GB2206653A

GB2206653A - Vertical axis wind turbine

Info

Publication number: GB2206653A
Application number: GB08715991A
Authority: GB
Inventors: Vane Sutton-Vane
Original assignee: SUTTON VANE VANE
Current assignee: SUTTON VANE VANE
Priority date: 1987-07-07
Filing date: 1987-07-07
Publication date: 1989-01-11
Anticipated expiration: 2007-07-07
Also published as: GB2206653B; GB8715991D0

Abstract

The turbine rotor system 22 is mounted on a mast (14, Fig. 1) and each blade 33 of the system is fixedly mounted on the outer end of an arm 35 which at its other end is connected by a hinge 39 to a hub member 38 drivingly connected to a drive shaft (15), the axis of the hinge 39 in the plan view shown being inclined relative to the longitudinal axis of the arm 35, preferably by 45 degrees. The hinge 39 may also be tilted, at preferably 30 degrees, in a plane radial to the vertical axis. Ties (40) are connected between the hinge knuckles 37 and the blades 33 to prevent the bottom portions of the blades from bending due to centrifugal force. Provisions are made for stabilising the mast in its vertical position by guys (23, Figs. 1 & 7) and for pivoting the mast to a horizontal position (Figs. 2 & 8). <IMAGE>

Description

VERTICAL AXIS WIND TURBINE This invention relates to a vertical axis wind turbine.

According to the present invention there is provided a vertical axis wind turbine in which the or each blade is fixedly mounted at one end of an arm which is hinged to a hub member drivingly engaged with a drive shaft, the hinge axis in plan view being disposed at an angle relative to the longitudinal axis of the arm.

The hinge axis may be disposed at a compound angle, i.e. in plan view at an angle to the longitudinal axis of the arm and tilted in a plane radial to the vertical axis.

An embodiment of the invention will now be described, by way of an example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of the vertical axis wind turbine with the mast raised to a vertical position and the blades at rest, Figure 2 is a side elevation of the vertical axis wind turbine at a right angle to the view shown in Figure 1 with the mast lowered to a horizontal position, Figure 3 is a side elevation of the turbine rotor in a vertical position with the blades in the normal running position, Figure 4 is a partial plan view of the turbine rotor, Figure 5 is a more detailed side elevation of the turbine rotor showing only one of the blades, Figure 6 is a plan view of the turbine rotor showing only one of the blades, Figure 7 is a side elevation of the bottom part of the vertical axis wind turbine with the mast to a vertical position, Figure 8 is a side elevation at a right angle to that shown in Figure 7 with the mast lowered to a horizontal position, Figure 9 is a plan view showing the path of movement of a blade, Figure 10 is a view taken in the direction of arrow 10 of Figure 9 showing the path of movement of the blades, and Figure 11 is a view on a blade taken in the direction of arrow 11 of Figure 9 showing the path of movement of the blade.

The vertical axis wind turbine has a base 10 on which is mounted a tabernacle 11 provided with a bearing 12 pivotably supporting a channel frame 13 secured to a tubular main mast 14 through which extends a rotatable tubular drive shaft 15 which drives a step-up gear box 16 carried by the frame 13. The output shaft of the gear box 16 drives an electrical generator 17 via a drive shaft 18 and the frame 13 also carries ballast 19.

The mast 14 is connected-to an earth rod 20 by an earth cable 21. Provided at the upper end of the mast 14 is a turbine rotor system 22 which drives a short solid main shaft 15a which passes through a hub 38 and is supported in bearings in a removable inner tube 15b and attached to the drive shaft 15.

When the mast 14 is in the vertical position it is stayed by guys 23 one of which is tensioned by lever operated strainer 24 so as to allow detachment.

The mast 14 is raised and lowered by a removable block and tackle 25.

Secured to the frame 13 is a spreader 26 to which is connected a stay cable 27 which give extra stiffness to the mast 14 during raising and lowering.

