WO2011032574A1

WO2011032574A1 - Tools

Info

Publication number: WO2011032574A1
Application number: PCT/EP2009/006776
Authority: WO
Inventors: Mikael Racov; Johan Svennung; Mia Herou
Original assignee: Husqvarna Ab
Priority date: 2009-09-19
Filing date: 2009-09-19
Publication date: 2011-03-24

Abstract

A battery-powered portable tool (1) such as a grass trimmer comprising an elongate member (2) having a first end and a second end, the tool being provided with a driven member (3) at the first end of the elongate member (2), a motor (7) arranged to drive the driven member (3) and an adjustable handle (9) having an attachment mechanism (10) whereby the adjustable handle (9) can be fixed relative to the elongate member (2) at a plurality of handle positions along the length of the elongate member (2), in which the tool (1) further comprises a battery pack (8) comprising a battery arranged to provide electrical power in order to drive the motor (7), and in which the battery pack (8) can be attached to the elongate member (2) at the second end thereof a plurality of battery positions along the length of the elongate member (2). Thus, the battery pack (8) can be used to balance the movement of the adjustable handle (9), so that the tool (1) can be balanced at different positions of the adjustable handle (9).

Description

TOOLS

This invention relates to battery-powered portable tools. Battery-operated portable tools are becoming more and more popular, as they allow a user to operate a power tool away from a fixed source of electricity. Grass trimmers can be provided as such battery-operated portable tools; a rotary cutting element is provided at one end of an elongate member, which can be driven by an electric motor powered by a battery. Two handles are provided for the user; one at the distal end of the elongate member from the cutting element, often carrying a speed control; and one intermediate handle between the two ends.

The intermediate handle can be adjustable in position along the elongate member, so as to allow for different height users; when held at the appropriate angle so that the cutting element rotates in a horizontal plane, the cutting element should be at just above ground height. Evidently, for users of differing heights, the distance between the intermediate handle and the cutting element will need to be adjusted to achieve this.

However, adjusting the position of the intermediate handle can lead to the case where the tool is not balanced about the intermediate handle. This will lead to the weight of the tool applying a torque to the tool about the intermediate handle either forcing the cutting edge up or down, depending on which side of the intermediate member the centre of gravity of the tool is along the elongate member. The user will therefore constantly have to act against this torque, which is tiring and unergonomic.

GB 2 348 101 proposes the use of removable weights for balancing such a trimmer, but this is inconvenient because it requires the user to add or replace extra components to the trimmer. The weights can be easily lost, P2552PC00 2

and mean that the trimmer will be heavier than otherwise would be the case.

According to a first aspect of the invention, there is provided a battery- powered portable tool comprising an elongate member having a first end and a second end, the tool being provided with a driven member at the first end of the elongate member, a motor arranged to drive the driven member and an adjustable handle having an attachment mechanism whereby the adjustable handle can be fixed relative to the elongate member at a plurality of handle positions along the length of the elongate member, in which the tool further comprises a battery pack comprising a battery arranged to provide electrical power in order to drive the motor, and in which the battery pack can be attached to the elongate member at the second end thereof a plurality of battery positions along the length of the elongate member.

According, by providing a battery pack that can be connected to the elongate member at multiple positions, the position of the centre of gravity along the elongate member can be adjusted so as to account for movement of the adjustable handle. Typically, the user would adjust the adjustable handle so that the driven member was at an appropriate height when the tool was supported by the user using the adjustable handle. They could then adjust the position of the battery pack so that the tool was approximately balanced about the adjustable handle (that is, the centre of gravity was approximately at the same position along the elongate member as the adjustable handle).

A further handle may be provided at the second end of the elongate member. This allows two-handed operation of the tool; because the tool can be balanced about the adjustable handle with the adjustable handle in a plurality of positions, this operation can be more comfortable and easy for the user than otherwise would be the case. The further handle may be part P2552PC00 3

of the battery pack, or may be part of or attached to the second end of the elongate member. The further handle may be provided with a throttle control, by means of which the speed at which the motor drives the driven member can be controlled.

The battery pack may be attachable to the elongate member only at a plurality of discrete positions on the elongate member; in such a case a fitting, typically a snap fitting, can provided at each of the discrete positions. The battery pack may comprise a corresponding fitting to those on the elongate member. The fittings may physically secure the battery pack to the housing, and also transmit electrical power from the battery in the battery pack to the motor.

