GB2420772A

GB2420772A - Electrically powered garden tool with retracting cable

Info

Publication number: GB2420772A
Application number: GB0426353A
Authority: GB
Inventors: Leonard Stockley
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-12-01
Filing date: 2004-12-01
Publication date: 2006-06-07
Anticipated expiration: 2024-12-01
Also published as: GB2420772B; GB0426353D0; GB2420772C

Abstract

An electrically powered garden tool 1 with a cable 16 supplying electricity thereto comprises a retractor unit 50 for retracting and storing the cable which biases the cable in a retracting direction and a manually actuated brake mechanism which is selectively operable upon the cable. The brake actuator 7 may also control the supply of electric power to the powered garden tool. The retractor unit may comprise a reel or drum which rotates as cable is extended from and rewound into the retracting unit. In use, the remote end of the cable is anchored at an anchoring point and additional cable is withdrawn from the retractor as the tool moves away from the anchor point, or slack in the cable is taken up by retractor unit as the tool moves towards the anchor point.

Description

POWERED GARDEN TOOLS

This invention relates to a safety modification for a powered garden tool, particularly a cutting tool such as an electric lawnmower.

While mowing the lawn with an electric lawnmower the operator must also control its power cable, generally lying free on the grass. The operator may inadvertently mow' the power cable, the sharp blades of the lawnmower cutting the cable, rendering the lawnmower temporarily unusable and in need of repair. It also presents the considerable danger that the live end of the power cable may come into contact with a person, before the cable can be disconnected from the power source. There is therefore a need for a safe and convenient mechanism for keeping the power cable away from the blades of the lawnmower while it is being operated.

According to a first aspect, the present invention provides an electrically powered garden tool having a power cable for supplying electric power thereto, the tool comprising a cable retractor unit for storing a length of power cable and for applying a retracting force to the cable when extended from the unit, the cable retractor unit including a braking mechanism for controlling the application of the retracting force to the cable, wherein the braking mechanism is operable using a manual actuator.

Preferably, the manual actuator that operates the braking mechanism also controls the supply of electric power to the tool.

In embodiment of the present invention, when the tool is being operated, a remote end of the extended cable is anchored at an anchoring point and the retracting force is applied to the cable such that either additional cable is withdrawn from the retractor unit as the tool is moved away from the anchor point or slack in the cable is taken up by the retractor unit as the tool is moved toward the anchor point.

In a lawnmower embodying the invention the cable is therefore maintained under tension while mowing the lawn and, by arranging that anchoring point and/or the cable outlet from retractor unit at a level above that of the cutting blades of the mower, the cable will always lie clear of the rotating cutting blades of the mower.

Other preferred features and advantages of the present invention will be apparent from

the following description and accompanying claims.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a lawnmower forming a first embodiment of the present invention; Figure 2 is a schematic view of a braking mechanism for the cable retractor unit; Figure 3 is a diagrammatic illustration of a cable outlet for a power cable fed out from the retractor unit; Figure 4 is a schematic diagram of the retractable and fixed power cables and their connection to the motor of the mower; Figures 5A and SB are a side view and a front view, respectively, of a cable strain peg; Figure 6 is a diagrammatic view of a power cable anchored to the ground by the cable strain peg of Figure 5; Figure 7 is a diagrammatic view of a power cable anchored to a wall by a cable strain bracket; Figure 8 is a perspective view of a lawnmower forming a second embodiment of the present invention, and Figure 9 is a perspective view of a lawnmower forming a third embodiment of the present invention.

Referring first to Figure 1 to 4, a rotary lawnmower I embodying the present invention includes an electric motor 32 for driving a rotating cutting blade (not shown) about a vertical axis. The motor 32 is disposed within a protective housing 31 and is supplied with power through a power cable which has a plug 5 for plugging into a power supply, such as a mains socket. The lawnmower itself is conventional and will not therefore be described in further detail.

