SUCTION NOZZLE

Abstract

A suction nozzle for a vacuum cleaner that includes an agitator defining a longitudinal axis and being rotatable about said longitudinal axis; a motor configured to rotate the agitator; and a coolant path extending from an inlet to an outlet. The coolant path is configured to direct an air flow from the inlet, past the motor and subsequently over or through the motor, to the outlet.

Claims

1. A suction nozzle for a vacuum cleaner, the suction nozzle comprising: an agitator defining a longitudinal axis and being rotatable about the longitudinal axis; a motor configured to rotate the agitator; and a coolant path extending from an inlet to an outlet, wherein the coolant path is configured to direct an air flow from the inlet, past the motor and subsequently over or through the motor, to the outlet.

2. The suction nozzle of claim 1, wherein the coolant path is configured to prevent the flow of air from contacting the agitator.

3. The suction nozzle of claim 1, wherein the coolant path is configured to prevent the air flow from contacting the motor as the air flow is directed past the motor.

4. The suction nozzle of claim 1, wherein the motor is received at least partially inside the agitator.

5. The suction nozzle of claim 4, wherein the coolant path is configured to direct the air flow past the motor between the motor and the agitator.

6. The suction nozzle of claim 1, wherein: the coolant path is configured to prevent the flow of air from contacting the agitator, and to prevent the air flow from contacting the motor as the air flow is directed past the motor; the motor is received at least partially inside the agitator; the coolant path is configured to direct the air flow past the motor between the motor and the agitator; the suction nozzle further comprises two concentric sleeves; the sleeves are at least partially received inside the agitator; the motor is at least partially received inside the sleeves; and the coolant path is configured such that the air flow runs in between the two sleeves past the motor, and runs inside the two sleeves over or through the motor.

7. The suction nozzle of claim 1, wherein the suction nozzle further comprises a gear assembly via which the motor can rotate the agitator, and the coolant path is further configured to direct the air flow over or through the gear assembly.

8. The suction nozzle of claim 7, wherein: the gear assembly is an epicyclic gear train comprising a sun gear, one or more planet gears mounted on a carrier, and a ring gear; and the coolant path is configured to direct the air flow over the ring gear of the gear assembly.

9. The suction nozzle of claim 7, wherein the coolant path is configured to direct the air flow over or through the gear assembly before directing the flow of air over or through the motor.

10. The suction nozzle of claim 1, wherein the coolant path is configured to direct the air flow into the agitator at an axial end of the agitator, and out of the agitator at the same axial end.

11. The suction nozzle of claim 1, wherein the coolant path is configured to direct the air flow to run along at least 70% of the axial length of the agitator.

12. The suction nozzle of claim 1, wherein the inlet is configured such that air entering the inlet to form the air flow is taken from outside the suction nozzle.

13. The suction nozzle of claim 1, wherein the coolant path comprises a passage of annular cross section relative to the direction of movement of the air flow therethrough.

14. The suction nozzle of claim 1, wherein the agitator is removable from the suction nozzle.

15. A vacuum cleaner comprising a suction nozzle, the suction nozzle comprising: an agitator defining a longitudinal axis and being rotatable about the longitudinal axis; a motor configured to rotate the agitator; and a coolant path extending from an inlet to an outlet, wherein the coolant path is configured to direct an air flow from the inlet, past the motor and subsequently over or through the motor, to the outlet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[0050] FIG. 1 is a perspective view of a vacuum cleaner according to an embodiment of the invention;

[0051] FIG. 2 is a perspective view of a cleaner head of the vacuum cleaner of FIG. 1;

[0052] FIG. 3 is a perspective view of the cleaner head of FIG. 2, from underneath;

[0053] FIG. 4 is a cut-away view of the cleaner head of FIGS. 2 and 3, viewed generally from the front;

[0054] FIG. 5 is a cut-away view of the cleaner head, viewed generally from the top;

[0055] FIG. 6 is a cross sectional view of the cleaner head, taken through a gear assembly thereof;

[0056] FIG. 7 is a cross sectional view of the cleaner head, taken through a motor thereof;

[0057] FIG. 8 is a cross sectional view of the cleaner head, taken through a motor support thereof;

[0058] FIG. 9 is a perspective view of the cleaner head, with a top housing, agitator, inner sleeve and outer sleeve removed;

[0059] FIG. 10 is perspective view of the assembly shown in FIG. 9, with the inner sleeve in place;

[0060] FIG. 11 is a perspective view of the assembly shown in FIG. 10, with the outer sleeve in place;

[0061] FIG. 12 is a perspective view of the cleaner head, with an end cap detached therefrom; and

[0062] FIG. 13 is a further perspective view of the cleaner head with the end cap detached therefrom.

