Alignment independent and self-aligning inductive power transfer system using mobile, flexible inductors

Abstract

An inductive power transfer device is provided for recharging cordless appliances. The device includes a plurality of inductors arranged in an array and connected with a power supply via switches which are selectively operable to activate the respective inductors. The inductors serve as the primary coil of a transformer. The secondary coil of the transformer is arranged in the appliance. When the appliance is arranged proximate to the power transfer device with the respective coils in alignment, power is inductively transferred from the device to the appliance via the transformer.

Description

REFERENCE TO PRIORITY DOCUMENTS

[0001] This application claims priority to under 35 USC §120 and is a continuation of U.S. patent application Ser. No. 10/960,102, filed Oct. 8, 2004, said application Ser. No. 10/960,102 claims priority under 35 USC §120, is a continuation-in-part, claiming priority under 35 USC §120 to U.S. application Ser. No. 09/702,234, filed in the USPTO on Oct. 31, 2001, and issued as U.S. Pat. No. 6,803,744, issued Oct. 12, 2004, which is incorporated by reference for all purposes. U.S. patent application Ser. No. 09/702,234 claims priority under 35 USC §119(e) to U.S. Provisional Application Ser. No. 60/162,295 filed Nov. 1, 1999, which is incorporated by reference for all purposes.

BACKGROUND OF THE INVENTION

[0002] The present invention generally relates to inductive power transfer devices for charging or powering cordless appliances.

[0003] Currently, cordless electrically operated devices are charged by a source of electrical energy only when the device and source are connected to one another. Normally, the source includes some sort of pedestal to which the device is connected before charging may occur. The drawbacks of such an arrangement are self-evident. For example, when working with a cordless drill, it is often necessary to mount a battery which must be removed from the drill, or the drill itself, on the charger before the charging process can begin. If the charger is not kept in close proximity, the drill battery must be moved to the charger. The present invention differs significantly from the known prior art wherein the source and devices are specifically matched to only operate when the receiver is mounted on the holder for recharging. The present invention provides a novel system for automatically charging a device whenever it is placed on a rest surface without a direct electrical connection, regardless of the orientation of the device on the surface.

SUMMARY OF THE INVENTION

[0004] Accordingly, it is a primary object of the invention to provide an induction power transfer device for an appliance including a housing and a plurality of primary inductors or coils arranged in an array within the housing. A circuit connects the inductors with a power supply and a plurality of switches connect each inductor with the circuit. The switches are operable to selectively activate respective primary inductors so that when an appliance having at least one secondary inductor is placed on the housing, power is transferred to the appliance via a transformer defined by the primary inductors and the secondary inductor.

[0005] According to a further embodiment of the invention, at least one of the primary inductors has a longitudinal axis arranged normal to the axes of the other primary inductors.

[0006] The housing preferably has a flat top wall beneath which the primary inductors are arranged in a plane parallel to the wall. An appliance placed on the wall has its secondary inductor inductively coupled with at least one of the primary inductors.

[0007] According to a further object of the invention either the inductive transformer device or the appliance may include an alignment mechanism to assist in aligning their respective inductors to maximize power transfer.

[0008] According to another object of the invention, capacitors are provided for each primary inductor to balance the inductance thereof.

[0009] In accordance with the invention, a user could merely place the appliance such as a cordless power tool, laptop computer, or recording device on a table, shelf or other common storage member and the charging process occurs automatically, regardless of the orientation of the receiver relative to the charging source. This would result in the appliance being charged whenever it is not in use, rather then merely resting on a work table between uses as in current practice.

[0010] The unique assembly of the present invention assures that the transfer of inductive power will occur regardless of the orientation of the appliance relative to the charging source. To achieve this result, the source may be configured with a number of coils that are arranged in predetermined positions that optimize the transfer of power to the appliance for certain applications such as a maximum duty cycle, i.e., power transfer density, or minimum obtrusiveness.

BRIEF DESCRIPTION OF THE FIGURES

[0011] Other objects and advantages of the invention will become apparent from a study of the following specification, when viewed in the light of the accompanying drawing, in which:

[0012] FIG. 1 is a front plan view of an induction power transfer device in the form of a table in accordance with the invention;

[0013] FIGS. 2-5 are circuit diagrams, respectively, showing various ways in which a plurality of inductors is connected in the induction power transfer device according to the invention;

[0014] FIG. 6 is a circuit diagram of the induction power transfer device including capacitors for inductors;

[0015] FIG. 7 is a diagram showing the arrangement of inductors of the power transfer device and of an appliance to form a transformer;

[0016] FIGS. 8 and 9 are front and side views, respectively, of an embodiment of the invention being activated by an appliance;

[0017] FIG. 10 is a diagram of a further embodiment of the invention including annular contacts thereof;

[0018] FIGS. 11 and 12 are sectional views showing movable inductors in an appliance for alignment with an inductor of the induction power transfer device;

[0019] FIG. 13 is a diagram showing an alignment mechanism of the invention; and

[0020] FIG. 14 is a diagram illustrating a further embodiment of the invention for simultaneously charging a plurality of appliances.

