A kinetic energy harvesting device

Abstract

A kinetic energy harvesting system for converting mechanical energy into electrical energy, comprises at least one pivotally mounted see-saw mechanism with a pair of displaceable platforms 4, 6, in wh

Description

The present invention relates to an energy harvesting system. More particularly, but not exclusively, the present invention relates to a system that converts kinetic energy, for example from passing traffic (vehicles) to generate a hydraulic flow which can be used to generate electricity or a provide mechanical advantage. Background As global energy demands grow, it is becoming increasingly important to reduce the negative impact on the environment and in particular to generate electricity without burning fossil fuels. With the escalating climate crisis, mounting pressure is being placed on businesses and governments to reduce carbon emissions. Most businesses and governments have committed to achieving net-zero emissions by 2050 or earlier. For many businesses, this involves electrifying their operations, which requires expanding connections to the grid and / or building on-site generation. However, there are several challenges with building sustainable on-site energy solutions that are currently available, typically wind and solar: • Cost and investment: Sustainable energy solutions require substantial upfront investments and lengthy periods to recover costs. • Space and planning: Solar generation requires extensive land and / or roof space, which is in scarce supply at many sites. The planning requirements for both solar and wind can be onerous and take time. • Volatility of energy generation: Solar and wind generation is weather dependent and can result in an extensive investment in batteries to ensure continuity of supply. • Carbon footprint: Manufacturing, installing, and maintaining sustainable energy generation can result in an additional carbon footprint, diminishing their overall effectiveness in achieving net zero targets Electricity generation systems and methods for converting energy exist. Conventional electricity generation systems, also referred to as energy harvesting systems, require a continuous passage of people or vehicles and generate electricity through the conversion of kinetic energy from mechanical forces and are often referred to as energy harvesting systems. Conventional electricity generation systems can have an adverse effect on a vehicle passing over the platform which is especially undesirable at speed. Many of the energy harvesting systems which generate electricity by depression of a platform which in turn creates pressurisation of a working fluid have been found to be relatively inefficient. Attempts have been made to optimise the energy extraction from the movement of a variety of different vehicles although this has been problematic as the mass of vehicles varies significantly from a small car to a fully loaded heavy goods vehicle (HGVs). There is therefore a need for an energy harvesting system which is capable of improved energy extraction from the movement of a wide range of vehicles across it. There is also a need for an energy harvesting system which is resilient and less prone to damage on exposure to repeated shock loads. There is also a need for an energy harvesting system which does not negatively impact the vehicle moving across it. Summary of the Invention According to a first aspect of the present invention there is provided a kinetic energy harvesting system for converting mechanical energy into electrical energy, in which the kinetic energy harvesting system is configured in use to extend between adjacent areas of a transport surface to provide a contact surface defining a pathway for a vehicle, and in which the system comprises: at least one see-saw mechanism configured in use to be pivotally mounted, in which the seesaw mechanism comprises: a pair of first and second displaceable platforms, in which each of the first and second displaceable platforms comprises a first end, an opposed second end, and an upper surface extending therebetween, in which the upper surface provides a contact surface defining a pathway for vehicle movement; and a rigid strut connecting the first end of the first platform at or adjacent to the first end of the second platform. in which each of the first and second displaceable platform is moveable between a loaded position when the upper surface thereof is contacted by a vehicle; and an unloaded position when the upper surface thereof is free from contact with a vehicle; a torque arm connected to the at least one see-saw mechanism, in which the torque arm is mounted on a rotatable shaft configured in use to be rotatable on movement of the first and / or second displaceable platforms between the loaded position and unloaded position; at least one piston moveable within a cylinder comprising a working fluid, in which the at least one piston is in communication with the torque arm such that rotational movement of the torque arm causes translation movement of the piston within the cylinder to pressurise the working fluid; and at least one accumulator in fluid communication with the at least one cylinder to receive and store pressurised respective working fluid therefrom; in