BASE-FRAME FOR A WINDMILL HOUSING AND A WINDMILL COMPRISING SAME

Abstract: The invention concerns a base-frame for a windmill which is executed in one piece of steel plate. The plate piece is machined with the assembly points necessary for the frame. The base-frame according to the invention can maintain the same strength characteristics as a welded frame while using fewer and less pre-processed materials. The invention also relates to a windmill with a self-supporting machine shield in which the windmill's generator is housed. Moreover, the invention provides the possibility of achieving an increased damping of the structural noise, in that the scale between the windmill's larger vibrating elements, by the reduction of the base-frame's weight, can be made of the same magnitude, partly by suspending the windmill's generator in the machine shield, and partly by configuring the machine shield with vibration-damping or mass-increasing materials.

Description: BASE-FRAME FOR A WINDMILL HOUSING AND A WINDMILL COMPRISING SAME Background of the invention The invention concerns a base-frame for a windmill as disclosed in the preamble to claim 1, and a windmill as disclosed in the preamble to claim 3. Known windmills are normally executed with a welded or moulded machine frame on which the windmill's transmission and yaw systems are mounted. However, machine frames of the first type have the disad- vantage that the welds themselves have a very low fatigue strength. One of the results of this is that very high de¬ mands must necessarily be placed on the welds, the reason being that these are exposed to greatly varying loads during operation. A natural consequence of these circum- stances is that the machine frame must be executed in a re¬ latively strong material. This increases costs and, more¬ over, places great demands on the overall construction. Furthermore, the large machine frame gives rise to dis- proportionally greater noise from the machine shield associated herewith. The moulded machine frames are expensive to produce, which applies especially to larger windmills since the costs of the moulds for these frames are considerable. Moreover, the moulding of machine frames is an inflexible solution, the reason being that even small changes in the construction result in a considerable increase in costs and involve time-consuming operations. The object of the invention By making the windmill's base-frame of a solid, plane steel plate which has been machined for the purpose, there is achieved a simple construction which has surprisingly good support characteristics compared with the known con¬ structions. It is thus possible to achieve a particularly great reduction in the consumption of material, and here¬ with in the weight of the base-frame while maintaining the necessary support characteristics. Moreover, the statistical load on the windmill is reduced as a con¬ sequence of the said reduction of the base-frame's suspended mass. A further advantage is achieved in that there is a greater freedom with regard to the positioning of components on the base-frame. As disclosed in claim 2, by providing mounting points for slide-shoes and grip-hooks in the bottom of the base-frame, and mounting points for one or more yawing gears, it is achieved that the yaw system can be integrated in the base- frame in a particularly simple and space-saving manner. This further results in a reduction of the necessary ver- tical distance between the main bearing and the bedding for the windmill tower, whereby there arises a reduced moment between bedding and main bearing, which is made possible by the physically smaller extent of the base-frame in which the main bearing is housed. There is thus achieved both a more simple and more solid execution when considered as a whole. As disclosed in claim 3, by letting the mill comprise a machine shield with self-supporting construction in which the generator is suspended, the possibility is provided of a further utilization of the reduction achieved in the weight of the base-frame, in that the generator's swinging mass is also transferred to the machine shield. This makes it possible for the generator and the shield together to be damped with regard to the undesired vibrations arising in the structure by suspending the machine shield in flexible or vibration-damping mountings. The resulting possible damping of vibrations is not, however, limited to having advantages only with regard to the spreading of the structural sound and the herewith subsequent radiation of noise, but also involves great advantages with regard to the solidity of the structures, since the dynamic loads can be considerably reduced. As disclosed in claim 4, by dimensioning the windmill's arrangements so that the machine shield and the generator housed therein has a mass which is of the same magnitude as the gear and main bearing and base-frame, a strong damping is achieved especially of pure tones excited by the wind¬ mill's gear. As disclosed in claim 5, by arranging the machine shield with vibration-damping or mass-increasing materials, a further damping of the noise radiated by the machine shield is achieved, either by a direct damping of the vibrations in the structure or by increasing the structure's overall resonance frequency especially in relation to the un¬ desired pure tones. As disclosed in claim 6, by letting the vibration-damping material comprise a jacket of sand and/or a sand-filled cavity built into the housing, a simple embodiment is achieved which is inexpensive and stable in operation and has all of the hitherto-mentioned advantages. The drawing In the following, the invention will be described in more detail with reference to the drawing, where fig. 1 shows an example of a known machine construction for a windmill, fig. 2 shows a known, welded machine frame, fig. 3 shows a known yaw system, fig. 4 shows an example of a machine construction according to the invention, fig. 5a-c shows an example of a base-frame according to the invention, fig. 6 shows an example of a yaw system according to the invention, fig. 7 shows an example of a vibration-damping suspension of a machine shield according to the invention, and where fig. 8 shows an example of the noise-damping of a machine shield according to the invention. Description of the example embodiment In fig. 1 is seen an example of a known machine con¬ struction. A welded base-frame 1 foremost supports a main bearing 2 connected to a mill hub 9 and rearmost a gear 3 which is suspended in two vibration dampers 4, of which only the one is seen in the drawing. A generator 5 connected to the gear 3 is mounted on the base-frame 1. The base-frame 1 is pivotably mounted on a tower (not shown) by means of a yaw system. In fig. 2 is seen a cross-section of a known, welded machine frame 1 consisting of a base-plate 16 which is con- nected via a number of cross-plates 17 to the top plate 18. Foremost and rearmost there are reinforcements 19 on which there are mounting points for the main bearing housing and gear fittings. In fig. 3 is seen an example of a known yaw system. A slew ring 21 is disposed between a top flange 22 mounted on the tower and a transition piece 23 for a machine frame 1. Two yaw gears 24 are each provided with a yaw drive 25 which is in engagement with internal teeth 26 on the slew ring 21. Two drum-brake shoes 27 with glued-on brake linings are disposed in a brake drum 28 which is inserted between the slew ring 21 and the tower's top flange 22. A brake-shoe support 29 transfers the effect from the brake shoes 27 to a yaw gear plate 30 which is inserted between the slew ring 21 and the transition piece 23. A hydraulic cylinder (not shown) activates the brake when the mill is not yawing, and a system of springs and rods (not shown) draws the brake shoes 27 free when the mill yaws. In fig. 4 is seen an example of a machine construction according to the invention. A single base-frame 31 foremost supports a main bearing 32 and rearmost a gear 33 which is suspended in two vibration dampers 34. The base-frame 31 also comprises the one part of a yaw system 38, the other part of which is mounted on a tower. In fig. 5 is seen a more detailed example of a base-frame according to the invention. In fig. 5a, the base-frame is seen from below, in that it is executed with mounting points 44 for slide shoes which are discussed later, and mounting points 43 for yaw gears. In fig. 5b is seen a cross-section of the base-frame 31. In fig. 5c, the base-frame 31 is seen from above, in that its upper side has mounting points 41 and 42 for a main bearing housing and a gear fitting respectively. The base- frame 31 is also provided with integrated mounting points 43 for the yaw gear. The underside of the base-frame 31 is provided with a number of mounting points 43 for slide shoes for the yaw system. In fig. 6 is seen an example of a yaw system built into a base-frame 31 according to the invention. A yaw gear 51 is disposed in a recess provided in the base¬ plate 31. The yaw gear 51 has a drive 53 which is engaged in teeth 54 on a yaw ring 55. A number of slide shoes 56 are disposed on mounting points provided herefor in the base-frame 31. The slide shoes 56 are supported by a middle piece 57 for the radial fixing of the yaw ring 55. The underside of the frame 31 is further provided with yaw hooks 58 which are mounted on mounting points with slide shoes 59 arranged herefor, each of which is supported by a spring 60 and thus holds the top of the mill in place on the transition piece 61. In fig. 7 is seen an example of a suspension on a base- frame 31 according to the invention, in that a machine shield 71 is provided with ribs 72 in which there are pro¬ vided fittings 73 which support an axle for a rubber damper which is disposed in a retaining block bolted on the base- frame 31. The machine shield 71 itself is thus mounted directly on the base-frame 31 via vibration-damping arrangements. In fig. 8 is seen an example of an assembled construction according to the invention. The machine shield 71 is provided with a jacket-formed, sand-filled cavity 81, and additional sand-filled cavities 82.

