GB2064668A

GB2064668A - Fan Blade

Info

Publication number: GB2064668A
Application number: GB8036765A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-11-16
Filing date: 1980-11-17
Publication date: 1981-06-17

Abstract

The blade has a front wall 4 and a rear wall 6 which are bridged by a peripheral wall (30, 32) to define therebetween a space through which air flows from an air intake 16 at the leading edge to an exhaust opening 17 at the periphery of the front wall. <IMAGE>

Description

SPECIFICATION Improved Fan Blade This invention relates to a fan and, in particular, to an improved fan blade therefor.

Conventional fans produce a stream of air which is directed predominantly parallel to the axis of the fan rotor, so that out of line with the axis of the rotor the effects of the fan cannot be felt. If a wider area of ventilation is required, a larger diameter fan must be used.

One object of this invention is to enable a fan to ventilate a wider arc than would be possible with a conventional fan of the same diameter.

With this object in mind, I propose, in accordance with the present invention, a fan comprising a rotor on which is mounted a plurality of fan blades each having a front (having regard to the general direction of air flow) and a rear wall which are bridged by a peripheral wall to define therebetween a space open at the leading edge of the blade to provide an air intake through which, in use, air flows to an exhaust opening in the front wall of the blade in the region of a peripheral edge thereof. Preferably, the rear wall is joined to the front wall so as to define between the radially inner end of the space and the exhaust opening, an air step which gradually diminishes from the air intake at the leading edge of the blade to the trailing end of the exhaust opening.

Such a fan produced, in addition, to the usual stream of air generated by the front of the fan blade, a secondary stream of air flowing out from the exhaust opening which is disposed close to the periphery of the fan blade.

Further, an angled lip may be provided along the radially inner edge of the exhaust opening, to direct the flow of air from the exhaust outwardly at an angle to the axis of the rotor.

An embodiment of this invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a perspective view of a part of a fan rotor, only one fan blade being shown; Figure 2 is a side view of the fan blade and rotor shown in Figure 1; Figure 3 is a plan view of the fan rotor showing all three fan blades mounted thereon; Figures 4-6 are part cross-sectional views of the fan blade shown in Figures 1 and 2, taken along different lines angularly spaced from the leading edge of the blade, and Figure 7 is a diagram illustrating the flow of air produced by the fan rotor shown in Figures 1 to 6.

In the Figures, parts are designated consistently by the same reference numerals.

A fan rotor 2 secured to the shaft of a motor (not shown) by a screw or the like, carries a plurality of, in this case three, fan blades, preferably made of a plastics material or metal.

Each fan blade has a front wall 4 and a rear wall 6 which are bridged by a peripheral wall to enclose a space through which air flows from an air intake 1 6 at the leading edge of the blade, to an air exhaust 17, the air intake, being substantially parallel to the axis of the rotor, whereby a maximum inflow of air is obtained during rotation. In plan view (Figure 3), the rear wall 6 is curved such that the space between the blades is convergent toward the trailing edge and is joined to the front wall 4 along a curved line (showed dotted) extending from a position close to the root of the blade 8, forming an air step between the air intake 1 6 and the exhaust 17, which gradually diminishes (c.f.Figures 2, 4, 5 and 6) toward the trailing end of the exhaust 1 7 at the periphery of the blade, so that the outflow of air is distributed uniformly across the exhaust 17.

The peripheral wall bridging the front 4 and rear 6 walls of the fan blade includes a partcircular portion 32 which describes the outer circumference of the rotating fan, a transitional portion 34, and an inclined plane portion 30, the front edge of which also lies on the outer circumference of the rotating fan and constitutes the outer periphery of the exhaust 17, the exhaust opening being provided by a cut-out 18-20- 22-28 in the periphery of the front wall 4. The cut-out portion or flap is bent forward to form a lip 36 at an obtuse angle to the adjacent radially inner part of the front wall 4.

As with a conventional fan blade, the leading edge 8-10 of the front wall 4 is substantially normal to the axis of the rotor and the trailing edge 27-29 is inclined thereto, so that air is moved by the front surface of the front wall 4, and leaves the blade in a direction determined by the angle of inclination of the trailing edge.

In addition, however, air flowing through the blade from the intake 1 6 and out of the exhaust 1 7 leaves the fan blade at a larger radius and, further, is directed by the angled lip 36 outwardly from the exhaust at an angle of 60 to the axis of the rotor, so that the overall effect is a much more widely directed stream of air than can be achieved using a conventional fan.

Claims

1. A fan comprising a rotor on which is mounted a plurality of fan blades each having a front (having regard to the general direction of air flow) and a rear wall which are bridged by a peripheral wall to define therebetween a space open at the leading edge of the blade to provide an air intake through which, in use, air flows to an exhaust opening in the front wall of the blade in the region of a peripheral edge thereof.