which the piston(s) is configured in use to be moveable within the cylinder in a direction extending substantially perpendicular to the pathway defined by the displaceable portions. The piston(s) is preferably configured in use to be moveable within the cylinder(s) in a direction extending substantially perpendicular to the rotational axis of the rotatable shaft. The piston(s) is preferably configured in use to be moveable within the cylinder(s) in a direction extending substantially parallel to the direction of movement of the displaceable platforms. The longitudinal axis of the piston and respective cylinder preferably extends substantially parallel to the direction of movement of the displaceable platforms. By arranging the piston(s) and respective cylinder(s) in this way, the system is more efficient and more compact and less prone to damage during use. Furthermore, the system of the present invention enables the vehicle to move onto the see-saw mechanisms without encountering a "speedbump" effect leading to improved energy harvesting. This arrangement provides for the maximum return of power for the shortest stroke length of the piston. The torque arm is preferably arranged to extend substantially perpendicular to the longitudinal axis defined by the piston(s) / cylinder(s) (i.e. to the translation movement of the piston(s) within the respective cylinder(s)). This arrangement helps to provide for vertical transmission of the torque into the cylinder. This arrangement significantly helps to reduce sideloads being exerted onto the piston(s) thereby increasing cylinder life and mechanical efficiency. The longitudinal axis of the piston(s) / cylinder(s) preferably extends in a direction extending substantially perpendicular to the pathway defined by the displaceable portions. It has been found that the arrangement of the piston(s) / cylinder(s) in this manner results in a system which is at less risk of ingress of dirt and detritus into the piston(s) / cylinder(s) during use resulting in less risk of failure of the system. The arrangement of the piston(s) / cylinder(s) in this manner also allows for small translational movements of the piston(s) relative to the cylinder(s) which therefore reduces the risk of fatigue and failure of the system. By arranging the piston(s) / cylinder(s) as defined, the overall size of the area of the system is greatly reduced. This therefore means that the system is capable of providing a greater energy density during use. The torque arm is preferably in communication with a pair of pistons, each moveable within a respective cylinder comprising a working fluid. Within the or each pair of pistons, a first piston (and cylinder) is preferably located at or adjacent a first end of the torque arm, and a second piston (and cylinder) is preferably located at or adjacent a second end of the torque arm. The torque arm is preferably configured to be rotatable at or about a central portion located between a first and second opposed end thereof. The or each pair of displaceable platforms may be supported on any suitable number of torque arms. The number of torque arms present may be dependent on the end use of the system. The torque arm(s) is rotatable with rotational movement of the rotatable shaft. The rotatable shaft may be provided in a single piece or may be formed from multiple pieces engaged together depending on the end use. The system may comprise a plurality of see-saw mechanisms. The system may comprise a plurality of rotatable shafts, each shaft being in communication with at least one torque arm. The system may comprise a first see-saw mechanism mounted on a first torque arm which is mounted on a first rotatable shaft. The system may further comprise at least a second see-saw mechanism mounted on at least a second torque arm which is mounted on at least a second rotatable shaft. The first rotatable shaft, and first torque arm, are preferably arranged to be independently moveable with respect to the at least a second rotatable shaft and at least a second torque arm. One or more, preferably each, rotatable shaft and respective torque arm(s) is independently moveable (i.e. rotatable) on movement of the displaceable platform(s) of the respective see-saw mechanism. As such, each torque arm mounted on a rotatable shaft may be operable independently of other torque arms mounted on other rotatable shafts within the system. Each rotatable shaft may comprise any suitable number of torque arms mounted thereon. The system may therefore provide any suitable arrangement comprising any suitable number of see-saw mechanisms, rotatable shafts and torque arms depending on the requirements of the system. The system of the present invention may therefore be suitable for use with a variety of vehicles, including large twin wheeled axle vehicles. The pathway preferably provides a continuous neutral line level which is substantially flat as the tyre of a vehicle traverses from the transport surface along the system. As a result, the vehicle is not displaced upwardly or downwardly as the vehicle passes along the pathway. As such, the energy efficiency of the system is improved whilst minimising disruption, or risk of potential damage, to the vehicle. The contact surface of the displaceable