Various different types of electrical generators for converting mechanical energy into electrical energy exist. Some of the known types of generators require a fuel to produce the mechanical energy required for generating electricity. Others, for example turbines, utilise energy from natural resources such as rivers and seas which is advantageous in that this energy is available at no cost. However, turbines often are relatively expensive to construct and/or maintain. Also, electrical power generated by a turbine usually has to be transmitted to one or more locations remote from the turbine, and power losses occurring during such transmissions of electrical power can make it impractical to utilise the energy of moving water in a river or a sea.

It is an object of the present invention to provide an alternative device for generating electrical power from an energy source which is available at no cost.

SUMMARY OF THE INVENTION According to the invention there is provided a device for generating electrical power comprising: a deformable fluid container in the form of a mat which is locatable in the path of vehicles travelling along a road so as to be deformed by the wheels of the vehicles as the vehicles pass over the mat, the container defining: a chamber for holding a fluid, an inlet for allowing fluid into the chamber, and an outlet for allowing fluid out of the chamber; a turbine in fluid communication with the chamber inlet and the chamber outlet so that fluid flowing out of the chamber through the outlet is directed through the turbine and back into the chamber via the inlet ; a one-way valve for allowing fluid to exit the chamber through the outlet when loads applied to the mat by one or more vehicles on the mat increase the fluid pressure within the chamber; and a one-way valve for allowing fluid to enter the chamber through the inlet when the fluid pressure within the chamber decreases.

The device may include a reservoir which is located between the chamber outiet and the turbine and which is elevated relative to the chamber so that fluid exiting the chamber is raised into the reservoir and subsequently gravity feeds through the turbine and back into the chamber.

In a preferred embodiment of the invention, the chamber includes a plurality of partitions between the inlet and the outlet, and the mat includes an on- ramp at a first end thereof and an off-ramp at a second end thereof to facilitate the passing of the vehicles over the mat.

The mat may carry a series of spaced-apart brackets which are designed to co-operate with holding-down bolts so as to secure the mat relative to a road surface.

Preferably, at least a portion of the mat is formed from a reinforced, synthetic rubber.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a partially broken away plan view of a device according to the present invention; Figure 2 shows a cross-sectional view along the line 2-2 in Figure 1; Figure 3 shows a cross-sectional view along the line 3-3 in Figure 1; and Figure 4 shows a partially broken away plan view of another embodiment of the device of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Figure 1 of the accompanying drawings illustrates a device for generating electrical power according to the present invention. The device is designated generally with the reference numeral 10 and includes a deformable fluid container in the form of a mat 12, and a turbine 14 which is connected to the mat by means of conduits 16 and 18.

The mat 12 in this embodiment is formed predominantly from a reinforced synthetic rubber, and includes integrally formed ramps 20A and 20B which facilitate the passing of a vehicle over the mat and integrally formed brackets 22 for securing the mat relative to a road surface 24. With reference also to Figures 2 and 3 of the drawings, the mat 12 defines a chamber 26 between an upper wall 28 and a lower wall 30 thereof. The chamber 26 is seen to include a plurality of partitions 32 which extend laterally across the mat between two opposed channels 34 on either side of the chamber. An inlet 36 allows fluid to flow into the chamber 26 and an outlet 38 allows fluid to be discharged from the chamber.

The outlet 38 leads into the conduit 16, as illustrated, so that fluid discharged from the chamber is conveyed to the turbine 14 along this conduit. Similarly, the conduit 18 leads to the inlet 36 so that fluid passing through the turbine is conveyed back to the chamber 26 via the inlet.

Referring in particular to Figure 1, a one-way valve 40 is provided on the conduit 16 adjacent the outlet 38 for preventing fluid from flowing into the chamber 26 via the outlet, and a one-way valve 42 is provided on the conduit 18 adjacent the inlet for preventing fluid from flowing out of the chamber via the inlet. In this way, fluid can be circulated through the system in the direction of the arrows A in Figure 1. Additional valves (not illustrated) are provided on the conduits 16 and 18 for introducing water into the system or draining water from the system.

In practice, the mat 12 is secured relative to a road surface 24 by placing the mat over the road surface and securing the brackets 22 to the ground with holding-down bolts (not shown). The mat is bolted down to the road surface so that the ramps 20A and 20B are positioned as illustrated in Figure 1. The conduits 16 and 18 are then connected to the inlet 36 and the outlet 38, and the turbine 14 is connected to the conduits so as to form a flow path from the outlet to the inlet. If desired, trenches may be excavated for the conduits 16 and 18 so that these conduits once installed are concealed below ground level. Thereafter, water is introduced into the system until the water pressure in the system reaches a predetermined value. For this purpose, a pressure gauge (not shown) is provided, typically on one of the conduits 16 and 18.

As vehicles (not illustrated) travelling along the road surface 24 pass over the mat 12, they apply loads to the mat which cause the water pressure in the chamber 26 to increase. The one-way valves 40 and 42 regulate the water pressure in the chamber 26 by allowing water to flow between this chamber and the conduits 16 and 18. Accordingly, when the number of vehicles travelling onto the mat exceeds the number of vehicles travelling off the mat so as to cause a resultant increase in the water pressure in the chamber 26, the one-way valve 40 allows water in the chamber to flow into the conduit 16, and as the number of vehicles travelling off the mat exceeds the number of vehicles travelling onto the mat so as to cause a resultant decrease in the water pressure in the chamber, the one-way valve 42 allows water to flow from the conduit 18 back into the chamber 26. In this way, as vehicles travelling along the road surface 24 pass over the mat 12, water is circulated through the system so as to drive the turbine 14. In this embodiment of the invention, the turbine is connectable to one or more rechargeable batteries so that the energy transferred from the vehicles to water in the chamber 26 is used to charge the batteries via the turbine 14. Alternatively, the turbine may be arranged to supply electrical power to a transformer linked to the mains power supply.

Figure 4 illustrates another embodiment of the device according to the present invention in which components corresponding to components in Figure 1 have been designated with the same reference numerals as those used in Figure 1. As can be seen, apart from the presence of a reservoir 15 on the conduit 16, the device is basically the same as that of the first embodiment.

The reservoir 15 is elevated relative to the chamber 26 so that water exiting the chamber is raised into the reservoir along the conduit 16 and then gravity feeds through the turbine 14 and back to the chamber 26 along the conduit 18. To increase the output of the turbine, several chambers may be linked to a single, central reservoir and a single turbine.

In the Figure 4 embodiment, the reservoir 15 is used to regulate the flow of fluid to the turbine 14 and is arranged so that water can be stored temporarily in the reservoir and selectively released to drive the turbine when required.

A major advantage of the device according to the embodiments of the invention described above is that it utilises energy in moving vehicles travelling along a road to generate electrical power. Accordingly, by locating one or more of the devices 10 on a relatively busy road, electrical power can be generated from an energy source which is readily available at no cost.