EP2729707B1

EP2729707B1 - An axial fan

Info

Publication number: EP2729707B1
Application number: EP11733826.9A
Authority: EP
Inventors: Claus Christensen-Dalsgaard
Original assignee: Multi-Wing International AS
Current assignee: Multi-Wing International AS
Priority date: 2011-07-05
Filing date: 2011-07-05
Publication date: 2015-11-11
Anticipated expiration: 2031-07-05
Also published as: EP2729707A1; WO2013004299A1

Description

FIELD OF THE INVENTION

The present invention relates to an axial fan comprising a hub and a plurality of blades. Moreover, the present invention relates to a blade for use in the axial fan according to the present invention. Furthermore, the present invention relates to a hub for use in the axial fan according to the present invention. Additionally, the present invention relates to a pitch defining element for use in the axial fan according to the present invention. Finally, the present invention relates to a kit comprising a hub, a plurality of blades and a plurality of pitch defining elements.

BACKGROUND OF THE INVENTION

In relation to axial fans, the pitch of the blades determine the amount of air which is caused to be moved by the axial fan, when the fan is rotated. It is known to provide axial fans with a predetermined pitch, however it is desirable to provide an axial fan which allows for the pitch to be adjusted.
Prior art document US 2009/0028709 (closest prior art) discloses an adjustable fan including a hub having a receiving surface and a fan blade having a base abutting the receiving surface of the hub. A plurality of keyways may be positioned in at least one of the receiving surface and the base. A key may extend between the base and the receiving surface and into at least one of the plurality of keyways in order to retain the fan blade in a desired orientation relative to the hub.
US 4,600,362 discloses an impeller for an axial fan, this impeller comprising a hub transversally split into two parts each defining recesses into root portions of a plurality of impeller blades inserted and locked by means of key-pieces when the two parts are joined together. Each key-piece has two spaced projections on one side for engaging two corresponding recesses diametrically located in the end surface of the root of each impeller blade close to the periphery of this end surface, and two equally spaced projections on its other side for engaging two corresponding recesses provided in the bottom surface of the recess in the hub. These pairs of projections on both sides of the key-piece which is preferably ring -shaped, are advantageously shifted from a certain angle along the circumference of the ring.
It is an object of one or more embodiments of the present invention, to provide an axial fan which allows for adjustment of the pitch.
It is an object of one or more embodiments of the present invention, to provide an axial fan in which the pitch cannot be adjusted during operation of the fan.