In such a case, the adjustable handle may be attachable to the elongate member only at a plurality of discrete positions on the elongate member. Each of the discrete positions at which the adjustable handle is attachable to the elongate member may correspond to one of the discrete positions at which the battery pack can be attached to the elongate member, such that when the battery pack and the elongate member are attached to the elongate member at corresponding positions, the tool is balanced about the first handle.

Alternatively, the battery pack may be capable of attachment to the elongate member over a continuous range of positions along the elongate member. Typically, the adjustable handle may also be capable of attachment to the elongate member over a continuous range of positions along the elongate member. The tool may be provided with two sets of indicia, one positioned about the range of positions of the battery pack and one positioned about the range of positions of the adjustable handle, the indicia indicating the appropriate position to achieve a balanced tool of one of the adjustable handle and the battery pack given the position of the other of the adjustable handle and the battery pack. Typically, such indicia could P2552PC00 4

comprise a pair of numbered scales, whereby positioning of the adjustable handle and the battery pack at the same number on the two scales leads to a balanced tool. The driven member typically will comprise a cutting element, such as a blade or cutting line. The tool may be a trimmer, such as a grass trimmer.

According to a second aspect of the invention, there is provided a method of using a battery-operated power tool according to the first aspect of the invention, comprising moving the adjustable handle to a desired position along the length of the elongate member and moving the battery pack along the length of the elongate member so as to balance the tool.

By balancing the tool, we typically mean moving the centre of gravity of the tool along the length of the elongate member to be at the position of the adjustable handle along the length of the elongate member. Typically, the step of moving the adjustable handle or the battery pack to a position along the length of the elongate member will comprise the step of fixing it at that location.

There now follows, by way of example only, embodiments of the present invention, described with reference to the accompanying drawings, in which: Figure 1 shows a grass trimmer according to a first embodiment of the invention;

Figure 2 shows a grass trimmer according to a second embodiment of the invention;

Figure 3 shows an detailed, enlarged view of area A of Figure 2; and P2552FCU0 5

Figure 4 shows a front elevation of a battery pack for use with the grass trimmer of Figure 2. A battery-operated power tool according to a first embodiment of the invention, of the form of a grass trimmer 1 , is shown in Figure 1 of the accompanying drawings. This comprises an elongate member of the form of a pole 2. At a first end of this pole 2, there is provided a cutting head 3. As is common in grass trimmers (also known as strimmers), the head 3 comprises a shield 4 and a rotating part 5. A length of nylon (or other suitable polymer) thread 6 extends from the rotating part 5; by rotating the rotating part 5 with motor 7 at high speed, grass will be cut by the thread 6.

At the second end of the pole 2 distal from the first end, there is provided a battery pack 8. This battery pack contains a battery (not shown) by means of which the motor 7 can be driven. The battery pack 8 also comprises a handle for a user and a throttle by means of which the speed of the motor 7 can be controlled (both not shown). Intermediate the first and second ends of the pole 2, there is provided an adjustable handle 9, which can slide along the pole 2. A fixing mechanism 10 is provided by means of which the handle 9 can be fixed relative to the pole at any desired position; the drawings show two example positions of the adjustable handle 9, one in solid lines and the other in dashed lines.

However, the movement of the adjustable handle 9 may mean that the adjustable handle is no longer at the centre of gravity of the trimmer 1 along the pole 2. This would lead to an unbalanced feel of the trimmer 1 , and tire the user more quickly when using the trimmer 1. As such, the battery pack 8 is also slidable relative to the pole, and can be fixed relative to the pole by a fixing mechanism similar to that of the adjustable handle (but which is not shown). P2552PCU0 6

Because the battery pack 8 is relatively dense due to the presence of the battery therewithin, the battery pack serves as a convenient counterweight to the cutting head 3. As such, movement of the battery pack 8 along the pole 2 will move the centre of gravity of the trimmer 1 , so that the centre of gravity can be moved to the location of the adjustable handle 9 along the pole 2. As such, a balanced trimmer 1 can be achieved once more.

In order to adjust the trimmer, the user could be allowed to simply adjust the positions of the adjustable handle 9 and the battery pack 8 until the trimmer 1 feels comfortable. However, the trimmer 1 can be provided with indicia to indicate the appropriate position of the battery pack 8 along the pole 2 for a given position of the adjustable handle 9 along the pole. In the present embodiment, this could be pair of numbered scales, one adjacent to the adjustable handle 9 and the other adjacent to the battery pack 8. As such, the beginning of the scale, say number "1" could appear at positions 1 1a and l ib on the pole 2, adjacent to the positions of the adjustable handle 9 and the battery pack 8 shown in solid lines, whereas the end of the scale, say number "10", could appear at positions 12a and 12b adjacent to the positions of the adjustable handle 9 and the battery pack 8 shown in dotted lines.

