FIELD OF INVENTION
This invention relates to an axial flow fibber reinforced plastic fan. In particular this invention relates to a fan having an improved aerodynamic shape of blades and hub construction.
PRIOR ART
Axial flow FRP fans, presently in use in most of industries, are of old design. These are made of metal and formed by step of casting. These have low efficiency and consume more power. These fans are made of aluminium or of low carbon steel and are substantially heavier in weight. These require frequent maintenance of mechanical drive system. The systems being bulky, generate high noise and vibrations. Further, as the system has to handle humid air, they are vulnerable to corrosion.
The operating mechanical efficiency of any axial flow fan depends on blade profile, tip clearance, inlet and outlet cone shapes, number of blades, hub diameter, fan ring ovality, shape of nose spinners, support mountings, etc. The efficiency of the system can be improved through improved design of these components. Considering the large power consumed by fans, which is of the order of about 8-10% of the total power consumed in spinning mill and of the order of 15-20% of the total power consumed in composite mills. Any improvement in efficiency and resultant energy savings would be beneficial. It is estimated that by an appropriate fan system, 25% of energy can be saved.
OBJECTS OF THE PRESENT INVENTION
An object of this invention is to propose an improved axial flow fan which can be adopted for use in textile industries for humidification and air conditioning plants.
Another object of this invention is to propose an improved axial flow fan having a higher efficiency.
Still another object of this invention is to propose an improved axial flow fan which is energy efficient with lesser power consumption by around 25%.
Further object of the present invention is propose axial flow fan of Fibre reinforced Plastic (FRP) material to reduce weight of the system and to improve life of mechanical drive system.
Still further object of the present invention is to propose use of FRP material for different components of axial flow fan to make them corrosion resistant thereby enhancing their life.
Further objects and advantages of this invention will be more apparent from the ensuing description.
STATEMENT OF INVENTION
According to this invention there is provided an axial flow fibre reinforced plastic fan comprising a fan casing, aerodynamic fan blades held to hub, a clearance being provided between the tip of said fan blades and the said casing, a prerotator provided at the leading end and a straightener provided at the trailing end of said casing, an inlet cone with a nose fairing disposed therein, an outlet cone with a tail fairing disposed therein, characterized in that the said hub comprising of support plates with blade holding blocks at the periphery comprising two members and spaced from each other, a central bush being disposed between said holding blocks and the blades being held by a fastening means having a tapered shank with head.
DESCRIPTION OF FIGURES
Fig. 1: shows the construction of the axial flow fibre reinforced plastic fan
of the present invention.
Fig.2: shows the construction of hub of the axial flow fan.
DESCRIPTION OF INVENTION
Reference is made to Fig. 1 of the accompanying drawings which illustrates the axial flow fan to comprise a fan casing or ring (5). Aerodynamic fan blades (1) are held to a hub (2), a clearance (10) being
provided between the tip of the blades and casing (5). A prerotator (3) is provided at the leading end and a strightener (4) at the trailing end of casing (5). The axial fan further comprises an inlet cone (8) with a nose fairing (6) disposed therein, and an outlet cone (9) with a tail fairing (7) disposed therein.
Reference is now made to Fig.2 of the accompanying drawings which illustrates the hub (2) to consist of support plates (11) with blade holding blocks (12) at the periphery with a central bush (13) disposed there between. Blade holding blocks (12) consist of two members (12a) and (12b) spaced from each other. The blade is held by a fastening means having a tapered shank with head.
The fan of the present invention comprises a variable pitch fan, and thus by rotating the fan blade the angle can be changed by the holding blocks.
In accordance with this invention, the shank is disposed off center with respect to the horizontal axis. Further casing (5) is cylindrical.
It is to be noted that present invention is susceptible to modifications changes and adaptations by those skilled in the art. Such, variant embodiments incorporating the concepts and features of the present invention, are intended to be within the scope of the present invention, which is further set forth under the following claims:

WE CLAIM;
1. An axial flow fibre reinforced plastic fan comprising a fan casing (5),
aerodynamic fan blades (1) held to hub (2), a clearance (10) being
provided between the tip of said fan blades (1) and the said casing (5),
a prerotator (3) provided at the leading end and a straightener (4)
provided at the trailing end of said casing (5), an inlet cone (8) with a
nose fairing (6) disposed therein, an outlet cone (9) with a tail fairing
(7) disposed therein, characterized in that the said hub (2) comprising
of support plates (11) with blade holding blocks (12) at the periphery
comprising two members (12a) and (12b) spaced from each other, a
central bush (13) being disposed between said holding blocks and the
blades being held by a fastening means having a tapered shank with
head.
2. An axial flow fibre reinforced plastic fan as claimed in claim 1 wherein
said shank is disposed off centre with respect to the horizontal axis.
3. An axial flow fibre reinforced plastic fan as claimed in claim 1 wherein
said casing (5) is cylindrical.
4. An axial flow fibre reinforced plastic fan as substantially described and
illustrated herein.