WO2014079864A1

WO2014079864A1 - A cooling system and an axial fan for a cooling system

Info

Publication number: WO2014079864A1
Application number: PCT/EP2013/074257
Authority: WO
Inventors: Victor SILBERMAN; Antoni Hendrik STANNOV
Original assignee: Multi-Wing International A/S
Priority date: 2012-11-20
Filing date: 2013-11-20
Publication date: 2014-05-30

Abstract

The invention provides a cooling system for a combustion engine. The system comprises an orifice plate and an axial fan arranged at least partly within an orifice of the orifice plate. The axial fan comprises a hub being adapted for rotation about an axis and carrying a plurality of blades, each blade extending radially between opposite ends, one end being joined with the hub and the other end forming a tip edge. The tip edge comprises a first portion extending from a leading edge of the blade to a radial step, and a second portion extending from the radial step to a trailing edge of the blade. The distance from the axis to the second portion of the tip edge is smaller than the distance from the axis to the first portion of the tip edge. Furthermore, the cooling system comprises brushes extending radially outwards from the second portion towards the orifice plate.

Description

A COOLING SYSTEM AND AN AXIAL FAN FOR A COOLING SYSTEM Field of the invention

The present invention relates to a cooling system for a combustion engine. The cooling system comprises an orifice plate and an axial fan. The axial fan comprises a hub being adapted for rotation about an axis and carrying a plurality of blades extending radially between opposite ends, one end is joined with the hub and the other end forms a tip edge.

Background of the invention

Traditionally, an axial fan and an orifice plate are mounted at each their chassis whereby they can move independently of each other. To ensure that the blades are not damaged during rotation of the hub, the blades and the orifice plate is traditionally mounted with a clearance between the tip edge and the orifice plate. The clearance is necessary due to vibrations and tolerances. However, this clearance distance increases aerodynamic losses and reduces performance.

Description of the invention It is an object of embodiments of the invention to provide an improved cooling system for a combustion engine.

It is a further object of embodiments of the invention to provide a cooling system which reduces aerodynamic losses.

According to a first aspect, the invention provides a cooling system for a combustion engine, the system comprising an orifice plate and an axial fan arranged at least partly within an orifice of the orifice plate, the axial fan comprising a hub being adapted for rotation about an axis and carrying a plurality of blades, each blade extending radially between opposite ends, one end being joined with the hub and the other end forming a tip edge, the tip edge comprising a first portion extending from a leading edge of the blade to a radial step, and a second portion extending from the radial step to a trailing edge of the blade, wherein the distance from the axis to the second portion of the tip edge is smaller than the distance from the axis to the first portion of the tip edge, the cooling system further comprises brushes extending radially outwards from the second portion towards the orifice plate. In the context of the present invention, the term 'axial fan' should be understood as, a fan which is adapted to move gas, typically air, in a direction parallel with the rotation axis of the fan. The direction of the air flow may comprise a radial component, so that axial fans also comprises so called mixed flow fans, i.e. a fan having an air flow with an axial and a radial component. Herein 'air' should be understood as covering any gas, so that 'air flow' in the present invention covers a flow of gas.

The axial fan according to the present invention is used for cooling of a combustion engine. The combustion engine may e.g. form part of a tractor, or a combine harvester or any similar kind of agricultural machinery, or an excavator, a bulldozer, a crane, or any similar kind of construction equipment for on-highway or off-highway usage.

The hub will typically be connected to an axle which is rotated by the combustion engine via a belt or driven by an electrical driven motor or a hydraulic driven motor. The rotation causes rotation of the hub and thereby movement of air. In air cooled combustion engines the air cools an outer surface of the combustion engine, and in water cooled engines, the air is blown through a radiator which cools the cooling liquid. This axle may be an axle which forms an extension of the axle of the combustion engine.

