WO1997037124A1

WO1997037124A1 - Wind power plant

Info

Publication number: WO1997037124A1
Application number: PCT/SE1997/000507
Authority: WO
Inventors: Anders SELLÉN
Original assignee: Sellen Anders
Priority date: 1996-04-03
Filing date: 1997-03-24
Publication date: 1997-10-09
Also published as: AU2415897A; SE505384C2; SE9601297D0; SE9601297L

Abstract

A wind power plant includes a boom (3), a vertical shaft (4) that supports the boom (3) midway between its ends for oscillatory slewing of the boom in the horizontal plane, a vertically-oriented blade (1, 2) at each end of the boom, wherein each blade can rotate around its vertical axis relative to the boom, coupling devices (7-10, 16, 17, 18, 19, 20; 51-54) that couple the blades (1, 2) together to provide a common rotational movement, wherein the coupling devices are adapted to maintain the blades (1, 2) at mutually opposite attack angles relative to the longitudinal direction of the boom (3), and driving devices (28, 29) that are adapted to force the coupling devices to reverse the attack angle of the blades when the boom (3) is at a selected angle relative to the direction of the wind. The coupling devices include two rotatable rings (10, 19) that are coaxial with the shaft (4). Each of the rings (10, 19) is rotatably coupled to one of the blades (1, 2). The driving device includes a transmission (16, 17, 18, 20; 51-54) between rings (10, 19) that turns the rings uniformly in mutually opposite directions. The transmission is provided with adjustable setting devices (40, 41; 50) that are arranged in a manner to establish a selected attack angle for the blades (1, 2) relative to the boom (3).

Description

WIND POWER PLANT

The invention relates to a wind power plant of the kind defined in the preamble of claim 1.

The inventive wind power plant is of the type that includes a boom which is supported between its ends by a vertical pillar for oscillatory pivotal movement in a horizontal plane. Mounted at each end of the boom is a vertically oriented blade or vane that can rotate about its vertical axis. A coupling device couples the blades to each other to provide common rotational movement and keeps the blades at opposite angles of attack relative to the direction of the boom. Also included is a device that enables the coupling device to reverse the attack angle of the blades relative to the longidutinal direction of the boom at a selected boom direction relative to the wind direction.

Wind power plants of this kind, although where the pivotal movement of the boom is in the vertical plane, are known from US-4 470 770 and US-4,595,336. It is know, however, to cause the boom to swing in the horizontal plane.

There is utilized in the inventive wind power plant a horizontal rotary boom movement such that the energy represented by the rotary or pivotal movement of the boom can be conducted down via a vertical shaft that supports the boom in a raised position that extends down to the ground, where the energy generated by the wind power plant can be led away from the lower part of the shaft.

With regard to a wind power plant of this kind it is desirable to be able to adjust the angle of attack of the blades relative to the boom during operation. This makes it possible to limit the power that the wind exerts on the wind power plant, which is important at high wind velocities. Moreover, by adjusting the blade attack angle, it is possible to change the pivotal frequency of the boom. In particular, it is possible to maintain the pivotal movement of the boom at a substantially constant frequency if deemed desirable. One object of the invention is thus to provide a wind power plant that includes simple and robust devices or means for setting the blades at selectable attack angles relative to the longitudinal direction of the boom while the wind power plant is in operation.

This objective is achieved by means of a wind power plant according to the accompanying claim 1.

Embodiments of the wind power plant are set forth in the accompanying dependent claims.

In a wind power plant of the type set forth in the introductory paragraphs herein, the invention can be said to be characterized in that the coupling device includes two rotatable rings that are coaxial with the shaft carrying the boom; in that each of said rings is rotatably coupled to one of the blades; and in that the driving device includes a transmission coupled between the rings to rotate them correspondingly in opposite directions, wherein the drive device includes means for driving the transmission in order to reverse the attack angle of the blades when the boom has swung out through a selected angle relative to the direction of the wind.

The end positions of the transmission determine the attack angles of the blades relative to the longitudinal direction of the boom, wherein the blades suitably assume equal but opposite attack angles at their two end positions. The attack angles of the blades can be adjusted by varying the extent to which the rings are rotated by the transmission.

In one embodiment, a gearwheel-type transmission can be coupled between the two rings and a servomotor may be constructed to cause one of the rings to rotate. A sensor that senses the direction of the boom relative to the wind direction can then be arranged to activate the servomotor so as to reset the angle of the blades relative to the boom when the boom has rotated through a pre-determined angle relative to the direction of the wind or so as to maintain a desired rotational frequency of the boom. When the attack angle of the blades is reversed, a cycle is started whereby the boom swings back toward and past the wind direction to its other end position in which the attack angle of the blades is reversed once again.

