WIND TURBINE COMPRISING A PRESSURE RELIEF VALVE

The current invention refers to a wind turbine.

We already know wind turbines that are mainly made up of a screw with two or three propeller blades that are attached to a rotor shaft and that are driven under influence of wind power, to power a generator or suchlike.

A disadvantage of these wind turbines is that they are relatively limited in the generated electric power and furthermore, reach a relatively low output at low wind speeds.

Another disadvantage of the existing conventional wind turbines is that, in case the wind speed is too high, these wind turbines have to be stopped and secured in order to prevent that the connected generator would get overheated due to too big induction currents and/or that the mechanical transmission between the screw and the generator would break down under the influence of peak loads .

In order to offer a solution to this, a wind turbine was already developed of the type that is provided with a housing that contains two parallel walls that are connected to one another by a side wall in which an entry and exit are provided; and a rotor that is applied between the above- mentioned parallel walls and that contains a blade wheel, at which the radial distance between the blade wheel and the above-mentioned side wall reduces from the above-mentioned entry of the housing towards the above-mentioned exit.

Such a wind turbine is described in the Belgian patent n° 1.016.069, in the name of the same applicant. According to the

invention, an advantage of such a wind turbine is that an air current in such a wind turbine is accelerated from the entry towards the exit of the housing, as a result of which the rotation speed of the rotor, as well as the generated power, is relatively huge.

The current invention aims at delivering a wind turbine that is improved in various respects compared to such existing wind turbines as described in the above-mentioned BE 1.016.069.

To this end, the invention concerns a wind turbine of the above-mentioned type, at which, according to the characterizing feature of the invention, an opening lockable by means of a valve is provided in the above-mentioned side wall, at which this valve can at least be moved between a closed and an opened position.

According to the invention, the advantage of such an improved wind turbine consists of allowing to open the above-mentioned valve at high wind speeds, at which an amount of the air entering through the entry can escape and the pressure in the space between the blade wheel and the side wall drops, so damage to the wind turbine can be avoided.

According to a feature of preference of the invention, the wind turbine is provided with regulation means for adjusting the position of the above-mentioned valve, which regulation means include at least one pressure sensor, which is applied at the height of the above-mentioned entry or in the space between the side wall and the blade wheel and which is connected to a regulator that drives activation means, such as for example a servomotor, at which these activation means adjust the position of the valve in relation to the opening.

An advantage of this is that a continuous regulation of the position of the valve can be carried out, according to the pressure that is measured at the entry of the wind turbine or elsewhere in the space between the side wall and the blade wheel, so that it can be ensured that the wind turbine can also keep turning at an almost constant speed at variable wind speeds as well and consequently, an almost constant amount of energy is generated.

With the intention of showing the features according to the invention in a' better way, a construction form of preference of an improved wind turbine according to the invention is described hereafter as an example, with reference to the enclosed drawings, in which:

figure 1 schematically represents a cross section of a wind turbine according to the invention; figure 2 represents a section according to line II-II in figure 1; figure 3 represents a side-view of the part that is indicated in figure 1 with arrow F3.

In the figures 1 and 2, a wind turbine (1) , which mainly consists of a housing (2) in which a rotor (3) is applied, is represented schematically according to the invention.

In this case, the housing (2) consists of two parallel walls (4 and 5) that in this case are mutually connected with a cylinder-shaped side wall (6).

This side wall (6) is provided with an entry (7) and an exit (8), that each preferably stretch out over the entire distance

A between the above-mentioned walls (4 and 5) .

At the above-mentioned entry (7), a conductor (9) with an opening (10) is applied to the housing (2), which conductor

(9) consists of two plates (11 and 12) , of which, in this case, one is attached to the housing (2) by means of a hinge pin (13) .

The exit (8), which preferably is situated at a short distance of the entry (7), is provided with a conductor (14) of which the opening (15) is directed in the opposite or almost opposite way in relation to the opening (10) of the above- mentioned entry (7) .

Preferably, the above-mentioned walls (4 and 5) stretch out at both sides beyond the above-mentioned conductors (9 and 14) .