The blades may be formed in one part with the hub, or each blade may be formed as separate components which are attached to a hub. The blades may be detachably attached to the hub. In one embodiment, the hub and the blades are designed such that the pitch of the blade may be set in connection with the attachment of the blade to the hub. In this embodiment, the pitch of the blades may be changed by disconnecting the blades from the hub or by loosening the joint between the hub and the blades, and subsequently attaching or fastening the blades to the hub at a new pitch angle. The hub and/or the blades may as an example be made from a metal material, plastic material, or from a composite material comprising fibres e.g. of glass or carbon. Different examples are iron, aluminium, polycarbonate, polystyrene, polytetrafluoroethylene, polyamid, polypropolene, or vinyl etc. It will be appreciated that other metals or plastic materials 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

circumferentially along an outer surface of the hub. The blades may, however, also be arranged asymmetrically along an outer surface of the hub. The length of the blades may be in the range 100-750 millimetres, such as 100 millimetres, such as 250 millimetres, such as 500 millimetres, such as 750 millimetres. The size of the fan along the axial direction may be in the range of 30-400 millimetres.

Each blade may define an attachment part and an air moving part. In embodiments, where the blades are detachably attached to the hub, the attachment part is that part of the blade which is attached to the hub. In embodiments where the blades and the hub form an integral element, the attachment part shall be construed as the transition between the blade and the hub.

During operation of the cooling system, the axial fan and the orifice plate may move and/or vibrate independently of each other as they may be mounted at each their chassis. During operation of the fan, air is moved through the orifice of the orifice plate. The orifice plate may be a metal plate, such as a steel plate, in which an orifice is e.g. cut or stamped. In this embodiment, the radial inwards edge of the orifice, in the following denoted "the orifice edge" is defined by the thickness of the orifice plate, also denoted the depth of the orifice plate. Since the axial fan is located at least partly in the orifice, the orifice edge is typically directly adjacent the tip edge.

In the following, we will use the term "depth" to describe the dimension of the orifice edge and the tip edge in the axial direction. Typically, the depth of the orifice edge is much smaller than the depth of the tip edge. The orifice edge may e.g. have a depth of 5-30 percent of the depth of the tip edge, such as 10-20 percent of the depth of the tip edge.

In the context of the present invention, the term leading edge shall be understood as the foremost part of the blade. Similarly, the term trailing edge designates the rearmost part of the blade. The tip edge of the blades extends from the leading edge to the trailing edge at the tip end of the blade. The blades of the present invention comprise a tip edge which comprises a first portion extending from the leading edge of the blade to a radial step, and a second portion extending from the radial step to the trailing edge of the blade, wherein the distance from the axis to the second portion is smaller than the distance from the axis to the first portion. Thus, a larger clearance distance between the tip end of the blades and the orifice plate may be provided at the second portion, whereas the clearance distance between the tip end of the blades and the orifice plate at the first portion may be smaller. As the axial fan is arranged at least partly within an orifice of the orifice plate, i.e. so that an overlap along the axial direction exists between the blades and the orifice plate, this overlap may advantageously be positioned within the second portion so that the risk of impact between the blades and the orifice plate can be avoided or at least considerably decreased while the radial size of the first portion is larger and thereby comes closer to the orifice edge.

The cooling system further comprises brushes extending radially outwards from the second portion towards the orifice plate, whereby the brushes may reduce leakage between the tip end of the blade and the orifice plate or even seal a gap between the second portion and the orifice plate. Thereby aerodynamic losses can be minimized and a higher performance may be ensured.

Since the cooling system is particularly suitable for combustion engines in construction equipment, the brushes may prevent dirt and mud from being deposited on the orifice edge, and the brushes may reduce noise, particularly noise which may result from periodic contact between the blades and the orifice plate during rotation. The brushes may include fibres of a plastic material, such as different polyamides, e.g. PA6, Nylon, or Kevlar, or from polyester. As an alternative, the brushes may include fibres of carbon or various natural fibres, e.g. fibres from plants.