Claims: P A T E N T C L A I M S 1. Base-frame for a windmill housing comprising mounting points for a windmill's main bearing and gearing, c h a r a c t e r i z e d in that the base-frame (31) con¬ sists of just a single plane piece of steel plate. 2. Base-frame according to claim 1, c h a r a c t e r ¬ i z e d in that the underside of the base-plate has in- tegrated mounting points (44) for slide shoes and grip- hooks, and mounting points for one or more yaw gears (43) . 3. Windmill with base-frame according to claims 1-2 com¬ prising a rotor which via a main bearing mounted on the base-frame is connected to a gear which is further con¬ nected to a generator, said base-frame being provided with a machine shield and mounted on a tower, c h a r a c t ¬ e r i z e d in that the machine shield ( 71 ) is configured as a self-supporting structure in which the windmill's generator (35) is suspended, in that the machine shield (71) is mounted on the base-frame (31) with an elastic and/or a vibration-damping suspension (73) . 4. Windmill according to claim 3, c h a r a c t e r i z e d in that the machine shield (71) and the elements suspended herein have a mass which is substantially of the same mag¬ nitude as the other of the windmill's masses which are ex¬ cited by the gear (33) . 5. Windmill according to claim 3 or 4, c h a r a c t e r ¬ i z e d in that the machine shield (71) is provided with vibration-damping or mass-increasing materials. 6. Windmill according to claim 5, c h a r a c t e r i z e d in that the vibration-damping material consists of a jacket of sand (81) and/or sand-filled cavities (82) built into the housing.

Inventors: STIESDAL HENRIK, STIESDAL, HENRIK
Applicants: BONUS ENERGY AS, STIESDAL HENRIK, BONUS ENERGY A/S, STIESDAL, HENRIK
Application year: 1996
Main classification: F03D11
IPC codes: F03D11