Abstract:
The invention relates to a vehicle ( 6 ) for transporting a wind turbine blade ( 5 ). The vehicle ( 6 ) comprises blade connection means ( 14 ) for connecting a first end ( 24 ) of the blade ( 5 ) to the vehicle ( 6 ), wherein the blade connection means ( 14 ) comprise tilting means ( 19 ) for elevating an opposite end ( 25 ) of the blade ( 5 ) and wherein a tip end ( 9 ) of the blade ( 5 ) is orientated in a forward direction of the vehicle ( 6 ). The invention further relates to a control system for controlling the tilting means ( 19 ) of a vehicle ( 6 ) and a method for transporting a wind turbine blade ( 5 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a vehicle for transporting a wind turbine blade, a control system and a method for transporting a wind turbine blade. 
       DESCRIPTION OF THE RELATED ART 
       [0002]    A wind turbine known in the art comprises a tapered wind turbine tower and a wind turbine nacelle positioned on top of the tower. A wind turbine rotor with a number of wind turbine blades is connected to the nacelle through a low speed shaft, which extends out of the nacelle front as illustrated on  FIG. 1 . 
         [0003]    Modern wind turbines are constantly optimize and redesigned to increase the power output and an obvious way to increase the output is to increase the size of the wind turbine. But the bigger the different parts of the wind turbine are, the more difficult they are to transport—especially on smaller roads—and the bigger the wind turbines are, the more remote they have to be sited. 
         [0004]    This is of course a problem and particularly regarding the wind turbine blades this problem is pronounced, in that unlike e.g. the tower, the blades can not be divided into sections during transport and then assembled at the erection site without it affecting their efficiency and/or flexibility. 
         [0005]    One way of solving the problem of transporting long wind turbine blades on relatively small roads or in difficult terrain, is disclosed in International patent application No WO 2006/000230. This application discloses a method for transporting blades, where the blade is suspended in both ends between a tractive vehicle and a non-tractive vehicle. Both the tractive vehicle and the non-tractive vehicle comprise means for height adjusting the blade, hereby making it possible to raise the blade over e.g. small road signs when going through a road bend and lowering the blade e.g. when going under a bridge. But because the height adjusting can only be done within a limited range, this method will only work when passing minor obstacles. If the obstacles e.g. in a road bend are large trees, crags or houses or if the terrain is very undulating, this method will soon meet its limitations. 
         [0006]    It is therefore also known in the art to use helicopters to transport the blades, when the roads or the terrain makes is impossible to transport them otherwise. But a helicopter large enough to lift and transport e.g. a 50 m long wind turbine blade is very expensive and the risk of the blade or personnel being damaged during landing or takeoff is significant. 
         [0007]    From JP 2004-243805 it is known to transport elongated devices by connecting one end of the device to the back of a truck and make the other end extend freely backward. The device can then be tilted to elevate the free end of the device when the vehicle passes corners. However to ensure that the vehicle does not tilt under the influence of the weight of the device the vehicle either has to be long or heavy which in both cases is disadvantageous. 
         [0008]    An object of the invention is to provide for a technique for transporting wind turbine blades without the above mentioned disadvantages. 
         [0009]    Especially it is an object of the invention to provide for an advantageous technique for transporting wind turbine blades in terrain, which is difficult to pass. 
       THE INVENTION 
       [0010]    The invention provides for a vehicle for transporting a wind turbine blade. The vehicle comprises blade connection means for connecting a first end of the blade to the vehicle, wherein the blade connection means comprise tilting means for elevating an opposite end of the blade and wherein a tip end of the blade is orientated in a forward direction of said vehicle. 
         [0011]    When transporting e.g. an 50 meter long and 20 ton heavy wind turbine blade, it is of course advantageous to keep the blade as close to the ground as possible, both to keep the blades centre of gravity as close to the ground as possible to ensure stability but also to ensure, that the blade can pass under bridges, high-voltage wires and the like. But a long wind turbine blade transported close to and approximately parallel with the ground can be virtually impossible to negotiate through a narrow curve on the road, particularly if there are obstacles such as rocks, houses, trees or other on one or both sides of the curve. It is therefore advantageous to provide a blade transporting vehicle with means for tilting the blade, in that when the blade is tilted—making it extend in an angle e.g. of 45° into the air—the length of the blade projected onto the ground is reduced and most of the blade is raised so high that it can pass over the obstacles. 
         [0012]    The unsuspended end of the blade can then be lowered again after passing the obstacle to increase the stability of the vehicle. 
