Energy harvesting

Abstract

The present disclosure provides an energy harvesting system for a wheel of a vehicle. The energy harvesting system comprises a linear inductive generator and a position sensor. The linear inductive generator is configured to extend substantially radially, in use, between a rim of the wheel and a portion of a tire mountable around the rim. The linear inductive generator comprises a first and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy. The position sensor is configured to detect a change in position of the first component relative to the second component for use in controlling the energy harvesting system.

Description

[0001] ENERGY HARVESTING

[0002] Technical Field

[0003] The invention relates generally to an energy harvesting system and method of harvesting energy.

[0004] Particularly, but not exclusively, the invention relates to an energy harvesting system for a wheel of a vehicle, the energy harvesting system comprising a linear inductive generator for harvesting energy in response to deformation of a portion of a tire of the wheel.

[0005] In the pursuit of extending the driving range and improving the energy efficiency of vehicles, e.g. electric and hybrid vehicles, various energy recovery methods have been explored. Traditional regenerative braking systems are commonly employed to recapture kinetic energy; however, additional avenues for energy harvesting remain underutilized. Existing approaches, such as embedding piezoelectric materials within tires, have demonstrated limited efficiency and scalability due to material constraints and integration challenges.

[0006] Aspects and embodiments of the present invention have been devised with the foregoing in mind.

[0007] of the Invention

[0008] The present invention addresses the limitations of the prior art systems by introducing an energy harvesting system comprising a linear electricity generator system (preferably a coil and magnet-based linear electricity generator system) that effectively converts tire deformation (compression and / or decompression) into electrical energy without compromising tire and vehicle performance. A tire fits on the rim of the wheel of on road and off-road vehicles such as passenger cars, truck and buses, etc. Due to the weight of the vehicle, tires are compressed causing creation of a flat surface against the road, referred to herein as a tire contact patch or contact patch area. This contact patch provides the traction between the tire outer surface and road surface. As the wheel rotates, the contact patch area is replaced by new contact patch area and the old contact patch area of the tire is decompressed as tire pressure inside the tire pushes the old contact patch out. The tire surface is deforming continuously while moving. This compression and decompression cycle is used in the present disclosure for harvesting energy. The inner surface of the tire can be interfaced to the energy harvesting system that can be integrated with the rim of the wheel.

[0009] Aspects and embodiments of the present invention are set out in the appended claims. These and other aspects and embodiments of the invention are also described herein.

[0010] According to an aspect of the invention, there is provided a linear inductive generator for a wheel of a vehicle. The linear inductive generator is configured to extend substantially radially, in use, between a rim of the wheeland a portion of a tire mountable around the rim. The linear inductive generator comprises a first and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy.

[0011] According to a further aspect of the invention, there is provided an energy harvesting system for a wheel of a vehicle comprising the linear inductive generator of the previous aspect. Preferably, the energy harvesting system further comprises a position sensor configured to detect a change in position of the first component relative to the second component for use in controlling the energy harvesting system.

[0012] Preferably, the energy harvesting system further comprises a control unit configured to receive an output signal from the position sensor corresponding to a change in position of the first component. Preferably, the position sensor comprises a magnetic sensor device.

[0013] Preferably, the control unit is further configured to selectively activate an output circuit of the linear inductive generatorto enable energy harvesting based on the received output signal. Preferably, the control unit is further configured to: determine, based on the output signal, that the deformation corresponds to a decompression of the portion of the tire; and activate an output circuit of the linear inductive generator during decompression of the portion of the tire to enable energy harvesting. Preferably, activating the output circuit of the linear inductive generator comprises adjusting a circuit component, state or property of the output circuit to enable energy harvesting.

[0014] Preferably, the control unit is further configured to: determine, based on the output signal, that the deformation corresponds to a compression of the portion of the tire; and deactivate an output circuit of the linear inductive generator during compression of the portion of the tire to limit energy harvesting. Preferably, deactivating the output circuit of the linear inductive generator comprises adjusting a circuit component, state or property of the output circuit to limit or (substantially) prevent energy harvesting. Preferably, the circuit component is a switch, and / or the property is a resistance of the circuit components (e.g. changing between an infinite or high load resistance and a low load resistance).

[0015] Preferably, the first component is configured to move from a retracted position to an extended position in response to decompression of the portion of the tire, and from the extended position to the retracted position in response to compression of the portion of the tire. Preferably, the retracted position is a more radially inward position relative to the extended position.

[0016] Preferably, the control unit is further configured to: communicate with an electronic control unit of a vehicle; receive one or more driving condition signals from the electronic control unit; and control an output circuit of the linear inductive generator based on the one or more driving condition signals.Preferably, the one or more driving condition signals indicate one or more of: deceleration of the vehicle; braking of the vehicle; application of drive to a, or the, wheel of the vehicle; and / or vehicle inclination.

[0017] Preferably, controlling the output circuit comprises enabling energy harvesting by activating the output circuit and / or disabling energy harvesting by deactivating the output circuit.

[0018] Preferably, the second component comprises a coil mountable to or in the rim of the wheel; and the first component comprises a plunger configured to extend from the second component to the portion of the tire, the plunger comprising one or more magnets at an end proximate the second component. Preferably, the plunger extends in a radial direction.

[0019] Preferably, the linear inductive generator comprises a pad (or an additional patch or base portion) coupled to an end of the first component, e.g. the end proximate the portion of the tire in use. The pad is preferably configured to releasably contact an inner surface of the portion of the tire. Preferably, releasable contact refers to an abutment and / or frictional engagement of the pad with the inner surface of the tire. The pad may have a width and a length. The length is in the circumferential direction of the wheel, and the width is in a perpendicular direction, e.g. an axial direction. The width may be substantially greater than the length. The width may be configured, in use, to extend across, or substantially match, the width of the tire contact patch.

[0020] According to a further aspect of the invention, there is provided an energy harvesting system for a wheel of a vehicle. The energy harvesting system comprises a linear inductive generator configured to extend substantially radially, in use, between a rim of the wheel and a portion of a tire mountable around the rim. The linear inductive generator comprises a first and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy. The linear inductive generator further comprises a pad coupled to an end of the first component proximate the portion of the tire in use, the pad configured to releasably contact an inner surface of the portion of the tire. Preferably, the pad is rotatably coupled to the end of the first component, preferably via a ball joint arrangement.

[0021] Preferably, the control unit is further configured to determine, based on the output signal from the position sensor, that the tire is at least partially deflated. Preferably, the control unit is further configured to determine that the tire is at least partially deflated based on the output signal meeting a threshold condition. Preferably, in response to determining that the tire is at least partially deflated, the control unit is configured to energize the linear inductive generator to cause the first component to move towards the second component and thereby retract the first component away from the tire in use.

[0022] Preferably, the energy harvesting system further comprises a wireless transmitter connectable to an output circuit of the linear inductive generator for receiving and transmitting energy harvested therefrom; and a wireless receiver connectable to a part of a vehicle body, preferably connectable to a brake caliper of the wheel, for receiving energy transmitted from the wireless transmitter.According to a further aspect of the invention, there is provided an energy harvesting system for a wheel of a vehicle, the energy harvesting system comprising: a linear inductive generator configured to extend substantially radially, in use, between a rim of the wheel and a portion of a tire mountable around the rim, the linear inductive generator comprising a first and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy; a wireless transmitter connectable to an output circuit of the linear inductive generator for receiving and transmitting energy harvested therefrom; and a wireless receiver connectable to a part of a vehicle body, preferably connectable to a brake caliper of the wheel, for receiving said energy transmitted from the wireless transmitter.

[0023] Preferably, the wireless receiver is electrically connectable to a vehicle power circuit to supply said harvested energy to the vehicle. Preferably, the wireless receiver is electrically connectable to a high-voltage power distribution unit of the vehicle for supplying said harvested energy to a motor unit of the vehicle. Preferably, the wireless receiver comprises or is electrically connectable to a voltage converter unit for converting said harvested energy to a high-voltage or low-voltage direct current. Preferably, the wireless receiver is electrically connectable to a voltage converter unit of the vehicle for matching a voltage level of said harvested energy to a voltage level of a battery of the vehicle.

[0024] Preferably, in use, the wireless transmitter is configured to be attached to the wheel. Preferably, the wireless transmitter is configured to convert the received harvested energy into a high-frequency signal before transmitting said high-frequency signal to the wireless receiver.

[0025] According to a further aspect of the invention, there is provided a wheel assembly, comprising: a wheel for a vehicle; and an energy harvesting system according to any of the above aspects, wherein the linear inductive generator extends substantially radially from a rim of the wheel.

[0026] Preferably, the wheel assembly further comprises the tire mounted around the wheel, Preferably, the linear inductive generator extends between the rim and a portion of the tire. Preferably, the wheel assembly further comprises a plurality of said linear inductive generators distributed circumferentially around the rim. Preferably, the plurality of linear inductive generators comprises at least 20 linear inductive generators, more preferably at least 25 linear inductive generators, further preferably at least 30 linear inductive generators, further preferably at least 60 generators (e.g. for heavy travelling vehicles (HTVs).

[0027] Preferably, the second component comprises a coil and is embedded in, and / or mounted within a recess of, the rim of the wheel, such that the coil is in thermal contact with the rim.

[0028] According to a further aspect of the invention, there is provided a wheel assembly, comprising: a wheel for a vehicle; and an energy harvesting system for integration with the wheel, wherein the energy harvesting systemcomprises: a linear inductive generator configured to extend substantially radially, in use, between a rim of the wheel and a portion of a tire mountable around the rim, the linear inductive generator comprising a first and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy; and wherein the second component comprises a coil and is embedded in, and / or mounted within a recess of, the rim of the wheel, such that the coil is in thermal contact with the rim.

[0029] According to a further aspect of the invention, there is provided a vehicle comprising the energy harvesting system of any of the above aspects and / or comprising the wheel assembly of any of the above aspects.

