Handle for a Chain Saw

The invention relates to a bail-type handle for a portable handheld motor-driven chain saw. The handle is attachable to a motor housing of the chain saw by means of bearing portions and has a portion of tubular cross section.

In motor-driven chain saws, it is known to use handles produced from an aluminum alloy in various configurations. In one such embodiment, attachment flanges are provided at both ends of the actual handle and these flanges have receiving openings for attachment bolts. The tube of which the handle is made is not closed and is instead configured so as to be open.

Another embodiment of a tubular handle is likewise configured so as to be open; however, in this embodiment, a connecting part is provided as a handle between the two end portions, namely, the actual attachment portions thereof. This additional part is a part separate from the actual tubular handle and is secured with threaded bolts to the tube which is the holding handle.

Furthermore, so-called closed handles are also known for which the actual handle parts however lie essentially in one plane since the processing of the aluminum tube outside of this plane is unsuitable for mass production because of the high cost. A further disadvantage is that additional components such as bearing parts or air guide sheet metal pieces must be attached to the tubular handle with threaded fasteners or must be separately attached in some other manner.

Since the handles of motor-driven chain saws are subjected to intense vibrations, special measures must be taken in order to make the additional individual parts especially secure against vibration on the handle tube and to ensure against an unwanted loosening. Furthermore, the separate production of additional components and their attachment makes production complex and is expensive, especially, since the handles are a mass-produced article.

It is an object of the invention to provide a bail-shaped handle for a motor-driven chain saw which can be produced with simple means and at favorable cost. It is a further object of the invention to provide a handle of this kind which has a compact stable configuration with handle components which are integrated to provide a satisfactory function and which lie in different planes.

According to a special feature of the handle of the invention, parts can be integrated already during the production of the plastic body defining the handle. Previously, these parts were produced as separate parts and had to be attached to the handle tube. Such separate parts include the following: the bearing parts for the attachment to the motor housing; the seats for receiving the vibration attenuating elements; handle tube formations for guiding cooling air for which cooling air guide sheet metal pieces had to be previously provided and separately mounted on the handle tube; stops for the holding hand of the person operating the chain saw in order to specifically define the handle region; the configuration of hollow spaces or volumes for receiving operating means such as gasoline, oil or the like such that supply spaces in portions of the handle are integrated in the manner of a gasoline tank or an oil tank. Furthermore, the mounting of end stops for the attenuating elements and an individual adaptation of the spacial form of the handle attachments on corresponding attachment locations of the motor housing must be made directly in one work operation.

Furthermore, the handle can be advantageously so configured that it defines a unit which closes on itself, that is, a homogeneously closed part which must not be bolted together or assembled from different individual parts. In this way, the stiffness of the handle in its entirety is substantially increased. At the same time, the dimensions of the handle with respect to the configuration of the cross section and wall thicknesses can be reduced compared to other materials and/or handle configurations. A connecting strut can be provided between the attachment locations of the handle.

A further advantage is that to improve the graspability, the plastic body handle can be directly provided with grooving or scoring by appropriately shaping the actual handle surface and this would be in lieu of providing a separate hose-like grooved jacket. The essentially hollow plastic body handle can then be a homogeneous whole part incorporating all accessory parts with the cross sections and wall thicknesses of the handle being adapted to the function of the individual handle portions. For example, wall portions can be dimensioned with respect to their thicknesses thinner than other wall portions of the handle in accordance with the function to be performed. However, entire portions can be at least partially configured so as to be massive such as the attachment portions in correspondence to the mechanical loading; whereas, the cutouts for enclosing the counter attachment parts disposed on the motor housing in a form-tight manner can be precisely adapted to these counter attachment parts and can be hollow to correspond thereto.

The plastic body handle of the invention can be advantageously produced by thermal plastic injection or foaming. The plastic can preferably be a polyamide and, for the case where production is by foaming, the plastic can be supplemented with a foaming agent such as aceobicarbonate. If the handle is produced pursuant to the gas-inner-pressure process (a process wherein gas under pressure is admitted into a mold containing a plastic melt), the form cavity can be filled approximately to half with the plastic melt. This can take place at a temperature of approximately 250.degree. C. to 290.degree. C. After interrupting the supply of plastic, a gas, preferably nitrogen, is blown into the liquid plastic at a predetermined specific viscosity with the gas pressure being approximately 60 to 200 bar. The gas drives the plastic core ahead into the form with the liquid plastic coming to rest on the inner walls of the form so that the plastic body handle is formed in correspondence to the inner contours of the form with a hollow space being formed inside the handle by the pressure of the gas. The plastic used can be polyamide 6 and can be modified with an elastomer to increase its resistance to impact and, in addition, the plastic can be enriched with a stabilizing filter, preferably short glass fibers. The filler proportion can amount to approximately 30%.

