IMPROVED BRANCH CUTTER

Abstract

The invention relates to a branch cutter (10), namely a motor-powered tool having a circular saw blade used for cutting tree branches and the like. The periphery of the saw blade is at least partially covered by a protective housing (24), the housing having a first opening (52) to expose a first portion of the periphery of the saw blade, and a second opening (54) to expose a second portion of the periphery of the saw blade. The provision of two housing openings exposing two portions of the periphery of the saw blade increases the utility and ease of use of the branch cutter.

Claims

1. A branch cutter (10) having a circular saw blade (20) and a motor to drive the saw blade to rotate, the periphery of the saw blade being at least partially covered by a housing (24), the housing having a first opening (52) to expose a first portion of the periphery of the saw blade, the housing having a second opening (54) to expose a second portion of the periphery of the saw blade.

2. The branch cutter according to claim 1 in which the first opening (52) and the second opening (54) are spaced apart around the circumference of the saw blade.

3. The branch cutter according to claim 1 which the first opening (52) and the second opening (54) are located so that a part of the first portion of the saw blade and a part of the second portion of the saw blade are diametrically opposed.

4. The branch cutter according to claim 1 having a cutter head (18) on which the saw blade (20) is mounted, the cutter head housing the motor and having a longitudinal axis (A-A), the centre of the saw blade (20) being offset (O) from the longitudinal axis (A-A).

5. The branch cutter according to claim 1 in which the circumferential extent of the first opening (52) and the circumferential extent of the second opening (54) are substantially identical.

6. The branch cutter according to claim 1 in which the radial extent (R) of the first opening and the radial extent of the second opening are substantially identical.

7. The branch cutter according to claim 1 in which the shape and size of the first and second openings (52, 54) are substantially identical.

8. The branch cutter according to claim 1 having an operating handle (12), in which the second opening (54) is closer to the operating handle (12) than the first opening (52).

9. The branch cutter according to claim 8 in which the operating handle (12) has a longitudinal axis, and in which the first opening (52) spans the longitudinal axis of the handle.

10. The branch cutter according to claim 1 in which the first opening (52) has a leading edge (60A) and trailing edge (62A), and in which the trailing edge of the first opening projects beyond the saw blade (20) further than the leading edge of the first opening.

11. The branch cutter according to claim 1 in which the second opening (54) has a leading edge (60B) and trailing edge (62B), and in which the trailing edge of the second opening projects beyond the saw blade (20) further than the leading edge of the second opening.

12. The branch cutter according to claim 10 in which the trailing edge (62A) of the first opening (54) and/or the trailing edge (62B) of the second opening (54) carries teeth or other formations adapted to hold a branch in engagement with the rotating saw blade in use.

13. The branch cutter according to claim 1 in which the saw blade (20) is driven to rotate by a pinion engaging its saw teeth (42).

14. The branch cutter according to claim 13 in which the pinion is connected to the motor by way of a flexible drive belt (36).

15. The branch cutter according to claim 1 in which the housing (24) covers parts of one side of the saw blade (20), the other side of the saw blade being largely exposed.

16. The branch cutter according to claim 15 having a bearing for the saw blade (20), the saw blade being removable and replaceable, the branch cutter having a removable fastener (26) for securing the saw blade (20) to the bearing, the fastener being fitted from the largely exposed side of the saw blade.

17. The branch cutter according to claim 16 in which the fastener (26) is located in a boss (30) which surrounds the fitted fastener.

18. The branch cutter according to claim 17 in which the boss has at least one buttress (32).

19. A branch cutter (10) having a cutter head (18) upon which a circular saw blade (20) is mounted, a motor housed by the cutter head and connected to the saw blade to drive the saw blade to rotate in use, the periphery of the saw blade being at least partially covered by a housing (24), the housing having a first opening (52) to expose a first portion of the periphery of the saw blade, the housing having a second opening (54) to expose a second portion of the periphery of the saw blade, the cutter head having a longitudinal axis (A-A), the centre of the saw blade (20) having a fixed offset (O) from the longitudinal axis (A-A), the first opening (52) having a leading edge (60A) and a trailing edge (62A), the trailing edge of the first opening projecting beyond the saw blade (20) further than the leading edge of the first opening, the second opening (54) having a leading edge (60B) and a trailing edge (62B), the trailing edge of the second opening projecting beyond the saw blade (20) further than the leading edge of the second opening, the branch cutter having an operating handle (12), the second opening (54) being closer to the operating handle (12) than the first opening (52).

Description

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which:

[0032] FIG. 1 is a perspective view of a branch cutter according to the present invention;

[0033] FIG. 2 is a side view of a part of the branch cutter;

[0034] FIG. 3 is an underside view of the part of the branch cutter of FIG. 2, with a part of the cover removed; and

[0035] FIG. 4 is a top plan view of the part of the branch cutter of FIG. 3.

DETAILED DESCRIPTION

[0036] The branch cutter 10 comprises a handle 12 having a (removable and rechargeable) battery 14 and an actuating switch 16. The battery and switch are connected to a motor (not seen) within the cutter head 18. The motor drives a circular saw blade 20 to rotate, as explained below.

[0037] In this embodiment the cutter head 18 is removable from the handle 12, by way of a releasable connection 22. The same handle 12 can therefore be used with other tools, including a hedge trimmer for example. In other embodiments a releasable connection is not required and the cutter head 18 is permanently secured to the handle 12.

[0038] The saw blade 20 is mounted to a bearing (not seen) at its centre by way of a releasable fastener 26. As better seen in FIG. 4 the fastener 26 is a cross-headed bolt which clamps a boss 30 against the surface of the saw blade 20, the saw blade having a small hole (not seen) at its centre through which the fastener 26 can pass. In this embodiment the hole is circular and is only slightly larger than the diameter of the shaft of the fastener 26 so that the insertion of the fastener serves to position the blade 20 centrally relative to its bearing (not seen); in other embodiments the hole is larger and accommodates a locating projection on the underside of the boss 30.

