GB2542205A

GB2542205A - Hydraulic wind engine

Info

Publication number: GB2542205A
Application number: GB1516240.7A
Authority: GB
Inventors: Young Alex
Original assignee: Summit Associates Ltd
Current assignee: Summit Associates Ltd
Priority date: 2015-09-14
Filing date: 2015-09-14
Publication date: 2017-03-15
Also published as: GB201516240D0

Abstract

A wind engine 1, comprising a housing 7, and a pair of wind catching surfaces 2, 3, which are slidably movable within the housing and each have an open configuration and a closed configuration, wherein one wind catching surface is in the open configuration whilst the other is in the closed. The engine also comprises a hydraulic system, including a first piston assembly 4 and a second piston assembly 5, where each piston assembly is attached to one of the wind catching surfaces and the pistons are hydraulically coupled to one another to form a hydraulic loop. When a wind force acts upon one of the wind catching surfaces in its closed configuration, the wind catching surface moves slidably within the housing. This drives the respective coupled piston assembly which creates a pressure differential in the hydraulic loop. The pressure differential drives the other piston assembly and the wind catching surface to which it is coupled. Preferably, the wind catching surface is a mechanical iris. Alternatively, the surface may be a panel, or fabric which may furl and unfurl. The housing may comprise a tube 8 within which wind capturing surfaces are located, or the housing may comprise two tubes, each containing a wind capturing surface. The tubes may have a circular cross section.

Description

HYDRAULIC WIND ENGINE

Field of the Invention

The present invention relates to the field of wind engine design, in particular to the field of wind engines having a housing and a first wind catching surface and second wind catching surface, each wind catching surface being slidably movable within the housing.

Background of the Invention

The present invention provides a new wind engine that is able to generate usable torque for the purposes of generating electricity or otherwise.

The energy of the wind can be harnessed to generate useful work. In traditional wind turbines, energy is transferred to a plurality of blades through lift forces that rotate the blades about a horizontal or vertical axis. This mechanical rotation is then typically transferred to a generator for electricity generation.

The forces that act upon the blades are split between lift and drag forces. Typical current turbines are designed to maximise the lift forces acting on the blades and minimise drag forces that act against the desired direction of rotation. Although these designs are very effective at minimising drag forces, drag cannot be eliminated entirely and reduces the efficiency of the turbine. The mechanical rotation of the blades is typically transmitted to the generator through a mechanical gearbox system to increase the rotational speed to improve electrical generation. This mechanical transmission and gearing is a major source of failures, efficiency reduction, weight and maintenance costs.

Typical horizontal or vertical axis wind turbines now accommodate variable rotational frequency, this approach maximises the amount of energy extracted from the wind, but requires the use of costly power electronics to produce grid compatible frequency electricity. This conversion is a further source of energy loss and failure.

These turbines are unable to extract the additional energy in gusty wind conditions.

Turbulent gusts can damage horizontal or vertical axis wind turbines. Additionally, above certain wind speeds these turbines need to be shut down to protect the turbine system from damage.

At high wind speeds HAWT’s spin faster and generate more electricity, but as their rotational speed increases the apparent direction of the oncoming wind changes. This change in angle changes the angle at which lift forces act, so that they move from acting in a direction that induces rotational movement to a direction that acts downwind from the turbine blades, with less force acting in the direction of rotation. At high rotational speeds a substantial amount of the torque generated by HAWTs is not utilised to generate electricity. US4238171A describes a reciprocating wind engine with openable panels. The cooperating panels are attached to either end of a crankshaft. As wind strikes the surface of one of the panels the crankshaft is moved. The first panel is moved toward the crankshaft and the second panel is pulled toward the crankshaft from the opposite side. When both panels are adjacent the crankshaft, the first panel opens to allow the wind to pass there through into contact with the second panel. As wind strikes the second panel it is forced away from the first panel and the first panel is pushed away to complete one cycle of operation.

The use of a mechanical crankshaft is a form of mechanical transmission. Mechanical transmission and gearing can be a source of failures, efficiency reduction and maintenance costs. Additionally, a crankshaft is comparatively heavy and would therefore require a high wind cut-in speed.

The energy generated by the reciprocating wind engine will require conversion to grid compatible frequencies. This conversion is a further source of energy loss and failure. EP2154368(A2) contains a general discussion of the use of hydraulics for transmission. The patent discusses wind engine systems (generically) with hydraulic energy transmission with non-symmetric actuation. The non-symmetric actuation may be caused by valve control and mechanical means for controlling the actuation of the pistons.

It is an object of this invention to provide a wind engine with improved features, including the capability to harvest energy from the wind in a wide range of wind speeds and levels of turbulence.

