The present invention relates to a power generation assembly, in particular to a power generation assembly for harvesting potential energy from a vehicle, such as a road vehicle, and converting that potential energy into electrical power.

Road vehicles, for example, cars, buses and trucks are propelled along roads using suitable fuels such as petrol, diesel, or gas, or powered by electricity.

In some vehicles where an electric motor is present, either directly driven using overhead power lines for example, or an electric motor driven by a suitable fuel, the gravitational mass of the vehicle can be used to generate power via regenerative braking, where the motor is switched momentarily into a generator, and the load created by the electromagnetic forces are used to slow the vehicle at the same time as recovering electricity into a charging device or battery.

The above mentioned recovery systems are considered micro power generation systems and only usable at microlevel within the vehicle itself.

Large scale power generation for the grid typically uses large turbines driven by large bodies of water (hydro-electric), steam (driven by coal, gas or nuclear fuel), or large arrays of solar panels or arrays of large wind turbines. Other than large hydro-electric systems that have natural water gathering abilities such as natural run-off from hills and mountains, these systems all have a negative environmental impact.

It is an object of the present invention to utilise the mass of a vehicle to generate power on a larger scale without the environment impact associated with known large scale power generation.

Thus, according to the present invention there is provided a road power generation assembly comprising at least one power generation device, the power generation assembly comprising a body configured to be attachable to part of a road assembly, the power generation device including a movable element configured to be engageable with part of a vehicle moving relative to the road assembly in which engagement between the vehicle and the movable element causes the movable element to load a resilient element in a first direction and disengagement of the vehicle from the movable element causes the resilient element to unload and move the movable element in a second direction to drivingly engage the movable element with a generator such that a quantity of energy is transferred from the resilient element to the generator to generate electrical power.

Advantageously, it is the resilient element which causes the movable element to drivingly engage with the generator to generate power when the movable element moves in the second direction as opposed to prior art power generation assemblies which generate power when the movable element moves in the first direction as the vehicle engages with the movable element. By generating the power in the second direction, typically the upwards vertical direction or during the upstroke, the power generated does not vary with the mass and/or the speed of the vehicle as is the case with prior art power generation assemblies which generate power as the movable elements moves in the downwards vertical direction or during the downstroke. The power generated on the upstroke is therefore constant as it depends on a fixed parameter, such as a spring or torsion constant, of the resilient element.

Preferably the movable element is disengaged from the generator when moving in the first direction.

Preferably the quantity of energy transferred to the generator is proportional to a parameter of the resilient element, preferably the resilient element is a compression spring, the compression spring is compressed in the first direction, and the parameter is a spring constant, or the resilient element is a torsion bar, the torsion bar is twisted in the first direction, and the parameter is a torsion constant.

Preferably the quantity of energy transferred to the generator is independent of the mass and/or speed of the vehicle.

Preferably no energy is transferred to the generator when the resilient element moves in the first direction. Preferably the first direction is different to the second direction, preferably the first direction is opposite to the second direction, more preferably, the first direction is vertically downwards and the second direction is vertically upwards.

Preferably the movable element cooperates, preferably engages, with a drive gear which is drivingly connected to the generator, such that movement, preferably linear movement, of the movable element causes the drive gear to rotate.

Preferably the movable element cooperates, preferably engages, with a drive gear which is drivingly connected to the generator, such that movement, preferably linear movement, of the movable element causes the drive gear to rotate.

Preferably the engagement between the movable element and the drive gear is direct engagement, preferably the drive gear is a radial gear and the movable element includes a linear gear such that direct engagement between the radial gear and the linear gear causes the drive gear to rotate.

Preferably the engagement between the movable element and the drive gear is indirect engagement.

Preferably the movable element directly engages with a secondary gear, the secondary gear is fixed to a primary gear, in which the primary gear engages with the drive gear such that movement of the movable element causes the drive gear to rotate.

Preferably the movable element is selectively engagable and disengagable from the generator, preferably selectively engagable and disengagable from a or the drive gear.

Preferably the movable element disengages from the generator or from a or the drive gear when the movable element moves in the first direction, and engages with the generator or with a or the drive gear when the movable element moves in the second direction.

Preferably the movement of the movable element in the first direction disengages the primary gear from the drive gear such that rotation of the secondary gear does not rotate the drive gear, and movement of the movable element in the second direction engages the primary gear with the drive gear such that rotation of the secondary gear rotates the drive gear.