platforms may be planar. The piston(s) / cylinder(s) may be located (and spaced away from) a side portion of the displaceable platforms to ensure that the piston(s) / cylinder(s) do not interfere with movement of the platforms during use. The system preferably comprises a self-priming single acting cylinder arrangement comprising the at least one piston and cylinder. The cylinders within the self-priming single acting cylinder arrangement are each preferably configured to receive working fluid from and to provide working fluid to the accumulator. Each cylinder is preferably a single acting cylinder. The system may comprise a plurality of see-saw mechanisms. The see-saw mechanisms may be configured to extend substantially parallel to each other so as to define a continuous pathway extending across all of the see-saw mechanisms. Preferably, the rotational axis of the rotatable shaft (s) and torque arm(s) extend substantially perpendicular to the direction of travel of the vehicle (or to the defined pathway). The contact angle between a tyre and a corresponding point on the substantially contact surface of the upper surface of the first or second displaceable portions (as the vehicle traverses the pathway) preferably remains constant, preferably 90 degrees. The pathway is defined as being the point of contact of the tyre with the upper contact surface of the displaceable portion(s) as the vehicle displaces across the system. The pathway, at the point of contact of the tyre as the vehicle moves across the first and second displaceable platforms, preferably provides a continuous neutral line which is substantially flat, and aligned with adjacent portions of the transport surfaces. The first and second displaceable portions (for example the first and / or second ends thereof) are preferably configured such that on contact with a rotating tyre approaching the displaceable portion (from for example the transport surface), the rotation of the tyre provides a driving force to move the displaceable portion in a downward direction to provide the upper surface thereof at a continuous neutral line level. For example, an end of the displaceable portion adjacent the transport surface is contoured to frictionally engage a rotating tyre to effect downward movement of the displaceable portion. The first and second displaceable portions (for example the first and / or second ends thereof) are preferably configured such that on contact with a rotating tyre, the rotation of the tyre provides a driving force to move the displaceable portion in a downward direction. The end of the displaceable portion adjacent the transport surface is preferably curved to aid contact with a rotating tyre to move the displaceable portion in a downward direction. The displaceable portion is preferably tapered inwardly from the first end towards the second end thereof. The displaceable portion is preferably wedge shaped. The kinetic energy harvesting system preferably comprises a pivot for rotatably mounting the see-saw mechanism. Each displaceable platform is preferably moveable between: an unloaded position in which the contact surface of the first or second displaceable platform extends above a neutral line level configured in use to be substantially aligned with an adjacent transport surface; and a loaded position in which the contact surface of the first or second displaceable platform is in contact with and depressed by loading caused by movement of a vehicle onto and / or along the contact surface of the first or second displaceable platform causing the contact surface to be positioned lower than in the unloaded position, such that the contact surface is aligned with the neutral line level. The kinetic energy harvesting system may further comprise: a hydraulic motor in communication with the accumulator(s) such that the stored pressurised working fluid drives the hydraulic motor; and an alternator configured in use to receive power from the hydraulic motor. Movement of a vehicle across the system of the present invention preferably occurs over two cycles: during a first cycle, the vehicle (in particular a tyre of the vehicle) contacts and moves across the contact surface of the first displaceable platform to move the platform from the respective unloaded position to the loaded position; and during a subsequent second cycle, the vehicle (in particular a tyre of the vehicle) contacts and moves across the contact surface of the second displaceable platform to move the platform from the unloaded position to the loaded position (causing the first displaceable platform to be moved to the unloaded position). Movement of the vehicle across the system may further include an initial cycle in which the tyre makes initial contact with a first end of the platform, and on rotation of the tyre, frictional engagement causes the platform to be displaced in a downward direction to align the contact surface with the neutral line level. The system is preferably configured (and in particular the first and second displaceable platforms are preferably configured) such that a tyre of a vehicle traverses the contact surfaces of the first and second displaceable platforms (for example see-saw mechanism) within a single turn of the tyre. In one embodiment, the