Summary of the Invention

Accordingly, the present invention aims to solve the above problems by providing, according to a first aspect, a wind engine comprising a housing, a first wind catching surface, a second wind catching surface and a hydraulic system. Each wind catching surface being slidably movable within the housing and having an open configuration and a closed configuration. When one wind catching surface is in the open configuration the other wind catching surface is in the closed configuration. The hydraulic system includes a first piston assembly and a second piston assembly. The first piston assembly is mechanically coupled to the first wind catching surface. The second piston assembly is mechanically coupled to the second wind catching surface. The first piston assembly and the second piston assembly are hydraulically coupled to one another to form a hydraulic loop.

When a wind force acts upon one of the first and second wind catching surfaces in its closed configuration it will cause the wind catching surface to move slidably within the housing. This drives the respective coupled piston assembly which creates a pressure differential in the hydraulic loop. The resulting pressure differential drives the other piston assembly and the other of the first and second wind catching surface to which it is mechanically coupled.

In this way the wind engine of the present invention can convert wind energy into a pressure differential.

The first wind catching surface is slidably moveable between a windward position and a leeward position. The second wind catching surface is slidably moveable between a windward position and a leeward position.

In operation the wind catching surface in the closed configuration catches the wind and moves in the direction of the wind. This drives the piston assembly to which it is attached and this increases the hydraulic pressure in the hydraulic system. At the same time the other wind catching surface is in the open configuration. The increased hydraulic pressure moves the open wind catching surface against the direction of the wind.

Whilst moving against the wind the wind catching surface is in the open configuration and whilst moving in the direction of the wind the wind catching surface is in the closed configuration. At the point of maximum extension of the pistons of the piston assembly attached to the wind catching surface, the wind catching surface closes. At the point of minimum extension of the pistons of the piston assembly attached to the wind catching surface the wind catching surface opens.

In this way the first wind catching surface and the second wind catching surface operate in a reciprocal manner.

The forces acting on the wind catching surface of a wind engine of the present invention always act in the direction that’s most efficient for electricity generation. In the case of traditional HAWTs the force acting on HAWT blades changes direction as the rotation speed increases. This means that not all of the force is useable, for example to generate electricity. The wind engine of the present invention does not have this problem.

In this way the wind engine of the present invention is able to more efficiently and consistently convert wind energy over a range of wind directions.

The wind engine of the present invention will operate at good efficiency over a wide range of wind speeds. HAWTs are designed for a very limited wind speed range, offering poor efficiency outside this range.

In high wind speeds, the open configuration may be partially open and the closed configuration may be partially closed. The partially closed configuration is such that only some of the potential wind force (the wind force that could act on the ‘fully’ closed configuration) acts on the wind catching surface. These configurations prevent any damage to the turbine system in high wind speeds.

This capability of operating in a partial configuration advantageously enables the wind engine of the present invention to operate at full capacity in very high wind speeds, whereas other designs forming part of the prior art would need to fully shut down to prevent damage.

In this way the wind engine of the present invention is able to more efficiently and consistently convert wind energy over a range of wind speeds.

Turbulent gusts can damage HAWTs, but the additional energy contained within the gust is captured by the wind engine of the present invention and converted to electricity without damaging the turbine.

The wind engine of the present invention works on pressure differentials rather than wind speed. Therefore, turbulent conditions won’t affect the generating capacity of the wind engine of the present invention.

In this way the wind engine of the present invention is able to more efficiently and consistently convert wind energy even in gusty or turbulent conditions.

The frequency of operation is very low, so won’t generate any eigenfrequencies in the structure. The slow motion of the wind catching surfaces will mean that they will produce little, if any, noise in operation.

In this way the wind engine of the present invention provides a more environmentally friendly and robust wind engine than traditional wind turbines.

The wind engine of the present invention utilises a hydraulic system. This reduces the weight and cost of the transmission system from that of standard mechanical gearing for wind turbines. The hydraulic system is easier and cheaper to maintain and monitor than mechanical transmission systems. The hydraulic system is also more reliable than mechanical transmission systems due to the reduction in moving parts.

The wind engine of the present invention does not require the complex and costly blade pitch control systems of traditional HAWTs, further reducing the costs over existing designs.

The wind engine of the present invention could also be used for grid frequency regulation in conjunction with the grid operator.

In this way the wind engine of the present invention is able to more efficiently, cheaply and consistently convert wind energy.

Optional features of the invention will now be set out. These are applicable singly or in any combination with any aspect of the invention.

The first wind catching surface and the second wind catching surface may comprise any surface that is non-porous to the wind. In this way when the first wind catching surface or the second wind catching surface is in the closed configuration the wind pressure will apply a force to the wind catching surface and move it in the direction of the wind.

In some embodiments one or more of the first wind catching surface and the second wind catching surface are selected from a mechanical iris, at least one panel or a fabric surface.

The at least one panel may be moveable from a position tangential to the wind to a position parallel to the wind. In some embodiments there are a plurality of panels each moveable from a position tangential to the wind to a position parallel to the wind making up one or more of the first wind catching surface or second wind catching surface. For example both the first wind catching surface and the second wind catching surface are a plurality of panels. In some embodiments exactly one panel moveable from a position tangential to the wind to a position parallel to the wind makes up one or more of the first wind catching surface or second wind catching surface. For example both the first wind catching surface and the second wind catching surface is exactly one panel.