DETAILED DESCRIPTION OF THE INVENTION

[0063] Throughout the description and drawings, corresponding reference numerals denote corresponding features.

[0064] FIG. 1 shows a vacuum cleaner 2 according to an embodiment of the invention. The vacuum cleaner 2 of this embodiment is an upright vacuum cleaner. It has a rolling assembly 4 which carries a suction nozzle 6 in the form of a cleaner head, and an upright body 8. The upright body 8 can be reclined relative to the suction nozzle 6, and includes a handle 10 for manoeuvring the vacuum cleaner 2 across the floor. In use, a user grasps the handle 10 and reclines the upright body 8 until the handle 10 is disposed at a convenient height. The user can then roll the vacuum cleaner 2 across the floor using the handle 10 in order to pass the suction nozzle 6 over the floor and pick up dust and debris therefrom. The dust and debris is drawn into the suction nozzle 6 by a suction generator in the form of a motor-driven fan (not visible) housed on board the vacuum cleaner 2, and is ducted in conventional manner under the fan-generated suction pressure from an outlet duct 12 of the suction nozzle 6 to a cyclonic separating apparatus 14 where dirt is separated from the air. The relatively clean air is then exhausted back to the atmosphere.

[0065] The suction nozzle 6 is shown in isolation in FIGS. 2 and 3. It has a housing 16 made up of an upper housing 16a, lower housing 16b, front housing 16c, rear housing 16d and two end walls 16e, 16f. The upper and lower housings 16a, 16b and the end walls 16e, 16f of the housing 16 co-operatively define a suction chamber 18 which is in fluid communication with the outlet duct 12. The lower housing 16b and end walls 16e, 16f of the housing 16 co-operatively define a sole plate 20 which has a set of wheels 21 and a suction opening 22. An agitator 24 in form of brush bar is positioned inside the suction chamber 18. The brush bar 24 defines a longitudinal axis 26 is rotatable about its longitudinal axis within the suction chamber 18. The agitator 24 comprises two generally helical arrays of bristles (not shown), each of which is received by and projects from a generally helical groove 27 in the agitator.

[0066] The suction nozzle has a pair of large debris slots 28 in the sole plate 20, and a pair of bleeds 30 which run through the front housing. The large debris slots 28 and bleeds 30 can be opened and closed by a slidable switch 32 provided on the front housing 16c, but the function and structure of these components is not material to the present invention and therefore will not be described in detail.

[0067] In use, a user passes the suction nozzle 6 across a surface to be cleaned. The sole plate 20 engages the surface and air is sucked into the suction chamber 18 through the suction opening 22. The air is then drawn out of the suction chamber 18 and into the rolling assembly 4 through the outlet duct 12. When the suction nozzle 6 is resting on a hard surface such as a laminate floor, the suction nozzle 6 is supported by the wheels 21. However, when the suction nozzle 6 is resting on a carpeted surface, the wheels 21 sink into the pile of the carpet and the suction opening 22 is therefore positioned further down. This allows carpet fibres to protrude through the suction opening 22, whereupon they are disturbed by the rotating agitator 24 so as to loosen dirt and dust therefrom. The mechanism by which the agitator 24 is driven will now be described, with reference to FIGS. 4-11 in combination with FIGS. 1-3.

[0068] The agitator 24 has a substantially tubular part 24a in which the grooves 27 are provided, and a closed end part 24b. A motor 34 for rotating the agitator 24 about its longitudinal axis 26 is positioned fully within the agitator, more particularly approximately centrally within the tubular part 24a. The motor 34 is of conventional design and therefore will not be described in detail. The motor 34 drives the agitator via a gear assembly 36 in the form of an epicyclic gear train which comprises a sun gear 38, three planet gears 40 mounted a carrier 42, and a ring gear 44. The ring gear 44 is fixedy mounted to a casing 46 of the motor 34 by a gear adaptor 48, and the sun gear 38 is fixedly mounted on an output shaft 50 of the motor 34. The carrier 42 is rotatably mounted on the output shaft 50 via a bearing 52, and is fixedly mounted to a drive dog 54. The drive dog 54 has an external array 56 of teeth which mesh with an internal array of complementary teeth provided on the agitator 24. Accordingly, when the motor 34 is energised, the output shaft 50 and thus the sun gear 38 rotates and the ring gear 44 remains stationary. The planet gears 40 orbit the sun gear 38 and therefore the carrier 42, and thus the drive dog 54 and agitator 24, rotate as well. The gear assembly 36 gears down the drive from the motor 34 so that the agitator 24 rotates at a lower speed, but under higher torque, than the output shaft 50 of the motor.

