(19)
(11)EP 1 788 239 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
08.01.2014 Bulletin 2014/02

(21)Application number: 06124089.1

(22)Date of filing:  14.11.2006
(51)Int. Cl.: 
F03D 11/00  (2006.01)
F03D 11/02  (2006.01)

(54)

Rotor for a wind energy turbine and method for controlling the temperature inside a rotor hub

Rotor einer Windenergieanlage und Verfahren zur Temperaturkontrolle im Inneren der Rotornabe

Rotor d'une éolienne et procédé pour contrôler la température à l'intérieur du moyeu de rotor


(84)Designated Contracting States:
DE DK ES

(30)Priority: 18.11.2005 US 283162

(43)Date of publication of application:
23.05.2007 Bulletin 2007/21

(73)Proprietor: General Electric Company
Schenectady, NY 12345 (US)

(72)Inventor:
  • LUETZE, Henning
    48455, Bad Bentheim (DE)

(74)Representative: Bedford, Grant Richard 
GPO Europe GE International Inc. The Ark 201 Talgarth Road Hammersmith
London W6 8BJ
London W6 8BJ (GB)


(56)References cited: : 
EP-A1- 1 375 913
DE-A1- 19 644 355
DE-C- 842 330
JP-A- 2005 069 082
US-A1- 2005 242 233
DE-A1- 19 621 485
DE-A1- 19 802 574
JP-A- 2003 343 417
US-A- 2 701 696
US-B1- 6 676 122
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [0001] This invention relates generally to wind turbines, and more particularly to the control of the temperature inside a hub of a rotor of a wind energy turbine.

    [0002] Large modern type energy turbines include rotors having hubs which include several components such as a rotor blade actuator (pitch) drive which produce energy losses in the form of heat that increases the temperature inside the hub. In some types of wind energy turbines, the temperature inside the hub increases due to heat flow from components of the nacelle located close to the hub of the rotor. Due to the shaft of the rotor extending from the hub into the nacelle there is a relatively large opening between the hub and the nacelle where warm air from inside the nacelle can easily propagate into the hub. At higher ambient temperatures the above-identified two effects can lead to temperature levels inside the hub which are higher than the upper temperature limits tolerable for the components arranged in the hub.

    [0003] US 2005/0242233 discloses an anti-icing system for wind turbines.

    [0004] JP 2005 069 082 describes a temperature controller of a windmill.

    [0005] US 6,676,122 relates to a wind energy facility with a closed cooling circuit.

    [0006] In one aspect according to the present invention, a rotor for a wind energy turbine in accordance with appended claim 1 is provided.

    [0007] In another aspect of the present invention there is provided a method as defined in appended claim 2.

    [0008] Various aspects and embodiments of the present invention will now be described in connection with the accompanying drawings, in which:

    Fig. 1 shows a front view of a wind energy turbine schematically indicating the air flow inside the blades for cooling purposes of the hub.

    Fig. 2 is a schematic diagram of a first alternative for an air flow for temperature controlling purposes inside the hub.

    Fig. 3 shows a second alternative for an air flow for temperature controlling purposes inside the hub.



    [0009] In order to solve the problem of increased temperature inside a rotor hub of a wind energy turbine, by way of various embodiments of the present invention there is suggested an air flow means for causing air to flow from inside the hub out of the hub and into the inner space of the at least one rotor blade attached at its root to the hub. The inner space of the hub and the inner space of the at least one rotor blade are in fluid communication with each other at the root of the at least one rotor blade for the exchange of air between the inner spaces of the hub and blade. The air flowing from the hub into the at least one rotor blade exits the same to the outside thereof or may re-enter the hub after having flown through the inner space or at least a part of the inner space of the at least one rotor blade.

    [0010] In an active system the air flow means includes a fan arranged in the hub for blowing air from the hub into the at least one rotor blade. As an alternative, the fan is located inside the at least one rotor blade for sucking air from the hub into the at least one rotor blade.

