Motor, fan and cyclonic separation apparatus arrangement

A motor, fan and cyclonic separation apparatus arrangement for a vacuum cleaner comprising: a motor coupled to a fan for generating air flow; and a cyclonic separation apparatus located in a path of the air flow generated by the fan. The cyclonic separation apparatus comprises: a plurality of cyclones each with an air inlet port and an air outlet port; and a cooling air flow path. The motor comprises a permanent magnet brushless motor, a switched reluctance motor or a flux switching motor. The fan has an outer diameter the same or less than the diameter of the motor. The plurality of cyclones, the motor and the fan are arranged in a circular array about a central axis of the cyclonic separation apparatus. The arrangement comprises a baffle for directing air flow from the fan out of the circular array. The motor is located in the cooling air flow path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to EP Patent Application No. EP 11 184 789.3 filed Oct. 12, 2011, the contents thereof to be incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a motor, fan and cyclonic separation apparatus arrangement. In particular, but not exclusively, the present invention relates to a motor, fan and cyclonic separation apparatus arrangement for use in vacuum cleaners.

BACKGROUND OF THE INVENTION

Vacuum cleaners are well known for collecting dust and dirt, although wet-and-dry variants which can also collect liquids are known as well. Typically, vacuum cleaners are intended for use in a domestic environment, although they also find uses in other environments, such as worksites or in the garden. Generally, they are electrically powered and therefore comprise an electric motor and a fan connected to an output shaft of the motor, an inlet for dirty air, an outlet for clean air and a collection chamber for dust, dirt and possibly also liquids. Electrical power for the motor may be provided by a source of mains electricity, in which case the vacuum cleaner will further comprise an electrical power cable, by a removable and replaceable battery pack, or by one or more in-built rechargeable cells, in which case the vacuum cleaner will further comprise some means, such as a jack plug or electrical contacts, for connecting the vacuum cleaner to a recharging unit. When the vacuum cleaner is provided with electrical power from one of these sources, the electric motor drives the fan to draw dirty air along an air flow pathway in through the dirty air inlet, via the collection chamber to the clean air outlet. The fan is often a centrifugal fan, although it can be an impeller or a propeller.

Interposed at some point along the air flow pathway, there is also provided some means for separating out dust and dirt (and possibly also liquids) entrained with the dirty air and depositing these in the collection chamber. This dirt separation means may comprise a bag filter, one or more filters and/or a cyclonic separation apparatus.

In the event that the dirt separation means comprises a bag filter, dirty air, which has entered the vacuum cleaner via the dirty air inlet, passes through the bag filter. This filters out, and collects within the bag filter, dust and dirt entrained with the dirty air. The filtered material remains in the bag filter which lines the collection chamber. The clean air then passes to the other side of bag filter and through a grille in the collection chamber under the influence of the fan. The fan draws air in and expels it out, from where the air then passes to the clean air outlet of the vacuum cleaner.

There is always a small risk of dust and dirt passing through the bag filter and it is undesirable that it be allowed to pass through the fan and cause damage. To reduce this potential problem, there is often a fine filter located across the grille of the collection chamber to remove any fine dust and dirt particles remaining in the air flow after passage through the bag filter. This is commonly known as a pre-fan filter.

Occasionally, and in addition to any pre-fan filter, there is a high efficiency filter located downstream of the fan before the air flow leaves the vacuum cleaner. This is to remove any remaining extremely fine particulate matter which will not harm the fan or motor, but which may be harmful to the household environment. The term “filtering efficiency” is intended to relate to the relative size of particulate matter removed by a filter. For example, a high efficiency filter is able to remove smaller particulate matter from air flow than a low efficiency filter. A HEPA filter is a high efficiency filter which should be able to remove extremely fine particulate matter having a diameter of 0.3 micrometers (μm) and lower.

The purpose of the bag filter is to filter dust and dirt entrained in dirty air flow and to collect the filtered material within the bag filter. This progressively clogs the bag filter. The volumetric flow rate of air through the vacuum cleaner is progressively reduced and its ability to pick up dust and dirt diminishes correspondingly. Hence, the bag filter needs replacement before it becomes too full and before vacuum cleaner performance becomes unacceptable. The volume of the collection chamber must be sufficiently large to merit the cost of regular bag filter replacement.

An upright vacuum cleaner commonly has an upright main body with a dirt separating means, a motor and fan unit, a handle at the top and a pair of support wheels at the bottom. A cleaner head with a dirty air inlet facing the floor is pivotally mounted to the main body. A cylinder vacuum cleaner commonly has a cylindrical main body with a separating dirt means, a motor and fan unit and maneuverable support wheels underneath. A flexible hose with a cleaner head communicates with the main body. Bag filters are commonly used in upright and cylinder vacuum cleaners as separation means because their main body has sufficient internal space for the large collection chamber required to accommodate the bag filter.

In the event that the dirt separation means comprises a filter, dirty air, which has entered the vacuum cleaner via the dirty air inlet, passes through the filter. This filters out dust and dirt entrained with the dirty air and the filtered material remains in the collection chamber on the upstream side of the filter. Sometimes the filter is supplemented by a sponge to absorb any liquids entrained in the dirty air flow. The clean air then passes to the other side of filter under the influence of the fan, and from the fan the air then passes to the clean air outlet of the vacuum cleaner.

Filtered material accumulates around, and progressively clogs, the filter. The volumetric flow rate of air through the vacuum cleaner is progressively reduced and its ability to pick up dust and dirt diminishes correspondingly. Hence, the collection chamber needs regular emptying and the filter needs frequent cleaning to mitigate against this effect. Sometimes, the vacuum cleaner has a filter cleaning mechanism. Alternatively, the filter needs to be removable for cleaning with a brush, or in a dish washer, for example.

Hand-holdable vacuum cleaners, as their name would suggest, are compact and lightweight and are intended to perform light, or quick, cleaning duties around a household. Typically, hand-holdable vacuum cleaners are battery-powered to be easily portable.

An example of a hand-holdable vacuum cleaner having the conventional motor, fan and filter arrangement is described in European patent publication no. EP 1 752 076 A, also in the name of the present applicant. This vacuum cleaner has dirty air inlet at one end of a dirty air duct leading to a collection chamber with a filter. The collection chamber is generally cylindrical and is arranged transverse the body of the vacuum cleaner. The dirty air duct is rotatable, with the collection chamber, in relation to the body. The dirty air duct may be adjusted to access awkward spaces while the vacuum cleaner is held comfortably by a user.

In the event that the dirt separation means comprises cyclonic separation apparatus, dirty air, which has entered the vacuum cleaner via the dirty air inlet, passes through the cyclonic separation apparatus having one or more cyclones. A cyclone is a hollow cylindrical chamber, conical chamber, frustro-conical chamber or combination of two or more such types of chamber. The cyclone may have a vortex finder part way, or all way, along its internal length. The vortex finder is commonly a hollow cylinder and it has a smaller external diameter than the internal diameter of the cyclone.

Dirty air enters via a tangentially arranged air inlet port and swirls around the cyclone in an outer vortex. Centrifugal forces move the dust and dirt outwards to strike the side of the cyclone unit and separate it from the air flow. The dust and dirt is deposited at the bottom of the cyclone and into a collection chamber below. An inner vortex of cleaned air then rises back up the cyclone. The role of a vortex finder is to gather and direct the cleaned air through an air outlet port at the top of the cyclone. As an alternative to a vortex finder, the cyclone may have an inner cylindrical air permeable wall providing the cleaned air with a path from the cyclone. From the cyclone the cleaned air passes, under the influence of the fan, to the clean air outlet of the vacuum cleaner.

As with a bag filter, a vacuum cleaner with a cyclonic separation apparatus may have a pre-fan filter to protect the fan and motor, especially if the air flow is used to cool the motor. Nevertheless, volumetric flow rate of air through the vacuum cleaner remains virtually constant as separated material accumulates in the collection chamber. Thus, an attraction of cyclonic separation apparatus in a vacuum cleaner is a consistent ability to pick up dust and dirt. Another attraction is that the cost of regular bag filter replacement is avoided.

An example of an upright vacuum cleaner having a motor, fan and cyclonic separation apparatus is described in European patent publication no. EP 0 042 723 A. This cyclonic separation apparatus is divided into a first cyclonic separating unit with a cyclone formed by an annular chamber and a second cyclonic separating unit with a generally frustro-conical cyclone. The first cyclonic separating unit is ducted in series with the second cyclonic separating unit. Air flows sequentially through the first, and then the second, cyclonic separating units. The frustro-conical cyclone has a smaller diameter than the annular chamber within which the frustro-conical cyclone is partially nested. Separated material from both cyclonic separating units collects in the cylindrical collection chamber formed at the bottom of the annular chamber.

The term “separation efficiency” is used in the same way as filtering efficiency and it relates to the relative ability of a cyclonic separation apparatus to remove small particulate matter. For example, a high efficiency cyclonic unit can remove smaller particulate matter from air flow than a low efficiency cyclonic separating unit. Factors that influence separation efficiency can include the size and inclination of the dirty air inlet of a cyclone, size of the clean air outlet of a cyclone, the angle of taper of any frustro-conical portion of a cyclone, and the diameter and the length of a cyclone. Small diameter cyclones commonly have a higher separation efficiency than large diameter cyclones, although other factors listed above can have an equally important influence.

