JP5855090B2 - A device that harvests power from mechanical energy - Google Patents

Description

  This invention was made with government support under US license number WC133R10CN0220 awarded by the National Oceanic and Atmospheric Administration. The government has certain rights in the invention.

This application claims the benefit of US Provisional Patent Application No. 61 / 328,396, filed April 27, 2010 under the name “Mechanical Energy Harvester Method and Device”. This provisional patent application is hereby incorporated by reference in its entirety. This application also claims the benefit of the priority of US Patent Application No. 13 / 016,895, filed January 28, 2011 under the name “Apparatus for Harvesting Electrical Power from Mechanical Energy”. This application also claims the benefit of the priority of US Patent Application No. 13 / 016,828, filed January 28, 2011 under the name “Wave Energy Harvester with Improved Performance”.

  The extensive development of renewable energy sources that are commercially viable and environmentally friendly is one of today's major global challenges. Such technologies can spur economic growth and contribute to the maintenance of a global environment and reduce our dependence on fossil fuels that can be depleted within decades. Ocean energy and other renewable energy sources have very high potential but are not fully utilized as clean energy sources to achieve these objectives.

  The Energy Information Bureau estimates that global electricity consumption will increase from 18 trillion to 32 trillion kWh between 2006 and 2030, with an annual growth rate of 2.4%. Of this global increase, 42% is expected to be supplied by coal, 24% by renewable energy, 23% by natural gas, and the rest by nuclear power. US electricity consumption will increase at a much lower rate, increasing from 4.1 trillion to 5.2 trillion kWh over this period. Of this domestic increase, 39% is expected to be supplied by coal, 32% by renewable energy and 18% by natural gas. Most of the contributions from renewable energy are expected to come from hydropower that is newer than renewables that do not harm the environment.

  The selection and development of new power generation technologies that are cost effective and energy efficient and environmentally friendly will bring economic, health and safety benefits to people in the United States and around the world. Since clean energy generation technologies are generally based on local resources, these technologies are useful for revitalizing local economies in coastal areas through job creation and revitalizing local industries through the use of inexpensive energy.

  Estimating the next 20 years rapidly, the increase in market share in the clean energy sector may be dominated by energy sources with high capital efficiency, cost effectiveness and resource availability. For example, traditional approaches to harvesting ocean energy do not meet these three criteria, these technologies require too much capital, are not competitive in energy costs, require very specific marine environments, and many Limit the possible locations and impact scale. Therefore, a normal ocean energy system cannot regard wind power generation, solar cells, solar power generation and geothermal power generation as equivalent.

  The power generation cost of the conventional device is estimated to be 3-5 times that of coal power generation. It seems reasonable that marine energy will never become an important part of global energy without fundamental departure from traditional approaches attempted to date.

  Embodiments of the apparatus are described. In one embodiment, the device is a device that harvests power from mechanical energy. The energy harvesting device includes a magnetic path. The magnetic path includes a magnetic material having a magnetic property that is a function of stress applied to itself, a first magnetic conducting material adjacent to the magnetic material, and a magnet that is located in the magnetic path and generates a magnetic flux by its magnetomotive force. And a component configured to transmit a load change caused by an external source to the magnetic material.

  Another embodiment of the device is described. In one embodiment, the device is a device that harvests power from mechanical energy. The apparatus includes one substantially closed magnetic path. The magnetic path includes a magnetic material having a magnetic characteristic that changes according to stress, a magnetic conductive material, and a permanent magnet located in the magnetic path. The apparatus further includes a component configured to transmit a load change caused by an external source to the magnetic material and at least one other component used to prestress the magnetic material. . Other embodiments of the device are also described.

  A method embodiment is also described. In one embodiment, the method is a method of harvesting power from mechanical energy. The method includes changing a magnetic property of the magnetic material as a function of stress applied to the magnetic material by a component configured to transmit a change in load from an external source to the magnetic material, substantially free of voids. Changing the magnetic flux by a magnetic force supplied by at least one permanent magnet located in a closed magnetic path, and conducting disposed relative to the magnetic path in response to the change in the magnetic flux in the magnetic material. Inducing a voltage in the coil.

  Other aspects and advantages of embodiments of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrated by way of example of the principles of the invention.