Preferably movement of the movable element in the first direction causes the bearing to move in the slot in the first direction to disengage the primary gear from the drive gear, and movement of the movable element in the second direction causes the bearing to move in the slot in the second direction to engage the primary gear with the drive gear.

Preferably the power generation assembly further comprises a gearbox drivingly connected to, preferably between, the movable element and the generator.

Preferably the gearbox includes a disengagement mechanism to selectively engage and disengage the movable element from the generator.

Preferably only movement of the movable element in the second direction generates electrical power.

Preferably the power generation assembly further comprises at least one energy storage device configured to store energy resulting from movement of the movable element in the first direction and release the stored energy to the generator.

Preferably the energy storage device is at least one or more of a clock spring a flywheel, or a fluid-wheel located on a drive gear.

Preferably the power generation assembly further comprises a ratchet advance which engages with the at least one clock spring to re-tension the clock spring when the movable element moves in the second direction.

Preferably the at least one clock spring is a plurality of clock springs arranged such that the ratchet advance re- tensions each clock spring in sequence when the movable element moves in the second direction. Preferably the movable element engages with a vehicle wheel.

Preferably the movable element cooperates with a drive gear such that linear movement of the movable element causes the drive gear to rotate.

Preferably the movable element cooperates with a drive gear by directly engaging with the drive gear such that linear movement of the movable element causes the drive gear to rotate.

Preferably the drive gear includes a radial gear and the movable element includes a linear gear such that direct engagement between the radial gear and the linear gear causes the drive gear to rotate.

Preferably the resilient element is configured to act against the movable element in a direction opposite the first direction.

Preferably the resilient element causes the movable element to move to an extended position so as to be re-engageable with the vehicle wheel.

Preferably the body includes at least one recess, within which each one of the at least one movable element moves.

Preferably the at least one power generation device is at least two power generation devices arranged adjacently to each other on the body.

Preferably the at least one power generation device is at least two power generation devices arranged oppositely to each other on the body so as to be engageable with a vehicle wheel.

Preferably the movable element is a plunger.

Preferably the movable element directly engages with a wheel of the vehicle. Preferably the body includes at least one recess, within which each one of the at least one movable element (36) moves.

Preferably the body further comprises a fluid storage tank, in which movement of the movable element causes fluid in the fluid storage tank to rotate a fluid-wheel.

Preferably the fluid storage tank includes a spring loaded diaphragm operably connected to the movable element, and an injector fluidly connecting the fluid in the fluid storage tank to the fluid wheel, such that movement of the movable element operates the spring loaded diaphragm to displace fluid and create pressure in the fluid storage tank, forcing fluid to evacuate through the injector and rotate the fluid wheel.

Preferably the power generated by the generator is transmitted to a super capacitor and/or a battery.

Preferably the body locates in a channel of the road assembly.

Preferably the vehicle is one of a car, a truck, or a van, or any other vehicle capable of generating movement relative to a surface upon or within which a power generation assembly is installed.

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figures 1 to 4 are perspective views of a power generation assembly according to one embodiment of the present invention,

Figures 5 to 10 are perspective views of part of road assembly including the power generation assembly of Figure 1 ,

Figure 11 is a perspective view of part of an alternative power generation assembly,

Figure 12 is a perspective view of part of an alternative power generation assembly, Figure 13 is a perspective view of part of an alternative power generation assembly,

Figures 14 and 15 are perspective views of part of an alternative power generation assembly,

Figures 16 and 17 are perspective views of part of an alternative power generation assembly, and

Figures 18 and 19 are perspective views of part of an alternative power generation assembly,

Figure 20 is a perspective view of part of an alternative power generation assembly,

Figures 21 to 25 are perspective, front and side views of part of an alternative power generation assembly, and

Figure 26 is a perspective view of part of an alternative power generation assembly.

In Figures 1 to 4, a power generation assembly 90 according to a first embodiment comprises a main body 22 and a plurality of power generating devices, in this embodiment, four power generation devices 10a, 10b, 10c, 10d. The main body 22 is configured so as to house the power generation devices 10a-d as will be described below.

In Figures 5 and 6, a road assembly in the form of a road 80 has a road surface 82. As can be seen in Figure 6, the main body 22 is sized such that it locates in a gap 84 created in the road 80. Alternatively, as shown in Figures 7 to 10, the main body 22 can be incorporated into a ramp assembly 81 which forms part of the road assembly, and is positioned on, or in some cases, integrated with, the road 80.