[0021] FIG. 15a is a top view of dispersed self-forming flexible inductor (along a z-axis);

[0022] FIG. 15b is self-forming beginning to coalesce;

[0023] FIG. 15c is self-forming inductor fully coalesced.

[0024] FIG. 15d is self-forming (x-y axis) inductor in a relaxed, dispersed condition;

[0025] FIG. 15e is a self-forming inductor (x-y axis) beginning to coalesce;

[0026] FIG. 15f is self-forming inductor fully coalesced (x-y axis);

[0027] FIG. 16 is a cross-section of a self-forming inductor in a top view;

[0028] FIG. 17 illustrates a dispersed coils shape memory material is relaxed state

[0029] FIG. 18 illustrates a tightened state of the inductor;

[0030] FIG. 19a illustrates mobile inductor within a housing within a non-aligned load;

[0031] FIG. 19b shows mobile inductor having moved to align with the load;

[0032] FIG. 19c illustrates shows a variant with wheels that can swivel;

[0033] FIG. 20a illustrates shows an additional variant of a mobile inductor from a top view;

[0034] FIG. 20b illustrates shows an side view of the additional variant inductor within a housing;

[0035] FIG. 21a illustrates a grid of selectively energize-able circuit elements;

[0036] FIG. 21b illustrates circuit elements selectively energized;

[0037] FIG. 22a shows an array of rotatable conductor elements;

[0038] FIG. 22b shows certain elements rotated as to constitute an inductor.

DETAILED DESCRIPTION

[0039] The invention relates to an induction power transfer device which is operable to charge a cordless battery powered appliance such as a hand tool, laptop computer, music player, or the like. In its broadest sense, the invention is a universal inductive interface power connection system including both a powered "source" and a cordless "receiver" which can be used together to transfer power from the source to a variety of receivers for charging the same.

[0040] The induction power transfer device includes a housing which may take one of several forms. In FIG. 1, the housing comprises a bench or table 2 having a flat upper surface 4. Beneath the surface is a planar array of inductors 6 which operate as the primary inductors of one or more transformers. As will be developed below, each inductor comprises a coil having a longitudinal axis. A magnetic core may be provided for each coil.

[0041] The inductors 6 are connected with an electrical conductor 8 which in turn is connected with a power supply 10. In addition, an electrical switch 12 is connected between each inductor 6 and the conductor 8 so that the primary inductors can be selectively activated. For example, in FIG. 1, four inductors 6 are shown, but only the first and fourth have their switches closed to supply power thereto for activation.

[0042] Resting on the top surface 4 of the table 2 are two appliances, namely, a laptop computer 14 having a secondary inductor 16 and a cordless drill 18 having a secondary inductor 20. When the secondary inductors 16, 12 are aligned with primary inductors of the power transfer table 2, power is transferred from the table to the appliances, i.e., the laptop computer 14 and the drill 18 via transformers defined by the adjacent primary and secondary inductors. This power can be transferred to a battery in the appliance to charge the battery in order to power the appliance. Thus, for example, as represented by the block 22 in the drill 18 of FIG. 1, power from the secondary inductor 20 is supplied to a battery. A switch then activates the motor of the drill for operation.

[0043] It will be appreciated by those of ordinary skill in the art that the housing may take many shapes. For example, it can be formed as an elongated strip or pad on which an appliance may be rested, or a tool belt against which a power tool can be suspended. With the invention, any time an appliance is not in use, it can be rested or placed on the power transfer housing and recharged owing to the proximity of the primary and secondary inductors.

[0044] Referring now to FIGS. 2-5, the inductors 6 can be arranged in various patterns to insure charging of an appliance regardless of the position of the appliance on the housing on the power transfer device. In FIG. 2, a plurality of inductors 6 are connected in series with a source 10. In FIG. 3, some inductors 6a are arranged with their longitudinal axes normal to the axes of the inductors 6, with all of the inductors arranged in the same plane. FIGS. 4 and 5 show additional arrays of inductors in series and square configurations, respectively.

[0045] While the drawings illustrate a fixed number of inductors, it will be appreciated that the invention is not so limited and that any number of inductors may be provided to define an array as large as the housing in which it is arranged.

[0046] Preferably, the power transfer device inductors are arranged as close as possible to the inside surface of a protective wall of the housing (FIG. 1) which should be thin enough not to unduly separate the source and receiver inductors and thereby diminish the ability to transfer power to the receiver resting on the cover. Advantageously, the multiplicity of source inductors is connected in parallel to pairs of supply lines, which pairs of liens extend to the power supply via interposed coil switches to allow only those coils in proximity to the receiver to be selectively energized.

[0047] In an alternative arrangement shown in FIG. 6, the source coil is energized through a single supply line provided one coil lead is connected to the line and the other lead coil is connected to a capacitor 24. To maximize power transfer, sufficient capacitance may be needed in series with each inductor to keep the current in phase with the voltage. Accordingly, capacitors are arranged relative to the interface when the appliance and the source are in mating positions so as to provide capacitive coupling for additional power transfer. Such transfer may be weak relative to the inductive transfer generated between the primary coils mounted in the source and the secondary coils mounted in the appliance.