    [0011] Modem rotor blades comprise an outer shell defining the inner space of the rotor blade. The outer shell includes a spar having two spar cabs located at opposite walls of the outer shell and connected by a supporting web or wall extending longitudinally through the rotor blade from a site close to the root to a site close to the tip of the rotor blade. The inner supporting web separates the inner space of the rotor blade into two half spaces which are in fluid communication with each other at the tip of the blade and wherein both half spaces at the root of the rotor blade are in fluid communication with the hub by way of two separate openings. In an active air flow means the fan is arranged, e.g. in the hub, in order to blow heated air through one of the two openings in the root of the rotor blade into the respective one half space. The air flows through this half space towards the tip of the rotor blade and, at the tip, into the other half space and back towards the hub. The air is cooled when it flows along the inner surface of the shell of the rotor blade so that heated air from inside the hub is cooled within the at least one rotor blade and is fed back as cooled air into the hub. In this active system the fan can also be arranged within one of the openings at the root of the rotor blade.

    [0012] Various embodiments of the invention can be used both for cooling the inner space of the hub at higher ambient temperatures but also for heating the interior of the hub during winter time. The rotor blades of a wind energy turbine hub may be heated up from solar radiation so that this heat can be used to cause warm air to flow out of the inner space of the at least one rotor blade into the hub. By this action, a temperature control inside the hub is performed to keep the temperature inside the hub more constantly and closer to e.g. the optimal design temperature of batteries or other operating components inside the hub which increases the lifetime of these components.

    Fig. 1 depicts a wind energy turbine 10 comprising a tower 12 and a nacelle rotatably supported by tower 12 as well as a rotor 16 rotatably supported by nacelle 14. Rotor 16 includes a central hub 18 and three rotor blades 20 mounted to hub 18. Each rotor blade 20 includes an outer tip 22 and an inner root 24 attached to hub 18. Dotted lines 26 schematically indicate an air flow out of hub 18 and through the inside of rotor blades 20 for controlling the temperature inside hub 18. The embodiment shown in Fig. 1 comprises a three blade rotor 16. However, the number of blades 20 of rotor 16 is not critical. Also it is not necessary that, for temperature controlling purposes inside hub 18, an air flow 26 has to be established through all rotor blades 20. Accordingly, various embodiments of the present invention also function in a one blade rotor or in a multiple blade rotor wherein an air flow is generated from hub 18 towards at least one of the rotor blades and through this at least one rotor blade 20.

    Fig. 2 shows a first alternative for an air flow means 28 arranged within hub 18 and creating a circulating air flow 26 from hub 18 through blade 20 and back to hub 18. This active air flow means 18 includes a motorized fan 30 arranged inside hub 18. Fan 30 can also be arranged within blade 20. Blade 20 typically includes an outer shell or wall 32 defining an inner space 34 which is divided into two half spaces 36, 38 by means of an inner supporting wall 40 for stiffening and stabilizing outer shell 32 of blade 20. Inner supporting wall 40 extends from root 24 of rotor blade 20 towards close to its tip 22 at which the two half spaces 36, 38 are in fluid communication with each other. At root 24 of blade 20 there are two separate openings, namely one inlet opening 42 and one outlet opening 44. Air to be temperature-controlled from inside hub 18 is blown by means of fan 30 out of hub 18 and into half space 36 through which the air flows in a longitudinal direction of rotor blade 20 through the same. At tip 22 the air enters the second half space 38 through which the air flows back into the inside 46 of hub 18. This air flow system is useful for cooling the air within hub 18 in that the air when flowing through rotor blade 20 is cooled at the inner surface of rotor blade 20 so as to re-enter hub 18 as cooled air. However, this system can also be used to heat the air inside the hub, such as during winter time or cold weather conditions. By means of sensors (not shown) the temperature difference between hub and blade inner air temperatures can be determined while a controller (not shown) controls the heat transfer by activating or deactivating fan 30 so that cooling is provided if the temperature difference between blade and hub inner air temperatures would allow cooling or heating effect as desired.

    Fig. 3 shows a passive air flow means 47 not falling within the scope of the claims. As far as the elements shown in Fig. 3 are identical in their construction or function to the elements shown in Fig. 2, the same reference numerals are used in Fig. 3.



