GB2597957A

GB2597957A - Improvements in and to power tools

Info

Publication number: GB2597957A
Application number: GB2012500.1A
Authority: GB
Inventors: Rees Samuel; Liard Price Steven
Original assignee: Evolution Power Tools Ltd
Current assignee: Evolution Power Tools Ltd
Priority date: 2020-08-11
Filing date: 2020-08-11
Publication date: 2022-02-16
Also published as: GB202012500D0; GB2598046A

Abstract

A power tool comprises a housing and a motor 2000, where the motor powers a drive shaft 2001, vacuum generator 2002 and motor cooling fan 2008. The suction generator has a first fluid flow in a first direction which substantially opposes the second fluid flow of the cooling fan in a second direction. The flows may exit the housing through a common exhaust. The vacuum generator and cooling fan may form a single fan unit, which could have a two-part housing. The fluid flow generator may comprise one or two discs 2003, 2009 which include vacuum generating vanes 2005 and cooling fluid flow generating blades 2010. The power tool may include integrated ducting with a debris collection passage, where dust generated by the tool is sucked up through an inlet and channelled to a collector. A method of assembling the vacuum generator within the power tool is also envisaged.

Description

POWER TOOL WITH INTEGRAL VACUUM

Field of the Invention

[0001] The present invention relates to a power tool comprising an integral 5 vacuum generator; a method of assembling the same and a fluid flow generator for a power tool.

Backdround of the Invention [0002] Power tools normally generate debris in use by the removal of excess material from a substrate being worked upon.

[0003] Typically such debris is collected once work has finished, such as by dustpan and brush or via an external vacuum cleaner at a later date. By this point the debris has already caused a mess and despite thorough efforts of the cleaner some debris will remain in the surrounding environment.

[0004] Efforts have therefore been made to adapt power tools to collect debris as a substrate is being worked in order to minimize the clean-up required afterwards. Such attempts normally use the inherent inertia of the debris as it is generated by the power tool with collectors arranged to catch the debris in flight.

These systems are inefficient and lead to cross contamination of the fluid originating from the debris collection channel being carried into the cooling fan. This causes debris to unnecessarily enter the motor housing and hinder the efficiency of the tool or foul the work area.

[0005] Alternatively, a separate vacuum system may be rigged up to suck up debris as it is generated. Such systems are bulky requiring a user to transport and arrange a vacuum cleaner cluttering the work area. The addition of trailing cables and ducting increases the risks of using the tool such as trip hazards and the risk of cutting through electrified cables.

[0006] There is therefore a need for a powered tool which addresses these problems.

[0007] Manufacturing a powered tool with integrated vacuum components is also inefficient and typically requires a multi-stage assembly process, involving first the assembly of the power tool and then second the assembly of a vacuum generator, for example a vacuum fan. This multi-part assembly requires the corresponding addition of specific hardware or an access window to permit the vacuum fan components to be retrospectively fitted to the tool. Known methods of introducing a vacuum component into a power tool include installing the vacuum fan on to drive shaft of an already assembled power tool a process which may require additional fasteners e.g. collars, grub screws or shims. The addition of this extra hardware increases the complexity of the manufacturing process and the number of pieces required for the assembly. These additional fastening components routinely require access for a tool to be able to tighten or loosen the vacuum fan components. Consequently, such designs are provided with access hatches, holes, ports or panels, which may be exposed or open. The presence of an exposed opening with fastener components near a high-speed spinning shaft is a particular safety concern. Furthermore, such access panels also add extra components and increases the noise of the tool, reduce the balance of the tool and alter the airflow around the tool such that the airflow is imperfect and the tool efficiency is reduced. Therefore, there is a need for an improved method of constructing a power tool with an integrated vacuum fan which does not the separate assembly of the power tool and vacuum components during manufacture; and which does not have the aforementioned problems. The completed assembly must be dynamically balanced to work properly without becoming unbalanced, making noise, having reduced efficiency, risk of components falling out or posing a safety hazard.

Summary of the Invention

[0008] According to a first aspect there of the present invention, there is provided a power tool comprising: a housing; a motor located within the housing; a vacuum generator; a cooling fan; and a drive shaft for a powered tool; the motor providing driving power to said drive shaft, said vacuum generator and said cooling fan; wherein the vacuum generator has a first fluid flow in a first direction and the cooling fan has a second fluid flow in a second direction and said first and second directions are substantially opposing directions relative to one another.

[0009] Preferably, the vacuum generator and cooling fan comprise a single fan unit having a motor and at least one vacuum generating vane arranged on a first disc face which constitutes a vacuum generator and at least one cooling fluid flow generating vane on a second face of the same disk. It is envisaged that the vacuum generator and the cooling fan are integral with the power tool's electric motor.

[0010] It is envisaged that the cooling fan is arranged to cool said motor located within said housing.

[0011] Advantageously by having the motor providing driving power to both the powered tool and the vacuum generator, only a single motor is required for full operation of the power tool. This simplifies the tool design as a single drivetrain is required (rather than a separate drive systems being required for each of the powered tool and the vacuum generator). The motor can therefore power the powered tool, vacuum generator, and cooling fan simultaneously. No separate suction fan driving system is needed (i.e. an additional motor over the motor).

[0012] Suitably the housing comprises integral ducting providing a debris collection channel. By designing the housing to comprise integral pre-formed channels (e.g. by forming a duct via injection moulding, die casting, or other manufacturing process when the housing is formed) the power tool construction is simplified, and fewer parts are required (i.e. there is no requirement for a separate tubular duct or pipe).

[0013] The housing is typically a multiplicity of parts which may be an arrangement of channels, a set of ducts, a set of pathways or conduits. Alternatively, the housing may be an arrangement of channeling components. As the housing is a complex structure is it possible to build in extra, secondary functions and features in the design process. Preferably, the housing comprises integral ducting formed from two half-channels in a two-part form, said two half-channels being combined to form an integral duct once combined [0014] Preferably the debris collection channel is arranged to collect debris generated by the powered tool and channel the debris to the vacuum generator for deposition in a debris collector without additional parts. The debris collection channel therefore forms a complete pathway from the point where the debris is generated (i.e. at the powered tool), through the tool housing, past the vacuum generator and to a collector.

[0015] Advantageously the housing further comprises integral cooling ducting arranged to channel a cooling fluid over the motor thereby negating the need for cooling channels which are separate pieces. The cooling channels are formed within the housing itself at the point of manufacture simplifying power tool construction.