DESCRIPTION OF THE INVENTION

In a FIRST aspect, the present invention relates to an axial fan comprising a hub and a plurality of blades each of which extends away from the hub,
wherein each blade defines a blade air moving part which during rotation of the axial fan causes air to be moved relative to the axial fan, and a blade retaining part;
wherein the hub defines a plurality of hub retaining sockets each of which is adapted to retain a blade radially by engagement between the hub retaining socket and the respective blade retaining part;
wherein each blade retaining part on an outer surface defines a plurality of blade indentations with a first cross-sectional shape, and wherein each hub retaining socket on an inner surface defines a plurality of socket indentations with a second cross-sectional shape,
wherein provision of an pitch determining element is one blade indentation and in one socket indentation causes the blade to be retained at a predetermined pitch angle relative to the hub, and
wherein the pitch determining element is non-cylindrical.
By providing a pitch determining element which can be inserted into one socket indentation and one blade indentation, the blade may be retained relative to the hub in a predetermined position and thus achieve a predetermined pitch.
The axial fan according to the present invention may be used in connection with cooling of an engine/motor such as a combustion engine or an electrical motor. Moreover, the axial fan may be used in connection with snow blowers, hover-crafts and ventilation systems such as ventilation systems for use in the farming industry e.g. stables.
In the context of the present invention, the term "axial fan" shall be understood as, a fan which is adapted to move air in a direction parallel with the shaft to which the axial fan is rotated.
In the context of the present invention, the term 'pitch' shall be understood as the angle defined between the plane of rotation of the blade during use and the profile chord of the blade, the profile chord being defined as a line extending through the leading edge and the trailing edge of the blade, and the plane of rotation having the rotational axis of the hub as a normal.
In one embodiment, at least one of - such as all of - the hub retaining sockets defines two half parts each with a substantially semi-circular cross-section. When the two half parts are fastened to each other, the pair of substantially semi-circular cross-sections may define a circular cross-section.
In one embodiment, the hub defines a proximal hub part which defines a plurality of hub retaining sockets and a distal hub part which defines the same number of hub retaining sockets. When the proximal hub part and the distal hub part are fastened to each other, the plurality of circular cross-sections, may be defined. In these circular cross-sections, the blade retaining parts of the blades are retained in the radial, the axial and the circumferential direction.
It will be appreciated that by providing a plurality of socket indentations on the inner surface of hub retaining socket and a plurality of blade indentations in the outer surface of blade retaining part, the blade may be positioned and retained in a plurality of different positions.
The hub and the blades are designed such that the pitch of each blade may be set in connection with the attachment of the blade to the hub. The pitch of the blades may be changed by disconnecting the blades from the hub and subsequently attaching the blades to the hub - however at a new pitch angle. The blades may be disconnected from the hub by disengaging the proximal hub part and the distal hub part. Once these two parts are disengaged, the each blade may be rotated about an axis extending through and defining a normal to the axis of rotation of the hub. Once the new pitch angle has been established, the pitch defining element may be inserted into a blade indentation and a socket indentation which faces each other. Subsequently, the proximal hub part and the distal hub part are fastened to each other.
In the context of the present invention, the term 'axial fan' shall be understood as any fan which is suitable for cooling an object such as an engine, either by cooling a radiator which is used to cool a cooling medium that is circulated between the radiator and the object/engine and/or by cooling the object/engine directly.
The hub will typically be adapted to be connected to or fastened to an axle which is rotated so as to cause the fan to rotate. This axle may be an axle which forms an extension of the axle of the engine.
The hub and/or the blade may comprise a metal material or a plastic material or a fibre glass. Examples are iron, aluminium, polycarbonate, polystyrene, polytetrafluoroethylene, polyamid and polypropolene. It will be appreciated that any other metal or plastic material may be used.
The fan comprises a plurality of blades such as four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen etc. The blades will typically be equidistantly spaced apart circumferentially. The length of the blades may be in the range 200-2000 milimeters, such as 500 milimeters, such as 1000 milimeters, such as 1500 milimeters, such as 2000 milimeters.
Each blade defines a blade retaining part and a blade air moving part. The blade retaining part may define a circular cross-section into which one or more blade indentations are defined. The blade air moving part may be designed like any blade for moving air, and the technology is known from the technical field of wind turbines, axial fans, or any other field of technology when air is moved by means of blades.
The pitch determining element is non-cylindircal. In one embodiment, the pitch determining element defines a non-circular cross-section, such as a non-circular cross-section in a direction transverse to the longitudinal direction of the pitch determining element.
In one embodiment, the cross-sectional shape of the pitch determining element corresponds at least to that of the first and second cross-sectional shape, of the blade indentation and the socket indentation, respectively. In one embodiment, the cross-sectional shape of the pitch determining element is non-symmetrical. Accordingly, no line of symmetry may be defined in any direction through the pitch determining element.
In one embodiment, at least one of - such as both of - the first and the second cross-sectional shapes defines a polygonal shape such as a triangular shape, such as quadrangular shape. In one embodiment, at least one of - such as each of - the first cross-sectional shape and the second cross-sectional shape defines a semi circle.
When such first and a second cross-sectional shapes opposes each other, a cylindrical compartment is defined. This may be used to retain the blade retaining part and the hub retaining sockets relative to each other by insertion of a cylindrical element. However in some cases, the number and the positions of the blade indentations and the socket indentations may be found to be coarse, thus not enabling a desired fine adjustment of the pitch. In these cases, the inventors have found that the provision of a non-cylindrical element may allow for a finer adjustment of the pitch. Accordingly, the cross-sectional shape of the pitch determining element may correspond to that of two semi-circles which are displaces relative to each other. This displacement provides for the more fine adjustment of the pitch.
As an example, the line of symmetry of each of the two semi-circles may be displaced a predetermined distance. The line of symmetry being defined as the line which divides a semicircle area into two quarter-circle areas. It will be appreciated that the longer the predetermined distance is, the larger will the change in pitch be, relative to a situation where the pitch defining element defines a cylindrical shape.
In one embodiment, the predetermined distance is one millimetres, such as two millimetres, such as three millimetres, such as four millimetres, such as five millimetres.
In a SECOND aspect the present invention relates to a blade for an axial fan according to the first aspect of the invention.
The invention according to the second aspect may comprise any combination of features and/or elements of the invention according to the first aspect.
In a THIRD aspect the present invention relates to a hub for an axial fan according to the first aspect of the invention.
The invention according to the third aspect may comprise any combination of features and/or elements of the invention according to the first aspect.
In a FOURTH aspect the present invention relates to a pitch defining element according to the first aspect of the invention.
The invention according to the fourth aspect may comprise any combination of features and/or elements of the invention according to the first aspect.
In a FIFTH aspect the present invention relates to a kit comprising a hub and plurality of blades and a plurality of pitch defining elements according to the first aspect of the invention.
In one embodiment, one of the pitch defining elements comprises a pitch defining element with a circular cross-section. This pitch defining element may be cylindrical.
In one embodiment, the plurality of pitch determining elements comprises one non-cylindrical pitch defining element and one cylindrical pitch determining element.
The invention according to the second aspect may comprise any combination of features and/or elements of the invention according to the first aspect.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 discloses an axial fan comprising a hub and five blades,
Fig. 2 discloses an exploded view of an axial fan comprising a hub and five blades,
Figs. 3a and 3b disclose an end view of a blade with a non-circular pitch-determining element,
Figs. 4a and 4b disclose an end view of a blade with a circular pitch-defining element,
Figs. 5 discloses the first cross-sectional shape and the second cross-sectional shape of the pitch defining element,
Figs. 6-8 disclose different embodiments wherein the first cross-sectional shape and the second cross-sectional shape are displaced relative to each other,
Fig. 9 discloses a pitch defining element with a circular cross-section, and
Fig. 10 discloses a hub into which one blade is inserted.