The graph figure of an example of the relationship between the electric power density of magnetostriction iron-aluminum alloy material, the load applied to this material, the application of this mechanical load, and an open frequency is shown. 1 shows a schematic diagram of one embodiment of an energy harvesting device. FIG. 2 shows a computer modeled schematic diagram of an example of a magnetic path of a magnetic material in a load application device. FIG. 2 shows a computer modeled schematic diagram of an example of a magnetic path of a magnetic material in a load application device. It is a graph which shows the magnitude | size of the magnetic flux density of the magnetic path of FIG. It is a graph which shows the magnitude | size of the magnetic flux density of the magnetic path of FIG. 1 shows a schematic diagram of one embodiment of an energy harvesting device. 1 shows a schematic diagram of one embodiment of an energy harvesting device. 1 shows a schematic diagram of one embodiment of an energy harvesting device. FIG. 4 shows a flowchart diagram of one embodiment of harvesting power from mechanical energy.

It will be readily appreciated that the components of the embodiments generally described and shown in the accompanying drawings can be arranged and designed in a variety of different configurations. Accordingly, the following detailed description of the various embodiments shown in the figures is not intended to limit the scope of the invention, but merely illustrates various embodiments. While various aspects of various embodiments are illustrated, the drawings are not necessarily drawn to scale except if specifically noted.

  The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. The disclosed embodiments are to be considered in all respects only as illustrative and not restrictive. Accordingly, the scope of the invention will be determined by the appended claims rather than by the detailed description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within the scope of the invention.

  Throughout this specification, references to features, advantages, or similar language do not imply that all of the features and advantages that can be realized with the present invention are present in any one embodiment of the present invention. Rather, reference to features and advantages should be understood to mean that a particular feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the invention. Accordingly, discussion of features and advantages or similar terms throughout this specification are not necessarily so, but relate to the same embodiment.

  Furthermore, the disclosed features, advantages, and characteristics of the invention may be combined in any suitable manner in one or more embodiments. Those skilled in the art will appreciate that the invention can be practiced without one or more of the specific features or advantages of a particular embodiment in light of the description herein. In other cases, certain features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the invention.

  Throughout this specification, references to “one embodiment,” “an embodiment,” or similar language refer to particular features, structures, or characteristics described in connection with a given embodiment. It is meant to be included in one embodiment. Thus, throughout this specification, “in one embodiment”, “an embodiment” or similar language, although not necessarily, all relate to the same embodiment.

  Although many embodiments are described herein, at least some of the described embodiments present a method and apparatus for harvesting power from mechanical energy. In particular, some embodiments comprise a magnetic material having a magnetic property that is a function of the stress applied to it, using a component that transmits load changes caused by an external source to the magnetic material. Can be operated. At this time, current or voltage can be generated by utilizing the change in the magnetic characteristics. In some embodiments, a magnet is placed proximate to the magnetic material or load transfer component to change the magnetic properties of the magnetic material.

  At least some of the embodiments present a method and apparatus for harvesting power from mechanical energy, the method and apparatus including a magnetic path that has a magnetic property that is a function of the weight applied to it. A magnetic material having at least one magnetic material proximate to the at least one magnetic material, a magnet located in a magnetic path and generating a magnetic flux in the magnetic material through the at least one magnetic material with its magnetomotive force; and Including at least one component configured to transmit a change in load caused by an external source to the magnetic material.

  As used herein, “magnetic material” is widely understood to include materials generally known to have specific magnetic properties, such as magnetostrictive materials, piezomagnetic materials, etc., but does not include permanent magnet materials. .

  One embodiment of the energy harvesting device comprises at least one magnetically conductive material having a relative permeability greater than 100, at least one magnet, and at least one magnetic material having at least one magnetic property that is a function of applied stress. The magnetic material is designed to transmit a mechanical load or vibration at a non-zero frequency. The magnet can be a permanent magnet or an electromagnet and can provide a bias magnetic field to the magnetic material. The magnet can pass a portion of the magnetic flux through the conductive material.