The fabric surface may be such that it furls and unfurls providing an open and a closed configuration respectively. In some embodiments one or more of the first wind catching surface and the second wind catching surface is a fabric surface. For example both the first wind catching surface and the second wind catching surface are fabric surfaces.

In some embodiments one or more of the first wind catching surface and the second wind catching surface is a mechanical iris. For example both the first wind catching surface and the second wind catching surface are mechanical irises.

The term mechanical iris as used herein refers to a device having a plurality of moveable leaves or blades. The leaves or blades can move between an open configuration and a closed configuration, creating an adjustable aperture. The leaves or blades may be pivoted at one end. A mechanical iris is also known as a mechanical iris diaphragm.

In some embodiments the iris leaves or blades have upstands or flanges. The upstands or flanges may be on the leeward leading edge or the trailing windward edge of the iris leaves or blades.

In this way, the iris leaves or blades are strengthened such that they are sufficiently strong and rigid to withstand the pressure applied to them from high winds.

When the mechanical iris is closed the wind pressure will apply a force to the mechanical iris and move it in the direction of the wind. When the mechanical iris is open, it provides a fluid pathway for the wind through the body of the iris. This means that the open iris can be moved more easily against the wind (as compared to a closed iris).

In some embodiments the wind engine further comprises a wind catching surface control means. The wind catching surface control means controls the opening and closing of the first wind catching surface and the second wind catching surface.

Optionally, the wind catching surface control means is an electrical motor, an electromagnetic means or a hydraulic actuator.

For example, when the wind catching surface is a mechanical iris an electrical motor can be employed to rotate a cog which opens/closes the iris; an electromagnetic means can use an electromagnet to rotate a cog which opens/closes the iris; and a hydraulic actuator can be employed to push the iris leaves open/closed.

Optionally the wind catching surface control means comprises at least one sensor. It may be that the at least one sensor is within the wind engine.

The sensor may detect the motion of the first wind catching surface and the second wind catching surface within the housing. When the first wind catching surface and second wind catching surface reach a predetermined point in the housing the sensor detects this and the wind catching surface control means opens or closes the wind catching surfaces. The predetermined point may be at the fullest extent of the range of motion of the first wind catching surface and the second wind catching surface.

The sensor may detect the motion of the first piston assembly and the second piston assembly. When one or other of the piston assemblies reaches its maximum compression or expansion the sensor can signal the wind catching surface control means to open or close the wind catching surface to which the piston assembly is coupled.

In this way the opening and closing motion of the first and second wind catching surfaces is controlled and may be synchronous.

The wind catching surface control means mechanism can also be utilised to partially open and close the first wind catching surface or the second wind catching surface. It may be that a wind speed detector is connected to the wind catching surface control means.

In this way the wind engine is protected in the event of damagingly high wind speeds

In some embodiments the housing comprises one tube within which both the first wind catching surface and the second wind catching surface are located and are slidably movable.

The term tube as used herein refers to an elongate hollow structure having a uniform cross-section along its length. The cross-section in a direction transverse to the elongate axis may take any suitable shape. It may, for example be: circular, square, triangular or hexagonal cross-section. Preferably, the cross-section is circular.

Preferably, the tube includes an outer tubular surface and an inner tubular surface, the inner tubular surface defining an elongate cavity within which the wind catching surfaces are located. The first wind catching surface and second wind catching surface are slidably mounted to the housing so that they are slidably movable along the longitudinal axis of the tube.

Optionally, the first wind catching surface operates between two end points, both end points located within in one half of the tube and the second wind catching surface operates between two end points located within the second half of the tube.

In some embodiments the housing comprises two tubes; and wherein the first wind catching surface is located within in one of the two tubes and the second wind catching surface is located within the other of the two tubes.

Preferably, the tubes include an outer tubular surface and an inner tubular surface, the inner tubular surface defining an elongate cavity within which the wind catching surface is located. The wind catching surfaces are slidably mounted to the housing so that they are slidably movable along the longitudinal axis of the tube.

Optionally, the wind catching surfaces operate between two end points, one end point located close to one end of the tube and the other end point located close to the other end of the tube.

In some embodiments housing further comprises a wind focussing rim. The rim may be wider than the cross section of the rest of the housing. Optionally, the rim may form a frustum for example the rim may be frustopyramidal or frustoconical. Optionally, the housing may have a wind focussing rim at both ends.

In this way a larger surface area for funnelling the wind into the housing is provided.

Optionally, the elements of the hydraulic system which are external to the housing fit within the envelope of the external wind focussing rim.

In this way the hydraulic systems are protected from the force of the wind. A further aspect of the present invention provides a modular wind engine comprising two or more wind engines. Each of the two or more wind engines corresponds to a wind engine as described herein. The two or more wind engines may be arranged in an array.

The two or more wind engines may be connected to one or more converters. Each of the two or more wind engines may be connected to the other wind engines via the hydraulic system.