The first cyclonic separating unit of EP 0 042 723 A has a lower separating efficiency than the second cyclonic separating unit. The first cyclonic separating unit separates larger dust and dirt from the air flow. This leaves the second cyclonic separating unit to function in its optimum conditions with comparatively clean air flow and separate out smaller dust and dirt.

A hand-holdable vacuum cleaner having a motor, fan and cyclonic separation apparatus is described in United Kingdom patent publication no. GB 2 440 110 A. This cyclonic separation apparatus is smaller than that of EP 0 042 723 A in order to be used in a hand-holdable vacuum. It is divided into a first cyclonic separating unit and a second cyclonic separating unit located downstream of the first cyclonic separating unit. The separating efficiency of the first cyclonic separating unit is lower than that of the second cyclonic separating unit.

The second cyclonic separating unit of GB 2 440 110 A comprises six cyclones arranged in a circular array protruding into an annular chamber. The space within this circular array of cyclones is used to duct air flow from the annular chamber to the air inlet ports of the cyclones.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a motor, fan and cyclonic separation apparatus arrangement which makes more efficient use of the space it occupies. This is particularly desirable in a vacuum cleaner, where the efficient use of space is of great importance and any wasted space will necessarily add to the overall size and weight of the vacuum cleaner, without giving any counteracting benefit. It is also an object of the present invention to provide a motor, fan and cyclonic separation apparatus arrangement particularly suitable for use in a compact or hand-holdable vacuum cleaner. A further object of the invention is to provide a vacuum cleaner comprising such a motor, fan and cyclonic separation apparatus arrangement.

Accordingly, in a first aspect, the present invention provides a motor, fan and cyclonic separation apparatus arrangement for a vacuum cleaner, the arrangement comprising: a motor coupled to a fan for generating air flow; and a cyclonic separation apparatus located in a path of the air flow generated by the fan, wherein the cyclonic separation apparatus comprises: a plurality of cyclones each with an air inlet port and an air outlet port; and a cooling air flow path, wherein the motor comprises a permanent magnet brushless motor, a switched reluctance motor or a flux switching motor, wherein the fan is coaxial with the motor and the fan has an outer diameter substantially the same as or less than the outer diameter of the motor, wherein the plurality of cyclones, the motor and the fan are arranged in a generally circular array about a central axis of the cyclonic separation apparatus, wherein the arrangement further comprises a baffle for directing air flow from the fan out of the circular array and wherein the motor is located in the cooling air flow path.

The present invention makes improved use of the space occupied by the motor and fan by clustering them amongst a circular array of cyclones. This is possible because the outer profile of the motor and fan is generally cylindrical, like the cyclones. The motor and fan may be located on the edge of the circular array, in the middle or somewhere in between. The smaller diameter fan takes less space and, as a result, enables a more compact cyclonic separation apparatus than has hitherto been possible.

Preferably, the motor and the fan are nested within the plurality of cyclones. This surrounds the motor and fan with cyclones thereby reducing the air flow path between individual cyclones and the fan.

Preferably, the central axis of the cyclonic separation apparatus passes through the motor and the fan. The motor and fan are located near, or at, the middle of the circular array of cyclones so that the motor and fan occupy space that may otherwise be unused.

Preferably, the circular array of cyclones is axially symmetric and wherein the motor and the fan are concentric with the central axis. This provides a more compact cyclonic separation apparatus as the components are arranged evenly about the central axis.

Preferably, the axes of the plurality of cyclones are substantially parallel to the central axis of the cyclonic separation apparatus. This provides an array of cyclones which may be more easily arranged within a cylindrical dirt container, like, for example, the cyclones of the first and second embodiments of a cyclonic separation apparatus described below.

Preferably, the plurality of cyclones is at least eight cyclones arranged in a generally circular array having an inner annulus and an outer annulus and wherein the inner annulus diameter is at least30percent of the outer annulus diameter. This may provide space for a motor with sufficient power to drive the fan and provide sufficient air flow through the cyclonic separating apparatus.

Preferably, each cyclone comprises: a cyclone body with a hollow generally frustro-conical portion and a longitudinal axis; a discharge nozzle arranged at a longitudinal end of the frustro-conical portion; the air inlet port arranged tangentially through a side of the cyclone body; and the air outlet port through an opposite end of the cyclone body to the discharge nozzle. The vortex of air flowing towards the discharge nozzle of each cyclone accelerates as the cyclone body's diameter decreases to separate ever smaller dirt particles and to increase separation efficiency.

Preferably, the axes of the plurality of cyclones are outwardly inclined with respect to the central axis of the cyclonic separation apparatus to reduce space between the motor and the generally frustro-conical portion of each respective cyclone. The inclination of the cyclones provides a gap between the cylindrical portions of the cyclones which may be used by the baffle to expel air from the fan, as may be the case with a motor and fan nested amongst the cyclones of the hand-holdable vacuum cleaner disclosed by GB 2 440 110 A.

Preferably, the cyclonic separation apparatus comprises: a first cyclonic separating unit comprising a hollow substantially cylindrical dirt container concentric with the central axis of the cyclonic separation apparatus and an air inlet port arranged tangentially through a side of the dirt container; and a second cyclonic separating unit comprising the plurality of cyclones, wherein the second cyclonic separating unit receives air flow downstream from the first cyclonic separating unit. A dual cyclonic separation apparatus improves cleaning of dirty air by sharing separation of different particulate matter sizes between cyclonic separating units of varying separation efficiencies.

Preferably, the motor, the fan and the second cyclonic separating unit are located within the dirt container. This provides a more compact arrangement with regard to its axial dimension.

Preferably, an outer diameter of the motor is at least 15 percent of an outer diameter of the dirt container. This may provide a suitably sized dirt container to separate and collect larger dirt particles and provide suitable space for the circular array of cyclones, motor and fan.

Preferably, the second cyclonic separating unit has a higher separation efficiency than the first cyclonic separating unit. Large particulate matter is separated in the dirt container initially, leaving the high efficiency cyclones to separate the more difficult small particulate matter.

Preferably, the cyclonic separation apparatus comprises an intermediate wall arranged within the dirt container, wherein the intermediate wall surrounds the air inlet ports of the cyclones, wherein the intermediate wall defines a chamber with an air permeable wall arranged as an air outlet from the first cyclonic separating unit and wherein the second cyclonic separating unit receives air flow downstream from the first cyclonic separating unit via the chamber. The intermediate wall shields the air inlet ports from the dirty air flow vortex within the cylindrical dirt container. The air permeable wall provides an extra dirt filtration stage and deposits filtered dirt in the dirt container. Both these features help the cyclonic separation process.

Preferably, the fan is an impeller. This provides a compact design of fan capable of delivering suitable volumetric airflow at high rotational speeds.

In a second aspect, the present invention provides a vacuum cleaner comprising the motor, fan and the cyclonic separation apparatus arrangement according to the first aspect. The vacuum cleaner may be a more compact design because it benefits from the compact design of the motor, fan and cyclonic separation apparatus arrangement of the first aspect and it need not accommodate the motor or the fan within its body housing.

Preferably, the cyclonic separation apparatus comprises at least one protruding lip arranged to impede movement of separated material from said longitudinal end of the dirt container. This helps to avoid re-entrainment of separated dirt into the air flow destined for the cyclones. Preferably, the dirt container comprises a generally cylindrical exterior wall and a generally circular end wall at said longitudinal end of the exterior wall, wherein the air inlet port is arranged tangentially through the exterior wall and wherein the end wall is detachably connected to the exterior wall. The detachable end wall facilitates emptying of dirt in the dirt container. Preferably, the end wall is hingedly connected to the exterior wall so that the end wall is not mislaid after opening. Preferably, the plane of the discharge nozzle is inclined with respect to the longitudinal axis of the cyclone body. This helps to avoid separated material from re-entering the discharge nozzle. Preferably, the longitudinal axis of each cyclone is in line with the, central axis of the cyclonic separation apparatus. Preferably, the longitudinal axis of each cyclone is parallel with the central axis of the cyclonic separation apparatus. Preferably, the fan is a centrifugal fan having a tangential output. Preferably, the plurality of cyclones is no more than sixteen cyclones. More preferably the plurality of cyclones is no more than fourteen cyclones. Preferably, the plurality of cyclones is no fewer than eight cyclones. More preferably the plurality of cyclones is no fewer than ten cyclones. Most preferably, the plurality of cyclones is twelve cyclones. Preferably, the ratio of the outer diameter of the dirt container to the outer diameter of each cyclone is no greater than 28:3. More preferably the ratio of the outer diameter of the dirt container to the outer diameter of each cyclone is no greater than 24:3. Preferably, the ratio of the outer diameter of the dirt container to the outer diameter of each cyclone is no less than 12:3. More preferably the ratio of the outer diameter of the dirt container to the outer diameter of each cyclone is no less than 16:3. Most preferably, the ratio of the outer diameter of the dirt container to the outer diameter of each cyclone is about 20:3.

