GB2592572A

GB2592572A - Pole Sander

Info

Publication number: GB2592572A
Application number: GB2001278.7A
Authority: GB
Inventors: Zimmerman Dominic
Original assignee: Black and Decker Inc
Current assignee: Black and Decker Inc
Priority date: 2020-01-30
Filing date: 2020-01-30
Publication date: 2021-09-08
Also published as: GB202001278D0

Abstract

A handheld pole sander for sanding, polishing, grinding or rubbing a work surface has an elongate body (102 fig.2) and a sanding head 100 attached via a pivot mechanism (110 fig.4). An electric motor (114 fig.16) with an output spindle (118 fig.16) is mounted on the sander and is controlled by control electronics (144 fig.19). The elongate body includes first and second poles 196, 198 which can slide in and out of each other telescopically. The first pole 196 has a single aluminium tube with an internal wall 202 to form two passageways 148, 154 and the second pole 102 has a first tube 206 and a second tube 208 mounted in parallel to the first tube and inside it which may allow routing of cables and dust extraction.

Description

POLE SANDER

The present invention relates to a locking mechanism for a telescopic pole of a power tool, such as, a pole sander.

Pole sanders typically comprise a telescopic pole with a sanding head pivotally mounted on one end. The sanding head comprises a hood which surrounds a platen which is mounted on an output spindle which projects from the hood. Sand paper can be attached to the platen for sanding a work surface. Alternatively, a polishing pad can be attached to polish a work surface.

The output spindle and hence the platen, is rotated by an electric motor. The electric motor can be mounted on the sanding head. Alternatively, the motor can be mounted on the end of the telescopic pole remote from the sanding head. A vacuum cleaner can be attached to the sanding head, typically via a pipe which extends through the telescopic pole, to remove dust generated by the sanding action of the rotating platen from under the hood.

Examples of pole sanders are disclosed in EP0727281, EP2033738, DE102014103019, W02014/086873, EP3083139 and DE102014112355.

Figure 28 discloses a prior art design of locking mechanism 200 for a telescopic pole of a pole sander. The telescopic pole comprises a first pole which slides in and out of a second pole to enable the length of the pole sander to be adjusted, the first pole locating inside of the second pole when the telescopic pole is adjusted to its shortest length.

The locking mechanism comprises a sleeve 600 which has a first section 602 and a second section 604. The first section 602 is used to attach the locking mechanism 200 onto the second pole of the pole sander. The second section 604 forms a clamp which can be releasably tightened around the first pole in order to releasably axially lock the first pole to the second pole.

The first section 602 comprises a resiliently deformable first C shaped sleeve 606 with two parallel flaps 612 extending from the edges of the first C shaped sleeve 606. A gap (indicated by Arrow 608) is formed between the two flaps 612. When no external forces are applied to the first C shaped sleeve 606, the first C shaped sleeve 606 is held in a pre-set shape with a pre-set cross-sectional area with the width of the gap 608 between the flaps 612 being held at a pre-set distance by the resilient nature of the first C shaped sleeve 606. The first C shaped sleeve 606 can be deformed using a bolt 610 which passes through the flaps 612 in such a manner that the width of the gap 608 can be decreased from the pre-set width, reducing the size of the pre-set cross-sectional area of the first C shaped sleeve. When no force is applied by the bolt 610, the first C shaped sleeve 606 reverts to the pre-set shape with the width of the gap 608 reverting to the pre-set distance.

Formed through each flap 612 is a hole (not shown). The diameter of the hole is slightly larger than that of the shaft (not shown) of the bolt 610 but less than the head 614 of the bolt 610.

The shaft of the bolt 610 is inserted through one hole in one flap 612 and through the other hole in the second flap 612. A nut (not shown) is then threaded onto the free end of the shaft of the bolt 610. As the nut is screwed onto the shaft of the bolt 610, the two flaps 612, which are sandwiched between the head of the bolt 610 and the nut, move towards each other as the nut is screwed onto the shaft reducing the width of the gap 608.

Formed in each side of the first C shaped sleeve is an elongate slot 616 which extend from the edges of the first C shaped sleeve 606 up the sides of first C shaped sleeve 606 to a second hole 618. The elongate slots 616 and second holes 618 are capable of engaging ridges and/or pegs (not shown) on the second pole of the pole sander.

The locking mechanism 200 is attached to the second pole of the pole sander as follows. The first pole is separated from the second pole. The nut is unscrewed from the bolt 610 (whilst the shaft of the bolt 610 remains in the two holes of the faps 612) to allow the first C shaped sleeve 606 of the first section 602 to revert to its pre-set shape with the width of the gap 608 between the flaps 612 reverting to the pre-set distance. The first C shaped sleeve 606 of the first section 602 is then slid onto the end of the second pole, with the elongate slots 616 and second holes 618 aligning with ridges and pegs formed on the outer surface of the second pole. The nut is then screwed onto the shaft of the bolt 610, the two flaps 612 which are sandwiched between the head 614 of the bolt 610 and the nut, being moved towards each other, reducing the width of the gap 608 and the size of the cross-sectional area of the second C shaped sleeve. This results in the elongate slots 616 and second holes 618 engaging with and holding onto the ridges and pegs formed on the outer surface of the second pole in addition to the first C shaped sleeve engaging with and holding the outer surface of the end of the second pole as the cross-sectional area is reduced. The nut is tightened until the first C shaped sleeve 606 is firmly secured to the second pole. The first pole is then inserted through the second section 604 of the locking mechanism 200 and into the second pole. The clamp of the second section 604 is then used to lock onto the first pole to secure the first pole within the second pole.