This modular system will enable the isolation of one of the two or more wind engines that needs maintenance whilst the remaining wind engines continue to work.

In this way maintenance can be completed in a very cost effective and safe way whilst minimising downtime, potentially to zero.

This system provides a method of tailoring the modular wind engine to the specific needs of a site which is simple and cost effective. Scaling the modular wind engine requires only to plug in another wind engine. By contrast, scaling HAWTs requires precision engineering and very high costs to produce huge, precisely shaped blades.

In some embodiments the first piston assembly has no more than one piston. In some embodiments the first piston assembly comprises a pair of pistons. Optionally there are two or more pistons, for example there are exactly two pistons.

In some embodiments the second piston assembly has no more than one piston. In some embodiments the second piston assembly comprises a pair of pistons. Optionally there are two or more pistons, for example there are exactly two pistons.

In some embodiments the hydraulic loop contains a converter for converting the pressure differential into useable work.

Optionally, the converter may be generator configured to convert the pressure differential into mechanical energy. Optionally, this mechanical energy may then be converted into electrical energy.

Alternatively, the pressure differential itself may form a usable output, for example it may be utilised by a desalination converter which contains a semi-permeable membrane and uses the pressure differential in a reverse osmosis process to purify water.

When brine is placed in a semi-permeable membrane under pressure water molecules are pushed through the membrane and leave any impurities within the membrane. The pressure required to push the water through the membrane can be provided by the pressure differential generated by the wind engine of the present invention.

In some embodiments the converter is a hydraulic generator or hydraulic motor. Several non-specialist, commercially available hydraulic motors and generators can be linked to the hydraulic system to cost effectively convert pressure into electricity.

Preferably the hydraulic generator comprises a variable displacement motor. In this way constant frequency electricity output can be obtained.

In traditional variable frequency horizontal axis wind turbines (HAWT) power electronics are required to control and convert the electricity generated (i.e. so it is grid-compatible). The power electronics systems add a major additional cost and reduce the efficiency of the wind turbines.

The wind engine of the present invention allows the collection of energy from the wind to be de-coupled from the generating frequency that the turbine produces through the use of variable displacement hydraulic motors connected to generators. The variable displacement motors are used to deliver a constant frequency of rotation under variable pressure environments, this constant frequency of rotation delivers grid compatible frequency, negating the need for power conversion electronics.

In some embodiments, the converter comprises a plurality of hydraulic motors. Preferably, the converter may comprise a plurality of variable displacement hydraulic motors. Each of the plurality of hydraulic motors may be of varying sizes and capacities.

Optionally, the converter further comprises at least one generator wherein the plurality of hydraulic motors are coupled to the at least one generator.

It may be that there are a plurality of generators. Optionally, each hydraulic motor is coupled to a different one of the plurality of generators. Each of the plurality of generators may be of varying sizes and capacities.

Optionally, when there are a plurality of hydraulic motors they are connected to a modular wind engine comprising two or more wind engines as described herein. Each wind engine may be connected to a different one of the plurality of hydraulic motors. Optionally, each wind engine is connected to all of the hydraulic motors via the hydraulic system.

In this way the wind engine can adapt to maximise the amount of energy that is generated for a given wind speed. This may be achieved through opening hydraulic valves to more hydraulic motors in higher winds, and by closing hydraulic valves thereby isolating one or more hydraulic motors in lower winds.

In the case where a modular wind engine comprising two or more wind engines is present, this may be achieved by shutting down one or more of the wind engines in lower wind conditions or by isolating one or more of the hydraulic motors or generators in lower wind conditions such that all of the wind engines continue to operate. A plurality of hydraulic motors allows the pressure within the hydraulic system to be managed to generate the maximum amount of energy, for example electricity. Increasing the number of hydraulic motors allows the wind engine to convert more energy, for example to generate more electricity, and reduces the pressure within the hydraulic loop. Reducing the number of hydraulic motors concentrates the pressure to act only on the remaining hydraulic motors and therefore allows the remaining motor(s) to continue to generate energy, for example electricity, at peak efficiency.

In the case where the converter comprises a plurality of variable displacement motors each variable displacement motor has a minimum operating pressure at which it can deliver constant, grid compatible frequency. If the pressure differential generated drops below this pressure then the motor will cease to operate. By the use of hydraulic valves (as discussed above) the wind engine can adapt to changing wind conditions by isolating or connecting variable displacement motors to the system.

In some embodiments the converter is a series of variable displacement motors.

The use of a series of variable displacement hydraulic motors ensures a low cut-in wind speed (the minimum wind speed in which electricity can be generated). This is achieved by connecting, for example, only one of the variable displacement motors at very low wind speeds. This means that the correspondingly low pressure differential generated is sufficient to drive the one connected variable displacement motor. In higher wind speeds more variable displacement motors can be connected to the hydraulic system.

The use of a series of variable displacement hydraulic motors allows some motors to be shut off from the hydraulic system for maintenance without shutting down the wind engine system. This allows the wind engine to continuously produce electricity.