Preferably, the vacuum cleaner is a battery-powered hand-holdable vacuum cleaner comprising a detachable and/or rechargeable battery. This provides a vacuum cleaner that may be readily portable and convenient to use without need to find a mains electrical supply. Preferably, the vacuum cleaner comprises a body with a handle and a dirty air duct located in the path of air flow up stream of the cyclonic separation apparatus. Alternatively, the vacuum cleaner comprises a flexible hose located in the path of the air flow upstream of the cyclonic separation apparatus. Alternatively, the vacuum cleaner comprises an elongate body with a handle at one end and a cleaner head at an opposite end, wherein the cleaner head is located in the path of the air flow upstream of the cyclonic separation apparatus. Preferably, the vacuum cleaner comprises at least one support wheel for supporting the vacuum cleaner upon a floor, wherein the at least one support wheel rotates about the central axis of the cyclonic separation apparatus. The cyclonic separation apparatus is located close to the floor so that fluid communication with the cleaner head is as shortened. This reduces energy loss by reducing the overall length of the air flow path. Preferably, the at least one support wheel defines a cylinder surrounding the dirt container. The cyclonic separation apparatus performs an additional role of axle to the support wheel which makes the vacuum cleaner more compact and reduces the number of parts. Preferably, the elongate body is telescopically extendible so that it can be extended for use and retraced for storage in a much smaller location. Alternatively, the vacuum cleaner is a blower-vac, which is an outdoor garden tool which can perform the role of blowing garden debris for collection and the role of vacuum cleaner for sucking garden debris into a container.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIG. 1, there is shown first embodiment of a hand-held vacuum cleaner2comprising a main body4, a handle6connected to the main body, a cyclonic separation apparatus8mounted transverse across the main body, and a dirty air duct10with a dirty air inlet12at one end. The vacuum cleaner comprises a motor coupled to a fan for generating air flow through the vacuum cleaner and rechargeable cells (not shown) to energise the motor when electrically coupled by an on/off switch14.

Referring toFIGS. 2 to 8, there is shown an arrangement comprising the motor16, the fan18and the cyclonic separation apparatus8. The motor has a drive shaft20with a central axis21. The fan is a centrifugal fan18with an axial input22facing the motor and a tangential output24. The fan has a diameter of 68 mm. The fan is mounted upon the drive shaft at the top of the motor. In use, the motor drives the fan to generate air flow through the cyclonic separation apparatus, as will be described in more detail below. A small portion of the drive shaft20protrudes from the bottom of the motor16. A second fan, comprising a paddle wheel26, is mounted upon the drive shaft20at the bottom of the motor. The motor and the paddle wheel are clad in a cylindrical outer body of the motor, which is often referred to as a “motor can”. In use, the motor turns the paddle wheel to circulate and augment air flow inside the motor can and about the bottom of the motor.

The motor16and the fan18are housed in a motor fan housing27comprising a generally cylindrical body portion28enclosing the motor and a generally circular head portion29enclosing the fan. The head portion29has a larger diameter than the body portion28. The motor fan housing27comprises a perforated end cap30mounted upon the head portion on the opposite side to the body portion. The end cap30protects the fan. The end cap has a circular array of perforations36near where air flow is expelled from the fan. The head portion acts as a baffle to direct air flow from the fan and out the perforations. The body portion has an array of bottom slots32around the bottom of the motor and an array of top slots34about where the drive shaft20protrudes from the top of the motor.

The cyclonic separation apparatus8comprises a pre-fan filter40, a vortex finder assembly50, a generally cylindrical inner wall60, a cyclone seal70, a cyclone assembly80, a cylindrical perforated intermediate wall90, a circular bulkhead100, a tapered funnel110, a transparent generally cylindrical dirt container120, and a circular bowl door130all arranged about the central axis21of the motor drive shaft20.

The pre-fan filter40is an annular shape surrounding the top air flow slots34of the body portion28of the motor fan housing27. The pre-fan filter is enclosed in an annular shell42except where the pre-fan filter communicates with the vortex finder assembly50and with the top air flow slots34of the body portion28. This permits air flow from the cyclonic separating apparatus, through the pre-fan filter and on to the fan.

The vortex finder assembly50comprises planar ring52moulded with twelve hollow cylindrical vortex finders54protruding from one side of the planar ring. Holes56through the vortex finders penetrate the opposite side of the planar ring whereupon the pre-fan filter40is seated. The pre-fan filter40helps to muffle high frequency sounds caused by Helmholtz resonance as air flows through the vortex finder holes56. The vortex finders are arranged in a circular array about the central axis21of the motor drive shaft20. Each vortex finder has its own longitudinal central axis57arranged parallel to the central axis21. The vortex finders may have longitudinal internal ribs (not shown) along the vortex finder holes to further reduce high frequency noise caused by Helmholtz resonance. The longitudinal ribs also tend to straighten air flow in the vortex finder to help reduce energy losses as the air flows into the pre-fan filter40.

The inner wall60is a generally cylindrical shape in two portions of different diameter. The inner wall comprises an annular flange62at an open end of the inner wall, a hollow cylindrical cup64at an opposite closed end of the inner wall, a hollow cylindrical wall66and an annular shoulder68. The flange extends radially outwardly from the open end of the cylindrical wall. The cylindrical wall is located between the flange and the cylindrical cup. The cylindrical wall has a larger diameter than the cylindrical cup. The annular shoulder joins the cylindrical wall to the cylindrical cup. The shoulder is perforated with a circular array of twelve holes69spaced at equi-angular intervals about the central axis21. The annular flange62is connected to an annular roof wall121of the dirt container120.

The vortex finder assembly50is seated in the cylindrical wall66with the planar ring52facing the shoulder68and the vortex finders54protruding through the shoulder's holes68. The pre-fan filer40is nested within the cylindrical wall66. The bottom of the motor fan housing's body portion28is nested within the cylindrical cup64.

The cyclone seal70is perforated with a circular array of twelve holes72spaced at equi-angular intervals about the central axis21. The shoulder68of the inner wall60is seated upon the cyclone seal. The vortex finders54protrude through the seal holes72.

The cyclone assembly80comprises a cylindrical collar82and a circular array of twelve cyclones84surrounded by the collar. The cyclones are spaced at equi-angular intervals about the central axis21. Each cyclone has a hollow cylindrical top part85and a hollow frustro-conical bottom part86depending from the cylindrical top part and terminating with a discharge nozzle87at the bottom of the cyclone.

The shoulder68of the inner wall60is arranged upon the cyclone assembly80with the cyclone seal70interposed therebetween. The collar82has the same outer diameter as, and abuts with, the cylindrical wall66of the inner wall60. The vortex finders54protrude through the holes72in the cyclone seal and into the cylindrical top part85of a respective cyclone84. The only passage through the top of the cyclone84is via its vortex finder54which acts as an air flow outlet port to the pre-fan filter40. Each vortex finder is concentric with its respective cyclone. The plane of each nozzle87is inclined with respect to the central axis57. This helps to prevent dust and dirt particles from re-entry after discharge from the nozzle.

The cylindrical top part85of each cyclone84has an air inlet port88arranged tangentially through the side of the cyclone and proximal the vortex finder54. The twelve air inlet ports are in communication with a distribution chamber170below the collar82around the cyclones84, as is described in more detail below.

The intermediate wall90is arranged upon the cyclone assembly80. The intermediate wall90has the same outer diameter as, and abuts with, the cylindrical collar82.

The bulkhead100is arranged upon, and has approximately the same outer diameter as, the intermediate wall90. The bulkhead100is perforated by a circular array of twelve holes102spaced at equi-angular intervals about the central axis21. The discharge nozzles87of the cyclones84protrude through respective bulkhead holes102. The bulkhead100has a circumferential lip104inclined radially outwardly from the central axis21towards the bowl door130. The lip104protrudes a small way from the intermediate wall90.

The tapered funnel110comprises a hollow circumferential skirt112, a frustro-conical cone114depending from the skirt, and a hollow cylindrical nose116depending from the cone. The skirt is arranged upon, and has approximately the same outer diameter as, the bulkhead. The cone tapers radially inwardly from the bulkhead100towards the bowl door130. A perforated portion118of the skirt protrudes axially rearward from the cone towards the bowl door130.

The generally cylindrical dirt container120comprises the annular roof wall121and a hollow cylindrical exterior wall122with a frustro-conical dirt collection bowl124depending from the exterior wall. The dirt container has a dirty air inlet port126arranged tangentially through the exterior wall122. The dirt container120has a circumferential lip128inclined radially inwardly towards the central axis21and towards the bowl door130. The lip128protrudes a small way in from the transition between the exterior wall and the dirt collection bowl. The motor fan housing's head portion29is nested within the centre of the annular roof wall121. The annular roof wall is detachably connected to an outer circumferential edge138of the exterior wall122. The annular roof wall121may be connected to the exterior wall122and the inner wall60by snap-fit, bayonet fit, interlocking detents, interference fit or by a hinge. A resilient seal or seals made of polyethylene, rubber or a similar elastomeric material is provided around the annular roof wall to ensure airtight connection with the exterior wall.

The bowl door130is detachably connected to an outer circumferential edge132of the dirt collection bowl124. The bowl door abuts the cylindrical nose116thereby dividing the dirt collection bowl into two separate chambers: a generally circular chamber134inside the tapered funnel110and a generally annular chamber162outside the tapered funnel. The bowl door130may be connected to the dirt collection bowl124by snap-fit, bayonet fit, interlocking detents, interference fit or by a hinge. A resilient seal made of polyethylene, rubber or a similar elastomeric material is provided around bowl door130to ensure airtight connection with the dirt collection bowl.