The lawnmower 1 is fitted with a safety device that reduces or eliminates the risk of the power cable being inadvertently cut by the rotating cutter blade. The safety device comprises a cable retractor unit 50 which, in a preferred embodiment, includes a self-winding inner reel 13 disposed within a housing 12, the retractor unit storing a length of power lead 16 which can be unwound from the reel 13 against a spring bias and fed out from the housing 12 through a cable outlet 42 (Figures 1 and 2). In a preferred embodiment, a dual winding flat spring, configured to wind from one reel to another during tensioning thereof, may be used to provide the spring bias. Such an arrangement, available under the trade name "Pro-Reel", applies a more uniform tension to the cable, irrespective of the length of cable that is extended from the retractor unit, compared to a single spring arrangement.

The cable outlet 42 comprises a circle of nylon roller bearings 21 allowing the cable 16 to exit easily in any direction. As best seen in Figure 4, the innermost end of the power lead 16 is connected to a pair of bushes 46 which engage respective slip rings on a fixed plate 45 positioned beneath the reel 13. A fixed length of power cable 29 then connects the slip rings on the fixed plate 45 to a switch box 17 at the top of the mower handle 8, and a further fixed length of cable 30 is connected back from the switch box to the motor 32 within the motor housing 31. Any alternative arrangement which allows current to pass from the fixed cable 29 to the retractable power lead 16 may be used in place of the slip rings and bushes. As shown in Figures 1 and 3, a flexible conduit 3 carries the outer end of the power lead 16 from the outlet 42 of the retractor unit 50 to a similar cable outlet 4 at the top of the handle 8, the conduit running within or alongside the handle.

Figure 2 shows a braking mechanism for the inner self-winding reel 13 of the retractor unit 50 according to a preferred embodiment of the present invention. The self- winding reel 13 incorporates a single or dual spring biasing means (not shown) which biases the reel for rotation about a pin 40 in a direction that will wind cable onto the reel, the spring being tensioned when the reel is rotated in the opposite direction as cable is withdrawn from the reel. This self-winding mechanism is conventional and will not be described in further detail. One end of a brake cable 9 is connected to a spring-biased braking arm 20 that pivots about a pin 41 on the inside of the retractor housing 12, the braking arm 20 having a rubber brake block 10 that normally engages a corrugated or serrated surface of the inner reel 13 and prevents it rotating in the direction that winds cable on to the reel. The other end of the brake cable is connected to an operating lever 7 of the switch box 17 at the top of the handle 8. The power lead 16 passes freely through an aperture 18 in the brake arm 20 until a strain relief ball 14 at the inner end of the power lead prevents further extension, establishing the point beyond which the power cable does not extend and preventing excess strain being placed on electrical connections within the lawnmower. The power lead changes colour as this maximum extension is approached.

When the operating lever 7 is pulled, the spring 19 is compressed, disengaging the braking arm 20 from the inner reel 13 and leaving the reel free to rewind the power lead 16.

Referring to Figure 3, the cable outlet 4 is similar to the cable outlet 42 and comprises a circle of nylon roller bearings 21 allowing the power lead 16 to exit easily from the conduit 3 in any direction. The cable outlet 4 is attached to the handle 8 of the lawnmower, close to the switch box 17. The power lead 16 has a strain relief ball 6 fitted close to the plug 5, the ball being unable to pass through the outlet 4 and thereby preventing the retraction force on the lead exerting undue strain on the plug fittings and establishing the point beyond which the power lead does not retract.

Figure 4 shows the switch box 17 including two switches 33 and 34. The first switch 33 is controlled by the manually operable lever 7, which, in preferred embodiments, also controls the brake mechanism. The switch 33 is closed to start the motor 32 only if the second switch 34 has also been closed by a second manually operable actuator (not shown) which may be a push button on the switch box. The power lead 16, the fixed cables 29 and 30, and the brake cable 9 may all pass through the flexible conduit 3 in which case the conduit may be provided with separate channels to keep the cables separated from one another.