[0030] Preferably, the energy harvesting system comprises a control unit in communication with an electronic control unit of the vehicle, the control unit configured to control an output circuit of the linear inductive generator based on one or more driving condition signals received from the electronic control unit of the vehicle. Preferably, the one or more driving condition signals indicate one or more of: deceleration of the vehicle; braking of the vehicle; application of drive to a, or the, wheel of the vehicle; and / or vehicle inclination.

[0031] According to a further aspect of the invention, there is provided a method of harvesting energy from a wheel of a vehicle using a linear inductive generator, the linear inductive generator extending substantially radially between the rim of the wheel and a portion of a tire mounted on the rim, the linear inductive generator comprising a first and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy, the method comprising: determining, based on an output signal of a position sensor configured to detect a change in position of the first component relative to the second component, that an activation condition for activating an output circuit of the linear inductive generator is met; and selectively activating the output circuit of the linear inductive generator to enable energy harvesting based on the determination, preferably wherein determining the activation condition comprises: processing, by a control unit, the output signal of the position sensor corresponding to a change in position of the first component to determine whether the change in position corresponds to decompression of the portion of the tire.

[0032] According to a further aspect of the invention, there is provided a method of harvesting energy from a wheel of a vehicle using a linear inductive generator, the linear inductive generator extending substantially radially between the rim of the wheel and a portion of a tire mounted on the rim, the linear inductive generator comprising a first and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy, the method comprising: activating an output circuit of the linear inductive generatorto enable energy harvesting; and transmitting, using a wireless transmitter, the harvested energy from the output circuit of the linear inductive generatorto a wireless receiver located proximate the wireless transmitter, preferably located on a brake caliper of the wheel, for supplying to the vehicle; and preferably transmitting said harvested energy from the wireless receiver to anelectronic circuit component for use by the vehicle, preferably wherein the electronic circuit component is configured to match an output voltage of the harvested energy to a voltage of a battery of the vehicle.

[0033] According to a further aspect of the invention, there is provided a method of harvesting energy from a wheel of a vehicle using a linear inductive generator, the linear inductive generator extending substantially radially between the rim of the wheel and a portion of a tire mounted on the rim, the linear inductive generator comprising a first and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy, the method comprising: controlling an output circuit of the linear inductive generator to control energy harvesting based on one or more driving condition signals received from an electronic control unit of the vehicle.

[0034] Preferably the one or more driving condition signals indicate one or more of: deceleration of the vehicle; braking of the vehicle; application of drive to a, or the, wheel of the vehicle; and / or vehicle inclination.

[0035] Preferably, the tire is compressible. As used herein, the term “rotatable” is used generally interchangeable with the term “pivotable”.

[0036] Aspects of the present disclosure provide a vehicle energy harvesting system comprising linear electricity generator and plungers embedded in a wheel rim to generate electricity from tire compression and decompression.

[0037] Aspects of the present disclosure provide a pad or additional patch with a ball joint with plunger that allows the pad / additional patch to stay in contact with inner surface even when road surface is not even. Ball joints may give 360-degree freedom for pad / additional patch to move along with inner surface of the tire. In some examples, the pad / additional patch can be attached to the inner surface of the tire either by adhesive or other methods, such as interlocking with additional patch by permanently pasting to tire inner surface to interlock the tire inner surface with the additional patch on the plunger. In preferred examples, the pad releasably contacts but is not affixed to the inner surface of the tire (as described previously). For example, the pad is held in place by the centrifugal force acting on the pad via the linear inductive generator and preferably also by the air pressure of the tire.

[0038] The ball joint between the pad / additional patch and plunger is preferably designed in such a way that it allows for easy removal from the joint, e.g. so that the plungers can be removed during tire change. Pad / additional patch can be designed as use and through material.

[0039] Aspects of the present disclosure provide a wireless energy transfer system integrated into the wheel for instantaneous power transmission to the vehicle battery.Aspects of the present disclosure provide a collapsible plunger mechanism that prevents mechanical damage in flat tire scenarios.

[0040] Aspects of the present disclosure provide a thermal management system which utilizes passive cooling from wheel rotation to dissipate heat.

[0041] Aspects of the present disclosure provide a modular design allowing scalability in electric and hybrid vehicles.

[0042] Various aspects of the present disclosure relate generally to an energy harvesting system that utilizes tire compression and decompression forces to harvest electrical energy. The system preferably integrates large number of linear electricity generators and plungers within a vehicle’s wheel rims, converting tire’s mechanical compression and decompression into electrical energy. Wireless energy transfer eliminates the need for inwheel storage, and a passive thermal management system ensures optimal performance. The invention provides a scalable solution for extending the driving range of electric vehicles while minimizing additional weight and complexity. This invention may help to reduce the cost of electric vehicles (EV) by supplementing the power to the high voltage (HV) battery packs in the vehicle. Due to the range boost, the battery pack size can be reduced for same original range. This invention may also help to reduce the running cost of a vehicle as range boost causes less discharge of battery pack hence less payment for battery charging.

[0043] Any system or device feature as described herein may also be provided as a method feature, and vice versa. As used herein, means plus function features may be expressed alternatively in terms of their corresponding structure. Any, some and / or all features in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination or sub-combination. In particular, device aspects may be applied to method aspects, and vice versa. It should also be appreciated that particular combinations of the various features described and defined in any aspect of the invention can be implemented and / or supplied and / or used independently. The invention extends to methods, systems and devices substantially as herein described and / or as illustrated with reference to the accompanying figures. The invention also extends to any novel aspects or features described and / or illustrated herein.

[0044] In this specification the word 'or' can be interpreted in the exclusive or inclusive sense unless stated otherwise. Whilst the invention has been described in the context of memory, it can also be implemented in any field of use where a device with switchable resistance states is required, either on an individual scale or in a large-scale array of devices.

[0045] Brief Description of Drawings

[0046] In order that the invention can be well understood, embodiments will now be discussed byway of example only with reference to the accompanying drawings, in which:Figure 1(a) shows a schematic diagram of an energy harvesting system in accordance with the disclosure;

[0047] Figure 1 (b) shows a schematic diagram of an energy harvesting system in accordance with the disclosure;

[0048] Figure 1(c) shows a schematic diagram of a wheel assembly in accordance with some embodiments of the disclosure;

[0049] Figure 1(d) shows a method of harvesting energy in accordance with some embodiments of the disclosure;

[0050] Figures 2(a) - 2(c) show different schematic views of a tire which illustrate tire compression and decompression locations and forces available for energy harvesting in accordance with the disclosure;

[0051] Figures 3(a) - 3(b) show isometric and front views of a wheel assembly and a wireless power transfer system in accordance with some embodiments of the disclosure;

[0052] Figure 3(c) shows a method of harvesting energy in accordance with some embodiments of the disclosure;

[0053] Figure 4 shows a front view of an assembly of a rim and a plurality of linear inductive generators in accordance with the disclosure;

[0054] Figures 5(a) - 5(b) show side and isometric views of the assembly of figure 4;

[0055] Figures 6(a) - 6(b) show side and cross-sectional views of an energy harvesting system in accordance with the disclosure;

[0056] Figure 7 shows an isometric view of the energy harvesting system of figure 6;

[0057] Figures 8 - 10 show partially exploded views of an energy harvesting system comprising a wheel assembly and a wireless power transfer system in accordance with the disclosure;

[0058] Figures 11(a) - 11(c) show exploded views of linear inductive electricity generator in accordance with the disclosure;

[0059] Figures 12(a) - 12(b) show side and isometric views respectively of a wireless power transfer assembly in accordance with the disclosure;

[0060] Figures 13 shows an exploded view of a wireless power transfer assembly in accordance with the disclosure;

[0061] Figure 14 shows a schematic diagram of a vehicle comprising an energy harvesting system in accordance with the disclosure;

[0062] Figures 15(a) - 15(b) show cross-sectional views of an energy harvesting system in accordance with the disclosure; and

[0063] Figure 16 shows a flowchart of a method of operating a linear inductive generator in accordance with the disclosure.

[0064] It should be noted that the figures are diagrammatic and may not be drawn to scale. Relative dimensions and proportions of parts of these figures may have been shown exaggerated or reduced in size, for the sake of clarity and convenience in the drawings. The same reference signs are generally used to refer to corresponding or similar features in modified and / or different embodiments.

[0065] Detailed

[0066] The present disclosure relates to an energy harvesting system comprising various features that together or in various combinations can recover / harness energy from a wheel of a vehicle in an improved manner forextending the driving range and improving efficiency of the vehicle, while limiting the impact on tire and vehicle performance. In preferred embodiments, the present disclosure uses a coil and permanent magnet-based linear electricity generator system that can effectively convert tire deformation (compression and / decompression) into electrical energy without compromising tire and vehicle performance. Furthermore, the present disclosure provides a mechanism for direct wireless power transfer of the recovered energy to the vehicle without needing a dedicated battery, thereby reducing the weight of the overall energy harvesting system.

[0067] With reference to figures 2(a) to 2(c), vehicle tires 2 are typically fitted on the rim of the wheel of on road and off-road vehicles such as passenger cars, truck and buses, etc. Due to the weight of the vehicle (e.g. indicated by arrow 22) which acts on the axel 21 , tires are compressed, thereby causing a creation of a flat portion of the tire contacting the road. This flat portion is referred to herein as a contact patch 24 of the tire. This contact patch 24 provides the traction between the tire outer surface and road surface. As the wheel rotates, the contact patch area is replaced by a new contact patch area and the previous contact patch area of the tire is decompressed as the internal air pressure inside the tire applies a centrifugal force to restore the shape of the previous contact patch. Thus, the tire surface is in a constant state of deformation due to compression of a new contact patch and decompression of a previous contact patch while the vehicle is moving.