[0048] As stated above, the source inductors may be oriented parallel or normal to the array plane. The inductor coils may include a compressed portion extending substantially parallel to the mating surface (similar to the flat portion of the letter "D" as shown in FIG. 7) to increase magnetic permeation from the source to the appliance. Alternatively, the coil cross-section may be customized to follow the contours of the mating surface to maximize permeation. The coils may take the form of an air coil or may have iron and/or other material extending through the core to improve transmission of the field lines between the source and the appliance.

[0049] The core of the inductors may be formed of magnetically permeable fibers, threads or tubes in air or oil or a binding matrix which could consist of a viscous fluid or elastomer either of which could be designed to soften as the air temperature around the coil rises. This would result in the magnetic core fibers migrating into the most efficient configuration for transmitting power through the interface with the appliance, while avoiding the potential inconvenience of a fluid filled array. It will be readily appreciated that, by choosing a matrix configuration which has some compressive strength when not heated by the presence of an operating interface, the coils within the cord or other array may be protected against crushing when subjected to transverse forces. Alternatively, the core matrix could be fluidized by the presence of the electrical or magnetic activity at the interface between the source and the appliance, such as by a magnetic core fiber being non-aligned with the field lines of the interface, which tends to generate more heat than an aligned core. The fluid core arrangement allows the cores to configure themselves into the most efficient configurations with respect to any established interface configuration, by curving toward the mating surface end of the coils.

[0050] The inductors mounted in the appliance should be embedded near the surface of the device that comes in proximity with the source pad or table as shown in FIG. 1. For example, the inductor coil(s) may be embedded near the bottom surface of a laptop computer for inductively coupling with any source array mounted in a seatback tray on an airplane, train computer table, etc. This would allow the laptop to be recharged while resting or in use. In a similar manner, a power tool may include a coil array positioned adjacent to a surface of the tool that would conveniently rest on the source pad, thereby allowing the tool to recharge while laid to rest.

[0051] To assure that the appliance will recharge no matter its orientation relative to the source array, it is preferable that the appliance include a set or plurality of inductors, i.e., solenoid coils with some arranged parallel and some arranged normal to the surface of the source pad. When the coils are arranged parallel to the surface, they have a dispersion of x-y orientations such as a tessellated polygonal or square grid, so that at least some of the appliance and source coils are in alignment with each other to allow efficient inductive coupling between the source and the appliance.

[0052] In FIG. 7 is shown a further embodiment of an inductive power transfer device 102 for an appliance 104. The device 102 includes separate coils 106, 108, with the coil 106 having a magnetic core 110 contoured to the core 112 of a secondary coil 114 of the appliance. Each primary coil 106, 108 also includes its own power source 116, 118 in lieu of a switch for activating the coil.

[0053] Rectification can be provided to each lead from each coil in the form of a pair of diodes 120 of opposite polarity on each coil lead with the output of each diode feeding the appropriate side of the battery. In this embodiment, each increment of power generated in any secondary coil in each inductive cycle caused by the power supply will be captured. For ease of manufacturing, all output leads from the diodes of one polarity could go "up," i.e., in the +z direction relative to the x-y plane of the array to contact an essentially planar bus such as used in a PC board comprising the inner side of an appliance array. The other polarity diode output leads could go "down," i.e., -z to a similar bus positioned on the outer side of the receiver cavity.

[0054] It is desirable for the source coils to only operate when an appliance is laid to rest on an item containing the source coils. By preventing the source coils from continuously generating an electromagnetic field, the system would conserve power while eliminating objectionable electromagnetic fields. This result is achieved by the switches 12 (FIGS. 2-5) provided so that each source or primary coil is energized from the power supply only when a secondary coil is within effective range and there is sufficient translational and rotational alignment between primary and secondary coils.

[0055] Referring to FIG. 7, this arrangement can be achieved by residual permanent magnetism in the appliance 104 or by a separate magnet 112 associated with each secondary coil 114 which operates a magnetic switch, a MOSFET, or similar switch (not shown) to turn the source coil on or off. Alternatively, the coils could be selectively energized by a resonance created between the primary and secondary coils which resonance amplifies a tiny residual power flow in each source coil. A further means for controlling energization may include a piezoelectric, or other oscillator in a tuned circuit pumped by random vibrations which generates feedback amplification when in proximity to a matched oscillator, thus opening a power transistor and/or OP-AMP between the coil and supply line once a threshold is reached. The coil switch (including transistor and/or OP-AMP) could also be operated by any kind of tag such as a microchip associated with each receiver coil which could generate its own signal (acoustic, radio, etc.) or respond to a polling signal from a matched device associated with each source coil.