  In some embodiments of the device, one particular property that changes with stress in the magnetic material is permeability. In another embodiment, the particular property that changes with stress is saturation magnetization. In one embodiment of the device, there are no air gaps in the magnetic path. In another embodiment of the apparatus, the magnetic material is a magnetostrictive material. In another embodiment of the apparatus, the magnetic material is prestressed when no external force is acting on the magnetic material, and this force partially prestresses when an external force is applied. Try to overcome or join it. In another embodiment of the device, the magnetic material is brought to a high compressive stress state, typically above 1000 psi, and in some embodiments, above 5000 psi.

  The apparatus can also include a conductive coil, such as a copper coil, configured such that a change in magnetic flux through the magnetic material induces a voltage and / or current in the coil. The type of coil and the particular configuration do not limit the scope of the invention. The coil can be insulated to prevent current from flowing to other conductive materials and / or to protect the coil from the environment in which the energy harvesting device is used. In addition, the apparatus can include various components and structures designed to transmit or carry directly or indirectly mechanically coupled loads to the magnetic material. In some embodiments, one or more of the devices may be electrically connected to increase the electrical energy harvested for a particular application or to provide various different amounts of energy in one application. They can be connected in series or in parallel.

  A potential advantage of one embodiment of the energy harvesting device is that it can harvest power without requiring significant movement of any component of the device.

  Embodiments of the present invention also cover methods for harvesting and / or generating power using the devices described herein. Various uses of such devices are also described, and the specific use of such devices is not intended to limit the scope of the invention in any way. Certain embodiments of the device are those that can be used to harvest energy from ocean waves, wind, structural elements, mechanical elements and / or vibration elements.

  Various methods and devices include the principles described herein for prestressing and holding magnetic materials, such as mechanical loading by loading devices and mechanical clamping, thermal expansion based techniques, and prestressing during material processing. Although it can implement, it is not limited to this.

  In some embodiments, the magnetic material is a metal alloy. In some embodiments, the magnetic material is an iron-based alloy. In some embodiments, the iron-based alloy can contain other elements, including but not limited to aluminum, cobalt, chromium, gallium, silicon, molybdenum, tungsten, and beryllium. . In some embodiments, the magnetic material can be a terbium-based, nickel-based or cobalt-based material.

The magnetic material of the magnetostrictive device can be selected to increase the efficiency of the energy harvesting device. Possible criteria may be as follows:
1. For high energy efficiency, a material having a high differential coefficient of magnetization with respect to stress can be used. In other words, a small change in stress causes a large change in magnetization intensity.
2. The magnetic material may have a low strain-magnetization curve hysteresis. Low hysteresis results in low magnetomechanical coupling loss and improved energy efficiency.
3. The magnetic material may have a high internal resistance. The high internal resistance of the alloy results in minimization of energy loss due to eddy currents in the magnetostrictive component and the resulting heat generation.
4). The magnetic material can be of very low cost (cent / kWh) and the use of expensive exotic / rare alloy elements can be avoided.
5). The magnetic material can be of low weight (cent / kg) to reduce installation costs and / or maintenance costs.

  With these and other possible criteria, a larger efficiency and / or lower cost energy harvesting device can be configured according to the individual implementation of the device. Other criteria can be used for alternative or other embodiments using piezomagnetic materials.

  In some embodiments of the device, a change in load applied to the magnetic material produces a flux density change greater than 0.05 Tesla. In some embodiments of the device, changes in magnetic flux density greater than 0.3 Tesla can be obtained. In addition to the maximum change in magnetic material magnetic flux density, other important parameters can determine the power generation efficiency as a function of system size and cost.

  FIG. 1 shows the relationship between the power density (watts / kilogram) of a magnetostrictive iron-aluminum alloy material and the load 104 applied to the magnetic material and the frequency 106 at which the mechanical load is applied and released in the device configuration described herein. An example graph diagram of 100 is shown.

  To demonstrate certain embodiments of the energy harvesting device described herein, the generation of energy is demonstrated using a magnetostrictive material configured with a bias magnetic field and the ability to vary the load 104 applied to the magnetostrictive material. An experiment was conducted. However, in other embodiments, one or more features may be varied from the embodiments described herein. The basic components of the energy harvesting apparatus of this embodiment include a force generator for applying a compressive force, a tensile force, or a combination of a compressive force and a tensile force to the magnetostrictive element.