A grass trimmer 21 according to a second embodiment of the invention is shown in Figures 2 to 4 of the accompanying drawings. Features of this embodiment equivalent to those of the first embodiment are given the same reference numerals raised by 20.

In this embodiment, the adjustable handle 29 can be fixed to the pole 22 at a plurality of fixed locations where the fixing mechanism 30 can place a pin through a hole in the pole (not shown). Thus, the adjustable handle 29 has a plurality of discrete positions where it can be fixed to the pole 22. P2552PCU0 7

At the second end of the pole 22 distal from the first end having the cutting head 23, a handle 35 is provided; a throttle 36 (not shown in detail) is also provided in the handle 35 for controlling the speed of the motor 27. The handle 35 provides a plurality of discrete locations for the battery pack 28 to be attached. The battery pack 28 comprises a snap-locking mechanism having a pair of flexible tabs 38. These tabs can be inserted into corresponding holes 39 in the handle 35 and engage the hole so as to resist removal; each set of holes 39 define a position of the battery pack relative to the handle. Contacts 40 on the top surface of the battery pack 28 provide electrical connection of the battery (not shown) within the battery pack 28 to the motor 27. Squeezing the tabs 38 together allows the battery pack 28 to be removed. As such, the battery pack 28 can be mounted relative to the pole 22 at a plurality of positions along the pole's length. By snap-fitting the battery pack into different sets of holes 39, this position can be changed, to allow the position of the centre of gravity of the trimmer 21 to be moved to accommodate for fixing of the adjustable handle at different positions along the length of the pole. There is a one-to-one correspondence between the positions at which the adjustable handle 29 can be attached to the pole and the positions at which the battery pack 28 can be attached to the handle, so that a balanced trimmer 21 is provided at each pair of -positions. The corresponding positions may be labelled with corresponding indicia, for instance numbers.

Claims

P2552PCU0 8 CLAIMS

1. A battery-powered portable tool comprising an elongate member having a first end and a second end, the tool being provided with a driven member at the first end of the elongate member, a motor arranged to drive the driven member and an adjustable handle having an attachment mechanism whereby the adjustable handle can be fixed relative to the elongate member at a plurality of handle positions along the length of the elongate member, in which the tool further comprises a battery pack comprising a battery arranged to provide electrical power in order to drive the motor, and in which the battery pack can be attached to the elongate member at the second end thereof a plurality of battery positions along the length of the elongate member.

2. The tool of claim 1, in which the battery pack is attachable to the elongate member only at a plurality of discrete positions on the elongate member. '

3. The tool of claim 2, in which the adjustable handle is attachable to the elongate member only at a plurality of discrete positions on the elongate member.

4. The. tool of claim 2 or claim 3, in which each of the discrete positions at which the adjustable handle is attachable to the elongate member corresponds to one of the discrete positions at which the battery pack can be attached to the elongate member, such that when the battery pack and the elongate member are attached to the elongate member at corresponding positions, the tool is balanced about the first handle.

5. The tool of any of claims 2 to 4, in which a fitting, typically a snap fitting, is provided for the battery pack provided at each of the discrete positions of the battery pack. P2552PC00 9

6. The tool of claim 1 , in which the battery pack is capable of attachment to the elongate member over a continuous range of positions along the elongate member.

7. The tool of claim 6, in which the adjustable handle is capable of attachment to the elongate member over a continuous range of positions along the elongate member.

8. The tool of claim 6 or claim 7, in which the tool is provided with two sets of indicia, one positioned about the range of positions of the battery pack and one positioned about the range of positions of the adjustable handle, the indicia indicating the appropriate position to achieve a balanced tool of one of the adjustable handle and the battery pack given the position of the other of the adjustable handle and the battery pack.

9. The tool of any preceding claim, being a trimmer, such as a grass trimmer.

10. A method of using a battery-operated power tool according to any preceding claim, comprising moving the adjustable handle to a desired position along the length of the elongate member and moving the battery pack along the length of the elongate member so as to balance the tool.

1 1. The method of claim 10, in which the step of moving the adjustable handle or the battery pack to a position along the length of the elongate member comprises the step of fixing it at that location.