The second section 604 is described with reference to Figures 28 and 29. The second section 604 comprises a resiliently deformable second C shaped sleeve 630 with two parallel flaps 632 extending from the edges of the second C shaped sleeve 630. A gap (indicated by Arrow 634) is formed between the two flaps 632. When no external forces are applied to the second C shaped sleeve 630, the second C shaped sleeve 630 is held in a pre-set shape with a pre-set cross-sectional area with the width of the gap 634 between the flaps 632 being held at a preset distance by the resilient nature of the second C shaped sleeve 630. The second C shaped sleeve 630 can be deformed using a bolt 636, which passes through the flaps 632, and a cam 638 attached to the bolt 636 in such a manner that the width of the gap 634 can be decreased from the pre-set width. When no force is applied by the bolt 636 and cam 638, the second C shaped sleeve 630 reverts to the pre-set shape with the width of the gap 634 reverting to the pre-set distance.

Formed through each flap 632 is a hole (not shown). The diameter of the hole is slightly larger than that of the shaft 640 of the bolt 636 but less than the head 642 of the bolt 636. The shaft 640 of the bolt 636 is inserted through one hole in one flap 632 and through the other hole of the second flap 632. A nut 644 is then threaded onto the free end of the shaft 640 of the bolt 636. The nut 644 is screwed onto the shaft 640 of the bolt 636 until the two flaps 632 are sandwiched between the head 642 of the bolt 636 and the nut 644 and the flaps 632 have been moved to a second pre-set distance from each other, the two flaps 632 being held against the head of the bolt 636 and the nut 644 by the resilient nature of the second C shaped sleeve 630 urging the flaps 632 apart.

The cam 638 is pivotally mounted on a rod 646 which passes though the head 642 of the bolt 636. The cam 638 can pivot about an axis, which extends longitudinally along the length of the rod 646, perpendicularly to the longitudinal axis of the shaft 640 of the bolt 636. An edge 648 of the cam 638 abuts against the side of one of the flaps 632. The cam 638 is circular in shape with the rod 646 locating eccentrically relative to the centre of the circular cam 638. As such, as the cam 638 is rotated, the distance of the edge 648 of the cam 638, which abuts against the side wall of the flap 632, from the rod 646 changes dependent on the angular position of the cam 638 relative to the flap 632. The side wall of the flap 632 remains in contact with the edge 648 of the cam 638 due to the resilient nature of the second C shape sleeve 630 which biases the two flaps 632 away from each other with one of the flaps 632 being biased into engagement with the edge 648 of the cam 638. Attached to one side of the cam 638 is an arm 658 which is curved along its length. The arm 658 is used by an operator to rotate the cam 638 in order to move the flap 632 abutting against the edge 648 of the cam 638, altering the size of the gap between the two flaps 632 between a large gap and a small gap, the flaps 632 being moved due to the resilient nature of the second C shaped sleeve 630. A groove 650 is formed around the second section 604. The curve of the arm 658 is the same as the curve of the base of the groove 650. When the arm 658 is pivoted so that it is perpendicular to the base of the groove 650, the size of the gap between the flaps 632 is the greatest (when the position of the nut 644 on the shaft 640 of the bolt 636 remains fixed). When the arm 658 is pivoted so that it is locates within the groove 650 so that the arm 658 is flush with the base of the groove 650 (whilst the position of the nut 644 on the shaft 640 of the bolt 636 remains fixed), the size of the gap between the flaps 632 is the smallest.

The operation of the clamping mechanism of the second section 604 will now be described. The locking mechanism is attached to the end of the second pole as described above. The arm 658 of the second section 604 is then pivoted so that it is perpendicular to the base of the groove 650 so that the size of the gap between the flaps 632 is the greatest. This results in the largest cross -sectional area of the second C shaped sleeve 630 which is greater than the cross-section area of the first pole. The first pole is then inserted through second C shaped sleeve 630 of the second section 604 of the locking mechanism 200 and into the second pole. The arm 658 is then pivoted so that it is located in the groove 650 flush with the base of the groove 650 so that the size of the gap between the flaps 632 is the smallest. This results in the smallest cross -sectional area of the second C shaped sleeve 630 which is slightly smaller than the cross-section area of the first pole. As such, the second C shaped sleeve 630 engages with and holds the outer surface of the first pole as the cross-sectional area is reduced. This locks the first pole to the locking mechanism which in turn is attached to the second pole.

Accordingly, there is provided a handheld pole sander in accordance with claim 1.