When the mast 14 is struck and is horizontal it rests in a forked support 28 provided with a swivelling latch 29 which prevents the mast 14 rising if the rotor blades or other parts are removed from the rotor 22. A stop bar 30 is provided to prevent the mast 14 passing beyond the vertical when raised. A locking bar, not shown, clamps the ballast box 19 to the tabernacle 11 when the mast 14 is in the vertical position.

A control shaft 31 which is extended to form a lightning conductor 32 having an electrical path to the cable 21 is mounted on top of the hub 38 and rotates with the hub 38.

The turbine rotor system 22 is shown in greater detail in Figures 3 to 6 and comprises blades 33 of aerofoil cross-section each connected by a plate 34 to an arm 35 fixed to a spigot 36 provided on a knuckle 37 which is hinged to a central hub 38 which is connected the the main drive shaft 15.

Each knuckle 37 is hinged by a hinge pin 39 which in plan view is disposed at an angle of preferably 450 to the longitudinal axis of the respective arm 35 with the leading end of the hinge pin 39 directed inwardly of the hub 38 and the trailing end directed outwardly of the hub 38. The hub 38 is designed to allow the arms 35 to rise to preferably 450 above horizontal and to fall preferably 450 below horizontal. Due to the angled hinge pins 39 the blades 33 follow a curved and twisting path thus continuously altering their angle of attack as they move upwardly and downwardly. Such movement is illustrated in Figures 9 to 11. The optimum operating position for the blades 33 is when the arms 35 are horizontal.This motion gives suitable angles of 0 attack for starting with the arms 35 between 45 below horizontal and horizontal, and for governing when the arms 35 are between horizontal and 450 above horizontal. With increasing wind speed the speed of the shaft 15 increases steadily with the arms 35 rising from 450 below horizontal to horizontal. Above horizontal the speed of the shaft 15 increases more slowly and reaches a plateau with an arm angle of about 100 above horizontal. After that the arm angle continues to increase but shaft speed remains substantially constant. Even though the arms 35 have freedom to move between 450 above horizontal and 450 below horizontal, they may in use not use all of this movement. Due to the centre of gravity of the blade/arm the arms may not reach 450 above horizontal.

Alternatively, the hinge pins 39 can be located at a compound angle, i.e. with the hinge axis at substantially 450 in plan view as described, but tilted at preferably 30 in a plane radial to the vertical axis with the inboard end higher then the outboard end. This has the effect of altering the angles of attack of the blades 33 above and below the horizontal and gives slightly better starting.

To prevent the bottom portion of each blade 33 bending outwardly due to centrifugal force a tie 40 is connected at one end by a hook 41 to a point located above the foot of the blade 33 and at the other end to the associated hinge knuckle 37. In order to prevent the downwind blade 33 from threshing when the wind turbine is at rest and blade drop at low speed stall, all three blade arms 35 are interconnected by tubular control rods 42 extending between the arms 35 and a control spider 43 loosely fitting the vertical control shaft 31. The control rods 42 are provided with a forked and rotatable end connection 44 connected to a rotatable sleeve 45 provided on the arm 35. Secured to each sleeve 45 is an arm blade 46. It will be appreciated that the chords of the blade 46 due to the relative rotational movement between them and the arms 35 remain horizontal whatever the angle of the arms 35.

This motion imparted to the arms 35 and blades 46 means that the blades 46 when the arms 35 are about 50 or more below horizontal act as an inverted Vee rotor and when about 50 or more above horizontal act as a Vee rotor. Within these limits and under no-load conditions the rotor self rotates even with the blades 33 removed thus showing lack of parasitic drag.

When the turbine rotor 22 starts to rotate centrifugal force tends to make the feet of the blades 33 fly outward and upward and to assist this at low rotational speeds a coil raising spring 47 is provided which surrounds the control shaft 31 and extends between the hub 38 and the spider 43. In order to govern overspeed a governing coil spring 48 is provided which surrounds the control shaft 31 and extends between the spider 43 and an adjustable collar 49.

The springs 47 and 48 may be protected by a bellows type gaiter.