Figures 5A and 5B show a side view and a front view respectively, of a cable strain peg 25 having a spike 51 that is pushed into the ground. The peg has a pull-out handle 26 for easy extraction from the ground, a hammer block 27 which may be used should the ground be excessively firm, and a hook and eye arrangement 28 through which the power lead is threaded to secure the power lead to the peg.

Figure 6 shows the cable strain peg 25 fixed to the ground. The power lead 16 is threaded through the hook and eye arrangement 28 securing it. A portion 24 of the power lead beyond the cable strain peg may then lie loose and hazard free.

Figure 7 shows a cable strain bracket 23, which has a similar function to the cable strain peg 25 of Figures 5 and 6 except that the bracket is fixed to a wall.

In operation, a length of the power lead 16 is withdrawn from the retractor unit 50 and the plug 5 is inserted into a socket of a power supply. The power lead 16 is then anchored at a convenient point by threading it through the hook and eye arrangement 28 of either the cable strain peg 25 inserted in the ground (Figure 6), or the cable strain bracket 23 attached to a wall (Figure 7). By pulling the operating lever 7 of the switch unit 17 on the handle of the lawnmower, and actuating the additional safety switch 34, the lawnmower may be started.

Pulling the operating lever 7 not only closes the switch 33 to start the motor 32 (Figure 4) but also tensions the brake cable 9 so that the brake arm 20 (Figure 2)is mechanically lifted, against the bias of spring 19, from the self-winding reel 13 and a retraction force is exerted on the power lead, pulling it taut between the anchor point and the handle 8 of the mower, this tension being maintained while the mower is in use. Any direction in which the operator may wish to go can be easily accommodated by the roller bearings 21 at the cable outlet 4 (Figure 3) allowing the power lead to exit freely in any direction. As the operator moves away from the anchor point, additional lead is withdrawn from the reel 13 of the retractor unit, and as the operator moves towards the anchor point any slack is taken up. In this manner, the power lead 16 is kept away from the cutting blades of the mower at all times when the mower is in operation.

Additionally, since the power lead is fed out from the mower to the anchor point, and the length of the lead is automatically varied to compensate for the variation in the distance of the mower from the anchor point, the lead is at no time dragged over the ground or around obstacles such as trees or walls. Snagging of the lead and damage to it due to scuffing on such obstacles is therefore reduced or eliminated.

As the operator reaches the limit of the power lead's range, the colour of the cable feeding from the rewind device changes. Should the operator not heed this warning, the strain relief ball 14 on the power lead 16 close to the cable retraction unit 13, being unable to pass through the aperture 18 in the braking arm 20 (Figure 2), prevents undue strain on the fittings within the mower.

Once the operator has completed mowing, the plug 5 is disconnected from its socket, the power cable released from the cable strain peg 25 or bracket 23, and the operating lever 7 is actuated to rewind the power lead 16 on the reel 13 within the cable retractor unit 50 until the mower is required again.

Figure 8 shows an alternative arrangement for a Iawnmower forming a second embodiment of the present invention. The features of this embodiment corresponding to the features of the above described first embodiment are assigned like reference numerals.

This second embodiment is similar to the first embodiment in that the power lead 16 is carried in a conduit 3 running alongside the operating handle 8 of the lawnmower 1.

However, the arrangement differs from the lawnmower of Figure 1 in that, as shown in Figure 8, the conduit is telescopically extendable so that, in use, the conduit may extend beyond (i.e. behind) the person operating the mower. This arrangement prevents the tensioned cable 16 from inhibiting the movement of the mower by the operator, particularly when turning and otherwise manoeuvring the lawnmower 1.