Figure 1 shows a top view of the pole sander; Figure 2 shows a side view of the pole sander; Figure 3 shows a vertical cross-sectional view of the pole sander; Figure 4 shows a perspective view of the sanding head; Figure 5 shows an underside view of the sanding head with the platen removed; Figure 6A shows a vertical cross-sectional view of the edge of the sanding head; Figure 6B is the same as Figure 6A with the addition of hatching to show cross sectional area of gap between edge of the platen and the inner wall; Figure 7 shows a perspective view of the brush ring; Figure 8 shows a view of part of the top side of the plate with the leaf spring of the brush ring 132 passing through an aperture from below the plate to attach to the top side of the plate; Figure 9 shows a schematic diagram showing how the two poles of the elongate body are telescopically connected to each other; Figure 10 shows the seals which connect between the two poles of the elongate body; Figure 11A shows the seal for the first pole 196 being attached to the first pole 196; Figure 118 shows a vertical cross section of the seal for the first pole 196 being attached to the first pole 196; Figure 11C shows the seal for the first pole 196 mounted on the first pole 196; Figure 12 shows the seals adjacent the ends of the aluminium tubes of the poles; Figure 13 shows a perspective cross section showing how the aluminium tubes and seals of the two poles of the elongate body are telescopically connected to each other; Figure 14 shows a perspective cross section showing how the aluminium tubes and seals of the two poles of the elongate body are telescopically connected to each other; Figure 15 shows a top view of the sanding head; Figure 16 shows a vertical cross section of the sanding head and lower end of the first pole 196; Figure 17 shows the underside view of the sanding head including the platen; Figure 18 shows the platen; Figure 19 shows the rear housing with one of the clam shells removed; Figure 20 shows a vertical cross section of the rear housing; Figure 21 shows a top perspective view of the sanding head; Figure 22 shows the extension tube inside the handle section of the rear housing with the vacuum nozzle detached; Figure 23 shows the extension tube inside of the handle section of the rear housing with the vacuum nozzle attached; Figure 24 shows the rear end of the extension tube with the vacuum nozzle detached; Figure 25 shows the rear end of the extension tube with the vacuum nozzle attached; Figure 264 and Figure 26B show a first angle of the tubular passageway of the hood; Figure 274 and Figure 27B shows a second angle of the tubular passageway; Figure 28 shows a prior art of locking mechanism for a telescopic pole of a pole sander; Figure 29 shows a sketch of a cross section of the prior art locking mechanism in the direction of Arrows M shown in Figure 28; Figure 30 shows a locking mechanism according to the present invention mounted on the elongate body of a pole sander; Figure 31 shows an exploded view of the first and second poles of the elongate body together with the locking mechanism as shown in Figure 30; and Figure 32 shows a cross sectional view of the locking mechanism mounted on the elongate body of a pole sander shown in Figure 30.

Referring to Figures 1 to 3, the pole sander comprises a sanding head 100 pivotally attached to one end of an elongate body 102 and a rear housing 104 attached to the other end.

The elongate body 102 is telescopic and is formed from two poles 196, 198, one of which slides in an out of the other as described in more detail below.

The sanding head 100 connects to the end of the elongate body 102 via a pivot mechanism 110 which is described in more detail below. The sanding head 100 comprises a hood 112 on top of which is mounted an electric motor 114. The motor 114 is a DC brushless motor 114.

The motor 114 is enclosed by a motor housing 120 which is cup shaped and surrounds the top and sides of the motor 114. The motor housing 120 attaches to the top of a gear housing 122 which encloses a planetary gear set 124. The gear housing 122 mounts on top of the hood 112. The motor 114 is drivingly connected via the planetary gear set 124 to an output spindle 118 having a longitudinal axis 126 about which it rotates and which is located below the hood 112. Attached to the end of output spindle 118 is a circular platen 116 which extends radially outwards from the output spindle 118. When the motor 114 is activated, the motor 114 rotationally drives the output spindle 118 and hence the platen 116 about a drive axis 126.

A flexible dust extraction pipe 128 attaches to the top of the hood 112 on one side of the motor 114. An aperture 130 is formed through the hood 112. The end of the flexible pipe 128 surrounds the aperture 130. As such air can be drawn from beneath hood 112 through the aperture 130 and into the flexible pipe 128. This enables dust and debris generated during the operation of the pole sander to be removed from under the hood 112 by applying a suction force to the flexible pipe 128. The operation of the dust extraction of the pole sander is described in more detail below.

A brush ring 132 attaches to the edge of the hood 112. The brush ring 132 is described in more detail below.

The rear housing 104 is formed two plastic clam shells 134 which clamp to the end of the elongate body 102. The rear housing 104 comprises a forward mount section 136 and rear handle section 138. A battery mount 140 is formed on the lower surface of the mount section of the rear housing 104. A battery pack 142 can be slid in a forward direction (Arrow M in Figure 19) onto the battery mount 140 to attach it to the rear housing 104 and in a rearward direction to detach it from the battery mount 140. The design of the battery mount 140 and battery 142 are known in art and therefore will not be described in any more detail.

Control electronics 144 for the motor 114 are mounted inside of forward mount 136 section of the rear housing 104. The control electronics 144 are connected to the motor 114 via an electric cable 146 which passes through a second passageway 148 of the elongate body 102 through the length of the elongate body 102. The control electronics 144 control the operation of the brushless motor 114.

A lock on/lock off switch 150 is mounted on the top of rear housing 104 where the rear handle section 138 connects to the forward mount section 136. An operator can use the lock on/lock off switch 150 to activate the motor 114.

An operator can support the pole sander by grasping the rear handle section 138 of the rear housing 104 in one hand and the elongate body 102 in the other. The operator can switch the pole sander on or off using the thumb of the hand grasping the rear handle section 138.

A vacuum connection nozzle 152 is mounted on the rear of the rear housing 104 which connects to a first passageway 154 which extends through the length of the elongate body 102. The other end of the second passage 154 connects to the flexible pipe 128. A vacuum cleaner (not shown) can be connected to the nozzle 152 and draw air from under the hood 112, through the flexible pipe 128, through the first passage 154 in the elongate body 102, through the nozzle 152 and into a vacuum cleaner.

The hood 112 will now be described with reference to Figures 4 to 6.

The hood 112 comprises a circular plate 156 which extends radially from a central circular hole 158 through which the output spindle 118 projects. Formed on the underside of the plate 156 around the edge is a peripheral wall 160 which projects perpendicularly to the plane of the circular plate 156. An inner circular inner wall 162 is formed on the underside of the plate 156 in close proximity to and concentrically with the peripheral wall 160. The inner wall 162 has the same height as the peripheral wall 160 and extends in the same direction that is parallel to the peripheral wall 160. A circular trough 164 is formed between the two walls 160, 162. Six rectangular apertures 166 are formed through the base of the trough 164. The apertures 166 are located equidistantly around the centre of the plate 156 in a symmetrical fashion. A chamber 166 is formed between the inner wall 162 and the underside of the plate 156.

