to a reference plane and fixed without any degree of freedom to the electromechnical transducer, the magnetostrictive layer comprising at least one block of magnetostrictive material able to convert a variation of the magnetic field into a mechanical deformation exerted on the electromechnical transducer,

a magnetic field source including a group of several permanent magnets aligned along an alignment axis, at least one of the group and the converter being movable, alternately, between;

a first position in which the field lines of the group of permanent magnets pass through the same block of magnetostrictive material and provoke a first deformation of this block of magnetostrictive material, and

a second position in which the block of magnetostrictive material has a second deformation different from the first deformation,

wherein the group of permanent magnets comprises a succession of first permanent magnets along the alignment axis, one first permanent magnet being a permanent magnet of the group, the first permanent magnet having the two following characteristics;

an aspect ratio, defined by the ratio of its thickness to its length in the direction of its magnetic moment, of between 1/10 and ten, and

most of the field lines that loop back by means of the block of magnetostrictive material and of the first permanent magnet in the first position do not pass through another first permanent magnet,

the first permanent magnets being arranged relative to one another such that the magnetic field induced inside the block of magnetostrictive material in the first position by any one of the first permanent magnets is parallel to and in the direction opposite to the magnetic field induced at the same instant in the same block by the first permanent magnet that follows immediately afterwards along the alignment axis.

2. The generator as claimed in claim 1, wherein each first permanent magnet has a magnetic moment parallel to the alignment axis and in the opposite direction to the direction of the magnetic moment of the first permanent magnet that follows immediately afterwards in said succession of first permanent magnets.

3. The generator as claimed in claim 2, wherein the group further comprises at least one second permanent magnet placed immediately next to one of the first permanent magnets, the magnetic moment of this second permanent magnet being perpendicular to the reference plane and its direction being the same as that of the field lines that pass through the block of magnetostrictive material and the first permanent magnet next to which it is immediately placed.

4. The generator as claimed in claim 3, wherein the length of the second permanent magnet in the direction of its magnetic moment is longer than or equal to the thickness, in the direction perpendicular to the reference plane, of the first permanent magnet next to which it is immediately placed, and the thickness of the second permanent magnet in a direction parallel to the alignment axis is at least two times smaller than the length of the first permanent magnet next to which it is immediately placed.

5. The generator as claimed in claim 2, wherein the magnetic field source comprises at least one magnetic tooth, made of soft magnetic material, directly placed next to one of the first permanent magnets in the direction of the alignment axis.

6. The generator as claimed in claim 1, wherein the amplitude of the vectorial summation of the magnetic moments of the group of permanent magnets equals zero plus or minus ∈

where ∈

equals 10% of the sum of the amplitudes of the magnetic moments of the permanent magnets of the group.

7. The generator as claimed in claim 1, wherein the magnetic field source comprises a second group of permanent magnets, symmetrical to the first group of permanent magnets relative to a plane parallel to the reference plane and passing at mid-height of the block of magnetostrictive material.

8. The generator as claimed in claim 1, wherein the converter is situated on one side of the group of permanent magnets and the generator comprises another converter placed on the opposite side relative to the group of permanent magnets, the two converters being symmetrical to one another relative to a median plane of the group of permanent magnets containing the alignment axis of this group.

9. The generator as claimed in claim 1, wherein the converter is situated on one side of the group of permanent magnets and the generator comprises a plate of magnetically soft material placed on the opposite side relative to the group of permanent magnets.

10. The generator as claimed in claim 1, wherein the aspect ratio of the first permanent magnets is more than or equal to 0.2 and less than or equal to 5.

11. The generator as claimed in claim 1, wherein the aspect ratio of the first permanent magnets is more than or equal to 0.5 and less than or equal to 2.

12. The generator as claimed in claim 1, wherein the permanent magnets of the group are fixed without any degree of freedom to one another and at least one of the group and the converter is movable, alternately, between:

the first position in which the block of magnetostrictive material is opposite the group of permanent magnets, and

the second position in which the block of magnetostrictive material is offset relative to the group of permanent magnets.