  In addition, a bias magnetic field can be applied to the magnetostrictive material. This is a continuous magnetic path that uses a magnet together with a magnetically conductive material (ie, mild steel, iron, electric furnace steel, etc.) to return from the north pole of the magnet through the magnetically conductive material and the magnetostrictive element to the south pole of the magnet. Is generated by configuring.

  Energy generation is achieved by changing the magnetic properties of the magnetostrictive element by changing the state of the load 104, resulting in a change in the magnetic flux through the magnetostrictive element. In one embodiment, the change in magnetic flux over time generates power through the use of a copper coil surrounding the magnetostrictive element.

  FIG. 2 shows a schematic diagram of one embodiment of an energy harvesting device 200. Although the magnetic material 205 is shown and described with the load applicator 210 of FIG. 2, other embodiments of the magnetic material 205 or load applier 210 may have fewer or more to achieve smaller or greater functionality. The components can be included. Device 200, including both magnetic material 205 and load applicator 210, can be used in a variety of energy harvesting structures or devices. For example, an energy harvesting device 200 as described herein can be used with a wave energy harvesting device. Such energy harvesting structures can include one or multiple energy harvesting devices in series or in parallel.

  In the embodiment of FIG. 2, the magnetostrictive element having the magnetic material 205 is a cylindrical rod that is 6 inches long and 1 inch in diameter. The magnetostrictive element includes a magnetic material 205 as described herein. A cylindrical rod can be surrounded by a conductive coil (not shown). In one embodiment, the coil consists of 180 turns of 14 AWG wire. In one embodiment, rectangular mild steel bars 212, 214 having dimensions of 1.5 inches long by 0.75 inches wide and 10 inches long are disposed at each end of the magnetostrictive rod. One or more magnets 216 are disposed at one or both ends of the rectangular mild steel bars 212, 214. The device 200 can also use a magnetically conductive material such as mild steel at each end of the magnetostrictive rod to connect the magnetic path of the magnet 216 of the upper bar 212 with the magnet 216 of the lower bar 214. This can be done by placing another rectangular bar 218 of similar dimensions in the vertical plane and in contact with both the magnet 216 at the end of the upper bar 212 and the magnet 216 at the end of the lower bar 214. . The resulting structure creates a closed loop magnetic path that passes through the magnetic material 205 along with the magnet 216 and the magnetically conductive materials 212, 214, 218. Other shapes and types of magnetically conductive materials can be used and are not limited to those disclosed herein.

  3 and 4 are computer model images 300 and 400 (using Vizimag software) of the magnetic path 305 of the magnetic material 205 in the energy harvesting apparatus 200. FIG. The magnetic material can include a magnetostrictive material. In this embodiment, the energy harvesting device 200 has two magnetic conducting bars 212, 214 at each end of the magnetostrictive rod. Further, a magnet 216 is disposed at each end of the magnetic conducting bars 212, 214 so that the additional magnetic conducting bar 218 contacts the magnets 216 at both ends of the upper and lower bars 212, 214 in contact with the magnetostrictive rod. Be placed. Thus, the upper and lower bars 212, 214 with magnet 216 and the left bar 218 form a closed loop through which about half of the magnetic flux can pass, and the upper and lower bars 212, 214 with magnet 216 and the right bar 310 have Another closed loop is formed that can pass about half of the magnetic path 305.

  The magnetic path 305 passes through the closed loop magnetic path in the two mechanical stress load states shown in FIGS. 3 and 4. In order to generate electric power, the magnetic flux 305 is changed by changing a stress state or a load of mechanical force applied to the magnetic material 205. FIG. 3 shows magnetic flux lines 305 when the stress state applied to the magnetostrictive rod results in a high magnetic permeability state. When the magnetic material 205 has a high magnetic permeability due to stress, most of the magnetic flux passes through the magnetic material 205. FIG. 4 shows a computer model image of the magnetic flux 305 when the stress state applied to the magnetic material 205 in the rod produces a low permeability state. Contrary to the high permeability state of FIG. 3, when the material 205 is in a low permeability state, much of the flux lines 305 pass outside the material and return to the other pole of the magnet. 5 and 6 show graphs 500 and 600 of the magnetic flux magnitude 505 in the corresponding magnetic flux states of FIGS. 3 and 4, respectively.