Formed through the plate 156 between the inner wall 162 and the central hole is an arc shaped aperture 130 which allows air and debris to pass through the plate 156. The aperture 130 has three edges, a first straight edge 170 which extends tangentially to the longitudinal axis 126 of the output spindle 118, a second edge 172 of equal length which extends from the end of the first edge 170, perpendicularly to the first edge 170, in a direction away from the longitudinal axis 126 of the output spindle 118, and a third curved edge 174 extending between the ends of the first and second edges 170, 172. The circular plate 156 has a radius R. The whole of the arc shaped aperture 130 is located at a distance of less than half of the radius from longitudinal axis 126 of the output spindle 118 or the centre of the plate 156 (<8/2).

Integrally formed on the top side of the plate 156 is a curved wall 178 which forms a tubular passageway 176 from the arc shaped aperture 168 to an opening where the flexible pipe 128 is attached. Where the tubular passageway 176 connects to the arc shaped aperture 130, it is shaped to engage with the arc shaped aperture 130 at certain angles to maximise the air flow efficiency.

Referring to Figures 26A and 268, the first angle of the exit of the tubular passageway 176 is located in a vertical plane 300 which passes through axis of rotation 126 of the output spindle 118 across the end of the tubular passage 176 adjacent the arc shaped aperture 168. The angle 302 in this plane 300 between the axis of rotation 126 of the output spindle 128 and the direction of the tubular passageway 176 is less than 90 degrees (perpendicular) but greater than 0 degrees (parallel) and is ideally between 20 degrees and 60 degrees.

Referring to Figures 27A and 278, the second angle of the exit of the tubular passageway 176 is located in a vertical plane 304 which extends tangentially to the axis of rotation 126 of the output spindle 128, the part of the plane 304 which passes through the exit of the tubular passageway 176 being the closest part to the axis of rotation 126 of the output spindle 118.

The angle 308 in this plane 304 between the plane of the circular plate 156 of the hood 112 and the direction of the tubular passage 176 in the turning direction 306 of the platen 116 is less than 90 degrees and is ideally between 20 degrees and 60 degrees.

The hood 112 is formed in a one-piece construction from plastic.

The brush ring 132 will now be described with reference to 6 to 8.

The brush ring 132 comprises a plastic circular ring 180 which is sized so that it is capable of locating inside of the trough 164. Extending perpendicularly from the bottom side of the ring 180 are a series of bristles 182. Attached to the opposite top side of the brush ring 132 are the ends 184 of six leaf springs 186. The leaf springs 186 are formed from sheet metal and are resiliently deformable in a direction perpendicular to the plane of the sheet. The leaf springs 186 comprises a central section 188 located between two end sections 184, 190. The end sections 184, 190 extend in a direction parallel to the top surface of the ring 180. The central section 188 of the leaf springs 186 extends upwardly at a slight angle to the plane of the circular ring 180. Each central section 188 of each leaf spring 186 extends through the rectangular aperture 166 in the trough 164 and attaches to the top side 194 of the plate 156 as shown in Figure 8. The leaf springs 186 bias the ring 180 to a position where it is located at a distance from the base of the trough 164 as shown in Figure 6. In this position, the bristles 182 project below the hood 112. When the sanding head 100 is placed against a work surface, the bristles 182 engage with the work surface. When the sanding head 100 is pushed against the work surface, the brush ring 132 is pushed into the trough 164 against the biasing force of the leaf springs 186. The leaf springs 186 ensure that the bristles 182 are biased into engagement with the work surface. When the sanding head 100 is removed from the surface, the brush ring 132 returns to its original position due to the resilient nature of the leaf springs 186.

A plastic cover 195 is located over the topside of the hood 112 enclosing the ends 190 of the leaf springs 186 attached to the top side 194.

The telescopic elongate body 102 will now be described with reference to Figures 1 to 3 and 9 to 14.

The pole sander has an elongate body 102 comprising a first pole 196 which is capable of sliding in and out of a second pole 198 in a telescopic manner to enable the length of the pole sander to be adjusted. A locking mechanism 200 is used to lock the first pole 196 to the second pole 198 when the two poles 196, 198 have been telescoped to a preferred length.

Inside both of the poles 196, 198 are two passageways 148, 154 which run the length of the both poles 196, 198. The first larger passageway 154 is used to transport air (due to suction) and entrained dust and debris, generated during the use of the pole sander, through the poles 196, 198 from the working end to a vacuum nozzle 152 at the opposite end, the nozzle 152 being connected to a vacuum cleaner. The second smaller passageway 148 is used as a conduit for electric cable 146 which provide power and control signals from a control electronics 144 for the electric motor 114 mounted in the sanding head 100.

The first pole 196 comprises a single aluminium tube with an internal wall 202 located inside of the tube, which runs the length of the tube to form the two passageways 148, 154 which run the length of the first pole 196. The first larger passageway 154 forms part of the first passageway which is used to transport air. The second smaller passageway 148 forms part of the passageway which is used as a conduit for the electric cable 146. A first seal 204 attaches to the end of the first pole 196 which is inserted into the second pole 198. The shape of the seal 204 corresponds to that of the end of the aluminium tube and internal wall 202. The first seal 204 provides a seal between the first pole 196 and the second pole 198. It also acts as a slide bearing.

