Applicant: HUSQVARNA AB ₃ S-561 82 HUSKVARNA, Sweden Case P1673 PCT

HANDLE MEMBER

TECHNICAL FIELD

The present invention relates to a handle member for a motorized, handheld tool, including at least one substantially closed volume, a handle and a joint between two parts of the handle member, wherein the joint protrudes a distance beyond the surrounding surfaces.

BACKGROUND ART

Many handheld tools, such as chain saws, employ the two-mass principle, wherein the handle or handles and the fuel tank are separated from the engine. Hereby, and as there are springs suspending the engine base on a handle member, vibrations in the handle or handles are greatly reduced. This provides for better working conditions for the user.

The engine base includes the engine with its movable parts, a centrifugal clutch to the chain, a chain brake and a kickback guard. The handle member includes a front and a rear handle, as well as a fuel tank.

The rear handle is in general formed integrally with the fuel tank in the handle member, preferably from a plastics material. The handle member is manufactured by injection molding in two separate parts, which are not necessarily identical, but which are intended to be joined together along a circumferential line. The method of joining the two parts of the handle member is in general vibration welding, which includes a series of vibrations with a high frequency and a low amplitude, resulting in a joint along the circumferential line.

Since vibration welding of two pieces requires a sufficient thickness of the material to be welded, the walls of the handle member in several places have a greater thickness in the area of the joint. This will in turn mean that the weld will in several places be located at a

circumferential protuberance, extending a distance from the surrounding surfaces. Especially on the underside of the handle member this means that there is a protruding ridge, the weld, along the underside of the handle member, i.e. on the underside of the tool. When placing the tool on the ground this often means that the tool does not stand in a steady position but tends to lean over towards one side or the other. When cutting branches with a chain saw the underside of the handle unit will sometimes be pushed over logs and branches. This tends to dirty and scratch the underside of the tool thereby impairing its appearance.

PURPOSE OF THE INVENTION

The purpose of the invention is to substantially reduce the above mentioned problems.

SOLUTION

The objects forming the basis of the present invention will be attained for the handle member disclosed by way of introduction if this is characterized in that at least one rib is disposed at a distance from the joint on the underside of the handle member. Preferably the rib/ribs runs in a longitudinal direction.This has the further advantage of steering the tool in a longitudinal direction when pushed over a log or branch.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will now be described in greater detail below, with particular reference to the accompanying drawings. In the accompanying drawings:

Fig. 1 is a side view of a chain saw with a handle member according to the invention;

Fig. 2 is a perspective view of the handle member according to the invention;

Fig. 3 is a bottom view of the handle member according to the invention;

Fig. 4 is a section along the line A-A in Fig. 3; and

Fig. 5 is a view according to Fig. 4 of an alternative embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENT

In the following description words and expressions such as underside, bottom etc. are used.

These words should be interpreted as referring to the chain saw in a normal position of use and storage, such as the position shown in Fig. 1.

In Fig. 1 a chain saw 1 including a handle member 2 according to the invention is shown.

An engine base 3 includes an engine, which is connected to a chain 4 on a bar 5. The handle member 2 includes a rear handle 6, which typically is integral with a fuel tank 9. A front handle 7 is supported on the handle member 2, and the handle member 2 and the engine base 3 are joined together in a manner previously known in the art. Various safety features, such as a kickback guard 8 are also known from the state of the art.

Fig. 2 displays the handle member 2 in a perspective view from below. Here it is clearly visible that the rear handle 6 is integrally formed with the fuel tank 9. A bridge portion 10 extends in the forward direction to support the front handle 7, which is not shown in this drawing. Also the engine base 3 would be placed above the bridge portion 10 in the complete chain saw 1.

The handle member 2 is manufactured from a plastics material, as is known from the state of the art, in two pieces by injection molding. The two pieces are joined together by vibration welding at a joint 11. The joint 11 extends circumferentially around the handle member 2. As the vibration welding requires a certain minimum wall thickness in the region of the joint 11, and the wall thickness in the handle member 2 is generally smaller than the wall thickness required for welding, the joint 11 protrudes a distance beyond the surrounding surfaces 13, at least in areas where the surrounding surfaces 13 are planar, e g at the underside of the bridge portion 10.

The joint 11 has a particular structure, which contributes to its protrusion beyond its surrounding surfaces 13. During the vibration welding, the weld 18 proper will be formed between two surfaces in contact. Excess material may flow to the sides thereof. In order to maintain a unitary and snug appearance, two protecting members 19, 20 extend over and beyond the weld 18, forming an open space between themselves and the weld 18 for any excess material. All in all, the joint with its weld 18 and protecting members 19, 20 protrude beyond the surrounding surfaces 13.