    [0013] Passive air flow means 47 according to Fig. 3 includes at least one opening 48 at tip 22 of at least one of rotor blades 20. In this means, tip 22 of rotor blade 20 includes three openings 48. Moreover, in passive air flow means 47 air can be sucked into interior 46 of hub 18 from outside of rotor blade 20, which is indicated in Fig. 3 by arrows 50. Upon rotation of the rotor provided with passive air flow means 47 according to Fig. 3, due to the Venturi effect an under-pressure or vacuum is generated in inner space 34 of rotor blade 24. This under-pressure or vacuum causes an air flow 26 directed from inner space 46 of hub 18 towards openings 48 at tip 22 of blade 20. Due to the vacuum and under-pressure within hub 18, ambient air is sucked from outside of the rotor into hub 18 for cooling purposes.

    [0014] By means of various embodiments of the present invention components located inside the hub like rotor blade actuator drives (motors), converters and batteries can be effectively cooled or kept at a more constant temperature close to their optimal design temperatures. Due to this cooling or temperature control effect, it is easily possible to design motors and converters for the pitch application because the temperature ratings do not need to be extreme. Also installation of wind turbines at higher altitudes would be more feasible. Finally, the lifetime of the batteries would increase as the operation or temperature would be held more constantly and closer to the optimal design temperature. Finally, temperature control within the hub is also useful with regard to wind energy turbine types having arranged heat generating elements within the nacelle and rather close to the rotor. On high-temperature sites or high-altitude sites also for current gear box design wind turbines, various embodiments of the present invention would be suitable in order to cool the hub located next to the gear box.

    [0015] While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the scope of the claims.
    PARTS LIST
    10 wind energy turbine
    12 tower
    14 nacelle
    16 rotor
    18 hub
    20 blade
    22 tip
    24 root
    26 air flow
    28 means
    30 fan
    32 outer shell
    34 inner space
    36 half spaces
    38 half spaces
    40 inner supporting wall
    42 inlet opening
    44 outlet opening
    46 inner space
    46 interior
    47 passive air flow means
    48 openings
    50 arrows



    Claims

    1. A rotor (16) for a wind energy turbine (10) comprising:

    a hub (18) defining an inner space (34);

    at least one rotor blade (20) defining an inner space and having a tip (22) and a root (24) attached to said hub;

    wherein the inner spaces of said hub and said at least one rotor blade are in fluid communication;

    air flow (26) means causing air to flow out of the hub into the at least one rotor blade;

    wherein said air flow (26) means comprises at least one fan (30); and

    wherein said at least one rotor blade (20) comprises an outer shell (32) and an inner supporting wall (40) extending longitudinally through said rotor blade from its root (24) towards its tip (22) so as to separate said at least one rotor blade into two half spaces (36, 38) being in fluid communication to each other at said tip of said rotor blade and to said hub at said root of said rotor blade, and wherein the air is blown by said fan (30) in the one half space of said at least one rotor blade while the blown air re-enters said hub via the other half space of said rotor blade;

    said rotor (16) further comprising sensors for determining a temperature difference between hub (18) and blade (20) inner air temperatures; and characterized in that it further

    comprises a controller configured to control heat transfer by activating or deactivating the fan (30) so as to provide a cooling or heating effect in the hub (18) in order to maintain a temperature in the hub (18) substantially constant.


     
    2. A method for controlling the temperature inside a hub (18) of the rotor (16) according to claim 1, comprising providing an air flow (26) between an inner space (46) of the hub (18) into the first portion of the at least one blade (20) and further to the second portion of the at least one blade from which the air flow re-enters into the inner space of the hub, wherein the temperature of the air is influenced by the temperature of the at least one blade through which the air flows.
     


    Ansprüche

    1. Rotor (16) für eine Windenergieturbine (10), umfassend:

    eine Nabe (18), die einen Innenraum (34) definiert;

    mindestens ein Rotorblatt (20), das einen Innenraum definiert und eine Spitze (22) und einen Fuß (24) hat, der an der Nabe befestigt ist;

    wobei die Innenräume der Nabe und des mindestens einen Rotorblatts in Fluidverbindung stehen;