In some embodiments each piston of the first piston assembly and the second piston assembly is connected to the hydraulic loop by an inflow pipe and an outflow pipe. Each inflow pipe and outflow pipe contains a one way valve. The first piston assembly is only hydraulically coupled to the second piston assembly via the converter.

In some embodiments the wind engine further comprises a yaw system. The yaw system comprises a rotating means and a brake. Optionally, the rotating means may comprise a bearing and a drive system.

Optionally, the yaw system has a control system. The control system processes signals from the wind sensor and controls the rotating means and brake. In this way the yaw system is an active yaw system.

Preferably, the yaw system is an electric motor controlled via control system with a wind direction sensor.

In some embodiments the hydraulic loop has a low pressure portion and a high pressure portion.

The high pressure portion is connected to the pistons via the outflow pipe. The low pressure portion is connected to the pistons via the inflow pipe.

In some embodiments the one way valve in the inflow pipe is configured to allow hydraulic fluid to flow from the low pressure portion into the piston.

In some embodiments the one way valve in the outflow pipe is configured to allow the hydraulic fluid to flow from the piston into the high pressure portion.

When one of the first wind catching surface and the second wind catching surface is closed, pressure from the wind is exerted on the wind catching surface resulting in movement of the wind catching surface within the housing along the elongate axis of the housing. This movement of the wind catching surface causes one or more of the pistons of the piston assembly to which it is mechanically coupled to compress.

Compression of the piston(s) of the piston assembly increases the hydraulic pressure in the piston chamber. The increased pressure in the piston chamber keeps the one way valve to the low pressure portion closed and hydraulic fluid is forced out of the piston chamber into the high pressure portion.

Since the first and second wind catching surface open and close in a reciprocal fashion, the other of the first wind catching surface and the second wind catching surface is open. There will be a lower, possibly significantly lower or negligible wind pressure acting upon this open wind catching surface. The pressure differential in the hydraulic system (generated by the closed wind catching surface) opens the one way valve from the low pressure loop into the piston chamber to which it is mechanically coupled. Hydraulic fluid flows into the piston chamber causing the piston to extend and moving the wind catching surface.

It may be that the high pressure portion is connected to the low pressure portion via the converter. For example, the converter may be a motor wherein the high pressure portion may feed into the motor and the low pressure portion may flow out of the motor. In this way the motor can convert the pressure differential between the high pressure portion and the low pressure portion created by the wind force (as outlined above) into useable work. It may be that the converter also comprises a generator. The motor is connected to the generator and converts the pressure differential into electricity via kinetic energy.

Further optional features of the invention are set out below.

Brief Description of the Drawings

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

Figure 1 shows a perspective view of a wind engine of the present invention.

Figure 2 shows a perspective view of a wind engine of the present invention.

Figure 3 shows a schematic of the hydraulic system of a wind engine of the present invention.

Figure 4 shows a schematic of the hydraulic system of a wind engine of the present invention.

Figure 5 shows a front view of a mechanical iris.

Figure 6 shows a side view of a wind engine of the present invention.

Figure 7 shows an expanded view of a mechanical iris arrangement.

Figure 8 shows a side view of a wind engine of the present invention.

Figure 9 shows a front view of a wind engine of the present invention having a mechanical iris.

Figure 10 shows side view of a wind engine of the present invention.

Figure 11 shows a perspective view of a wind engine of the present invention having two housing units.

Detailed Description and Further Optional Features of the Invention

Figure 1 shows a perspective view of a wind engine 1 of the present invention. The wind engine has first wind catching surface 2 and a second wind catching surface 3. The first wind catching surface 2 is in the open configuration. The wind catching surface 3 is in the closed configuration.

The first and second wind catching surfaces 2, 3 are contained within a housing 7. The housing 7 has a tube of circular cross section 8.

The first wind catching surface 2 is connected to the piston assembly 4. The second wind catching surface 3 is connected to the piston assembly 5 via a cranked return rod 6. Piston assembly 4 is contracted and piston assembly 5 is expanded.

The piston assemblies 4 and 5 are connected to a hydraulic system.

In this way when the second wind catching surface 3 catches the wind it will move slidably within the housing 7 and drive the piston assembly 5 to its contracted position. This will create a pressure different in the hydraulic system which will drive the piston assembly 4 to its expanded state and cause the first wind catching surface to move slidably within the housing 7.

Figure 2 shows a perspective view of a wind engine 1 of the present invention. Figure 2 shows the configuration of the wind engine of Figure 1 after the wind catching surface 3 has caught the wind.

The wind engine has first wind catching surface 2 and a second wind catching surface 3.

The first wind catching surface 2 is in the closed configuration. The wind catching surface 3 is in the open configuration.

The first wind catching surface 2 is connected to the piston assembly 4. The second wind catching surface 3 is connected to the piston assembly 5 via a cranked return rod 6. Piston assembly 4 is expanded and piston assembly 5 is contracted.