system is configured (and in particular the first and second displaceable platforms are preferably configured) such that one of the first or second displaceable platforms is contacted with a tyre of a vehicle during a first half turn of the tyre, and such that the other of the second or first displaceable platform is contacted with the tyre of the vehicle during a subsequent second half turn of the tyre. The term "neutral line level" is used herein to refer to the level of the contact surface of the platforms when free from contact with a tyre of a vehicle. The "neutral line level" is preferably selected or adapted to be positioned adjacent and aligned with the adjacent transport surface adjacent the respective contact surface to provide for a smooth transitional pathway between the transport surface and the contact surface. References to a contact surface being substantially aligned with a neutral line level refer to the contact surface being aligned with minimal alteration in height with the adjacent transport surface. In one embodiment, the energy harvesting system is configured in use to be deployed within a roadway (for example within a trench provided within a roadway), or adjacent ramps positioned on or off-road, to provide a smooth transitional pathway from the transport surface (for example a roadway or ramps) across the contact surface of the kinetic energy harvesting system (for example without interruption in height of the vehicle during passage from the road or ramp onto the kinetic energy harvesting system). The first and second displaceable platforms each have a first end, a second opposed end, an upper surface defining a contact surface extending therebetween. Each platform preferably further comprises a pair of spaced apart side portions extending between the respective first and second ends thereof. The first and second displaceable platforms are preferably connected to each other such that the upper contact surfaces of each platform together form a V-shaped profile (when viewed from a side portion thereof). The first and second displaceable platforms (for example of the see-saw mechanism) are preferably arranged to define a longitudinal axis extending substantially perpendicular to the direction of travel of the vehicle (i.e. along the pathway). The first and second displaceable platforms (for example of the see-saw mechanism) are preferably arranged to define a longitudinal axis extending substantially parallel to the first ends of the platforms and / or the crank. The first end of a first displaceable platform preferably extends substantially parallel to (at or adjacent or spaced apart from) a first end of a second displaceable platform. The second ends of the first and second displaceable platforms are preferably located at a height above the first ends thereof, thereby defining a V-shaped profile (when viewed from a side portion thereof). The upper surface preferably has a substantially rectangular or square shape. The displaceable platforms preferably have a substantially rectangular or square cross-section. The displaceable platforms preferably have a substantially triangular transverse cross-section (extending substantially perpendicular to the longitudinal axis defined by the platforms). The system has been found to efficiently extract more energy from the movement of vehicles across the contact surface compared to conventional kinetic energy harvesting systems as a result of the use of two connected displaceable platforms. The kinetic energy harvesting system may further comprise a vehicle recognition system configured in use to detect a characteristic of a vehicle (for example an oncoming vehicle) and vary the resistance of movement of the at least one piston within the respective cylinder in order to optimise energy extraction. The vehicle recognition system may be configured in use to detect one or more characteristics of the oncoming vehicle. The one or more characteristics are preferably selected from one or more of: mass; dimension(s); Company operating the vehicle; Registration plate; or any combination thereof. In some embodiments the vehicle recognition system is configured in use to determine the mass of the oncoming vehicle using a sensor. The vehicle recognition system may comprise an imaging system configured in use to determine one or more dimensions of the oncoming vehicle. In some embodiments the vehicle recognition system comprises an automatic number plate recognition (ANPR) system. The resistance to movement of a piston within a respective cylinder may be set for exposure to a predetermined force, for example by the force exerted on transition of a heavy goods vehicle (HGV) across the contact surfaces of the platforms. As such, the same resistance may not be appropriate for a vehicle of less mass, such as a car or smaller truck. The system is preferably adaptable for improved energy harvesting efficiency when used by a variety of different vehicles. The viscosity of the working fluid(s) may be varied in order to adjust the resistance to movement of the piston within the respective cylinder. The viscosity of the working fluid(s) may be varied in order to adjust the resistance to movement of the piston within the respective cylinder in dependence