[0016] Preferably the vacuum generator and cooling fan urge the fluid flows in substantially opposing directions relative to one another. Opposing will be understood to be two counter directions and includes substantially opposing flow i.e. any first fluid flow which is not in the same direction as the second fluid flow.

Thus, opposing flow may also be understood to include: divergent flow, separate flow, contrasting flow, alternative flow, diametrical flow and co-operating but different flow. The vacuum generator and cooling fan may have fluid flows arranged to converge at an angle of typically 900 with respect to one another. However, it will be understood that the cooling flow and vacuum air flow may converge at any angle in within the range of 300-2700 with respect to one another, or may even be parallel to one another.

[0017] By urging the fluid flow in substantially opposing directions relative to one another the contents of one fluid is less likely to contaminate the second fluid (e.g. by debris carried by the fluid originating from the debris collection channel being carried by the fluid originating from the cooling fan). This prevents debris entering the motor housing. It will be readily understood that the term opposing refers to a first and second fluid flow each travelling in different directions and includes substantially opposing flow i.e. any first fluid flow which is not in the same direction as the second fluid flow.

[0018] Suitably the fluids having substantially opposing directions relative to one another leave the housing at a common exhaust. While the fluids have substantially opposing directions within the power tool housing, towards the common exhaust the direction of travel of both fluids are aligned and channelled to a common exhaust. This negates the need for a second separate exhaust. The direction of travel of fluids is only aligned once contamination of both fluids by debris is safe and unlikely to foul other parts of the power tool such as the motor.

[0019] Advantageously the fluids having substantially opposing directions relative to one another flow in substantially partitioned ducting wherein a first fluid is a clean fluid relative to an at least second dirty fluid. The clean fluid can be used to cool sensitive internal components of the power tool such as a the motor without causing the parts to become fouled by debris and dust which is carried in a second separate fluid flow by the dirty fluid.

[0020] Preferably the integral ducting comprises an inlet, the inlet being adjacent a powered tool. Arranging the inlet adjacent the powered tool provides the greatest chance for any dust and debris generated by the powered tool in use to be urged into the debris collection channel and to the debris collector.

[0021] According to a second aspect of the present invention there is provided a fluid flow generator for a power tool comprising: a disc having; at least one vacuum generating vane on a first face; and at least one cooling fluid flow generating vane on a second face; wherein; the at least one vacuum generating vane arranged on the first disc face constitutes a vacuum generator; and the at least one cooling fluid flow generating vane arranged on the second disc face constitutes a cooling fan.

[0022] Advantageously, the generation of the cooling and vacuum fluid flows may be affected by a single part, negating the need to separate vacuum and cooling fans, simplifying construction and improving durability.

[0023] Suitably the at least one vacuum generating vane is further connected to a face of a second disc such that the first disc and second disc are spaced apart by the at least one vacuum generating vane, the second disc comprising an inlet arranged towards a disc hub of the second disc and an outlet, provided towards a disc rim of the second disc. This forms a centrifugal fan. Debris enters the centrifugal fan through a hub-facing aperture and is then directed to the exterior fan rim. This increases the velocity of the debris and urges the debris onward from the centrifugal fan towards the debris collector. The integral ducting of the fan comprises a curved funnel or scroll, which may also be referred to as a volute. The scroll portion of the integral housing received the fluid being pumped into the housing by the rotor. The scroll increases in area as it approaches the exhaust or discharge port of the power tool. The curved funnel or scroll portion of the fan housing receives fluid or air from the inlet and maintains the flow of debris and cooling airflow toward the exhaust. As fluid is received from the rotor and travels though the scroll, the increasing area of the scroll amplifies the velocity of the fluid flow as it progresses to the exhaust. As fluid flow progresses through the scroll it is joined by further fluid flow from the rotor within the housing and as the cross-sectional area of the scroll increases the velocity is maintained. If the flow rate falls, then velocity will decrease across the scroll; consequentially, the pressure of the fluid flow will rise. Thus, the scroll assists in pressurising and maintaining the flow of debris and cooling airflow.

[0024] Preferably, the at least one vacuum generating vane and the at least one cooling fluid vane are arranged to urge fluid flow in substantially opposing directions relative from one fluid to another. In this arrangement a single fan unit device is capable of both generating a vacuum as the vacuum generation means, and generating a cooling fluid generator as the cooling fan. A fan unit will be understood to comprise a vacuum fan and a cooling fan. Preferably, the fan unit has an integrated vacuum fan and cooling fan where the fluid flow of said vacuum fan is in an opposite direction to the fluid flow of the cooling fan.

[0025] Preferably, motor of the power tool is capable of powering both the vacuum fan and the cooling fan. A groove in the fan body separates the respective vacuum and cooling components of the fan assembly and a diaphragm located in the groove prevents the 'dirty' air sucked up by the vacuum from contaminating the 'clean' air pulled into the cooling side of the fan.

[0026] Advantageously, the vacuum generator and the cooling fan share a common fan housing which is split into at least first (front) and second (back) parts. This split housing allows the fan to be easily installed in one piece during manufacture without the need for additional hardware or without splitting the fan into its two respective vacuum and cooling components.

[0027] This split fan housing enables the power tool to be tooled more efficiently and prevents the need to separately assemble the vacuum and cooling fan components. The split fan housing advantageously enables alternative methods of manufacture for example 3D printing and/or any other form of additive manufacturing process in which computer-aided design may be used to instruct hardware to deposit material to create a precisely shaped object.

[0028] This optimised method of manufacture requires fewer components than an assembly comprising separate vacuum and cooling fans. It is a further advantage of the new method of manufacture that the split housing enables features such as: cylindrical fan forms, bumps, and grooves and undercut shapes to be tightly enclosed to work effectively, to maintain close tolerances and fits, prevent air leaks and retain a production-ready assembly method. Such a tight enclosure would not have been permitted by known manufacturing methods which required access hatches, apertures or other methods.

[0029] Other aspects are as set out in the claims herein.

Brief Description of the Drawings

[0030] For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which: [0031] Figure 1 is a side view of a power tool in upper cutting head position.

[0032] Figure 2 is a front view of a power tool in lowered cutting head position [0033] Figure 3 is a top view of a power tool in lowered cutting head position.