The annular flange62of the inner wall60is in complementary mating relationship with a circular ring123protruding from inside the annular roof wall121. The nose116is in complementary mating relationship with a circular ring140protruding from inside the bowl door130. This ensures that components of the cyclonic separation apparatus8remain concentric with the central axis21when the bowl door is closed.

Between the annular roof wall121and the bowl door130, the various components of the cyclonic separation apparatus8(i.e. pre-fan filter40, vortex finder assembly50, inner wall60, cyclone seal70, cyclone assembly80, intermediate wall90, bulkhead100, tapered funnel110) are arranged upon each other by detachable connection, typically a snap-fit, bayonet fit, interlocking detents, or interference fit. The permits disassembly and reassembly, without tools, of the cyclonic separation apparatus8in order to clean, or replace, its individual components. Resilient seals made of polyethylene, rubber or a similar elastomeric material, or other suitable seal material, are provided around connections of the annular flange62and pre-fan filter shell42with the annular roof wall121. The seals are to ensure airtight connection. The internal diameter of the dirt container120and the bowl door130is large enough to permit removal of the components of the cyclonic separation apparatus8(i.e. pre-fan filter40, vortex finder assembly50, inner wall60, cyclone seal70, cyclone assembly80, intermediate wall90, bulkhead100, tapered funnel110) through either end of the dirt container.

In use, dirty air flows, under the influence of the fan18, in the dirty air inlet12, up the dirty air duct10and into the cyclonic separation apparatus8where dust and dirt entrained in the air flow is separated therefrom. The dust and dirt is collected within the cyclonic separation apparatus. The air flows out the cyclonic separation apparatus8, through the pre-fan filter40, into the motor fan housing27via the top slots34, though the fan18and out the perforations36in the end cap30.

Referring toFIG. 9A, the cyclonic separation apparatus8is divided into a first cyclonic separating unit160, a second cyclonic separating unit150and a distribution chamber170. The first cyclonic separating unit is located in the air flow pathway upstream of the distribution chamber. The distribution chamber is located in the air flow pathway upstream of the second cyclonic separating unit.

The first cyclonic separating unit160comprises the cylindrical dirt container120. The second cyclonic separating unit150comprises the circular array of twelve cyclones84. The dirt container is concentric with the central axis21of the motor drive shaft20. The distribution chamber170is bounded by the hollow cylindrical cup64of the inner wall, cyclone assembly80, intermediate wall90and bulkhead100. The second cyclone unit150received air flow from the first cyclone unit160via the distribution chamber170.

The exterior wall122of the dirt container120has a diameter of approximately 130 mm. The cyclones84have a much smaller diameter than the dirt container. Helical air flow in the cyclones experiences greater centrifugal forces than in the annular chamber. Thus, the cyclones of the second cyclonic separating unit150, when combined, have higher separation efficiency than the dirt container of the first cyclonic separating unit160.

The air flow pathway though the cyclonic separation apparatus8is described in more detail with reference toFIGS. 9B to 9E.

Referring toFIG. 9B, dirty air (triple-headed arrows) flows into the first cyclonic separating unit160via the dirty air inlet port126. The tangential arrangement of the dirty air inlet port126causes the dirty air to flow in a helical path around the cylindrical dirt container120. This creates an outer vortex in the dirt container. Centrifugal forces move the comparatively large dust and dirt particles outwards to strike the side of the dirt container and separate them from the air flow. The dust separated and dirt (D) swirls towards the dirt collection bowl124where it is deposited.

Referring toFIG. 9C, partially-cleaned air (double-headed arrows) flows back on itself to follow an inner helical path closely about the tapered funnel110and towards the cylindrical intermediate wall90. The partially-cleaned air flows through the perforated portion118of the tapered funnel's skirt112largely unimpeded. The circumferential lip104of the bulkhead100and the lip128of the dirt container120converge at a width restriction X in the first cyclonic separating unit160. The width restriction reduces a radial width between the dirt container and the intermediate wall by at least 15 percent The width restriction tapers towards the bowl door130so that air, and entrained dirt, can flow more easily towards the bowl door than in the opposite direction. Thus, the circumferential lips104,128and perforated portion118of the tapered funnel's skirt112catch separated dirt in the bowl124before it can be re-entrained in the partially-cleaned air flow. The partially-cleaned air flows through perforations in the intermediate wall, which filters any remaining large dirt particles, and into the distribution chamber170.

As can be seen inFIG. 5, the air inlet ports88of the twelve cyclones are moulded into the collar82of the cyclone assembly80. The distribution chamber170is in communication with the air inlet ports88of the twelve cyclones84. Referring toFIG. 9D, the partially-cleaned air flow (double-headed arrows) divides itself, in the distribution chamber, evenly between the twelve air inlet ports88from where it flows into the twelve cyclones84of the second cyclonic separating unit150. The air inlet ports88direct the partially-cleaned air flow in a helical path around the vortex finders54. This creates an outer vortex inside each cyclone84. Centrifugal forces move the dust and dirt outwards to strike the side of the cyclone and separate it from the air flow. The separated dust and dirt swirls towards the discharge nozzle87. The internal diameter of the frustro-conical part86of cyclone diminishes as the air flow approaches the nozzle. This accelerates the outer helical air flow thereby increasing centrifugal forces and separating ever smaller dust and dirt particles. The dust and dirt particles exit the nozzle to be deposited inside the part of the bowl124bounded by the tapered funnel110.

Referring toFIG. 9E, cleaned air (single-headed arrows) flows back on itself to follow a narrow inner helical path through the middle of the cyclone84. The cleaned air flows out the internal hole56of the vortex finder54, under the influence of the fan, into the pre-fan filter40. The pre-fan filter40is to remove any fine dust and dirt particles remaining in the air flow after the cyclonic separation apparatus8.

The pre-fan filter is in communication with the motor fan housing27. Cleaned air flows, via the top slots34in the motor fan housing, to the axial input22of the fan18, out the tangential output24of the fan and through the perforations36of the end cap30where it is exhausted from the vacuum cleaner2. Dust and dirt separated by the first and second cyclonic separating units and deposited in the dirt collection bowl124which can be emptied by opening the bowl door130.

Returning toFIG. 7, there are shown three of a total of four motor cooling inlet ports31in the annular roof wall121of the dirt container120. One other motor cooling inlet port is obscured by the end cap30inFIG. 7.

Returning toFIGS. 8, there are shown four vortex finder seals58. Each vortex finder seal forms a webbed collar around three consecutive vortex finders54. Four equiangular spaced small gaps59exist between the four vortex finder seals. The vortex finder seals58seal the connection between the vortex finder assembly50and the inner wall60except where the gaps59are located.

Referring toFIG. 9F, there is shown the pathway of clean motor cooling air (single-headed arrow) flow through the motor16and fan18. The four motor cooling inlet ports are in communication with a first motor cooling passage61abetween the shell42of the pre-fan filter40and the cylindrical wall66of the inner wall60.

Referring toFIG. 9G, there is shown a longitudinal cross-section of a vortex finder54in the region of Detail X ofFIG. 9F. Here, the vortex finder seal58blocks communication between the first motor cooling passage61aand a second motor cooling passage61bbetween the motor fan housing27and the cylindrical cup64of the inner wall60.

Referring toFIG. 9H, there is shown a longitudinal cross-section between two vortex finders54and two vortex finder seals58in the region of Detail X ofFIG. 9F. Here, the gap59between the vortex finder seals58permits communication between the first and second motor cooling passages61a,61b.

Returning toFIG. 9F, in use, clean motor cooling air flows under the influence of the fan though the four motor cooling inlet ports31and along the first motor cooling passage61a, through the gaps59and along the second motor cooling passage61bfrom where it enters the motor fan housing27via the bottom air flow slots32. The motor comprises motor vents17ain the bottom, and motor vents17bin the top, of the motor can to ventilate the interior of the motor. The paddle wheel26circulates and augments motor cooling air about the bottom of the motor. Motor cooling air is drawn, under the influence of the fan, into the bottom motor vents17a, through the interior of the motor, and passes out of the top motor vents17b. The motor is cooled by the motor cooling air flow. The motor cooling air flow pathway joins the cleaned air flow pathway from the cyclonic separation apparatus8around the axial input22of the fan18. The motor cooling air flow is expelled from the tangential output24of the fan and out the perforations36of the end cap30.

The motor cooling inlet ports31are spaced at equiangular intervals about the central axis21. The motor cooling inlet ports are axially aligned with the gaps59between the vortex spaces seals58and with the bottom air flow slots32in the motor fan housing27. This axial alignment is to help minimise any resistance encountered by the motor cooling air flow along the motor cooling passages61a,61b. The bottom motor vents17aare also aligned with the bottom air flow slots32in the motor fan housing27to help minimise any resistance encountered by the motor cooling air flow.