The second pole 198 comprises two aluminium tubes 206, 208. The second aluminium tube 208 locates inside of the first aluminium tube 206 and runs the full length of the first tube 206, their longitudinal axes being parallel to each other. The second aluminium tube 208 forms part of the first passageway which is used to transport air and dust or debris. The first aluminium tube 206 forms part of the passageway 154 which is used as a conduit. A second seal 210 is attached to the end of the first aluminium tube 206 into which the first pole 196 is inserted. The shape of the second seal 210 corresponds to that of the end of the aluminium tube 206. A third seal 212 is attached to the end of the second aluminium tube 208 which is inserted into the second passage 148 way of the first pole 196. The shape of the third seal 212 corresponds to that of the end of the second aluminium tube 208. The seals 210,212 provides a seal between the first pole 196 and the second pole 198. They also act as slide bearings. The two tubes 206, 208 are connected to each other at their ends remote from the seals 210, 212 so that relative movement between the two tubes 206, 208 is prevented.

The poles 196, 198 are assembled as following. The end with the third seal 212 of the second aluminium tube 208 of the second pole 198 is inserted into the second passageway 148 of the first pole 196 through the seal 212. The end of the first pole 196 with the first seal 204, with the second aluminium tube 208 inside of it, is then inserted into the end of the first aluminium tube 206 of the second pole 198 with the second seal 212.

The poles 196, 198 can be telescopically locked using the locking mechanism 200 described below.

The larger passageway 154 in the first pole 196 connects directly to an end of the flexible tube via a collar 214. The larger passageway 154 in the second pole 198 connects to an end of the vacuum attachment nozzle 152 via an extension tube 216.

As the poles 196, 198 are made from aluminium, they are conductive. As such the poles, 196, 198 are electrically grounded by being electrically connected to neutral in the electronic control electronics 144 in the rear housing 104. in order to ensure that the whole of elongate body 102 is grounded, ideally, the seals 204, 210, 212 are manufactured from electrically conductive material. This ensures a good electrical connection between the two poles 196, 198.

In addition or as an alternative, metal contacts 218 such as leaf springs, at least one electric cable and/or an electrical connector can be connected between the telescopic poles 196, 198 I to ensure electrical conductivity between the poles 196, 198. Ideally, they are located between the overlapping parts of the telescopic poles 196, 198.

Referring to Figures 30 to 32, the locking mechanism 200 for locking the first pole 196 to the second pole 198 according to the present invention will now described.

The locking mechanism comprises a sleeve 600 which has a first section 602 and a second section 604. The first section 602 is used to attach the locking mechanism 200 onto the second pole of the pole sander. The second section 604 forms a clamp to releasably axially lock the first pole to the second pole. The second section 604 is the same as that of the prior art design described above with reference to Figures 28 and 29 in relation to the prior art design. The first section 602 is connected at a top half to the second section 604 by a bridge 660 but is separated at a bottom half by an elongate gap 662.

The design of the first section 602 is new and forms an embodiment of the invention as covered by the claims.

The cross-sectional shape of the aluminium tube the first pole 196 is oval. The cross-sectional shape of first aluminium tube 206 of the second pole 198is also oval.

The first section 602 comprises a tubular sheaf 670 which has an oval shape in cross-section and which is capable of sliding over the end of the first aluminium tube 206 of the second pole 198. A rectangular cut out 672 is formed through one side of the sheaf 670 which forms an aperture through the side of the sheaf 670. The cut out 672 is rectangular in shape, with the longer edges 674 of the rectangular cut out 672 extending in a direction parallel to a longitudinal axis 676 of the sheaf 670. A resilient planar rectangular tab 678 is connected at one of its ends to a shorter edge 680 of the cut out 672, the tab 678 extending across the cut out 672 in a direction parallel to the plane of the cut out 672 and, in its lengthwise direction, parallel to the longer edges 674 of the cut out 672. The resilient tab 678 is connected at one end to the shorter edge 680 of the cut out 672 which is located closest to the section 604. The free end of tab 678 can flex in a direction perpendicular to the plane of the cut out 672. The ratio of the dimensions of the shorter sides of the tab 678 to the longer sides of the tab 678 is the same as that of the ratio of the dimensions of the shorter edges 680 of the cut out 672 to the longer sides 674 of the cut out 672. The size of the sides of the tab 678 are slightly smaller than those of the cut out 672 leaving a gap between the longer sides of the tab 678 and the longer edges 676 of the cut out 672 and between the free end of the tab 678 and the short edge 680 of the cut out 672 adjacent the free end.

The thickness Ti of the tab 678, as best seen in Figure 32 is less than half of the thickness T2 of the sheaf 670. The base 684 of the tab 678 is co-planer (flush) with that of the inner wall 686 of the sheaf 670. A catch 682 is formed on the tab 678 adjacent the free end of the tab 678. The catch 682 extends in a direction perpendicular to the plane of the tab 678 away from the base 684 into the space formed within the cut out 678. The catch 682 comprises a forward facing tapered edge 688 which starts at a forward edge of a ridge 689 formed on the end of the catch 682 and which is orientated so that it extends in a direction away from the second section 604. The catch 682 also comprises a smaller rearward facing tapered edge 690 which starts at a rearward edge of the ridge 689 and which is orientated so that it extends in a direction towards from the second section 604.

The diameter of the first aluminium tube 206 is greater than that of the inner wall 686 of the sheaf 670. Therefore, the inner wall of the front end of the sheaf 670 has been cut away to provide a slot 692 into which the front end of the first aluminium tube 206 of the second pole 198 can be slid. The tab 678 has a diameter relative to the axis 676 of the sheaf 670 that is smaller than that of the aluminium tube 206 (the outer diameter of the tab 678 relative to the axis 676 of the sheaf 670 being the same as the inner diameter of the aluminium tube 206) so that the tab 670 locates inside of the aluminium tube 206 when the sheaf 670 is mounted on the end of the aluminium tube 206 (with the outer surface of the tab 678 located against the inner surface of the aluminium tube 206 as shown in Figure 32).