    Luftstrom(26)-Mittel, das bewirkt, dass Luft aus der Nabe heraus in das mindestens eine Rotorblatt strömt;

    wobei das Luftstrom(26)-Mittel mindestens einen Lüfter (30) umfasst; und

    wobei das mindestens eine Rotorblatt (20) eine Außenhülle (32) und eine Innenstützwand (40) umfasst, die sich längs durch das Rotorblatt von seinem Fuß (24) in Richtung auf seine Spitze (22) erstreckt, um so das mindestens eine Rotorblatt in zwei halbe Räume (36, 38) zu teilen, die in Fluidverbindung miteinander an der Spitze des Rotorblatts und mit der Nabe am Fuß des Rotorblatts stehen, und wobei die Luft durch den Lüfter (30) in den einen Halbraum des mindestens einen Rotorblatts geblasen wird, während die geblasene Luft wieder in die Nabe über den anderen Halbraum des Rotorblatts eintritt;

    wobei der Rotor (16) ferner Sensoren zum Bestimmten einer Temperaturdifferenz zwischen Naben- (18) und Blatt- (20) Innenlufttemperaturen umfasst; und dadurch gekennzeichnet, dass er ferner einen Controller umfasst, der zum Steuern der Wärmeübertragung durch Aktivieren oder Deaktivieren des Lüfters (30) ausgelegt ist, um so für einen Kühl- oder Erwärmungseffekt in der Nabe (18) zu sorgen, um so eine Temperatur in der Nabe (18) im Wesentlichen konstant zu halten.


     
    2. Verfahren zum Steuern der Temperatur im Innern einer Nabe (18) des Rotors (16) nach Anspruch 1, das das Vorsehen eines Luftstroms (26) zwischen einem Innenraum (46) der Nabe (18) in den ersten Teil des mindestens einen Blatts (20) und weiter zum zweiten Teil des mindestens einen Blatts umfasst, von dem aus die Luft wieder in den Innenraum der Nabe eintritt, wobei die Temperatur der Luft durch die Temperatur des mindestens einen Blatts beeinflusst wird, durch welches die Luft strömt.
     


    Revendications

    1. Rotor (16) pour une turbine éolienne (10) comprenant :

    un moyeu (18) définissant un espace intérieur (34) ;

    au moins une pale de rotor (20) définissant un espace intérieur et ayant une extrémité (22) et une emplanture (24) attachée audit moyeu;

    dans lequel les espaces intérieurs dudit moyeu et de ladite au moins une pale de rotor sont en communication de fluide ;

    un moyen de flux d'air (26) amenant de l'air à s'écouler hors du moyeu dans l'au moins une pale de rotor ;

    dans lequel ledit moyen de flux d'air (26) comprend au moins un ventilateur (30) ; et

    dans lequel ladite au moins une pale de rotor (20) comprend une enveloppe extérieure (32) et une paroi de support intérieure (40) s'étendant de façon longitudinale à travers ladite pale de rotor à partir de son emplanture (24) vers son extrémité (22) de façon à séparer ladite au moins une pale de rotor en deux demi-espaces (36, 38) en communication de fluide l'un avec l'autre au niveau de ladite extrémité de ladite pale de rotor et avec ledit moyeu au niveau de ladite emplanture de ladite pale de rotor, et dans lequel l'air est soufflé par ledit ventilateur (30) dans le demi-espace de ladite au moins une pale de rotor tandis que l'air soufflé entre de nouveau dans ledit moyeu par l'intermédiaire de l'autre demi-espace de ladite pale de rotor ;

    ledit rotor (16) comprenant en outre des capteurs pour déterminer une différence de température entre des températures d'air intérieures de moyeu (18) et de pale (20) ; et caractérisé en ce qu'il comprend en outre une unité de commande configurée pour commander un transfert de chaleur en activant ou en désactivant le ventilateur (30) de façon à procurer un effet de refroidissement ou de chauffage dans le moyeu (18) afin de maintenir une température dans le moyeu (18) sensiblement constante.


     
    2. Procédé pour commander la température à l'intérieur d'un moyeu (18) du rotor (16) selon la revendication 1, comprenant la fourniture d'un flux d'air (26) entre un espace intérieur (46) du moyeu (18) dans la première partie de l'au moins une pale (20) et en outre à la seconde partie de l'au moins une pale à partir de laquelle le flux d'air entre de nouveau dans l'espace intérieur du moyeu, dans lequel la température de l'air est influencée par la température de l'au moins une pale à travers laquelle l'air s'écoule.
     




    Drawing









    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description