In Figures 5 to 10, a vehicle in the form of a car 70 comprises four wheels (front and rear) 72 which are supported on the road surface 82. Each wheel 72 has a tyre with an outer surface 75 which engages with the road surface 82. In Figures 1 and 4, the main body 22 is an elongated hollow box-type structure including a rear wall 24, a front wall (not shown in Figure 1 ) opposite the rear wall 24, left side wall 26, right side wall 28, opposite the left side wall 24, and a base 30 opposite a top cover (not shown). The base 30 includes a downwardly extending portion 32.

It will be appreciated that the main body 22 can be adapted to suit different road and ramp designs.

The main body 22 includes four recessed portions in the form of hollow portions 34 extending upwardly from the base 30.

Each of the four power generation devices 10a-d includes a movable element in the form of plunger 36, a resilient element in the form of helical spring such as a compression spring 38, a gearbox 42, an energy storage device in the form of flywheel 40, and a generator 44. A drive gear 46 including a radial gear 48 is drivingly connected to the gearbox 42 which is also drivingly connected to the flywheel 40 to and the generator 44. The flywheel 40 functions to store and/or smooth the energy supply to the generator 44as the plunger 36 moves upwards under the action of the unloading compression spring 38 as will be described below due to the intermittent nature of the downward plunger 36 movement.

In Figures 7 and 8, each plunger includes a horizontal extension portion 73 (not shown in Figures 1 to 4) which is arranged to sit proud (vertically above) the road surface 82 (or surface 85 of the ramp 85) to engage with the outer surface 75 of the tyre 72 as will be described below. The horizontal extension portion 73 is of sufficient width to enable engagement with the car tyre 75, typically greater than the width of the car tyre (Figure 5). It will also be appreciated that in some embodiments, no horizontal extension portion is required.

The compression spring 38 is defined by a parameter in the form of a spring constant, the value of which is proportional to the amount of power generated. In this embodiment, it will be appreciated that the spring constant is selected to provide sufficient power to the generator. It will be understood the spring constant is sufficiently high to return the plunger to its starting or extended position where the plunger can engage with a vehicle as will be described further below.

In this embodiment, the gearbox 42 is positioned between the flywheel (40) and the drive gear (36) In alternative embodiments the gearbox 42 can be positioned between the flywheel and the generator.. Whether or not the drive gear directly drives the flywheel, or drives the flywheel via the gearbox, and the gear ratios selected, is dependent on the rotational speed required for the flywheel to generate a given power output from the generator which is dependent on the frequency of load application to the plunger, i.e. frequency of the vehicles engaging with the plunger, and the load itself on the plunger which is determined based on the spring constant of the compression spring A high spring constant will generate more power, but will require a higher mass of vehicle to cause compression. Conversely, a lower spring constant will require a lower mass of vehicle to cause compression, but will generate less power

In Figures 3 and 8, the plunger 36 and the compression spring 38 both locate inside the hollow portion 34 such that the helical spring 36 is positioned below the plunger 36 and is fixed at one end to the base 30 of the body 22. The plunger has a length L such that an exposed portion of either the plunger or the horizontal extension portion of the plunger 73 protrudes above the cover 25 when the helical spring 38 is in an uncompressed state by a length LE which is sufficient to enable engagement with the lower surface of the outer portion 75 of the car wheel 72 when the car 70 is moving along the road 80. The horizontal extension portion 73 of the plunger 36 has a rounded upper surface 37 which minimises the rolling resistance when the road wheels 72 engage with the plunger 36. The plunger 36 includes a linear gear 50 configured so as to engage with the radial gear 48 and cause the drive gear 46 to rotate when the plunger 36 moves as will be described below. The drive gear 46 extends into the hollow portion 34 to enable engagement between the radial gear 48 and the linear gear 50.

It can be seen from Figures 1 and 4 that plungers 36a, 36c are adjacent to each other so that a wheel 72 on one side of the car running on the road 80 sequentially engages with plungers 36a, 36c. It can be similarly seen that plungers 36b, 36d are adjacent each other so that an opposite side wheel 72 running on the road 80 sequentially engages with plungers 36ca,36d. It can also be seen that plungers 36a, 36b are opposite each other so that opposite wheels 72 (front or rear wheels) running on the road surface 82 simultaneously engage with plungers 36a, 36b. It can similarly be seen that plungers 36c, 36d are opposite each other so that opposite wheels 72 (front or rear wheels) running on the road surface 82 simultaneously engage with plungers 36c, 36d.