The piston assemblies 4 and 5 are connected to a hydraulic system.

In this way when the first wind catching surface 2 catches the wind it will move slidably within the housing and drive the piston assembly 4 to its contracted position. This will create a pressure different in the hydraulic system which will drive the piston assembly 5 to its expanded state and cause the second wind catching surface 3 to move slidably within the housing. This movement will return the wind engine to the configuration outlined in Figure 1.

In this way the first wind catching surface and the second wind catching surface can be described as reciprocal.

Figure 3 shows a schematic of part of a hydraulic system of a wind engine of the present invention. The hydraulic system has two pistons 33, a low pressure portion 34 and a high pressure portion 35. A wind catching surface 32 is connected to the hydraulic system 31 via two pistons 33. A magnified view 36 of the piston 33, the low pressure portion and the high pressure portion is shown. The pistons 33 are connected to the low pressure portion 34 via a one way valve 37. The pistons 33 are also connected to a high pressure hydraulic loop 35 via a one way valve 38 oriented to allow hydraulic fluid to exit the cylinder only. The one way valve 37 is configured to allow hydraulic fluid to flow into the piston only. The one way valve 38 is configured to allow fluid out of the piston only.

In this way, when the wind catching surface 32 catches the wind and compresses the piston 33 the hydraulic fluid in the piston is compressed and the pressure increases. This fluid is forced out of the piston into the high pressure portion 35. This creates a pressure differential in the hydraulic system.

Each wind engine is made up of two reciprocal wind catching surface/piston arrangements. When the wind catching surface 32 is compressing the piston 33 the other (reciprocal) wind catching surface/piston arrangement is expanded due to the pressure differential in the hydraulic system.

Figure 4 shows a schematic of a wind engine of the present invention.

The wind engine 51 has a first wind catching surface 52 and a second wind catching surface 53. The first wind catching surface 52 is in the closed configuration. The wind catching surface 53 is in the open configuration.

The first wind catching surface 52 is connected to the piston assembly 54. The second wind catching surface 53 is connected to the piston assembly 55. Piston assembly 54 is expanded and piston assembly 55 is contracted.

The piston assemblies 54 and 55 are connected to a hydraulic system 56.

In this way the wind engine is made up of two reciprocal wind catching surface/piston arrangements.

The hydraulic system 56 has a low pressure portion 57 and a high pressure portion 58.

The piston assembly 54 is connected to the low pressure portion 57 via inflow pipes 59. The inflow pipes 59 contains a one way valve oriented to allow fluid to enter the cylinder only.

The piston assembly 54 is also connected to the high pressure portion 58 via outflows pipe 60. The outflow pipes 60 contains a one way valve oriented to allow hydraulic fluid to exit the cylinder only.

The piston assembly 55 is connected to the low pressure portion 57 via inflow pipes 61. The inflow pipes 61 contains a one way valve oriented to allow fluid to enter the cylinder only.

The piston assembly 55 is also connected to the high pressure portion 58 via outflow pipes 62. The outflow pipes 62 contains a one way valve oriented to allow hydraulic fluid to exit the cylinder only.

The high pressure portion and the low pressure portion are connected to a converter 66.

The converter comprises a motor 64 and a generator 65. The motor is connected to a generator 65. The motor 64 may be a variable displacement hydraulic motor.

The combination of one way valves mean that the piston assembly 54 and the piston assembly 55 are only hydraulically connected via the converter 66.

When the wind catching surface 52 (which is in the closed configuration) catches the wind it will move slidably within the housing 63 in the windward direction and drive the piston assembly 54 to its contracted position. The hydraulic fluid in the piston chambers of the piston assembly 54 is compressed and the pressure increases. This fluid is forced out of the piston assembly 54 via the outflow pipes 60 into the high pressure portion 58. This creates a pressure differential in the hydraulic system.

The pressure differential is such that the high pressure portion 58 has an increased pressure. The increased pressure in the high pressure portion 58 drives the motor 64. In the case where the motor 64 is a variable displacement motor the motor is driven at a constant speed of rotation (within the operational pressure limits of the motor).

The motor 64 drives the generator 65 and moves hydraulic fluid into the low pressure portion 57.

In this way the wind engine of the present invention can convert energy from wind to electricity.

When the motor 64 moves hydraulic fluid into the low pressure portion 57 the pressure in the low pressure portion 57 increases. The increased pressure in the low pressure portion 57 forces hydraulic fluid into the piston assembly 55 via the inflow pipes 61. The piston assembly expands and moves the wind catching surface 53 slidably within the housing 63 in the leeward direction.

Hydraulic fluid is prevented from moving from the low pressure portion 57 into the piston assembly 54 via the inflow pipe 59. The hydraulic fluid in the piston assembly 54 has an increased pressure as a result of the wind force on the wind catching surface 52. This increased pressure prevents the one way valve from the inflow pipe 59 being opened.