[0056] In the alternative embodiment of FIGS. 8 and 9, a continuous source coil 202 with multiple leads or taps 204, i.e., at regular intervals going to the supply line, up to the limit of one lead (or tap) per coil going to each side of the power supply 208 can be provided. A coil switch is on every lead so that whatever length of source coil is in range of the receiver coil is activated. A continuous integrated circuit coil switch ("CICCS") may take the form of a ribbon or strip of a magnetoreactive semiconductor, possibly organo-polymeric in nature, which goes into its conductive mode when in the presence of a magnetic field emanating from a secondary coil 210 in close proximity. In one embodiment, a magnetic north responsive CICCS is deployed to be in continuous contact with one supply conductor and each coil tap connected to the N-CICCS so that power from the supply conductor must traverse the width of the N-CICCS to reach the tap. A south (magnetic) responsive CICCS is similarly deployed between the coil taps and the other source conductor. When a secondary coil with a permanent magnet 212 as its core is positioned at a position wherein the magnetic fields interact, the N end of the core magnet opens the N-CICCS and the S end of the core magnet opens the S-CICCS, wherein the points of opening of the N-CICCS and the S-CICCS are separated by exactly the length of the receiver inductor whose core magnet opened the two CICCs, forming a circuit from one supply line to the other supply line that extends through the corresponding segment of the source inductor coil or a single CICCS could be used in the single lead with a capacitor scheme. Alternatively, the CICCS could be opened by other conventional devices.

[0057] The power supply 208 for generating the electromagnetic field in the source inductor coils may be either AC or intermittent DC, such as half-wave rectified. The power supply may vary at line frequency (60 or 50 Hz.) or a power supply with a higher frequency oscillator may be employed. The inductive power transfer is proportional to dv/dt, minus losses to self inductance, which increase with increase in frequency.

[0058] In another preferred embodiment of the present invention shown in FIG. 10, maximum transfer of power is achieved by allowing the coils forming either the primary 302 or the secondary 304 to move relative to the other set of coils. If one set of coils is allowed to move, i.e., to translate as much as one-half or more of the intercoil spacing in either the x or y direction or both and to rotate as much as one-half of the intercoil angle or more in either direction about the z axis so that via an engagement alignment device such as a core magnet the coils or arrays can achieve maximum alignment when forming a coupled transformer. To achieve this result, the movable coils or arrays may be set in a non-conductive container or lozenge 306 preferably having an annular configuration with connections provided either by flexible wires, or by brushes and concentric commutators on the lozenge body designed to exclusively contact the appropriate brush. Alternatively, the upper and lower surface of each inductive coil/array-lozenge may functionally serve as the output brushes for the secondary inductor coils or arrays, which brushes transmit any power generated to the upper and lower internal surfaces of the cavity in which the inductor coil/array lozenges are free to move transitionally and rotationally. These surfaces 308 serve as sliding contacts or commutators, collecting power from the secondary coils and sending it to the device's battery, switch and end user circuitry.

[0059] The secondary and/or source coils could also take the shape of flexible coils which are free to bend and migrate within a cavity formed in either the source or appliance device. Alternatively, the flexible coil may be free from the constraint of any cavity, so as to best align with its mating coil. Motion of the coils (within or without their cavities) is facilitated by a vibrator which is briefly energized when a coil-switch is opened, with the vibrations making it easier for the coils to migrate into alignment with each other and/or by an active seeker mechanism (FIGS. 11 and 12) attached to the coil. The vibrator could be periodically energized. It and the seeker are also usable with any other form of the inductor coils.

[0060] The seeker mechanism 402 is attached to any movable source or appliance inductor which mechanism is designed to bring the primary and secondary coils into ideal alignment for inductive coupling. In FIGS. 12 and 13, the appliance 404 has the movable coil 406. This may be achieved by means of a piezoelectric or piezomagnetic leg 408 extending from each side of the movable inductor 406 to contact the inner side of the mating surface which is designed to flex (under influence of the electric or magnetic flux at the interface) in a direction which will move the inductor into alignment with the primary coil 410 as shown in FIG. 12. The legs may be made of materials of opposite polarity in the dorsal and ventral region to cause lateral motion. Furthermore, end portions of the legs may need to have a biased grip to engage the mating surface. Alternatively, the lower leg portions may have a coefficient of friction which varies with the variations in electric or magnetic fields. As a result, the lower portions of the legs grip the mating surface more strongly during that phase of the motion which would bring the coil into alignment. This may apply to a mobile discrete inductor or a flexible inductor which could be arrayed in their space in an "s" curve to allow motion of the central portion or other arrangement.

[0061] An advantageous form of inductive interface system shown in FIG. 13 includes bumps or waffles formed in the exterior surface of the source pad 502, which bumps correspond to locations of a source coil or array. The bumps or waffles would mate with indentations in the cover of the appliance coil or array 504a-e so as to provide a simple system of aligning the mating coils resulting in high interface efficiency. The system of bumps and indentations might be positioned with one bump located at each end of each coil, or a pair of bumps on either side, or any other suitable arrangement. The source array is preferred for the bumps, as indentations would tend to accumulate sawdust or the like from the workplace which could impede inductive coupling efficiency. The ideal system of bumps and indentations is envisioned as having the cross section of the upper half of a sine wave, so that a receiver array will sit casually on a source array and will tend to rotate and translate under the influence of gravity and/or magnetic or other attraction into maximum alignment. By proper sizing and spacing of the bumps into a shape similar to the sinusoidal undulating wave form of array, a good degree of interoperability may be achieved.