In one embodiment, the brush may be sized such that it provides contact between the blade and the orifice edge. In this embodiment, the brush may include fibres of an electrically conductive material thereby providing electrical conductivity between the axial fan and the orifice plate.

The length of the brushes is herein defined as the dimension in radial direction, i.e. from the edge of the second section to the free end of the brushes. To minimize the aerodynamic losses the length of the brushes may be in the range of the size of the step, whereby the free end of the brushes forms a substantially straight line forming an extension of the edge of the first section. In an alternative embodiment, the free end of the brushes extends past the edge of the first section, whereby the brushes may be close to the orifice plate or even in contact with the orifice plate, so that the brushes may close the gap between the blade and the orifice plate. By providing the length of the brushes so that the brushes do not contact the orifice plate, but so that the gap is sealed, i.e. without a clearance distance, performance of the fan may be enhanced, and additionally noise may be reduced.

The first portion may constitute in the range of 45-90 percent of the tip edge, resulting in a second potion constituting in the range of 10-55 percent. The length of the first and second sections, respectively, may depend on the combustion engine to be cooled, the size of the hub, the length of the blades, the diameter of the orifice opening, etc.

A projection of the second portion in a direction along the axis may have a length in the range of 5-60 percent of a projection of the tip edge in a direction along the axis, where the projection of the tip edge corresponds to the projected chord length which is substantially equal to the depth of the fan along the rotation axis.

The radial step may be in the range of 0.5-4.0 percent, such as in the range of 1.0-3.0 percent, such as in the range of 1.5-2.5 percent of the distance from the axis to the first portion. As an example, the step may be approximately 8 millimetres at a blade having a radial distance from the axis to the first portion of 298 mm, i.e. having a step of approximately 2.7 percent. This fan may be arranged partly within an orifice having a diameter of 600 millimetres, leaving a clearance distance of approximately 2 millimetres. In a traditional cooling system , the corresponding clearance distance would typically be approximately 10 millimetres, resulting in considerably higher aerodynamic losses.

As the brushes may be worn during use, the brushes may be detachably attached in order to enable replacement hereof. To enable replacement of the brushes, the brushes and the blades may comprise concurrent structures enabling attachment and release of the brushes to and from the blades. The concurrent structure of the brushes may form part of an attachment part of the brushes.

Particularly, the concurrent structures may enable release and attachment of the blades without having to remove the axial fan from the orifice plate. This may be enabled by concurrent structures facilitating removal and attachment of the brushes by movement of the brushes relative to the blades along the rotation axis, i.e. in the axial direction. Particularly, the brushes may be removable or attachable from the trailing edge in the direction away from the first portion of the tip edge.

In one embodiment, the concurrent structures comprise a protrusion and an indentation, so that the protrusion of the blade or on the attachment part of the brushes may be inserted into the indention of the other one of the blade and the attachment part of the brushes. The indentation may form a through hole. If the protrusion is formed with an extension part, e.g. at the end of the protrusion, the extension having a larger diameter than the rest of the protrusion, this extension part may be press-fitted into a cavity of the indentation or through the indentation thereby enabling a press-fit coupling between the blade and the brushes. As an alternative, the concurrent structures may comprise a track and an insert member to facilitate guided relative movement during attachment of the brushes to the blades. The attachment part of the brushes may comprise a track which allows the brushes to be slit and thus guided along the second section and thereby allowing for attachment hereof, as the blade along the second section may comprise an insert member forming part of the blade, which insert member fits into the track.

As a further alternative, the brushes may be bonded to the blade by bonding the attachment part of the brushes to the blade.

To protect the brushes during operation of the fan, a resilient profile may be attached to the orifice plate along the edge of the orifice for protection of the brushes during rotation of the hub. The resilient profile may particularly cover the orifice edge. This may prolong the lifespan of the brushes. The resilient profile may e.g. comprise a low friction material, e.g. including Polytetrafluoroethylene (PTFE) or vinyl.