[0034] Figure 4 is a cross section through the motor housing of a power tool.

[0035] Figure 5 is a cross section through the cooling fan of a power tool [0036] Figure 6 is a cross section through the vacuum generator of a power tool.

[0037] Figure 7 is a first view of the motor and fan assembly of a power tool in accordance with a first embodiment of the present invention.

[0038] Figure 8 is a second view of the motor and fan assembly of a power tool in accordance with a first embodiment of the present invention.

[0039] Figure 9 is a front perspective view of the motor and fan assembly of a power tool in accordance with a second embodiment of the present invention.

[0040] Figure 10 is a third view of the motor and fan assembly of a power tool in accordance with a second embodiment of the present invention.

[0041] Figure 11 is a fourth view of the motor and fan assembly of a power tool in accordance with a second embodiment of the present invention.

[0042] Figure 12 is a fifth view of the motor and fan assembly of a power tool in accordance with a second embodiment of the present invention.

[0043] Figure 13 is a sixth view of a typical example of a motor armature and fan assembly of a power tool in accordance with a second embodiment of the present invention.

[0044] Figure 14 is a view of a typical example of a motor armature and fan assembly of a power tool in accordance with a second embodiment of the present invention, absent of the motor stator.

[0045] Figure 15 is a second view of a typical example of a motor armature and the fan assembly of a power tool in accordance with a second embodiment of the present invention, absent of the motor stator.

[0046] Figure 16 is a third view of a typical example of a motor armature and fan assembly of a power tool in accordance with a second embodiment of the present invention, absent of the motor stator.

[0047] Figure 17 is a fourth view of a typical example of a motor armature and fan assembly of a power tool in accordance with a second embodiment of the present invention, absent of the motor stator.

[0048] Figure 18 is a fifth view of the motor and fan assembly of a power tool in accordance with a second embodiment of the present invention, absent of the motor stator.

[0049] Figure 19 is a first perspective view of the integral vacuum generator and cooling fan in accordance with a second embodiment of the present invention.

[0050] Figure 20 is a second perspective view of the integral vacuum 15 generator and cooling fan in accordance with a second embodiment of the present invention.

[0051] Figure 21a to e are third, fourth, fifth, sixth and seventh views of the integral vacuum generator and cooling fan in accordance with a second embodiment of the present invention.

Details Description of the Embodiments

[0052] There will now be described by way of example a specific mode contemplated by the inventors. In the following description numerous specific details are set forth in order to provide a thorough understanding. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure

the description.

[0053] With reference to figures 1-3 there is shown a power tool 1000, more specifically a sliding mitre saw, although it will be apparent to one skilled in the art that any power tool which, in use, generates debris and dust will be suitable, such as grinders, circular saws, mitre saws, chop saws, cut-off saws, and table saws.

[0054] The mitre saw 1000 comprises a base 1001 which supports the mitre saw upon a surface and also supports a substrate to be cut by the saw.

[0055] From the base 1001 there is a neck 1002 which is pivotable about the base 1001 in order to support the cutting head to provide a straight or bevel cut.

The neck 1002 is temporarily fixable to the base 1001 by a fixative once a required bevel angle has been selected.

[0056] Connected to the neck 1002 is at least one sliding rail 1003, which slidably supports a cutting head 1004. The cutting head 1004 rotates with the neck 1002 and base 1001 in order to provide a mitre cut.

[0057] Typically, in order to afford stability to the cutting head 1004, two sliding rails 1003, 1005 are provided, one above the other (i.e. an upper rail 1003 and a lower rail 1005). However, it will be readily apparent that the teachings of the present invention are applicable to all forms of power tools which generate dust and thus not limited to a mitre saw having sliding rails.

[0058] The cutting head 1004 may be raised and lowered relative to the sliding rails 1003, 1005. In an upper raised position the cutting head 1004 is arranged to avoid making a cut in a substrate to be cut. In a lower position the cutting head 1004 is positioned to make a cut in a substrate supported by the base 1001. In the upper raised position, the cutting head is at an angle of approximately 35° to 55° relative to the sliding rails 1003, 1005. The sliding rails 1003 and 1005 are aligned in parallel with the base 1001. In the lowered position, the cutting head is substantially aligned with the sliding rails 1003, 1005 and thus is substantially in parallel with the base 1001.

[0059] The cutting head 1004 comprises an operating handle 1006 with saw operation means such as a trigger switch 1007, cutting blade 1008, and a blade guard 1009. The blade guard 1009 is arranged to obscure the cutting blade 1008 when the cutting head 1004 is in the upper position, and to reveal the cutting blade 1008 when the cutting head 1004 is in the lower positon.

[0060] The cutting head 1004 further comprises a housing 1010 which substantially envelopes and protects the internal components of the mitre saw 1000. The internal components are those necessary for the function and operation of the saw, such as the motor 2000, gearing, electrical cabling, safety mechanisms, and switching.

[0061] The housing 1010 may be at least partially cover the cutting blade 1008 of the saw 1000 as well as the blade guard 1009 for safety purposes. The housing 1010 may be constructed of any suitable material including plastics or metals. Preferably, the housing is constructed from die cast aluminium which can be easily machined into complex structures which include for example bore holes and complementary fitments.

[0062] The housing 1010 comprises integral ducting 1011 which is preferably formed by two half-channels which form an integral duct 1011 when the respective parts of the housing 1010 are combined. The ducting has two regions an inlet region 1011i and an exhaust region 1011e.

[0063] The integral ducting permits the flow of various fluids (typically, but not limited to gases, such as air) about the housing 1010 to provide various functions, such as cooling via a cooling fluid e.g. air. Air is drawn into the motor housing cooling airflow inlet 1015, which is part of a subassembly incorporated into the housing. Alternatively, the housing may comprise an integral inlet. Once air is drawn into the housing 1010, it is directed to the internal components that require cooling (such as the tool driving motor 2000), and then the cooling fluid is expelled though an exhaust.

[0064] Integral ducting 1011 may also be used to enable the flow of a debris collection fluid (such as air) from a scoop 1013 (i.e. the inlet) which is adjacent the saw 1000, to a debris collector (not shown) located at an exhaust 1012 on the housing 1010.