The clean motor cooling air flow pathway is separate from the air flow pathway through the cyclonic separation apparatus8up to the axial input of the fan18. This has particular benefits in vacuum cleaning. Typically, motor speed increases as the fan encounters resistance to volumetric air flow and the pressure across the fan increases accordingly. An example of how this may occur is when the vacuum cleaner is operational and the dirty air inlet contacts carpet, hard floor, curtains or other surface to restrict air flow. Should the air flow path through the cyclonic separation apparatus8become blocked, or impeded, for whatever reason, the motor cooling air flow path would not necessarily be blocked, or impeded. Instead, the increased pressure across the fan18would increase suction through the motor cooling air flow pathway. This has the benefit of increased motor cooling when the motor is working hardest and cooling is needed most.

Referring toFIG. 44, there is shown a table of test data relating to the temperature of the motor16. Two thermocouples were attached to the motor can while the motor was driving the fan18to generate air flow. The cyclonic separation apparatus8was subjected to three separate tests involving different operational conditions: (a) free air flow (dirty air inlet12fully open); (b) maximum power output (air watts) of cyclonic separation apparatus; and (c) sealed suction (dirty air inlet12closed). As the skilled person will appreciate, air watt is a measurement of vacuum power calculated from volumetric flow rate (volume/time) multiplied by suction (force/area) multiplied by a correction factor depending on humidity and atmospheric pressure. The ambient temperature was measured and compared to the motor temperature after ten minutes run time. The same three tests were carried out with four motor cooling inlet ports31and then repeated with one of the four motor cooling inlet ports31closed. The test data clearly reveal the benefits of the motor cooling air flow pathway and the importance of having four motor cooling inlet ports31.

Referring toFIGS. 10 and 11, there is shown a second embodiment of a hand-held vacuum cleaner202comprising a main body204with a main axis205, a handle206, a cyclonic separation apparatus208mounted transverse to the main axis of the main body, and a dirty air duct210with a dirty air inlet212at one end. The vacuum cleaner comprises a motor216coupled to a fan for generating air flow through the vacuum cleaner and rechargeable cells217to energise the motor when electrically coupled by an on/off switch214.

Referring toFIGS. 12 to 16, there is shown an arrangement comprising the motor216, the rechargeable cells217, the fan218, a pre-fan filter240, a cyclonic separation apparatus outlet duct260and the cyclonic separation apparatus208.

The motor has a drive shaft220with a longitudinal central axis221. The fan is a centrifugal fan218with an axial input222facing away from the motor and a tangential output224. The fan has a diameter of 68 mm. The fan is mounted upon the drive shaft at the top of the motor. The cells217are arranged in a circular array about the motor216with the longitudinal axis of the cells parallel to the central axis221, as is shown most clearly inFIGS. 11 and 14. In use, the motor drives the fan to generate air flow through the cyclonic separation apparatus, as will be described in more detail below.

The main body204comprises a central housing226, a motor housing228, a frame230and an end cap232. The fan218is housed in the central housing226. The central housing is connected to the handle206. The motor216and the cells217are housed in the motor housing228. The motor housing is generally elongate to suit the profile of the cells. The end cap230is connected to an opposite end of the motor housing to the fan. The end cap has a circular array of perforations236.

The frame230connects the central housing226to the cyclonic separation apparatus208. One end of the frame supports a pre-fan filter240arranged in front of the axial input222of the fan218. The other end of the frame supports the cyclonic separation apparatus.

The outlet duct260is defined by a generally oval-shaped duct wall262arranged upon the frame230to form the outlet duct between the duct wall and frame. The outlet duct260provides an air flow path between the cyclonic separation apparatus208and the pre-fan filter240. The duct wall is detachable from the frame. The duct wall is transparent to permit visual inspection of the pre-fan filter. The duct wall is removed from the frame if the pre-fan filter needs cleaning or replacement.

The cyclonic separation apparatus208comprises, a vortex finder assembly250, a vortex finder seal270, a cyclone assembly280, a cylindrical perforated intermediate wall290, a circular bulkhead300, a tapered funnel310, a transparent generally cylindrical dirt container320with a longitudinal central axis321, and a circular dirt collection bowl330all arranged about the central axis321of the dirt container320.

The vortex finder assembly250comprises a planar generally circular base252with six hollow cylindrical vortex finders254. Each vortex finder has a central through-hole256and its own longitudinal central axis257. The vortex finders are arranged in a circular array about the central axis321of the dirt container320. Each vortex finder is parallel to the central axis321. The vortex finders protrude from one side of the base. A small portion of each vortex finder also protrudes from the opposite side of the base. The vortex finders may have longitudinal internal ribs (not shown) along the through-holes to help dampen high frequency sounds caused by Helmholtz resonance as air flows through the vortex finder though-holes256.

The cyclone assembly280comprises a generally cylindrical collar282and a circular array of six cyclones284surrounded by the collar. The cyclones are spaced at equi-angular intervals about the central axis321of the dirt container320. Each cyclone has a hollow cylindrical top part285and a hollow frustro-conical bottom part286depending from the cylindrical top part and terminating with a discharge nozzle287at the bottom of the cyclone.

The vortex finder assembly250is arranged upon the collar282of the cyclone assembly280. The vortex finders254protrude into the cylindrical top part285of a respective cyclone284. The only passage through of the top of the cyclone284is via its vortex finder254which acts as an air flow port to the outlet duct260. Each vortex finder is concentric with its respective cyclone. The plane of each nozzle287is inclined with respect to the central axis257. This helps to prevent dust and dirt particles from re-entry after discharge from the nozzle.

The cylindrical top part285of each cyclone284has an air inlet port288arranged tangentially through a side of the cyclone and proximal the vortex finder254. The six air inlet ports are in communication with a distribution chamber370located below the collar282around the cyclones284as described in more detail below.

The intermediate wall290is arranged upon the cyclone assembly280. The intermediate wall290has approximately the same outer diameter as, and abuts with, the cylindrical collar282.

The bulkhead300is arranged upon, and has approximately the same outer diameter as, the intermediate wall290. The bulkhead300is perforated by a circular array of six holes302spaced at equi-angular intervals about the central axis321. The discharge nozzles287of the cyclones284protrude through respective bulkhead holes302. The bulkhead300has a circumferential lip304inclined radially outwardly from the central axis321towards the collection bowl330. The lip304protrudes a small way from the intermediate wall290.

The tapered funnel310comprises a hollow circumferential skirt312, a frustro-conical cone314depending from the skirt, and a hollow cylindrical nose316depending from the cone. The skirt is arranged upon, and has approximately the same outer diameter as, the bulkhead300. The cone tapers radially inwardly from the bulkhead towards the collection bowl330. A perforated portion318of the skirt protrudes axially rearward from the cone towards the collection bowl330.

The generally cylindrical dirt container320comprises a hollow cylindrical exterior wall322with a circular shoulder324extending radially inwardly from the top of the exterior wall. The dirty container has a dirty air inlet port326arranged tangentially through the exterior wall322. The dirty air inlet port communicates with the dirty air duct210. The exterior wall322is rotatingly connected to the frame230to enable the cyclonic separation apparatus208to rotate about its central axis321in relation to the main body204. The dirty air duct210is rotatable with the cyclonic separation apparatus208, as is shown inFIG. 11where the dirty air duct is in a folded position.

The planar base252of the vortex finder assembly250nests within the aperture in the circular shoulder324of the dirt container320. The collar282of the cyclone assembly280abuts the circular shoulder324. The cyclones284are located within the dirt container320.

The dirt collection bowl330is detachably connected to an outer circumferential edge332of the dirt container320. The dirt collection bowl abuts the nose316thereby dividing the dirt container and dirt collection bowl into two separate chambers: a circular chamber334inside the tapered funnel310and a generally annular chamber362outside the tapered funnel. The dirt collection bowl330may be connected to the dirt container's outer circumferential edge by snap-fit, bayonet fit, interlocking detents, interference fit or by a hinge. A resilient seal336made of polyethylene, rubber or a similar elastomeric material is provided around the dirt collection bowl330to ensure airtight connection with the dirt container.

The dirt container320has an annular lip328inclined radially inwardly to the central axis321towards the collection bowl330. The lip328protrudes a small way in from the exterior wall. The lip328is proximal to the bowl330.

The nose316of the tapered funnel310is in complementary mating relationship with a circular ring340protruding from inside the dirt collection bowl330. This ensures that components of the cyclonic separation apparatus208remain concentric with the central axis321of the dirt container320.

In use, dirty air flows, under the influence of the fan218, in the dirty air inlet212, up the dirty air duct210and into the cyclonic separation apparatus208where dust and dirt entrained in the air flow is separated therefrom. The dust and dirt is collected within the cyclonic separation apparatus. The air flows out the cyclonic separation apparatus208, via the through-holes256of the vortex finders, along the outlet duct260, through the pre-fan filter240, through the fan218and over the motor216and batteries cells217via the motor housing228and out the perforations236in the end cap230.

Referring toFIG. 17A, the cyclonic separation apparatus208is divided into a first cyclonic separating unit360, a second cyclonic separating unit350and the distribution chamber370. The first cyclonic separating unit is located in the air flow pathway upstream of the distribution chamber. The distribution chamber is located in the air flow pathway upstream of the second cyclonic separating unit.