As an alternative a second brush may be attached along the edge of the orifice, e.g. to the orifice edge, as this second brush may both add to the sealing of the gab and protect the brushes attached to the second portion.

According to a second aspect, the invention provides an axial fan for cooling of a combustion engine, the fan comprising a hub being adapted for rotation about an axis and carrying a plurality of blades, each blade extending radially between opposite ends, one end being joined with the hub and the other end forming a tip edge, the tip edge comprising a first portion extending from a leading edge of the blade to a radial step, and a second portion extending from the radial step to a trailing edge of the blade, wherein the distance from the axis to the second portion of the tip edge is smaller than the distance from the axis to the first portion of the tip edge, the fan further comprises brushes extending radially outwards from the second portion.

It should be understood, that a skilled person would readily recognise that any feature described in combination with the first aspect of the invention could also be combined with the second aspect of the invention, and vice versa.

The axial fan according to the second aspect of the invention is very suitable for the cooling system according to the first aspect of the invention. The remarks set forth above in relation to the cooling system are therefore equally applicable in relation to the axial fan. According to a third aspect, the invention provides a cooling system for a combustion engine, the system comprising an orifice plate and an axial fan arranged at least partly within an orifice of the orifice plate, the axial fan comprising a hub being adapted for rotation about an axis and carrying a plurality of blades, each blade extending radially between opposite ends, one end being joined with the hub and the other end forming a tip edge, the tip edge comprising a first portion extending from a leading edge of the blade to a radial step, and a second portion extending from the radial step to a second radial step, and a third portion extending from the second radial step to the trailing edge of the blade, wherein the distance from the axis to the second portion of the tip edge is smaller than the distance from the axis to the first portion of the tip edge, the cooling system further comprises brushes extending radially outwards from the second portion towards the orifice plate.

The distance from the axis to the third portion of the tip edge may equal the distance from the axis to the first portion of the tip edge. However, in an alternative embodiment, the distance from the axis to the third portion of the tip edge and the distance from the axis to the first portion of the tip edge may be different.

It should be understood, that a skilled person would readily recognise that any feature described in combination with the first aspect of the invention could also be combined with the third aspect of the invention, and vice versa.

Brief description of the drawings Embodiments of the invention will now be further described with reference to the drawings, in which:

Fig. 1 illustrates a cross-section through a fan and an orifice plate along the rotation axis of the fan,

Fig. 2 illustrates a projection of the step relative to a projection of the tip end, Figs. 3-5 illustrate different ways of attaching the brushes to the blades, and Fig. 6 schematically illustrates an alternative embodiment of a blade. Detailed description of the drawings

It should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Fig. 1 illustrates a cooling system 1 for a combustion engine (not shown). The cooling system 1 comprises an orifice plate 2 and an axial fan 3 arranged at least partly within an orifice 4 of the orifice plate 2.

The axial fan 3 comprises a hub 5 being adapted for rotation about an axis illustrated by the dotted line 6 and carrying a plurality of blades 7 of which two is shown. Each blade 7 extends radially between opposite ends, one end being joined with the hub 5 and the one end forming a tip edge 8.

The tip edge 8 comprises a first portion 8a extending from a leading edge 9 of the blade 7 to a radial step 10, and a second portion 8b extending from the radial step 10 to a trailing edge 11 of the blade 7. The distance L2 from the axis 6 to the second portion 8b of the tip edge 8 is smaller than the distance L1 from the axis 6 to the first portion 8a of the tip edge 8.

The cooling system 1 further comprises brushes 12 extending radially outwards from the second portion 8b towards the orifice plate 2.

The axial fan 3 is used for cooling of a combustion engine (not shown). The combustion engine may form part of construction equipment. The fan 3 is adapted to move air in a direction parallel with the rotation axis 6 of the fan as indicated by the arrow 13. During operation of the fan 3, air is moved through the orifice 4 of the orifice plate 2.