[0065] The scoop 1013 is arranged to catch any debris generated by the powered tool (in the case of a circular saw this may be from the inertia of the rotating blade imparting motion to the debris and flinging debris towards the scoop 1013). The scoop 1013 should be shaped to maximize the chance of capturing any debris generated by the power tool, such as a flared shape. The scoop 1013 may be made from a flexible material, such that it can be reversibly deformed to fit within a gap narrower than the width of the scoop 1013.

[0066] By integrating the ducting as part of the housing 1010 construction of the mitre saw 1000 is simplified as fewer parts are necessary. Furthermore, it is simpler to attach two or more housing sections together to form the integral ducting 1010 rather than attach and arrange integral separate tubing within housing sections and they try to assemble the complete structure.

[0067] It will be apparent that the housing 1010 may suitably be formed in a single section whereby the integral ducting 1011 is formed as a complete section in a single manufacturing step upon the formation of the housing 1010 e.g. by molding, injection molding, die cast molding, or 3D printing/sintering. Alternatively, the integral ducting 1011 could be formed of a plurality of parts fastened together.

[0068] The integral ducting 1011 should always be designed to provide a smooth and short path to minimize the risk to debris becoming trapped and building up within the power tool 1000.

[0069] Since the integral ducting 1011 is integral to the housing 1010 the integral ducting 1011 may perform additional functions such as providing internal structural rigidity to the housing 1010. This means that it is not necessary to use additional material to form the housing 1010 compared to if no integral ducting 1011 was provided. Furthermore, the use of integral ducting 1011 means that the footprint and dimensions of the power tool 1000 need not be increased relative to a power tool which does not comprise any ducting (integral or otherwise).

[0070] Located in the housing 1010 are the internal components necessary for the power tool 1000 to be operated. In the case of a mitre saw 1000 this includes a motor 2000. The tool-diving motor 2000 is arranged to power the circular saw blade 1008 fitted to the mitre saw 1000. The circular saw blade 1008 is therefore a powered tool. Other powered tools may include various types of saws, drills, sanders, chasers, grinders or other known items in the art. A powered tool is one which the user is assisted in operation of the tool by an additional means, such as an electric motor or pneumatic/hydraulic means.

[0071] In the present embodiment the motor 2000 is electric, deriving power from either a battery or mains electric power source. In the alternative a different power source could be used, such as an internal combustion engine or other normal methods of providing a motor 2000 provided it can be located internally in the housing.

[0072] Referring to figures 4 to 8, the tool-driving motor 2000 is connected to a drive shaft 2001 which transmits the output of the driving motor 2000 to principally the powered tool 1000. The drive shaft 2001 may be linked directly to the powered tool 1000 (i.e. direct drive) or via a set of gears.

[0073] A vacuum generator 2002, is also connected to the motor 2000. A vacuum generator will be understood to be a fan having angled blades which direct fluid flow towards the integral ducting of the housing to provide a fluid flow path from the powered tool 1000, a debris collection scoop. This is to provide an extraction route for the removal of debris generated by the powered tool 1000 via the housing 1010.

[0074] Preferably the vacuum generator 2002 is a cyclonic centrifugal fan comprising a pair of spaced apart discs with vanes sandwiched there-between. One of the discs 2003 is provided with an inlet aperture 2004 arranged towards a hub of the disc. The hub of this disc 2003 need not be connected to the drive shaft 2001, as the vanes 2005, connected to the second disc 2006 can provide the structural support to keep the first disc 2003 in the required place.

[0075] By sandwiching the vanes 2005 between two plates 2003, 2006 the flow of fluid through the centrifugal fan is contained minimizing the risk of debris within the fan being carried by a fluid and preventing contamination of other parts of the power tool 1000.

[0076] The centrifugal fan is connected directly to, and driven by, the drive shaft 2001 through the second disc 2006. Although it will be apparent to one skilled in the art that a set of gears could be used, or other means, and that the centrifugal fan may be placed in a remote position relative to the driving motor 2000 as opposed to the present embodiment where the centrifugal fan is adjacent the driving motor 2000.

[0077] It will be understood that the vacuum generator 2002 may take alternate forms for example or example there are many possible fan blade geometries e.g. forward or reverse curved, straight or twisted any of which may operate radially or axially.

[0078] Ideally, the centrifugal fan is designed so that it may provide the optimum fluid flow rate when in direct drive from the motor 2000 thereby negating the need for gearing, electronic or mechanical control to change the rotation speed of the centrifugal fan, although it will be apparent to one skilled in the art this may be necessary in some applications.

[0079] The inlet aperture 2004 of the centrifugal fan is arranged to interface with a portion of the integral ducting 1011 of the housing 1010 to provide a fluid flow path from the powered tool 1000, the scoop 1013, and into the inlet aperture 2004 of the centrifugal fan. This is to provide an extraction route for the removal of debris generated by the powered tool 1000 via the housing 1010.

[0080] The debris passes though the inlet aperture 2004 of the centrifugal fan whereupon it is urged by the rotation of the fan to the perimeter circumference 2007 of the discs 2003, 2006 and into further integral ducting 1011 of the housing 1010. The integral ducting 1011 comprises an inlet portion 1011i and an exhaust portion 1011e. The inlet portion of the integral ducting 1011i is adjacent to the scoop 1013 so that the debris collected by the scoop is gathered in a position where the suction airflow can pull the debris into the inlet portion of the integral ducting 1011i. This inlet part of the integral ducting is in the lower part of the assembly and the start of the debris' path through the ducting toward the fan and scroll and onward into the exhaust portion 1011e, finally ending in the debris collector. The inlet and exhaust portions are characterized by their relative positions before or after the fan assembly, which generates the airflow for both cooling and suction. The inlet portion 1011i is between the scoop and the fan while the exhaust portion 1011e is between the fan and the outlet port 1012, or otherwise out of the power tool, having passed though the relevant part of the enclosed fan, fan housing, scroll or volute 1014 with the rest of the airflow.

[0081] A portion of the integral ducting 1011 is arranged to encompass the circumference 2007 and space bounded by the two spaced apart discs 2003, 2006 is called the scroll 1014 and is arranged to collect and channel the debris exiting the centrifugal fan, and direct the debris into a debris collector (not shown) connected to the housing 1010. Preferably, the scroll 1014 is immediately adjacent to, and feeds into the collector via an outlet port 1012 located on the housing. This minimizes the distance for the debris to travel into the collector 1013 minimizing the risk of any debris becoming lodged within the housing 1010.