It will be understood that the power generation assembly need not be limited to four power generation devices. For example, the power generation assembly could include a single power generation device or more than two power generation devices positioned adjacently. It will be further understood that the power generation devices need not be positioned so as to be engaged by both opposite wheels 72c, 72d, that is, the power generation devices can be positioned adjacent to each other on one side of the body 22 only. Increasing the number of power generation devices within the power generation assembly increases the electrical power generated. Similarly, increasing the number of power generation assemblies increases the electrical power generated.

Each of the individual generators 44 are electrically connected to a super capacitor (not shown) and/or a battery (not shown) to store the power generated from each power generation device. The super capacitor and/or battery can be housed within the power generation assembly itself or separate from the assembly and electrically connected to the power generation assembly. Where multiple power generation assemblies are installed, a common battery and/or supercapacitor can be used to store the energy generated from each power generation assembly.

The power generation assemblies can be installed at any position, straight or curved, on the road assembly. Typically however the assemblies are located close to infrastructure which enables efficient transfer of the power generated by the power generation assemblies to where the generated power is to be used or fed into an electrical network for subsequent distribution. By way of example, positioning the power generation assembly in a car park, be that the approach to the car park or within a parking space is beneficial, particularly if the car park serves buildings requiring the use of electrical power. The power generation device assembly (90) operates as follows:

Firstly the main body 22 is installed in the road 80. Typically a channel 87 will be removed from the road to enable the main body 22 to locate. It can be seen in Figures 2, 3, 5 and 6 that after installation, the horizontal extension portion 73 of the plunger 36 of each power generation device 10a-d extends above the surface 82 of the road 80 or the surface 85 of the ramp 81 sufficiently so as to be engageable with the outer surface 75 of the car wheel 72.

In Figures 5, 6, 9 and 10, when the car 70 is moving along the road 80 in a conventional manner, the outer surface 75 of each wheel 72 of the car engages with and depresses each horizontal extension portion 73 of the plunger 36 of the power generation device in a first direction or linearly downward direction Yi which is substantially perpendicular to an axis (X) defined by the direction of the road 80, from an extended position to a depressed position.

As the plungers 36c, 36d are depressed or move in the linearly downward direction Yi , the linear gear 50 of the plunger 36c, 36d engages with the radial gear 48 on the drive gear 46 to rotate the drive gear 46. The gearbox 42 includes a disengage mechanism (not shown) which is configured as is known in the art to disengage the drive gear 46 from the generator 44 when the plungers 36c, 36d move in the linearly downward direction Yi such that no power is transferred to the generator (44) in the first direction. As the plungers 36c, 36d move in the linearly downwards direction, the compression spring 38 is loaded due to the mass of the vehicle. Once the front wheels 72c, d have simultaneously rolled over plungers 36c, 36d, the plungers 36c, 36d, under the action of the compression spring 38, are returned to their extended position in a second or upwards direction Y2 ready to be re-engaged sequentially with the rear wheels 72a, b of the car 70. The gearbox 42 is configured to re-engage the drive gear 46 with the generator 44 when the plunger moves in the upwards direction such that movement of the plunger causes rotation of the drive gear 46, and by being drivingly connected, rotation of the flywheel 40, the gearbox 42 and the generator 44 to generate electrical power. It will be appreciated therefore that electrical power is only generated when the plunger is moving in the upwards direction under the action of the loaded compression spring with the amount of energy transferred from the spring to the generator, and therefore the electrical power generated, not being dependent on the mass of the vehicle. The vehicle acts solely to load the compression spring, and it is the unloading of the compression spring as the vehicle disengages from the plunger which energy is transferred to the generator

The operation described above is with reference to one power generation assembly. It will be understood that where multiple power generation assemblies are installed, the same principle of operation applies.

It will be understood that the embodiments above have been described with reference to a road, and to a road including a ramp.

It will also be understood that in the above embodiments, the energy storage device is a flywheel 40 even though Figures 5, 6, 9 and 10 show an alternative energy storage device in the form of a fluid wheel which will be described further below.