on one or more detected characteristics (for example mass) of the oncoming vehicle. The viscosity of the working fluid(s) may be varied such that the working fluid provides for increased resistance to movement of a piston in respective cylinder when a heavier vehicle is transitioning across the contact surfaces of the displaceable platforms in comparison to the working fluid providing for reduced resistance to movement of the piston in respective cylinder when a lighter vehicle transitions across the contact surfaces. Such an arrangement not only improves efficiency of energy harvesting but may also reduce damage to the system providing for increased longevity and longer timespans between maintenance events. The system may further comprise a variable throttle in communication with the or each respective cylinder such that the throttle is operative to vary the resistance of movement of the piston within the respective cylinder. Preferably, the system comprises a variable throttle configured in use to control the flow of working fluid to the hydraulic motor. The variable throttle may be configured to control the flow of working fluid and / or the resistance of movement of the piston within the respective cylinder in dependence on one or more parameters, such as for example mass, of the vehicle contacting the platform(s). In one embodiment, each platform may be in communication with a plurality of pistons moveable within respective cylinders on movement of the corresponding platform (for example on a downstroke or upstroke of the corresponding platform). One or more, preferably each, platform is preferably in communication with at least two pistons and respective cylinders. In one embodiment, one or more, preferably each, platform is in communication with at least one pair of pistons and respective cylinders. The at least one pair of pistons may be provided in a self-priming single acting cylinder arrangement. Preferably, each platform is in communication with a first piston moveable within a first cylinder (within the or each pair of pistons and respective cylinders) on depression of the platform, and a second piston moveable within a second cylinder (within the or each pair of pistons and respective cylinders) on raising of the same platform providing the self-priming single acting cylinder arrangement. Preferably, the accumulator(s) comprises one or more fluid reservoirs configured in use to store the received working fluid under pressure. In some embodiments the accumulator includes a plurality of reservoirs arranged as a bank of interconnected modular chambers, each modular chamber has its own isolation valves which enable a single modular, chamber to be removed from the bank of interconnected modular chambers. In some embodiments the plurality of reservoirs (for example modular chambers) are arranged in banks and connected together by one or more common pressure lines. Optionally, the plurality of reservoirs (for example modular chambers) are housed in concrete containers or mounted on a metallic frame. Preferably, the accumulator(s) comprises one or more pressure vessels configured in use to store the received working fluid under pressure, and either operable as pulsation dampers and / or providing direct communication between the accumulator(s) during operation of the system. The system preferably comprises a pressure controller in communication with, and operable to control operation of, a low-pressure valve configured in use to supply, via a low pressure circuit, working fluid to a reservoir (for example low-pressure reservoir). The reservoir may be in communication with a hydraulic motor. For example, the low pressure reservoir may be in communication with a low power / low pressure hydraulic motor. The system preferably comprises one more valves, preferably automatic valves, configured in use to control release of working fluid from one or more accumulators (for example reservoir(s)) to a hydraulic motor. The working fluid may for example comprise air. The system may comprise a pressure controller configured in use to control a low-pressure valve to open a low-pressure (air) circuit to an air powered motor, utilising the air generated from the pressure stroke of the piston within a respective cylinder on movement of a corresponding displaceable platform. In some embodiments the second working fluid (for example air) is in communication with a second motor via an expander. In some embodiments the second working fluid (for example air) powers a second motor via an air storage device, which in turn is connected to an air powered motor. The system may further comprise a control system operable to control flow of working fluid to a hydraulic motor and / or alternator. The system may comprise one or more sensors, for example a plurality of sensors, operable to determine system parameters and to send status signals to the control system. In some embodiments the control system is configured in use to transmit status signals and reports to a remote location via a wireless transmitter. The sensor(s) are preferably configured in use to determine one or more of the following parameters: the number of vehicles passing across the system in a user defined period; vibration levels of the system; temperature