DETAILED DESCRIPTION OF THE FIGURES

Figs. 1 and 2 discloses an axial fan 100 comprising a hub 102 and five blades 104. The hub 102 comprises a proximal hub part 106 which defines five hub retaining sockets 108 (corresponding to the number of blades 104) and a distal hub part 110 which additionally defines five retaining sockets 108. The proximal hub part 106 is adapted to be fastened to an axle for rotating the axial fan 100. This axle may be an axle of an engine (not shown). In one embodiment, the proximal hub part 106 and the distal hub part 110 are identical such that either of the two hub parts 106,110 may be fastened to the axle for rotating the axial fan 100.
As may be seen in Fig. 10, each of the blades 104 comprises a blade air moving part 112 and a blade retaining part 114. The blade air moving part 112 is adapted to move air located in the area of the axial fan 100 in a direction parallel to the axis of rotation 116 of the axial fan 100, such that air may be used to cool an engine - either directly by moving air along an outer surface of the engine and/or by moving air past or through a radiator (not shown) which is used to circulate a cooling agent inside the engine. This cooling agent may be water containing an anti-freezing agent or oil. It will be appreciated that during rotation of the axial fan 100, the axial fan 100 will also move air in a radial direction relative to the axis of rotation 116.
The blade retaining part 114 is used to retain the blade in relation to the hub 102. In order to do this, the blade retaining part 114 comprises a narrow zone 118 a wide zone 120. The two zones 118, 120 are adapted to engage corresponding zones of the hub retaining sockets 108. Due to the wide zone 120 being provided closer to the axis of rotation 116 than the narrow zone 118, the blade 104 is retained radially relative to the hub 102. In this position, the blade is free to be rotated about its radial axis 122, whereby any pitch may be achieved.
In order to fix each blade 104 in a predetermined position and with a predetermined pitch, a pitch defining element 124 is provided. As will be described in further detail below, the cross-sectional shape of the pitch defining element 124 may determine the pitch of the blade 104.
Each pitch defining element 124 is adapted to engage a blade indentation 126 provided on an outer surface 128 of the blade retaining part 114, and socket indentations 130 provided on an inner surface 132 of each hub retaining socket 108. By providing one pitch defining element 124 such that it engages one blade indentation 126 and one socket indentations 130, the blade is prevented from rotating about its radial axis 122.
In order to allow the blade to be retained at a plurality of different pitch angles, each outer surface 128 of each blade retaining part 114 defines a plurality of blade indentation 126. Similarly, each inner surface 132 of each hub retaining sockets 108 defines a plurality of socket indentations 130. It will be appreciated from Figs. 3 and 4 that the plurality of blade indentations 126 allows for different pitch angles, cf. the angles printed onto the end surface 129 each blade retaining part 114.
Figs. 3a-9 disclose different embodiments of the pitch defining element 124. In each case the pitch defining element 124 defines a first cross-sectional shape 134 and a second cross-sectional shape 136. It will readily be realised that the two shapes 134,136 form one single element. Thus Fig. 5, is only provided for illustrative purposes as the two shapes 134,136 in Fig. 5 do not form one single element. In the embodiment of Figs. 4a, 4b and 9, the cross-sectional shape of the pitch defining element 124' is circular as the pitch defining element 124 defines a cylindrical shape. Thus in Figs. 4a, 4b and 9, the first cross-sectional shape 134 and the second cross-sectional shape 136 are aligned. Contrary hereto, the first cross-sectional shape 134 and the second cross-sectional shape 136 are displaced relative to each other in Figs. 3a, 3b and 6-8. The effect is that the pitch of the blade may be adjusted even finer than if only the cylindrical pitch defining element 124 is provided. It will be appreciated that by providing such pitch defining element 124 where the first cross-sectional shape 134 and the second cross-sectional shape 136 are displaced relative to each other, the blade indentation 126 and the socket indentations 130 need not be provided directly opposite each other. Instead the blade indentation 126 and the socket indentations 130 may be displaced the same amount relative to each other, as the first cross-sectional shape 134 and the second cross-sectional shape 136 are displaced relative to each other.