[0082] The driving motor 2000 is further connected to a cooling fan 2008. The cooling fan 2008 typically comprises a single disc 2009 having a plurality of vanes 2010 located upon a circular face of the disc 2009 such that as the disc 2009 rotates the vanes 2010 to urge fluid flow.

[0083] The cooling fan 2008 is preferably located adjacent the motor 2000 in order to draw a cooling fluid (such as air) across the motor 2000 from a cooling fluid inlet 1015 which is a subassembly incorporated into the housing 1010, although it will be apparent to one skilled in the art that the cooling fan 2008 may be located remotely from the driving motor 2000 and the cooling fluid channeled to the driving motor 2000 by integral ducting 1011 (the integral ducting 1011 carrying the unused cooling fluid being separate to the integral ducting 1011 carrying debris).

[0084] The cooling fan 2008 is connected to the tool-driving motor 2000 drive shaft 2001 and receives driving power from the motor 2000 along with the powered tool 1008 and the vacuum generator 2002. It will be apparent to one skilled in the art that the cooling fan 2008 may be in direct drive with the driving motor 2000 (i.e. the cooling fan 2008 rotates at the speed of rotation of the motor 2000), or via a set of gears of other means for altering the speed of rotation of the cooling fan 2008. It is preferable for the cooling fan 2008 to be direct drive in order to minimize the complexity of the power tool 1000.

[0085] Cooling fluid can be any required for cooling the motor 2000 such as air, water, or oil. In the present embodiment air is used as it is the common choice for electric motors used to drive power tools. The air is drawn in the cooling fluid inlet 1015 of the housing 1010, across the driving motor 2000 by the cooling fan 2008 where the air cools the tool-driving motor 2000 (and correspondingly becomes a "used" cooling fluid), and is then expelled via the exhaust portion 1011e of the integral ducting 1011 to an exhaust 1012 on the housing 1010.

[0086] The exhaust 1012 may be a common exhaust such as that also used by the vacuum generator 2002 to expel debris into a debris collector. If this is the case then the integral ducting 1011 of the housing 1010 merges the fluid flows from the vacuum generator 2002 and the cooling fan 2008 at a safe point. The safe point minimizes the risk of contamination of the sensitive parts of the power tool 1000 (such as the tool-driving motor 2000) from debris. Accordingly, the fluid flows are only combined once the cooling fluid is used (i.e. the cooling fluid has already been passed over the components to be cooled). In this instance the cooling fluids are preferably of the same phase (i.e. both in the same state as a liquid or a gas).

[0087] Before the cooling fluid and fluid carrying the debris are combined the fluids are directed and urged to flow in substantially opposing directions. For example, the cooling fluid is urged as it passes over the components to be cooled in a direction opposing the flow of the fluid carrying debris. Should any debris enter any region of the power tool 1000 where the cooling fluid is flowing, the cooling fluid will pick up that debris and urge the debris in the direction of the exhaust 1012, away from any sensitive componentry (such as the driving motor 2000).

[0088] The separation of the cooling fluid and the fluid carrying the debris is further assisted by the use of a labyrinth seal located in an aperture of the housing 1010 through which the drive shaft 2001 passes. The labyrinth seal may be integral to the housing reducing the number of parts required to construct the power tool 1000.

[0089] When the exhaust 1012 is a common exhaust, a membrane, barrier, baffle or similar may be located in at least part of the exhaust 1012 to ensure that the cooling fluid and the fluid carrying the debris are only combined at a safe distance from the internal components of the power tool 1000.

[0090] The cooling fan 2008 and vacuum generator 2002, when both directly driven by the motor 2000, or otherwise being both rotated in a common direction (e.g. both clockwise or both anti-clockwise) are able to urge fluid flow in substantially opposing directions by arranging the respective cooling fan vanes 2010 (or fins) and vacuum generator vanes 2005 (or fins) with substantially opposing curvature relative to one another (i.e. when both the cooling and centrifugal fans are fixed in place on the drive shaft 2001, a given vane 2010 on the cooling fan has an aerodynamic geometry complementary to a vane 2005 on the centrifugal fan) and directing the fluid flow inlets to each fan accordingly to achieve the required flow direction. For example, a given vane on the cooling fan may have concave curvature relative to a convex curve on the centrifugal fan.

[0091] Referring to figures 9 to 21, a second embodiment of the present invention 3000 is depicted in which the cooling fan 3001 is an integral part of the vacuum generator 3002. A groove is present between the 'cooling' and 'vacuum' components. The fan housing has a 'diaphragm' feature that fits this groove which serves as a physical barrier to prevent the incoming 'dirty' airflow sucked up from the cutting operations from mixing with the clean airflow coming from the cooling fan 3001. The cooling vanes 3003 of the cooling fan 3001 are located upon the external surface of a disc 3004 of the vacuum generator 3002.

[0092] Referring to figures 9 and 10, a front and rear perspective view of the second embodiment of the present invention respectively, the vacuum generator is a dust-collecting mechanism 3002 in the form of a cyclonic centrifugal fan connected to a driving motor comprising a rotor 3005 and stator 3006. The dust-collecting mechanism cyclonic centrifugal fan 3002 comprises a pair of circular spaced apart discs with dust collecting blades 3010 sandwiched there-between. The cyclonic, centrifugal or other fan mechanism 3002 is fixed to the motor stator 3006 by front and rear bearings. One of the discs 3007 is provided with an inlet aperture 3008 arranged substantially centrally of the disc. The hub of this disc 3007 is not directly connected to the drive shaft 3009, rather the vanes 3010 are fixedly connected to the disc 3004 which in turn is fixedly connected to the rotor 3005 of the driving motor.

[0093] The vanes 3010 are located between two plates 3004 and 3007 in communication with the flow of fluid through the centrifugal fan, minimizing the risk of debris within the fan being disseminates to other parts of the power tool 1000.

[0094] The cyclonic centrifugal fan 3002 is connected directly to, and driven by, the solid steel motor drive shaft 3009 through the second disc 3007. The motor drive shaft 3009 may have gear splines cut into it or may further comprise a pulley of gear wheel. Although it will be apparent to one skilled in the art that a set of gears could be used, or other means, and that the centrifugal fan may be placed in a remote position relative to the motor 2000 as opposed to the present embodiment where the centrifugal fan is adjacent the motor 2000.