According to another embodiment of the invention, the two rings can be coupled by means of a mechanical transmission that is carried by a wind- actuated rudder which is adapted to set itself in the direction of the wind. The boom can herewith be provided with a dogging means and one of the rings can be provided with abutment means that define the angular position of the boom relative to the wind direction at which the transmission is forced to reverse the attack angle of the blades. There may also be provided a setting means that will define the attack angle of the blades, with the aid of an abutment means. A spring means is preferably arranged to bias the transmission towards its end positions that define the attack angle of the blades. When the attack angle is reversed, the spring must therefore be compressed.

The invention will now be described with reference to an exemplifying embodiment thereof and also with reference to the accompanying drawings.

Fig. 1 shows schematically a side view of an inventive wind power plant.

Fig. 2 illustrates schematically wind power plant of Fig. 1 from above.

Fig. 3 is a perspective view of the wind power plant transmission mounted between the blades.

Fig. 4 shows the central parts of the transmission together with the control devices used to set the attack angle of the blades.

Fig. 5 shows schematically an alternative embodiment of the devices used to control the attack angle of the blades.

Figs. 1 and 2 show an oscillatory type wind power plant in which a first blade 1 and a second blade 2 are mounted respectively at each end of a horizontal boom 3 that is supported midway along its length by a vertical shaft 4. When the wind is blowing, the blades 1 , 2 force boom 3 to slew or pivot back and forth m a horizontal plane, wherewith the oscillatory motion is transferred via shaft 4, and wherewith the power generated by the shaft 4 as a result of its oscillating movement is received for further utilization.

The shaft 4 is journaled in a tower 5 that rests, for example, on the ground. Fig. 1 also shows a rudder 6 that is mounted in a manner to be able to rotate on the tower and that sets itself in the direction of the wind.

As will be evident from Fig.3, the blade 2 is mounted on the boom by means of a rotary bearing 7 and that the rotary bearing 7 supports a line pulley 8 which is coupled, via a line eyelet 9, to a ring 10 that is configured as a line pulley and that surrounds the shaft 4 essentially coaxially. Rods 9 are firmly connected to the pulley 8 and the ring 10 in such a way that their movements are transferred synchronously and without slippage.

The blade 1 is carried on the other end of boom 3 by a corresponding bearing 7 which, via a line pulley 8, is coupled via two further rods 9 to another ring 19 that is shaped as a line pulley and that is coaxial with ring 10, wherewith the power and motion transmitted between the respective blades and rings can be identical.

The rudder 6 carries struts 16 on opposite sides of shaft 4. Each of the struts 16 carries a bearing shaft 17, said shafts 17 being coaxially aligned. Each of the shafts 17 carries a slew link 18 which is coupled to respective rings 10, 19 at each of its ends by means of respective joints 20 so that the rings 10, 19 are coupled to carry out identical but opposite rotational movements about their axes.

The arrangement is preferably such that the shafts 17, bearings or journals 20 and the axle of the rings 10, 19 all lie in the same vertical plane, and such that the symmetry planes of the two blades coincide and form a right angle with the aforesaid vertical plane.

The blades 1, 2 will herewith define identical or opposite attack angles relative to the longitudinal direction of the boom 3. Pivotal or slewing movement of the boom 3 can be reversed by reversing the attack angle of the blades 1 , 2 relative to the direction of boom 3.

As shown in Fig. 4, the rmg 10 is carried by and permanently attached to a sleeve 34 which surrounds the shaft 4. The ring 19 surrounds the sleeve 34 and is axially displaceable relative thereto. A spring support ring 27 is permanently attached to the sleeve 34. A helical compression spring 36 is located between the ring 27 and the ring 19. A setting device 40 can be mounted in a fixed position on a tower that surrounds shaft 4. The setting device 40 may comprise an hydraulic cylinder whose piston 41 acts on the spring ring 27 thereby displacing sleeve 34 upwards to a position that is at a certain distance from the upper end limit of the sleeve 34. The upper end limit of the sleeve 34 is defined by virtue of the links 18 being vertical. The force exerted by the spring 36 drives the ring 19 towards the upper ring 10, wherein the links 18, while being tilted in opposite directions, turn the rings 10, 19 in mutually opposite directions, wherein the angles through which the rings 10, 19 rotate will be equally as large with respect to the direction of the wind.