The first cyclonic separating unit360comprises the cylindrical dirt container310. The second cyclonic separating unit350comprises the circular array of six cyclones284. The dirt container is concentric with the central axis321of the dirt container. The distribution chamber370is bounded by the collar282, cyclone assembly280, intermediate wall290and bulkhead300. The second cyclonic separating unit350receives air flow from the first cyclonic separating unit360via the distribution chamber370.

The exterior wall322of the dirt container320has a diameter of approximately 120 mm. The cyclones284have a smaller diameter than the annular chamber362. Helical air flow in the cyclones experiences greater centrifugal forces than in the dirt container. Thus, the cyclones of the second cyclonic separating unit350, when combined, have higher separation efficiency than the dirt container of the first cyclonic separating unit360.

The air flow pathway though the cyclonic separation apparatus208is described in more detail with reference toFIGS. 17B to 17F.

Referring toFIG. 17B, dirty air (triple-headed arrows) flows from the dirty air duct210and into the dirt container320via the dirty air inlet port326. The tangential arrangement of the dirty air inlet port326causes the dirty air to flow in a helical path around the dirt container. This creates an outer vortex in the dirt container. Centrifugal forces move the comparatively large dust and dirt (D) particles outwards to strike the side of the dust container320and separate them from the air flow. The separated dust and dirt swirls towards the dirt collection bowl330where it is deposited.

Referring toFIG. 17C, partially-cleaned air (double-headed arrows) flows back on itself to follow an inner helical path closely about the tapered funnel310and towards the cylindrical intermediate wall290. The partially-cleaned air flows through the perforated portion318of the tapered funnel's skirt312largely unimpeded. The circumferential lip304of the bulkhead300and the lip328of the dirt container320converge at a width restriction Y in the first cyclonic separating unit360. The width restriction reduces a radial width between the dirt container and the intermediate wall by at least 15 percent. The width restriction tapers towards the bowl330so that air, and entrained dirt, can flow more easily towards the bowl door than in the opposite direction. Thus, the circumferential lips304,328and perforated portion318of the tapered funnel's skirt312catch separated dirt in the bowl324before it can be re-entrained in the partially-cleaned air flow. The partially-cleaned air flows through perforations in the intermediate wall, which filters any remaining large dirt particles, and into the distribution chamber370.

As can be seen inFIG. 16, the air inlet ports288of the six cyclones are moulded into the collar282of the cyclone assembly280. The distribution chamber370is in communication with the air inlet ports288of the six cyclones284. Referring toFIG. 17D, the partially-cleaned air flow (double-headed arrows) divides itself, in the distribution chamber, evenly between the six air inlet ports288from where it flows into the six cyclones284of the second cyclonic separating unit350. The air inlet ports288direct the partially-cleaned air flow in a helical path around the vortex finders254. This creates an outer vortex inside each cyclone284. Centrifugal forces move the dust and dirt outwards to strike the side of the cyclone and separate it from the air flow. The separated dust and dirt swirls towards the discharge nozzle287. The internal diameter of the frustro-conical body286of cyclone diminishes as the air flow approaches the nozzle. This accelerates the helical air flow thereby increasing centrifugal forces and separating ever smaller dust and dirt particles. The dust and dirt particles exit the nozzle to be deposited inside the part of the bowl330bounded by the tapered funnel310.

Referring toFIG. 17E, cleaned air (single-headed arrows) flows back on itself to follow a narrow inner helical path through the middle of the cyclone284. The cleaned air flows out the internal through-hole256of the vortex finder254, under the influence of the fan.

Returning toFIG. 17F, the cleaned air flows from the vortex finders254into the outlet duct260and to the pre-fan filter240. The pre-fan filter240is to remove any fine dust and dirt particles remaining in the air flow after the cyclonic separation apparatus208and before the fan218. The clean air flows into the axial input222of the fan218and is expelled from the tangential output224of the fan. Pathways in the central housing226direct the clean air flow from the fan over the motor216and cells217, to cool the motor and cells, before the air flows out the perforations236in the end cap232.

Dust and dirt separated by the first and second cyclonic separating units and deposited in the dirt collection bowl330which can be opened for emptying.

Referring toFIG. 18, there is shown a diagrammatical view of the various components of the cyclonic separation apparatus208(vortex finder assembly250, vortex finder seal270, cyclone assembly280, intermediate wall290, bulkhead300, tapered funnel310) located within confines of the outlet duct260, frame230, dirt container320and dirt collection bowl330.

The vortex finder seal270seals the connections between the vortex finder assembly250and the dirt container320in an airtight manner. An outlet duct seal266seals the connection between the frame230and the outlet duct wall262in an airtight manner. The vortex finder seal270and the outlet duct seal266are made of polyethylene, rubber or a similar elastomeric material.

Certain components of the cyclonic separation apparatus208are detachably connected, typically by a snap-fit, bayonet fit, interference fit or by interlocking detents. This permits disassembly and reassembly, without tools, of the cyclonic separation apparatus in order to clean, or replace, its individual components, as is described with reference toFIGS. 19 to 22.

Referring toFIG. 19, there is shown a method of disassembling a first construction of the cyclonic separation apparatus208whereby the outlet duct wall262is detachable from the frame230. The dirt container320is detachable from the frame. The vortex finder assembly is detachable from the frame with, or without, the dirt container. The cyclone assembly280, intermediate wall290, bulkhead300, and tapered funnel310are also detachable, in unison, from the vortex finder assembly. The dirt collection bowl330has a large enough diameter to enable, when the dirt collection bowl is opened, removal of the cyclone assembly280, intermediate wall290, bulkhead300, and tapered funnel310out the dirt container320.

Referring toFIG. 20, there is shown a method of disassembling an alternative construction of the cyclonic separation apparatus208whereby the outlet duct wall262is detachable from the frame230. The dirt container320is detachable from the frame. The vortex finder assembly250, cyclone assembly280, intermediate wall290, bulkhead300, and tapered funnel310are detachable, in unison, from the frame with, or without, the dirt container. The dirt collection bowl330is can be opened for emptying.

Referring toFIG. 21, there is shown a method of disassembling a second alternative construction of the cyclonic separation apparatus208whereby the outlet duct wall262is detachable from the frame230. The dirt container320, vortex finder assembly250, cyclone assembly280, intermediate wall290, bulkhead300, and tapered funnel310are detachable, in unison, from the frame. The dirt collection bowl330can be opened for emptying.

Referring toFIG. 22, there is shown a method of disassembling a third alternative construction of the cyclonic separation apparatus208whereby the outlet duct260(i.e. duct wall262and frame230) is detachable from the frame. The dirt container320remains with the frame. The vortex finder assembly250, cyclone assembly280, intermediate wall290, bulkhead300, and tapered funnel310are removable, in unison, from the frame when the dirt bowl330is opened.

Referring toFIG. 23, there is shown a third embodiment of hand-held vacuum cleaner402comprising a main body404with a handle406, a cyclonic separation apparatus408mounted to the main body, and a dirty air duct410with a dirty air inlet412at one end. The vacuum cleaner comprises a motor coupled to a fan for generating air flow through the vacuum cleaner and rechargeable cells to energise the motor when electrically coupled by an on/off switch414.

Referring toFIGS. 24 to 27, there is shown in more detail the motor416, the rechargeable cells417, the fan418, a pre-fan filter440, a cyclonic separation apparatus outlet duct460and the cyclonic separation apparatus408.

The motor has a drive shaft420. The fan418is mounted upon the drive shaft at the top of the motor. The fan has a diameter of approximately 68 mm. The cells417are arranged about the motor416. In use, the motor drives the fan to generate air flow through the cyclonic separation' apparatus, as will be described in more detail below.

The main body404comprises a central housing426and a frame430. The motor416, fan418and cells417are housed in the central housing426. The central housing is connected to the handle406. The central housing has an array of perforations436near the bottom of the motor. The perforations436are for air flow expelled from the central housing.

The frame430connects the central housing426to the cyclonic separation apparatus408. One end of the frame supports a pre-fan filter440arranged in front of the fan's input. The other end of the frame supports the cyclonic separation apparatus. The cyclonic separation apparatus is rotatingly connected to the frame.

Outlet duct460comprises a duct wall462arranged upon the frame to form a passage between the duct wall and frame approximately 10 mm deep. The outlet duct460provides an air flow path between the cyclonic separation apparatus408and the pre-fan filter440. The duct wall is detachable from the frame. The duct wall is transparent to permit visual inspection of the pre-fan filter. A resilient seal made of polyethylene, rubber or similar elastomeric material is provided around the duct wall to ensure air tight connection with the frame. The duct wall is removed from the frame if the pre-fan filter needs cleaning or replacement.

The cyclonic separation apparatus408comprises a vortex finder assembly450, a cyclone assembly480, and an elongate generally oval-shaped dirt container520with a transparent door530.

The cyclone assembly480comprises a cyclone484and a dirty air inlet port488. The cyclone has a hollow cylindrical body485with the dirty air inlet port and a hollow frustro-conical bottom body486extending from the cylindrical body and terminating with a discharge nozzle487at the narrower end. The air inlet port is arranged tangentially through a side of the cylindrical body. The vortex finder454is arranged inside the cyclone484. The vortex finder is concentric with the cyclone. The deflector fin454is arranged transverse to the path of air flow from the air inlet port. The radially extending short side of the deflector fin abuts the frame430. An apex4541of the deflector fin is proximal to the air inlet port. The hypotenuse side of the deflector fin tapers radially inwardly from the apex to the end of the vortex finder proximal to the discharge nozzle487. There is a small gap of Z approximately 5 mm between the apex and the cylindrical body485of the cyclone484.