[0095] The centrifugal fan 3002 designed so that it may provide the optimum fluid flow rate when in direct drive from the rotor 3005 thereby negating the need for gearing or electronic control to change the rotation speed of the centrifugal fan, although it will be apparent to one skilled in the art this may be necessary in some applications.

[0096] The inlet aperture 3008 of the centrifugal fan is arranged to cooperate with a portion of the electric motor (3005 & 3006) to provide a fluid flow path from the powered tool (fig 1:1000, the scoop 1013), and the inlet aperture 3008 of the centrifugal fan to provide an extraction route for the removal of debris generated by the powered tool.

[0097] The cooling fan 3001, an integral part of the vacuum generator 3002 comprising a single disc 3011 and having a plurality of cooling vanes 3003 is located upon the circular face of the disc 3011 such that as the disc 3011 rotates the vanes 3003 to urge fluid flow and cool the device.

[0098] The cooling fan 3001 is located adjacent the rotor 3005 in order to draw air across the motor to cool the device. The cooling fan 3001 is connected to the motor drive shaft 3009 and receives driving power from the motor 3005 along with the powered tool (fig 1:1000) and the vacuum generator 3002.

[0099] The cooling fan 3001 and vacuum generator 3002, when both directly driven by the rotor 3005, or otherwise being both rotated in a common direction (e.g. both clockwise or both anticlockwise) are able to urge fluid flow in substantially opposing directions by arranging the respective cooling fan vanes 3003 (or fins) and vacuum generator vanes or fins 3010 with substantially opposing curvature relative to one another (i.e. when both the cooling and centrifugal fans are fixed in place on the drive shaft 3009, a given vane 3003 on the cooling fan has an aerodynamic geometry complementary to a vane 2005 on the centrifugal fan) and directing the fluid flow inlets to each fan accordingly to achieve the required flow direction.

[0100] Referring to figure 12 herein, between the circular face of the disc 3011 of the cooling fan and the nearest adjacent disc 3004 of the vacuum generator there is a circular cylindrical annular gap surrounding a circular cylindrical surface which extends between the vanes of the cooling fan and the plate of the vacuum generator. This is wide enough to include wall portions from an external housing casing which fits around the cooling fan and vacuum generator assembly and provides a separation wall between a cooling fluid flow produced by operation of the cooling fan and a dust extraction airflow produced by operation of the vacuum generator.

[0101] Referring to figures 11 and 13, front and rear side views respectively and figure 12 a right side view of the second embodiment of the present invention, the vacuum generating dust-collection mechanism 3002 is connected to motor rotor 3005 in the form of a cyclonic centrifugal fan which is incorporated into the electric motor as assembled with the motor stator 3006. The dust-collecting mechanism cyclonic centrifugal fan 3002 comprising a pair of circular spaced apart discs (3004, 3007) arranged coaxially around the drive shaft 3009 of the motor rotor 3005. The pair of circular spaced apart discs (3004, 3007) have vanes 3010 mounted around a hub which curve away from the axis of rotation of the rotor shaft 3009. The vanes 3010 will be understood to be any projection, fin or blade which may be driven by the motor rotor 3005. The discs (3004, 3007) and vanes 3010 form the centrifugal fan wheel which has a drum shape. The plurality of vanes 3010 mounted around a hub may be considered dust collecting blades. Thus, the dust collecting blades 3010 are sandwiched between first and second spaced apart discs (3004, 3007). The cyclonic centrifugal fan 3002 is assembled with the motor stator 3006 by rear bearings 3012. The bearings at the front and rear of the rotor support and align the rotor to enable it to spin smoothly. One of the discs 3007 is provided with an inlet aperture 3008 arranged substantially centrally of the disc. The hub of this disc 3007 is not directly connected to the drive shaft 3009, rather the vanes 3010 are fixedly connected to the disc 3004 which in turn is fixedly connected to the driveshaft rotor of the driving motor 3005. The vanes 3010 are located between two plates 3004 and 3007 in communication with the flow of fluid through the centrifugal fan, minimizing the risk of debris within the fan being disseminated to other parts of the power tool 1000. As the hub of disc 3004 turns on the driveshaft mounted in bearings in the fan housing, air enters a first side of the fan wheel flows over the blades and is displaced by vanes 3010 which radiate or curve away from the axis of rotation of the rotor shaft 3009, the air is accelerated by centrifugal force and the air exits the fan wheel at approximately 90° to the air inlet.

[0102] Referring to figures 13 and 14, front and rear perspective views respectively of the second embodiment of the present invention. The motor assembly comprises a rotor 3005 and stator 3006. Figures 13 and 14 illustrate the motor rotor assembly 3005 absent of the motor stator 3006, the vacuum generating dust-collection mechanism 3002 is connected to driving motor 3005 in the form of a cyclonic centrifugal fan 3001.

[0103] Referring to figures 16 and 18, front and rear side views respectively and figure 12 a right side view of the second embodiment of the present invention absent of the motor stator 3006, the vacuum generating dust-collection mechanism 3002 is connected to the motor rotor 3005 and also connected to a cooling fan 3001.

[0104] Referring to figures 19 and 20, front and rear perspective views respectively of the integral structure of the cooling fan 3001 and vacuum generator 3002 in accordance with the second embodiment of the present invention. The cooling vanes 3003 of the cooling fan 3001 are located upon the external surface of disc 3011. The fan 3001 comprises a substantially annular disc -shaped member having extending radially therefrom a plurality of individual cooling vanes 3003. Each cooling vane 3003 extends radially from a main central axis of said cooling fan, said plurality of cooling vanes being equidistantly spaced apart from its immediately neighboring cooling vanes 3003 so that the cooling vanes 3003 are arranged around the circumference of the disc-shaped member 3011 by equal spacing or gaps between adjacent cooling vanes, and are arranged on one side of disc -shaped member. Each cooling vane 3003 has a leading main surface 30031 and a trailing main surface 3003t, the leading and trailing surfaces of a cooling vane 3003 being on opposite sides of a main body of said cooling vane. In use, the leading surface 30031 pushes air in a main cooling air flow direction, by virtue of a relatively increased air pressure leading surface, whereas a relatively reduced air pressure exists at the trailing surface 3003t with the resulting pressure difference causing a cooling air flow in a direction substantially coincident with the main rotational axis of said disc-shaped member.