         [0013]    Furthermore by orientating the tip end of the blade in the forward direction of the vehicle the blade can be arranged to extend beyond a truck propelling the vehicle hereby reducing the total length of the vehicle. Furthermore it is easier to negotiate a difficult turn when the tip is pointing forward, in that is easier to track the tip position when it is pointing in the direction of travel and because the path of the tip then substantially always will be the same as the vehicles i.e. the “obstacle-free” road ahead. 
         [0014]    It should be emphasized that by the term “a forward direction of said vehicle” is to be understood the front end of the vehicle or in other words the direction of the normal direction of travel when the vehicle is travelling forward straight ahead. 
         [0015]    In an aspect of the invention, said first end is a root end of said blade and said opposite end is a tip end of said blade. 
         [0016]    The blade is—when mounted on a wind turbine—attached at the root of the blade, making the tip of the blade extend freely outwards and the blade is therefore designed to withstand the strain of being suspended in only the root end of the blade. It is therefore advantageous to connect the root end of the blade to the blade connection means and elevate the free tip end of the blade. 
         [0017]    In an aspect of the invention, said tilting means is capable of tilting said blade in an angle of between 0° and 90°, preferably between 0 and 70°, and most preferred between 0 and 50°. 
         [0018]    If the tilting angle of the blade is too little, the blade will not be able to pass high obstacles and if the angle is too big the tilting means could be difficult to design and expensive to manufacture and the stability of the vehicle could be severely compromised. The present angle ranges therefore represents an advantageous relation between functionality, economy and stability. 
         [0019]    In an aspect of the invention, said vehicle comprises levelling means. 
         [0020]    A relatively small bump in the ground can potentially have a great effect on a long blade extending unsupported e.g. 45° into the air and if the vehicles (including the blade) centre of gravity at any time is moved outside the area on which the vehicle is supported on the ground the vehicle will overturn. It is therefore advantageous to provide the vehicle with levelling means, which at least to a certain degree can compensate for irregularities of the surface of the ground. 
         [0021]    In an aspect of the invention, said vehicle is self-propelled. 
         [0022]    Hereby is archived an advantageous embodiment of the invention 
         [0023]    In an aspect of the invention, said vehicle comprises steering means for steering said vehicle. 
         [0024]    Hereby is archived a further advantageous embodiment of the invention 
         [0025]    In an aspect of the invention, said blade connection means comprise means for attaching said blade by means of a mounting flange at the root end of said blade. 
         [0026]    The mounting flange of the blade is designed to transfer the tremendous torque that the wind-load on the blade creates, besides being able to carry the weight of the entire blade. It is therefore advantageous to make the blade connection means comprise means for attaching the blade at the mounting flange. 
         [0027]    In an aspect of the invention, said blade is connected to said blade connection means by way of a plurality of bolts. 
         [0028]    The mounting flange of the blade is on most modern wind turbines provided a multitude of threaded sockets embedded in the blade structure for use when mounting the blade on the wind turbine hub by means of bolts. It is therefore advantageous to bolt the blade to the blade connection means. 
         [0029]    In an aspect of the invention, said blade connection means comprise means for attaching said blade with a pressure side or a leeward side of said blade facing down. 
         [0030]    A vehicle according to the invention would by nature be longer than it would be wide. A wind turbine blade is by nature far more flexible in the direction between the pressure side and the leeward side, than it is in the direction between the leading edge and the trailing edge. It is therefore advantageous to make the pressure side or the leeward side of blade face down, particularly when transporting the blade in an erected position, in that the direction where the blade is most flexible and thereby most instable is then the same direction as the direction where the vehicle has its larges extend and thereby is the most stable. 
         [0031]    In an aspect of the invention, said tilting means comprise one or more tilting actuators such as one or more hydraulic cylinders, which is advantageous, in that tilting actuators and hydraulic cylinders in particular are relatively simple, inexpensive and well proven means for tilting large objects such as wind turbine blades. 
         [0032]    In an aspect of the invention, the centre of rotation of said tilting means are placed at said first end of said blade. 
         [0033]    If the centre of rotation of the tilting means are placed to far up the blade the vehicle would have to be relatively high (and thereby more expensive and unstable), in that the first end of the blade would move downwards if the opposite end was elevated. If the centre of rotation was placed above, bellow or behind the first end of the blade the design of the vehicle or the vehicles load carrying structure would have to be relatively complex a therefore more expensive. It is therefore advantageous to place the tilting means centre of rotation at or at least in close proximity of the first end of the blade. 
         [0034]    The invention further provides for a control system for controlling the tilting means of a vehicle according to any of claims  1  to  11 , wherein said tilting means are controlled in response to sensor inputs from said vehicle. 