[0062] For power tools and other uses requiring larger amounts of power, a grooved form of source and receiver array may be employed, wherein the surface is described by a sinusoid undulation (possibly flattened on tops to allow interface with flat surfaced interfaces) with the coils disposed in the convex portions of the sinusoid. This arrangement assures that when sinusoidal powered source and appliance arrays are located proximate to each other, inductive interaction of source and appliance coil arrays is maximized. Sinusoids could be transverse to each other, such as in a power tool power cord/strip so as to facilitate rolling up of cord/strip, or longitudinal (if such axes are identifiable).

[0063] Another form of inductive interface system formed in accordance with the present invention may consist of a source array disposed on the end of an extension cord which would engage with a secondary array disposed on a power tool or other device. This could provide power for 100% duty cycle even with the heaviest of usage, and yet be readily disconnected at any time, merely by manually applying tension, or via one of the disengagement devices discussed hereabove. Another form of the invention includes a small table/toolrest with source arrays in the surface, with the table having extendable legs that allow the table to be positioned where needed.

[0064] A major feature of the "Universal Inductive Interface Power Connection System" comprising the present invention resides in the fact that while configurations and densities of source and appliance arrays may be optimized for different applications, different sources and receivers are at all times interoperable. For example, a flat surfaced array may be employed with a sinusoid surfaced array and vice versa. As a general rule, the maximum current available for power transfer will be a function of interface area, inductor density and the coupling efficiency factor. With a standardized source coil density, the secondary array maximum voltage will be a function of appliance coil density, as in any transformer.

[0065] Referring to FIG. 14, all forms 602a-d of the source array which might be desirable on a job-site or in a home or office, would have both a plug 604 for receiving power from wall socket or other source 606 and a socket 608 or more so that other forms of course array may be connected together to provide a broad spectrum of recharging possibilities. For example, a long power cord array could stretch the entire expanse of a job-site, providing opportunities along its entire length for a modest rate of recharging, and forms of source arrays such as a pad comprising the upper surface of a shelf of a work table could be connected to and derive power from the conductors of this power cord. This would provide faster recharging than otherwise available. It would also provide efficient recharging at locations on the job-site of heaviest tool use. Source pads or other containers for the source inductor coils employed in the charging system of the present invention may advantageously be set upon tables, workbenches, saw horses, shelves or the like to relieve the worker of the current necessity of bending over each time it is desired to put down or pick up a tool from the ground, which is customary practice at most construction sites. A single source inductor array located on an extension cord may be connected at another location, with a sinusoidal undulating source array at another location and a bump array at another, to provide additional recharging opportunities. The different source arrays could also transfer power to each other through their inductive interfaces. Thus, there would be no further need for a conventional plug and socket connection to recharge the device.

[0066] It is preferable to provide for positive engagement between the receiver and the source. This may prove useful when the source is positioned other than in a horizontal position and when the interface is subjected to vibration or jostling, since it produces a tighter magneto-inductive coupling (between source and appliance) by ensuring the best proximity and/or alignment of coils. This, in turn, helps overcome possible magnetic repulsion between the coupled sets of source and appliance inductors. This desirable result may be achieved by provision of a magnet, e.g., a permanent magnet, in the center or edge of each repeating coil unit of the appliance or source coils to mate with another magnet or magneto attractive mass positioned in the center or edge of each repeating coil unit of source or appliance coil, respectively.

[0067] The iron or other core material employed in each inductor coil has a sufficient degree of permanent magnetism to function as engagement devices, since these cores are ideally located for this purpose. In effect, the magnetic attraction is sufficient to open the coil switch and thus operate the charging system. However, it could be that the degree of permanent magnetism needed to align the coils is incompatible with the electro-magnetizability (permeability) required for the core to function efficiently in an inductor, in which case the alignment magnet may be set orthogonal to the inductor primary axis of the "x-y" plane, preferably mutually centered, as shown in FIG. 8.

[0068] If each coil has a degree of mobility at each of its ends approximately equal to half the spacing between coils, intercoil spacing will allow the pairs of coils to assume alignment. Such mobility of the coils can be achieved by using braided wires in the coil connections and a housing larger than the diameter of the coils. This allows the coils to slide in the x-y plane, wherein one surface of the housing is the interface surface of the source array. Alternatively, Velcro® mating tongues and grooves in the source and receiver or mating physical structures may be employed as engagement members. In each of these embodiments, the fact that the housing is larger than the size of the coils makes it possible for the pairs of coils to achieve proper alignment. Alternatively, the housings for the source and appliance arrays could be magnetically attractive to each other.

[0069] Once the source and appliance coils are brought in proximity with each other, a disengagement device may be required to break the electromagnetic bond. Disengagement may be effected by physically moving the appliance away from the source, reducing the magnetic coupling. Alternatively, if a magnet functions as an engagement device, it could be mounted in an opening in the appliance such that the magnet could be moved within the appliance away from the source, in the z direction away from the interface, thereby reducing the magnetic force of engagement. This movement could be achieved mechanically by the squeezing of a trigger in the appliance, or electrically through a trigger switch. Alternatively, a contact detector responding to a user's touch could be employed. The detector actuates a solenoid connected to the engager, pulling away from the interface. Disengagement is achieved by sending a back voltage through any activated secondary coils, so as to generate a repulsive magnetic force against the primary coils. Alternatively, a forward voltage could be sent through the activated receiver coils if the inductive coupling generates a net repulsive force which in operative engagement must be countered by the attachment system, thereby increasing the repulsive force in the inductive coupling and overcoming the attachment force.