The rotor (3) consists of a freely rotating shaft (16), to which a blade wheel (17) is attached, that consists of two parallel plates (18 and 19) that are mutually connected by a cylinder-shaped inner wall (20) , of which the outer circumference is provided with fixed blades (21) that are mainly directed radially and that stretch out over the entire length L of the blade wheel (17), which length L is somewhat smaller than the above-mentioned distance A between the above- mentioned walls (4 and 5) of the housing (2) .

This rotor (3) has eccentric bearings in relation to housing

(2) in the walls (4 and 5) , at which the distance between the blade wheel (17) and the side wall (6) of the housing (2) reduces from the entry towards the exit (8) and at which the blades (21) almost touch the above-mentioned side wall (6) of the housing (2) near the exit (8) .

The shaft (16) of the rotor (3) is, as known, connected to a generator (22), which in this case is attached to the housing (2) .

Preferably, the wind turbine (1) is also provided with means that allow turning the entry of the housing (2) according to the wind direction W, which means (23) can, for example, consist of a conductor in the form of a rail (24) that forms a circular trace and of wheels (25) that are attached to the housing (2) and that are placed on the above-mentioned rail (24).

According to the invention, the use of such a rail (24) allows turning a relatively big wind turbine (1) according to the wind direction W, more specifically, a wind turbine (1) with a width and height in the order of size of a few metres.

According to the invention, at least one opening lockable by means of a valve is provided in the above-mentioned side wall (6) . In the example of the figures, three of such openings

(26) are provided in the wall (6), that are each lockable by means of a separate valve (27) in the form of a hatch because these valves (27) can at least be moved between a closed an opened position.

According to the invention, the improved wind turbine (1) preferably contains regulation means that are not represented in the figures for adjusting the position of the above- mentioned valves (27), which regulation means include at least one pressure sensor which is applied at the height of the above-mentioned entry (7) or in the space between the wall (6) and the rotor (3) and which is connected to a regulator that

controls activation means for adjusting the position of the respective valves (27) in relation to the openings (26).

According to a special feature of the invention, the above- mentioned conductor is provided with a regulation algorithm that compares the pressure value measured by the above- mentioned pressure sensor with a desired value or a certain preset pressure range and that can control the above-mentioned activation means in such a way that the measured pressure value at the entry (7) or in the space between the side wall (6) and the blade wheel (17) can be regulated according to the above-mentioned desired value or that this pressure value is kept within the above-mentioned preset pressure range.

In this case, the above-mentioned activation means are carried out in the form of a number of servomotors (28) that, for example, can be fed by one or more batteries and that are each built-in in a hinge (29) , with which each respective valve (27) is attached, allowing it to be hinged against the wall (6) of the wind turbine (1) .

According to a feature of preference of the invention, the wind turbine (1) is also provided with energizing means for driving the blade wheel (17) , which energizing means, as represented in figure 3, include at least one, and in this case two ventilating fans (30) that are placed on top of one another and that are attached at the height of the above- mentioned entry (7) and that are directed towards the blade wheel (17) .

In this case, the above-mentioned ventilating fans (30) are each powered by a separate electric motor (31) with an adjustable speed through a transmission (32), which , for

example, can consist of a chain transmission, a belt transmission, a gear wheel transmission or similar.

The motors (31) can, for example, be fed by means of the electricity that is generated by the above-mentioned generator (22) .

Each of the ventilating fans (30) is at least partly fixed into a cylinder-shaped shaft (33) , which is a conductor for the air that is blown to the blade wheel (17) .

Finally, the above-mentioned energizing means preferably include one or more, and in this case three, driving motors

(34) , which in this case are applied in the space between the wall (6) and the blade wheel (17), which driving motors (34) are set up in such a way that they can drive the blade wheel

(17) .

For this purpose, the above-mentioned driving motors (34) each energize a transmission mechanism (35) that can be switched in a first position, at which the blade wheel (17) is driven and in a second position at which the blade wheel (17) is not driven, which transmission mechanism (35) in this example includes a toothed wheel (36) that can work together with a toothing, which is provided over the outer circumference of the above-mentioned blade wheel (17) .

