Generator for a windmill, stator module for use in such a generator and use of such a generator

{
  "publication_number": "US6781276B1",
  "country": "US",
  "kind": "B1",
  "title": "Generator for a windmill, stator module for use in such a generator and use of such a generator",
  "abstract": "The invention concerns a generator for a windmill. The generator is of the kind being directly coupled to the main shaft of the wind rotor of the windmill. The generator is a stator consisting of a number of stator modules that are individual and which may be installed, repaired and dismantled individually and independently of each other. This implies that it is very easy and thereby cheaper to mount the mill, especially at sea, as the stator for the generator can be transported in smaller units, which also makes it easier to assemble the stator in the tower top section. By sequent repairs and other maintenance of the generator it is not necessary either to use large cranes, but it is sufficient to use smaller hoisting devices that may be handled by one or two persons.",
  "claims": [
    "1. Generator, preferably for a windmill and especially of the kind driven directly by the rotor of the windmill without any gearbox (5) installed between the rotor and the generator, wherein at least the stator of the generator (12) is made with at least two modules (20) which are fully enclosed and sealed, and that these at least two modules (20) may be mounted and dismantled independently of each other one or more at a time without dismantling the entire winding (25), characterised in that each single stator module (20) is individually contained in an enclosure (23) with a degree of sealing substantially corresponding to the degree of sealing which is desired in the finished generator (12), and that a given number of juxtaposed enclosures (23) abutting on each other form a closed ring of stator modules (20), and wherein the width of the air gap (A) between the rotor and the stator may be adjusted individually for each stator module (20) and independently of each other by suitable adjusting shims (26), by adjusting a distance between an outer periphery (d) of the stator structure and an inner periphery (D) of a given stator module (20).",
    "2. Generator according to claim 1, characterised in that each single stator module (20), when they are installed in a stator, together form a closed ring of stator modules having a diameter which does not substantially exceed the diameter of the air gap of the generator.",
    "3. Generator according to claim 1, characterised in that each single stator module (20) may be displaced radially on the stator structure with the purpose of adjusting the air gap (A).",
    "4. Generator according to claim 1, characterised in that the magnetic circuit in each single stator module is completely or substantially provided by iron having directional magnetic properties.",
    "5. Generator according to claim 1, characterised in that the generator (12) is mounted on a shaft (14), and the stator during mounting and repair work may be turned in relation to the main shaft (8) of the windmill without this requiring substantial dismantling besides the moment support of the generator.",
    "6. Generator according to claim 1, characterised in that the generator (12) during mounting and repair works may be turned in relation to a main shaft (8) of a windmill, in such a way that each single stator module (20) essentially may be lowered vertically to the ground or sea surface.",
    "7. Generator according to claim 1, characterised in that the stator comprises between 2 and 48 modules (20), preferably 24 modules.",
    "8. Generator according to claim 1, characterised in that the juxtaposed enclosures (23) have an inner surface facing inward toward the rotor (15) and forming the inner periphery (D) for the stator, that the inner periphery (D) of the stator is circular, that the rotor has an outer periphery (d) which is also circular, and that the air gap (A) between the outer periphery (D) of the rotor and the inner periphery (d) of the stator substantially have a constant width between 2 mm and 10 mm, preferably 5 mm.",
    "9. Stator module for use in a generator according to claim 1, which stator module comprises at least two poles and a number of windings around the poles, characterised in that the stator module is intended for constituting a part of a complete stator, and that the stator module is contained in an enclosure with a degree of sealing corresponding to a given desired degree of enclosure.",
    "10. Use of a generator according to claim 1 in a windmill."
  ],
  "description_excerpt": "The present invention relates to a generator for a windmill of the kind driven directly by the rotor of the windmill without any gearbox installed between the rotor and the generator wherein at least the stator of the generator is made of modules of which one or more stator modules can be dismantled independently without having to dismantle the entire winding. It is known that it is necessary to insert a speed increasing gearbox between the rotor and the generator of a windmill The rotational speed is of the magnitude 20 rpm for large windmills while a normal 4-pole generator has a synchronous speed of rotation of 1500 rpm. A suitable speed increasing gearbox will thus have a gear ratio of 1:75.\n\nIt is known that the speed increasing main gearbox of a windmill constitutes a substantial part of the cost price, and besides that it is a relatively vulnerable main component. In many cases, by possible damages, it will be necessary to dismantle the gearbox for repair. In consideration of the gearbox for a windmill in the 2 MW class having a weight of up to 15 tons and being mounted in a machine disposed on a tower with a height of 60-100m it is obvious that such a replacement may be very costly. The risk of incurring considerable expenses by a possible replacement is multiplied if large windmills are erected at sea Handling of weights of 15 tons or more in 60-100 m height may only be performed with very large float cranes or very large mobile cranes placed on large barges. Working with this kind of equipment at the open sea can only be done under good weather conditions.",
  "cpc": [
    "H02K 7/1838",
    "C07B 2200/11",
    "C07H 21/00",
    "C40B 40/12",
    "F03D 13/10",
    "F03D 15/20",
    "F03D 80/50",
    "F03D 9/25",
    "F05B 2220/7066",
    "F05B 2230/60",
    "F05B 2280/101",
    "F05B 2280/5008",
    "G01N 2333/255",
    "G01N 2400/50",
    "G01N 33/54353",
    "G01N 33/56916",
    "H02K 1/148",
    "H02K 15/02",
    "H02K 15/50",
    "H02K 2201/03",
    "H02K 2213/12",
    "H02K 5/10",
    "Y02E 10/72",
    "Y02P 70/50"
  ],
  "ipc": [
    "C07B 61/00",
    "C07H 21/00",
    "C07H 7/02",
    "C08B 37/00",
    "C12P 19/04",
    "C12Q 1/02",
    "F03D 9/00",
    "G01N 33/53",
    "G01N 33/543",
    "G01N 33/569",
    "H02K 1/18"
  ],
  "assignees": [
    "Bonus Energy AS"
  ],
  "inventors": [
    "Henrik Stiesdal",
    "Peter Rasmussen"
  ],
  "filing_date": "2000-03-31",
  "publication_date": "2004-08-24",
  "grant_date": "2004-08-24",
  "priority_date": "1998-12-15",
  "application_number": "US-93771101-A",
  "family_id": "43607756",
  "cited_by_count": 141,
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}