[0069] The gear adaptor 48 extends circumferentially around the motor and ring gear, and has a circumferentially-spaced set of arms 60 with gaps 62 therebetween. The gaps 62 extend radially inwards through the gear adaptor and terminate at positions axially aligned with breather holes 64 in the front of the casing 46 of the motor 34. An o-ring 66 is positioned between the gear adaptor 48 and the casing 46 of the motor 34. The axial end of the ring gear 44 opposite to the motor 34 is covered by an elastomeric cover 68. Like the gear adaptor 48, the cover 68 extends circumferentially around the ring gear 44. These features of the gear adaptor 48 and cover 68 are more clearly visible in FIGS. 4-6 and 9.

[0070] The motor 34 is mounted to a motor support 72 via a motor adaptor 74 and a sealing member 76. The motor support 72 is attached to a mounting member 78 via a sealing member 80, and the mounting member 78 is attached to the end wall 16e of the housing 16 via a sealing member 82. Accordingly, the motor 34 is mounted to one end of the suction nozzle 6, and engages the agitator 24 (via the gear assembly 36 and drive dog 54) at the opposite end of the suction nozzle.

[0071] The motor adaptor 74 is generally cup-shaped, with its open end abutting the casing 46 of the motor 34 so that inside space 84 of the motor adaptor 74 is in communication with breather holes 86 in the rear of the casing 46 of the motor 34. The closed end of the motor adaptor 75 has an aperture 88 in communication with the inside space 84.

[0072] The motor support 72 is generally cylindrical, and has a hollow interior which defines an inflow chamber 90, an outflow chamber 92 and a wiring chamber 94. Each of these chambers 90, 92, 94 is open at each axial end of the motor support 72. The motor support 72 also has a radial aperture 96 in fluid communication with the inflow chamber 90.

[0073] The mounting member 78 and sealing member 82 co-operatively define a generally L-shaped channel 98 with a generally radially-extending arm 100 and a generally longitudinally-extending arm 102. Arm 100 has an axially-facing aperture 101 therein. Arm 102 is positioned within a duct 104 defined in the lower housing 16b. The duct 104 runs generally axially and terminates at the outlet 12. The mounting member 78 and sealing member 82 also define an inlet chamber 106 which is separate to the L-shaped channel 98, and which is positioned in fluid communication with a vent 108 in end wall 16e. The mounting member 78 and sealing member 82 also define an aperture 110 in fluid communication with the inlet chamber 106.

[0074] The wiring chamber 94 of the motor support 72 is closed (in this case sealed) at one end by sealing member 76, and at its other end by sealing member 80. The wiring chamber 94 is therefore air-tight. Wiring 112 for transmitting power to the motor 34 runs through the wiring chamber 94, and through a ferrite toroid 114 for suppressing electrical noise that is also positioned inside the wiring chamber.

[0075] The inflow chamber 90 of the motor support 72 is sealed closed at one end by sealing member 76, but at its other end is sealed against the aperture 110 in the mounting member 78 and sealing member 82. The inflow chamber 90 is therefore in fluid communication with the inlet chamber 106.

[0076] One end of the outflow chamber 92 is sealed against the aperture 88 of the motor adaptor 74 by a duct 115 of the sealing member 76. The outflow chamber 92 is therefore in fluid communication with the inside space 84 of the motor adaptor 74. The other end of the outflow chamber 92 is sealed against the aperture 101 in the radially-extending arm 100 of the L-shaped channel 98 by sealing member 80. The outflow chamber 92 is therefore also in fluid communication with the duct 104 in the lower housing 16b.

[0077] The suction nozzle 6 also has an inner sleeve 116 and an outer sleeve 118 positioned generally concentrically with respect to one another. The sleeves 116, 118 are received inside the agitator 24, and the motor is received within the sleeves. The sleeves 116, 118 extend circumferentially around the motor 34 and gear assembly 36, and are concentrically positioned inside the tubular part 24a or the agitator 24. The inner sleeve 116 is supported on sealing member 76, an o-ring 120 positioned around the motor adaptor 74, an o-ring 122 positioned around the gear adaptor 48, and the elastomeric cover 68. The outer sleeve 118 is supported on a sealing member 124 mounted on the motor support 72, and an o-ring 126 positioned around the inner sleeve 116. The sleeves 116, define a generally annular gap 128 therebetween. As discussed in more detail later, the gap 128 forms a passage of annular cross section (relative to the direction of movement of the air flow therethrough). This passage is positioned circumferentially around the agitator axis 26, and circumferentially around the motor 34 and the gear assembly 36.