The front end of the first aluminium tube 206 of the second pole 198 comprises a series of windows 694 which are located adjacent the front edge of the first aluminium tube 206 of the second pole 198 equidistantly around the circumference of the end of the first aluminium tube 206. The windows 694 are of a suitable size so that, when the sheaf 670 is mounted on the front end of the aluminium tube 206, each window 694 can receive the catch 682, the catch 682 being able to pass through each window 694 when aligned with it. The windows 694 are located rearward from the front edge of the aluminium tube 206 such that, when the catch 682 is located in a window 694, the front edge locates within the slot adjacent the rear edge of the cut out 672.

The locking mechanism 200 is attached to the first aluminium tube 206 of the second pole 198 as follows.

The front end of the first aluminium tube 206 of the second pole 198 is slid into the front end of the sheaf 670 by the front edge 673 of the font end entering into and sliding rearwardly along the slot 692 of the front end of the sheaf 670. As the front end slides further into the slot, the front edge engages with the forward facing taper 688 of the catch 682. Continued movement of the front edge 673 causes the tab 678 to bend inwardly towards the axis 676 of the sheaf 670 due to the shape of the front taper 688 as it pushes the catch 682 out of the way. As the front end of the aluminium tube 206 continues to enter the sheaf 670, the end of the catch 682, which has been pushed inwardly out of the way, engages with and slides along the inside wall of the aluminium tube 206with the tab 670 locating inside of the aluminium tube 206. The aluminium tube 206 continues to enter the sheaf 670 until the catch 682 aligns with a window 694 on the inside of the aluminium tube 206 (this may require some rotation of the aluminium tube within the sheaf 670). When the catch 682 aligns with the window 694, it moves outwardly to enter the window 694 due to the resilient nature of the tab 678 which reverts back to its original shape. When the catch 682 is located inside of the window 694, it is held in place by the resilience of the tab 678 which seeks to maintain its original shape.

When the catch 682 is located inside of the window 694, the base 684 of the tab 678 aligns with the inner wall of the sheaf 670 so that they are flush with each other with the outer surface of the tab 678 located against the inner surface of the aluminium tube 206 as shown in Figure 32.

After the sheaf 670 is mounted on the end of the aluminium tube with the catch 682 located within a window 694, the aluminium tube of the first pole 196 is inserted into the second section 604 of the sleeve 600 and then into the end of the first aluminium pole 206 of the second pole 198. When the aluminium tube of the first pole 196 has been inserted in to the end of the second pole 198, it is surrounded by the first aluminium tube 206 of the second pole 198, which in turn is surrounded by the sheaf 670. The aluminium tube 206 of the first pole 196 locates against the base 684 of the tab 678, preventing it from moving perpendicularly to the plane of the cut out 672 as best seen in Figure 32. As such, the tab 678 is held sandwiched between the aluminium tube of the first pole 196 and the first aluminium tube 206 of the second pole 198. As such, the catch 682 is prevented from leaving the window 694 in the first aluminium tube 206. Therefore, when the first pole 196 is inserted into the second pole 198, the sheaf 670 is locked onto the second pole 198. The position of the first pole 196 can then be locked relative to the second pole 198 using the clamping mechanism in the second section 604.

In order to remove the sheaf 670 from the first aluminium tube 206 of the second pole 198, the clamping mechanism of the second section 604 is released and the first pole 196 is first removed from the first aluminium tube 206 of the second pole 198. The catch 682 is then pushed inwardly, moving it out of the window 694 into the first aluminium tube 206. The sheaf 670 can then be slid off the end of the first aluminium tube 206 of the second pole 198, the catch 682 sliding along the inside wall of the first aluminium tube 206 of the second pole 198 as it does so until it disengages with the second pole 198.

It will be appreciated that the second aluminium tube 208 of the second pole 198 remains located inside of the first aluminium tube 206 of the second pole 198 during the procedure of attaching and using the locking mechanism 200 on the first and second poles 198.

Whilst the sheaf 670 described above completely surrounds the end of the first aluminium tube 206 of the second pole 198, it will be appreciated that the sheaf 670 can partly surround the tube 206, the sheaf 670 extending in a circumferential direction around the first aluminium tube 206 sufficiently to enable the sheaf 670 to slide on an off the end of the first aluminium tube 206 in an axial direction but prevent the sheaf 670 from being removed from the first aluminium tube 206 in another direction e.g perpendicular to the axis 676 of the first aluminium tube 206.

Whilst in the embodiment, the cross sectional shapes of the aluminium tube the first pole 196 and the cross-sectional shape of first aluminium tube 206 206 of the second pole 198 are oval, it will be appreciated that the shape of cross sections could be over shapes such as round, square, rectangular triangular etc. whilst the design of the first section 602 could still function in the same manner.

The pivot mechanism 110 will not be described with reference to Figures 4, 15 and 16.

Attached to the end of the first pole 196 in a fixed manner is an end housing 220 (see Figures land 2) comprising two clam shells 222 attached to each other using screws (only one clam shell is shown in Figure 4). The pivot mechanism 110 connects the sanding head 100 to the first pole 196 via the end housing 220.