[0039] The boss 30 has four buttresses 32 which can be gripped by the user when the fastener 26 is being tightened and/or loosened, so as to hold the saw blade 20 against rotation during removal and fitment.

[0040] As seen in FIG. 2, the head of the fastener lies inside the sleeve 38 of the boss 30. The boss 30 therefore also protects the fastener 26 during use by reducing the likelihood that a branch being cut, or a neighbouring branch, or flying sawdust, will engage the fastener 26. The likelihood of the fastener 26 becoming unintentionally loosened is thereby much reduced. As with the known branch cutters and similar tools, the saw blade 20 rotates in a direction (counter-clockwise as viewed in FIG. 4) which acts to tighten the fastener 26.

[0041] As shown in relation to FIG. 3, the motor is connected to a drive pulley 34 which drives a flexible belt 36, the flexible belt in turn rotating a driven pulley 40 which is connected to a pinion (not seen) which engages the saw teeth 42 at the periphery of the saw blade 20. The pinion is located underneath a (non-rotating) cover 46 which is visible in FIGS. 1,2 and 4. It will be understood that the pinion has teeth which cooperate with the saw teeth 42, the pinon teeth ideally being shaped to maximise the area of engagement with the saw teeth 42 so as to minimise the point loading and thereby the wear upon the saw teeth.

[0042] Whilst the flexible belt 36 is designed to be substantially inflexible, in practice it will have some resilience and will therefore be able to absorb some of the stresses between the pinion and the saw teeth 42 and thereby reduce the maximum forces therebetween, so as to reduce the likelihood of damage to the pinion and/or saw teeth 42 in use.

[0043] The cutter head 18 has a housing 24 for the saw blade 20. It will be seen from FIGS. 3 and 4 that the housing 24 covers a part of only one side of the saw blade 20, so that the boss 30 and fastener 26 are permanently exposed and permanently accessible. Exposing one side of the saw blade 20 allows sawdust and the like to move away from the blade and thereby reduces the number of places at which sawdust, sap and other debris can become trapped (and compressed) within the cutter head 18.

[0044] The housing 24 extends beyond certain parts of the saw blade 20 and the extended parts are stepped around the periphery of the saw blade 20 so as to provide surfaces 50 which overlie and partially surround the saw teeth 42. The housing 24 thereby prevents inadvertent contact with the saw teeth. Accordingly, as seen in FIG. 2 in particular, the housing 24 covers a large proportion of the saw teeth 42.

[0045] The saw teeth 42 are, however, exposed at a first housing opening 52 and at a second housing opening 54. Thus, unlike the known branch cutters the saw blade 20 of the present branch cutter is exposed at two separate housing openings, providing two separate cutting regions. The first and second housing openings 52, 54 in this embodiment have the same radial extent R and the same peripheral extent (i.e. the circumferential distance between the leading edge 60A and trailing edge 62A of the first opening 52 is the same as the circumferential distance between the leading edge 60B and trailing edge 62B of the second opening 54), but this is not necessarily the case.

[0046] In practice, it is expected that for most of the time the branch cutter 10 will be used to cut branches which are smaller than the radial extent R, and the user will typically cut those branches by way of the saw teeth 42 exposed at the first housing opening 52, with the user pushing the cutter head 18 away from himself in common with the prior art branch cutter HT04. When it is desired to cut branches which are thicker than the radial extent R, or when it is desired to cut high branches from below, the user will typically use the saw teeth exposed at the second housing opening 54.

[0047] Typically, when using the saw teeth exposed at the second housing opening 54, the user will hold the branch cutter 10 with the second opening 54 facing downwardly and towards the user; the branch can then be cut by moving the cutter head 18 downwardly and slightly towards the user. If the branch is thicker than the radial extent R the user can (previously or subsequently) reposition the cutter head to cut through another part of the branch by way of the saw teeth exposed at the first opening 52, the cutter head being moved away from the user (and perhaps also slightly upwardly) as the branch is cut. It will be understood that the user does not have to reposition himself, or to reposition the branch cutter in his hands, in order to undertake both of these cutting operations.

[0048] It will be seen that the second opening 54 is not diametrically opposed to the first opening 54, though in other embodiments the openings could be diametrically opposed if desired. However, a part of the second opening 54 is diametrically opposed to a part of the first opening 52, so that the two openings can be used to cut a branch in two substantially opposing directions. It will be understood that a part of the first and second openings being diametrically opposed means that the ends of a chosen diameter of the saw blade lie in the respective first and second openings.

[0049] The diametrical opposition of parts of the openings 52,54 is achieved by offsetting the centre of the blade from the longitudinal axis A-A (FIG. 4), in this embodiment by an offset O. The offsetting enables the desired separation of the first and second openings whilst still having the first opening spanning the longitudinal axis A-A. This positioning of the first opening is highly desirable as it allows the user to push the blade 20 against a branch to be cut with the line of force acting directly along the longitudinal axis A-A (and consequently along the longitudinal axis of the handle 12 in this embodiment).

[0050] The direction of blade rotation in the orientation of FIG. 4 is anti-clockwise. During use the branch is driven away from the leading edge 60A (or 60B as applicable) and towards the trailing edge 62A (or 62B as applicable). The trailing edges 62A,B have a greater radial extent that the leading edges 60A,B so as to reduce the likelihood that a branch is forced over the trailing edge and away from the saw teeth 42. In other embodiments the trailing edges 62A,B can carry fixed teeth or be roughened so as to reduce the likelihood that a branch will move away from the saw teeth 42 during cutting.