         [0035]    A vehicle comprising a very long wind turbine blade being only suspended in one end and the free end of the blade extending e.g. 45° into the air, could under certain circumstances be very difficult to control, particularly if the blade starts to vibrate close to its own natural frequency. It could therefore be advantageous to provide the vehicle with a control system, which automatically and on the basis of one or more sensor inputs from sensors on the blade or on the vehicle, could control the tilting means e.g. by providing countermotion to dampen vibrations in the blade or even oscillations of the entire vehicle. 
         [0036]    Even further the invention provides for a method for transporting a wind turbine blade on a vehicle according to any of claims  1  to  11 . The method comprises the steps of
       connecting a first end of the blade to said vehicle by blade connection means, and   elevating an opposite end of the blade by tilting means of the blade connection means.       
 
         [0039]    By connecting one end of the blade to blade connection means and then elevate the other unsuspended end of the blade by way of tilting means comprised by and acting on the blade connection means is advantageous, in that it hereby is possible to transport blades in undulating terrain and through relatively sharp turns. 
     
    
     
       FIGURES 
         [0040]    The invention will be described in the following with reference to the figures in which 
           [0041]      FIG. 1  illustrates a large modern wind turbine known in the art, as seen from the front, 
           [0042]      FIG. 2  illustrates a wind turbine blade, as seen from the front, 
           [0043]      FIG. 3  illustrates an embodiment of a vehicle comprising a wind turbine blade in a substantially horizontal position, as seen from the side, 
           [0044]      FIG. 4  illustrates the same embodiment of a vehicle as illustrated in  FIG. 3  comprising a wind turbine blade in a tilted position, as seen from the side, 
           [0045]      FIG. 5  illustrates an embodiment of a vehicle, as seen from the top, 
           [0046]      FIG. 6  illustrates an embodiment of a vehicle, as seen from bellow, 
           [0047]      FIG. 7  illustrates an embodiment of a vehicle comprising a truck pulling a transporter mounted with a blade in a raised position, as seen from the side, 
           [0048]      FIG. 8  illustrates an embodiment of a vehicle comprising a truck pulling a transporter mounted with a blade in a substantially horizontal position, as seen from the side, and 
           [0049]      FIG. 9  illustrates an embodiment of a vehicle including another embodiment of blade connection means and tilting means, as seen from the side. 
       
    
    
     DETAILED DESCRIPTION 
       [0050]      FIG. 1  illustrates a wind turbine  1  known in the art, comprising a tapered tower  2 , which is subdivided into a number of tower sections. A wind turbine nacelle  3  is positioned on top of the tower  2 . 
         [0051]    The wind turbine rotor  4 , comprising a number of wind turbine blades  5 , is connected to the nacelle  3  through the low speed shaft which extends out of the nacelle  3  front. 
         [0052]      FIG. 2  illustrates a wind turbine blade  5 , as seen from the front. The wind turbine blade  5  comprises a leading edge  7 , a trailing edge  8 , a tip end  9  and a root end  10 . The two sides  20 ,  21  of the blade  5 , which extends between the leading edge  7  and the trailing edge  8 , are usually referred to as the leeward side  20  and the pressure side  21 . In this embodiment the pressure side  21  is the visible side. 
         [0053]    The blade  5  is typically hollow, except for one or more strengthening members extending substantially the entire length of the blade  5 . A wind turbine blade  5  known in the art is typically made of a glass fibre and resin composite reinforced by carbon fibre, carbon fibre reinforced wood or a combination hereof. 
         [0054]    The root  10  of the blade is typically provided with a mounting flange  11  comprising a number of embedded threaded sockets for attaching the blade  5  to the rotor hub by means of bolts. 
         [0055]    The arrow indicates the direction of rotation during normal operation when the blade  5  is mounted on a wind turbine  1 . The length L of the blade  5  is on traditional modern wind turbine blades  5  between 30 meters and 60 meters and the weight is between 8 tons and 20 tons. 
         [0056]      FIG. 3  illustrates an embodiment of a vehicle  6  comprising a wind turbine blade  5  in a substantially horizontal position, as seen from the side. 
         [0057]    In this embodiment of the invention the first end  24  of a blade  5  is attached to a vehicle  6  in form of a self-propelled transporter  12  by connecting the mounting flange  11  at the root end  10  of the blade  5  to blade connection means  14  by means of bolts (not shown). 
         [0058]    In this embodiment the blade connection means  14  comprise a connection frame  15  comprising a number of holes  28  corresponding to the threaded sockets embedded in the mounting flange  11  of the blade  5 . In another embodiment the blade connection means  14  could be formed as a plate or it could be designed more complexly e.g. in form of a frame comprising latticework. 