The pivot mechanism 110 comprises a fork 224 having two arms 226, a central interconnecting section 228 and a pole support section 230. The two arms 226 extend in parallel in a forward direction from the ends of the central interconnecting section 228 in a symmetrical manner. The pole support section 230 connects to the centre of the interconnection section 228 on the opposite side of the two arms 226 and projects in a rearward direction opposite but parallel to that of the two arms 226.

Formed in each side of the gear housing 122 in a symmetrical manner are threaded apertures. The axis 232 of the of the apertures are aligned with each other and are horizontal. Formed in the ends of the two arms 226 are apertures. When the fork 224 is attached to the sanding head 100, the ends of the two arms 226 align with the apertures formed in the gear housing. A bolt 234 is passed through each aperture in the end of the each arm 226 and screw into the threaded aperture in the side of the gear housing 122 to attach the fork 224 in a pivotal manner. The fork 224 can pivot around the bolts 234 about a horizontal sideways axis 232.

Rigidly mounted in a recess formed in the end of the pole support section 228 is the rear half of an axle 234. The axle 234 projects rearwardly. Formed in the end housing 220 is an elongate recess 236. The recess 236 extends in a direction parallel to the longitudinal axis of the first pole 196. The forward half of the axle 234 is mounted inside of the recess 236 via two bearings 240 supported by the end housing in the side walls of the recess. The bearings 240 allow the axle to rotate within the recess. The axle can rotate about an axis which is parallel to the longitudinal axis of the first pole 196 and which passes through the length of the second smaller passage 148 of the elongate body 102. This allows the fork 224, together with sanding head 100, to pivot about an axis which is parallel to the longitudinal axis of the first pole 196 and which passes through the length of the second smaller passage 148 of the elongate body 102. The axis also crosses the output axis 126 of the drive spindle.

The sanding head 100 has a centre of gravity 242. As best seen in Figure 15, the axis of pivot 232 of the fork 224 on the sanding head 100 is located forward (distance Din Figure 15) of the centre of gravity 242. Furthermore, the axis of pivot 232 of the fork 224 on the sanding head 100 100 is located forward of the drive axis 126 of the output spindle 118. This allows the sanding head 100, which can freely rotate about the bolts 234, to automatically pivot to an angular position where it is parallel to a wall when the sanding head 100 is raised by an operator.

When the plane of the platen 116 is parallel to the longitudinal axis of the elongate body 102 as shown in Figure 16, the axis of rotation of the axle is located below the centre of gravity 242 of the of the sanding head 100.

The design of the platen 116 will now be described with reference to Figures 17 and 18.

The platen 116 comprises a plastic disc 244 with a metal insert 246 located at the centre. Attached to the bottom of disk is layer made of a soft foam 248. Attached on the opposite side of the soft foam layer is a sheet of Velcro 250. The Velcro 250 is used to attach the sandpaper to the platen 116.

The platen 116 is attached to the output spindle 118 using a bolt 252. The platen 116 is circular and extends radially from the drive axis 126 in a direction perpendicular to the drive axis 126.

Two sets of air holes 254, 256 are formed through the platen 116 to allow air and debris to pass through the platen 116. The first set 254 are located towards the outer edge of the platen and in a symmetrical manner around the axis 126. The holes 254 of the first set are tear shaped with the narrower end pointing towards the centre. The straight sides of the holes 254 align with the centre of the platen 116. The second set of hole 256 are located between the first set 254 and the centre of the platen 116 in a symmetrical manner. The holes 256 of the second set are smaller than those of the first set. The holes 256 of the second set are tear shaped with the narrower end pointing towards the centre. The straight sides of the holes 256 align with the centre of the plate 116.

Referring to Figure 6A, a space 258 is formed between the top of the platen 116 and the underside of the hood 112. In the present design, the size H of the space is kept to a minimum. This ensures that the air speed above the platen 116 is kept as high as possible. If the air speed slows, entrained dust and debris will deposit on the surface of the underside of the hood 112 and therefore will build up. By keeping the air speed high, the dust remains entrained and therefore can be drawn out the flexible pipe 128 due to the suction from a vacuum cleaner.

The air flow around the rotating platen 116 is improved due to the inner circular inner wall 162 which is adjacent the outer edge of the platen 116. The inner wall 162 locates between the edge of the paten and the bristles 182 of the brush ring 132. The inner wall 162 guides the moving air in a smooth manner and minimises the amount of contact between the moving air and the bristles 182 of the brush ring 132. If the moving air were to come into contact with the bristles 182, the air flow would become non-uniform as its passes through the bristles 182. Furthermore, the use of the inner wall 162 to separate the bristles 182 from the edge of the platen 116 minimises the amount of dust and debris that collects within the bristles 182.

The cross-sectional area of the gap 260 between the inner wall 162 and the edge of the platen 116 (shown by the hatchings 262 in Figure 6B) is the same as that of the cross-sectional area of the flexible pipe 128 which in turn is the same as that of the first passageway 154 way in the two poles 196, 198.

Referring to Figure 19, the second pole 198 extends into the mount section 136 of the rear housing 104. A part 270 of the side wall first aluminium tube 206 of the second pole 198 has been removed to expose the surface of the second aluminium tube 208. The control electronics 144 are mounted in a control module. Where the part 270 of the first aluminium tube has been removed, the control module 144 is mounted inside of the first aluminium tube 206 adjacent the second aluminium tube 208. This enables heat generated by the electronic module 144 to be transferred to the second aluminium tube 208 which is a good heat conductor and transfer the heat away from the control module 144. Furthermore, during the operation of the pole sander, air is drawn through the second aluminium tube 208 by a vacuum cleaner. The air flow acts to cool the second aluminium tube 208 which in turn acts to cool the electronic module 144.