[0070] So as not to waste power in systems where primary coil to secondary coil alignment is not assured, either the theoretical maximum voltage output of the appliance array should be higher than the desired output by a factor inverse to the cosine of the greatest operational misalignment of a coil-set and any excess voltages diverted and added with other excess voltages from other coil sets and input to the appliance, or the secondary coils can be multitapped, with the tap producing optimal voltage automatically selected by a trimmer circuit. Alternatively, the maximum theoretical output voltage can be set equal to a desired input voltage, and voltage multiplier circuits used to increase any low voltages resulting from any misalignment. Exact voltages are achieved by using conventional means, i.e., variable resistors, to split the original voltage, only multiplying a portion of it, which is added back or by any conventional arithmetic circuit.

[0071] It may be desirable to include a battery/fuel cell overcharge prevention circuit, which would operate to disable the system either by electrically isolating the engaged secondary coils or, preferably, by turning off the coil switches of any source coil actuated due to secondary coil proximity. Alternatively, the secondary coils could be physically relocated within the body of the appliance, to reduce magneto-inductive interaction.

[0072] A rechargeable fuel cell system may be employed with the inductive interface as the recharging device, wherein the secondary array in the powered device will, after receiving power from a source array, cause the fuel within the fuel cell to be regenerated from the oxidation products of the fuel cell's operating reactions. For example, in a hydrogen fueled system, the hydrogen fuel for the fuel cell would be stored in the form of a metal hydride, a saturated graphite or fullerance (possibly doped with electrophiles such as lithium and/or electrophos), or compressed gas, which in the absence of power from an inductive coupling of the secondary array, would react with atmospheric oxygen to produce electricity and water. The water would be stored and the electricity used to power the device. When later connected to a source power array and receiving power through inductive coupling, the stored water would be reduced by hydrolysis using electric power from the inductive coupling into hydrogen which would be stored in the above cited storage device, and oxygen which would be released to the atmosphere. If the system lost its hydrogen, it could be replaced as water, and hydrolysis would occur as stated above through the inductive power transfer, to put the fuel cell system back into a charged condition.

[0073] In a preferred embodiment of the present invention, a power tool having one or more inductive secondary coils formed in accordance with the present invention may be laid to rest on either side on a source pad having an array of built in primary coils. Secondary coils are positioned in the bottom and/or along the sides of the tool, or may be located in the bottom of a battery pack which itself may be detached and replaced. Whether the secondary coils are mounted in the power tool or in an attachment to the tool, by positioning the power tool with its interface (inductor secondary array) on a source pad or similar receptacle including the source inductor array, it becomes possible to charge the power tool between operations, merely by placing the tool on the source pad, thus maintaining a sufficient charge in the power tool at all times. The extra batteries or fuel cells could be recharged on the same source array.

[0074] For extremely severe use, the source array could be set on an incline so that exhausted batteries would be set at the top of a sequence of batteries on the incline, and the battery which has charged for the longest period of time could be withdrawn from the bottom of the incline.

[0075] A job-site source array might take the form of a coilable flat power cord ribbon about 1/2-inch thick by 2-6 inches wide by any length from 2-100 feet. Workers conveniently lay their tools on the ribbon when not in use. The edges could be tapered to prevent tripping. One end ribbon may have a cord adaptable to being plugged into a conventional electric outlet. It could also have sockets into which may be plugged other appliances and source arrays. The flat power cord ribbon could have a central stripe of ferrous material with a separate strip of source coils complete with coil switches and supply conductors on either side. The ribbon would be designed to mate with a receiver array consisting of polygonal cells of diameter equal to the spacing of the two strips of source coils, composed of secondary coils with supporting circuitry and with a magnetic button at the center of each polygonal secondary array, thereby assuring good coil alignment.

[0076] In all instances in which an inductor has been described as being in the x-y plane, i.e., its longitudinal axis parallel to the plane of the interface, an inductor being in the z direction, i.e., its axis normal to the plane of the interface, may also be provided, and an inductive array may contain both parallel and normal inductors.

[0077] A signal can be transmitted through the same inductive array which transmits power from a source to an appliance by injecting the signal into the interface at an appropriate frequency through an appropriate filter and removing it on the other side of the interface through another appropriate filter. In this way, computers and all types of portable and non-portable devices can communicate when they are engaged through an inductive interface.

[0078] While the preferred forms and embodiments of the invention have been illustrated and described, it will be apparent to those of ordinary skill in the art that various changes and modifications may be made without deviating from the inventive concepts set forth above.

[0079] A wire which upon sensing the presence of an inductor which seeks to establish an inductive mating (interface) with it, will coil itself so as to form an inductor.

[0080] This wire may be initially disposed as a loose coil or array of coils within a broad flat cavity defined on the mating surface side by a thin wall, as in FIG. 15a. These coils would increase their curvature (i.e. tighten their radius) when in the proximity of the mating inductor, so as to increase the number of coils there (thus increasing the amount of inductor there) at the expense of the number of coils elsewhere. In effect, the coils, which were built into the wire, would migrate to the interface location and achieve the correct alignment, as in FIG. 15b, until maximal concentration of the coils at the inductor mating location is achieved, as in FIG. 15c.