Figure 11 shows part of an alternative power generation assembly 190 according to a second embodiment which is identical to that described in Figures 1 to 10 except the power generation device includes an additional energy storage device in the form of a clock spring 160 positioned on the drive gear 146.

In operation, as the plunger 136 moves upwards after the compression spring has been compressed, the clock spring 160 is wound up and acts as an energy store which unwinds, irrespective of the plunger position, to provide continuity of power to the generator until fully unwound in addition to the continuity of power provided by the flywheel. The clock spring rate can be configured to provide continuous power to the generator according to the frequency of plunger activation by the car. Specifically, where the time interval between car/plunger interaction is high, then the clock spring will need to maintain continuity of power to the generator for longer. The clock spring is configured such that it is wound up in one direction when the plunger moves upwards, and then released from the outside, for example, using a ratchet, or at least a pawl to wind the centre of the clock spring in one direction before the outside is released.

In an alternative embodiment (not shown) to Figure 11 , the power generation assembly does not include a flywheel, with the clock spring functioning as the only energy storage device.

Figure 12 show an alternative power generation assembly 290 which is identical to that described in Figures 1 to 11 except the power generation device includes an additional energy storage device in the form of a fluid-wheel 291 which is drivingly connected to the drive gear 246, the flywheel 240, the gearbox 242 and the generator 244. In this embodiment the drive gear 246 is connected directly to the flywheel 240. The horizontal extension portion is not shown in Figure 12.

Alternatively, as shown in Figure 13, the flywheel 240 can be positioned on the generator 244 side of the fluid wheel 291 and the drive gear 246 connected directly to the gearbox 242.

The fluid wheel includes an injector 292 and a multiple fluid collectors 293 which are fed fluid by the injector 292 from a fluid tank 295.

In operation, as the plunger 236 moves upwards, the fluid collectors 293 rotate by virtue of being drivingly connected to the drive gear 246 (via the flywheel 240) and act as an energy store to provide continuity of power to the generator.

In an alternative embodiment (not shown) to Figures 12 and 13, the power generation assembly does not include a flywheel, with the fluid-wheel functioning as the only energy storage device.

Figures 14 and 15 show an alternative power generation assembly 390 which is identical to the embodiment of Figures 12 and 13 except an additional storage device in the form of a clock spring 360 positioned on a drive gear 346 is provided as described in relation to the embodiment of Figure 11 .

In operation, as the plunger 336 moves upwards, the clock spring 360 is wound up and acts as an energy store which unwinds to provide continuity of power to the generator until fully unwound in addition to the continuity of power provided by the flywheel 340 and/or the fluid wheel 391 .

Figures 16 and 17 show an alternative power generation assembly 490 which is identical to the embodiment of Figure 13 except that a lever mechanism 493 is connected to the plunger 436 such that upwards movement of the plunger 436 also presses the lever mechanism 493 which operates a spring-loaded diaphragm 494 in a fluid tank 495. A spring or series of springs (not shown) are positioned under the diaphragm 494 so that as the diaphragm is pressed to the bottom of the tank, the spring pressure under it creates the fluid pressure through the injector as will be described below. It will be understood that the horizontal extension portion of the plunger 436 is not shown in Figure 16.

In operation, upwards movement of the plunger 436 causes the lever mechanism 493 to move the diaphragm 493 to the bottom of the fluid tank 495, with the result that fluid in the fluid tank 494 is displaced to the top of the diaphragm 494. The diaphragm 494 is then pushed back upwards under spring load creating pressure, forcing fluid to evacuate through the injector 492 and spin the fluid wheel 491 , thereby creating an energy store in the displaced fluid, and providing continuity of power to the generator 444 for a prolonged period.

An alternative power generation assembly 590 is shown in Figures 18 and 19 which is identical to the embodiment of Figures 14 and 15 except that two of the fluid tanks 595 are in a separate unit from the body 522.

An alternative power generation assembly 690 is shown in Figure 20 which is identical to the embodiment of Figures 14 and 15 except that the clock spring 660 includes a ratchet advance 697 positioned on drive gear 646 which functions to re-tension the clock spring 660 every time the plunger 636 moves upwards. It will be appreciated that the use of a ratchet device is not limited to embodiments with a fluid wheel or any other energy storage device other than the clock spring with which the ratchet device interacts. It will also be

It will be understood that the purpose of the additional ratchet in the embodiment of Figure 19 is to advance the spring or springs for engagement with every wheel of the car as opposed to winding up the clock spring a single time.