[0068] The present invention aims to harness energy from this compression and decompression of the tire. The inner surface of the tire is interfaced to an energy harvesting system that is integrated to a rim of the wheel. In other words, the present invention relates to an energy harvesting system that utilizes the compression and decompression cycles of a vehicle’s tire to generate electrical energy. Specifically, the invention describes a method of embedding linear electricity generators inside the wheel assembly to convert mechanical deformation of the tire into usable electrical energy. This harvested energy can then be transmitted for use in other parts of the vehicle, for example to be used by a motor to extend the driving range of the vehicle. The objective of this design is to harvest energy for useful range-boost in the Electric Vehicle (EV).

[0069] In some embodiments, the present disclosure provides devices and systems for converting deformation forces on a tire to electricity using stationary coils and moving magnets integrated into the rim of vehicle. A plunger is interfaced with a tire inner surface and magnet. An additional patch (also referred to as a pad) of certain area is added between the plunger and tire surface for uniform distribution of forces. A set of coil, magnet, plunger and the pad (i.e. the additional patch) will be referred to as generator in this disclosure. Preferably, a (large) number of generators are integrated into the rim of the wheel and interfaced to tire inner surface so that less force is consumed for energy harvesting reducing stress on the tire, not affecting vehicle performance and stability I safety. Every time the tire is compressed, it causes the magnet to be pushed inside the coil, and the magnet is pulled outwhile the tire is decompressing due to the centrifugal force of moving mass of the generator assembly. This magnet movement in the coil causes electromagnetic induction leading to electricity generation. While vehicle is moving, the tire rotates leading to repeated cycles of compression and decompression. The speed of repetition depends on vehicle speed or wheel speed.In preferred embodiments, the electricity generated by each generator is conditioned and wirelessly transferred to vehicle. In the vehicle, it can be further conditioned to match the voltage levels of the high voltage (HV) bus used for delivering HV power to a traction motor inverter from the vehicle’s HV battery pack. Accordingly, the system of the present can advantageously generate and allow to use energy for the propulsion at the same time.

[0070] The design of the system can ensure minimal impact on the wheel's mass and balance and preferably includes safety features to prevent damage during tire deflation scenarios, as described in more detail below.

[0071] The following basic calculations show how energy harvested provides useful range boost. Useful range boost is sufficiently higher to accommodate the cost of the product in the vehicle. Figure 2(a) shows the compression and decompression in tires.

[0072] Assumptions: Vehicle = Tesla Model 3, Vehicle; mass (mv) = 2500 Kg; number of wheels (N) = 4; mass per wheel (mw) = 625 Kg; tire pressure = 42 psi (289580 pa); tire circumference (C) = 2m; energy Consumption Rate (ECR) = 92.3 Wh / km; gravitational acceleration (g) = 9.81 m / s2; tire contact patch area (A) = 150 cm2; tire compression (D) = 10mm; efficiency of energy harvester (n) = 50%; vehicle speed (v) = 60 km / h.

[0073] Energy available per wheel per revolution or cycle for energy harvesting: compression force, Fc = mw x g = 6131.25 N; decompression force, Fd = P x A=4343.7 N; total force, Ft = Fc + Fd = 10474.95 N; energy available, Ea = Ft x D = 104.75 J; total energy available from all tires, EaTotal = Ea x N = 418.998 J.

[0074] Embodiments of the system described herein can address several technical challenges, including one or more of: (1) efficient conversion of tire compression and decompression into electrical energy without significantly increasing unsprang mass or affecting vehicle dynamics; (2) optimization of generator design to maximize energy output while ensuring durability under continuous mechanical stress; (3) effective thermal management to dissipate heat generated during energy conversion; (4) reliable wireless transmission of the harvested energy to the vehicle's power system with minimal losses; and (5) implementation of safety mechanisms to protect the system during tire deflation or puncture events.

[0075] Embodiments of the system described herein can address these challenges by providing one or more of:

[0076] Compression-based energy harvesting: plungers connected to flexible tire contact patches and / or pads move into generator coils as the tire deforms, which can be used to induce an electric current;

[0077] Decompression-based energy harvesting: as the tire regains shape, the plungers retract, generating energy;

[0078] Optimized force distribution: instead of a single I few large generators, preferably multiple smaller solenoids (e.g., 30 per wheel) are used to ensure even force distribution;Adaptive tire pressure: a slight increase in air pressure compensates for force consumed during energy harvesting, ensuring optimal contact patch size. For example, a tire pressure for a wheel assembly incorporating the energy harvesting system is set at a higher value as compared to a wheel without the disclosed energy harvesting system;

[0079] Design optimization: the solenoid-plunger assemblies are preferably constructed using lightweight, high- strength materials to minimize additional un-sprung mass, and computational simulations and physical testing can be employed to determine the optimal number and placement of solenoids within the wheel rim, balancing energy output with structural integrity;

[0080] Energy conversion efficiency: the plunger stroke length and generator coil parameters is preferably precisely engineered to align with the tire's deformation characteristics, ensuring maximum electromagnetic induction during each compression and decompression cycle;

[0081] Thermal management: components related to generators and wireless power transfer are preferably integrated into the rim so that rim can be used as heat sink. The system can also leverage the natural airflow around the rotating wheel to facilitate passive cooling. Additionally, heat-dissipating materials and surface treatments can be applied to critical components to enhance thermal performance;

[0082] Wireless energy transmission: a resonant inductive coupling method is preferably utilized for wireless energy transfer, employing a caliper-disc-inspired alignment mechanism to maintain a consistent minimal airgap, thereby reducing transmission losses;

[0083] Safety Features: the plunger mechanisms are preferably configured to retract fully into their housing in the event of a tire deflation, preventing damage to both the energy harvesting system and the tire structure.

[0084] Embodiments of the system described herein can provide several advantageous effects, including one or more of the following:

[0085] Enhanced energy recovery: the system can utilizes both compression and decompression cycles, maximizing energy extraction;

[0086] Continuous energy harvesting: the system can provide a constant source of electrical energy during vehicle operation, supplementing existing power systems without additional fuel consumption;

[0087] Non-intrusive integration: the design can be integrated seamlessly into existing wheel assemblies without adversely affecting vehicle handling or comfort;

[0088] Scalability: the number of solenoids can be adjusted to balance energy output and system complexity. The modular nature of the system allows for adaptation across various vehicle types and sizes, from passenger cars to heavy-duty trucks;

[0089] Enhanced vehicle efficiency: by harnessing energy that would otherwise be wasted, the system can contribute to overall vehicle energy efficiency and can extend the operational range of electric vehicles; Wireless power transfer: the harvested energy is preferably transferred via an inductive coupling system, reducing the need for a dedicated electrical rotary connector or physical wiring;

[0090] Performance of tire and vehicle: only part of the gravitational force due to vehicle mass and gravitational acceleration is consumed for energy harvesting, there is no adverse effect on the performance of tire, vehicle or safety. This can be achieved by distributing this force to preferably 30+ sets of coil / magnetassemblies to harvest energy; Furthermore, the movable component (i.e. plunger assembly) of the generator is substantially prevented from moving beyond the circumference of the fully inflated tire. This can limit the overall stress on the tire from the energy harvesting system. Specifically, this constraint on the range of motion of the plunger assembly can ensure that a portion of the tire which is not deformed (and / or is in a decompressed state) may not experience stress due to a transfer of centrifugal force from the movable component to the tire portion.

[0091] Thermal management: coils and magnets used to harvest energy are preferably integrated into the rim of the wheel. The rim works like heat sink. No additional thermal management is required. Additionally, air channels (not shown) can be planned on the rim for using air flowing while vehicle is in motion for thermal management. This can result in saving space, additional un-sprung mass and cost of additional thermal management materials;

[0092] Wireless energy transfer: harvested energy is preferably wirelessly transferred to the vehicle, avoiding the challenges of conductive energy transfer from rotating tire to vehicle. Two sets of coils are required: a transmitter coil transmits power to a receiver coil. The transmitter coil is preferably integrated to the rim hence can solve the space, weight issue and thermal management issue. The associated power electronics (associated with the transmitter and / or receiver) are preferably powered by the energy harvested. The receiver coil receives the power from the transmitter coil. The receiver coil is preferably mounted-on brake caliper to maintain constant distance between the transmitter and receiver coils. The associated power electronics is again preferably powered by the energy harvested. Startup energy can be sourced from the vehicle, or, alternatively, in preferred examples, once the vehicle starts moving, the energy harvesting system, wireless energy transfer system and / or associated power electronics receive power from generators to power itself.

[0093] Using received energy: received energy is preferably conditioned to match the vehicle’s (EV) HV bus voltage level. Preferably, this conditioned energy is not stored in the vehicle’s primary battery or secondary battery, instead it is fed to the HV bus to be consumed by propulsion in real time. As the harvested energy is not stored there is no impact on vehicle weight and performance. By providing this additional energy from the energy harvesting system to propulsion system of vehicle, the vehicle uses less energy from battery pack for propelling the vehicle leading to boosted range.

[0094] Impact of range boost: achieved range boost helps either to achieve longer overall range for electrical vehicle (EV) or for the same range of vehicle, reduce the battery capacity hence weight of vehicle. This can reduce: (a) the cost of vehicle while maintaining the same range; (b) the cost of charging the vehicle every time (i.e. running cost); and / or (c) load on the power grid / charging stations.

[0095]

[0096] Figure 1(a) shows an energy harvesting system 100 for a wheel of a vehicle. The energy harvesting system 100 comprises a linear inductive generator 1 and preferably a position sensor 9. The linear inductive generator 1 is configured to extend substantially radially, in use, between a rim of the wheel and a portion of a tiremountable around the rim. For ease of explanation, the wheel and tire is omitted from the schematic diagram of Figure 1(a) and these components are introduced in later figures (e.g. Figure 1(c) and Figure 3(b)).