[0105] The vacuum generator comprises first and second disc shaped members arranged spaced apart from each other and parallel to each other. Between said first and second discs are provided a plurality of curved or arcuate vanes 3010 arranged each extending from an inner (smaller) radius to an outer (larger) radius relative to the main central axis. Each blade has a leading edge and a trailing edge, and each blade, along with its immediately neighboring adjacent blade defines there between an air passage between said blade and said immediately adjacent blade such that when said vacuum generator rotates, air passes in a direction between the outer (larger) radius portion and the inner (smaller) radius vacuum generator and in a direction which lies across a main rotational axis of said vacuum generator. Each air passage extends from an inner radial end to an outer radial end relative to the main central axis of rotation, with air flowing along each air passage as the vacuum generator rotates.

[0106] The cooling vanes 3003 (or fins) and vacuum generator vanes 3010 have substantially opposing geometry relative to one another (i.e. when both the cooling and centrifugal fans are fixed in place on the drive shaft 3009, a given cooling vane 3003 on the cooling fan has a complementary profile relative to the form of a vane 3010 on the centrifugal fan) and directing the fluid flow inlets to each fan accordingly to achieve the required flow direction.

[0107] Referring to figures 21a to 21e, underside, front perspective, side view, rear perspective and upperside views respectively of the integral structure of the cooling fan 3001 and vacuum generator 3002 in accordance with the second embodiment of the present invention. The cooling vanes 3003 of the cooling fan 3001 are located upon the external surface of disc 3011. The cooling vanes 3003 and vacuum generator vanes 3010 are orientated at an opposing geometry relative ^ to one another. In the illustrated example, when both the cooling and centrifugal fans are fixed in place on the drive shaft 3009, a given cooling vane 3003 on the cooling fan has a concave curvature relative to a convex vane 3010 on the centrifugal fan.

[0108] The powered cutting head of the saw is assembled using a specific method of assembly which enables the fan unit to be fitted to the cutting head of the power tool as a single piece, without the need for additional hardware or access windows. Referring to figure 22 there is shown an exploded view of a mitre saw power tool assembly in accordance with the present embodiment for the purpose of illustrating the method of assembling the same. The mitre saw comprising a cutting head 1004 having a first side 4000, a powered circuit board housing 4001; a fan housing comprising first 4002 and second 4003 parts optionally located at the front and rear of the fan; a motor rotor 3005; a motor stator 3006 housed in a motor housing 4004. The first 4002 and second 4003 parts comprising the fan housing receive the integral ducting 1011 and the fan unit 4005 which itself comprises the vacuum generator 3002 and cooling fan 3001.

[0109] Figures 22 to 28 illustrate schematically the method of assembling the power tool comprises the steps of: - installing the integral ducting 1011 on to a first side 4000 of the cutting head 1004 of the power tool; - locating the motor stator 3006 within the motor housing 4004; -mounting the second part 4003 of the fan housing and the fan unit 4005 on the motor rotor 3005 and positioning the combined rear housing 4003, fan unit 4005 and motor rotor 3005 on to the cutting head 1004 of the powered tool; the rear housing 4003 fits over the top of integral ducting 4000 to lock the integral ducting 4000 in position and aligning the outlet of the ducting to supply debris filled airflow into the fan housing; the first part 4002 of the fan housing is then added to the cutting head assembly 1004 to secure the fan unit's 4005 position; the final position of the two-part fan housing (4002; 4003) is perpendicular to a first side 4000 of the cutting head 1004; the 'diaphragm' or 'barrier' feature of the first part 4002 of the fan housing engages with a groove between the vacuum generator 3002 and cooling fan 3001 components of the fan unit 4005, to seal the fans (3002;3001) by the integrated labyrinth seal feature integral to the parts form; when the motor stator 3006 and fan unit 4005 are in location and the fan housing and ducting components (4002, 4003, 1011), the motor housing 4004 (which contains the pre-installed motor stator 3005) is installed; installation of the dust collection fan mechanism is then complete; finally a powered circuit board housing 4001 is fitted.

[0110] The two-part fan housing advantageously permits a method of assembly in which the complete fan unit (comprising the motor, vacuum generator and cooling fan) can be mounted to the cutting head of the power tool as one unit, leading to improved manufacturing, manufacturability and assembly which increases the reliability of the finished power tool. The fan housing and ducting components 4002, 4003 each comprise a respective wall portion having semicircular apertures, so that the two fan housing and ducting components when mated together form a circular aperture. The circular aperture fits into the gap between the cooling fan and the vacuum generator, thereby providing a separation barrier between the cooling air flow used to cool the motor and the dust extraction airflow which extracts dust from the power tool and the work area around the power tool.

[0111] Figure 27 shows the fully assembled cutting head 1004 in a first perspective view, comprising the assembled fan housing 4002;4003 and motor housing 4004; figure 28 shows the fully assembled cutting head 1004 comprising the assembled fan housing 4002;4003 and motor housing 4004 in a second perspective view.

[0112] It will be apparent to a person skilled in the art that alternative embodiments of the present invention may be feasible. Any form of complementary geometry may be used for the vanes of the cooling fan and the suction fan each having complementary raked angles. It will be further understood that that teachings of this document are applicable to other forms of cutting or grinding power tools which generate debris for example chop saws; circular saws; and like tools.

[0113] Where the integral cooling fan 3001 and vacuum generator 3002 of 15 the second embodiment are located remotely from the motor (3005 & 3006) they may be provided as a detachable-module as an accessory to a power tool.

Advantageous features [0114] The specific embodiments described herein include the following features which alone or in combination contribute to the advantages provided by the specific embodiments.

[0115] The power tool has a combined dust collection! cooling fan integrated with the saw's electric motor.

[0116] Blade Guard Linkage: A clever blade guard operating linkage that operates on the upper half of the saw to clear space behind the arbour and permit the cutting of tall, thin workpieces such as wooden boards, using the portion of the blade behind the arbour. An example would be skirting boards oriented vertically, as viewed when installed. Usually in prior art mitre saws, the arbour flange and guard linkage components set an absolute limit on the size of wood which can be cut -and the saw runs out of blade when that flank is reached. This novel blade guard linkage disclosed herein runs away from that area so that the space can be used for cutting [0117] Front operated angle detent / bevel control mechanism: This lets the user set a bevel angle with controls mounted on the front of the saw -the prior art way involved reaching around behind the saw.