The dirt container520is connected to the central housing426at one end and the discharge nozzle487of the cyclone484at the other end. The dirt container comprises a perimeter wall522following the outer perimeter of the elongate generally oval-shaped dirt container and base wall524with a cylindrical pocket526protruding from the base wall into the confines of the dirt container. The cyclone484is in communication with the dirt container where the nozzle487protrudes through the base wall524. The bottom of the motor416is seated inside the pocket526on the opposite side to the dirt container thereby reducing the overall width of the vacuum cleaner by about 20 to 25 mm.

The cyclone484has a curved fin490protruding axially from the discharge nozzle487into the dirt container520. The curved fin circumscribes an arc of about half the circumference of the nozzle facing the pocket526. The ends of the curved fin taper towards the nozzle. The dirt container has a flat fin492protruding from the base wall524. The flat fin extends tangentially from the top of the pocket526to about the middle of the dirt container. The flat fin is generally parallel to an adjacent initial flat portion522aof the perimeter wall522uppermost on the dirt container in normal use.

The door530is detachably connected to the perimeter wall522of the container520. The door530may be connected to the dirt container by snap-fit, interlocking detents, a hinge528or by interference fit with the dirt container's exterior wall. In the example shown, the door is held firmly closed by a spring-loaded latch529. A resilient seal (not shown) made of polyethylene, rubber or a similar elastomeric material is provided around the door530to ensure connection to the dirt container320in an airtight manner. Dust and dirt separated by the cyclonic separation apparatus and deposited in the dirt container520can be emptied by opening the door530. The door is transparent to enable visual inspection of when the dirt container520is full and is in need of emptying.

In use, dirty air flows, under the influence of the fan418, in the dirty air inlet412, up the dirty air inlet duct410and into the cyclonic separation apparatus408where dust and dirt entrained in the air flow is separated therefrom. The dust and dirt is collected within the cyclonic separation apparatus. Air flows out the cyclonic separation apparatus408, via the through-hole456of the vortex finder, along the outlet duct460, through the pre-fan filter440, through the fan418and over the motor416and cells417via the central housing426and out the perforations436in the central housing.

Referring toFIGS. 24,27and28, air flow though the cyclonic separation apparatus408is described in more detail. Dirty air (triple headed arrows) from the dirty air duct410enters the cylindrical body485of the cyclone484via the air inlet port488. The tangential arrangement of the air inlet port488and presence of the triangular deflector fin454protruding from the vortex finder452direct the dirty air to flow in a helical path around the cyclone and towards the frustro-conical body486and then the discharge nozzle. This creates an outer vortex in the cyclone. Centrifugal forces move the comparatively large dust and dirt particles outwards to strike the side of the cyclone and separate them from the air flow. The separated dust and dirt swirls towards the discharge nozzle487and into the dirt container520.

The partially-cleaned air flow (double-headed arrows) is directed by the curved fin490and a proximal curved portion522dof the perimeter wall522to leave the cyclone484in an anti-clockwise upward direction, as viewed inFIG. 24. This helps maintains air flow speed. The flat fin492and the pocket526help to direct the partially cleaned air flow to follow an elongate circuit about the perimeter wall522of dirt container520, similar in shape to a two-pulley belt drive wherein the discharge nozzle487simulates a pulley at one end and the pocket526simulates a pulley at the opposite end. For example, the elongate circuit of air flow begins outbound away from the discharge nozzle in proximity to the initial flat portion522bof the perimeter wall522and is redirected inside a distal curved portion522cof the perimeter wall522to turn around the pocket526and continue inbound towards the discharge nozzle adjacent to a further flat portion522dof the perimeter wall lower most on the dirt container in normal use. An axis of elongation of the elongate circuit runs approximately through the centres of the discharge nozzle and the pocket. The flat fin and the pocket prevent the bulk of the dust and dirt particles (D) from dropping out of the circulating air flow before being deposited upon the further flat portion522dof the perimeter wall at the bottom of the dirt container. The perimeter wall522has a generally lozenge shape in cross-section parallel to the base wall524. The initial flat portion522aand the further flat portion522cof the perimeter wall taper inwardly and away from the distal curved portion522bof the perimeter wall. This encourages deposit of dust and dirt around the pocket end of the dirt container where there is more space than at the opposite discharge nozzle end of the dirt container. Also, the curved fin490acts as an obstacle to laminar air flow inbound to the discharge nozzle. The air flow is forced to deviate around the curved fin. This disruption of laminar air flow provokes deposit of any remaining entrained dirt and dust (D) in the dirt container. As such, the shape of the perimeter wall522, the flat fin492, the pocket526and the curved fin490combine to help to separate any remaining dust and dirt from air flow path destined for the pre-fan filter440. This increases sustained performance of the vacuum cleaner502.

Having deviated past the curved fin490, clean air flow (single-headed arrows) turns back on itself and, under the influence of the fan, flows in a narrow inner helical path into the vortex finder's through-hole456from where it leaves the cyclonic separation apparatus408and enters the outlet duct460.

Referring toFIGS. 29 to 38, there is shown a variety of battery-powered vacuum cleaners with the motor16, fan18and cyclonic separation apparatus8arrangement of the first embodiment. The arrangement is, in all examples, arranged with the central axis21of the drive shaft20orientated transverse a main axis of the main body of the vacuum cleaner. In particular, there is shown a hand-holdable vacuum cleaner602with pivotable dirty air duct610; a hand-holdable vacuum cleaner702connected to a cleaning nozzle712by a flexible hose710to resemble a small cylinder vacuum cleaner; and a vacuum cleaner802with an elongate body806, a support wheel807and a cleaner head812to resemble an upright vacuum cleaner, also commonly referred to as a “stick-vac”.

Referring toFIGS. 29 to 32, the hand-holdable vacuum cleaner602comprises a main body604with a main axis605and a handle606. The motor16, fan18and cyclonic separation apparatus8of the first embodiment are rotatingly connected to the main body604at the annular roof wall121of the dirt container120. The central axis21of the cyclonic separation apparatus is orientated at a right angle (i.e. transverse) to the main axis of the main body. The vacuum cleaner602comprises a battery pack900of rechargeable cells917to energise the motor16when electrically coupled by an on/off switch. The dirty air duct610is connected to the air inlet port126.

Referring in particular toFIG. 31, the battery pack900has a curvilinear cross-sectional profile with a curvilinear inner wall902shaped to fit around the cylindrical dirt container120. The battery pack900has a pair of electrical contacts904on a curvilinear outer wall906so that the cells may be recharged in situ. The battery pack is detachably connected to the dust container120. The battery pack may be detached from the duct container to enable replacement, or external recharging of the cells, if necessary. The cells have a generally cylindrical shape. Longitudinal axes of cells are arranged parallel to the central axis21of the motor16.

The dirty air duct610and the battery pack900are rotatable, with the cyclonic separation apparatus8, about the central axis21through an arc subtending 210 degrees from a folded position. This allows the vacuum cleaner602to be pointed in different directions, whilst a user is able to hold the vacuum cleaner in the same orientation. The vacuum cleaner may be used to access awkward spaces and can be held more comfortably by orientating the main axis605of the main body604to suit the user and adjusting the position of the dirty air inlet612to point at a surface to be cleaned, rather than orientating the main axis to best suit the surface to be cleaned and requiring the user to hold the vacuum cleaner in whichever orientation this demands.

FIGS. 29 and 30show the vacuum cleaner602in the folded position where the dirty air duct is folded at zero degrees under the handle606for compact storage. The battery pack900is rotated to the diametrically opposite side of the dirt container120. The vacuum cleaner may be cradled by a battery charger916in the upright position shown inFIG. 29. This allows the vacuum cleaner to be stood in a small surface area and without excessive height because the dirty air duct is folded under the handle. Arranged like this, the vacuum cleaner is easier to grab. The vacuum cleaner's centre of gravity is lowered by the battery pack thus making the upright position more stable. Moreover, the cells917are electrically coupled by the electrical contacts904to the battery charger916for recharging in the upright position.

FIG. 32shows the vacuum cleaner602in an extended position. The dirty air duct610is rotated through 180 degrees from the folded position and is ready for use. The dirty air duct610has been telescopically extended to double its length. The battery pack900occupies a gap616between the handle606and the dirt container120. The battery pack is relatively heavy and its location in the gap616moves the vacuum cleaner's centre of gravity closer to the handle. This improves the ergonomics of the vacuum cleaner.

Referring toFIGS. 33 and 34, the hand-holdable vacuum cleaner702comprises a body704with a handle706. The motor16, fan18and cyclonic separation apparatus8is connected to the body704at the annular roof wall121of the dirt container120. The vacuum cleaner702comprises a pack910of rechargeable cells. The cells are to energise the motor16when electrically coupled by an on/off switch. The air inlet port126is connected to one end of the flexible hose710. The cleaning nozzle712is connected to the other end of the flexible hose.