         [0059]    In this embodiment of the invention the blade  5  is only suspended by the connection frame  15  on the blade connection means  14  but in another embodiment the vehicle could further comprise one or more supports (not shown) for supporting the blade  5  e.g. at the middle, when the blade  5 —as shown—is in substantially horizontal position. 
         [0060]    In this embodiment the blade is mounted with the pressure side  21  facing down and the leeward side  20  facing up but in another embodiment it could be the pressure side facing up or either the trailing edge  8  or the leading edge  7  could face upwards. 
         [0061]    In this embodiment of the invention the vehicle  6  is only provided with one blade  5 , but in another embodiment the vehicle  6  could comprise more blades  6  e.g. two blades  6  both attached at the root end  10  to connection means  14  comprising tilting means  19  on the vehicle  6  with the opposite ends  25  pointing in the same or opposite directions. 
         [0062]      FIG. 4  illustrates the same embodiment of a vehicle  6  as illustrated in  FIG. 3  comprising a wind turbine blade  5  in a tilted position, as seen from the side. 
         [0063]    The blade connection means  14  does in this embodiment comprise tilting means  19 , in that the connection frame  15  is rotatably mounted on the vehicles load carrying structure  16  providing a centre of rotation  18  at a rotary joint on each side of the connection frame  15  and in that one end of two tilting actuators  17  are pivotally connected to the vehicles load carrying structure  16  and the other end of the tilting actuators  17  are pivotally connected to the bottom of the connection frame  15 . 
         [0064]    To elevate one end  25  of a blade  5  by tilting means at the other end  24  of the blade  5  the tilting means have to be provided with a centre of rotation  18 . In this embodiment the centre of rotation is placed close to the middle of the root end  10  of the blade  5 , but in another embodiment the centre of rotation  18  could be placed differently such as further up the blade  5 , behind the blade  5  or bellow the blade  5 . 
         [0065]    In this embodiment the tilting actuators  17  are hydraulic cylinders but in another embodiment the tilting means  19  could comprise pneumatic cylinders, motor driven spindle actuators or the tilting of the blade  5  could be preformed by a tackle and/or a winch. 
         [0066]    When the tilting means  19  are activated, which in this case means that the hydraulic cylinders starts to retract, the connection means  14  with the attached blade  5  is tilted hereby elevating the opposite free unsuspended end  25  of the blade  5  and making the blade  5  extend in an angle A in relation to a substantially horizontal plane of the vehicle  6 . In this embodiment the blade  5  is tilted to an angle A of approximately 45° in relation to the blades  5  substantially horizontal position illustrated in  FIG. 3  but in another embodiment the blade could be raised to any angle A between 0° and 90°. 
         [0067]    In this embodiment of the invention the speed and the direction of the vehicle and the tilting angle A of the blade  5  is controlled manually by a person operating the vehicle  6 . In another embodiment the vehicle  6  could be provided with a control system replacing, assisting or overwriting this manual control at least under certain circumstances. E.g. if strain-gauges mounted on the blade  5 , pressure sensors in the hydraulic system of the tilting means  19  or distance sensors mounted on the vehicle detects that the blade  5  is vibrating to a degree, that the deflection of the blade  5  could damage the blade  5  or even tilt the entire vehicle  6 , the control system could automatically enforce countermotion in the tilting means to dampen the vibrations. 
         [0068]    Radars or other kinds of sensors connected to the control system could also reduce the speed or the direction of the vehicle  6  if the blade  5  or the vehicle  6  was approaching obstacles or the control system could ensure that the vehicle  6  could only move at a certain (low) maximum speed when the blade  5  is raised above a certain angle A. 
         [0069]      FIG. 5  illustrates an embodiment of a vehicle  6  without a blade  5  mounted, as seen from the top. 
         [0070]    In this embodiment the tilting means  19  comprise two tilting actuators  17  placed substantially symmetrical around a vertical centre plane of the vehicle  6  but in another embodiment the tilting actuators  17  could be placed differently and the tilting means  19  could comprise another number of tilting actuators  17  or the tilting actuators  17  could be replaced or supplemented by a tackle, a winch, one or more counterweights or the like. 
         [0071]    In this embodiment the majority of the vehicles load carrying structure  16  are formed as a latticework rigidly connected to a transporter  12 , which in this embodiment is self-propelled, but in another embodiment the structure  16  could be solid, it could be formed as parallel beams or it could be designed in another way ensuring that the structure  16  is capable of substantially rigidly carrying the load of the blade  5  and the structures  16  self-weight. 
         [0072]      FIG. 6  illustrates an embodiment of a vehicle  6 , as seen from bellow. 