of the working fluid(s); pressure of the working fluid(s); condition of components of the system; and any combination thereof. The determined parameterscan be used to record system efficiency and for predictive maintenance purposes of the system. The sensor(s) may be configured in use, in addition or the alternative, to determine one or more of the following parameters: moisture level (saturation levels); air temperature; dew point; hours of daylight, or any combination thereof. The system may further comprise a wireless receiver operable to receive signals from a remote location. The control system may be configured in use to operate, for example automatically, one or more valves (for example control and / or flow valves) located between one or more cylinders and an accumulator; between an accumulator and a hydraulic motor; between a hydraulic motor and an alternator. The system may comprise an alternator configured in use to be connected to an inverter configured to supply electricity supply system or grid or to a battery storage system. The alternator may be connected to an inverter either directly or indirectly. A flywheel (not shown) may be arranged to receive excess energy and stores this temporarily as kinetic energy. The flywheel is preferably connected to a generator / alternator. Rotating parts within the system may be constructed to utilise a flywheel to absorb excess energy and store this as kinetic energy that may be used by other parts of the system. The system may further comprise adjustable means configured in use to vary one or more of: the width of the contact surface of a platform and / or a contact point using a spacer bar strop. The system of the present invention can be adjusted for use in regions with heavier (or lighter) traffic and helps reduce damage to the system during use and associated infrastructure. According to a further aspect of the present invention, there is provided a method of generating electricity using the kinetic energy harvesting system as herein described. The method may further include one or more of: recording an instantaneous amount of electrical energy generated during a predetermined time point of use of the system; and / or recording a total amount of electrical energy generated during a predetermined interval of use; and / or providing real time data relating to the real time generation of electrical energy. A preferred embodiment of the invention will now be described, by way of example only, and with reference to the Figures in which: Brief Description of Figures Figure 1 shows a schematic illustration of a perspective view of an energy harvesting system according to one embodiment of the present invention; and Figure 2 shows an enlarged view of a portion of the energy harvesting system of Figure 1. Detailed Description Referring to the Figures, it can be seen that the kinetic energy harvesting system 1 comprises a plurality of see-saw mechanisms 2. It is however to be understood that the system 1 may comprise a single see-saw mechanism. Each see-saw mechanism 2 comprises a pair of first 4 and second displaceable platforms 6. Each of the first 4 and second 6 displaceable platforms comprises a first end 8a, 8b, an opposed second end 10a, 10b, and an upper surface 12a, 12b extending therebetween, in which the upper surface 12a, 12b provides a contact surface defining a pathway (X-X') for vehicle movement. A pair of side portions 14a, 14b extend between the first 8a, 8b and second 10a, 10b ends of each platform 4, 6. A rigid strut 16 extends between the platforms 4,6 to connect them together in an arrangement where the second end 10a of the first platform 4 is positioned at or adjacent to, and extends substantially parallel to, the second end 10b of the second platform 6. Each of the first 4 and second 6 displaceable platform are moveable between a loaded position when the contact surface 12a, 12b thereof is contacted by a vehicle; and an unloaded position when the contact surface 12a, 12b thereof is free from contact with a vehicle. The upper surface 12a, 12b of each platform 4, 6 is planar. The system 1 further comprises a plurality of torque arms 18, each torque arm 18 being connected to a respective see-saw mechanism and mounted on rotatable shaft 17 such that movement of the first and / or second displaceable platforms 4, 6 between the loaded position and unloaded position causes rotational movement of the shaft 17 causing rotatable movement of each torque arm 18. The rotational axis of the rotatable shaft 17 and torque arm 18 extends substantially perpendicular to the defined pathway and the direction of travel of a vehicle. The system 1 further comprises a pair of pistons 20a, 20b, each piston 20a, 20b being moveable within a respective cylinder 22a, 22b comprising a working fluid. Each piston 20a, 20b is in communication with a respective end of the torque arm 18 such that rotational movement of the torque arm 18 causes translation movement of the piston 20a, 20b within the cylinder 22, 22b to pressurise the working fluid. Each piston 20a, 20b is configured in use to be moveable within the cylinder 22a, 22b in a direction extending substantially perpendicular to the rotational axis of the rotatable shaft 17. Each piston 20a, 20b is configured