The invention will now be described with reference to the drawings wherein:

FIG. 1 is a perspective view of the plastic body handle according to the invention;

FIG. 1a is other embodiment of the handle according to FIG. 1;

FIG. 2 is a side elevation view of the forward attachment portion of the handle of FIG. 1a viewed in the direction of arrow II of FIG. 1a;

FIG. 3 is a section view taken along line III--III of the forward attachment portion of the handle of FIG. 2;

FIG. 4 is a plan view of the rearward attachment portion of the handle of FIG. 1a viewed in the direction of arrow IV of FIG. 1a; and

FIG. 5 is a section view taken along line V--V of the rearward attachment portion of FIG. 4.

The plastic body handle 1 shown in the drawing is for a portable handheld motor-driven chain saw and can be attached to the motor housing. The essentially round-like plastic body handle 1 is closed upon itself and is produced pursuant to the so-called gas-inner-pressure process. The handle is for the most part hollow inside.

The plastic body handle 1 has a three-dimensional form with the upper holding handle portion 2 being ergometrically displaced with respect to the lower forward bearing portion 3 and a likewise lower rearward bearing portion 4. The bearing portions (3, 4) are connecting portions by means of which the handle is attached to the motor-driven chain saw. The holding portion 2 thereby lies in another plane than the lower portions (3, 4) which are provided for attaching the handle 1 to the motor housing. The holding handle portion 2 has a cross section which is essentially of tubular or circular cross section. It can also be advantageous to configure the holding handle portion 2 so as to have an oval cross section.

The handle portion 5 is provided between the upper holding handle portion 2 and the forward bearing portion 3 and is inclined. The handle portion 5 has receiving means 6 formed therein at approximately mid-elevation and at the lower end for accommodating respective attenuating elements. These receiving means 6 are made of the same material as the remainder of the handle and are unitary therewith and can be configured as a bearing eye or the like. Next to the bearing eye 6, abutment recesses 7 can be formed which are similar to a blind bore wherein corresponding abutments of the motor housing can engage. At the forward bearing portion 3 and/or rearward bearing portion 4, further recesses (8, 9) can be provided for the vibration attenuating elements. These recesses (8, 9) can be configured as hollow bearing seats or as bearing eyes.

Between the forward bearing portion 3 and the rearward bearing portion 4, a connecting strut 10 can be provided and be formed onto the handle and made of the same material so that the plastic body handle 1 is a closed entity. The connecting strut 10 and the approximately vertical handle portion 5 can be configured so as to have cross sections which are different than the tubular holding handle portion 2 and can, for example, be configured so as to be rectangular. Also, different wall thicknesses can be provided in correspondence to the different functional requirements so that thin-walled handle regions as well as thick-walled stable handle regions are provided.

In a preferred embodiment, the connecting strut 10 can be so configured that a tank chamber 11 is defined. That is, the tank chamber 11 is integrated into the connecting strut 10 in a space-saving manner. The tank chamber 11 can serve to receive liquid operating means such as gasoline or oil. The tank chamber 11 can also contain a lubricant which can be metered to the saw chain guided for movement around the guide bar during operation of the motor-driven chain saw.

In a further embodiment of the plastic body handle 1, even motor covering parts and especially air guiding parts 12 can be provided which are positioned directly toward the motor. In the present embodiment, the air guiding part 12 is formed on the handle portion 5. By forming the air guide portion 12 on the handle so that it is of the same material and unitary therewith, the advantage is provided that a portion of the mass of the vibrating tool is taken away and assigned to the plastic body handle 1 journalled so as to be damped against vibration so that a reduction against oscillations is provided.

Furthermore, it should be noted that the holding handle portion 2 of the plastic body handle 1 can be provided with scoring or grooving 13 through appropriate forming of the surface with the plastic body handle 1 being preferably produced pursuant to the inner-pressure process described above. In this way, an improvement in grasping is achieved without the need to provide a separate hose-like jacket. It is also possible to provide the holding handle portion 2 with a protective covering made of elastic material such as rubber, thermoplastic material or the like.

The plastic handle 1 according to the invention can be produced according to the gas-inner-pressure process with all functional parts 2 to 13 described above and can be produced as a total part which is homogeneous so that a compact component is provided which can be produced as a mass-produced article having uniformly high quality and which has the lowest possible weight as well as a durable stability. Furthermore, the plastic body handle 1 of the invention has a low heat conductivity so that a handling free of difficulty is assured in summer as well as in winter at low temperatures.

It is also possible to produce the new handle with a connecting strut 10 and bearing portions (3, 4) by means of a plastic foaming process.

It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.