[0097] The linear inductive generator 1 comprises a first component and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy. The position sensor 9 is configured to detect a change in position of the first component relative to the second component for use in controlling the energy harvesting system. In one or more embodiments, the second component of the linear inductive generator 100 comprises a coil 16 mountable to or in the rim of the wheel and the first component comprises a plunger 14 configured to extend from the second component to the portion of the tire. The plunger 14 comprises one or more magnets 15 at an end of the plunger 14 proximate the second component. The linear inductive generator 100 further comprises a pad (or additional patch) 11 coupled to an end of the first component proximate the portion of the tire in use. The pad 11 is configured to releasably contact an inner surface of the portion of the tire. The pad 11 is rotatably coupled to the end of the first component, preferably via a ball joint arrangement. The ball joint arrangement comprises a ball 13 coupled to the end of the first component proximate the pad 11 (i.e. the portion of the tire in use) and a ball socket 12 provided on the pad 11 for receiving the ball 13.

[0098] The position sensor 9 is located proximate the first component, for example proximate the magnet 15 and is thus configured to sense the position of the magnet 15. For example, sensor 9 may be located in a recessed portion or housing of the rim proximate the coil 16. In one or more embodiments, sensor 9 is a magnetic sensor device (e.g. a hall sensor). As disclosed herein, the sensor 9 can detect a change in position of the first component and generate an output signal for selectively enabling energy harvesting.

[0099] In one or more embodiments, the energy harvesting system 100 further comprises a control unit 80. Control unit 80 is configured to receive the output signal from the position sensor 9 corresponding to a change in position of the first component. Control unit 80 is further configured to selectively activate an output circuit of the linear inductive generator 1 to enable energy harvesting based on the received output signal.

[0100] Control unit 80 can be integrated into the energy harvesting system 100, e.g. by being located proximate the linear inductive generator 1 and / or sensor 9. In one or more embodiments, control unit 80 is integrated into the electronics hardware 31 of a wireless power transmitter located in the wheel.

[0101] Control unit 80 can be configured to communicate wirelessly with the sensor 9. Alternatively, in preferred examples, the sensor 9 is connected to the control unit 80 via one or more wires. Furthermore, as will be described further, control unit 80 is configured to wirelessly communicate with the vehicle ECU, e.g. to receive one or more driving condition signals from the ECU of the vehicle. For example, control unit 80 can be integrated into the wheel and can wirelessly receive the one or more driving condition signals from the vehicle ECU (e.g. using the Qi2 standard protocol or other such known protocols for wireless communication).In use, the linear inductive generator 1 is configured to be integrated between the rim and tire of a wheel of a vehicle. In particular, generator 1 extends inwards in a substantially radial direction from a portion of the tire towards the rim, such that the pad 11 contacts an inner surface of the tire. Pad 11 releasably contacts the inner surface of the tire and is configured to have a degree of freedom of movement relative to the inner surface of the tire.

[0102] Pad 11 may be held in position via counteracting forces acting on the pad 11 , e.g. from the pressure of the tire and / or a centrifugal force acting on the plunger 14. Additionally or alternatively, an adhesive or interlocking mechanism may be used to attach the pad 11 to the inner surface ofthe tire while permitting a degree of floating of the pad 11 in use. The forces acting on the generator 1 are described below with reference to a plunger assembly comprising the pad 11 , socket 12, ball 13, plunger 14 and magnet 15. The plunger assembly comprises the moving parts / mass ofthe generator 1 and the coil 16 comprises the relatively stationary part of the generator 1.

[0103] As the tire contact patch begins to compress due to a normal force acting on the tire from the road surface, the tire surface transfers the normal force to the plunger assembly. Accordingly, plunger assembly is pushed towards the center of the wheel, leading to movement of the magnet 15 into the coil 16 (i.e. the space circumferentially surrounded by the coil 16). This movement of the magnet 15 causes a change in magnetic flux through the coil 16 leading to electrical voltage induction in the coil 16. This inductive energy can (selectively) be harvested while tire is being compressed.

[0104] Furthermore, when the plunger assembly reaches the end of the compression, i.e. the center of the contact patch length on the tire surface which contacts the road surface, the plunger assembly has stopped moving towards the center ofthe wheel and now stores the potential energy due to centrifugal force generated by the mass ofthe plunger assembly and the rotation ofthe wheel. Effectively, the plunger assembly in this state acts as a preloaded spring. Accordingly, when the tire is being decompressed, the plunger assembly starts moving back outwards due to the centrifugal force acting on it. The outward movement ofthe magnet 15 relative to the coil 16 causes induced voltage in the coil 16 which is then used for energy harvesting, as explained in further detail below. Furthermore, as discussed later in the specification, the voltage induction can further give rise to Lorentz forces which, in some instances, may impact the rolling resistance ofthe vehicle.

[0105] Plunger 14 extends radially inwards from a first end to a second end, i.e. from the ball socket 12 ofthe pad 11 and towards the coil 16. A first end of plunger 14 proximate the tire (i.e. proximate the pad 11) comprises the ball 13 configured to be received by the ball socket 12. A second end of plunger 14 (i.e. proximate the wheel rim) comprises a magnet 15. The second end of plunger 15 is located proximate a coil 16. For example, coil 16 may be provided in a recess or housing inside or proximate the rim. Magnet 15 is thus configured to enter / exit the space surrounded by the coil 16.Linear inductive generator 1 is configured to generate electrical power by electromagnetic induction caused by the linear movement of the plunger 14 (and / or magnet 15) relative to the coil 16. As discussed below, this linear movement, i.e. a substantially radially inward and outward movement of the plunger 14, is triggered by the deformation of a wheel tire during use. In other words, generator 1 is arranged to harness and recover energy from tire compression and / or decompression during use.

[0106] The operation of the energy harvesting system 100 will now be described, additionally with reference to Figures 1(b) and 1(c). Figure 1(b) shows an energy harvesting system 100-a comprising a plurality of linear inductive generators 1 , including generators 1-n, 1-a, 1-b, 1-c and 1-m, configured to be distributed circumferentially around a rim of a wheel. Figure 1(c) shows a wheel assembly 200 comprising a wheel for a vehicle; and the energy harvesting system 100-a as previously described above. For ease of viewing, labelling of repeated features (e.g. the labelling of each generator 1 in the plurality of generators 1) has been removed but it will be understood that such identical features have substantially the same components and functionality. Furthermore, for ease of explanation, position sensor 9 is not shown in Figures 1 (b) and 1 (c) but it will be understood that a sensor 9 corresponding to each generator 1 of the plurality of generators 1 is present in the assembly 100-a and 200.

[0107] The linear inductive generators 1 each extend substantially radially from a rim 7 of the wheel. Preferably, the wheel assembly 200 further comprises a tire 2 (not shown in Figure 1 (c)) mounted around the wheel, and each linear inductive generator 1 extends between the rim 7 and a portion of the tire 2. For example, the tire 2 may be a tire as shown in Figures 2(a) - 2(c)).

[0108] Figures 1(b) and 1(c) show a state of the energy harvesting system 100-a in which the wheel is rotating (e.g. in a clockwise direction) as the vehicle moves. As the wheel rotates, a portion of the tire, also known as a contact patch of the tire, contacts the road (or other surface on which the vehicle is travelling). A normal force, which counters the weighing force of the vehicle distributed on the wheel, then acts in a substantially upwards direction on the tire contact patch, thereby compressing the portion of the tire corresponding to the contact patch. In other words, the tire contact patch is the specific area of a tire's tread that touches the road surface at any given moment. The contact patch is formed due to tire deformation and reformation (i.e. compression and decompression) due to the weight of the vehicle acting on the tire.

[0109] As the tire rotates further, the contact patch no longer contacts the road and is subsequently decompressed to substantially its original shape by a restorative force created by air pressure as well as the centrifugal force acting on the moving mass of the generator and subsequently transferred to the tire (i.e. to the contact patch). As a result of the centrifugal force, the contact patch is returned to its original shape fasterthan a contact patch of a regular tire (without the generators 1) undergoing hysteresis. At the same time, a further contact patch immediately preceding the patch (e.g. in a relatively counter-clockwise position to the contact patch) contacts the road and is compressed, and so on. Thus, as the wheel rotates, the tire is in a constant state of deformation (i.e. compression and decompression).Figure 1 (c) (and 1(b)) shows a plurality of linear inductive generators 1 (configured to be) distributed circumferentially around the rim 7. Preferably, the assembly 200 (or 100-a) comprises at least 20 linear inductive generators 1 , more preferably at least 25 or 30 linear inductive generators 1 . For example, the assembly 200 (or 100-a) comprises 30 linear inductive generators 1 as shown in Figures 1(b) and 1(c). The plurality of linear inductive generators 1 are spaced apart around the rim 7 for an equal distribution of weight of the generators 1 , thereby distributing the weighing and centrifugal force evenly to avoid adverse impact on the tire, and to ensure that a suitable number of generators 1 is actuated for harvesting energy at any given moment during rotation of the wheel. Furthermore, such a number of generators 1 can have the effect of spreading the centrifugal force due to moving mass around the wheel. The generators 1 can further lower the overall effect of rolling resistance due to the weight of the generators 1 ,as the generators 1 act as a preloaded spring to recover the tire’s original shape at a faster pace as compared to a tire not undergoing such transferred centrifugal force.

[0110] With reference to Figure 1(b), the plurality of linear inductive generators 1 comprises generators 1-a, 1-b and 1-c which are located on a first contact patch of the tire (i.e. the pads 11 of these generators 1-a, 1-b and 1-c contact the first contact patch). In the rotation state of Figure 1(b), the first contact patch is in contact with the road and is deformed, as described above. Owing to the arrangement of the linear inductive generators 1-a, 1-b and 1-c on the contact patch, the normal force acting on the contact patch is then conveyed to these generators 1-a, 1-b, 1-c. Specifically, as explained above, the normal force acts against the centrifugal force and internal air pressure in the wheel which maintains the plunger 14 in an extended state.