Fig. 4 shows that spring 36 is arranged to drive the rings 10, 19 together so that the blades will be caused to assume the attack angle relative to boom 3 defined by the setting means 40.

The blades 1, 2 can be given a greater angle of attack, by causing the piston 41 of the setting means 40 of the Fig. 4 embodiment to move down toward a bottom position. The attack angle of blades 1, 2 will be zero, when the piston 41 of the setting means 40 moves up so as to cause the ring 10 to turn the links 18 to vertical positions.

As will be evident from Fig. 4, the boom 3, or rather the shaft 4, carries a dogging means 28 that can move between two abutment means 29 on the ring 10. When the dogging means 28 strikes one of the stops 29,the rings 10, 19 are turned in mutually opposite directions via the links 18, wherein the ring 19 unloads the spring 36 and the attack angle of the blades is reversed, whereupon the boom 3 is exposed to reversing forces that cause the boom to slew back towards and past the wind direction. Figure 5 shows an alternative construction in which the rings 10 and 19 are coupled by means of a gearwheel transmission that imparts to rings 10, 19 opposite angular movements around their axis. A control motor can then drive the transmission in such a way that rings 10, 19 will assume definite selected mutual angular positions which, as in the earlier case, define the attack angles of the blades 1 , 2 relative to the boom 3. The rotary motion of respective rings 10,19 is suitably centred relative to the longitudinal direction of the boom. The wind direction can be sensed by a wind-direction sensor which, in turn, is arranged to control the motor 50 so that it can reverse the attack angles of blades 1, 2 when the boom 3 is at a selected angular distance from the direction of the wind.

By controlling the regulatable parameters so that the frequency of oscillation of the boom is kept essentially constant, the air resistance of the wind power plant will automatically be reduced as wind velocities rise.

Claims

1. Wind power plant that includes a boom (3), a vertical shaft (4) that supports the boom (3) midway between its ends for oscillatory slewing of the boom in the horizontal plane, a vertically-oriented blade (1, 2) at each end of the boom, wherein each blade can rotate around its vertical axis relative to the boom, coupling devices (7-10, 16, 17, 18, 19, 20; 51-54) that couple the blades (1,2) together to provide a common rotational movement, wherein the coupling devices are adapted to maintain the blades (1, 2) at mutually opposite attack angles relative to the longitudinal direction of the boom (3), and driving devices (28, 29) that are adapted to force the coupling device to reverse the attack angle of the blades when the boom (3) is at a selected angle relative to the direction of the wind, characterized in that the coupling devices include two rotatable rings (10, 19) that are coaxial with the shaft (4); in that each of the rings (10, 19) is rotatably coupled to one of the blades (1, 2); in that the driving device includes a transmission (16, 17, 18, 20; 51-54) between rings (10, 19) that turns the rings uniformly in mutually opposite directions; and in that the transmission is provided with adjustable setting devices (40, 41; 50) that are arranged in a manner to establish a selected attack angle for the blades (1, 2) relative to the boom (3).

2. A wind power plant according to Claim 1 , characterized in that the transmission includes a gearwheel transmission (51 -54) and in that the setting devices have connected thereto a drive motor (50) for mutual rotation of the rings (10, 19) and for temporary mutual locking of the blades at the preset attack angles.

3. Wind power plant in according to Claim 2, characterized in that the sensing devices are arranged to sense the boom direction relative to the direction of the wind, and in that the sensing devices are arranged to activate the motor (50) so that it reverses the attack angle of the blades at the selected boom directions relative to the wind direction.

4. A wind power plant according to Claim 1 , characterized in that the transmission includes links (18) that are coupled between the peripheries of rings (10, 19) at two diametrically opposed parts of the rings (10, 19), wherem the links (18) are carried at their midway points by a wind rudder that maintains the bisectrix of the rotary movement of the blades in the wind direction; in that a spring device (36) is adapted to bias the rings (10, 19) axially towards one another; and in that the dogging means (40, 41) is adapted to limit the relative rotational movement of the rings (10, 19).

5. Wind power plant according to Claim 4, characterized in that the dogging means (40, 41) is adapted to limit the axial displacement of one (10) of the rings from an end limit which corresponds to an attack angle of zero degrees for the blades.

6. A wind power plant according to Claims 1, 4 and 5, characterized by spring means for biassing the blades towards the attack angles of the blades defined by the setting means.