  Because the amount of magnetic flux that passes through the magnetostrictive rod changes relative to the stress condition imparted to the magnetic material 205 by the load transfer component 210, the conductive coil wound around the rod and connected to the electrical circuit changes the magnetic flux 305 that passes through the coil. Along with this, current starts to flow. The amount of voltage generated in the coil is a function of the amount of magnetic flux change through the coil and the number of turns of the coil. A high number of turns generates a high voltage. In some embodiments, the conductive coil can be a copper wire coil. In other embodiments, the conductor coil can include one or more conductive materials, such as copper or other conductive materials.

  In one embodiment of the apparatus 200 described herein comprising a magnetostrictive rod having dimensions and conductive coils as in FIG. 2, a load experiment was performed, a 16,000 pound compression load was applied to the magnetostriction rod, and then a zero compression load. Released to the state. The change in the load 104 applied to the magnetostrictive rod caused a change in the magnetic flux 305 passing through the magnetostrictive rod, and the magnetic path 305 passing through the energy harvesting device 200 was also changed. The resulting change in magnetic flux 305 generated a voltage of 0.48 volts and a current of 1.92 amperes, and an instantaneous power of 0.92 watts. Final power generation is a function of the number of times such loading and unloading can be performed per second.

  7 and 8 show an alternative embodiment of the energy harvesting device 200. The magnetic path 305 may be completely closed using a high magnetic permeability material, or may not be closed. The energy harvesting apparatus 200 of FIG. 7 includes the magnetic conducting bars 212 and 214 at both ends of the magnetostrictive rod having the magnetic material 205, and the second set of magnetic conducting bars 218 at both ends of the first set of magnetic conducting bars 212 and 214. , 310. The bias magnet 216 is not arranged in direct agreement with the magnetic path 305 but is arranged in a closed magnetic circuit loop formed by the magnetic material 205 and the magnetic conducting bars 212, 214, 218, 310. Even if the bias magnet 216 having this configuration is not necessarily located in the magnetic path 305, a part of the magnetic flux 305 can pass through the magnet 216, and the magnetic flux 305 generated by the magnetic material 205 can be changed.

  The energy harvesting apparatus 200 of FIG. 8 includes the magnetic conducting bars 212 and 214 at both ends of the magnetostrictive rod, but includes other magnetic conducting materials that connect the magnetic conducting bars 212 and 214 to form a closed loop of the magnetic conducting material. Absent. As a result, at least a part of the magnetic path 305 inevitably passes through the gap between the upper magnetic conducting bar 212 and the lower magnetic conducting bar 214 corresponding to each magnetic path loop. All of the configurations described herein provide power generation and demonstrate that some changes can be made to optimize power generation for a given design and application.

  FIG. 9 shows another embodiment of the energy harvesting device 200. In this embodiment, the bias magnet 216 or magnet is placed at the end of the magnetic material 205. In one embodiment, the magnet 216 is included in the load path when a prestress tension or compression load is applied to the magnetic material 205 by the load application device 210. As a result, the magnet 216 is in the load path and can therefore be subjected to either a compressive or tensile load 104 force. In another embodiment, a prestress force is applied to the magnetic material, after which the magnet 216 is placed. In such an embodiment, magnet 216 is maintained in a position unrelated to the load path and is not subjected to compressive or tensile load 104. In some embodiments, when the magnet 216 forms part of the load path, the energy harvesting device 200 is either pre-stressed or by an external load 104 applied to the load applicator 210 after applying pre-stress. It can be implemented by using high strength magnets or operating in a low load range so that it is not damaged or destroyed.

  Any of the embodiments of the load applicator 210 and / or magnetic material 205 described herein can be implemented in the energy harvesting device 200, and combinations of these embodiments can also be used. Other configurations of energy harvesting device 200, load applicator 210, and / or magnetic material 205 may also be used with any of the energy harvesting principles described herein.

  FIG. 10 shows a flowchart of an embodiment of a method 1000 for harvesting power from mechanical energy. Although the method 1000 is described in connection with the energy harvesting device 200 of FIG. 2, embodiments of the method 1000 can be implemented with other types of energy harvesting devices.