In an alternative embodiment (not shown), multiple progressive clock springs are provided in combination with the ratchet advance to re-tension each one of the multiples springs in sequence every time the plunger moves upwards.

In the embodiments of Figures 1 to 20 described above, movement of the plunger in the upwards or second direction is transferred to the generator, and movement of the plunger in the downwards direction is not transferred to the generator due to the disengagement mechanism of the gearbox.

In the embodiment of Figure 20 to 25, part of an alternative power generation assembly 790 is shown which is identical to the embodiments of Figures 1 to 20, except that the gearbox 740 does not include a disengagement mechanism to prevent movement of the plunger 736 in the downwards direction being transferred to the generator 744.

The power generation assembly 790 comprises a main body 722 and is shown in simplified form with only one power generating device 710.

The power generation device 710 includes a movable element in the form a plunger 736 and a resilient element in the form of a compression spring 738.

In Figure 22 (with all components removed), the body 722 includes a bearing slot 723 into which a bearing 727 (Figures 23 and 24) slidingly locates and a guide slot 743 into which the plunger 736 slidingly locates. In Figure 25, the body 22 is removed to show the bearing 727. A primary gear 741 and a secondary gear 739 which are fixed relative to each other, are provided on the bearing 727 such that the primary gear 741 and a secondary gear 739 can rotate about the bearing 727, and the bearing 727 can move in an upwards and downwards direction. A drive gear 746 is also rotatably mounted on the body 722.

The primary gear 741 is selectively engaged and disengaged from the drive gear 746 as follows:

In Figure 23 (the disengaged position), when the plunger 736 is moved in the downwards direction under the action of the car, the plunger 736 is guided in the guide slot 743, acts on and loads the compression spring 738, and engages with the secondary gear 739 to move both the secondary gear 739 and the primary gear 741 , which are fixed to each other, in the bearing slot 727 in the downwards direction, disengaging the primary gear 741 from the drive gear 746, and rotate both the secondary gear 739 and the primary gear 741 about the bearing 727. When the secondary gear 739 and the primary gear 741 are rotating, the primary gear 741 is not engaged with the drive gear 746, and therefore the drive gear 746 does not rotate and energy is not transferred to the generator 744.

In Figure 24 (the engaged position), when the plunger 736 is moved in the upwards direction under the action of the loaded compression spring 738, both the secondary gear 739 and the primary gear 741 are moved in the bearing slot 727 in the upwards direction, re-engaging the primary gear 741 with the drive gear 746, and rotate both the secondary gear 739 and the primary gear 741 about the bearing 727. When the secondary gear 739 and the primary gear 741 are rotating, the primary gear 741 is engaged with the drive gear 746, and therefore the drive gear 746 does rotate and energy is transferred to the generator 744.

It will be understood that the bearing slot 723 need be of sufficient length to allow the drive gear 746 and the primary gear 741 to physically disengage from each other.

Operation of the power generation assembly 790 is identical to the operation of embodiments of Figures 1 to 20 other than the mechanism by which the drive gear and plunger are selectively engaged and disengaged as described above. In the embodiment of Figure 26, part of an alternative power generation assembly 890 is shown which is identical to the embodiments of Figures 21 to 25, except that the compression spring is replaced by a resilient element in the form of a torsion bar 838.

The torsion bar 838 has a parameter in the form of a torsion constant which can be selected in the same as described above in relation to the compression spring constant.

The torsion bar 838 comprises a first part 851 and a second part 853 which is rotationally fixed to the first part 851 and to the body 822 such that movement of the plunger 836 under the action of a car in a downwards direction moves the first part 851 in a downwards direction and twists the second part 853 to load the torsion bar 838. When the car disengages from the plunger 836 the first part 838 acts on the plunger 836 to transfer energy to the generator (not shown) via the secondary gear 841 , the primary gear 839 and the drive gear 846 in the same way as described above in relation to the compression spring 738.

In the above embodiments, a braking mechanism (not shown) can be used to control the speed of rotation in the generator and to control one or more of the following, a) the output time b) the rotational speed c) the release of the energy from the torsion bar d) the release of the energy from the spring.

It will be understood that in relation to the type and number of energy storage devices is largely dependent on the load being applied to the plunger, that is, the mass of the vehicle, and the frequency with which the plunger is depressed, which will depend on the frequency of vehicles travelling on the road.