in use to be moveable within the cylinder 22a, 22b in a direction extending substantially parallel to the direction of movement of the displaceable platforms 4, 6. The longitudinal axis of each piston 20a, 20b and respective cylinder 22a, 22b extends substantially parallel to the direction of movement of the displaceable platforms 4, 6. By arranging the pistons 20a, 20b and respective cylinders 22a, 22b in this way, the system 1 is more efficient and more compact and less prone to damage during use. Furthermore, the system 1 of the present invention enables the vehicle to move onto the see-saw mechanisms without encountering a "speedbump" effect leading to improved energy harvesting. This arrangement provides for the maximum return of power for the shortest stroke length of the piston. The torque arm 18 is arranged to extend substantially perpendicular to the longitudinal axis defined by the pistons 20a, 20b / cylinders 22a, 22b (i.e. to the translation movement of the piston(s) within the respective cylinder(s)). This arrangement helps to provide for vertical transmission of the torque into the cylinder. This arrangement significantly helps to reduce sideloads being exerted onto the piston(s) thereby increasing cylinder life and mechanical efficiency. The longitudinal axis of the pistons / cylinders extends in a direction extending substantially perpendicular to the pathway defined by the displaceable portions 4, 6. It is to be understood that the piston arrangement may comprise any suitable number of pistons and cylinders, each comprising a working fluid. The system 1 further comprises an accumulator (not shown) in fluid communication with the piston arrangement to receive and store pressurised respective working fluid therefrom. The system 1 is adapted to be deployed in a trench in a road or track. Alternatively, the system 1 can be positioned between a pair of ramps positioned on a transport surface. Each displaceable platform 4, 6 is moveable between: an unloaded position (A) in which the contact surface 12a, 12b of the first or second displaceable platform 4, 6 extends above a neutral line level X-X' configured in use to be substantially aligned with an adjacent transport surface 24; and a loaded position (B) in which the contact surface 12a, 12b of the first or second displaceable platform 4, 6 is in contact with and depressed by loading caused by movement of a vehicle onto and / or along the contact surface 12a, 12b of the first or second displaceable platform 4, 6 causing the contact surface 12a, 12b to be positioned lower than in the unloaded position, such that the contact surface 12a, 12b is aligned with the neutral line level X-X'. The kinetic energy harvesting system may further comprise: a hydraulic motor in communication with the accumulator(s) such that the stored pressurised working fluid drives the hydraulic motor; and an alternator configured in use to receive power from the hydraulic motor. On movement of the platform 4,6 from the unloaded position (A) to the loaded position (B), the torque arm 18 is rotated in a first direction causing a piston to move laterally within the respective cylinder to pressurise the corresponding working fluid. As a tyre approaches the system, in an initial phase, it abuts a first end 8a of the first displaceable platform 4. Further rotation of the tyre creates frictional engagement which drives the first end of the first displaceable platform 4 in a downward direction such that the upper surface is aligned with a neutral line extending substantially parallel to the transport surface. Movement of a vehicle across the system of the present invention occurs over two cycles: during a first cycle, the tyre contacts and moves across the contact surface of the first displaceable platform 4 to move the platform from the respective first unloaded position to the loaded position. During a subsequent second cycle, the tyre contacts and moves across the contact surface of the second displaceable platform 6 to move the platform 6 from an unloaded position to the loaded position (which in turn causes the first displaceable platform 4 to be moved to the unloaded position). The system 1 is configured (and in particular the first 4 and second 6 displaceable platforms are configured) such that the tyre traverses both of the contact surfaces of the first and second displaceable platforms 4, 6 within a single turn of the tyre. In particular, the system is configured (and in particular the first 4 and second 6 displaceable platforms are configured) such that the first 4 displaceable platform is contacted with a tyre of a vehicle during a first half turn of the tyre, and such that the second 6 displaceable platform is contacted with the tyre of the vehicle during a subsequent second half turn of the tyre. The system has been found to efficiently extract more energy from the movement of vehicles across the contact surface compared to conventional kinetic energy harvesting systems as a result of the use of a see-saw mechanism of displaceable platforms. The invention has been described by way of examples only and it will be appreciated that variation may be made to the embodiments described, without departing from the scope of the invention as defined by the claims.