[0111] For example, as shown in Figure 1 (b), a first generator 1-n is arranged in a neutral state in which there is little or no normal force causing tire deformation acting on the generator 1-n. In other words, the plunger 14 of this generator 1-n is located outside of the tire contact patch with the driving / road surface and is held in its extended position by the centrifugal force due to the rotating wheel and moving mass of the plunger 14 (whereby the tire pressure maintains the neutral shape / state of the tire). This equilibrium of forces is gradually altered for a generator 1 as the wheel rotates and the corresponding portion of the tire comes into contact with the road (and becomes part of the tire contact patch).

[0112] In a first contact state, contact between the road surface and the corresponding portion of the tire is initiated, as depicted by generator 1-a, and the normal force causes the corresponding portion of the tire to deform and compress (this is referred to herein as tire compression). The normal force overcomes the centrifugal force acting on the plunger 14, thereby retracting the plunger 14 radially inwards. It will be appreciated that the centrifugal force is stored as potential energy by the plunger assembly which effectively behaves as a preloaded spring acting against the corresponding portion of the tire. Accordingly, the plunger 14 and magnet 15 are moved linearly (i.e. substantially radially inwards) relative to or towards the coil 16 to enable electromagnetic induction between the magnet 15 and coil 16. As discussed in more detail below, this inductive movement is only converted to electrical energy if the output circuit of the generator 1 is activated.As the tire rotates further, a second contact state, as depicted by generator 1-b, is attained in which the normal force acting on the corresponding portion of the tire, and on the plunger 14, is increased causing further (maximal) deformation / compression of the corresponding portion of the tire. In the second contact state, the plunger 14 further retracts further to its peak retracted position, as shown by the relatively inward position of the magnet 15 of the generator 1-b as compared to the position ofthe magnet 15 of generator 1 -a. The plunger assembly further stores a peak amount of potential energy in this state. It will be appreciated that the normal force distribution across the tire contact patch is peaked with a maximum that is generally aligned with the wheel centre (axis of rotation) when the wheel is stationary, and is (for compressible, e.g. rubber-based, tires) generally shifted forwards (relative to the direction of travel) when the wheel is rotating, as is known in the art.

[0113] Upon further tire rotation, a third contact state, as depicted by generator 1-c, is reached in which the normal force acting on the plunger 14 is decreased relative to the second contact state of generator 1-b causing (in combination with the internal tire pressure) reduced deformation / compression of the corresponding portion of the tire (this is referred to herein as tire decompression). Thus, the plunger 14 begins to extend substantially radially outwards due to the decrease in tire deformation / normal force and due to the centrifugal force acting on the plunger 14. In the third contact state, the plunger 14 extends, as shown by the relatively outward position ofthe magnet 15 ofthe generator 1-c as compared to the position ofthe magnet 15 of generator 1-b.

[0114] Eventually, upon further rotation, the corresponding portion of the tire no longer contacts the road and is substantially reformed (or decompressed to its neutral state), as shown by generator 1-m, and the plunger 14 returns to its extended state. In other words, the stored centrifugal force is released, thereby returning the plunger 14 to its initial extended position. The internal air pressure (and centrifugal force) also restores the portion of the tire to its initial neutral position / state. It will be appreciated that, during decompression, the centrifugal force acting on the plunger 14 causes the corresponding portion ofthe tire to decompress (return to its neutral state) faster than would be case if the generators were not present.

[0115] The movement ofthe plunger 14 from the neutral / extended position (e.g. the neutral state of generator 1-n) to a peak retracted position (e.g. the second contact state of generator 1-b) is referred to as the compression stroke (or upstroke). Accordingly, the movement ofthe plunger 14 from the peak retracted position back to the extended position (e.g. the neutral state of generator 1-m) is referred to as the decompression stroke (or downstroke).

[0116] In one or more embodiments, a pad 11 may be shared by neighboring generators 1 . For example, a batch of five or six neighboring generators 1 may share a continuous pad 11 (in other words, the pads 11 of these generators 1 may be integrally formed or connected, and substantially flexible).

[0117] Furthermore, in one or more embodiments, the quantity and spacing of generators 1 around the rim 7 is such that the number of generators 1 experiencing a normal force due to tire compression at any given momentduring tire rotation can be any suitable number. For example, for simplicity, the above passages describe an embodiment in which three generators 1-a, 1-b and 1-c experience the normal force from the road at a given moment. However, in other embodiments, this number can be another number, e.g. five or six generators 1.

[0118] Furthermore, Figure 1(c) shows the coil 16 (i.e. the second component) of the linear inductive generator 1 embedded in, and / or mounted within a recess or housing 72 of, the rim 7 of the wheel. In this manner, the coil 16 is in thermal contact with the rim 7, thereby allowing the rim 7 to act as a heat sink, which can improve the thermal management of the energy harvesting system 100. In one or more embodiments, coil 16 is configured to remain substantially stationary relative to the linear movement of the plunger 14. In other words, there is negligible movement of the coil 16 apart from the coil 16 rotating integrally with the rim 7. Coil 16 may have an annular or tubular shape, as shown in Figure 7.

[0119] Thus, the above-described energy harvesting system 100 and assemblies 100-a and 200 provide an arrangement of one or more linear inductive generators 1 with corresponding position sensors 9 which can be embedded in a wheel of a vehicle.

[0120] This arrangement provides several advantageous applications. For example, this arrangement can enable selective or smart energy harvesting based on the state of tire deformation (compression or decompression) and the stroke of the plunger as well as based on one or more vehicle driving conditions. Furthermore, the sensor 9 can detect tire deflation and can activate safety features in the energy harvesting system 100 to facilitate troubleshooting, maintenance and repair of the tire and / or wheel.

[0121] A further use of the sensor 9 is to gather tire deformation data corresponding to movement of the magnet 15. This may be used to analyze and / or predict a tire’s requirement for maintenance and / or replacement. For example, sensor data can be received by the control unit 80 and transmitted to the vehicle ECU and / or external processing and / or computing device. An algorithm can be used to detect, based on parameters such as vehicle and model information and historical data of the vehicle and tire use, to determine whether the tire needs to be replaced or serviced. Advantageously, such a method can be used for early detection of flat tires.

[0122] Data collected by the sensor 9 can further be used to tune or adjust the behaviour of other electrical or electromechanical components of a vehicle. For example, sensor data can be analyzed to control the functionality of other motion actuators and suspension actuators for increased safety and ride comfort. Sensor data also can provide equivalent tire pressure data to a vehicle and can thereby eliminate the need of installing a dedicated tire pressure monitoring system (TPMS) in modern vehicles.

[0123] Smart Energy Harvesting

[0124] In preferred embodiments, the energy harvesting system 100 implements selective (‘smart’) harnessing of energy, which will now be described. As previously mentioned, the system 100 preferably comprises a positionsensor 9 configured to detect a change in position of the magnet 15 and generate an output signal to be received and processed by the control unit 80. Control unit 80 can then process the output signal of the sensor 9 of the energy harvesting system 100, and optionally, process one or more driving condition signals received from the vehicle ECU, to determine whether or not to extract electrical energy from the linear inductive generator 1. As discussed in detail below, the (change in) position of the magnet 15 detected by the position sensor 9 provides information for the control unit 80 to determine whether the tire is being compressed or decompressed.

[0125] In more detail, the control unit 80 is further configured to determine, based on a first output signal of the sensor 9, that the deformation of the corresponding portion of the tire corresponds to a decompression of the portion of the tire. For example, the sensor 9 detects a change in position of the magnet 15 corresponding to a downstroke of the plunger 14, as discussed above, and sends a corresponding first output signal to the control unit 80.

[0126] In response to the first output signal, control unit 80 activates an output circuit of the linear inductive generator 1 during decompression of the portion of the tire, thereby enabling energy harvesting. For example, control unit 80 adjusts a circuit component, state or property of the output circuit to enable energy harvesting. In a nonlimiting example, a changeable state or property may comprise (the equivalent of) changing the output circuit, which includes the coil, from an open circuit to a closed circuit configuration, e.g. by changing a load resistance, to thereby enable current flow and energy extraction.

[0127] Similarly, control unit 80 is further configured to determine, based on a second output signal of the sensor 9, that the deformation corresponds to a compression of the portion of the tire. For example, the sensor 9 detects a change in position of the magnet 15 corresponding to an upstroke of the plunger 14, as discussed above, and sends a corresponding second output signal to the control unit 80.

[0128] In response to the second output signal, control unit 80 deactivates the output circuit of the linear inductive generator 1 during compression of the portion of the tire, thereby limiting energy harvesting. For example, control unit 80 adjusts a circuit component, state or property of the output circuit to limit or prevent energy harvesting. In a non-limiting example, a changeable state or property may comprise (the equivalent of) changing from a closed circuit to an open circuit configuration, e.g. by changing a load resistance to an effective infinite load resistance, inhibiting current flow.

[0129] Furthermore, in response to the second output signal, control unit 80 can also activate the output circuit of the linear inductive generator 1. For example, control unit 80 can process one or more driving condition signals received from the vehicle to determine whether to activate or deactivate the output circuit during the plunger 14 upstroke. As described herein, activation of the output circuit also refers to maintaining an activated state of the output circuit (i.e. enabling current flow to enable energy extraction). Similarly, deactivation of the output circuit also refers to maintaining a deactivated state of the output circuit.As discussed in more detail below, control unit 80 is configured to communicate with an electronic control unit (ECU) of a vehicle and receive one or more driving condition signals from the ECU. A non-exhaustive list of such driving condition signals include, but are not limited to: deceleration of the vehicle, braking of the vehicle, application of drive to a, or the, wheel of the vehicle; and / or vehicle inclination (i.e. the vehicle traveling on an uphill or downhill slope). In response to the one or more driving condition signals, control unit 80 controls (i.e. activates or deactivates) the output circuit of the linear inductive generator 1 accordingly.