[0081] In the embodiment as described above, the wire-coils are dispersed flatly in the housing cavity for a z-axis coupling (i.e. solenoid axis orthogonal to the mating surface) FIG. 15a-c.

[0082] In an alternative and equally valid embodiment, these coils would have their solenoid axis in the x-y plane, i.e. parallel to the mating surface. In this case, there would be relatively many coils of a smaller diameter, as is known from conventional inductor design. As in the previous example, the coils would be somewhat loosely dispersed in the cavity (FIG. 15d), until a mating inductor made it's presence felt, at which point the coils would begin to coalesce adjacent to it as in FIG. 15e and finally constitute a fully formed inductor as in FIG. 15f.

[0083] It should be understood that it may be a physical property of the wire of these coils which causes them to tighten their radius and coalesce into an inductor, or it may be a property of the insulation or of an element parallel to the wire, such as a piece of nitinol or other shape-memory or shape-changing material, or it may be a specifically responsive servo-mechanism with micro actuators dispersed along the length of the wire.

[0084] Specifically examining the example of a nitinol or other shape-memory wire embedded with (301) or identical with the inductor wire (302), in the same insulation sheath (303), as in FIG. 16. The hot condition of the nitinol (etc.) would be the tighter radius of curvature as in FIG. 18, versus the cold condition or shape which would be the looser radius of curvature as in FIG. 17. In one embodiment said hot condition would be invoked by the waste heat from the (initially small) induction in the region where the mating inductor has been placed, which said heat and said inductive coupling will progressively reinforce each other until all or most of the formerly loosely arrayed coils are tightly clustered into an inductor, adjacent to and coupled with the mated inductor which caused it to coalesce, into an inductor, as in 15a-c and 15d-f.

[0085] In an x-y axis coil-inductor, since there are many coils diameter it may be desirable to have the nitinol or other shape-changing element as described above, not run parallel to the conductor, but form a mandrel about which the wire coils. This mandrel could be a coil of the same diameter(s) as the conductor coil, but with a fraction of the helical pitch (i.e. # of coils length), and affixed to the insulation at each point of crossing, or even to the wire itself, if the shape-changing coil is a sufficiently weak conductor as to not divert current from the conductor-inductor wire (which could heat and deform the entire length of the shape-changing element). (Alternatively, it may be that by balancing the conductivity of the nitinol etc, with the main wire, a small portion of the total current would go through the nitinol etc. and heat it causing it to curl as desired, if there were coil switches dispersed along the whole coil length, so that only the region in proximity to the mating inductor were energized.) The reason for having less turns of the shape changing element is that then for a given mass it could be thicker and thus exert more force. Of course, the shape changing component could be a solid or tubular core for the inductor coils, which shortens in proximity to the mating inductor, due to heat, or the presence of electric or magnetic fields, thus causing the coil to concentrate in this region. It could be plastic. It could be the insulation itself

[0086] The mating inductor could send out a signal which turns on the coil coalescence system, and this signal could also activate the coil switch(s) which allows electricity to pass through the coil. It should be understood that these above forms of inductor could operate free of a housing.

[0087] In another preferred embodiment, when it is desired for discrete inductors to be mobile within their apparatus so as to achieve alignment with a mated inductor, as described in the parent application Ser. No. 09/702,234 (which is incorporated by reference, and beginning pg 10 In. 17 through pg. 12), the mobility and alignment of said inductors may be achieved by equipping each mobile inductor with a sensor means to detect proximity and direction of/the mating inductor, connected to a motion causing means which moves the inductor in the direction indicated by the sensor. This motion causing means could be small motorized wheels associated with the inductor, which wheels bear upon the inside surface of the broad flat cavity parallel to the mating surface in the apparatus in which the inductor is to move about. These wheels (or wheel) would move the inductor into mating alignment.

[0088] For x-y inductors, both translational and rotational alignment would be required to be made by this alignment mechanism, the 3 degrees of freedom (x,y, and rotational) requiring at least 3 mechanisms. For a z-axis inductor, since it has rotational symmetry in the x-y plane, only two degrees of freedom exist and only two directions of motion are required. This could be done by an x-axis mechanism (such as a motorized wheel or jack screw or other mechanism) and a y-axis motorized wheel or jack screw or other mechanism, or it could be achieved by a single wheel which pivots, with one motor or means to pivot the wheel for movement in any direction such as is determined by the sensor to be toward the mating location, and another motor or means to roll the wheel towards that point. In a possible preferred embodiment, that single wheel could be centrally located in the core region of the inductor it could be a spherical wheel. The overall appearance would be similar to a computer mouse. FIG. 20a shows a top view of such a mobile inductor, and FIG. 20b shows the side view of same. 601 is the inductor coils, 602 is the wheel, 603 is the rolling motor, 604 is the pivoting motor, 605 is the sensor, 606 is the housing cavity, and 607 is the pivot axis.