The control electronics 144 are connected directly to the motor 114 using a single electrical cable 146 which carries the wires use to provide the electrical current to the windings of the brushless motor 114. One end of the cable 146 connects directly to the control electronics 144 via a soldering tag 272 which connects to electric interface 274. The other end connects directly to the motor 114. The cable 146 is continuous with no plugs or connectors being used so as avoid interfering with the signals generated by the control electronics 144 which are sent down the cable 146 to operate the motor 114. A central section 276 of the cable 146 located inside of the two poles 196, 198 is helical to enable the length of the cable 146 in a direction parallel to the longitudinal axis of the poles 196, 198 to extend or reduce depending on the relative telescopic positions of the two poles 196, 198. When the cable 146 exit the first pole 196 and pass across the pivot mechanism 110, it locates against the side of flexible pipe 128 as shown in Figure 21.1n order to maintain the position of the cable 146 relative to the flexible pipe 128, a tubular sheaf 278 surrounds both the cable 146 and the flexible pipe 128 as shown in Figures 26 and 27.

An extension tube 280 connects to the end of the second aluminium tube 208 of the second pole 198 which extends the first passageway 154 of the second pole 198 through the rear handle section 138 of the rear housing 104 and projects rearwardly of the handle section 138. The extension tube 280 is made from electrically conductive material and is electrically connected to the second aluminium tube 208. A vacuum nozzle 152 is releasably attachable to the end of the extension tube 280 via a clip 282. The vacuum nozzle 152 is made from electrically conductive material and is electrically connected to the extension tube 280. The clip 282 comprises a first part formed on the vacuum nozzle 152 and a second part formed on the end of the extension tube 280. The first part comprises two pins 284, each pin 284 being mounted on the end of a resiliently deformable leg 286. The second part comprise two holes 288 formed through the side wall of the end of the extension tube 280 in corresponding locations to the pins 284. To attach the vacuum nozzle 152, the legs 286 are bent inwardly so that the pins 284 can slide inside of the end of the extension tube 280 as the vacuum nozzle 152 is slid into the extension tube 280. When the pins 284 align with the holes 288, the pins 284 are biased into the holes 288 by the resilient legs 286 bending back to their original position. Whilst the pins 284 are located in the holes 288, the vacuum nozzle 152 remains attached to the extension tube 280. To detach the vacuum nozzle 152 the pins 284 are pushed back into the apertures to disengage them from the holes 288. The nozzle 152 is slid out of the extension tube 280. The vacuum nozzle 152 can be attached to the hose of a vacuum cleaner. As the nozzle 152 can be easily attached and detached, a suitable design of nozzle 152 can be chosen depending on the type of vacuum cleaner utilised. Furthermore, if the nozzle 152 breaks it can be easily replaced.

Claims

Claims 1 A handheld pole sander for sanding, polishing, grinding or rubbing a work surface comprising: an elongate body (102) having two ends; a sanding head (100) attached via a pivot mechanism (110) to a first end of the elongate body (102); an electric motor (114) mounted on the sander, the electric motor (114) being electrically controlled by control electronics (144) which provides electronic control signals to activate the motor (114); wherein the sanding head (100) comprises: a hood (112); and an output spindle (118) which projects from the hood (112); wherein the electric motor (114), when activated, rotatingly drives the output spindle (118); wherein the elongate body comprises a first pole (196) and a second pole (198) which are capable of sliding in and out of each other in a telescopic manner; wherein the first pole (196) comprises a single aluminium tube with an internal wall (202) to form two passageways; wherein the second pole (102) comprises a first tube (206) and a second tube (208) mounted in parallel to the first tube (206), inside of the first tube (206); wherein an end of the second tube of the second pole locates inside an end of one of the passageways of the tube of the first pole; wherein an end of the tube and internal wall of the first pole which contains the end of the second tube of the second pole locates inside of an end of the first tube of the second pole.
2 A handheld pole sander as claimed in claim 1 wherein at least one seal (204, 210, 212) is located between the overlapping parts of the first pole and second pole (198); wherein a first seal is mounted on the end of the aluminium tube and internal wall (202) of the first pole (196) which over laps the second pole; wherein a second seal (210) is mounted on the end of the first tube (206) of the second pole which over laps the first pole and a third seal (212) is mounted on the end of the second tube of the second pole (208) which over laps the first pole; wherein the end of the second tube and the third seal of the second pole locates inside the end of one of the passageways of the tube of the first pole; wherein the end of the tube, internal wall and first seal of the first pole which contains the end of the second tube and the third seal of the second pole locates inside of the end of the first tube of the second pole.
3 A handheld pole sander as claimed in either of claims 1 or 2 wherein the first pole and/or second pole are manufactured from metal tubing and preferably, from aluminium tubing.
4 A handheld pole sander as claimed in either of claims 2, 3 or 4 wherein one of the passageways of the single tube of the first pole and the passageway of the second tube (206) of the second pole form a first passageway (154) which is used to transport air through the length of the elongate body (102).
A handheld pole sander as claimed in any of the previous claims wherein a second passageway (148) is formed by the other passageway of single tube of the first pole and the passageway formed between the first tube (206) and the second tube of the second pole, the second passageway forming a conduit through the elongate body (102).
6 A handheld pole sander as claimed in claim 5 wherein there is provided a rear housing (104) mounted on the end of the elongate body (102) remote from the sanding head; wherein the control electronics (144) for the electric motor (114) are mounted inside of the rear housing (104) adjacent the second end; wherein the electric motor (114) is mounted on the hood (112); wherein an electric cable (146) which connects between the control electronics (144) and the electric motor (114) passes through the conduit (148).