At the maximum compression of the piston assembly 54 the wind catching surface 52 is opened by a suitable mechanism. This removes the force of the wind from the wind catching surface 52. When the piston assembly 55 reaches maximum expansion the wind catching surface 53 is closed by a suitable mechanism.

The wind catching surfaces 52 and 53 are opened and closed in unison, with opposing movements, so that as the windward iris opens, the leeward iris closes and vice versa.

Subsequently, the wind acts on the closed wind catching surface 53 and repeats the process of converting the wind energy into electricity by creating a pressure differential as outlined above.

In this way the wind engine can continue to generate electricity whilst the wind catching surface 54 is returned to its ‘original’ position. The mode of operation of the wind catching surfaces 52 and 53 and their respective piston assemblies 54 and 55 can be described as reciprocal.

Figure 5 shows front view of a mechanical iris. Figure 5A shows the full mechanical iris. The mechanical iris has a plurality of leaves 72. Figure 5B shows a single leaf 72 for clarity.

Each leaf 72 comprises a leaf shape tapering towards the centre of the iris and a cogged semi-circular end 73 at the perimeter. The cogged semi-circular end 73 has a pivot point 74. The iris has a connector 75 for connecting the iris to a piston assembly.

The perimeter of the iris comprises an angled shroud support 76 on both windward and leeward sides of the iris, with a perimeter cog 77 contained within the shroud supports (see also figures 6 and 7). The perimeter of the iris is shown in more detail in Figure 5B.

The rotation of this perimeter cog 77 relative to the shroud support 76 and the leaves 72 results in the leaves rotating about their pivot point 74 and moving to the centre of the iris. The counter rotation of the perimeter cog 77 relative to the shroud supports 76 and the leaves 72 result in the iris leaves moving back towards the perimeter.

The leaves 72 are arranged to overlap each other so that the iris can open fully.

In this way the iris can be converted between the open configuration which allows fluid flow through the iris and the closed configuration which allows the wind to exert a force on the iris.

Figure 6 shows a sectional view of a mechanical iris along the line A-A’ of Figure 5.

The iris leaves must be sufficiently strong and rigid to withstand the pressure applied to them from high winds. If the material strength is not sufficient to ensure this, upstands or flanges may be added to the leeward leading edge or the trailing windward edge of the iris leaves to give added rigidity.

Figure 7 shows an expanded view of a mechanical iris arrangement. The expanded view 81 shows the connection between the iris and the hydraulic system. The iris leaves 72 are connected to a piston 82 via the connecter 75. The iris leaves 72 sit inside the support shroud 76. The support shroud also encompasses the perimeter cog 77.

In this way when a force is applied to the closed iris this force is transmitted via the support shroud 76 and the connector 75 to the piston 82. Similarly, when the piston it expanded (or contracted) due to a pressure differential in the hydraulic system to which the piston is attached the movement of the piston is transmitted to the iris via the connector 75 and the support shroud 76.

One method to control the opening and closing of the irises is via a controlled electrical motor. The motor may be rotatably connected between two splined shafts that are solidly connected to a single iris leaf. The two splined shafts may be arranged so that the rotation of the electrical motor invokes opposing rotations in the shafts. The connection to a single iris leaf ensures that the rotation of the shaft is transferred to the perimeter cog which then rotates all the iris leaves, to either open or close the iris. The counter rotation of the two splined shafts may provide that the opening and closing motion of both irises is synchronous. The electrical motor may be activated by sensors within the turbine structure. These sensors may direct the motor so that the irises are opened and closed at the fullest extent of their range of motion. This mechanism can also be utilised to partially open and close both irises in the event of damagingly high wind speeds.

Figure 8 shows a side view of a wind engine of the present invention. The housing 91 has a wind focussing rim 93 at each end. The piston assembly comprises a windward hydraulic cylinder 95 and a leeward hydraulic cylinder 96.

The windward hydraulic cylinder 95 and the leeward hydraulic cylinder 96 are offset. In this way the range of movement of the hydraulic cylinders can overlap.

The leeward hydraulic cylinder 96 is connected to the leeward iris 98 by a cranked return piece 94.

The windward hydraulic cylinder 95 and the leeward hydraulic cylinder 96 fit within the envelope of the external wind focussing rims 93.

In this way the hydraulic systems are protected from the force of the wind.

Yaw control of the turbine system can be achieved utilising an electric motor controlled via a wind direction sensor and control system.

Figure 9 shows a front view of a wind engine of the present invention. The wind engine has a mechanical iris 100 in the closed configuration.

Figure 10 shows a side view of a wind engine of the present invention. The housing 105 has a wind focussing rim 106 at each end.

Two hydraulic cylinders 107 and 108 are located on the outside of the housing 105. The two hydraulic cylinders 107 and 108 fit within the envelope of the external wind focussing rims 106.

In this way the hydraulic systems are protected from the force of the wind.

Figure 11 shows a perspective view of a wind engine of the present invention having two housing units 110.

Each of the two housing unit is mounted on a pole 111. In this way the housing 110 can be raised above ground level.