The axial fan 3 is arranged partly within the orifice 4 of the orifice plate 3, so that an overlap O along the axial direction exists between the blades 7 and the orifice plate 2. In the illustrated embodiment the fan 3 is arranged flush with the orifice plate 2, so that the overlap O corresponds to the thickness of the orifice plate 2. This overlap O is positioned within the second portion 8b so that the risk of impact between the blades 8 themselves and the orifice plate 2 can be avoided or at least considerably decreased. A potential impact would be impact between the orifice plate 2 and the brushes 12. The length L of the brushes 12 in the radial direction equals in the present embodiment the size of the step L3. Due to the radial step 10 and the brushes 12, the clearance distance L4 between the tip edge 8 and the orifice 4 may be smaller than in a traditional fan. The brushes 12 can reduce leakage between the tip end 8 of the blade 7 and the orifice plate 2 by substantially sealing a gap 14 between the second portion 8b and the orifice plate 2, whereby aerodynamic losses can be minimized and a higher performance ensured.

In the illustrated embodiment, the step L3 is approximately 8 millimetres. The radial distance L1 from the axis to the first portion is approximately 298 mm, whereas the radial distance L2 from the axis to the second portion is approximately 290 mm. The fan 3 is arranged partly within an orifice 4 having a diameter of 600 millimetres, leaving a clearance distance L4 of approximately 2 millimetres. In a traditional cooling system, the corresponding clearance distance would typically be approximately 10 millimetres, resulting in considerably higher aerodynamic losses.

Fig. 2 illustrates a comparison between projections of the radial step 10 and the tip end 8. The length L of the radial step and the chord length LC of the tip edge 8 are projected in a direction along the rotation axis and the air movement direction 13. In the illustrated embodiment, the projected step length PL is approximately 40 percent of the projected chord length PLC.

Figs. 3-5 illustrate different ways of attaching the brushes 12 to the blades 7. As the brushes 12 may be worn during use, the brushes 12 can be detachably attached in order to enable replacement hereof.

To enable replacement of the brushes 12, the brushes 12 and the blades 7 may comprise concurrent structures 14, 15 as illustrated in Figs. 3 and 4, thereby enabling attachment and release of the brushes 12 to and from the blades 7. The brushes 12 illustrated in Figs. 3-5 comprises an attachment part 16 at which the brushes 12 are attached and which enables attachment of the brushes 12 to the blades 7. The concurrent structure 14, 15 of the brushes 12 forms part of the attachment part 16.

In the embodiment illustrated in Fig. 3, the concurrent structures 14 comprise two protrusions 14a at the attachment part 16 and two indentations 14b of the blades, so that the protrusions 14a can be inserted into the indentions 14b. As illustrated, the indentations 14b form through holes. The protrusions 14b are formed with an extension part 17 at the free end of the protrusions 14b, the extensions 17 having a larger diameter than the rest of the protrusions 14b, whereby the extensions 17 may be press-fitted through the indentations 14b so that the extensions 17 extend on the other side of the blade, thereby enabling a press-fit coupling between the blade 7 and the brushes 12. Fig. 4 illustrates an alternative embodiment, where the concurrent structures 15 comprise a track 15a and an insert member 15b to facilitate guided relative movement of the brushes 12 and the blades 7 during attachment of the brushes 12 to the blades 7. The attachment part 16 of the brushes comprises a track 15a which allows the brushes 12 to be slit and thus guided along the second section 8b and thereby allows for attachment hereof, as the blade 7 along the second section 8b may comprise an insert member 15b forming part of the blade 7, which insert member 15b fits into the track 15a. Furthermore, the blades 7 comprise two through holes (not shown) through which a locking part 15c is inserted thereby preventing unwanted relative movement between the blades 7 and the brushes 12 during operation of the fan 3.

In the further alternative embodiment illustrated in Fig. 5, the brushes 12 are bonded to the blade 7 by bonding the attachment part 16 of the brushes 12 to the blade 7 by use of an adhesive 17. To replace the brushes 12, a solvent has to be used.