A brake disc 50 is provided on the underside of the hub 38 and a brake pad 51 is provided on a plunger 52 connected to a lever 53 pivoted to the mast 14, the lever 53 being connected to an operating cord 54 which extends to ground level for manual operation of the plunger 52. A second brake may be fitted to the drive shaft 15 at ground level.

The single blade ties 40 may be replaced by two parallel ties faired by flexible aerofoil cross-section shrouds.

It will be appreciated that the present invention can be applied to a single blade rotor and to rotors having two, three or more blades.

It will also be appreciated that the blade or blades can be attached to an arm or arms which extend across the vertical axis. With a single blade attachment to one end of such an arm a weight will be provided at the other end of the arm.

In place of the coil springs 47, 48 hydraulic systems can be provided for raising and governing.

The inboard ends of the arms 35 may be faired or provided with removable fixed pitch fairings.

The control rods 42 may have an aerofoil cross-section so as to act as an inverted Vee rotor and reduce parasitic drag.

The arms 35 may be pre-stressed by a terminal bar or bars located inside the tubular arms 35.

In an alternative blade arrangement a tie may also extend to the blade above the fixing to the arm 35 to provide a longer blade with two ties.

A bob-weight may be provided at the lower tie/arm junction to give self rising above the arm horizontal position.

Claims

1. A vertical axis wind turbine in which the or each blade of the turbine is fixedly mounted at one end of an arm whose other end is hinged to a hub member drivingly interconnected with a drive shaft, the hinge axis in plan view being inclined relative to the longitudinal axis of the arm.

2. A vertical axis wind turbine as claimed in claim 1, in which the leading end of the hinge pin of the hinge is in plan view directed inwardly of the hub member and the trailing end of the hinge pin is directed outwardly of the hub member.

3. A vertical axis wind turbine as claimed in claim 1 or claim 2, in which the hinge axis in plan view is inclined at an angle of 450 to the longitudinal axis of the arm.

4. A vertical axis wind turbine as claimed in any preceding claim, in which the hinge axis is also inclined relative to a plane radial to the vertical axis.

5. A vertical axis wind turbine as claimed in claim 4, in which the hinge axis is inclined at 300 relative to the radial plane with the leading end higher than the trailing end.

6. A vertical axis wind turbine as claimed in any preceding claim, in which said arm is fixed at said other end to a knuckle member forming part of said hinge.

7. A vertical axis wind turbine as claimed in any preceding claim, in which the arm is interconnected by a rod to a vertically movable spider mounted on a control shaft disposed on the axis of the drive shaft, said spider being acted upon by resilient means.

8. A vertical axis wind turbine as claimed in claim 7, in which one end of the rod is connected by a rotatable connector connected to a rotatable sleeve mounted on said arm, said sleeve being provided with a blade extending longitudinally of the arm.

9. A vertical axis wind turbine as claimed in any preceding claim, in which the bottom portion of the blade mounted at the outer end of the arm is connected by a tie member to the inner end of the arm.

10. A vertical axis wind turbine as claimed in any preceding claim, in which a disc brake pad is provided on the hub member which co-operates with a manually operated brake member.

11. A vertical axis wind turbine as claimed in any preceding claim, in which the hub member is mounted at the upper end of a mast pivotally mounted on a tabernacle, the mast in the vertical position being stayed by guys, and said mast being raised and lowered by a removable block and tackle.

12. A vertical axis wind turbine as claimed in claim 11, in which the mast is secured at its bottom end to a framework pivotally connected to the tabernacle, said drive shaft being drivingly connected through a gearbox to an electrical generator carried by said framework, and said framework carrying ballast.

13. A vertical axis wind turbine as claimed in any preceding claim, in which the or each blade mounted at one end of an arm is of aerofoil cross-section.

14. A vertical axis wind turbine as claimed in claim 9 and any one of claims 10 to 13 when dependent upon claim 9, in which the tie member is of aerofoil cross-section.

15. A vertical axis wind turine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.