[0130] With reference to Figure 16 showing the flowchart 900, control unit 80 processes the driving condition signals to selectively enable energy harvesting. For example, as discussed above, the normal force distribution on a tire contact patch is typically shifted forwards (relative to the direction of travel) when the wheel (with a compressible, e.g. rubber-based, tire) is rotating which contributes to rolling resistance, as is known in the art. The generation of Lorentz forces during the upstroke of the linear inductive generator 1 may act to increase the shift and thereby increase the rolling resistance of the tire during tire compression. As a result, in various embodiments, it may be preferable, by default, to not generate electricity during the upstroke. Instead, energy is only harvested during the upstroke if certain driving conditions are met. For example, as shown in Figure 16, the output circuit of the linear inductive generator 1 may be activated during the upstroke (and downstroke) if no acceleration is being applied by the vehicle (e.g. the wheels are not being driven and a brake is applied), if the vehicle is traveling downhill, or if the vehicle is decelerating. In another example, energy may be selectively harvested during the compression upstroke when (i) the wheels are not being driven; (ii) the vehicle is decelerating; and / or the vehicle is travelling on a downhill slope. On the other hand, during tire decompression (i.e. during the downstroke), rolling resistance may remain unaffected or reduced. As such, the output circuit of the generator 1 may be activated regardless of the driving condition signals.

[0131] Thus, control unit 80 can selectively enable energy harvesting from one or more of the plurality of generators 1 at any given time. For example, in Figure 1(b), control unit can activate the output circuit of generator 1-c., and, optionally, if the vehicle is travelling downhill, generators 1-a and 1-b can also be enabled to produce electrical power. The remaining generators 1 in the neutral state are preferably not switched on.

[0132] With reference to Figure 1(d), there is further provided a method 300 of harvesting energy from a wheel of a vehicle using the linear inductive generator 1 .

[0133] The method 300 comprises, in a first step S310, determining, based on an output signal of a position sensor 9 configured to detect a change in position of the first component of the generator 1 relative to the second component of the generator 1 , that an activation condition for activating an output circuit of the linear inductive generator 1 is met. In a second step S320 of method 300, the output circuit of the linear inductive generator 1 is selectively activated, thereby enabling energy harvesting based on the determination of the activation condition.For example, an activation condition comprises a deformation (compression or deformation) of the tire of the wheel. Preferably, determining the activation condition comprises processing, by the control unit 80, the output signal of the position sensor 9 corresponding to a change in position of the first component to determine whetherthe change in position corresponds to decompression of the portion of the tire. Therefore, the activation condition of the generator 1 is determined based on the position of a movable component of the generator 1 to determine whetherthe tire is being compressed or being decompressed.

[0134] There is further provided a method of harvesting energy from a wheel of a vehicle using the linear inductive generator 1 comprising controlling an output circuit of the linear inductive generator 1 to control energy harvesting based on one or more driving condition signals received from an electronic control unit of the vehicle. Preferably, the one or more driving condition signals indicate one or more of deceleration of the vehicle, braking of the vehicle; application of drive to the wheel of the vehicle, and / or vehicle inclination. Furthermore, this method can be implemented in an energy harvesting system with or without a position sensor 9. In other words, a determination to enable energy harvesting based on one or more driving conditions can be made in conjunction with, or independently from, the activation conditions related to tire compression and decompression.

[0135] As discussed above, the energy harvesting system 100 thus selectively harnesses energy based on detection of the plunger stroke (corresponding to a compression or decompression stage of tire deformation) and / or based on one or more driving condition signals. Advantageously, the system 100 can thus minimize any additional rolling resistance caused by the generators 1 .

[0136] In more detail, as is known in the art, a moving wheel overcomes rolling resistance caused by tire hysteresis due to vehicle weight deforming the tire. Further contributions to rolling resistance are made in the energy harvesting system 100 due to (i) the additional weight of the generators 1 in the wheel and (ii) Lorentz forces acting to oppose the motion of the magnet 15 within the electromagnetic field of the coil 16.

[0137] During the compression stroke (i.e. the plunger upstroke), the magnet 15 is configured to move radially inwards towards the coil 16. When the generator 1 is switched on to harvest energy, the coil 16 is energized and the interaction of the magnet 15 with the electric field of the coil 16 produces a Lorentz force acting in an opposing, i.e. radially outward direction to the movement of the magnet 15. This Lorentz force can increase the rolling resistance of the tire and can cause a further forward shift of the resultant normal force due to hysteresis. Thus, the energy harvested by the generators 1 during compression may result in a decreased net energy gain (or a net energy loss) as the vehicle must overcome the additional rolling resistance.

[0138] In view of this phenomenon, it may be advantageous to limit energy harvesting during the compression stroke under regular driving conditions, thus decreasing the rolling resistance. On the other hand, as discussed above, energy harvesting can be enabled during the compression stroke under certain driving conditions. For example, there is a decreased (or none) burden on the vehicle to overcome the additional rolling resistance when thewheels are not being driven, the vehicle is not accelerating or is travelling downhill. In such instances, energy harvesting can be enabled without consuming the vehicle’s fuel and / or battery further due to additional rolling resistance.

[0139] During the decompression stroke, the magnet 15 moves radially outwards away from the coil 16, thus the opposing Lorentz force acts in a radially inwards direction and thus does not contribute any additional rolling resistance for the vehicle to overcome. Furthermore, rolling resistance due to hysteresis may be reduced due to the faster tire decompression resulting from the centrifugal force of the moving mass of the generators 1 acting on the tire contact patch. As a result, energy can be harvested during the plunger downstroke in all driving conditions (e.g. Wheels driven I not driven, Accelerating I Decelerating, Flat I uphill I downhill).

[0140] Tire Deflation Detection

[0141] Control unit 80 can further process the output signal of the position sensor 9 to determine whether the tire is partially or fully deflated. For example, control unit 80 is further configured to determine that the tire is at least partially deflated based on a third output signal meeting a threshold condition. Thus, the (change in) position of the magnet 15 detected by the position sensor 9 provides information for control unit 80 to determine whether the tire is at least partially or fully deflated. For example, the third output signal (different from the first and second output signals described above) can correspond to the magnet 15 occupying a position beyond the range of its initial extended position and peak retracted position (e.g. the range of positions of the generators 1 -n, 1-a, 1-b, 1-c and 1-m shown in Figure 1(b).

[0142] In more detail, when a tire begins to deflate, there is a decrease in the internal tire pressure. As a result, plunger 14 and magnet 15 may retract beyond a threshold position of deflation (i.e. beyond the position corresponding to the end of the upstroke shown in generator 1-c). This movement is detected by the position sensor 9 which sends a corresponding third output signal to the control unit 80.

[0143] In response to receiving the third output signal which indicates that the tire is at least partially deflated, control unit 80 is configured to energize the linear inductive generator 1 to cause the first component (i.e. the plunger 14) to move towards the second component (i.e. the coil 16) and thereby retract the first component away from the tire in use. In this context, energizing means operating the coils as a solenoid, by applying current through the coil to induced a force on the magnet that causes the plunger to retract. For example, the generator 1 is energized to secure the magnet 15 inside the housing or recess 72 of the rim to limit the plunger 14 and magnet 15 from extending radially outwards.

[0144] In one or more embodiments, in response to receiving the third output signal from a subset (i.e. one or more) sensors 9, the control unit 80 energizes a subset or all of the linear inductive generators 1 to retract the plunger 14 of each of these generators 1 away from the tire. Thus, these components of the linear inductive generator1 are secured away from maintenance or repair sites that may need to be accessed, e.g. to replace or inflate the tire.

[0145] Additionally, after the plunger assembly is retracted in response to deflation detection, a spring-loaded locking pin (not shown) permanently holds each of the plunger assemblies in the retracted position. Thus, even after generator coils 16 are de-energized, the plunger assembly remains in its retracted position. The locking pin can be released manually, e.g. after maintenance work on a flat tire has been conducted by a service person.

[0146] Wireless Energy Transfer System

[0147] The energy transfer system 3 (shown in isolation in Figures 12(a), 12(b) and 13) of the energy harvesting system 100 will now be described. Specifically, an arrangement of features which are configured to transfer the harvested / recovered energy from the linear inductive generators 1 to the vehicle is described below. It will be understood that the energy transfer system 3 can be provided with or without the position sensor 9.

[0148] With reference to Figures 3(a), 3(b), 8, 9 and 10, the energy harvesting system 100 further comprises a wireless power transmitter 32 and a wireless power receiver 33. The transmitter 32 is connectable to an output circuit of the linear inductive generator 1 for receiving and transmitting energy harvested by the generator 1. The receiver 33 is connectable to a part of a vehicle body, for example a brake caliper 35 of the wheel, for receiving energy transmitted from the wireless transmitter 32.

[0149] In more detail, as shown in Figure 3(a), the energy transfer system 3 is embedded in the wheel of the vehicle, for example adjacent or proximate (i.e. located on one side of) the rim 7. Specifically, the energy transfer system 3 is located between the rim 7 and a brake caliper 35 of the wheel, such that at least a portion of the system 3, e.g. the receiver 33, is mounted on the brake caliper 35.

[0150] The energy transfer system 3 further comprises an electronics hardware assembly 31 for the transmitter 32 and an electronics hardware assembly 34 for the receiver 33. System 3 may also optionally include the brake caliper 35. As shown in Figure 3(a), the transmitter 32, receiver 33 and electronics assemblies 31 and 34 have a substantially annular shape similar to the shape of the rim 7. Transmitter 32 and receiver 33 are implemented as coils. The electronics assemblies 31 and 34 may comprise one or more printed circuit boards comprising power electronics required for transmitter coil 32 and receiver coil 33 respectively. Accordingly, transmitter coil 32 and receiver coil 33 may comprise one or more printed circuit boards for routing signals and to provide connection to the respective transmitter hardware 31 or receiver hardware 34.