Claims

1. A kinetic energy harvesting system for converting mechanical energy into electrical energy, in which the kinetic energy harvesting system is configured in use to extend between adjacent areas of a transport surface to provide a contact surface defining a pathway for a vehicle, and in which the system comprises:at least one see-saw mechanism configured in use to be pivotally mounted, in which the see-saw mechanism comprises:a pair of first and second displaceable platforms, in which each of the first and second displaceable platforms comprises a first end, an opposed second end, and an upper surface extending therebetween, in which the upper surface provides a contact surface defining a pathway for vehicle movement; anda rigid strut connecting the first end of the first platform at or adjacent to the first end of the second platform.in which each of the first and second displaceable platform is moveable between a loaded position when the upper surface thereof is contacted by a vehicle; and an unloaded position when the upper surface thereof is free from contact with a vehicle;a torque arm connected to the at least one see-saw mechanism, in which the torque arm is mounted on a rotatable shaft configured in use to be rotatable on movement of the first and / or second displaceable platforms between the loaded position and unloaded position;at least one piston moveable within a cylinder comprising a working fluid, in which the at least one piston is in communication with the torque arm such that rotational movement of the torque arm causes translation movement of the piston within the cylinder to pressurise the working fluid; andat least one accumulator in fluid communication with the at least one cylinder to receive and store pressurised respective working fluid therefrom;in which the piston(s) is configured in use to be moveable within the cylinder in a direction extending substantially perpendicular to the pathway defined by the displaceable portions.

2. A kinetic energy harvesting system as claimed in claim 1, in which the piston(s) is configured in use to be moveable within the cylinder(s) in a direction extending substantially perpendicular to the rotational axis of the rotatable shaft.

3. A kinetic energy harvesting system as claimed in either of claims 1 and 2, in which the piston(s) is configured in use to be moveable within the cylinder(s) in a direction extending substantially parallel to the direction of movement of the displaceable platforms.

4. A kinetic energy harvesting system as claimed in any preceding claim, in which the longitudinal axis of the piston and respective cylinder extends substantially parallel to the direction of movement of the displaceable platforms.

5. A kinetic energy harvesting system as claimed in any preceding claim, in which the torque arm is arranged to extend substantially perpendicular to the longitudinal axis defined by the piston(s) / cylinder(s).

6. A kinetic energy harvesting system as claimed in any preceding claim, in which the torque arm is in communication with at least one pair of pistons, each moveable within a respective cylinder comprising a working fluid.

7. A kinetic energy harvesting system as claimed in claim 6, in which the or each pair of pistons comprises a first piston and a first cylinder located at or adjacent a first end of the torque arm, and a second piston and second cylinder located at or adjacent a second end of the torque arm.

8. A kinetic energy harvesting system as claimed in any preceding claim, in which the torque arm is configured to be rotatable at or about a central portion located between a first and second opposed end thereof.

9. A kinetic energy harvesting system as claimed in any preceding claim, in which the pathway provides a continuous neutral line level which is substantially flat as the tyre of a vehicle traverses from the transport surface along the system.

10. A kinetic energy harvesting system as claimed in any preceding claim, in which the piston(s) / cylinder(s) is located and spaced away from a side portion of the displaceable platforms.

11. A kinetic energy harvesting system as claimed in any preceding claim, comprising a self-priming single acting cylinder arrangement comprising the at least one piston and cylinder.

12. A kinetic energy harvesting system as claimed in any preceding claim, in which each displaceable platform is moveable between:an unloaded position in which the contact surface of the first or second displaceable platform extends above a neutral line level configured in use to be substantially aligned with an adjacent transport surface; anda loaded position in which the contact surface of the first or second displaceable platform is in contact with and depressed by loading caused by movement of a vehicle ontoand / or along the contact surface of the first or second displaceable platform causing the contact surface to be positioned lower than in the unloaded position, such that the contact surface is aligned with the neutral line level.

13. A method of generating electricity using the kinetic energy harvesting system as claimed in5 any one of claims 1 to 12.21

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