         [0073]    In this embodiment of the invention the bottom part of the vehicle  6  is more or less a standard self-propelled heavy-duty transporter  12  with hydrostatic drive. The self-propelled transporter  12  comprises a number of individually driven and steered wheel sets  13 , which through electronic multi-way steering provides a steering angle of +/−110°. This steering is used in individual modules as well as in any large longitudinal or lateral combination, which besides the illustrated carrousel steering provides the steering modes of 90° crab steering, diagonal crab steering and of course normal straight driving. 
         [0074]    Furthermore, in this embodiment each of the wheel sets  13  are provided with hydraulic axle suspension which by means of pendular axles are interconnected to hydraulic support circuits. Within these support circuits an equal axle load is achieved. A hydraulic stroke of up to +/−300 mm enables compensation in the vehicles  6  longitudinal and lateral direction and therefore permits operation on uneven terrain as well as adjustment for extreme side tilt (leveling). 
         [0075]      FIG. 7  illustrates an embodiment of a vehicle  6  comprising a truck  22  pulling a transporter  12  mounted with a blade  5  in a raised position, as seen from the side. 
         [0076]    In this embodiment of the invention the transporter  12  is not provided with means for making it self-propelled and the transporter  12  is therefore connected to a standard truck  22  by means of a relatively long substantially rigid connection rod  23 . The truck  22  pulls the non-driven transporter  12  and when passing a sharp bend on the road the blade  5  can be tilted as illustrated hereby making possible to pass the bend, in that the substantially rigid connection rod  23  is pivotally joined to both the truck  22  and the transporter  12 . 
         [0077]    In another embodiment of the invention the connection rod  23  could also be a hauling rope, a flexible rod, a wagon or a carriage e.g. comprising additional wind turbine  1  equipment or it could e.g. be replaced by a further non-driven transporter  12  e.g. comprising a second blade  5  extending in the opposite direction. 
         [0078]      FIG. 8  illustrates an embodiment of a vehicle  6  comprising a truck  22  pulling a transporter  12  mounted with a blade  5  in a substantially horizontal position, as seen from the side. 
         [0079]    When the blade  5  is in its initial substantially horizontal position the blade  5  extends over the roof of the truck  22  to reduce the total length of the vehicle  6 , making it easier for the vehicle  6  to negotiate road turns. In this embodiment the free tip end  9  of the blade  5  is not connected to or in any way supported by or at the truck  22  to enable free relative horizontal (and to some degree also vertical movement) between the blade  5  and the truck  22 . 
         [0080]      FIG. 9  illustrates an embodiment of a vehicle  6  including another embodiment of blade connection means  14  and tilting means  19 , as seen from the side. 
         [0081]    In this embodiment of the invention the first end  24  of the blade  5 , which in this case is the root end  10 , is placed in a supporting cradle  26  of the connection means  14 . The cradle  26  being rotatably joined to a load carrying structure  16  of the vehicle  6 . Furthermore, a couple of straps are tied across the blade  5  to firmly secure the blade  5  to the connection means  14 . Tilting means  19  are provided in form of a hydraulic cylinder acting on the cradle  26 , hereby elevating the opposite free end  25  of the blade  5 . 
         [0082]    In this embodiment of the invention the vehicle  6  on which the blade  5  is attached is a self-propelled transporter  12  but in another embodiment the transporter  12  could be non-driven and pulled by a truck  22  as illustrated in  FIGS. 7 and 8 . 
         [0083]    The invention has been exemplified above with reference to specific examples of vehicles  6 , blade connection means  14  and tilting means  19  for use when transporting wind turbine blades  5 . However, it should be understood that the invention is not limited to the particular examples described above but may be designed and altered in a multitude of varieties within the scope of the invention as specified in the claims. 
       LIST 
       [0084]      1 . Wind turbine 
         2 . Tower 
       3 . Nacelle 
       4 . Rotor 
       5 . Blade 
       6 . Vehicle 
       [0085]      7 . Leading edge
   8 . Trailing edge
 
         9 . Tip end 
       10 . Root end 
       [0086]      11 . Mounting flange 
         12 . Transporter 
       13 . Wheel set 
       [0087]      14 . Blade connection means
   15 . Connection frame
   16 . Load carrying structure of vehicle
   17 . Tilting actuator
   18 . Centre of rotation
   19 . Tilting means
   20 . Leeward side
   21 . Pressure side
 
         22 . Truck 
       23 . Connection rod 
       24 . First end 
       25 . Opposite end 
       [0088]      26 . Supporting cradle 
         27 . Strap 
       28 . Hole 
       [0089]    L. Length of blade
 
A. Angle of blade