The battery pack910has a curvilinear inner wall902which is shaped to cradle the cylindrical dust container120. The battery pack is detachably connected to the dust container120. The cells may be recharged in situ. The battery pack may be detached from the dirt container to enable replacement, or external recharging of the cells, if necessary. The battery pack has a pair of feet912arranged to support the vacuum cleaner702in a stable manner when placed upon a flat surface. The cells have a generally cylindrical shape. Longitudinal axes of the cells are arranged parallel to the central axis21of the motor16.

FIGS. 32 and 34show a compact configuration of the vacuum cleaner702. The flexible hose710is wrapped around the dirt container120and under the battery pack910via rebates914in the battery pack feet912. The cleaning nozzle712is cradled by the handle706. The handle is moulded in plastics material with natural resilience. The cleaning nozzle is gripped by the handle. The cleaning nozzle can be readily detached from the handle for use in vacuum cleaning.

Referring toFIGS. 35 and 37, the vacuum cleaner802comprises the elongate body804. The elongate body is telescopic. The elongate body has a handle806at one end and a bracket805at the other end. The motor16, fan18and cyclonic separation apparatus8of the first embodiment are rotatingly connected to the bracket805at the annular roof wall121of the dirt container120. The bracket arches around one side of the dirt container so that the latter may be connected transverse to the elongate body. The support wheel807surrounds the dirt container120. The support wheel is supported for rotation about the dirt container by a bearing809. The air inlet port126is connected to one end of the dirty air duct810. The cleaner head812is connected to the other end of the dirty air duct810. The cleaner head is pivotable in relation to the dirt container about a longitudinal axis8100of the dirty air duct. The dirty air duct is arranged tangentially to the dirt container.

The vacuum cleaner comprises a battery pack900of rechargeable cells917to energise the motor16when electrically coupled by an on/off switch. Referring toFIG. 37, the battery pack900has a curvilinear inner wall902which is shaped to embrace the support wheel807and part of the cylindrical dirt container120. The battery pack is detachably connected to the bracket805. The cells917may be recharged in situ. The battery pack may be detached from the bracket to enable replacement, or external recharging of the cells, if necessary. The cells have a generally cylindrical shape. Longitudinal axes of the cells are arranged parallel to the central axis21of the motor16.

Returning toFIG. 35, there is shown the vacuum cleaner802, prepared for use, with the support wheel807and the cleaning head812upon a floor and the elongate body804fully extended. The support wheel807is arranged about the midpoint of the axial length of the dirt container. The diameter of support wheel807is approximately the same as the axial length of the dirt container120so that the elongate body can be rocked from side to side by about 45 degrees each way and the vacuum cleaner802can be steered with ease.

Returning toFIG. 37, there is shown the vacuum cleaner with the elongate body804fully retracted to approximately a quarter of the elongate body's extended length. The vacuum cleaner's overall length when the elongate body is extended is at least double the vacuum cleaner's overall length when the elongate body is retracted. The vacuum cleaner802is prepared for storage in a kitchen cupboard when the elongate body is retracted. The elongate body may be locked in its retracted and extended positions. The skilled person will appreciate that any suitable locking system will suffice, like, for example, a spring-loaded detent interlockable with holes along the elongate body corresponding to the retracted position, the extended position and any intermediate position therebetween.

Referring toFIG. 38, there is shown in perspective the shape of the battery pack900and, in particular, the curvilinear inner wall902which is to embrace, or connect to, the outside of the dirt container120of the cyclonic separation apparatus8.

Referring toFIGS. 39 and 40, there is shown the battery pack900along cross-section XXXVIII-XXXVIII. Commercially available rechargeable cells may be cylindrical in shape.FIG. 39shows five cylindrical cells917stacked in a curved array to conform to the internal cavity of the curvilinear cross-section profile of the battery pack. Also commercially available are plate rechargeable cells927composed of flexible anode and cathode plates, or sheets, interposed by a polymer electrolyte material and separator material. The anode sheets are electrically connected to the positive cell terminal and the cathode sheets are electrically connected to the negative cell terminal, and those sheets can be connected in series or in parallel to form a battery pack. These plate cells are flexible and they can be stacked upon each other.FIG. 40shows three plate cells927stacked upon each other and curved to conform to the internal cavity of the curvilinear cross-section profile of the battery pack.

Referring toFIGS. 41 to 43there is shown an annular battery pack920in cross-section which is adapted to surround the dirt container120of the cyclonic separation apparatus8with a hollow cylindrical inner surface922. The annular battery pack has a cylindrical inner wall922and a cylindrical outer wall926.

FIG. 41shows 12 cylindrical cells917arranged in a circular array to conform to the internal cavity of the annular cross-sectional profile of the annular battery pack920.

FIG. 42shows three plate cells927stacked upon each other and curved into a hollow cylindrical shape to conform to the internal cavity of the annual cross-section of the annular battery pack920.

FIG. 43shows five plate cells927wound into a hollow cylindrical shape to conform to the internal cavity of the annular cross-section of the annular battery pack920.

The curved plate cells927improve use of the internal cavity of the battery packs920by eliminating the gaps which naturally exist between the cylindrical cells917. This results in a more compact design of battery pack with reduced packaging and a higher energy density.

The curvilinear or cylindrical inner walls902,922of the curvilinear battery pack900,910and the annular battery pack920embrace, or attach themselves to, the dirt container120. This facilitates new design choices for accommodating cells in a compact manner.

The skilled addressee will appreciate that the rechargeable cells can be any type of energy accumulator, including rechargeable Lithium Ion, Nickel Metal Hydride or Nickel Cadmium rechargeable cells, for driving the electric motor16,216,416.

The skilled addressee will appreciate that the specific overall shapes and sizes of the arrangements comprising the motor16,216,416the fan18,218,418and the cyclonic separation apparatus8,208,408can be varied according to the type of vacuum cleaner in which either of the arrangements is to be used. For example, the overall length or width of each arrangement, and, in particular, the cyclonic separation apparatus, can be increased or decreased with respect to its diameter, and vice versa.

In particular, the hand-holdable vacuum cleaner702ofFIGS. 33 and 34can be modified to comprise the motor216, fan218and cyclonic separation apparatus208of the embodiment by modifying the form of the battery pack910to suit the underside of the dirt container320. The flexible hose710would need extension to be wrapped around the dirt container320and the central housing226and motor housing228.

Further, the hand-holdable vacuum cleaner802ofFIGS. 35 to 38can be modified to comprise the motor216, fan218and cyclonic separation apparatus208of the second embodiment by substituting the central housing226and motor housing228for the main bracket805. This could be done by attaching the elongate body804directly to the central housing226in place of the handle206and the bracket805. The cyclonic separation apparatus outlet duct260would need extension to create enough clearance for the support wheel807and bearing809to surround the dirt container320.

The motor16,216,416discussed above is a typically a brushed d.c. motor with its drive shaft20,220,420directly coupled to the centrifugal fan18,218,418. The motor's drive shaft has a rotational speed within a range of 25,000 and 40,000 revolutions per minute (rpm). A centrifugal fan with a rotational speed within this range has an outer diameter approximately double the outer diameter of the motor can in order to have sufficient tip speed to generate the required volumetric flow rate through the cyclonic separation apparatus. The skilled person will appreciate that the motor16,216,416can be a d.c. motor, an a.c. motor, or an asynchronous multi-phase motor controlled by an electronic circuit. A permanent magnet brushless motor, a switched reluctance motor, a flux switching motor, or other brushless motor type, may have a high rotational speed within a range of 80,000 to 120,000 rpm. If such a high speed motor were used then the fan diameter could be at least halved and yet still generate the required volumetric flow through the cyclonic separation apparatus because the fan's tip speed would be so much higher. This would make the fan's outer diameter the same as the motor can's outer diameter and could possibly make it less than the motor can's outer diameter if the motor operates at around the upper end of the high rotational speed range. A smaller diameter fan operating within this range of high rotational speeds would typically be an impeller although it may be an axial fan or a centrifugal fan. The outer profile of the smaller fan coupled to the drive shaft of the high rotational speed motor would have a generally cylindrical outer profile. This provides additional flexibility in the layout of the cyclonic separation apparatus.

In a modification of the first or second embodiment of a cyclonic separation apparatus8,208which is not shown in the drawings, the cyclones84,284can be rearranged to accommodate a high rotational speed permanent magnet brushless motor, a switched reluctance motor or a flux switching motor coupled to a fan which is coaxial with the motor and has an outer diameter substantially the same as or less than the outer diameter of the motor. The generally cylindrical outer profile of high speed motor and fan can be sunk into the cyclonic separation apparatus amongst the cyclones and clustered into a generally circular array. Air flow can be directed to the axial input of the fan and expelled from the tangential output of the fan by a baffle. The high speed motor and fan may be located on the periphery of the circular array in which case air flow from the fan may be expelled from one side of the circular array and directed out of the cyclonic separating apparatus. The high speed motor and fan may be nested near, or at, the middle of the circular array in which case air flow from the fan may be expelled from one end of the circular array and directed out of the cyclonic separating apparatus. If the high speed motor and fan were nested in a circular array of cyclones inclined with respect to a central axis, like, for example, a modified version of the cyclones disclosed by GB 2 440 110 A, then air flow from the fan may be expelled from one end of the circular array of cyclones or through gaps between the cyclones.