[0078] The inner sleeve 116 has an inlet aperture 130 at one end, a circumferential array of outlet apertures 132 at the other end, and a circumferential array of longitudinal ridges 134. The inner sleeve 116 also provides additional support for the carrier 42 via a bearing 135. The ridges 134 project radially outwards towards the outer sleeve 118, but are nonetheless radially spaced therefrom. The inlet aperture 130 of the inner sleeve 116 is positioned in alignment with the aperture 96 in the inflow chamber 90 of the motor support 72. Accordingly, the gap 128 between the sleeves 116, 118 is in fluid communication with the inflow chamber 90. Each outlet aperture 132 is positioned in alignment one of the gaps 62 in the gear adaptor 48, therefore the gap 128 is also in fluid communication with the breather holes 64 in the front of the casing 46 of the motor 34.

[0079] The suction nozzle 6 defines a coolant path configured to direct an air flow from an inlet, past the motor and subsequently over or through the motor, to an outlet. In this case, the vent 108 in the end wall 16e forms the inlet of the coolant path, the duct 104 in the lower housing 16b forms the outlet, and the coolant path directs the air flow past the motor and subsequently through the motor. The coolant path runs through the vent 108, into the inflow chamber 109 through the inlet chamber 106, and into the gap 128 between the sleeves 116, 118. The air flow is then directed past the motor, axially along the gap 128 between the sleeves. The air then flows out of the gap 128, over the gear assembly 36 and through the motor 34 inside of the sleeves 116, 188. It then flows into the outflow chamber 92, through the L-shaped channel 98 and duct 104, and exits the suction nozzle 6 through the outlet 12. This will be described in more detail below.

[0080] When the vacuum cleaner 2 is in use, the suction generator reduces the pressure at the outlet 12. This, in turn, reduces the pressure inside the suction chamber 18 so as to draw air into it through the suction opening 22. Since the duct 104 is in fluid communication with the outlet 12, the pressure in the duct is also reduced. This acts to draw an air flow (in this case a separate air flow to the dirt-entraining air entering the suction chamber 18 through the suction opening 22) through the coolant path. The air flow enters the coolant path through the vent 108 and into the inlet chamber 106 that is defined by the mounting member 78 and sealing member 83. The vent 108 is positioned on an external surface of the suction nozzle 6, and therefore the air flow is taken from the relatively clean air outside the suction nozzle. In contrast, if the air flow was taken from the suction chamber 18 then dirt entrained therein would be passed through the coolant path, potentially clogging the coolant path and/or damaging the motor. The vent 108 is also positioned at an upper region of the suction nozzle 6 so as to space it apart from the surface being cleaned and thereby reduce the chances of the air flow entering the vent 108 entraining dirt resting on the surface.

[0081] From the inlet chamber 106, the air flow is drawn into the inflow chamber 90 through the aperture 110, and then into the gap 128 through the radial aperture 96 of the motor support 72 and the inlet aperture 130 in the inner sleeve 116. The air flow is prevented from leaking out of the coolant path between the inner sleeve 116 and motor adaptor 74 by the sealing member 76 engaging the inner sleeve. In some situations some of the air flow may leak out between the inner sleeve 116 and the motor support 72, however any such air would nonetheless be directed into the gap 128 by sealing member 124.

[0082] Upon entering the gap 128 through the inlet aperture 130 of the inner sleeve 116, the air can flow circumferentially around the gap, between the ridges 134 and the outer sleeve 118. The air flow then flows axially along the gap 128, between the motor 34 and the agitator 24, past the motor while circumferentially distributed around it. As the air flow passes the motor 34, it absorbs some heat therefrom and therefore has a cooling effect on the motor. The air flow also absorbs heat from the agitator 24 as the air flows along the gap 128 (and to a lesser extent as the air flows along the inflow chamber 90), ensuring that the agitator remains cool enough to be touched by the user.

