AU2013228000B2

AU2013228000B2 - Fan Blade

Info

Publication number: AU2013228000B2
Application number: AU2013228000A
Authority: AU
Inventors: Cristian Care
Original assignee: Beacon Lighting International Ltd
Current assignee: Beacon Lighting International Ltd
Priority date: 2012-09-14
Filing date: 2013-09-11
Publication date: 2017-07-13
Anticipated expiration: 2033-09-11
Also published as: AU2013228000A1

Abstract

A fan blade having a root and a tip joined by leading and trailing edges, the root being adapted to be secured to a 5 mount defining a datum plane, the mount being pivotable from a first position in which the blade is retracted into a second operating position in which the blade extends radially outwardly, the leading edge being above the trailing edge and the height of the leading and trailing 10 edges relative to the datum plane being substantially constant along the length of the blade, the leading edge of the blade having a cut out that allows the blade to retract whilst overlapping an adjacent blade without contact between the blades. 46689241 (GHMatters) P90022.AU.1 11/09/13

Description

1 2013228000 11 Sep 2013

FAN BLADE

This invention relates to a fan blade for a ceiling fan and in particular relates to a fan blade for use in a 5 ceiling fan that has retractable blades.

Ceiling mounted fans with retractable blades are well known. Often fans of this kind incorporate a light and the blades when retracted are arranged to nest above the 10 light when the fan is not in operation. When the fan is turned on the blades pivot radially outwardly to an in use configuration to be rotated by an electric motor to cause the required airflow. Since the main purpose of a ceiling fan is to cause airflow it is important that the blades 15 are designed to provide this effect. A problem with retractable blades is that if the blade is to be retracted to be concealed behind a light there is a limitation to the length and width of the blade, which means that fans with retractable blades are often criticized for having 20 ineffective airflow.

The inclination of the blade and the position of the tip of the blade relative to the root of the blade together with the potential of placing a cambered surface 25 on the blade are all features that have been proposed in the past as a means of improving airflow.

Fans with the retractable blades are usually designed so that the blades are obscured by the light when 30 retracted with the blades overlapping one another when retracted without causing an unsightly stack of retracted blades. All of these issues tend to detrimentally affect the airflow characteristics of the blades, and it is these issues that have brought about the present invention. 35

In one aspect of the present invention there is provided a fan blade for use in a ceiling fan having 4668924,1 (GHMatters) P90022.AU.1 11/09/13 I3:\dcr\liUlirwoven\NRPc)i-tbt\DC:C\DER\14748404_l.doc-K-S/06/20l7 2013228000 08 Jun2017 - 2 - retractable blades the fan blade having a root and a tip joined by leading and trailing edges, the root being adapted to be secured to a mount defining a datum plane, the mount being pivotable from a first position in which the blade is retracted 5 into a second operating position in which the blade extends radially outwardly, the leading edge being above the trailing edge and the height of the leading and trailing edges relative to the datum plane being substantially constant along the length of the blade, the leading edge of the blade having a cut 10 out that allows the blade to retract whilst overlapping an adjacent blade without contact between the blades.

In accordance with a further aspect of the present invention there is provided a ceiling fan comprising an 15 electric motor driving a plate to rotate about a rotation axis, the plate pivotally supporting four equally spaced mounts, each mount supporting a fan blade according to any one of the preceding claims, whereby when the blades are in the retracted position, the tip of each blade subtends at angle of between 20 130° and 150° to the rotation axis of the fan.

According to a still further aspect of the invention there is provided a ceiling fan comprising an electric motor arranged to drive a plate to rotate about a rotational axis, the plate 25 supporting a plurality of equally spaced mounts, each mount supporting a fan blade as defined above and a sprocket that engages an endless chain whereby the sprocket and chain arrangement ensures synchronisation of the pivotal movement of the fan blades . 30

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which: 35 Figure 1 is a plan view of a fan blade that forms part of 2013228000 11 Sep 2013 3 a ceiling fan,

Figure 2 is a side elevational view of the blade, 5 Figure 3 is an underside view of the blade,

Figure 4 is another side elevational view of the blade,

Figure 5 is yet another side elevational view of the 10 blade,

Figure 6 is a cross sectional view taken along the lines A-A of Figure 1, 15 Figure 7 is a cross sectional view of the blade taken along the blades B-B of Figure 1,

Figure 8 is a cross sectional view of the blade taken along the lines C-C of Figure 1, 20

Figure 9 is a plan view of a blade secured to a mounting fulcrum,

Figure 10a is a cross sectional view taken along the lines 25 A-A of Figure 9,

Figure 10b is a similar sectional view showing a variation of the mount; 30 Figure 11 is a plan view of the rotor with the four blades mounted thereon in a retracted configuration;

Figure 12 is a plan view of a single fan blade secured to a plate via a fulcrum in accordance with another 35 embodiment of the invention; and

Figure 13 is a side elevational view of the assembly of 4668924_1 (GHMatters) P90022.AU.1 11/09/13 2013228000 11 Sep 2013 4

Figure 12.