  The energy harvesting device 200 changes the magnetic characteristics of the magnetic material 205 using the load application device 210 (1005). The magnetic properties can be a function of the amount of stress applied to the magnetic material 205. One such magnetic characteristic can include the magnetic permeability of the magnetic material 205 such that the magnetic permeability changes when a stress is applied to the magnetic material 205. In another embodiment, the magnetic property is the saturation magnetization of the magnetic material 205. Increasing the saturation magnetization of the magnetic material 205 increases the effectiveness of the energy harvesting device 200 in some embodiments. Other properties that can change relative to stress include, but are not limited to, magnetization differentiation and magnetostriction with respect to applied stress.

  Next, at least one magnet 216 is placed close to the magnetic material 205 (1010). In order to apply a bias magnetic field to the magnetic material 205 and the energy harvesting device 200, the direction of the magnetic path 305 of the magnetic material 205 is changed by the magnet 216 (1015). In one embodiment, the magnet 216 contacts the magnetic material 205 at one end of the magnetic material 205. In another embodiment, the magnet 216 is not in contact with the magnetic material 205 and is close enough to change the magnetic flux 305 to a particular bias field. The magnet 216 can be placed in contact with the first magnetic conducting material located at the first end of the magnetic material 205. In some embodiments, the cross-sectional area of the at least one magnetically conductive material is approximately the same as the cross-sectional area of the at least one permanent magnet.

  The magnetic conducting material can be a bar 212 having a bore through which the magnetic material 205 passes, and the magnetic material 205 can be added to the bore. In some embodiments, the magnet 216 is located at the end of the magnetic bar 212 such that the magnet 216 is located in the magnetic path 305 generated by the magnetic material 205. In order to make the device generally symmetrical, the second magnetic bar 214 can be positioned at the second end of the magnetic material 205 and the magnet 216 can be positioned at the end of the second magnetic bar 214. . In other embodiments, the magnets 216 can be located at both ends of the magnetic material 205. The magnet 216 can also be positioned in the load path of the load application device 210.

  In some embodiments, the device 200 is a bar to produce a substantially closed magnetic path 305 with little air gap from the N pole of the magnetic material 205 through the magnetic conducting material to the S pole of the magnetic material 205. Additional magnetically conductive materials such as 218 can be included. In other embodiments, the energy harvesting device 200 can have one or more gaps in the magnetic path 305.

  In some embodiments, instead of being positioned directly in the magnetic path 305, the magnet 216 does not pass most of the magnetic flux 305 but still alters the magnetic flux 305 to provide a bias magnetic field to the magnetic material 205. The magnetic path 305 can be positioned within the loop. The number of magnets 216 and the magnetic force can be determined depending on the particular implementation of the energy harvesting device 200. Embodiments of the energy harvesting device 200 can implement the method 1000 with a magnetostrictive material, piezomagnetic material, or other type of magnetic material 205.

  In one embodiment, the conductive coil is positioned relative to the path of the magnetic flux 305 to induce a voltage in the conductive coil when the magnetic flux through the magnetic material 205 is varied by an external load 104 applied to the device 200 ( 1020). The amount of voltage is related to the type and number of turns of the coil and the time variation of the magnetic flux passing through the conductive coil. Other voltage induction methods can be implemented for the energy harvesting device 200 described herein.

  Prestress can be applied to the magnetic material in the energy harvesting device 200 in accordance with the principles described herein. Prestress may include a compressive or tensile load 104 applied to magnetic material 205 prior to placing magnet 216 in energy harvesting device 200 to bias the magnetic field of magnetic material 205, depending on the embodiment.

  In some embodiments, the magnetomotive force of the magnet in the magnetic path generates a magnetic flux in the portion of the magnetic path that includes the magnetic material and the first magnetic conducting material.

  In the above description, specific details of various embodiments are given. However, some embodiments may be practiced without all of these specific details. In other instances, certain methods, procedures, components, structures and / or functions have not been described in detail beyond merely allowing implementation of various embodiments of the present invention for the sake of simplicity and clarity.

  Although the operations of the methods are shown and described in a particular order, the order of operations of each method is such that a given operation is performed in the reverse order, or that a given operation is at least partly related to other operations. Can be modified to be performed simultaneously. In another embodiment, separate operation instructions or partial operations may be performed intermittently and / or alternately.