[0118] The embodiments may comprise a 3-stage gearbox mechanism to increase the saw's cutting capacity. This gearbox shifts the axis and location of the motor up and forward to work in conjunction with the top-routed blade guard linkage to enable the ability to cut tall, thin pieces of wood behind the arbour flange.

[0119] The embodiments may comprise a space-saving slide rail system for a bench-top mitre saw in which the saw's cutting head slides back and forth on a pair of vertically stacked stationary sliding rails. With this kind of sliding rail system, the saw's footprint stays constant in use. Traditional prior art sliding mitre saws have their cutting head fixed on the end of some sliding rails that move back and forth and poke out of the saw to the rear as their aft-most extent of travel. This constantly protruding rail movement prevents such a saw from fitting nicely against a wall on a workbench or countertop in use.

[0120] The fan housing being split front & back allows the parts to be tooled advantageously to avoid undercuts [0121] Having a two-part shell construction for the vacuum generator and cooling fan housing allows the fan to be easily installed in one piece without added hardware or splitting the fan into two parts. The challenge is that there is a groove in the fan body to separate the "cooling" and "vacuum" halves of the fan. This needs a "diaphragm" to fit in the groove and prevent the "dirty" air sucked up by the vacuum from mixing with the clean "cooling" air flow pulled in by the cooling side of the fan.

[0122] Having split front & rear fan housings eliminate the need for an extra smaller "diaphragm" part that would have to fit the groove or annular gap between the fan's "cooling" and "vacuum" halves [0123] This kind of construction is much easier to assemble and uses fewer components than the alternatives.

[0124] The assembled "stack" of components on the rotatable shaft features some undercut forms that can't just be "inserted" axially into the enclosure like most electric motors. These features such as: cylindrical fan forms, bumps, and grooves need to be tightly enclosed to work effectively and the front/back split housing is a simple way to enable this function, maintain close tolerances and fits, prevent air leaks and retain a production-ready assembly method.

[0125] Other methods involve added steps or threading parts onto a shaft, sometimes these need added fasteners and steps to secure components onto the shaft such as: collars, grub screws, and shims. All these fastening components require access for the tool to tighten or loosen them, which meant in the past we had to leave access holes for a tool, which really is unsatisfactory. Some reasons this is unsatisfactory are: aesthetics, safety, manufacturability, complexity of assembly, excessive piece count in the assembly, balance, noise, imperfect airflow, and the safety risks of having high-speed spinning shafts near an open hole with exposed fasteners and components.

[0126] The completed subassembly must be dynamically balanced to work properly without wobbling, making noise, wearing out prematurely or flying apart. The idea of assembling components separately is contrary to every method of establishing and maintaining a balanced state with these components.

Claims

Claims 1. A power tool comprising: a housing; a motor located within the housing; a vacuum generator; a cooling fan; and a drive shaft for a powered tool; the motor providing driving power to said drive shaft, said vacuum generator, and said cooling fan; wherein the vacuum generator has a first fluid flow in a first direction; and the cooling fan has a second fluid flow in a second direction and said first and second directions are substantially opposing directions relative to one another.
2. A power tool as claimed in claim 1 wherein the vacuum generator and cooling fan comprise a single fan unit.
3. A power tool as claimed in any preceding claim wherein the cooling fan is arranged to cool said motor located within said housing.
4. A power tool as claimed in any preceding claim wherein the housing comprises a fan housing having first and second parts.
5. A power tool as claimed in any preceding claim wherein the housing comprises integral ducting providing a debris collection channel.
6. A power tool according to claim 5 wherein the debris collection channel is arranged to collect debris generated by the powered tool and channel the debris via said vacuum generator to a debris collector.
7. A power tool as claimed in any of claims 5 or 6 wherein the integral ducting comprises an inlet, the inlet being adjacent the powered tool.
8. A power tool as claimed in any previous claim wherein the housing further comprises integral cooling ducting arranged to channel a cooling fluid over the motor.
9. A power tool as claimed in any preceding claim wherein said first and second fluid flows having substantially opposing directions relative to one another leave the housing at a common exhaust.
10. A power tool as claimed in any preceding claim wherein said first and second fluid flows having substantially opposing directions relative to one another flow in substantially partitioned ducting wherein a first fluid is a clean fluid relative to an at least second dirty fluid.
11. A method of assembling a vacuum generator within a power tool, the power tool comprising: a housing a motor located within the housing; a vacuum generator; a cooling fan; and a drive shaft for a powered tool; the motor having a stator and a rotor which provides driving power to said drive shaft, said vacuum generator, and said cooling fan; wherein the vacuum generator has a first fluid flow in a first direction, and the cooling fan has a second fluid flow in a second direction and said first and second directions are substantially opposing directions relative to one another; wherein the housing comprises a motor housing and the motor; and a fan housing having first and second parts; and the motor comprises a motor stator and a motor rotor; the power further comprising a cutting head; the method comprising the steps of: a. locating said motor stator within said motor housing; b. mounting said first part of said fan housing, said vacuum generator and said cooling fan on said motor rotor and positioning the same on said cutting head; c. mounting said second part of said fan housing on said motor rotor; d. mounting said motor housing containing said motor stator onto said cutting head of said power tool;
12. A method of assembling a vacuum generator within a power tool, a ccording to claim 11 further comprising the steps of: e installing a dust collection fan mechanism.f. fitting a powered circuit board housing.
13. A fluid flow generator for a power tool comprising: a disc having; at least one vacuum generating vane on a first face; and at least one cooling fluid flow generating vane on a second face; wherein; the at least one vacuum generating vane arranged on the first disc face constitutes a vacuum generator; and said at least one cooling fluid flow generating vane arranged on the second disc face constitutes a cooling fan.
14. A fluid flow generator as claimed in claim 13 wherein the at least one vacuum generating vane is further connected to a face of a second disc such that the first disc and second disc are spaced apart by the at least one vacuum generating vane.
15. A fluid flow generator as claimed in claim 14 wherein the second disc comprises an inlet arranged towards a disc hub of the second disc.
16. A fluid flow generator as claimed in either claim 14 or 15 wherein an outlet is provided towards a disc rim of the second disc.
17. A fluid flow generator as claimed in any of claims 13 to 16 wherein the at least one vacuum generating vane and the at least one cooling fluid vane are arranged to urge fluid flow in substantially opposing directions relative from one fluid to another.
18. A power tool comprising the fluid flow generator as claimed in any of claims 13 to 17.