[0151] The components of the system 3 extend axially from the rim 7 to the brake caliper 35, as shown in the exploded view of Figure 10. Specifically, the transmitter electronics assembly 31 is arranged next to or inside the rim 7 for electrical and / or wireless contact with the output circuit of the plurality of generators 1 located circumferentially around the rim 7. As discussed above, control unit 80 can be embedded within the assembly31. The wireless transmitter 32 is attached between the assembly 31 and a first side of the receiver 33 on the wheel. The receiver electronics assembly 34 is attached to an opposing, second side of the receiver 33, and as shown in Figure 9, the brake caliper 35 is mounted onto the receiver 33 and assembly 34.

[0152] When the generator 1 is actuated (i.e. when the magnet 15 moves relative to coil 16) and the output circuit is activated, the output circuit of the generator 1 energizes the electronics assembly 31 , thereby transferring the inductive electrical powerto the assembly 31. The wireless transmitter 32 then converts the received harvested energy into a high-frequency signal before transmitting said high-frequency signal to the wireless receiver 33.

[0153] In this manner, the harvested energy from the generators can be wirelessly transferred to the receiver 33, thus avoiding the need for wired energy transfer in the wheel.

[0154] The wireless receiver 33 is electrically connectable, preferably via the wireless receiver’s electronics hardware assembly 34, to a vehicle power circuit to supply said harvested energy to the vehicle. For example, with reference to Figure 3(a), a wire 4 protruding through the caliper 35 connects the receiver 33 and electronics assembly 34 with voltage converter unit (e.g. DC-to-DC converter 5) for converting said harvested energy (which is in the form of a low-voltage direct current) to a matching voltage of the vehicle. For example, the converter 5 converts the received energy to a high-voltage or low-voltage direct current or any other voltage level to match the vehicle battery’s operating voltage.

[0155] The wireless receiver 33 is further electrically connectable, via wires 6, and preferably via the DC-to-DC converter 5, to a high-voltage power distribution unit (shown in Figure 14) of the vehicle for supplying said harvested (or received) energy to a motor unit of the vehicle.

[0156] With reference to Figure 3(c), there is further provided a method 500 of harvesting energy from a wheel of a vehicle using the linear inductive generator 1. The method 500 comprises, in a first step S510, activating an output circuit of the linear inductive generator 1 to enable energy harvesting. A second step S520 of the method 500 comprises wirelessly transmitting, using a wireless transmitter 32, preferably using a wireless transmitter assembly comprising the transmitter electronics hardware assembly 31 and transmitter coil 32, the harvested energy from the output circuit of the linear inductive generator 1 to a wireless receiver 33, preferably to a wireless receiver assembly comprising the receiver coil 33 and receiver electronics hardware assembly 34, for supplying the energy to the vehicle. The wireless receiver 33 (e.g. the wireless receiver coil 33) is located proximate the wireless transmitter 32 (e.g. the wireless transmitter coil 32). For example, the receiver 33, and preferably the wireless receiver assembly comprising the receiver coil 33 and receiver electronics hardware assembly 34, is located on a brake caliper 35 of the wheel.

[0157] Optionally, the method 500 further comprises, in a step S530, transmitting said harvested energy from the wireless receiver 33, and preferably from the wireless receiver assembly comprising the receiver coil 33 and receiver electronics hardware assembly 34, to an electric / electronic circuit component for use by the vehicle,preferably wherein the electronic circuit component is configured to match an output voltage of the harvested energy to a voltage of a battery of the vehicle.

[0158] Referring again to figures 1 to 16, an energy harvesting system using tire deformation according to an embodiment of the present invention may include linear electricity generation mechanism 1 that converts compression and decompression of a tire 2 into electricity. The tire 2 gets compressed due to the weight of the vehicle and decompressed when tire 2 rotates due to tire pressure inside the tire 2 pushes out the wall of the tire 2. Generated electricity is wirelessly transferred to an electric vehicle (EV) using a wireless transfer mechanism 3 that is integrated into the brake caliper 35 for mechanical support. A wire 4 is used to conduct energy received by wireless energy transfer system 3 to DC-to-DC converter 5 that converts the voltage levels of wirelessly received electrical energy to required voltage levels of a high voltage traction battery in the vehicle. This high voltage electrical energy is then fed to a high voltage distribution unit in the vehicle using high voltage positive and negative wires 6. The high voltage distribution unit in the vehicle is connected to a traction motor I inverter for propulsion of vehicle. In this way, harvested energy is used in real time for propulsion purposes instead of storing it.

[0159] Compression force on tire: Vehicle weight is distributed to each wheel of the vehicle. This weight causes normal force on each wheel due to gravity. Due to this force, the tire gets compressed and creates a contact patch area where tire 2 and road surface touches. This contact patch is important for the traction and stability of the vehicle. The force causing such tire compression is henceforth called a compression force (Fc). Some percentage of the compression force can be consumed by energy harvesting system.

[0160] Decompression force on tire 2: When the tire 2 rotates, the contact patch area formed due to compression force moves away from road surface. Due to air pressure in tire 2 and centrifugal force, the contact patch returns to its normal shape. It is important that the contact patch returns to its normal shape, that is the normal round shape of tire 2 (e.g. if it is not returned to its normal shape, it may cause vehicle stability issues). The force causing tire decompression is henceforth called a decompression force (Fd). Some percentage of compression force can be consumed by energy harvesting system.

[0161] Linear electricity generator: The linear electricity generator 1 converts linear motion of a magnet 15 and plunger 14 to electricity by the principle of induction of current in coil 16 (e.g. a copper coil). This linear motion of the plunger is due to compression and decompression force acting on tire inner surface.

[0162] The pad 11 is made of durable light weight material. It is designed to interface with the inner surface of tire 2 for uniform distribution of forces on tire. Pad 11 is further interfaced with plunger 14 with the help of a ball joint. A ball joint helps the pad 11 to remain in contact with the inner surface of the tire even when road surface is not even and tire surface is deformed unevenly. Ball joint is preferably formed by socket 13 attached to pad 11 and a ball 13 on the plunger 14. The pad 11 has a width and a length. The length is in the circumferential direction of the wheel, and the width is in a perpendicular direction, e.g. an axial direction. The width ispreferably substantially greater than the length, as shown, to distribute the forces across the tire width. The width may be configured, in use, to extend across, or substantially match, the width of the tire contact patch with a driving surface.

[0163] The compression force and decompression forces (Fc, Fd) are transferred to the plunger 14. The plunger 14 causes the magnet 15 to move in to the coil 16 during the compression cycle and move out of the coil 16 during the decompression cycle. This linear motion of magnet 15 inside the coil 16 induces voltage and current in the coil. This induced electric current is provided to wireless energy transfer mechanism 3.

[0164] Wireless energy transfer mechanism: Wireless energy transfer mechanism 3 is used to transfer harvested electrical energy to the vehicle. The wireless energy transfer mechanism 3 consists of two coils, a transmitter coil 32 and a receiver coil 33. They work on the principle of electromagnetic induction. Transmitter coil’s electronic hardware 31 receives electrical energy from linear electricity generator 1 and converts it to a high frequency signal, which is fed to the transmitter coil 32. This high frequency signal causes electromagnetic induction in the receiver coil 33. The receiver coil 33 provides received electrical energy to the receiver coil’s electronics hardware 34, which converts the received energy to a direct current (DC), e.g. providing a low voltage direct current (LVDC) power supply. This LVDC voltage can be 12V or 24V or 48 V depending on design requirements. This LVDC voltage is preferably further provided to DC-to-DC converter 5 (e.g. through a wire 4 which may be copper or aluminum). The electronics used in the wireless energy transfer system is preferably ISO 26262 compliant. The receiver coil 33 and its electronics hardware 34 is preferably integrated to the brake caliper 35 mechanism to provide mechanical support. The caliper 35 also helps to maintain a constant and small air gap between the transmitter coil 32 and receiver coil 33.

[0165] DC-to-DC converter: The DC-to-DC converter 5 will be referred to as DCDC 5 henceforth. DCDC 5 receives the LVDC electrical energy from the wireless energy transfer system 3 (of all the tires). DCDC 5 converts LVDC electrical energy to a high voltage direct current (HVDC). The voltage level of the HVDC output from DCDC 5 is preferably matched with a HVDC voltage from a HV traction battery in the vehicle. This HVDC electrical energy is provided to a vehicle (through high voltage wires 6) for using it for propulsion system. Electric vehicles typically include a high voltage power distribution unit (HVPDU). The HVDC electrical energy from DCDC 5 is preferably interfaced with HVPDU. In this way, it is made available for the vehicle. As this system supplements the HV battery in the electric vehicle, it results in a range boost.

[0166] The system and methods disclosed herein can be applied to electric vehicles (EVs) to extend driving range; hybrid vehicles to supplement battery charging; and fleet vehicles to improve energy efficiency.

[0167] Reference Signs List: 1 - Linear electricity generator ; 11 - Pad; 12 - Ball socket; 13 - Ball on the plunger; 14 - Plunger; 15 - Magnet; 16 - Coils; 2 - Tire; 3 - Wireless energy transfer system; 31 - Electronics Hardware for transmitter coil; 32 - Transmitter coil; 33 - Receiver coil; 34 - Electronics Hardware for receiver coil; 35 -Brake caliper; 4 - Wire between Wireless energy transfer system and DC-to-DC converter; 5 - DC-to-DC converter; 6- High voltage wires for conducting high voltage energy to vehicle; 7 - Rim of the wheel.

[0168] A further specific example illustrating the advantages of embodiments disclosed herein is provided, with reference to Tables 1 - 3 below. Specifically, the effect of implementing the energy harvesting system 100 and smart energy harvesting was calculated for two vehicles having the specifications shown in Table 1 below.

[0169] & &

[0170]

[0171] Table 1 : Vehicle Parameters

[0172] As shown in Table 2, a range boost of 21% was calculated for Vehicle 1 and a range boost of 7% was expected for Vehicle 2. The range boost takes into account the additional weight of the energy harvesting system which puts an additional power demand on the vehicle propulsion system. Thus, the “useful” energy generated by the energy harvesting system is calculated as the balance of the generated electricity and the power loss due to the weight of the energy harvesting system.