[0089] FIG. 19a shows a side view of an x-y axis mobile inductor sensing a mating inductor and moving into (translational) alignment. FIG. 19b show alignment achieved. In these FIGS. 501 is the sensor, 502 is the mating inductor, 503 is the device powered by the inductor's interface, 504 is the inductor housing with a broad flat cavity for the mobile inductor, 505 is the mobile inductor, 506 is the motor connected to the wheel 507 which moves the inductor, And 508 is the connection by which the sensor controls the motor(s). FIG. 19c is a top view of the same x-y inductor showing the wheels pivoted by another mechanism so that the inductor may achieve rotational alignment with its mating inductor.

[0090] In another important embodiment of the invention; the inductor array is composed of a 2-dimensional (x-y) tessellated grid of inductor elements (as described in the parent application Ser. No. 09/1702,234), in which each element of the grid is a conductor or small inductor element which when a plurality of these are electrically energized in the correct pattern such as in direct response to the presence of a mating inductor, will constitute an inductor of sufficient power and such orientation as to inductively transfer power to the mated inductor. Each grid element would in response to the field information from the mating inductor, orient its axis of conduction or induction in the correct direction so that the required inductor was created. Within each grid element this could occur by selective activation only of those conductive or inductive elements of a multiplicity of such elements 701 running in different directions as in FIG. 21a, which are running in the required direction 703, due to the influence of mating inductor 702 (which is shown elevated above it for ease of illustration) as in FIG. 21b, or it could be achieved by rotation of the grid element which only contains one direction of conductor or inductor, into the correct orientation, as in FIG. 22a-b with FIG. 22a showing the disorganized state wherein 801 are the randomized grid elements and FIG. 22b showing the inductor organized under the influence of the mating inductor 802 (again shown displaced for ease of illustration) and 803 being the directional organized grid elements.

[0091] Each grid element could have its own power connections, so that the system would be independent of establishing perfect connection between all of the grid elements required to be connected to constitute a working inductor.

Claims

1. A power transfer system, including power connection means, said system with at least one inductor in which said at least one inductor is mobile such as to achieve alignment with another inductor for inductive power transfer to occur.

2. The power transfer system as recited in claim 1, wherein the said at least one mobile inductors are mobile within a housing.

3. The power transfer system as recited in claim 2, wherein said external housing does not change shape when the at least one mobile inductor(s) moves.

4. The power transfer as recited in claim 3, wherein said housing has a thin flat external wall, and wherein said at least one mobile inductor moves along the inner surface of said external wall, in order to seek alignment with an inductor placed in proximity to the external surface of said external wall.

5. The power transfer system as recited in claim 4, wherein there is a broad flat cavity parallel to said external wall, the upper bound of which is the inner side of said external wall, and the lower bound of said broad flat cavity is a second parallel external wall, configured to provide space for movement of said at least one mobile inductor.

6. The power transfer system as in claim 5 wherein said second parallel external wall may rest upon any existing surface.

7. A power transfer system, including power connection means, said system with at least one inductor in which said at least one inductor is mobile such as to achieve alignment with another inductor for inductive power transfer to occur wherein there is at least one sensor which can detect proximity and relative direction of a mating inductor, said sensor connected to and controlling at least one motion causing means so as to move at least one of said mobile inductor(s) into effective alignment with said mating inductor so that inductive power transfer may occur.

8. The power transfer system of claim 7, wherein said motion sensors are placed within or adjacent to said at least one mobile inductor.

9. The power transfer system of claim 1, wherein said power connection means to each said at least one mobile inductor(s) is a wire connected to the power supply or load.

10. The power transfer of claim 1, wherein said power connection means to each mobile inductor is at least one brush or sliding electrical contact

11. The power transfer system as recited in claim 10, wherein said brushes or sliding electrical contacts slide-ably make electrical contact with the said inner surfaces of the said housing in which surfaces are conductive and connected to said power supply or load.

12. The power transfer system as recited in claim 11, wherein both inner surfaces of said housing are conductive, and are assigned polarity so as to establish a circuit with those of said mobile inductors which are energized.

13. The power transfer system as recited in claim 1, wherein there is only one electrical connection to each mobile inductor.

14. The power transfer system as recited in claim 7, wherein said motion causing means is non-mechanical.

15. The power transfer system as recited in claim 11, wherein all of said mobile inductors which are energized are effectively connected in parallel.

16. The power transfer system as recited in claim 1, wherein there is at least one capacitor connected to each of said mobile inductors.

17. A power transfer system which includes a power connection means and at least one mobile inductor, which is also a flexible inductor wherein said flexible inductor which is sufficiently flexible so as to be able to allow at least a portion of its length to bend and migrate so as to achieve alignment with another inductor for inductive power transfer.

18. The power transfer system as recited in claim 17, further including a housing, wherein said flexible inductor is free to move within said housing.

19. A power transfer system as recited in claim 17, said flexible inductor being self-reconfigurable due to the properties of said at least one flexible inductor, said properties so as to optimize inductance at a given region with a mating inductor.

20. The power transfer system as recited in claim 17, wherein said flexible inductor is capable of actively changing its shape.

21. The power transfer system as recited in claim 1, wherein each mobile inductor includes a switch, said switch operable in the effective presence of a mated secondary inductor seeking power transfer.