The conduit 3 is preferably formed from a plastics or nylon material that enables the conduit 3 to easily glide during telescopic extension and retraction thereof, and, in the illustrated embodiment, is arranged to pivot with the handle 8 when collapsing the lawnmower for more compact storage. In addition to the telescopic conduit 3, an electrical socket 52 is provided on top of the housing 31 of the cable retractor 50 and motor.

Figure 9 shows yet another arrangement for a lawnmower forming a third embodiment of the present invention. The features of this embodiment corresponding to the features of the first and second embodiments are assigned like reference numerals.

In this third embodiment, the cable retracting unit 50 is mounted in a rotatable drum 54 which rotates on the housing 31 of the motor as the power lead 16 unreels from, or reels back into, the self-winding reel housed therein. The power lead 16 extends from the self-winding reel through a cable outlet 42 on the side of the drum 54. In this embodiment, although the cable outlet 42 is typically above the level of the cutting blades of the mower (Figure 9), in order to ensure the cable 17 is kept clear of the cutting blades at all times it is preferable to arrange the anchoring point at a position above the highest level of the ground of the lawn being mowed.

Various modifications and changes may be made to the described embodiments. For example, whilst the described braking mechanism is activated mechanically, an electrically operated brake may be used. In this case, the manually operated actuator (corresponding to lever 7) may control an electrical switch to supply power to, or remove power from, e.g. a solenoid, in order to apply or release the brake from the drum of the self-winding reel of the cable retractor. In this case, a battery may be provided to enable the release of the brake in order to wind the cable into the reel after use.

Although the first and second embodiments employ a conduit to carry the power cable alongside the handle 8 of the lawnmower 1, this is not essential. Any means of supporting the cable whilst enabling it to run alongside the handle may be used, for instance ring-shaped clips. However, the use of a conduit prevents contamination from grass cuttings, moisture and the like.

In all of the described arrangements, conventional measures are employed for moisture and contaminate prevention. For example, one or more moisture drain holes may be provided in, the underside of the conduit, the underside of the pivot housing of the telescopic conduit or at the base of the conduit. Such moisture drain holes are typically covered with nylon or steel gauze to prevent contamination by grass cutting and the like. This ensures that any moisture that may run down the cable is prevented from entering the housing of the retractor unit. In addition, all internal electrical parts are typically sealed separately within respective casings to prevent contamination.

This is particularly important in the third of the described embodiments.

The skilled person will appreciate that may other types of mechanical or electrical controlled braking mechanism will be suitable from preventing the rotation of the self-winding reel. The present invention is intended to include all such braking mechanisms.

Although, in the described embodiments, the braking mechanism is actuated by the same operating lever as a power switch, in other embodiments a separate actuator such as a lever or switch may be provided for the braking mechanism.

It is intended to include all such variations, modifications and equivalents which fall within the scope of the present invention, as defined in the accompanying claims.