On either side of the joint 11, protruding ribs 12 are provided at the bottom of the handle member 2. This is also clear from Fig. 3. Each rib 12 protrudes a distance from the adjacent bottom wall 13 of the handle member 2. The ribs 12, which are two in number in the preferred embodiment, protrude at least as far as the joint 11. Thus the bottom wall 13 is recessed in relation to the furthest protruding parts of the joint 11 and the ribs 12.

The ribs 12 are preferably placed on both sides of the joint 11 in the preferred embodiment. However, the distances from the respective ones of the ribs 12 to the joint 11 are not exactly the same, depending on the width of the bridge portion 10 and the positioning of the joint 11 thereon. The positioning of the joint in the bridge portion 10, and in the handle member 2 as a whole, depends mainly on manufacturing considerations.

The ribs 12 are arranged wholly or at least partially beneath the closed volume or volumes. Thus, not only the fuel tank 9 could be provided with ribs on its outside, but also the underside of the rear handle. In most cases, there is an internal wall between the rear handle 6 and the fuel tank 9, as well as an internal wall in the bridge portion 10, that separates part of it from the fuel tank.

In order to attain maximum beneficial effects from the ribs 12, they are preferably positioned as far apart as possible on the bridge portion 10, giving it a maximum torsion resistance, as well as protecting the entire underside from scratches and wear. The ribs also increase the bending resistance of the bridge portion 10.

Although the beneficial effect from arranging ribs 12, which protrude at least as far as the joint 11, is independent of the direction of extension of the ribs 12, they are arranged in the longitudinal direction of the bridge portion 10 in the preferred embodiment. The reason for this is twofold. Firstly, the manufacture of the two parts of the handle member 2 will be as simple as possible. Secondly, when the joint 11 and the ribs 12 extend in the same direction, the underside of the handle member 2 will be free from small recesses and enclosures, which may collect dirt or catch onto twigs or irregularities in the trees surfaces over which it passes.

The provision of two ribs alongside of each other will also greatly contribute to the stability of the chain saw 1 when it is placed on a planar surface, and keep it from falling over sideways, thus enhancing the feeling of quality, which may be of importance to a prospective buyer of the saw.

A look at the cross-sectional view in Fig. 4, taken along the line A-A in Fig. 3, will yield more information concerning the shape and location of the ribs 12. Also in this drawing, the thickness of material in the area of the joint 11 is shown clearly. The ribs 12 protrude from the surface 13 at the underside of the bridge portion 10 at least as far as the joint 11. Hereby, the outside height of the bridge portion 10 is substantially maintained, thus avoiding any need for redesigning other parts of the chain saw 1.

Likewise, the ribs 12 are positioned as far apart as the width of the bridge portion 10 will allow, without increasing the total outer dimensions of the bridge portion 10. This results in that the ribs 12 are placed in the vicinity of each of the side walls 14 in the bridge portion 10, without extending significantly outside of the side walls 14.

To make the ribs 12 as durable as possible, since the will be exposed to a major part of the wear when the chain saw 1 is pushed over logs or branches, the ribs 12 shall preferably have a wide support surface 15. At the same time, the thickness of material in the handle member 2 as a whole should preferably be as homogeneous as possible. In order to fulfill these two requirements, the ribs 12 have in the preferred embodiment been given the cross- sectional shape shown in Fig. 4. The support surfaces 15 extend along the bottom wall 13

at a distance there from forming a lower portion at each rib 12, while an upper portion, a perpendicular wall 16, extends between the bottom wall 13 and each support surface 15, such that a rib 12 with a hook-like cross-section is formed. The bottom wall 13, the side walls 14, the support surfaces 15, and the perpendicular wall 16 preferably all have the same thickness of material. The support surface 15 in each rib 12 is wider than the thickness of material, which makes it more durable. Each rib can also be lined with a harder material e.g. stainless steal. This could e.g. produce the T-shape shown in fig 5. Such ribs will of course have excellent resistance against scratching and wear.

An interior rib 17 extends from each side wall 14 in order to increase the stiffness of the bridge portion 10.

DESCRIPTION OF ALTERNATIVE EMBODIMENTS

The shape of the ribs 12 could of course be varied, as could the positioning thereof. Fig. 5 shows an alternative embodiment where the cross-sectional shape of the rib 12 is different from that of the preferred embodiment. One important thing to consider at the choice of the shape of the ribs 12 is keeping the thickness of material as homogeneous as possible. Secondly the ease of manufacture will also affect the choice of a suitable rib shape. Shapes that require a less complicated molding tool will be preferred.

If needed, the ribs 12 could be positioned at a smaller distance from each other and from the joint 11. The length of the ribs may be varied, and there may also be one or more interruptions, Le. instead of one long rib 12, there are a series of several shorter ribs 12 in line.

Although the embodiment where the ribs 12 are substantially parallel has been described above as a preferred embodiment, there may still be applications where ribs 12 that are disposed at an angle with the joint 11 will be useful.

The present invention may be modified and varied further without departing from the scope of the appended claims.