Fig. 6 schematically illustrates an alternative embodiment of a blade for a cooling system, where the blade 7' extends radially between opposite ends, one end being joined with the hub and the other end forming a tip edge. The tip edge comprises a first portion 8a' which extends from a leading edge 9' to a radial step 10', and a second portion 8b' which extends from the radial step 10' to a second radial step 10", and a third portion 8c which extends from the second radial step 10" to the trailing edge 11 '. The distance from the axis (not shown) to the second portion 8b' of the tip edge is smaller than the distance from the axis to the first portion of the tip edge 8a'. Whereas the distance from the axis to the third portion 8c of the tip edge equals the distance from the axis to the first portion 8a' of the tip edge.

Brushes 12' extend radially outwards from the second portion 8b' towards the orifice plate (not shown) .

Claims

CLAI MS

1. A cooling system for a combustion engine, the system comprising an orifice plate and an axial fan arranged at least partly within an orifice of the orifice plate, the axial fan comprising a hub being adapted for rotation about an axis and carrying a plurality of blades, each blade extending radially between opposite ends, one end being joined with the hub and the other end forming a tip edge, the tip edge comprising a first portion extending from a leading edge of the blade to a radial step, and a second portion extending from the radial step to a trailing edge of the blade, wherein the distance from the axis to the second portion of the tip edge is smaller than the distance from the axis to the first portion of the tip edge, the cooling system further comprises brushes extending radially outwards from the second portion towards the orifice plate.

2. A cooling system according to claim 1 , wherein the brushes are detachably attached.

3. A cooling system according to claim 1 or 2, wherein the first portion constitutes in the range of 45-90 percent of the tip edge.

4. A cooling system according to any of the preceding claims, wherein a projection of the second portion in a direction along the axis has a length in the range of 5-60 percent of a projection of the tip edge in a direction along the axis.

5. A cooling system according to any of the preceding claims, wherein the radial step is in the range of 0.5-4.0 percent of the distance from the axis to the first portion.

6. A cooling system according to any of the preceding claims, wherein a length of the brushes is in the range of the size of the step.

7. A cooling system according to any of claims 1 -5, wherein a length of the brushes is larger than the size of the step.

8. A cooling system according to any of the preceding claims, wherein the brushes and the blades comprise concurrent structures enabling attachment of the brushes to the blades.

9. A cooling system according to claim 8, wherein the concurrent structures comprise a protrusion and an indentation.

10. A cooling system according to claim 8, wherein the concurrent structures comprise a track and an insert member to facilitate guided relative movement during attachment of the brushes to the blades.

11. A cooling system according to any of the preceding claims, wherein a resilient profile is attached to the orifice plate along the orifice for protection of the brushes during rotation of the hub.

12. An axial fan for cooling of a combustion engine, the fan comprising a hub being adapted for rotation about an axis and carrying a plurality of blades, each blade extending radially between opposite ends, one end being joined with the hub and the other end forming a tip edge, the tip edge comprising a first portion extending from a leading edge of the blade to a radial step, and a second portion extending from the radial step to a trailing edge of the blade, wherein the distance from the axis to the second portion of the tip edge is smaller than the distance from the axis to the first portion of the tip edge, the fan further comprises brushes extending radially outwards from the second portion.

13. A cooling system for a combustion engine, the system comprising an orifice plate and an axial fan arranged at least partly within an orifice of the orifice plate, the axial fan comprising a hub being adapted for rotation about an axis and carrying a plurality of blades, each blade extending radially between opposite ends, one end being joined with the hub and the other end forming a tip edge, the tip edge comprising a first portion extending from a leading edge of the blade to a radial step, and a second portion extending from the radial step to a second radial step, and a third portion extending from the second radial step to the trailing edge of the blade, wherein the distance from the axis to the second portion of the tip edge is smaller than the distance from the axis to the first portion of the tip edge, the cooling system further comprises brushes extending radially outwards from the second portion towards the orifice plate.