In Australian patent 2010100672 ('672) there is disclosure of a ceiling fan with retractable blades. The 5 disclosure of this patent is incorporated herein by reference. Figures 10 and 11 of '672 illustrate a rotatable plate 60 that is driven by an electric motor (not shown) to rotate the blades about an axis through the centre of the plate. Each blade 10 is mounted on the 10 plate via a fulcrum 50.

The plate 60 and fulcrum 50 and rotational movement of the blades from the operative to the inoperative position is shown in '672 and are not described herein in 15 detail.

Figures 1 to 8 of this specification illustrate a modified fan blade 10. 20 Each blade 10 is injection moulded in translucent plastics. The blade 10 is scimitar shaped so that in plan, the blade is arcuate having an inner root 11 and an outer tip 12 joined by a leading edge 15 and a trailing edge 16. The surface 20 of the blade is cambered and in 25 its normal operating configuration is concave downwardly. The root 11 of the blade 10 defines a mount that allows the blade to be secured to the fulcrum 50 which is in turn secured to the rotatable plate 60, see Figure 11. 30 The blade 10 is mounted so that the trailing edge 16 is parallel to the horizontal when the fan is suspended from a ceiling (Figure 2). The surface 20 of the blade 10 curves upwardly from the trailing edge 16 to join the leading edge 15 which, as shown in plan, has a first 35 arcuate portion 21 and a cut-out 22 which joins the tip 12. The cut-out which is a straight line cut back towards the trailing edge. The cut back 23 then joins another 4668924_1 (GHMatters) P90022.AU.1 11/09/13 2013228000 11 Sep 2013 5 straight edge 24 that merges with the tip 12. An arcuately curved edge 25 joins the leading edge 15 to the trailing edge 16 at the top 12. As shown in Figure 7, the leading edge 15 of the blade is considerably higher than 5 the trailing edge 16 but the height of both edges 15, 16 is substantially constant along the length of the blade 10, except for the arcuate tip 12 which, as mentioned above, joins the leading edge 15 to the trailing edge 16. The cut out 22 is provided in the blade 10 to facilitate 10 stacking of the blades 10 where the tip 12 of one blade sits over the root 11 of the adjacent blade. The cut out 22 prevents one blade contacting the adjacent blade by accommodating the highest region of the rear half of the adjacent blade namely the region adjacent the leading edge 15 15.

As shown in Figure 6, 7, 10a and 10b, the root 11 of the blade 10 has three extending cylindrical pillars 31, 32, 33 that are adapted to be secured to the fulcrum 50 by 20 the fasteners (not shown) mounted with their accessible through appropriately positioned apertures 34, 35, 36 in the upper surface 20 of the blade 10. The base of the pillars 31-33 define a wall 37 enabling fasteners to be inserted through the spigots 31-33 from the top of the 25 blade 10 to enable the blade 10 to be screwed to the fulcrum 50 that includes appropriately positioned threaded female mounts 51-53 which accommodate the fasteners. The vertically extending pillars 31-33 ensure that the underside of the root 11 of the blade 10 where it joins 30 the fulcrum 50 is lower than the tip 12 of the blade 10.

In Figure 10b a variation is illustrated in which the pillars 31, 32 on the blade are shortened and the threaded mounts 51, 52 on the fulcrum 50 extended in length. 35

The tip 12 of the blade 10 needs to be higher than the underside of the root 11 of the blade 10 to ensure 4668924_1 (GHMatters) P90022.AU.1 11/09/13 2013228000 11 Sep 2013 6 that the blade 10 can overlap without contacting the adjacent blade in the retracted configuration.

As shown in Figure 11 the plate 60 supports four 5 equally spaced blades 10 via fulcrums 50 that rotate on the plate 60 from an operative position (not shown) to a retracted overlapping position within the confines of the plate 60. The tip of each blade subtends at an angle of between 130° to 150° to a line drawn radially from the 10 central axis of the fan through the pivot axis of the blade. In one embodiment this angle is 132°.

The fan blade 10 described above has been specifically designed to provide efficient retractability 15 whilst serving an adequate role as a fan. The downward trailing edge of the blade and the cambered cross section as the trailing edge joins the leading edge, provides the necessary cross section to cause the required airflow as the fan spins in the operative position. The scimitar 20 shape of the blade coupled with the stepped mount ensures that the tip of the blade is higher than the base of the mount, which means that when the blade is retracted the tip of the blade sits over but close to the root of the adjacent blade. This allows the blades when retracted to 25 sit in a compact stack without the unsightly bulk that is often present in other fans of this kind. The cut out 22 in the leading edge of the blade ensures that adjacent blades can pivot from the operative to the inoperative positions without contact. The land that is formed by the 30 hump between the arcuate portions of the trailing edge increases the cross section of the blade to further increase airflow. The curved surface of the blade to the trailing edge also improves the overall rigidity of the blade and reduces the likelihood of the blade flexing in 35 use.