[0173]

[0174]

[0175] Table 2: Energy Demand

[0176] Table 3 shows the calculated numbers for range boost of Vehicle 1 and 2 which take into account power loss due to rolling resistance. A range boost of 18.18% was achieved for Vehicle 1 and 5.82% for vehicle 2. Furthermore, the implemented smart energy harvesting mechanism was restricted to energy harvesting during downstroke. Thus, a greater overall energy net gain than the below numbers is expected if the experiments are rerun with event-based energy harvesting during the upstroke (i.e. based on driving condition signals) enabled.

[0177]

[0178] Table 3: Consolidated energy balance and range boost (60 mph)

[0179] It will be understood that the present invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention. Each feature disclosed in the description, and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination.Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalization thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention. Reference numerals appearing in the claims are by way of illustration only and shall have no limiting effect on the scope of the claims.

Claims

CLAIMS1. An energy harvesting system for a wheel of a vehicle, the energy harvesting system comprising:a linear inductive generator configured to extend substantially radially, in use, between a rim of the wheel and a portion of a tire mountable around the rim, the linear inductive generator comprising a first and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy; anda position sensor configured to detect a change in position of the first component relative to the second component for use in controlling the energy harvesting system.

2. The energy harvesting system of claim 1 , further comprising a control unit configured to receive an output signal from the position sensor corresponding to a change in position of the first component; and preferably, wherein the position sensor comprises a magnetic sensor device.

3. The energy harvesting system of claim 2, wherein the control unit is further configured to selectively activate an output circuit of the linear inductive generator to enable energy harvesting based on the received output signal.

4. The energy harvesting system of claim 2 or 3, wherein the control unit is further configured to:determine, based on the output signal, that the deformation corresponds to a decompression of the portion of the tire; andactivate an output circuit of the linear inductive generator during decompression of the portion of the tire to enable energy harvesting, preferably wherein:activating the output circuit of the linear inductive generator comprises adjusting a circuit component, state or property of the output circuit to enable energy harvesting.

5. The energy harvesting system of any of claims 2 to 4, wherein the control unit is further configured to: determine, based on the output signal, that the deformation corresponds to a compression of the portion of the tire; anddeactivate an output circuit of the linear inductive generator during compression of the portion of the tire to limit energy harvesting, preferably wherein:deactivating the output circuit of the linear inductive generator comprises adjusting a circuit component, state or property of the output circuit to limit or prevent energy harvesting.

6. The energy harvesting system of any of claims 2 to 5, wherein the control unit is configured to:communicate with an electronic control unit of a vehicle;receive one or more driving condition signals from the electronic control unit; andcontrol an output circuit of the linear inductive generator based on the one or more driving condition signals, preferably wherein the one or more driving condition signals indicate one or more of:deceleration of the vehicle;braking of the vehicle;application of drive to a, or the, wheel of the vehicle; and / orvehicle inclination.

7. The energy harvesting system of any of the preceding claims, wherein:the second component comprises a coil mountable to or in the rim of the wheel; andthe first component comprises a plunger configured to extend from the second component to the portion of the tire, the plunger comprising one or more magnets at an end proximate the second component.

8. The energy harvesting system of any of the preceding claims, wherein the linear inductive generator comprises a pad coupled to an end of the first component proximate the portion of the tire in use, the pad configured to releasably contact an inner surface of the portion of the tire.

9. An energy harvesting system for a wheel of a vehicle, the energy harvesting system comprising:a linear inductive generator configured to extend substantially radially, in use, between a rim of the wheel and a portion of a tire mountable around the rim, the linear inductive generator comprising a first and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy; andwherein the linear inductive generator comprises a pad coupled to an end of the first component proximate the portion of the tire in use, the pad configured to releasably contact an inner surface of the portion of the tire.

10. The energy harvesting system of claim 8 or 9, wherein the pad is rotatably coupled to the end of the first component, preferably via a ball joint arrangement.

11. The energy harvesting system of any of claims 2 to 10, wherein the control unit is further configured to determine, based on the output signal from the position sensor, that the tire is at least partially deflated.

12. The energy harvesting system of claim 11 , wherein the control unit is further configured to determine that the tire is at least partially deflated based on the output signal meeting a threshold condition.

13. The energy harvesting system of claim 11 or 12, wherein, in response to determining that the tire is at least partially deflated, the control unit is configured to energize the linear inductive generator to cause the first component to move towards the second component and thereby retract the first component away from the tire in use.

14. The energy harvesting system of any preceding claim, further comprising:a wireless transmitter connectable to an output circuit of the linear inductive generator for receiving and transmitting energy harvested therefrom; anda wireless receiver connectable to a part of a vehicle body, preferably connectable to a brake caliper of the wheel, for receiving energy transmitted from the wireless transmitter.

15. An energy harvesting system for a wheel of a vehicle, the energy harvesting system comprising:a linear inductive generator configured to extend substantially radially, in use, between a rim of the wheel and a portion of a tire mountable around the rim, the linear inductive generator comprising a first and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy;a wireless transmitter connectable to an output circuit of the linear inductive generator for receiving and transmitting energy harvested therefrom; anda wireless receiver connectable to a part of a vehicle body, preferably connectable to a brake caliper of the wheel, for receiving said energy transmitted from the wireless transmitter.

16. The energy harvesting system of claim 14 or 15, wherein one or more of:the wireless receiver is electrically connectable to a vehicle power circuit to supply said harvested energy to the vehicle;the wireless receiver is electrically connectable to a high-voltage power distribution unit of the vehicle for supplying said harvested energy to a motor unit of the vehicle;the wireless receiver comprises or is electrically connectable to a voltage converter unit for converting said harvested energy to a high-voltage or low-voltage direct current;the wireless receiver is electrically connectable to a voltage converter unit of the vehicle for matching a voltage level of said harvested energy to a voltage level of a battery of the vehicle;in use, the wireless transmitter is configured to be attached to the wheel; and / orthe wireless transmitter is configured to convert the received harvested energy into a high-frequency signal before transmitting said high-frequency signal to the wireless receiver.

17. A wheel assembly, comprising:a wheel for a vehicle; andan energy harvesting system according to any of the preceding claims, wherein the linear inductive generator extends substantially radially from a rim of the wheel; and preferably,wherein the wheel assembly further comprises the tire mounted around the wheel, and the linear inductive generator extends between the rim and a portion of the tire.

18. The wheel assembly of claim 16, further comprising a plurality of said linear inductive generators distributed circumferentially around the rim; and preferably,wherein the plurality of linear inductive generators comprises at least 20 linear inductive generators, more preferably at least 25 linear inductive generators, further preferably at least 30 linear inductive generators.

19. The wheel assembly of claim 16 or 17, wherein the second component comprises a coil and is embedded in, and / or mounted within a recess of, the rim of the wheel, such that the coil is in thermal contact with the rim.

20. A wheel assembly, comprising:a wheel for a vehicle; andan energy harvesting system for integration with the wheel, wherein the energy harvesting system comprises:a linear inductive generator configured to extend substantially radially, in use, between a rim of the wheel and a portion of a tire mountable around the rim, the linear inductive generator comprising a first and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy; and wherein the second component comprises a coil and is embedded in, and / or mounted within a recess of, the rim of the wheel, such that the coil is in thermal contact with the rim.

21. A vehicle comprising the energy harvesting system of any of claims 1 to 16 and / or comprising the wheel assembly of any of claims 17 to 20.

22. The vehicle of claim 21 , wherein the energy harvesting system comprises a control unit in communication with an electronic control unit of the vehicle, the control unit configured to control an output circuit of the linear inductive generator based on one or more driving condition signals received from the electronic control unit of the vehicle, preferably wherein the one or more driving condition signals indicate one or more of:deceleration of the vehicle;braking of the vehicle;application of drive to a, or the, wheel of the vehicle; and / orvehicle inclination.

23. A method of harvesting energy from a wheel of a vehicle using a linear inductive generator, the linear inductive generator extending substantially radially between the rim of the wheel and a portion of a tire mounted on the rim, the linear inductive generator comprising a first and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy, the method comprising:determining, based on an output signal of a position sensor configured to detect a change in position of the first component relative to the second component, that an activation condition for activating an output circuit of the linear inductive generator is met; andselectively activating the output circuit of the linear inductive generator to enable energy harvesting based on the determination, preferably wherein determining the activation condition comprises:processing, by a control unit, the output signal of the position sensor corresponding to a change in position of the first component to determine whether the change in position corresponds to decompression of the portion of the tire.

24. A method of harvesting energy from a wheel of a vehicle using a linear inductive generator, the linear inductive generator extending substantially radially between the rim of the wheel and a portion of a tire mounted on the rim, the linear inductive generator comprising a first and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy, the method comprising:activating an output circuit of the linear inductive generator to enable energy harvesting; and transmitting, using a wireless transmitter, the harvested energy from the output circuit of the linear inductive generator to a wireless receiver located proximate the wireless transmitter, preferably located on a brake caliper of the wheel, for supplying to the vehicle; and preferablytransmitting said harvested energy from the wireless receiver to an electronic circuit component for use by the vehicle, preferably wherein the electronic circuit component is configured to match an output voltage of the harvested energy to a voltage of a battery of the vehicle.

25. A method of harvesting energy from a wheel of a vehicle using a linear inductive generator, the linear inductive generator extending substantially radially between the rim of the wheel and a portion of a tire mounted on the rim, the linear inductive generator comprising a first and second component, wherein the first component is movable relative to the second component in response to deformation of the portion of the tire for harvesting energy, the method comprising:controlling an output circuit of the linear inductive generator to control energy harvesting based on one or more driving condition signals received from an electronic control unit of the vehicle, and preferably wherein the one or more driving condition signals indicate one or more of:deceleration of the vehicle;braking of the vehicle;application of drive to a, or the, wheel of the vehicle; and / orvehicle inclination.

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