Each housing unit 110 may contain a single wind catching surface. The wind catching surface in one of the two housing units is the first wind catching surface and the wind catching surface in the other of the two housing units is the second wind catching surface.

In this way the two housing units act as a reciprocal pair.

Alternatively (not shown), each housing unit 110 may contain a first wind catching surface and a second wind catching surface. In this way each of the two housing units can operate independently as a wind engine of the present invention.

While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure.

For example, although many of the embodiments shown include two piston assemblies, each piston assembly comprising a pair of pistons, it is envisaged that each pair of pistons could be replaced by a single piston.

Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

All references referred to above are hereby incorporated by reference.

Claims

1. A wind engine comprising: a housing a first wind catching surface and a second wind catching surface, each wind catching surface: being slidably movable within the housing; and having an open configuration and a closed configuration, wherein when one wind catching surface is in the open configuration the other wind catching surface is in the closed configuration; a hydraulic system, including a first piston assembly and a second piston assembly, wherein the first piston assembly is mechanically coupled to the first wind catching surface; the second piston assembly is mechanically coupled to the second wind catching surface; and the first piston assembly and the second piston assembly are hydraulically coupled to one another to form a hydraulic loop; wherein when a wind force acts upon one of the first and second wind catching surfaces in its closed configuration it will cause the wind catching surface to move slidably within the housing, driving the respective coupled piston assembly which creates a pressure differential in the hydraulic loop; and wherein the resulting pressure differential drives the other piston assembly and the other of the first and second wind catching surface to which it is mechanically coupled.

2. The wind engine of claim one wherein one or more of the first wind catching surface and the second wind catching surface is a mechanical iris.

3. The wind engine of any one of the preceding claims wherein the housing comprises one tube within which both the first wind catching surface and the second wind catching surface are located and are slidably movable.

4. The wind engine of claims 1 or 2 wherein the housing comprises two tubes; and wherein the first wind catching surface is located within in one of the two tubes and the second wind catching surface is located within the other of the two tubes.

5. The wind engine of any one of the preceding claims wherein the first piston assembly comprises no more than one piston.

6. The wind engine of any one of the preceding claims wherein the second piston assembly comprises no more than one piston.

7. The wind engine of any one of claims 1 to 4 wherein the first piston assembly comprises a pair of pistons.

8. The wind engine of any one of the claims 1 to 4 or claim 7 wherein the second piston assembly comprises a pair of pistons.

9. The wind engine of any one of the preceding claims wherein the hydraulic loop contains a converter for converting the pressure differential into useable work.

10. The wind engine of claim 9 wherein the converter is a hydraulic generator.

11. The wind engine of claims 9 or 10 wherein each piston of the first piston assembly and the second piston assembly is connected to the hydraulic loop by an inflow pipe and an outflow pipe wherein each inflow pipe and outflow pipe contains a one way valve such that the first piston assembly is only hydraulically coupled to the second piston assembly via the converter.

12. The wind engine of any one of the preceding claims wherein the hydraulic loop has low pressure portion and high pressure portion.

13. The wind engine of claim 12 wherein the one way valve in the inflow pipe is configured to allow hydraulic fluid to flow from the low pressure portion into the piston.

14. The wind engine of claim 12 or 13 wherein the one way valve in the outflow pipe is configured to allow the hydraulic fluid to flow from the piston into the high pressure loop.

15. A modular wind engine comprising two or more wind engines, each of the two or more wind engines corresponding to a wind engine of any one of claims 1 to 14.

16. The modular wind engine of claim 15 wherein the two or more wind engines are arranged in an array.

17. The modular wind engine of one of claims 15 or 16 wherein the hydraulic system has a converter.

18. The modular wind engine of claim 17 wherein the converter comprises a plurality of hydraulic motors.

19. The modular wind engine of claim 18 wherein one or more of the plurality of hydraulic motors may be isolated.

20. The modular wind engine of any one of claims 17 or 19 wherein the converter further comprises at least one generator coupled to the plurality of hydraulic motors.

21. The modular wind engine of claim 20 wherein there are a plurality of generators.

22. The modular wind engine of claim 21 wherein each of the plurality of hydraulic motors is coupled to a different one of the plurality of generators.

23. The modular wind engine of claim 21 or 22 wherein one or more of the generators may be isolated.

24. The modular wind engine of any one of claims 18 to 23 wherein the hydraulic motors and, if present, the plurality of generators may be of varying sizes and capacities.

25. The modular wind engine of any one of claims 17 to 24 wherein each of the plurality of wind engines is connected to all of the plurality of hydraulic motors via the hydraulic system.

26. The modular wind engine of any one of claim 18 to 25 wherein at least one of the plurality of hydraulic motors is a variable displacement motor.

27. The modular wind engine of claim 26 wherein each of the plurality of hydraulic motors are variable displacement motors.

28. A wind engine substantially as herein described with reference to the description and figures.

29. A modular wind engine substantially as herein described with reference to the description and figures.