The above-mentioned transmission mechanism (35) is not limited to a toothed wheel transmission, however, according to the invention, it can be carried out in many other ways, such as, for example, in the form of a rotating rubber belt which can, in the first position of the transmission mechanism (35) , be

pressed against the outer circumference of the blade wheel (17), for driving this blade wheel (17).

According to the invention, the operation of the wind turbine (1) described above, is simple and goes as follows.

The above-mentioned conduction (9) at the entry (7) of the wind turbine (1) is placed in the wind, as a result of which an air current is led through the entry (7) into the housing (2) , which air current lets the blades (21) of the rotor (3) rotate in the sense R. Because the distance of the blades (21) to the side wall (6) of the housing (2) reduces from the entry (7) towards the exit (8), the air current between the different blades (21) , the walls (4 and 5) and the side wall (6) of the housing (2) is accelerated, which results in an acceleration of the rotation of the rotor (3) .

Finally, the air current leaves the wind turbine (1) through the exit (8), avoiding, with the aid of the conduction (14), that the air that leaves the wind turbine (1) disturbs the air current to the wind turbine (1) .

In case the wind speeds are getting too high, the air current that is conducted through the wind turbine (1) can be reduced by covering the above-mentioned opening (10) of the conduction

(9) at the entry (7) of the wind turbine (1) more or less with the help of the plate (12) that can be hinged.

It should be noted that the side wall (6) of the housing (2) can also be realized spiral shaped, with which the radius of the bend of the side wall (6) decreases from the entry (7) towards the exit (8), in a way that is equal to the rotation way R of the rotor (3) .

It should also be noted that it is not necessary to apply a blade wheel (17), at which the blades (21) are attached to the outer circumference of a cylinder-shaped inner wall (20) , but that it is also possible to attach the different blades (21) directly to the above-mentioned shaft (16) , dependent on the design of the wind turbine (1) .

According to the invention, the above-mentioned valves (27) can be opened at high wind speeds, as a result of which an amount of air entering through the entry (7) can escape and the pressure in the space between the blade wheel (17) and the side wall (6) decreases, so damage to the wind turbine (1) can be avoided.

For this purpose, the above-mentioned regulation means can be preferably used to adjust the position of the above-mentioned valves (27), taking a pressure measurement at the height of the above-mentioned entry (7) or elsewhere in the space between the side wall (6) and the blade wheel (17) into account.

Because of this, a continuous adjustment of the position of the valves (27) can be realized, so that it can be made sure that the wind turbine (1) also keeps turning at an almost constant speed in case of variable wind speeds and consequently, an almost constant amount of energy is generated.

In case there is little wind, the above-mentioned valves (17) are closed, so a maximal use of the available wind energy is obtained.

When the wind speed threatens to become too low and the wind turbine (1) threatens to come to a stop or to slow down, the above-mentioned energizing means can be activated, for example because the driving motors (34) are driven and the transmission mechanisms (35) are switched into their first position, all this in such a way that the toothed wheels (36) engage into a toothing on the outer circumference of the blade wheel (17) .

In order to avoid problems concerning the friction between the toothed wheels (36) and the toothing on the blade wheel (17), the teeth of these toothed wheels (36) and the toothing on the blade wheel (17) preferably show a rounded shape.

Furthermore, the above-mentioned ventilating fans (30) can be activated in case of little wind power, all this in such a way that an air current can be achieved.

The activation of the ventilating fans (30) as well as the adjustment in the first position of the transmission mechanisms (35) results in the fact that the blade wheel (17) can also keep turning at a relatively high and controlled speed at low wind speeds as well, as a result of which the generation of electric energy by means of the generator (22) remains guaranteed.

This electric energy can in its turn be used for driving the motors (31) and the driving motors (34) .

When the wind strength increases again, the transmission mechanisms (35) are adjusted into their second position so the toothed wheels (36) no longer drive the blade wheel (17) and the ventilating fans (30) are no longer driven either.

As represented in figure 2, the wind turbine (1) is preferably placed with its shaft (16) in a vertical position, even though a horizontal set-up is also possible.

The current invention is by no means limited to the execution forms described as an example and represented in the figures, however, an improved wind turbine according to the invention can be carried out in many shapes and measurements, without going out of the scope of the invention.

SUBSTITUESHEET(RULE26)