Fluid reaction surfaces (i.e. – impellers) – Specific blade structure – Formed with main spar
Reexamination Certificate
1999-06-07
2001-01-23
Verdier, Christopher (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Specific blade structure
Formed with main spar
C416S230000, C416S239000, C416S248000
Reexamination Certificate
active
06176681
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a rotor blade to be attached on a hub of a fan or the like, comprising a blade-part, produced essentially of a composite material of fibre reinforced plastic, and an integrated foot, having at least one body for attachment of the rotor blade on the hub of the fan, and at least one reinforcement means which is essentially rigid in its longitudinal direction the reinforcement means, being fastened to the body and extending at least along one of the sides of the blade-part.
BACKGROUND OF THE INVENTION
There is today a need of producing rotor blades of a material, which may resist an aggressive environment, for instance, in the chemical process industry, and which are relatively light, resulting in that the fan, on which the rotor blades are mounted, may be operated at higher speed and that in certain cases, the rotor blades may also be made smaller and thus less expensive. Attempts have therefore been made to produce rotor blades of composite material, such as fibre reinforced plastic.
Through U.S. Pat. No. 4,877,376 a rotor blade of fibre reinforced plastic is previously known, which has relatively low weight and may accordingly be operated at high speed. However, the fastening of the rotor blade is complicated, partly due to a bolt joint having bolts extending through a pressure flange, abutting against the plastic material, to a hub or an attachment device, and partly due to a shank, which extends into the attachment device and co-operates with means to provide a pre-stress of the rotor blade. In an aggressive environment such fastening is unsatisfactory, even if the material in the rotor blade is chemically resistant, the area around the pressure flange will be both chemically and mechanically affected. Thus, it has been shown that rotor blades, having fastening means of this kind, are subjected to great stress, during high speed, and thus tend to be destroyed by propagating cracks, arising in the area of the bolt joint.
Through U.S. Pat. No. 4,966,527 a rotor blade of fibre reinforced plastic is also previously known, which has relatively low weight and may accordingly be operated at high speed. However, the fastening of the rotor blade is complicated, with fibres forming loops around several mounting elements near the blade root, which elements extend substantially parallel to the sides of the blade.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a simple and durable fastening of a rotor blade made of composite material, which also resists an aggressive environment. An additional object is to improve the operation conditions of the rotor blade.
These objects are achieved according to the invention with a rotor blade, which is characterised in that said body is arranged to withstand a state of strain, acting in several axially different directions, and that said body extends, mainly perpendicular to the sides of the blade, through the foot to both sides of the blade-part, and comprising fastening means located on each side of the blade-part.
In a preferred embodiment, the foot of the rotor blade comprises at least two bodies, preferably made of metal, such as steel or similar, which effectively may withstand a state of strain, acting in several axially different directions. The two bodies extend perpendicular through the foot to both sides of the blade and suitably each body consists of a beam, having a rounded lower edge. The two bodies may also be integrated with each other so as to from an H-shaped girder construction. Naturally, it is possible to use a body shaped like a plate, provided with recesses for the reinforcement means, or use only one beam, which by way of example is arranged obliquely in relation to the blade.
The reinforcement means suitably comprise an amount of orientated fibres and includes in a preferred embodiment, at least a bundle carbon fibre, which during manufacturing of each rotor blade in a mould, is placed around the body and lead out over the sides of the blade. Naturally, the reinforcement means may also be fastened to the body, for instance, by leading a bundle carbon fibre through a hole in the body, whereas it is fastened with a knot or similar, fastening having a larger diameter than the hole.
The composition of fibres and plastic in the composite material of the foot of the rotor blade is preferably selected such that the composite material has an elongation by temperature adapted to the body. The composite material is suitable made of glass-fibre reinforced epoxy resin.
REFERENCES:
patent: 3554664 (1971-01-01), Cheeseman et al.
patent: 3734642 (1973-05-01), Dixon
patent: 4877376 (1989-10-01), Sikorski et al.
patent: 4884948 (1989-12-01), Sikorski
patent: 4966527 (1990-10-01), Merz
Gr{umlaut over (a)}nfors Sören
Johansson Ingemar
Stromberg Karl-Otto
ABB Fl{umlaut over (a)}kt AB
Burns Doane Swecker & Mathis L.L.P.
Verdier Christopher
LandOfFree
Rotor blade with improved attachment on a hub of a fan does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rotor blade with improved attachment on a hub of a fan, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rotor blade with improved attachment on a hub of a fan will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2492374