Claims

CLAiMS: 1. An electrically powered garden tool having a power cable for

supplying electric power thereto, the tool comprising a cable retractor unit for storing a length of power cable and for applying a retracting force to the cable when extended from the unit, the cable retractor unit including a braking mechanism for controlling the application of the retracting force to the cable, wherein the braking mechanism is operable using a manual actuator.
2. A tool according to claim 1, wherein the manual actuator also controls the supply of electric power to the tool.
3. A tool according to claim 2, wherein the manual actuator controls the braking mechanism so that the retracting force is applied to the cable when it is actuated to turn on power to the tool, and the retracting force is not applied to the cable when it is released to turn off power to the tool.
4. A tool according to claim 1, 2 or 3, wherein, in operation, the remote end of the extended cable is anchored at an anchoring point and the retracting force is applied to the cable such that additional cable is withdrawn from the retractor unit as the tool moves away from the anchor point or slack in the cable is taken up by the retractor unit as the tool moves toward the anchor point.
5. A tool according to claim 4, wherein the remote end of the cable has a plug and wherein anchoring means are provided for anchoring the cable at the anchoring point either before or after the plug is plugged into a power supply socket.
6. A tool according to claim 4 or claim 5, wherein the anchoring point is positioned above the level of a blade of the tool.
7. A tool according to any one of claims I to 6, wherein the cable retractor unit is mounted on, or is integrated within, the garden tool.
8. A tool according to any one of claims I to 7, wherein the cable retractor unit further comprises a resilient biasing means for biasing the cable in a direction to retract the cable so as to provide the retracting force, whereby the cable is extended from the retracting unit against bias of the biasing means.
9. A tool according to claim 8, wherein the cable retractor unit further comprises a mechanical or electrical braking mechanism which prevents the biasing force from being applied to the cable until a brake is released.
10. A tool according to claim 9, wherein the cable retractor unit further comprises a (self-winding) reel for storing said length of cable, the reel comprising a drum that rotates as cable is extended from and retracted into the retracting unit, wherein the braking mechanism includes means to prevent rotation of the drum when the brake is applied.
11. A tool according to claim 10, wherein the (self-winding) reel is contained within a housing having a cable outlet, and the cable is withdrawn from the housing through a flexible conduit having a conduit outlet, wherein the flexible conduit may be telescopically extended beyond the tool operator.
12. A tool according to claim Ii, wherein the cable outlet and/or the conduit outlet comprises an array of bearings bounding the outlet.
13. A tool according to any one of claims I to 12, wherein the diameter of the cable is enlarged at a point between the plug and the cable outlet, the enlargement being unable to pass through the outlet such that the retraction force is not applied to the plug.
14. A tool according to claim 9, wherein the braking mechanism includes a brake cable for operating the said brake on the retractor unit.
15. A tool according to claim 14, wherein a portion of the brake cable is also contained within the said conduit.
16. A tool according to claim 14 or claim 15, wherein one end of the brake cable is connected to the manually operable actuator attached to the tool.
17. A tool according to claim 14, 15 or 16, wherein the braking mechanism is operated mechanically and comprises a spring-biased pivoted braking arm connected to the other end of the brake cable for applying a braking force to the retractor unit, and the manually operable actuator comprises an operating lever for urging the braking arm against its spring bias to disengage the arm from the retractor unit.
18. A tool according to claim 14, 15 or 16, wherein the braking mechanism is operated electrically and comprises a spring-biased pivoted braking arm connected to the other end of the brake cable for applying a braking force to the retractor unit, and the manually operable actuator comprises an operating lever for supplying electrical current to a solenoid which, when activated, urges the braking arm against its spring bias to disengage the arm from the retractor unit.
19. A tool according to claim 17 or claim 18, wherein the braking arm has an aperture through which the power cable passes freely.
20. A tool according to claim 19, wherein an inner end portion of the power cable wound on the retractor unit has an enlargement that will not pass through the aperture in the braking arm.
21. A tool according to claim 10, wherein an inner end of the cable wound on the (self-winding) reel of the retractor unit is connected via slip rings and bushes to a fixed length of power cable extending from the self-winding reel to a switch unit, and a further fixed length of power cable connects the switch unit to a motor.
22. A tool according to claim 21, wherein the switch unit includes a first switch and a second switch, where the first switch is operable by said manual actuator.
23. A tool according to claim 5, wherein the anchoring means includes a threading arrangement for retaining the power cable, and a pointed member for insertion in the ground.
24. A tool according to claim 23, wherein the anchoring means further comprises a pull-out handle for extracting the pointed member from the ground.
25. A tool according to claim 23 or 24, wherein the anchoring means further comprises a flat surface for hammering the pointed member into the ground.
26. A tool according to claim 5, wherein the anchoring means comprises a bracket for attachment to a structure fixed to the ground.
27. A tool according to any one of the preceding claims wherein the tool comprises an electric lawnmower.
28. An electrically powered garden tool substantially as hereinbefore described with reference to, and as illustrated in, any one or more of the accompanying drawings.