2. A fan according to claim 1 wherein the rear wall is joined to the front wall so as to define the radially inner end of the space and the exhaust opening, an air step which gradually diminishes from the air intake at the leading edge of the blade and the trailing end of the exhaust opening.

3. A fan according to claim 1 or claim 2 and comprising an angled lip along the radially inner

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improved Fan Blade This invention relates to a fan and, in particular, to an improved fan blade therefor. Conventional fans produce a stream of air which is directed predominantly parallel to the axis of the fan rotor, so that out of line with the axis of the rotor the effects of the fan cannot be felt. If a wider area of ventilation is required, a larger diameter fan must be used. One object of this invention is to enable a fan to ventilate a wider arc than would be possible with a conventional fan of the same diameter. With this object in mind, I propose, in accordance with the present invention, a fan comprising a rotor on which is mounted a plurality of fan blades each having a front (having regard to the general direction of air flow) and a rear wall which are bridged by a peripheral wall to define therebetween a space open at the leading edge of the blade to provide an air intake through which, in use, air flows to an exhaust opening in the front wall of the blade in the region of a peripheral edge thereof. Preferably, the rear wall is joined to the front wall so as to define between the radially inner end of the space and the exhaust opening, an air step which gradually diminishes from the air intake at the leading edge of the blade to the trailing end of the exhaust opening. Such a fan produced, in addition, to the usual stream of air generated by the front of the fan blade, a secondary stream of air flowing out from the exhaust opening which is disposed close to the periphery of the fan blade. Further, an angled lip may be provided along the radially inner edge of the exhaust opening, to direct the flow of air from the exhaust outwardly at an angle to the axis of the rotor. An embodiment of this invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a perspective view of a part of a fan rotor, only one fan blade being shown; Figure 2 is a side view of the fan blade and rotor shown in Figure 1; Figure 3 is a plan view of the fan rotor showing all three fan blades mounted thereon; Figures 4-6 are part cross-sectional views of the fan blade shown in Figures 1 and 2, taken along different lines angularly spaced from the leading edge of the blade, and Figure 7 is a diagram illustrating the flow of air produced by the fan rotor shown in Figures 1 to 6. In the Figures, parts are designated consistently by the same reference numerals. A fan rotor 2 secured to the shaft of a motor (not shown) by a screw or the like, carries a plurality of, in this case three, fan blades, preferably made of a plastics material or metal. Each fan blade has a front wall 4 and a rear wall 6 which are bridged by a peripheral wall to enclose a space through which air flows from an air intake 1 6 at the leading edge of the blade, to an air exhaust 17, the air intake, being substantially parallel to the axis of the rotor, whereby a maximum inflow of air is obtained during rotation. In plan view (Figure 3), the rear wall 6 is curved such that the space between the blades is convergent toward the trailing edge and is joined to the front wall 4 along a curved line (showed dotted) extending from a position close to the root of the blade 8, forming an air step between the air intake 1 6 and the exhaust 17, which gradually diminishes (c.f.Figures 2, 4, 5 and 6) toward the trailing end of the exhaust 1 7 at the periphery of the blade, so that the outflow of air is distributed uniformly across the exhaust 17. The peripheral wall bridging the front 4 and rear 6 walls of the fan blade includes a partcircular portion 32 which describes the outer circumference of the rotating fan, a transitional portion 34, and an inclined plane portion 30, the front edge of which also lies on the outer circumference of the rotating fan and constitutes the outer periphery of the exhaust 17, the exhaust opening being provided by a cut-out 18-20- 22-28 in the periphery of the front wall 4. The cut-out portion or flap is bent forward to form a lip 36 at an obtuse angle to the adjacent radially inner part of the front wall 4. As with a conventional fan blade, the leading edge 8-10 of the front wall 4 is substantially normal to the axis of the rotor and the trailing edge 27-29 is inclined thereto, so that air is moved by the front surface of the front wall 4, and leaves the blade in a direction determined by the angle of inclination of the trailing edge. In addition, however, air flowing through the blade from the intake 1 6 and out of the exhaust 1 7 leaves the fan blade at a larger radius and, further, is directed by the angled lip 36 outwardly from the exhaust at an angle of 60 to the axis of the rotor, so that the overall effect is a much more widely directed stream of air than can be achieved using a conventional fan. Claims

3. A fan according to claim 1 or claim 2 and comprising an angled lip along the radially inner edge of the exhaust opening, for directing the flow of air from the exhaust outwardly at an angle to the axis of the rotor.

4. Afan having fan blades substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.