[0083] When the air flow running axially along the gap 128 reaches the outlet apertures 132, it has run along around 70% of the total axial length of the agitator 24 (around 20% of the length of the agitator in the inflow chamber 90, and around 50% if the length of the agitator in the gap 128). This relatively large proportion means that the cooling influence of the air flow is experienced by a larger proportion of the agitator 24. This is particularly true for the proportion of the axial length of the agitator 24 along which the air passes whilst in the gap 128, since the air flow is positioned closer to the agitator while in the gap.

[0084] Once the air flow has reached the outlet apertures 132 of the inner sleeve 116, the air flow runs over the parts of the ring gear 44 that are left exposed by the cover 68 and the arms 60 of the gear adaptor 48, and into the gaps 62 of the gear adaptor. As the air flow passes over the ring gear 44, it absorbs heat therefrom and therefore cools the ring gear 44 (and thus the gear assembly 36 as a whole). Air is prevented from leaking out of the coolant path past the outlet apertures 132 in between the sleeves 116, 118 by o-ring 126, and is prevented from leaking out between the inner sleeve 116 and the gear adaptor 48 by o-ring 122. Further, air is prevented from leaking out of the coolant path and into the gear assembly 36 between the ring gear 44 and the motor casing 46 by o-ring 66, and is prevented from leaking out between the inner sleeve 116 and ring gear 44 by sealing engagement between the ring gear, elastomeric cover 68 and inner sleeve 116.

[0085] Since the air flow runs past the motor 34 between the sleeves 116, 118, as the air flow is directed past the motor it is prevented from contacting the motor. The inner sleeve 116 spaces the air flow apart from the motor 34, therefore the air flow does not absorb as much heat from the motor at this point as it would do if the inner sleeve was absent and the air flow could run over the motor. The air flow is therefore cooler when it reaches the gear assembly 36, and is thus more able to cool it. That being said, the inner sleeve 116 conducts heat away from the motor 34 and a significant proportion of this heat is absorbed by the air flow, therefore the air flow nonetheless has a cooling effect on the motor 34 as it is directed past it.

[0086] The outer sleeve 118 (along with the inflow and outflow chambers 90, 92 of the motor support 72) is positioned to as to prevent the air flow from contacting the agitator. In contrast, if the outer sleeve 118 was absent and tubular portion 24a of the agitator 24 formed a wall of the coolant flow path, it would be necessary to provide kinetic seals at each end of the tubular portion (e.g. one between the tubular portion 24a and the sealing member 76, and another between the tubular portion and the end of the inner sleeve 116 which supports the carrier 42). Such kinetic seals are generally relatively expensive, require relatively tight tolerances and wear out relatively quickly.

[0087] From the gaps 62 in the gear adaptor 48, the air flow runs into the casing 46 of the motor 34 through the breather holes 64, through the motor, out of the motor through the holes 86 and into the inside space 84 of the motor adaptor 74. As the air flow passes through the motor 34, it absorbs further heat from the motor, thereby providing an additional cooling effect thereto.

[0088] From the inside space 84 of the motor adaptor 74, the air flow runs through the aperture 88 in the motor adaptor, through the duct 115 of the sealing member 76 and into the outflow chamber 92 of the motor support 72. Leakage of air out of the coolant path between the motor adaptor 74 and sealing member 76 is prevented by engagement between the sealing member 76 and the inner sleeve 116 and by the o-ring 120.

[0089] The air in the outflow chamber 92 is then drawn through the aperture 101 into radially-extending arm 100 of the L-shaped channel 98 defined by the mounting member 78 and sealing member 82. The air then flows along the L-shaped channel 98, into the duct 104 which forms the outlet from the coolant path. The air flow then merges with dirt-entrained air flowing from the suction chamber 18, and exits the suction nozzle 6 through the outlet 12.

[0090] It is noteworthy that in this embodiment the air flow through the coolant path flows over the gear assembly 36 and then through the motor 34. This ensures that the gear assembly is cooled sufficiently. If instead the air flow passed through the motor 34 and then over the gear assembly 36 (which may appear to be preferable at first glance, so as to avoid wear particles from the gear assembly from being drawn into the motor), the air flow may be too hot by the time it reaches the gear assembly for the gear assembly to be cooled adequately.

[0091] It is also to be noted that in this embodiment the coolant path directs the air flow to enter the agitator 24 at one axial end (through the aperture 110 and the inflow chamber 90), and to exit the agitator at the same axial end (through the outflow chamber 92 and the aperture 101). This enables the opposite end of the agitator and the associated structure to be relatively simple in comparison to an arrangement where the coolant path was required to pass through this end of the agitator as well.