  While particular embodiments of the present invention have been illustrated and illustrated, the present invention is not limited to the specific cell or part arrangements described and illustrated. It is intended that the scope of the invention be specified by the appended claims and their equivalents.

Claims (19)

A device that harvests electrical energy from mechanical energy,
The device comprises a magnetic path,
The magnetic path is
A magnetic material having magnetic properties that are a function of the stress applied to itself;
A first magnetic conducting material proximate to the magnetic material;
A magnet that is located in the magnetic path and generates magnetic flux by its magnetomotive force;
Formed by
The apparatus further comprises a component configured to transmit a load change caused by an external source along the load path to the magnetic material, the magnet being independently located in the load path; Unaffected by the change in the load by the external source;
A device characterized by that. And further comprising at least one other component used to prestress the magnetic material, wherein the prestress on the magnetic material is compressed from the change in the load caused by the external source. The apparatus of claim 1, wherein the apparatus is stress .   The apparatus of claim 1, wherein the magnetically conductive material provides a magnetic path substantially free of air gap between the north and south poles of the magnet.   The apparatus of claim 1, wherein the first magnetically conductive material comprises mild steel.   The apparatus of claim 1, wherein the first magnetically conductive material comprises electric furnace steel. The magnet includes a permanent magnet positioned so that the component and the first pole of the magnet are in contact with each other , the first pole of the magnet facing toward the axis of the magnetic material, The apparatus of claim 1 , wherein two poles face outward of the axis of the magnetic material .   The apparatus of claim 1, wherein the magnet comprises an electromagnet.   The apparatus of claim 1, wherein the magnetic material comprises a magnetostrictive material.   The apparatus of claim 1, wherein the magnetic material comprises a piezomagnetic material.   The apparatus of claim 1, wherein the magnetic property comprises a permeability of the magnetic material that varies with mechanical stress applied to the magnetic material.   The apparatus of claim 1, wherein the magnetic property comprises a saturation magnetization of the magnetic material that varies with mechanical stress applied to the magnetic material.   The conductive coil further disposed relative to the magnetic path, wherein the conductive coil is configured to generate an induced voltage and / or current in response to a change in magnetic flux through the magnetic material. The apparatus according to 1. A device that harvests electrical energy from mechanical energy,
The device comprises a substantially closed magnetic path,
The magnetic path is
A magnetic material having magnetic properties that change with stress;
A magnetic material,
A permanent magnet located in the magnetic path;
The permanent magnet is oriented such that at least one pole of the permanent magnet faces the magnetic material;
The apparatus further comprises:
A component configured to transmit a load change caused by an external source to the magnetic material along a load path ;
At least one other component used to prestress the magnetic material, wherein the permanent magnet is located independently in the load path and the change in the load by the external source Unaffected by
A device characterized by that.   The apparatus of claim 13, wherein the magnetic material comprises a magnetostrictive material or a piezomagnetic material.   The apparatus of claim 13, wherein the magnetic property comprises a magnetic material permeability that varies with mechanical stress applied to the magnetic material.   The apparatus of claim 13, wherein the magnetic property comprises a saturation magnetization of the magnetic material that varies with mechanical stress applied to the magnetic material.   14. The apparatus of claim 13, wherein the cross-sectional area of the at least one magnetically conductive material is substantially equal to the cross-sectional area of the at least one permanent magnet.   The conductive coil further disposed relative to the magnetic path, wherein the conductive coil is configured to generate an induced voltage and / or current in response to a change in magnetic flux through the magnetic material. 13. The apparatus according to 13. A method of harvesting electrical energy from mechanical energy,
Changing a magnetic property of the magnetic material that is a function of stress applied to the magnetic material by a component configured to transmit a change in load by an external source along the load path to the magnetic material;
Changing the magnetic flux by a magnetomotive force provided by at least one permanent magnet located in a substantially closed magnetic path free of air gaps;
Wherein the step of in response to a change in the magnetic flux in the magnetic material induces a voltage in a relatively arranged conductive coil and the magnetic path, only including,
The permanent magnet is independently located in the load path and is not affected by the change in the load by the external source;
A method characterized by that .

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