Claims

An axial fan (100) comprising a hub (102) and a plurality of blades (104) each of which extends away from the hub (102),
wherein each blade (104) defines a blade air moving part (112) which during rotation of the axial fan (100) causes air to be moved relative to the axial fan, and a blade retaining part (114);
wherein the hub (102) defines a plurality of hub retaining sockets (108) each of which is adapted to retain a blade radially by engagement between the hub retaining socket (108) and the respective blade retaining part (114);
wherein each blade retaining part (114) on an outer surface defines a plurality of blade indentations (126) with a first cross-sectional shape, and wherein each hub retaining socket (108) on an inner surface defines a plurality of socket indentations (130) with a second cross-sectional shape,
wherein provision of a pitch determining element (124) in one blade indentation (126) and in one socket indentation (130) causes the blade (104) to be retained at a predetermined pitch angle relative to the hub (102),
characterised in that the pitch determining element (124) is non-cylindrical, and wherein the cross-sectional shape of the pitch determining element (124) corresponds to that of two semi-circles which are displaced relative to each other.
An axial fan (100) according to claim 1, wherein the cross-sectional shape of the pitch determining element (124) corresponds at least to that of the first and second cross-sectional shape.
An axial fan (100) according to any of the preceding claims, wherein the cross-sectional shape of the pitch determining element (124) is non-symmetrical.
An-axial fan (100) according to any of the preceding claims, wherein each of the first cross-sectional shape and the second cross-sectional shape defines a semi circle.
An axial fan (100) according to any of the preceding claims, wherein the hub retaining socket (108) defines two half parts each with a substantially semi-circular cross-section.
An axial fan (100) according to any of the preceding claims, wherein the hub (102) defines a proximal hub part (106) which defines a plurality of hub retaining sockets (108) and a distal hub part (110) which defines the same number of hub retaining sockets (108).
An axial fan (100) according to any of the preceding claims, wherein the proximal hub part (106) and the distal hub part (110) are fastened to each other such that the plurality of circular cross-sections are defined.
A blade (104) for an axial fan (100) according to any of claims 1-7.
A hub (102) for an axial fan (100) according to any of claims 1-7.
A pitch defining element (124) according to any of claims 1-7.
A kit comprising a hub (102) and plurality of blades (104) and a plurality of pitch determining elements (124) according to any of claims 1-7.
A kit according to claim 11, further comprising a pitch determining element (124') with a circular cross-section.
A kit according to claim 12, wherein the pitch determining element (124') with the circular cross-section is cylindrical