In this way, the blade is retractable without 4668924_1 (GHMatters) P90022.AU.1 11/09/13 2013228000 11 Sep 2013 7 abutting contact, sits in a compact stacked configuration when retracted within the periphery of a light, and when in the operative position, has an air moving cross-section to provide the volume and spread of air movement to 5 operate efficiently as a fan.

By mounting the blades of the fan on a rotor via fulcrums of the kind described above and using the tie bars and an arcuate slot that controls movement of the 10 fulcrum provides a fan with the advantages disclosed in Australian patent 2010100672 with improved aerodynamic qualities .

In another embodiment shown in Figures 12 and 13 the 15 fulcrum 50 on which each blade 10 is mounted supports a sprocket 100. Each fulcrum 50 is confined to a small degree of rotational movement by an accurate slot 127 in the mounting plate 60. The slot 127 defines the degree of movement between the retracted and operational positions 20 of the fan blade. Each sprocket 100 has an external periphery with teeth 101 that are arranged to mesh with a continuous chain 110 that extends between the four sprockets 100. The relationship between the sprockets 100 and the chain 110 provides synchronisation of the blades 25 10 and ensures that the movement of each fulcrum 50 causes an identical movement of the other fulcrums 50 to maintain the synchronisation.

As in the earlier embodiment the blades fly open to the 30 operational position due to the centrifugal forces of the fan as it spins. A series of springs (not shown) cause the blades to return to the retracted position as the speed of the fan slows down and the centrifugal force becomes less than the spring force. The use of sprockets 35 and a single chain does away with the tie-bars shown in Figure 11 and provides a simpler and less obstructive mechanism to control the movement of the blades from the 4668924_1 (GHMatters) P90022 AU 1 11/09/13 2013228000 11 Sep 2013 - 8 - operative to the retracted positions.

Although the chain is shown as a series of interlinked spaces that fit within recesses in the 5 periphery of the socket it is understood that the chain could comprise interconnected links that ride on and engage projecting teeth of the sprocket. 4668924J (GHMatters) P90022.AU.1 11/09/13

Claims

CLAIMS :

1. A fan blade having a root and a tip joined by leading and trailing edges, the root being adapted to be secured to a mount defining a datum plane, the mount being pivotable from a first position in which the blade is retracted into a second operating position in which the blade extends radially outwardly, the leading edge being above the trailing edge and the height of the leading and trailing edges relative to the datum plane being substantially constant along the length of the blade, the leading edge of the blade having a cut out that allows the blade to retract whilst overlapping an adjacent blade without contact between the blades.
2 . The blade according to claim 1 wherein the cut out is positioned between the middle of the blade and the tip .
3. The blade according to either claim 1 or claim 2 wherein in plan the blade is scimitar shaped defining an upper curved surface joining the leading edge to the trailing edge, the upper surface being downwardly concave.
4 . The blade according to any one of the proceeding claims wherein the underside of the blade, at the root, has a plurality of downwardly extending pillars that are adapted to be secured to the mount.
5. The blade according to claim 4 wherein countersunk fasteners extend through the pillars from the upper surface.
6. The blade according to any one of the proceeding claims wherein the cut out is defined by an angle cut towards the trailing edge merging into a straight edge tapering towards the tip.
7. The blade according to claim 6 wherein the cut out accommodates the highest region, that is the region adjacent the leading edge of the rear half of the adjacent blade.
8. A ceiling fan comprising an electric motor arranged to drive a plate to rotate about a rotation axis, the plate pivotally supporting four equally spaced mounts, each mount supporting a fan blade according to any one of the preceding claims that can pivot from a retracted position to an operative position, whereby when the blades are in the retracted position, the tip of each blade subtends at angle of between 130° and 150° to the rotation axis of the fan.
9. The ceiling fan according to claim 8 wherein each mount is constrained to pivot about a slot in the plate from the retracted position to the operative position.
10. The ceiling fan according to claim 9 wherein each mount supports a sprocket and the sprockets are interconnected by a chain whereby pivotal movement of the mounts is synchronised.
11. A ceiling fan comprising an electric motor arranged to drive a plate to rotate about a rotational axis, the plate supporting a plurality of equally spaced mounts, each mount supporting a fan blade as defined in any one of claims 1 to 7 and a sprocket that engages an endless chain whereby the sprocket and chain arrangement ensures synchronisation of the pivotal movement of the fan blades.