[0092] In this embodiment, the agitator 24 is removable from the suction nozzle 6. More particularly, it is removable from around the motor 34. This will be described in more detail below with reference to FIGS. 12 and 13, in combination with FIGS. 1-11. In this embodiment, the agitator 24 is removable through an aperture 136 in the casing 16 at an axial end of the agitator, which is selectively closable by an end cap 138. In this case, the end cap 138 provides end wall 16f, a sealing member 139, and a hair ingress flange 140 which projects into an end of the agitator in close radial clearance therewith so as to reduce the possibility of hair working its way further into the agitator 24.

[0093] The agitator is supported for its rotation on two bearings 142, 144. Bearing 142 is positioned in the hair ingress flange 140 of the end cap, and engages a stub 146 of the closed end part 24b of the agitator 24. Bearing 144 is positioned on the motor support 72, adjacent to another hair ingress flange 148, and engages the inside of the tubular part 24a of the agitator 24 via a support ring 150. The support ring 150 has a circumferential array of spaced-apart fins 152 which slidingly engage the tubular part 24a of the agitator. The fins 152 being spaced apart means that any pressure difference across the support ring 150 (for instance due to a temperature difference) can equalise. Otherwise, this pressure difference could pull dirt into the bearing 144 and clog it.

[0094] The end cap 138 has circumferential array of recesses 154, each recess being bounded by an outwardly-projecting ridge 156. The aperture 136 has a complementary circumferential array of projections in the form of lugs 158. The end cap 138 can be attached to the housing suction nozzle 6 by rotating the end cap about the longitudinal axis 26 of the agitator 24 to a locked position, which positions each lug 158 within a corresponding recess 154. In other words, the ridges 156 are hooked onto the lugs 158. The end cap 138 can be released from the suction nozzle 6 by rotating the end cap 138 to the unlocked position, which positions the lugs 158 outside of the recesses 154.

[0095] The end cap 138 has a pivotable latch member 160 which can secure the end cap in the locked position. This reduces the risk of the end cap 138 being rotated to the unlocked position (thereby potentially opening the aperture 136 and releasing the agitator 24) unintentionally, for instance due to a knock. The latch member 160 is pivotably mounted on the end cap 138, and has a latch tooth (not visible) and a push-button 162. The latch tooth (not visible) engages an abutment surface 164 provided on the lower housing 16b so as to prevent rotation of the end cap 138 to the unlocked position. Further, the latch tooth (not visible) can be lifted out of alignment with the abutment surface by pressing the button 162 and thereby pivoting the latch member 160.

[0096] The agitator 24 sildably engages the bearing 144 via the support ring 150 as noted above. However, the stub 146 of the agitator 24 and the bearing 142 exhibit an interference fit. Accordingly, when a user removes the end cap 138, the agitator is removed along with it. Nonetheless, the agitator 24 and end cap 138 are separable from one another by applying sufficient force to overcome the interference fit between the bearing 142 and the agitator 24.

[0097] It is noteworthy that in this embodiment the sealing members 76, 80, 82 and 124; o-rings 120, 122, 126; and cover 68 are all deformable, in this case being made of elastomeric material. This not only ensures that a full seal can be provided, but also the sealing members to provide additional functionality. These components being deformable means that slight misalignment between parts of the suction nozzle 6 can be accommodated without adversely affecting performance. Also, the deformability of these components can reduce the propagation of vibration between different parts of the suction nozzle, acting as dampers and thereby making the suction nozzle more stable and/or quieter.

[0098] It will be appreciated that numerous modifications to the above described embodiments may be made without departing from the scope of invention as defined in the appended claims. For instance, whilst in the above embodiment the air flow through the coolant path is directed past the motor and then through the motor, in other embodiments the air flow may be directed past the motor and then over the motor (for instance it may pass over the circumferential periphery of the casing of the motor). Similarly, in other embodiments the air flow may run through the gear assembly rather than over it.

[0099] In the above embodiment, the gap between the inner and outer sleeves forms a passage of continuous annular cross section. In other embodiments, however, the gap may form a passage of annular cross section which is made up of an annular array of individual passages (as would be the case, for instance, if the ridges of the inner sleeve of the embodiment above were extended so that they contacted the outer sleeve). Other embodiments may utilise inner and outer sleeves, but the sleeves may not define a passage of annular cross section. For example, the outer surface of the inner sleeve may contact the inner surface of the outer sleeve around most of its circumference, and be spaced therefrom at a single circumferential point so as to define a single passage of non-annular cross section.